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000
FXUS63 KLSX 220950
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
350 AM CST Mon Dec 22 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 350 AM CST Mon Dec 22 2014

Full latitude trof over the Great Plains will continue to deepen
today.  All guidance is pointing toward widespread light rain as the
low level jet ramps up ahead of the trof.  Models show moderate
moisture convergence at 850mb and widespread QPF across the area.
Highest rainfall amounts will likely be along and north of the I-70
corridor with amounts up to 1/2 inch.  With a warmer start to the
day and south-southeast flow, should see temperatures a little
warmer than yesterday, tho widespread rain will keep highs in the
mid 40s to around 50.

Carney

.LONG TERM:  (Tonight through Sunday)
Issued at 350 AM CST Mon Dec 22 2014

(Tonight - Tuesday Evening)

An upper level TROF will already be established over the Plains by
this time with a strong impulse rotating around its base that should
move thru a good chunk of the forecast area during the evening
hours.  This should initially result in widespread rain for most
areas, especially areas immediately downstream from this impulse,
such as areas mainly to the north of I-70.  MOS guidance low-balling
this too much and went well above MOS for PoPs, with most areas
forecast with likely to categorical PoPs.

In the wake of the impulse this evening, a dry slot is then expected
to take hold and persist from late tonight thru Tuesday evening.
Preferred small diurnal ranges with this setup, which favors the
warmer MOS temps for tonight and cooler MOS temps for Tuesday.

Pcpn-types thru this period are expected to be rain.

(Late Tuesday Night - Christmas Eve)

For the first time in several days, a good model consensus has
developed on the final phase for this system.  Previously the GFS
was the outlier, being the sole model that took a strong disturbance
from the Pacific NW that quickly dropped into the bottom of the TROF
and used it to close off a new LOW near the AR/OK border late
Tuesday night and then track it northeastward into Indiana Wednesday
evening.  Well now the EC and GEM have come onboard with this
solution, giving greater credence to this--abandoning their previous
advocation of an open wave.

The key disturbance from the Pacific NW was coming onshore when the
00z models were initialized and so a convergence of solutions was
anticipated.

Even if this has a stronger possibility of happening, though, there
are still issues.  But at least it looks to solve the PoP problem--
with what should be a deformation pcpn axis of developing by
daybreak Wednesday primarily over southern and eastern IL and
persisting until evening.  The western edge looks to be over Metro
STL East.  The elongated upper TROF axis that does result, however,
will probably still spread light pcpn over areas further to the west
though, with the enhanced amounts in the deformation zone in the
east.

The issues still remaining are a pcpn-type one, with what still
looks to be sufficient cold air aloft to then defer all pcpn-type
issues to the lowest 2kft, especially how cold surface temps manage
to get.  The problem is that there is very little cold air to tap
other than what gets manufactured by the system itself.  MOS will
typically handle temps with these systems not very well, and so
undercut values by at least a category, as we should rise very
little during the day, especially under the anticipated deformation
zone.  This should give us surface temps in the mid 30s mostly, with
some upper 30s.  The atmospheric setup, despite temps above
freezing, should support mostly snow.  But warm ground and surfaces
with these above freezing temps should severely limit any snow
accums, if any occur at all.

So...it looks like a dusting of snow on grassy areas is what is
expected to occur for most locations, with the best potential for
grassy area accums being under the def zone in parts of
southern-eastern IL where up to an inch is possible.  As it stands
now, this should not affect travel much.

If a colder solution than this presents itself, snow accums will
have to be substantially increased.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Sunday)

The upper TROF becomes re-established over the central CONUS with
weak disturbances and a cold front moving thru early in the period.
Have small PoPs to cover for now, with a return then to below normal
temps for next weekend in the wake of the front.

TES

&&

.AVIATION:  (For the 06z TAFs through 06z Monday Night)
Issued at 1103 PM CST Sun Dec 21 2014

Focus continues to system to impact the region on Mon. Latest
guidance, while not having a great handle on current conditions,
continues to suggest prev TAFs are on track. Believe conditions
will deteriorate shortly after sunrise Mon. Cigs shud lower to low
end MVFR as well as visbys reduced into MVFR range due to either
RA, BR or both. Latest indications suggest RA may have a more SHRA
component, but during dry periods, while brief, visbys shud still
be reduced due to BR. Have low confidence on visbys on Mon and may
drop to IFR at times. Confidence in IFR at SUS/CPS remains low and
will keep trends going for now. Winds will veer to eventually swly
Mon evening with visbys and cigs improving with this wind shift.

Specifics for KSTL: VFR and dry expected thru the overnight hours
with conditions deteriorating shortly after sunrise. Confidence in
IFR conditions is still too low and will therefore keep sct cloud
deck mentioned for now. Conditions will improve Mon late
afternoon or evening as winds become swly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





000
FXUS63 KLSX 220950
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
350 AM CST Mon Dec 22 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 350 AM CST Mon Dec 22 2014

Full latitude trof over the Great Plains will continue to deepen
today.  All guidance is pointing toward widespread light rain as the
low level jet ramps up ahead of the trof.  Models show moderate
moisture convergence at 850mb and widespread QPF across the area.
Highest rainfall amounts will likely be along and north of the I-70
corridor with amounts up to 1/2 inch.  With a warmer start to the
day and south-southeast flow, should see temperatures a little
warmer than yesterday, tho widespread rain will keep highs in the
mid 40s to around 50.

Carney

.LONG TERM:  (Tonight through Sunday)
Issued at 350 AM CST Mon Dec 22 2014

(Tonight - Tuesday Evening)

An upper level TROF will already be established over the Plains by
this time with a strong impulse rotating around its base that should
move thru a good chunk of the forecast area during the evening
hours.  This should initially result in widespread rain for most
areas, especially areas immediately downstream from this impulse,
such as areas mainly to the north of I-70.  MOS guidance low-balling
this too much and went well above MOS for PoPs, with most areas
forecast with likely to categorical PoPs.

In the wake of the impulse this evening, a dry slot is then expected
to take hold and persist from late tonight thru Tuesday evening.
Preferred small diurnal ranges with this setup, which favors the
warmer MOS temps for tonight and cooler MOS temps for Tuesday.

Pcpn-types thru this period are expected to be rain.

(Late Tuesday Night - Christmas Eve)

For the first time in several days, a good model consensus has
developed on the final phase for this system.  Previously the GFS
was the outlier, being the sole model that took a strong disturbance
from the Pacific NW that quickly dropped into the bottom of the TROF
and used it to close off a new LOW near the AR/OK border late
Tuesday night and then track it northeastward into Indiana Wednesday
evening.  Well now the EC and GEM have come onboard with this
solution, giving greater credence to this--abandoning their previous
advocation of an open wave.

The key disturbance from the Pacific NW was coming onshore when the
00z models were initialized and so a convergence of solutions was
anticipated.

Even if this has a stronger possibility of happening, though, there
are still issues.  But at least it looks to solve the PoP problem--
with what should be a deformation pcpn axis of developing by
daybreak Wednesday primarily over southern and eastern IL and
persisting until evening.  The western edge looks to be over Metro
STL East.  The elongated upper TROF axis that does result, however,
will probably still spread light pcpn over areas further to the west
though, with the enhanced amounts in the deformation zone in the
east.

The issues still remaining are a pcpn-type one, with what still
looks to be sufficient cold air aloft to then defer all pcpn-type
issues to the lowest 2kft, especially how cold surface temps manage
to get.  The problem is that there is very little cold air to tap
other than what gets manufactured by the system itself.  MOS will
typically handle temps with these systems not very well, and so
undercut values by at least a category, as we should rise very
little during the day, especially under the anticipated deformation
zone.  This should give us surface temps in the mid 30s mostly, with
some upper 30s.  The atmospheric setup, despite temps above
freezing, should support mostly snow.  But warm ground and surfaces
with these above freezing temps should severely limit any snow
accums, if any occur at all.

So...it looks like a dusting of snow on grassy areas is what is
expected to occur for most locations, with the best potential for
grassy area accums being under the def zone in parts of
southern-eastern IL where up to an inch is possible.  As it stands
now, this should not affect travel much.

If a colder solution than this presents itself, snow accums will
have to be substantially increased.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Sunday)

The upper TROF becomes re-established over the central CONUS with
weak disturbances and a cold front moving thru early in the period.
Have small PoPs to cover for now, with a return then to below normal
temps for next weekend in the wake of the front.

TES

&&

.AVIATION:  (For the 06z TAFs through 06z Monday Night)
Issued at 1103 PM CST Sun Dec 21 2014

Focus continues to system to impact the region on Mon. Latest
guidance, while not having a great handle on current conditions,
continues to suggest prev TAFs are on track. Believe conditions
will deteriorate shortly after sunrise Mon. Cigs shud lower to low
end MVFR as well as visbys reduced into MVFR range due to either
RA, BR or both. Latest indications suggest RA may have a more SHRA
component, but during dry periods, while brief, visbys shud still
be reduced due to BR. Have low confidence on visbys on Mon and may
drop to IFR at times. Confidence in IFR at SUS/CPS remains low and
will keep trends going for now. Winds will veer to eventually swly
Mon evening with visbys and cigs improving with this wind shift.

Specifics for KSTL: VFR and dry expected thru the overnight hours
with conditions deteriorating shortly after sunrise. Confidence in
IFR conditions is still too low and will therefore keep sct cloud
deck mentioned for now. Conditions will improve Mon late
afternoon or evening as winds become swly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX






000
FXUS63 KLSX 220513
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1113 PM CST Sun Dec 21 2014

.UPDATE:
Issued at 925 PM CST Sun Dec 21 2014

Cloudy skies have moved into all but the far eastern part of the
CWA at this hour. Latest trends suggests that this area will cloud
over within the hour, so expect the entire area to return to being
cloudy the rest of the night. With clouds and a bit higher winds,
do not expect temperatures to fall more than a few degrees tonight,
so raised going temperatures a bit in a few areas. Expanded the
slight chances for light rain eastward late tonight across eastern
Missouri as low level moisture convergence will increase ahead of
weak shortwave trough that is rounding base of trough currently
over the southern Plains.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 06z TAFs through 06z Monday Night)
Issued at 1103 PM CST Sun Dec 21 2014

Focus continues to system to impact the region on Mon. Latest
guidance, while not having a great handle on current conditions,
continues to suggest prev TAFs are on track. Believe conditions
will deteriorate shortly after sunrise Mon. Cigs shud lower to low
end MVFR as well as visbys reduced into MVFR range due to either
RA, BR or both. Latest indications suggest RA may have a more SHRA
component, but during dry periods, while brief, visbys shud still
be reduced due to BR. Have low confidence on visbys on Mon and may
drop to IFR at times. Confidence in IFR at SUS/CPS remains low and
will keep trends going for now. Winds will veer to eventually swly
Mon evening with visbys and cigs improving with this wind shift.

Specifics for KSTL: VFR and dry expected thru the overnight hours
with conditions deteriorating shortly after sunrise. Confidence in
IFR conditions is still too low and will therefore keep sct cloud
deck mentioned for now. Conditions will improve Mon late
afternoon or evening as winds become swly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 220513
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1113 PM CST Sun Dec 21 2014

.UPDATE:
Issued at 925 PM CST Sun Dec 21 2014

Cloudy skies have moved into all but the far eastern part of the
CWA at this hour. Latest trends suggests that this area will cloud
over within the hour, so expect the entire area to return to being
cloudy the rest of the night. With clouds and a bit higher winds,
do not expect temperatures to fall more than a few degrees tonight,
so raised going temperatures a bit in a few areas. Expanded the
slight chances for light rain eastward late tonight across eastern
Missouri as low level moisture convergence will increase ahead of
weak shortwave trough that is rounding base of trough currently
over the southern Plains.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 06z TAFs through 06z Monday Night)
Issued at 1103 PM CST Sun Dec 21 2014

Focus continues to system to impact the region on Mon. Latest
guidance, while not having a great handle on current conditions,
continues to suggest prev TAFs are on track. Believe conditions
will deteriorate shortly after sunrise Mon. Cigs shud lower to low
end MVFR as well as visbys reduced into MVFR range due to either
RA, BR or both. Latest indications suggest RA may have a more SHRA
component, but during dry periods, while brief, visbys shud still
be reduced due to BR. Have low confidence on visbys on Mon and may
drop to IFR at times. Confidence in IFR at SUS/CPS remains low and
will keep trends going for now. Winds will veer to eventually swly
Mon evening with visbys and cigs improving with this wind shift.

Specifics for KSTL: VFR and dry expected thru the overnight hours
with conditions deteriorating shortly after sunrise. Confidence in
IFR conditions is still too low and will therefore keep sct cloud
deck mentioned for now. Conditions will improve Mon late
afternoon or evening as winds become swly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 220345
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
945 PM CST Sun Dec 21 2014

.UPDATE:
Issued at 925 PM CST Sun Dec 21 2014

Cloudy skies have moved into all but the far eastern part of the
CWA at this hour. Latest trends suggests that this area will cloud
over within the hour, so expect the entire area to return to being
cloudy the rest of the night. With clouds and a bit higher winds,
do not expect temperatures to fall more than a few degrees tonight,
so raised going temperatures a bit in a few areas. Expanded the
slight chances for light rain eastward late tonight across eastern
Missouri as low level moisture convergence will increase ahead of
weak shortwave trough that is rounding base of trough currently
over the southern Plains.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 00z TAFs through 00z Monday Evening)
Issued at 526 PM CST Sun Dec 21 2014

While main focus will be precip and cigs on Mon, will also need to
focus on cigs for a few hours this evening, mainly at UIN. Believe
COU will lift to VFR at or shortly after 00z as the TAFs become
valid. UIN has become MVFR and will likely drop below 2 kft for a
few hours this evening. However, this is somewhat uncertain as the
low level flow shud become more sly. Otherwise, winds will remain
sely to ssely until Mon afternoon as the precip ends. Expect cigs
to drop around or shortly after sunrise Mon as precip begins,
then drop to IFR at COU/UIN mid to late morning. IFR cigs at
SUS/CPS on Mon is more uncertain and have only hinted at IFR
possible for now.

Specifics for KSTL: VFR and dry conditions expected thru tonight.
Expect MVFR cigs to move in around sunrise with precip beginning
shortly after. IFR cigs will be possible, but confidence is too
low attm. Expect precip to come to an end around 00z Tues with
winds veering to become sly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 220345
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
945 PM CST Sun Dec 21 2014

.UPDATE:
Issued at 925 PM CST Sun Dec 21 2014

Cloudy skies have moved into all but the far eastern part of the
CWA at this hour. Latest trends suggests that this area will cloud
over within the hour, so expect the entire area to return to being
cloudy the rest of the night. With clouds and a bit higher winds,
do not expect temperatures to fall more than a few degrees tonight,
so raised going temperatures a bit in a few areas. Expanded the
slight chances for light rain eastward late tonight across eastern
Missouri as low level moisture convergence will increase ahead of
weak shortwave trough that is rounding base of trough currently
over the southern Plains.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 00z TAFs through 00z Monday Evening)
Issued at 526 PM CST Sun Dec 21 2014

While main focus will be precip and cigs on Mon, will also need to
focus on cigs for a few hours this evening, mainly at UIN. Believe
COU will lift to VFR at or shortly after 00z as the TAFs become
valid. UIN has become MVFR and will likely drop below 2 kft for a
few hours this evening. However, this is somewhat uncertain as the
low level flow shud become more sly. Otherwise, winds will remain
sely to ssely until Mon afternoon as the precip ends. Expect cigs
to drop around or shortly after sunrise Mon as precip begins,
then drop to IFR at COU/UIN mid to late morning. IFR cigs at
SUS/CPS on Mon is more uncertain and have only hinted at IFR
possible for now.

Specifics for KSTL: VFR and dry conditions expected thru tonight.
Expect MVFR cigs to move in around sunrise with precip beginning
shortly after. IFR cigs will be possible, but confidence is too
low attm. Expect precip to come to an end around 00z Tues with
winds veering to become sly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 212333
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
533 PM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 00z TAFs through 00z Monday Evening)
Issued at 526 PM CST Sun Dec 21 2014

While main focus will be precip and cigs on Mon, will also need to
focus on cigs for a few hours this evening, mainly at UIN. Believe
COU will lift to VFR at or shortly after 00z as the TAFs become
valid. UIN has become MVFR and will likely drop below 2 kft for a
few hours this evening. However, this is somewhat uncertain as the
low level flow shud become more sly. Otherwise, winds will remain
sely to ssely until Mon afternoon as the precip ends. Expect cigs
to drop around or shortly after sunrise Mon as precip begins,
then drop to IFR at COU/UIN mid to late morning. IFR cigs at
SUS/CPS on Mon is more uncertain and have only hinted at IFR
possible for now.

Specifics for KSTL: VFR and dry conditions expected thru tonight.
Expect MVFR cigs to move in around sunrise with precip beginning
shortly after. IFR cigs will be possible, but confidence is too
low attm. Expect precip to come to an end around 00z Tues with
winds veering to become sly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 212333
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
533 PM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 00z TAFs through 00z Monday Evening)
Issued at 526 PM CST Sun Dec 21 2014

While main focus will be precip and cigs on Mon, will also need to
focus on cigs for a few hours this evening, mainly at UIN. Believe
COU will lift to VFR at or shortly after 00z as the TAFs become
valid. UIN has become MVFR and will likely drop below 2 kft for a
few hours this evening. However, this is somewhat uncertain as the
low level flow shud become more sly. Otherwise, winds will remain
sely to ssely until Mon afternoon as the precip ends. Expect cigs
to drop around or shortly after sunrise Mon as precip begins,
then drop to IFR at COU/UIN mid to late morning. IFR cigs at
SUS/CPS on Mon is more uncertain and have only hinted at IFR
possible for now.

Specifics for KSTL: VFR and dry conditions expected thru tonight.
Expect MVFR cigs to move in around sunrise with precip beginning
shortly after. IFR cigs will be possible, but confidence is too
low attm. Expect precip to come to an end around 00z Tues with
winds veering to become sly.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 212156
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
356 PM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1132 AM CST Sun Dec 21 2014

Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR at taf sites along I-70. KUIN
should see cigs lift to low end VFR by 00z Monday. Otherwise,
winds to persist from the southeast to south through forecast
period. Next weather system to approach region tonight, will see
rain develop over western MO and spread east, moving into KUIN and
KCOU by 14z Monday and metro area by 18z Monday. When rain begins
to move in, will see cigs/vsbys lower to mvfr.

Specifics for KSTL:
Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR in metro area. Otherwise, winds
to persist from the southeast to south through forecast period.
Next weather system to approach region tonight, will see rain
develop over western MO and spread east, moving into metro area by
18z Monday. When rain begins to move in, will see cigs/vsbys lower
to mvfr.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 212156
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
356 PM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1132 AM CST Sun Dec 21 2014

Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR at taf sites along I-70. KUIN
should see cigs lift to low end VFR by 00z Monday. Otherwise,
winds to persist from the southeast to south through forecast
period. Next weather system to approach region tonight, will see
rain develop over western MO and spread east, moving into KUIN and
KCOU by 14z Monday and metro area by 18z Monday. When rain begins
to move in, will see cigs/vsbys lower to mvfr.

Specifics for KSTL:
Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR in metro area. Otherwise, winds
to persist from the southeast to south through forecast period.
Next weather system to approach region tonight, will see rain
develop over western MO and spread east, moving into metro area by
18z Monday. When rain begins to move in, will see cigs/vsbys lower
to mvfr.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 212156
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
356 PM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 334 PM CST Sun Dec 21 2014

Low level moisture will be on the increase late tonight ahead of
next weather system, but rain will not move into central and
northeast Missouri, west central Illinois til after midnight.
Otherwise, cloudy conditions to persist with low temperatures only
in the low 30s over far eastern sections to around 40 over central
Missouri, so do not need to worry about any freezing or frozen
precipitation.

Byrd

.LONG TERM:  (Monday through Next Sunday)
Issued at 334 PM CST Sun Dec 21 2014

(Monday - Wednesday)

All guidance based off of the 21/12z model cycle still giving strong
support to going forecast trends that indicate a rainy Monday is in
the offing for most of the CWA.  Upper trof over the central CONUS
will be deepening over the next 12 hours as several shortwaves work
into the mean trof position, with the strongest of these pushing
into the mid MO valley on Monday morning and closing off into an
upper low over IA by Monday afternoon and evening. As this system
approaches late tonight and early Monday, southerly flow will
increase through the lower troposphere leading to a significant
deepening of the moisture over the region.  Ascent from the
approaching upper level dynamics combined with the low level
isentropic ascent should produce a fairly rapid increase of rainfall
across most of the area during the morning hours, with this rain
continuing over much FA into the afternoon.

Dry slot will be wrapping into the system Monday night as the system
occludes, with model consensus of the translation of the dry slot
suggesting that rainfall will be diminishing from NW to SE across
the CWA on Monday night.  By 12z Tuesday, relatively dry air will be
over NW sections of the CWA, while on the se fringes of the dry
slot deep moisture and baroclinicity will draped from AR into the
lower Ohio Valley. will carry a chance of precip over about the
SE 2/3 of the CWA on Tuesday, with highest PoPs over SE sections
of the FA closer to the aforementioned moisture and baroclinic zone.

This leads into a very tricky forecast heading into midweek, as
longwave trof lingers over the CONUS. This is one of the trickier
patterns of the winter season, as models often struggle with speed
and intensity of shortwaves that are meandering through the trof.
And in this case, forecast concerns are amplified due to the fact
that strong low level baroclinicity and deep moisture...two key
ingredients for strong synoptic scale winter systems...will be
lurking just off to our SE.  Models have already been struggling
with the evolution of this pattern... last nights 00z GFS and off-
cycle 06z NAM runs hinted at low closing off to our south with
accumulating snow for a large part of our FA, but 12z runs are
less bullish on this forecast, and suggest more of an open system
that will produce heavier precip in the warmer air over parts of
the Ohio Valley and areas east.

In this pattern, odds are extremely high that individual solutions
will continue to flip-flop on exact trends, so at this juncture feel
most comfortable leaning on model consensus for the large scale
forecast details.

In general, the weather on Tuesday night and Christmas Eve Day
should become a bit more unsettled as another shortwave enters
the base of the longwave trof and the entire system begins to push
east. This should certainly generate another wave of precip, but
the big question is where.  GFS remains the most robust model in
regards to precip during this time, with measurable QPF over about
the eastern half of the CWA, while all the other solutions focus
this axis from extreme e AR into KY and TN. Forecast soundings
indicate the low level AMS over our SE counties (where the QPF
would be heaviest) will be too warm for any frozen precip Tuesday
night, but may cool off enough to support some snow during the day
on Wednesday as the precip winds down. Thermal profile looks more
favorable for snow over our NW counties, but here the precip
should be quite light.

At this point, accumulating snow in any part of our CWA look
iffy. But once again this is a tricky pattern...so holiday
travelers should continue to monitor the latest forecasts.

(Christmas Day - Sunday)

It now appears that Christmas Day will be fairly tranquil and
relatively mild as upper trof pushes east and ridging temporarily
allows warmer air to build into the central CONUS.

Medium range consensus remains fairly good into Friday, as a lead
shortwave begins the process of developing another trof axis over
the central CONUS.  Have maintained some slight chance PoPs as the
shortwave pushes through the region.

Although medium range models diverge heading into next weekend
with the location and intensity of the upper level trof, lowering
of heights should yield below normal temps.

Truett

&&

.AVIATION:  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1132 AM CST Sun Dec 21 2014

Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR at taf sites along I-70. KUIN
should see cigs lift to low end VFR by 00z Monday. Otherwise,
winds to persist from the southeast to south through forecast
period. Next weather system to approach region tonight, will see
rain develop over western MO and spread east, moving into KUIN and
KCOU by 14z Monday and metro area by 18z Monday. When rain begins
to move in, will see cigs/vsbys lower to mvfr.

Specifics for KSTL:
Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR in metro area. Otherwise, winds
to persist from the southeast to south through forecast period.
Next weather system to approach region tonight, will see rain
develop over western MO and spread east, moving into metro area by
18z Monday. When rain begins to move in, will see cigs/vsbys lower
to mvfr.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 211738
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1138 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES
&&

.AVIATION:  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1132 AM CST Sun Dec 21 2014

Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR at taf sites along I-70. KUIN
should see cigs lift to low end VFR by 00z Monday. Otherwise,
winds to persist from the southeast to south through forecast
period. Next weather system to approach region tonight, will see
rain develop over western MO and spread east, moving into KUIN and
KCOU by 14z Monday and metro area by 18z Monday. When rain begins
to move in, will see cigs/vsbys lower to mvfr.

Specifics for KSTL:
Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR in metro area. Otherwise, winds
to persist from the southeast to south through forecast period.
Next weather system to approach region tonight, will see rain
develop over western MO and spread east, moving into metro area by
18z Monday. When rain begins to move in, will see cigs/vsbys lower
to mvfr.

Byrd
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$
WFO LSX






000
FXUS63 KLSX 211738
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1138 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES
&&

.AVIATION:  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1132 AM CST Sun Dec 21 2014

Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR at taf sites along I-70. KUIN
should see cigs lift to low end VFR by 00z Monday. Otherwise,
winds to persist from the southeast to south through forecast
period. Next weather system to approach region tonight, will see
rain develop over western MO and spread east, moving into KUIN and
KCOU by 14z Monday and metro area by 18z Monday. When rain begins
to move in, will see cigs/vsbys lower to mvfr.

Specifics for KSTL:
Southeast flow at the surface is helping to bring in drier air, so
cigs have lifted to low end VFR in metro area. Otherwise, winds
to persist from the southeast to south through forecast period.
Next weather system to approach region tonight, will see rain
develop over western MO and spread east, moving into metro area by
18z Monday. When rain begins to move in, will see cigs/vsbys lower
to mvfr.

Byrd
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$
WFO LSX







000
FXUS63 KLSX 211207
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
607 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Monday Morning)
Issued at 556 AM CST Sun Dec 21 2014
MVFR Flight conditions will prevail across most of the area for
much of the day today. Expect that ceilings will improve to VFR
along and south of the I-70 corridor, and there will probably be
some breaks in the overcast across southeast Missouri and southern
Illinois.

Specifics for KSTL:
MVFR flight conditions will prevail at Lambert this morning.
Ceilings should improve to VFR this afternoon, although timing is
uncertain. VFR ceilings will likely hold through the night, but
should fall again sometime Monday morning. Timing of the falling
ceilings and heights are uncertain at this time.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX









000
FXUS63 KLSX 211207
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
607 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Monday Morning)
Issued at 556 AM CST Sun Dec 21 2014
MVFR Flight conditions will prevail across most of the area for
much of the day today. Expect that ceilings will improve to VFR
along and south of the I-70 corridor, and there will probably be
some breaks in the overcast across southeast Missouri and southern
Illinois.

Specifics for KSTL:
MVFR flight conditions will prevail at Lambert this morning.
Ceilings should improve to VFR this afternoon, although timing is
uncertain. VFR ceilings will likely hold through the night, but
should fall again sometime Monday morning. Timing of the falling
ceilings and heights are uncertain at this time.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 211207
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
607 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Monday Morning)
Issued at 556 AM CST Sun Dec 21 2014
MVFR Flight conditions will prevail across most of the area for
much of the day today. Expect that ceilings will improve to VFR
along and south of the I-70 corridor, and there will probably be
some breaks in the overcast across southeast Missouri and southern
Illinois.

Specifics for KSTL:
MVFR flight conditions will prevail at Lambert this morning.
Ceilings should improve to VFR this afternoon, although timing is
uncertain. VFR ceilings will likely hold through the night, but
should fall again sometime Monday morning. Timing of the falling
ceilings and heights are uncertain at this time.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX









000
FXUS63 KLSX 211207
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
607 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Monday Morning)
Issued at 556 AM CST Sun Dec 21 2014
MVFR Flight conditions will prevail across most of the area for
much of the day today. Expect that ceilings will improve to VFR
along and south of the I-70 corridor, and there will probably be
some breaks in the overcast across southeast Missouri and southern
Illinois.

Specifics for KSTL:
MVFR flight conditions will prevail at Lambert this morning.
Ceilings should improve to VFR this afternoon, although timing is
uncertain. VFR ceilings will likely hold through the night, but
should fall again sometime Monday morning. Timing of the falling
ceilings and heights are uncertain at this time.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 210940
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
340 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES

&&

.AVIATION:  (For the 06z TAFs through 06z Sunday Night)
Issued at 1117 PM CST Sat Dec 20 2014

Focus will continue to be cigs thru the period. Guidance continues
to handle the current trends poorly across the region. Have
therefore continued low confidence in cig heights, but believe
overall trends are reflected in TAFs. Believe conditions will
remain largely as-is except UIN becoming MVFR in the next hour or so.
Cigs shud slowly lift Sun around Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing remains uncertain.

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





000
FXUS63 KLSX 210940
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
340 AM CST Sun Dec 21 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 340 AM CST Sun Dec 21 2014

A full latitude trof is moving through the Great Plains this
morning; and although the pattern is relatively low amplitude, the
trof will begin deepening today as the strong shortwave over the
Pacific Northwest moves rapidly across the Rockies and dives into
the Great Plains.  This will result in increasing southerly flow in
the low levels as the trof deepens over the Plains.  Unfortunately,
plenty of moisture will remain trapped under the persistent
inversion which has been locked in over the CWFA for the past few
days.  Present indications are that the sky will remain cloudy
across most of the area today; but there is potential for some
breaks in the overcast during the afternoon along and south of the
I-44 corridor.  Highs today will likely be near or just a few
degrees warmer than yesterday`s temperatures.

Carney

.LONG TERM:  (Tonight through Saturday)
Issued at 340 AM CST Sun Dec 21 2014

(Tonight - Wednesday)

There remains good model consensus on a deep longwave upper level
TROF becoming established over the central CONUS by Monday...right
over our region...and then taking until Wednesday before exiting.
It is the specifics on the last 24 hours that remains elusive and
probably will for at least another day or so until a critical
component can finally come ashore.

The initial phase tonight and Monday will feature some deepening of
the TROF to our west with most of the pcpn staying to the N and W of
STL metro.  Pcpn-types here will be all liquid.

The middle phase Monday night and Tuesday will then feature
significant deepening and amplification of the TROF with higher
levels of moisture and additional disturbances riding northward.  At
this time, it looks like much of the moisture will get shunted off
to the east and so have the best PoPs generally for STL metro and
areas to the S and E.  Pcpn-types once again will be all liquid.

The final phase for Tuesday night and Wednesday, arguably the most
important one, is where the models still have significant diffs on.
All solutions continue to trend slower with bringing the TROF axis
thru our region, but differ on exactly how to do that.  The GFS is
the most extreme in closing off a LOW over western AR and then
tracking it northeast into the lower OH valley.  This would paint a
solution of accumulating snow for a good chunk of our region late
Tuesday night into Wednesday (Christmas Eve).  The EC and GEM
continue to lead the opposition by maintaining an open wave with
this southern disturbance and maintaining a LOW to the north.  This
would end up leaving very little pcpn back in the cold air with what
edges us from the deformation zone well to the north and scattered
SHSN in its wake.  Spotty dustings of snow would be the likely
result here.  Both the 00z and 06z NAM have somewhat more of a
compromise between these two camps.  Vertical temp profiles favor
rain changing to snow for most areas Tuesday night, especially west
of STL city, continuing to trend snowier for Wednesday.  Sufficient
cold air should be aloft to not have to worry about mixed pcpn,
especially if the GFS verifies, with upper LOs notorious for
manufacturing their own cold air, and will almost exclusively come
down to temps in the lowest 2kft of the atmosphere, with decent
correlation to surface temps:  where surface temps are mid 30s or
below, this should favor mostly snow, with liquid for upper 30s and
up.  Have maintained the going course of preferred snow for the
pcpn-types but spreads are much too large to properly speculate on
amounts or impacts at this time, but with surface temps mostly above
freezing and recent mild air, it will take strong snowfall rates to
successfully achieve decent accums anyway and would need the GFS
solution to win out.

Mild temps forecast thru Tuesday, with below normal temps for
Wednesday.

(Christmas)

Models continue to advertise a transitional pattern this day with
quiet wx and temps returning to above normal levels.

(Friday - Saturday)

There is better model agreement than 24hrs ago, with a
re-establishment of a longwave upper TROF over the central CONUS and
an area of sheared vorticity moving thru.  Coupled with a cold front
on Friday, it is worth a PoP mention but amounts look sparse at this
time.

TES

&&

.AVIATION:  (For the 06z TAFs through 06z Sunday Night)
Issued at 1117 PM CST Sat Dec 20 2014

Focus will continue to be cigs thru the period. Guidance continues
to handle the current trends poorly across the region. Have
therefore continued low confidence in cig heights, but believe
overall trends are reflected in TAFs. Believe conditions will
remain largely as-is except UIN becoming MVFR in the next hour or so.
Cigs shud slowly lift Sun around Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing remains uncertain.

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX






000
FXUS63 KLSX 210520
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1120 PM CST Sat Dec 20 2014

.UPDATE:
Issued at 924 PM CST Sat Dec 20 2014

Clouds are lingering over the entire CWA this evening and will
likely do so into the overnight hours as we are experiencing one
of the longest nights of the year. Latest satellite observations
has shown that low clouds are expanding slowly  eastward over
east central/southeast Illinois while there has been very little
movement over southeast Missouri. Latest ACARS sounding from KSTL
shows a decent inversion between 900-850mb with plenty of moisture
below it, and the RAP keeps plenty of low level moisture over the
CWA tonight, so left cloudy skies over the CWA the rest of the
night. Also raised temperatures tonight, particularly in the
southern and eastern counties where clearing was previously
forecast.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting yesterday. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 06z TAFs through 06z Sunday Night)
Issued at 1117 PM CST Sat Dec 20 2014

Focus will continue to be cigs thru the period. Guidance continues
to handle the current trends poorly across the region. Have
therefore continued low confidence in cig heights, but believe
overall trends are reflected in TAFs. Believe conditions will
remain largely as-is except UIN becoming MVFR in the next hour or so.
Cigs shud slowly lift Sun around Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing remains uncertain.


&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 210520
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1120 PM CST Sat Dec 20 2014

.UPDATE:
Issued at 924 PM CST Sat Dec 20 2014

Clouds are lingering over the entire CWA this evening and will
likely do so into the overnight hours as we are experiencing one
of the longest nights of the year. Latest satellite observations
has shown that low clouds are expanding slowly  eastward over
east central/southeast Illinois while there has been very little
movement over southeast Missouri. Latest ACARS sounding from KSTL
shows a decent inversion between 900-850mb with plenty of moisture
below it, and the RAP keeps plenty of low level moisture over the
CWA tonight, so left cloudy skies over the CWA the rest of the
night. Also raised temperatures tonight, particularly in the
southern and eastern counties where clearing was previously
forecast.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting yesterday. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 06z TAFs through 06z Sunday Night)
Issued at 1117 PM CST Sat Dec 20 2014

Focus will continue to be cigs thru the period. Guidance continues
to handle the current trends poorly across the region. Have
therefore continued low confidence in cig heights, but believe
overall trends are reflected in TAFs. Believe conditions will
remain largely as-is except UIN becoming MVFR in the next hour or so.
Cigs shud slowly lift Sun around Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing remains uncertain.


&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 210324
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
924 PM CST Sat Dec 20 2014

.UPDATE:
Issued at 924 PM CST Sat Dec 20 2014

Clouds are lingering over the entire CWA this evening and will
likely do so into the overnight hours as we are experiencing one
of the longest nights of the year. Latest satellite observations
has shown that low clouds are expanding slowly  eastward over
east central/southeast Illinois while there has been very little
movement over southeast Missouri. Latest ACARS sounding from KSTL
shows a decent inversion between 900-850mb with plenty of moisture
below it, and the RAP keeps plenty of low level moisture over the
CWA tonight, so left cloudy skies over the CWA the rest of the
night. Also raised temperatures tonight, particularly in the
southern and eastern counties where clearing was previously
forecast.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting yesterday. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 506 PM CST Sat Dec 20 2014

Focus will be cigs thru the period. Overall, guidance does not
have a good handle on the current trends across the region.
Therefore, have lower confidence in cig heights, but believe
overall trend is well reflected in TAFs. Believe conditions will
remain largely as-is except for CPS becoming MVFR in the next hour
or so. Guidance suggests that cigs at UIN/COU may also drop to IFR
late tonight into Sun morning. However, confidence is too low to
mention in TAF attm. Otherwise, cigs shud slowly lift Sun around
Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing is uncertain.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 210324
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
924 PM CST Sat Dec 20 2014

.UPDATE:
Issued at 924 PM CST Sat Dec 20 2014

Clouds are lingering over the entire CWA this evening and will
likely do so into the overnight hours as we are experiencing one
of the longest nights of the year. Latest satellite observations
has shown that low clouds are expanding slowly  eastward over
east central/southeast Illinois while there has been very little
movement over southeast Missouri. Latest ACARS sounding from KSTL
shows a decent inversion between 900-850mb with plenty of moisture
below it, and the RAP keeps plenty of low level moisture over the
CWA tonight, so left cloudy skies over the CWA the rest of the
night. Also raised temperatures tonight, particularly in the
southern and eastern counties where clearing was previously
forecast.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting yesterday. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 506 PM CST Sat Dec 20 2014

Focus will be cigs thru the period. Overall, guidance does not
have a good handle on the current trends across the region.
Therefore, have lower confidence in cig heights, but believe
overall trend is well reflected in TAFs. Believe conditions will
remain largely as-is except for CPS becoming MVFR in the next hour
or so. Guidance suggests that cigs at UIN/COU may also drop to IFR
late tonight into Sun morning. However, confidence is too low to
mention in TAF attm. Otherwise, cigs shud slowly lift Sun around
Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing is uncertain.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 210324
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
924 PM CST Sat Dec 20 2014

.UPDATE:
Issued at 924 PM CST Sat Dec 20 2014

Clouds are lingering over the entire CWA this evening and will
likely do so into the overnight hours as we are experiencing one
of the longest nights of the year. Latest satellite observations
has shown that low clouds are expanding slowly  eastward over
east central/southeast Illinois while there has been very little
movement over southeast Missouri. Latest ACARS sounding from KSTL
shows a decent inversion between 900-850mb with plenty of moisture
below it, and the RAP keeps plenty of low level moisture over the
CWA tonight, so left cloudy skies over the CWA the rest of the
night. Also raised temperatures tonight, particularly in the
southern and eastern counties where clearing was previously
forecast.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting yesterday. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 506 PM CST Sat Dec 20 2014

Focus will be cigs thru the period. Overall, guidance does not
have a good handle on the current trends across the region.
Therefore, have lower confidence in cig heights, but believe
overall trend is well reflected in TAFs. Believe conditions will
remain largely as-is except for CPS becoming MVFR in the next hour
or so. Guidance suggests that cigs at UIN/COU may also drop to IFR
late tonight into Sun morning. However, confidence is too low to
mention in TAF attm. Otherwise, cigs shud slowly lift Sun around
Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing is uncertain.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 210324
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
924 PM CST Sat Dec 20 2014

.UPDATE:
Issued at 924 PM CST Sat Dec 20 2014

Clouds are lingering over the entire CWA this evening and will
likely do so into the overnight hours as we are experiencing one
of the longest nights of the year. Latest satellite observations
has shown that low clouds are expanding slowly  eastward over
east central/southeast Illinois while there has been very little
movement over southeast Missouri. Latest ACARS sounding from KSTL
shows a decent inversion between 900-850mb with plenty of moisture
below it, and the RAP keeps plenty of low level moisture over the
CWA tonight, so left cloudy skies over the CWA the rest of the
night. Also raised temperatures tonight, particularly in the
southern and eastern counties where clearing was previously
forecast.

Britt

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting yesterday. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 506 PM CST Sat Dec 20 2014

Focus will be cigs thru the period. Overall, guidance does not
have a good handle on the current trends across the region.
Therefore, have lower confidence in cig heights, but believe
overall trend is well reflected in TAFs. Believe conditions will
remain largely as-is except for CPS becoming MVFR in the next hour
or so. Guidance suggests that cigs at UIN/COU may also drop to IFR
late tonight into Sun morning. However, confidence is too low to
mention in TAF attm. Otherwise, cigs shud slowly lift Sun around
Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing is uncertain.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 202313
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
513 PM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting ydy. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 506 PM CST Sat Dec 20 2014

Focus will be cigs thru the period. Overall, guidance does not
have a good handle on the current trends across the region.
Therefore, have lower confidence in cig heights, but believe
overall trend is well reflected in TAFs. Believe conditions will
remain largely as-is except for CPS becoming MVFR in the next hour
or so. Guidance suggests that cigs at UIN/COU may also drop to IFR
late tonight into Sun morning. However, confidence is too low to
mention in TAF attm. Otherwise, cigs shud slowly lift Sun around
Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing is uncertain.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 202313
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
513 PM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting ydy. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Sunday Evening)
Issued at 506 PM CST Sat Dec 20 2014

Focus will be cigs thru the period. Overall, guidance does not
have a good handle on the current trends across the region.
Therefore, have lower confidence in cig heights, but believe
overall trend is well reflected in TAFs. Believe conditions will
remain largely as-is except for CPS becoming MVFR in the next hour
or so. Guidance suggests that cigs at UIN/COU may also drop to IFR
late tonight into Sun morning. However, confidence is too low to
mention in TAF attm. Otherwise, cigs shud slowly lift Sun around
Noon or during the afternoon.

Specifics for KSTL: Expect cigs to remain in higher MVFR range
thru much of the forecast period with sely to ssely winds aob 10
kts. Believe cigs will lift to VFR Sun afternoon, however, exact
timing is uncertain.

Tilly

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 202116
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
316 PM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting ydy. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1145 AM CST Sat Dec 20 2014

Seeing some holes in the clouds today, some making their way
towards STL metro area. But for the most part continue to see MVFR
cigs most locations, though did add tempo mention of IFR cigs at
KUIN for a few hours this afternoon. Winds to persist from the
south through the forecast period.

Specifics for KSTL:
Seeing some holes in the clouds today, some making their way
towards STL metro area. But kept MVFR cigs for now. Winds to
persist from the south through the forecast period.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 202116
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
316 PM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 302 PM CST Sat Dec 20 2014

Clouds will persist early tonight and perhaps start to decrease
from south to north by morning. Overnight lows should be similar
to last night in most locations.

Kanofsky

.LONG TERM:  (Sunday through Next Saturday)
Issued at 302 PM CST Sat Dec 20 2014

The primary forecast issues revolve around a large low pressure
system and a deep trough which are expected to affect the area
between Mon and Wed.

The ongoing gradual warming trend (highs today were generally about
5 degrees warmer than yesterday, which in turn was a few degrees
warmer than the previous day) will persist on Sunday and Monday.
Monday`s highs in the mid-40s to lower 50s will be around 10
degrees above average for this time of year.

The aforementioned low pressure system develops over the northern
plains on Sunday and Sunday night, eventually closing off on Mon or
Mon night within a deep trough over the central CONUS. This system
will dominate our weather through Wed, and widespread rain is likely
as it moves into the region on Mon and Mon night. Forecast PW values
of between 0.6" and 0.8" by 00z Tue are above the 75th percentile
and approaching +2 SD for December. A cold front is expected to move
through parts of MO/IL on late Mon night or Tue morning, which is
slower timing than the models were predicting ydy. By Tue
afternoon or evening, some of the rain will probably switch over
to light snow within the colder post-frontal air mass.
Temperatures return to near or below average behind the front.

Meanwhile, a second vort max is forecast to drop into the central
CONUS trough and induce a new surface wave along the cold front
somewhere in TX/AR/LA (a third, smaller vort max interacts with
the northern upper low center during this time). The resulting
southern system then lifts northeastward on Tue and Tue night, but
there are sufficient differences between the GFS and ECMWF to
preclude getting more specific than SChc/Chc PoPs with a generic
rain/snow mix.

After the trough rotates away on Wed night or Thu, a brief period
of upper ridging is anticipated ahead of the next disturbance. The
12z runs of the ECMWF and GFS are in better agreement on the large
scale pattern compared to 24hrs ago, but the forecast with this
system will still depend on what will have happened with the
previous system, and confidence remains low.

Kanofsky

&&

.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1145 AM CST Sat Dec 20 2014

Seeing some holes in the clouds today, some making their way
towards STL metro area. But for the most part continue to see MVFR
cigs most locations, though did add tempo mention of IFR cigs at
KUIN for a few hours this afternoon. Winds to persist from the
south through the forecast period.

Specifics for KSTL:
Seeing some holes in the clouds today, some making their way
towards STL metro area. But kept MVFR cigs for now. Winds to
persist from the south through the forecast period.

Byrd

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 201746
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1146 AM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 320 AM CST Sat Dec 20 2014

Dirty ridge remains over the area today with abundant low level
moisture trapped beneath an inversion around 850mb.  Flurries are
currently falling at WFO LSX out here in Weldon Spring, so have
updated the forecast to include flurries along and west of the
Mississippi for a few hours this morning.  Forecast soundings
indicate that the lower atmosphere should warm sufficiently to
preclude any frozen precipitation by around 15Z, and weak low level
lift should be subsiding by mid-day as the upstream shortwave which
is currently over northwest MO/eastern NE moves into Illinois.  Was
a little too cool on yesterday`s highs...and today`s temperatures
may be tricky as well with variable cloud heights and thicknesses
across the region.  Used a blend of MOS guidance, but tried to lean
toward the warmer numbers except over northeast Missouri and west
central Illinois where clouds should generally be thicker allowing
for less insolation.

Carney

.LONG TERM:  (Tonight through Friday)
Issued at 320 AM CST Sat Dec 20 2014

(Tonight)

Southerly flow is expected to take some toll on the rather extensive
area of low clouds currently entrenched across the area.  The areas
that stand the best chance of seeing some clearing will be south and
east of STL metro and went cautiously optimistic with the forecast.
Any clearing should be short-lived with mid and high clouds
increasing heading into Sunday with the next system.

Prefered the warmer MET MOS for areas north and west of STL metro
where clouds should hang tough, but a MOS blend preferred for areas
in the south and east where some clearing looks likely.

(Sunday - Wednesday)

The beginnings of what will be a deep upper level TROF is expected
to develop later on Sunday over the central CONUS and then take at
least until Wednesday before finally shifting east.

An initial impulse will begin to lay the groundwork for this to
happen late Sunday night and Monday...with PoPs primarily confined
to the northern part of MO and central IL.  The highest PoPs were
reserved for Monday Night and Tuesday with a very favorable synoptic
setup with a more mature deep TROF, upstream, and a significant
impulse rotating around the base of the TROF.  Pcpn-types thru
Tuesday afternoon look to be all liquid, however.

Things begin to get interesting Tuesday night into Wednesday with
most model solutions closing the system off and with the cold air
thus generated from this closing off, the pcpn will turn to snow.
Where and when this system closes off will be critical.  The current
model consensus favors this to occur late Tuesday night almost
directly overhead of our region.  If this stands, snow will be
possible at the end of the event later on Tuesday night and
transition to snow showers Wednesday with light accums possible.
Something to watch closely...because...an earlier closing off and/or
a more western location for the closing off of the system (per the
DGEX and 06z NAM) would mean a substantial increase in snowfall
potential for parts of our area...such as what the consensus
solution currently shows for parts of eastern IL.

Temps will be at or above normal thru Tuesday, with a return to
below normal values on Christmas Eve in the wake of the system.

(Christmas)

Models continue to advertise a transitional pattern this day which
is a good sign for quiet wx with near seasonal temps.

(Friday)

Models all diverge significantly on how to handle the next system
and so very low confidence on not just PoPs but also pcpn-types with
a rather large spread in temp profiles.  A lot of how this pans out
will depend on exactly how the Tuesday-Wednesday system develops.

TES

&&

.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1145 AM CST Sat Dec 20 2014

Seeing some holes in the clouds today, some making their way
towards STL metro area. But for the most part continue to see MVFR
cigs most locations, though did add tempo mention of IFR cigs at
KUIN for a few hours this afternoon. Winds to persist from the
south through the forecast period.

Specifics for KSTL:
Seeing some holes in the clouds today, some making their way
towards STL metro area. But kept MVFR cigs for now. Winds to
persist from the south through the forecast period.

Byrd
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$
WFO LSX






000
FXUS63 KLSX 201746
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1146 AM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 320 AM CST Sat Dec 20 2014

Dirty ridge remains over the area today with abundant low level
moisture trapped beneath an inversion around 850mb.  Flurries are
currently falling at WFO LSX out here in Weldon Spring, so have
updated the forecast to include flurries along and west of the
Mississippi for a few hours this morning.  Forecast soundings
indicate that the lower atmosphere should warm sufficiently to
preclude any frozen precipitation by around 15Z, and weak low level
lift should be subsiding by mid-day as the upstream shortwave which
is currently over northwest MO/eastern NE moves into Illinois.  Was
a little too cool on yesterday`s highs...and today`s temperatures
may be tricky as well with variable cloud heights and thicknesses
across the region.  Used a blend of MOS guidance, but tried to lean
toward the warmer numbers except over northeast Missouri and west
central Illinois where clouds should generally be thicker allowing
for less insolation.

Carney

.LONG TERM:  (Tonight through Friday)
Issued at 320 AM CST Sat Dec 20 2014

(Tonight)

Southerly flow is expected to take some toll on the rather extensive
area of low clouds currently entrenched across the area.  The areas
that stand the best chance of seeing some clearing will be south and
east of STL metro and went cautiously optimistic with the forecast.
Any clearing should be short-lived with mid and high clouds
increasing heading into Sunday with the next system.

Prefered the warmer MET MOS for areas north and west of STL metro
where clouds should hang tough, but a MOS blend preferred for areas
in the south and east where some clearing looks likely.

(Sunday - Wednesday)

The beginnings of what will be a deep upper level TROF is expected
to develop later on Sunday over the central CONUS and then take at
least until Wednesday before finally shifting east.

An initial impulse will begin to lay the groundwork for this to
happen late Sunday night and Monday...with PoPs primarily confined
to the northern part of MO and central IL.  The highest PoPs were
reserved for Monday Night and Tuesday with a very favorable synoptic
setup with a more mature deep TROF, upstream, and a significant
impulse rotating around the base of the TROF.  Pcpn-types thru
Tuesday afternoon look to be all liquid, however.

Things begin to get interesting Tuesday night into Wednesday with
most model solutions closing the system off and with the cold air
thus generated from this closing off, the pcpn will turn to snow.
Where and when this system closes off will be critical.  The current
model consensus favors this to occur late Tuesday night almost
directly overhead of our region.  If this stands, snow will be
possible at the end of the event later on Tuesday night and
transition to snow showers Wednesday with light accums possible.
Something to watch closely...because...an earlier closing off and/or
a more western location for the closing off of the system (per the
DGEX and 06z NAM) would mean a substantial increase in snowfall
potential for parts of our area...such as what the consensus
solution currently shows for parts of eastern IL.

Temps will be at or above normal thru Tuesday, with a return to
below normal values on Christmas Eve in the wake of the system.

(Christmas)

Models continue to advertise a transitional pattern this day which
is a good sign for quiet wx with near seasonal temps.

(Friday)

Models all diverge significantly on how to handle the next system
and so very low confidence on not just PoPs but also pcpn-types with
a rather large spread in temp profiles.  A lot of how this pans out
will depend on exactly how the Tuesday-Wednesday system develops.

TES

&&

.AVIATION:  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1145 AM CST Sat Dec 20 2014

Seeing some holes in the clouds today, some making their way
towards STL metro area. But for the most part continue to see MVFR
cigs most locations, though did add tempo mention of IFR cigs at
KUIN for a few hours this afternoon. Winds to persist from the
south through the forecast period.

Specifics for KSTL:
Seeing some holes in the clouds today, some making their way
towards STL metro area. But kept MVFR cigs for now. Winds to
persist from the south through the forecast period.

Byrd
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$
WFO LSX







000
FXUS63 KLSX 201203
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
603 AM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 320 AM CST Sat Dec 20 2014

Dirty ridge remains over the area today with abundant low level
moisture trapped beneath an inversion around 850mb.  Flurries are
currently falling at WFO LSX out here in Weldon Spring, so have
updated the forecast to include flurries along and west of the
Mississippi for a few hours this morning.  Forecast soundings
indicate that the lower atmosphere should warm sufficiently to
preclude any frozen precipitation by around 15Z, and weak low level
lift should be subsiding by mid-day as the upstream shortwave which
is currently over northwest MO/eastern NE moves into Illinois.  Was
a little too cool on yesterday`s highs...and today`s temperatures
may be tricky as well with variable cloud heights and thicknesses
across the region.  Used a blend of MOS guidance, but tried to lean
toward the warmer numbers except over northeast Missouri and west
central Illinois where clouds should generally be thicker allowing
for less insolation.

Carney

.LONG TERM:  (Tonight through Friday)
Issued at 320 AM CST Sat Dec 20 2014

(Tonight)

Southerly flow is expected to take some toll on the rather extensive
area of low clouds currently entrenched across the area.  The areas
that stand the best chance of seeing some clearing will be south and
east of STL metro and went cautiously optimistic with the forecast.
Any clearing should be short-lived with mid and high clouds
increasing heading into Sunday with the next system.

Prefered the warmer MET MOS for areas north and west of STL metro
where clouds should hang tough, but a MOS blend preferred for areas
in the south and east where some clearing looks likely.

(Sunday - Wednesday)

The beginnings of what will be a deep upper level TROF is expected
to develop later on Sunday over the central CONUS and then take at
least until Wednesday before finally shifting east.

An initial impulse will begin to lay the groundwork for this to
happen late Sunday night and Monday...with PoPs primarily confined
to the northern part of MO and central IL.  The highest PoPs were
reserved for Monday Night and Tuesday with a very favorable synoptic
setup with a more mature deep TROF, upstream, and a significant
impulse rotating around the base of the TROF.  Pcpn-types thru
Tuesday afternoon look to be all liquid, however.

Things begin to get interesting Tuesday night into Wednesday with
most model solutions closing the system off and with the cold air
thus generated from this closing off, the pcpn will turn to snow.
Where and when this system closes off will be critical.  The current
model consensus favors this to occur late Tuesday night almost
directly overhead of our region.  If this stands, snow will be
possible at the end of the event later on Tuesday night and
transition to snow showers Wednesday with light accums possible.
Something to watch closely...because...an earlier closing off and/or
a more western location for the closing off of the system (per the
DGEX and 06z NAM) would mean a substantial increase in snowfall
potential for parts of our area...such as what the consensus
solution currently shows for parts of eastern IL.

Temps will be at or above normal thru Tuesday, with a return to
below normal values on Christmas Eve in the wake of the system.

(Christmas)

Models continue to advertise a transitional pattern this day which
is a good sign for quiet wx with near seasonal temps.

(Friday)

Models all diverge significantly on how to handle the next system
and so very low confidence on not just PoPs but also pcpn-types with
a rather large spread in temp profiles.  A lot of how this pans out
will depend on exactly how the Tuesday-Wednesday system develops.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Sunday Morning)
Issued at 539 AM CST Sat Dec 20 2014

MVFR and IFR flight conditions prevail along and west of the
Mississippi River this morning...with the lowest ceilings over
central and northeast Missouri. Generally VFR ceilings prevail
over southwest Illinois. Expect ceilings to improve slowly through
the day, but it`s doubtful that ceilings will improve much beyond
broken-overcast 2000FT along and west of the Mississippi. Further
east over southwest Illinois there may be some initial dips into
MVFR territory, but it seems likely that VFR ceilings AOA 4000FT
will prevail for most of the day and into tonight.

Some guidance is hinting at rising ceilings tonight across the area;
however this seems unlikely given the time of year and current weather
pattern.

Specifics for KSTL:

Expect MVFR ceilings to prevail at Lambert today. Ceilings below
2000FT are just to the southwest of the STL Metro area, and should
be building toward the terminal over the next couple of hours.
Will see slow improvement through the day, but I think it`s
unlikely ceilings will rise above 3000FT through the end of the
TAF period.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 201203
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
603 AM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 320 AM CST Sat Dec 20 2014

Dirty ridge remains over the area today with abundant low level
moisture trapped beneath an inversion around 850mb.  Flurries are
currently falling at WFO LSX out here in Weldon Spring, so have
updated the forecast to include flurries along and west of the
Mississippi for a few hours this morning.  Forecast soundings
indicate that the lower atmosphere should warm sufficiently to
preclude any frozen precipitation by around 15Z, and weak low level
lift should be subsiding by mid-day as the upstream shortwave which
is currently over northwest MO/eastern NE moves into Illinois.  Was
a little too cool on yesterday`s highs...and today`s temperatures
may be tricky as well with variable cloud heights and thicknesses
across the region.  Used a blend of MOS guidance, but tried to lean
toward the warmer numbers except over northeast Missouri and west
central Illinois where clouds should generally be thicker allowing
for less insolation.

Carney

.LONG TERM:  (Tonight through Friday)
Issued at 320 AM CST Sat Dec 20 2014

(Tonight)

Southerly flow is expected to take some toll on the rather extensive
area of low clouds currently entrenched across the area.  The areas
that stand the best chance of seeing some clearing will be south and
east of STL metro and went cautiously optimistic with the forecast.
Any clearing should be short-lived with mid and high clouds
increasing heading into Sunday with the next system.

Prefered the warmer MET MOS for areas north and west of STL metro
where clouds should hang tough, but a MOS blend preferred for areas
in the south and east where some clearing looks likely.

(Sunday - Wednesday)

The beginnings of what will be a deep upper level TROF is expected
to develop later on Sunday over the central CONUS and then take at
least until Wednesday before finally shifting east.

An initial impulse will begin to lay the groundwork for this to
happen late Sunday night and Monday...with PoPs primarily confined
to the northern part of MO and central IL.  The highest PoPs were
reserved for Monday Night and Tuesday with a very favorable synoptic
setup with a more mature deep TROF, upstream, and a significant
impulse rotating around the base of the TROF.  Pcpn-types thru
Tuesday afternoon look to be all liquid, however.

Things begin to get interesting Tuesday night into Wednesday with
most model solutions closing the system off and with the cold air
thus generated from this closing off, the pcpn will turn to snow.
Where and when this system closes off will be critical.  The current
model consensus favors this to occur late Tuesday night almost
directly overhead of our region.  If this stands, snow will be
possible at the end of the event later on Tuesday night and
transition to snow showers Wednesday with light accums possible.
Something to watch closely...because...an earlier closing off and/or
a more western location for the closing off of the system (per the
DGEX and 06z NAM) would mean a substantial increase in snowfall
potential for parts of our area...such as what the consensus
solution currently shows for parts of eastern IL.

Temps will be at or above normal thru Tuesday, with a return to
below normal values on Christmas Eve in the wake of the system.

(Christmas)

Models continue to advertise a transitional pattern this day which
is a good sign for quiet wx with near seasonal temps.

(Friday)

Models all diverge significantly on how to handle the next system
and so very low confidence on not just PoPs but also pcpn-types with
a rather large spread in temp profiles.  A lot of how this pans out
will depend on exactly how the Tuesday-Wednesday system develops.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Sunday Morning)
Issued at 539 AM CST Sat Dec 20 2014

MVFR and IFR flight conditions prevail along and west of the
Mississippi River this morning...with the lowest ceilings over
central and northeast Missouri. Generally VFR ceilings prevail
over southwest Illinois. Expect ceilings to improve slowly through
the day, but it`s doubtful that ceilings will improve much beyond
broken-overcast 2000FT along and west of the Mississippi. Further
east over southwest Illinois there may be some initial dips into
MVFR territory, but it seems likely that VFR ceilings AOA 4000FT
will prevail for most of the day and into tonight.

Some guidance is hinting at rising ceilings tonight across the area;
however this seems unlikely given the time of year and current weather
pattern.

Specifics for KSTL:

Expect MVFR ceilings to prevail at Lambert today. Ceilings below
2000FT are just to the southwest of the STL Metro area, and should
be building toward the terminal over the next couple of hours.
Will see slow improvement through the day, but I think it`s
unlikely ceilings will rise above 3000FT through the end of the
TAF period.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 200920
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
320 AM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 320 AM CST Sat Dec 20 2014

Dirty ridge remains over the area today with abundant low level
moisture trapped beneath an inversion around 850mb.  Flurries are
currently falling at WFO LSX out here in Weldon Spring, so have
updated the forecast to include flurries along and west of the
Mississippi for a few hours this morning.  Forecast soundings
indicate that the lower atmosphere should warm sufficiently to
preclude any frozen precipitation by around 15Z, and weak low level
lift should be subsiding by mid-day as the upstream shortwave which
is currently over northwest MO/eastern NE moves into Illinois.  Was
a little too cool on yesterday`s highs...and today`s temperatures
may be tricky as well with variable cloud heights and thicknesses
across the region.  Used a blend of MOS guidance, but tried to lean
toward the warmer numbers except over northeast Missouri and west
central Illinois where clouds should generally be thicker allowing
for less insolation.

Carney

.LONG TERM:  (Tonight through Friday)
Issued at 320 AM CST Sat Dec 20 2014

(Tonight)

Southerly flow is expected to take some toll on the rather extensive
area of low clouds currently entrenched across the area.  The areas
that stand the best chance of seeing some clearing will be south and
east of STL metro and went cautiously optimistic with the forecast.
Any clearing should be short-lived with mid and high clouds
increasing heading into Sunday with the next system.

Prefered the warmer MET MOS for areas north and west of STL metro
where clouds should hang tough, but a MOS blend preferred for areas
in the south and east where some clearing looks likely.

(Sunday - Wednesday)

The beginnings of what will be a deep upper level TROF is expected
to develop later on Sunday over the central CONUS and then take at
least until Wednesday before finally shifting east.

An initial impulse will begin to lay the groundwork for this to
happen late Sunday night and Monday...with PoPs primarily confined
to the northern part of MO and central IL.  The highest PoPs were
reserved for Monday Night and Tuesday with a very favorable synoptic
setup with a more mature deep TROF, upstream, and a significant
impulse rotating around the base of the TROF.  Pcpn-types thru
Tuesday afternoon look to be all liquid, however.

Things begin to get interesting Tuesday night into Wednesday with
most model solutions closing the system off and with the cold air
thus generated from this closing off, the pcpn will turn to snow.
Where and when this system closes off will be critical.  The current
model consensus favors this to occur late Tuesday night almost
directly overhead of our region.  If this stands, snow will be
possible at the end of the event later on Tuesday night and
transition to snow showers Wednesday with light accums possible.
Something to watch closely...because...an earlier closing off and/or
a more western location for the closing off of the system (per the
DGEX and 06z NAM) would mean a substantial increase in snowfall
potential for parts of our area...such as what the consensus
solution currently shows for parts of eastern IL.

Temps will be at or above normal thru Tuesday, with a return to
below normal values on Christmas Eve in the wake of the system.

(Christmas)

Models continue to advertise a transitional pattern this day which
is a good sign for quiet wx with near seasonal temps.

(Friday)

Models all diverge significantly on how to handle the next system
and so very low confidence on not just PoPs but also pcpn-types with
a rather large spread in temp profiles.  A lot of how this pans out
will depend on exactly how the Tuesday-Wednesday system develops.

TES

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1119 PM CST Fri Dec 19 2014

VFR conditions have persisted through the evening hours at KUIN
and the St. Louis metro TAF sites because of drier air moving in
from the east. MVFR conditions are expected to move into these TAF
sites between 06-09Z as large area of lower ceilings over the
western two-thirds of Missouri expands eastward overnight. Still
expect visibilities to fall to 2SM at KSUS which lies in the
Missouri river valley. These MVFR and IFR conditions will then
likely persist through the morning hours before there is some
improvement by early afternoon. Also, some patchy drizzle or
freezing drizzle is possible at KCOU and KUIN between 09-15Z,
though chances are too low to include in the TAF.

Specifics for KSTL: Expect MFVR conditions to move into the
terminal by 08Z as large area of MVFR ceilings to the west of the
terminal expands eastward. Expect these conditions to last through
at least midday on Saturday.

Britt

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     44  32  46  35 /   5   5   5  10
Quincy          38  32  43  35 /  10  10   5  10
Columbia        42  33  44  37 /  10  10   5  20
Jefferson City  44  34  46  37 /  10   5   5  20
Salem           40  29  44  33 /   5   0   5   5
Farmington      43  30  46  35 /   5   0   5   5

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX






000
FXUS63 KLSX 200920
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
320 AM CST Sat Dec 20 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 320 AM CST Sat Dec 20 2014

Dirty ridge remains over the area today with abundant low level
moisture trapped beneath an inversion around 850mb.  Flurries are
currently falling at WFO LSX out here in Weldon Spring, so have
updated the forecast to include flurries along and west of the
Mississippi for a few hours this morning.  Forecast soundings
indicate that the lower atmosphere should warm sufficiently to
preclude any frozen precipitation by around 15Z, and weak low level
lift should be subsiding by mid-day as the upstream shortwave which
is currently over northwest MO/eastern NE moves into Illinois.  Was
a little too cool on yesterday`s highs...and today`s temperatures
may be tricky as well with variable cloud heights and thicknesses
across the region.  Used a blend of MOS guidance, but tried to lean
toward the warmer numbers except over northeast Missouri and west
central Illinois where clouds should generally be thicker allowing
for less insolation.

Carney

.LONG TERM:  (Tonight through Friday)
Issued at 320 AM CST Sat Dec 20 2014

(Tonight)

Southerly flow is expected to take some toll on the rather extensive
area of low clouds currently entrenched across the area.  The areas
that stand the best chance of seeing some clearing will be south and
east of STL metro and went cautiously optimistic with the forecast.
Any clearing should be short-lived with mid and high clouds
increasing heading into Sunday with the next system.

Prefered the warmer MET MOS for areas north and west of STL metro
where clouds should hang tough, but a MOS blend preferred for areas
in the south and east where some clearing looks likely.

(Sunday - Wednesday)

The beginnings of what will be a deep upper level TROF is expected
to develop later on Sunday over the central CONUS and then take at
least until Wednesday before finally shifting east.

An initial impulse will begin to lay the groundwork for this to
happen late Sunday night and Monday...with PoPs primarily confined
to the northern part of MO and central IL.  The highest PoPs were
reserved for Monday Night and Tuesday with a very favorable synoptic
setup with a more mature deep TROF, upstream, and a significant
impulse rotating around the base of the TROF.  Pcpn-types thru
Tuesday afternoon look to be all liquid, however.

Things begin to get interesting Tuesday night into Wednesday with
most model solutions closing the system off and with the cold air
thus generated from this closing off, the pcpn will turn to snow.
Where and when this system closes off will be critical.  The current
model consensus favors this to occur late Tuesday night almost
directly overhead of our region.  If this stands, snow will be
possible at the end of the event later on Tuesday night and
transition to snow showers Wednesday with light accums possible.
Something to watch closely...because...an earlier closing off and/or
a more western location for the closing off of the system (per the
DGEX and 06z NAM) would mean a substantial increase in snowfall
potential for parts of our area...such as what the consensus
solution currently shows for parts of eastern IL.

Temps will be at or above normal thru Tuesday, with a return to
below normal values on Christmas Eve in the wake of the system.

(Christmas)

Models continue to advertise a transitional pattern this day which
is a good sign for quiet wx with near seasonal temps.

(Friday)

Models all diverge significantly on how to handle the next system
and so very low confidence on not just PoPs but also pcpn-types with
a rather large spread in temp profiles.  A lot of how this pans out
will depend on exactly how the Tuesday-Wednesday system develops.

TES

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1119 PM CST Fri Dec 19 2014

VFR conditions have persisted through the evening hours at KUIN
and the St. Louis metro TAF sites because of drier air moving in
from the east. MVFR conditions are expected to move into these TAF
sites between 06-09Z as large area of lower ceilings over the
western two-thirds of Missouri expands eastward overnight. Still
expect visibilities to fall to 2SM at KSUS which lies in the
Missouri river valley. These MVFR and IFR conditions will then
likely persist through the morning hours before there is some
improvement by early afternoon. Also, some patchy drizzle or
freezing drizzle is possible at KCOU and KUIN between 09-15Z,
though chances are too low to include in the TAF.

Specifics for KSTL: Expect MFVR conditions to move into the
terminal by 08Z as large area of MVFR ceilings to the west of the
terminal expands eastward. Expect these conditions to last through
at least midday on Saturday.

Britt

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     44  32  46  35 /   5   5   5  10
Quincy          38  32  43  35 /  10  10   5  10
Columbia        42  33  44  37 /  10  10   5  20
Jefferson City  44  34  46  37 /  10   5   5  20
Salem           40  29  44  33 /   5   0   5   5
Farmington      43  30  46  35 /   5   0   5   5

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





000
FXUS63 KLSX 200536
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1136 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 734 PM CST Fri Dec 19 2014

Fog was starting to develop over western MO this evening. Although
no drizzle has been reported yet across our area, conditions will
remain favorable for fog and light drizzle overnight. The going
forecast looks on track with only minor adjustments required.
Updated grids and products have been sent.

Kanofsky

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1119 PM CST Fri Dec 19 2014

VFR conditions have persisted through the evening hours at KUIN
and the St. Louis metro TAF sites because of drier air moving in
from the east. MVFR conditions are expected to move into these TAF
sites between 06-09Z as large area of lower ceilings over the
western two-thirds of Missouri expands eastward overnight. Still
expect visibilities to fall to 2SM at KSUS which lies in the
Missouri river valley. These MVFR and IFR conditions will then
likely persist through the morning hours before there is some
improvement by early afternoon. Also, some patchy drizzle or
freezing drizzle is possible at KCOU and KUIN between 09-15Z,
though chances are too low to include in the TAF.

Specifics for KSTL: Expect MFVR conditions to move into the
terminal by 08Z as large area of MVFR ceilings to the west of the
terminal expands eastward. Expect these conditions to last through
at least midday on Saturday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 200536
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1136 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 734 PM CST Fri Dec 19 2014

Fog was starting to develop over western MO this evening. Although
no drizzle has been reported yet across our area, conditions will
remain favorable for fog and light drizzle overnight. The going
forecast looks on track with only minor adjustments required.
Updated grids and products have been sent.

Kanofsky

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1119 PM CST Fri Dec 19 2014

VFR conditions have persisted through the evening hours at KUIN
and the St. Louis metro TAF sites because of drier air moving in
from the east. MVFR conditions are expected to move into these TAF
sites between 06-09Z as large area of lower ceilings over the
western two-thirds of Missouri expands eastward overnight. Still
expect visibilities to fall to 2SM at KSUS which lies in the
Missouri river valley. These MVFR and IFR conditions will then
likely persist through the morning hours before there is some
improvement by early afternoon. Also, some patchy drizzle or
freezing drizzle is possible at KCOU and KUIN between 09-15Z,
though chances are too low to include in the TAF.

Specifics for KSTL: Expect MFVR conditions to move into the
terminal by 08Z as large area of MVFR ceilings to the west of the
terminal expands eastward. Expect these conditions to last through
at least midday on Saturday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 200154
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
754 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 734 PM CST Fri Dec 19 2014

Fog was starting to develop over western MO this evening. Although
no drizzle has been reported yet across our area, conditions will
remain favorable for fog and light drizzle overnight. The going
forecast looks on track with only minor adjustments required.
Updated grids and products have been sent.

Kanofsky

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Saturday Evening)
Issued at 559 PM CST Fri Dec 19 2014

Extensive area of MVFR and IFR conditions across the western two
thirds of Missouri will expand eastward later this evening,
reaching the St. Louis metro TAF sites and KUIN between 04-06Z.
Then expect IFR ceilings to develop overnight at KCOU and KUIN.
Still expect 2SM visibilities to reach KSUS in the Missouri river
valley. Think just MVFR conditions will occur at KSTL and KCPS.
These conditions will then likely persist through the morning
hours before there is some improvement by early afternoon.

Specifics for KSTL: Believe going TAF has a good handle on current
situation as a dry easterly wind will likely keep conditions VFR
this evening. Then expect MVFR ceilings that are currently just
west of the terminal to move into KSTL overnight and persist
through Saturday morning with ceilings rising above 2000ft by
midday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 200154
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
754 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 734 PM CST Fri Dec 19 2014

Fog was starting to develop over western MO this evening. Although
no drizzle has been reported yet across our area, conditions will
remain favorable for fog and light drizzle overnight. The going
forecast looks on track with only minor adjustments required.
Updated grids and products have been sent.

Kanofsky

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Saturday Evening)
Issued at 559 PM CST Fri Dec 19 2014

Extensive area of MVFR and IFR conditions across the western two
thirds of Missouri will expand eastward later this evening,
reaching the St. Louis metro TAF sites and KUIN between 04-06Z.
Then expect IFR ceilings to develop overnight at KCOU and KUIN.
Still expect 2SM visibilities to reach KSUS in the Missouri river
valley. Think just MVFR conditions will occur at KSTL and KCPS.
These conditions will then likely persist through the morning
hours before there is some improvement by early afternoon.

Specifics for KSTL: Believe going TAF has a good handle on current
situation as a dry easterly wind will likely keep conditions VFR
this evening. Then expect MVFR ceilings that are currently just
west of the terminal to move into KSTL overnight and persist
through Saturday morning with ceilings rising above 2000ft by
midday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 200154
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
754 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 734 PM CST Fri Dec 19 2014

Fog was starting to develop over western MO this evening. Although
no drizzle has been reported yet across our area, conditions will
remain favorable for fog and light drizzle overnight. The going
forecast looks on track with only minor adjustments required.
Updated grids and products have been sent.

Kanofsky

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Saturday Evening)
Issued at 559 PM CST Fri Dec 19 2014

Extensive area of MVFR and IFR conditions across the western two
thirds of Missouri will expand eastward later this evening,
reaching the St. Louis metro TAF sites and KUIN between 04-06Z.
Then expect IFR ceilings to develop overnight at KCOU and KUIN.
Still expect 2SM visibilities to reach KSUS in the Missouri river
valley. Think just MVFR conditions will occur at KSTL and KCPS.
These conditions will then likely persist through the morning
hours before there is some improvement by early afternoon.

Specifics for KSTL: Believe going TAF has a good handle on current
situation as a dry easterly wind will likely keep conditions VFR
this evening. Then expect MVFR ceilings that are currently just
west of the terminal to move into KSTL overnight and persist
through Saturday morning with ceilings rising above 2000ft by
midday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 200154
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
754 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 734 PM CST Fri Dec 19 2014

Fog was starting to develop over western MO this evening. Although
no drizzle has been reported yet across our area, conditions will
remain favorable for fog and light drizzle overnight. The going
forecast looks on track with only minor adjustments required.
Updated grids and products have been sent.

Kanofsky

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Saturday Evening)
Issued at 559 PM CST Fri Dec 19 2014

Extensive area of MVFR and IFR conditions across the western two
thirds of Missouri will expand eastward later this evening,
reaching the St. Louis metro TAF sites and KUIN between 04-06Z.
Then expect IFR ceilings to develop overnight at KCOU and KUIN.
Still expect 2SM visibilities to reach KSUS in the Missouri river
valley. Think just MVFR conditions will occur at KSTL and KCPS.
These conditions will then likely persist through the morning
hours before there is some improvement by early afternoon.

Specifics for KSTL: Believe going TAF has a good handle on current
situation as a dry easterly wind will likely keep conditions VFR
this evening. Then expect MVFR ceilings that are currently just
west of the terminal to move into KSTL overnight and persist
through Saturday morning with ceilings rising above 2000ft by
midday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 192359
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
559 PM CST Fri Dec 19 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Saturday Evening)
Issued at 559 PM CST Fri Dec 19 2014

Extensive area of MVFR and IFR conditions across the western two
thirds of Missouri will expand eastward later this evening,
reaching the St. Louis metro TAF sites and KUIN between 04-06Z.
Then expect IFR ceilings to develop overnight at KCOU and KUIN.
Still expect 2SM visibilities to reach KSUS in the Missouri river
valley. Think just MVFR conditions will occur at KSTL and KCPS.
These conditions will then likely persist through the morning
hours before there is some improvement by early afternoon.

Specifics for KSTL: Believe going TAF has a good handle on current
situation as a dry easterly wind will likely keep conditions VFR
this evening. Then expect MVFR ceilings that are currently just
west of the terminal to move into KSTL overnight and persist
through Saturday morning with ceilings rising above 2000ft by
midday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 192359
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
559 PM CST Fri Dec 19 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 00z TAFs through 00z Saturday Evening)
Issued at 559 PM CST Fri Dec 19 2014

Extensive area of MVFR and IFR conditions across the western two
thirds of Missouri will expand eastward later this evening,
reaching the St. Louis metro TAF sites and KUIN between 04-06Z.
Then expect IFR ceilings to develop overnight at KCOU and KUIN.
Still expect 2SM visibilities to reach KSUS in the Missouri river
valley. Think just MVFR conditions will occur at KSTL and KCPS.
These conditions will then likely persist through the morning
hours before there is some improvement by early afternoon.

Specifics for KSTL: Believe going TAF has a good handle on current
situation as a dry easterly wind will likely keep conditions VFR
this evening. Then expect MVFR ceilings that are currently just
west of the terminal to move into KSTL overnight and persist
through Saturday morning with ceilings rising above 2000ft by
midday.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 192115
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
315 PM CST Fri Dec 19 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1155 AM CST Fri Dec 19 2014

Pocket of low level dry air on the IL side of the Mississippi
River continue to make for tricky aviation forecasts. Will
primarily go with MVFR cigs from 1.5-3kft this afternoon, although
its possible that sites along the river (KUIN and STL metro TAFs)
may be on the fringes of this cloud deck. Wedge of dry air is
forecast to hold firm tonight, and while it appears likely that
IFR fog and stratus will once again form over COU in the deeper
low level moisture, trend is less clear cut for sites along the
river. It`s interesting that most guidance isn`t as bullish as
yesterday with IFR development at UIN and STL metro, in spite of
the fact that low level flow does become a bit more southerly
during the predawn hours (albeit weakly so). So, for these
locations have headed towards lower end MVFR cigs/vsbys during the
predawn hours, with the expectation that the primary IFR deck will
remain just west of the MSRVR.

Specifics for KSTL: As mentioned above, area will be on the
western fringes of a pocket of drier low level air over IL. Have
generally gone with bkn MVFR cloud deck through 06z to try to
reflect this, but a slight shift in the edge of this moisture
could mean more or less cloudiness in the MVFR range. Forecast
hints at some lower vsbys and cloudiness during the predawn hours,
but based on the preponderence of guidance have maintained
prevailing ceiling and vsbys in the MVFR range.

Truett

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 192115
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
315 PM CST Fri Dec 19 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 309 PM CST Fri Dec 19 2014

Shortwave energizing southern stream system over the Gulf Coast is
spreading some mid and high level cloudiness across our region
this afternoon. Regional radar mosaic is indicating some very
light echoes associated with this cloud deck slowly working their
way from n AR into se MO, so will continue the mention of flurries
in our far southeast counties into the early evening hours.

Otherwise, broad area of low level moisture remains locked on SW
periphery of the surface ridge that stretches from the Great Lakes
into the lower Ohio Valley, and this low level moisture should
keep skies cloudy over most of the region even after the passage
of the aforementioned shortwave. A secondary shortwave is progged
to drop from the mid MO Valley after midnight tonight, producing
some weak low level WAA advection over western sections of the
CWA. However, forecast sounding suggest that moisture will remain
stratified in the lowest few thousand feet of the AMS with very
little moisture in layer that would allow for ice nuclei to form.
Therefore, any precip associated with the broad area of lift and
WAA would likely be in the form of drizzle, much as suggested by
going forecasts. Temperatures aren`t expected to drop more than a
few degrees from their current levels, but latest forecast of
hourly temp trends suggest that some freezing drizzle will be
possible in northern parts of the FA, primarily along and north of
a Shelbina-Bowling Green line. Relatively warm ground temps (MO Ag
site at Novelty has 2-4" soil temps between 32-35) and road
treatments from yesterday`s light snowfall should mitigate most
problems if freezing drizzle does form, but obviously we will be
monitoring this threat.

Truett

.LONG TERM:  (Saturday through Next Friday)
Issued at 309 PM CST Fri Dec 19 2014

Expect quiet weather this weekend with a gradual warming trend
from Saturday through Monday. A compact vort max moving from IA
into IL on Saturday might support light drizzle during the morning
hours.

Precipitation chances increase on Sunday night into Monday ahead of
a clipper-like system which will be developing over the northern
plains and eventually closing off over the central or eastern CONUS.
This system will probably bring periods of rain to the area from
Monday through Tuesday, especially on Monday (central MO) and
Monday night (eastern MO and western IL). Cooler temperatures are
expected behind Monday night`s cold front, and this may cause the
rain to mix with snow at times. Light snow could linger into
Wednesday, depending on how quickly the system moves away from the
area.

A brief period of shortwave ridging is anticipated during the middle
to late part of the week ahead of a developing low pressure system
which could bring widespread rain/snow to the area next
Friday/Friday night. The model solutions which depict low pressure
systems at these extended time ranges often undergo several
changes, therefore there is low confidence in the timing/location
of any precipitation for late next week.

Kanofsky

&&

.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1155 AM CST Fri Dec 19 2014

Pocket of low level dry air on the IL side of the Mississippi
River continue to make for tricky aviation forecasts. Will
primarily go with MVFR cigs from 1.5-3kft this afternoon, although
its possible that sites along the river (KUIN and STL metro TAFs)
may be on the fringes of this cloud deck. Wedge of dry air is
forecast to hold firm tonight, and while it appears likely that
IFR fog and stratus will once again form over COU in the deeper
low level moisture, trend is less clear cut for sites along the
river. It`s interesting that most guidance isn`t as bullish as
yesterday with IFR development at UIN and STL metro, in spite of
the fact that low level flow does become a bit more southerly
during the predawn hours (albeit weakly so). So, for these
locations have headed towards lower end MVFR cigs/vsbys during the
predawn hours, with the expectation that the primary IFR deck will
remain just west of the MSRVR.

Specifics for KSTL: As mentioned above, area will be on the
western fringes of a pocket of drier low level air over IL. Have
generally gone with bkn MVFR cloud deck through 06z to try to
reflect this, but a slight shift in the edge of this moisture
could mean more or less cloudiness in the MVFR range. Forecast
hints at some lower vsbys and cloudiness during the predawn hours,
but based on the preponderence of guidance have maintained
prevailing ceiling and vsbys in the MVFR range.

Truett

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 191803
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1203 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 1155 AM CST Fri Dec 19 2014

A few tweaks to going forecast...primarily to adjust chaotic cloud
cover over our IL counties and to raise temps there a degree or
two due to a bit more sun. Other change has been to pull mention
of drizzle over mid MO for this afternoon as stratus has
temporarily lifted here. However, did continue mention of flurries
over our se MO counties as very light echoes on n fringes of s
system showing up over nw AR, and heading to the NE.

Truett

&&

.SHORT TERM:  (Through Late This Afternoon)
Issued at 300 AM CST Fri Dec 19 2014

A weak ridge of high pressure which extends from the Great Lakes
region south through the Mid-Mississippi Valley is in control of our
weather today.  Soundings are showing plenty of low level moisture
trapped under an inversion at around 850mb.  The vertical structure
of the atmosphere is much like what we had last weekend with the
moisture stratified in the low levels, so I don`t expect much
sunshine for the majority of the area...with the possible exception
of south central and extreme southwest Illinois.  Some drier air is
trying to drift in on weak easterly low level flow.  Vertical cross
sections show intermittent weak upward motion through the day,
primarily over central Missouri, and short term guidance spits out a
hundredth of QPF here and there.  Additionally, the HRRR shows some
weak simulated radar echos over parts of central and southeast
Missouri today, so have added in a little patchy drizzle to the
forecast.

Carney

.LONG TERM:  (Tonight through Thursday)
Issued at 300 AM CST Fri Dec 19 2014

(Tonight - Saturday)

The brunt of a storm system is expected to pass relatively unnoticed
to our south this evening, and if it weren`t for some interaction
with a more northerly component, would probably result in no
precipitation anywhere, but such as it is, some very light snow
looks to be possible early this evening for an area primarily south
of STL metro.  This arrangement should be short-lived, with much of
the mid and upper level moisture quickly being shunted off to the
east, leaving behind extensive low cloud cover.  At this point,
there is good model consensus on a weak WAA, convergence regime
setting up at the low levels that noses into central MO by midnight
tonight and then snaking its way northward towards the UIN area by
Saturday morning.  Have added in patchy drizzle as a result.  For
now, expecting influence of the surface RIDGE to trump this for STL
metro and areas S and E.  Temps will probably not go very far
tonight with clouds hanging tough, although where the surface RIDGE
is dominant, should see a steady but slow drop...but for areas to
the N and W of STL metro where a light S flow will persist, near
steady temps are expected.  Speaking of temps, especially to the N
and W of STL metro where drizzle is expected to develop, readings
will be within a degree or two of the freezing mark and so this will
probably manifest more as patchy FZDZ for areas in northeast MO and
west-central IL.  Prefer the lower MOS temps for Saturday maxes
given cloud cover expected, but they should still rebound into the
upper 30s and low 40s.

(Sunday - Wednesday)

A rather deep upper level TROF is expected to develop later on
Sunday over the central CONUS and then take a good part of the week
before finally shifting east.  Maintained the highest PoPs for
Monday thru Tuesday, where there is good model consensus on when the
TROF will be close enough, yet its axis still just upstream...and
then reduce to slight chances by Wednesday when the TROF axis by
this time will have shifted to the east.

While much of the precipitation will be just rain, especially on the
front-end, enough cold air starts working in on Tuesday, especially
aloft, that will allow the atmosphere to sustain a changeover to
snow.  The only limiting factor at this point will be surface and/or
boundary layer temps that will ultimately determine the rain vs.
snow question.  GFS and EC MOS surface temps suggest this will not
happen for most locales until late in the day on Tuesday with snow
then expected as the dominant p-type from that point on.  This will
also be when the upper TROF axis will be crossing thru, and so what
is left will probably not be much, but perhaps light snow accums
will be possible Tuesday night and early Wednesday.  This will be
our only realistic chance at a white Christmas, and something to
watch, as a deeper system that digs a bit more south would up the
potential.

(Christmas)

Models have been advertising for several days now a transitional
period this day which should give us a net result of quiet wx with
near seasonal temps.  Nothing has changed with the current model
runs so will let it stand.

TES

&&

.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1155 AM CST Fri Dec 19 2014

Pocket of low level dry air on the IL side of the Mississippi
River continue to make for tricky aviation forecasts. Will
primarily go with MVFR cigs from 1.5-3kft this afternoon, although
its possible that sites along the river (KUIN and STL metro TAFs)
may be on the fringes of this cloud deck. Wedge of dry air is
forecast to hold firm tonight, and while it appears likely that
IFR fog and stratus will once again form over COU in the deeper
low level moisture, trend is less clear cut for sites along the
river. It`s interesting that most guidance isn`t as bullish as
yesterday with IFR development at UIN and STL metro, in spite of
the fact that low level flow does become a bit more southerly
during the predawn hours (albeit weakly so). So, for these
locations have headed towards lower end MVFR cigs/vsbys during the
predawn hours, with the expectation that the primary IFR deck will
remain just west of the MSRVR.

Specifics for KSTL: As mentioned above, area will be on the
western fringes of a pocket of drier low level air over IL. Have
generally gone with bkn MVFR cloud deck through 06z to try to
reflect this, but a slight shift in the edge of this moisture
could mean more or less cloudiness in the MVFR range. Forecast
hints at some lower vsbys and cloudiness during the predawn hours,
but based on the preponderence of guidance have maintained
prevailing ceiling and vsbys in the MVFR range.

Truett

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 191803
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1203 PM CST Fri Dec 19 2014

.UPDATE:
Issued at 1155 AM CST Fri Dec 19 2014

A few tweaks to going forecast...primarily to adjust chaotic cloud
cover over our IL counties and to raise temps there a degree or
two due to a bit more sun. Other change has been to pull mention
of drizzle over mid MO for this afternoon as stratus has
temporarily lifted here. However, did continue mention of flurries
over our se MO counties as very light echoes on n fringes of s
system showing up over nw AR, and heading to the NE.

Truett

&&

.SHORT TERM:  (Through Late This Afternoon)
Issued at 300 AM CST Fri Dec 19 2014

A weak ridge of high pressure which extends from the Great Lakes
region south through the Mid-Mississippi Valley is in control of our
weather today.  Soundings are showing plenty of low level moisture
trapped under an inversion at around 850mb.  The vertical structure
of the atmosphere is much like what we had last weekend with the
moisture stratified in the low levels, so I don`t expect much
sunshine for the majority of the area...with the possible exception
of south central and extreme southwest Illinois.  Some drier air is
trying to drift in on weak easterly low level flow.  Vertical cross
sections show intermittent weak upward motion through the day,
primarily over central Missouri, and short term guidance spits out a
hundredth of QPF here and there.  Additionally, the HRRR shows some
weak simulated radar echos over parts of central and southeast
Missouri today, so have added in a little patchy drizzle to the
forecast.

Carney

.LONG TERM:  (Tonight through Thursday)
Issued at 300 AM CST Fri Dec 19 2014

(Tonight - Saturday)

The brunt of a storm system is expected to pass relatively unnoticed
to our south this evening, and if it weren`t for some interaction
with a more northerly component, would probably result in no
precipitation anywhere, but such as it is, some very light snow
looks to be possible early this evening for an area primarily south
of STL metro.  This arrangement should be short-lived, with much of
the mid and upper level moisture quickly being shunted off to the
east, leaving behind extensive low cloud cover.  At this point,
there is good model consensus on a weak WAA, convergence regime
setting up at the low levels that noses into central MO by midnight
tonight and then snaking its way northward towards the UIN area by
Saturday morning.  Have added in patchy drizzle as a result.  For
now, expecting influence of the surface RIDGE to trump this for STL
metro and areas S and E.  Temps will probably not go very far
tonight with clouds hanging tough, although where the surface RIDGE
is dominant, should see a steady but slow drop...but for areas to
the N and W of STL metro where a light S flow will persist, near
steady temps are expected.  Speaking of temps, especially to the N
and W of STL metro where drizzle is expected to develop, readings
will be within a degree or two of the freezing mark and so this will
probably manifest more as patchy FZDZ for areas in northeast MO and
west-central IL.  Prefer the lower MOS temps for Saturday maxes
given cloud cover expected, but they should still rebound into the
upper 30s and low 40s.

(Sunday - Wednesday)

A rather deep upper level TROF is expected to develop later on
Sunday over the central CONUS and then take a good part of the week
before finally shifting east.  Maintained the highest PoPs for
Monday thru Tuesday, where there is good model consensus on when the
TROF will be close enough, yet its axis still just upstream...and
then reduce to slight chances by Wednesday when the TROF axis by
this time will have shifted to the east.

While much of the precipitation will be just rain, especially on the
front-end, enough cold air starts working in on Tuesday, especially
aloft, that will allow the atmosphere to sustain a changeover to
snow.  The only limiting factor at this point will be surface and/or
boundary layer temps that will ultimately determine the rain vs.
snow question.  GFS and EC MOS surface temps suggest this will not
happen for most locales until late in the day on Tuesday with snow
then expected as the dominant p-type from that point on.  This will
also be when the upper TROF axis will be crossing thru, and so what
is left will probably not be much, but perhaps light snow accums
will be possible Tuesday night and early Wednesday.  This will be
our only realistic chance at a white Christmas, and something to
watch, as a deeper system that digs a bit more south would up the
potential.

(Christmas)

Models have been advertising for several days now a transitional
period this day which should give us a net result of quiet wx with
near seasonal temps.  Nothing has changed with the current model
runs so will let it stand.

TES

&&

.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1155 AM CST Fri Dec 19 2014

Pocket of low level dry air on the IL side of the Mississippi
River continue to make for tricky aviation forecasts. Will
primarily go with MVFR cigs from 1.5-3kft this afternoon, although
its possible that sites along the river (KUIN and STL metro TAFs)
may be on the fringes of this cloud deck. Wedge of dry air is
forecast to hold firm tonight, and while it appears likely that
IFR fog and stratus will once again form over COU in the deeper
low level moisture, trend is less clear cut for sites along the
river. It`s interesting that most guidance isn`t as bullish as
yesterday with IFR development at UIN and STL metro, in spite of
the fact that low level flow does become a bit more southerly
during the predawn hours (albeit weakly so). So, for these
locations have headed towards lower end MVFR cigs/vsbys during the
predawn hours, with the expectation that the primary IFR deck will
remain just west of the MSRVR.

Specifics for KSTL: As mentioned above, area will be on the
western fringes of a pocket of drier low level air over IL. Have
generally gone with bkn MVFR cloud deck through 06z to try to
reflect this, but a slight shift in the edge of this moisture
could mean more or less cloudiness in the MVFR range. Forecast
hints at some lower vsbys and cloudiness during the predawn hours,
but based on the preponderence of guidance have maintained
prevailing ceiling and vsbys in the MVFR range.

Truett

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








000
FXUS63 KLSX 191151
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
551 AM CST Fri Dec 19 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 300 AM CST Fri Dec 19 2014

A weak ridge of high pressure which extends from the Great Lakes
region south through the Mid-Mississippi Valley is in control of our
weather today.  Soundings are showing plenty of low level moisture
trapped under an inversion at around 850mb.  The vertical structure
of the atmosphere is much like what we had last weekend with the
moisture stratified in the low levels, so I don`t expect much
sunshine for the majority of the area...with the possible exception
of south central and extreme southwest Illinois.  Some drier air is
trying to drift in on weak easterly low level flow.  Vertical cross
sections show intermittent weak upward motion through the day,
primarily over central Missouri, and short term guidance spits out a
hundredth of QPF here and there.  Additionally, the HRRR shows some
weak simulated radar echos over parts of central and southeast
Missouri today, so have added in a little patchy drizzle to the
forecast.

Carney

.LONG TERM:  (Tonight through Thursday)
Issued at 300 AM CST Fri Dec 19 2014

(Tonight - Saturday)

The brunt of a storm system is expected to pass relatively unnoticed
to our south this evening, and if it weren`t for some interaction
with a more northerly component, would probably result in no
precipitation anywhere, but such as it is, some very light snow
looks to be possible early this evening for an area primarily south
of STL metro.  This arrangement should be short-lived, with much of
the mid and upper level moisture quickly being shunted off to the
east, leaving behind extensive low cloud cover.  At this point,
there is good model consensus on a weak WAA, convergence regime
setting up at the low levels that noses into central MO by midnight
tonight and then snaking its way northward towards the UIN area by
Saturday morning.  Have added in patchy drizzle as a result.  For
now, expecting influence of the surface RIDGE to trump this for STL
metro and areas S and E.  Temps will probably not go very far
tonight with clouds hanging tough, although where the surface RIDGE
is dominant, should see a steady but slow drop...but for areas to
the N and W of STL metro where a light S flow will persist, near
steady temps are expected.  Speaking of temps, especially to the N
and W of STL metro where drizzle is expected to develop, readings
will be within a degree or two of the freezing mark and so this will
probably manifest more as patchy FZDZ for areas in northeast MO and
west-central IL.  Prefer the lower MOS temps for Saturday maxes
given cloud cover expected, but they should still rebound into the
upper 30s and low 40s.

(Sunday - Wednesday)

A rather deep upper level TROF is expected to develop later on
Sunday over the central CONUS and then take a good part of the week
before finally shifting east.  Maintained the highest PoPs for
Monday thru Tuesday, where there is good model consensus on when the
TROF will be close enough, yet its axis still just upstream...and
then reduce to slight chances by Wednesday when the TROF axis by
this time will have shifted to the east.

While much of the precipitation will be just rain, especially on the
front-end, enough cold air starts working in on Tuesday, especially
aloft, that will allow the atmosphere to sustain a changeover to
snow.  The only limiting factor at this point will be surface and/or
boundary layer temps that will ultimately determine the rain vs.
snow question.  GFS and EC MOS surface temps suggest this will not
happen for most locales until late in the day on Tuesday with snow
then expected as the dominant p-type from that point on.  This will
also be when the upper TROF axis will be crossing thru, and so what
is left will probably not be much, but perhaps light snow accums
will be possible Tuesday night and early Wednesday.  This will be
our only realistic chance at a white Christmas, and something to
watch, as a deeper system that digs a bit more south would up the
potential.

(Christmas)

Models have been advertising for several days now a transitional
period this day which should give us a net result of quiet wx with
near seasonal temps.  Nothing has changed with the current model
runs so will let it stand.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 538 AM CST Fri Dec 19 2014

Expect persistent ceilings across the area today decreasing from
VFR over Illinois to MVFR in eastern Missouri and down to IFR in
central and parts of southeast Missouri. Patchy drizzle is also
possible across the region today, particularly in central
Missouri. Ceilings will likely drop slowly overnight tonight, with
more patchy drizzle over parts of the area.

Specifics for KSTL:

Ceilings will likely stay in MVFR range today. Short-range
guidance is indicating that there will be a period of ceilings
below 2000ft for this morning, and this seems reasonable given
weak low level flow from the northeast and a few obs with ceilings
around 1000ft upstream. Could see a little drizzle in the area
today, but greater chances for drizzle should be over central
Missouri. Expect that MVFR ceilings will continue through tonight.

Carney

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     35  31  41  34 /  10  10  10   5
Quincy          32  29  38  31 /  10  10  10  10
Columbia        35  33  41  34 /  10  10  10   5
Jefferson City  37  34  42  34 /  10  10  10   5
Salem           35  29  41  31 /  10  10   5   0
Farmington      36  30  43  31 /  10  10  10   0

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX







000
FXUS63 KLSX 191151
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
551 AM CST Fri Dec 19 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 300 AM CST Fri Dec 19 2014

A weak ridge of high pressure which extends from the Great Lakes
region south through the Mid-Mississippi Valley is in control of our
weather today.  Soundings are showing plenty of low level moisture
trapped under an inversion at around 850mb.  The vertical structure
of the atmosphere is much like what we had last weekend with the
moisture stratified in the low levels, so I don`t expect much
sunshine for the majority of the area...with the possible exception
of south central and extreme southwest Illinois.  Some drier air is
trying to drift in on weak easterly low level flow.  Vertical cross
sections show intermittent weak upward motion through the day,
primarily over central Missouri, and short term guidance spits out a
hundredth of QPF here and there.  Additionally, the HRRR shows some
weak simulated radar echos over parts of central and southeast
Missouri today, so have added in a little patchy drizzle to the
forecast.

Carney

.LONG TERM:  (Tonight through Thursday)
Issued at 300 AM CST Fri Dec 19 2014

(Tonight - Saturday)

The brunt of a storm system is expected to pass relatively unnoticed
to our south this evening, and if it weren`t for some interaction
with a more northerly component, would probably result in no
precipitation anywhere, but such as it is, some very light snow
looks to be possible early this evening for an area primarily south
of STL metro.  This arrangement should be short-lived, with much of
the mid and upper level moisture quickly being shunted off to the
east, leaving behind extensive low cloud cover.  At this point,
there is good model consensus on a weak WAA, convergence regime
setting up at the low levels that noses into central MO by midnight
tonight and then snaking its way northward towards the UIN area by
Saturday morning.  Have added in patchy drizzle as a result.  For
now, expecting influence of the surface RIDGE to trump this for STL
metro and areas S and E.  Temps will probably not go very far
tonight with clouds hanging tough, although where the surface RIDGE
is dominant, should see a steady but slow drop...but for areas to
the N and W of STL metro where a light S flow will persist, near
steady temps are expected.  Speaking of temps, especially to the N
and W of STL metro where drizzle is expected to develop, readings
will be within a degree or two of the freezing mark and so this will
probably manifest more as patchy FZDZ for areas in northeast MO and
west-central IL.  Prefer the lower MOS temps for Saturday maxes
given cloud cover expected, but they should still rebound into the
upper 30s and low 40s.

(Sunday - Wednesday)

A rather deep upper level TROF is expected to develop later on
Sunday over the central CONUS and then take a good part of the week
before finally shifting east.  Maintained the highest PoPs for
Monday thru Tuesday, where there is good model consensus on when the
TROF will be close enough, yet its axis still just upstream...and
then reduce to slight chances by Wednesday when the TROF axis by
this time will have shifted to the east.

While much of the precipitation will be just rain, especially on the
front-end, enough cold air starts working in on Tuesday, especially
aloft, that will allow the atmosphere to sustain a changeover to
snow.  The only limiting factor at this point will be surface and/or
boundary layer temps that will ultimately determine the rain vs.
snow question.  GFS and EC MOS surface temps suggest this will not
happen for most locales until late in the day on Tuesday with snow
then expected as the dominant p-type from that point on.  This will
also be when the upper TROF axis will be crossing thru, and so what
is left will probably not be much, but perhaps light snow accums
will be possible Tuesday night and early Wednesday.  This will be
our only realistic chance at a white Christmas, and something to
watch, as a deeper system that digs a bit more south would up the
potential.

(Christmas)

Models have been advertising for several days now a transitional
period this day which should give us a net result of quiet wx with
near seasonal temps.  Nothing has changed with the current model
runs so will let it stand.

TES

&&

.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 538 AM CST Fri Dec 19 2014

Expect persistent ceilings across the area today decreasing from
VFR over Illinois to MVFR in eastern Missouri and down to IFR in
central and parts of southeast Missouri. Patchy drizzle is also
possible across the region today, particularly in central
Missouri. Ceilings will likely drop slowly overnight tonight, with
more patchy drizzle over parts of the area.

Specifics for KSTL:

Ceilings will likely stay in MVFR range today. Short-range
guidance is indicating that there will be a period of ceilings
below 2000ft for this morning, and this seems reasonable given
weak low level flow from the northeast and a few obs with ceilings
around 1000ft upstream. Could see a little drizzle in the area
today, but greater chances for drizzle should be over central
Missouri. Expect that MVFR ceilings will continue through tonight.

Carney

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     35  31  41  34 /  10  10  10   5
Quincy          32  29  38  31 /  10  10  10  10
Columbia        35  33  41  34 /  10  10  10   5
Jefferson City  37  34  42  34 /  10  10  10   5
Salem           35  29  41  31 /  10  10   5   0
Farmington      36  30  43  31 /  10  10  10   0

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX








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