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000
FXUS63 KLSX 241536
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
1036 AM CDT Thu Apr 24 2014

.UPDATE:
Issued at 1029 AM CDT Thu Apr 24 2014

Based on latest radar/satellite data...adjusted temperatures
upwards a few degrees across the eastern half of the CWA while
trimming highs over portions of central and northeastern Missouri
where pre-frontal cloudiness and shra with embedded thunder is
moving in late this morning.

For this afternoon...not sure how unstable we will
get...especially for the northern half to two-thirds of the CWFA.
Aforementioned pre-frontal clouds/precipitation could really hamper
instability from rising later on this afternoon. HRRR/RAP really
suffering from warming warm sector way too much as hourly
temperatures even over central Missouri per these near-term models
would climb into the upper 70s and low 80s.
Consequently...developing way too much sfc-based instability. In
addition...stronger shear this afternoon/evening will be over
southeastern Missouri just to south of area so not sure degree of
strong/severe storms this far north. Regardless...very strong
forcing for ascent via strong DCPVA and jet coupling aloft should
produce a widespread shield of rain with embedded thunderstorms
along the front. Will montior situation throughout today and make
additional adjustments/changes to the forecast as necessary.

Gosselin

&&

.SHORT TERM: (Today through Friday
Issued at 329 AM CDT Thu Apr 24 2014

Strong upper level trof is moving east through the Great Plains
this morning. The surface reflection of this trof extends from
eastern Nebraska/Kansas southwest into western Texas. Looks like
good moisture surging ahead of the trof with upper 50s to mid 60s
dewpoints all the way up into eastern Kansas. All short-range
guidance has slowed the eastward progression of this system today,
and thereby also slowing down the precipitation associated with
it. This should allow for a warmer day than previously forecast.
Have bumped up temperatures toward warmer MAV guidance for today.
Should see little but spotty showers across most of the area this
morning, but with increasing chances of precipitation by 18-20Z.
Additional heating of course mean more instability than previously
forecast as well, and the NAM is forecasting a narrow corridor of
1200+ J/Kg MUCAPE ahead of the front this afternoon along and
south of the I-70 corridor. With deep layer shear in excess of 40
kts it does look like some severe storms will be possible.
Convective mode is somewhat indeterminate with shear strong enough
for supercells, but instability probably lacking a bit. I kind of
like the latest run of the HRRR which as a broken line of storms
moving across the area this afternoon, tho with a bit more
instability the convection could easily be more discrete
initially. Front now looks to be into central Missouri by around
00Z, along the Mississippi River by 03-04Z, and through Salem
Illinois by about 06Z. Have adjusted PoPs for this slower
progression through tonight.

Temperatures on Friday are still somewhat in question.  A relatively
mild Pacific airmass will build in behind the front on Friday.
850mb temps don`t really fall off that much and are 10-12C by 00Z
Saturday.  This would suggest mid to upper 70s which makes MOS
numbers a bit too cool across most of the area.  Bumped up a bit
over MOS to compensate.

Carney

.LONG TERM: (Saturday through Wednesday)
Issued at 403 AM CDT Thu Apr 24 2014

Guidance continues to come into better agreement for the weekend.
The secondary front which was forecast to sweep all the way
through Missouri into Arkansas earlier in the week is now only
going to get to southern Iowa according to the model collective.
Still showing a good low level baroclinic zone stretching from
southwest Missouri up into Iowa Saturday through Sunday with a
southwest low level jet ramping up to 40-50kts flowing
perpendicular to the thermal gradient. All models print out some
light precip in response to this on Saturday, primarily over
central and western Missouri but I wouldn`t be surprised to see it
a bit further north/northeast as well if this verifies.
Temperatures will be highly dependent on how much sunshine we end
up getting, but I leaned heavily on the warmer MAV numbers.

Strong warm advection continues ahead of the ginormous trof which
will be moving over the Rockies Saturday night, and it looks like
there could be some nocturnal convection as a a result...mostly
across northern sections of the CWFA.  The trof moves into the Great
Plains on Sunday and closes off while also becoming negatively
tilted.  The resulting wound up, slow moving storm system will draw
abundant moisture into the Mid-Mississippi Valley from the Gulf
producing at least a couple of rounds of showers and thunderstorms
Sunday into Monday night before the associated cold front comes
through and drier air works into the area.  Temperatures should stay
seasonably mild through the Monday with highs near normal.

Tuesday and Wednesday the storm system moves slowly overhead and
then on into the Ohio Valley.  Models print out widespread precip
over the area as cold air aloft moves in with the cut off low.
Heaviest amounts look to be across northern Missouri and southern
Iowa associated with the deformation zone.  While this makes sense
conceptually, still not sure I totally believe the medium range
models as this is a highly anomalous pattern for late April/early.
Stuck relatively close to guidance though as the mass fields on the
GFS and ECMWF are in very good agreement considering strength of
this system and its anomalous nature.

Carney

&&

.AVIATION:  (For the 12z TAFs through 12z Friday Morning)
Issued at 633 AM CDT Thu Apr 24 2014

Needless to say, a complex forecast for this period for area TAF
sites. Showers/thunderstorms currently ongoing over western
Missouri will continue to move ENE this morning, largely fueled by
warm advection and a strong southwesterly low level jet. The HRRR
has maintained a good handle on the evolution of the precipitation
overnight, thus have taken it into consideration regarding future
trends today. Thinking is for SHRA/TSRA from western Missouri to
impact KCOU by around 15Z-16Z and KUIN by 16Z-17Z. This
precipitation should remain northwest of metro TAF sites, thus
have not included precipitation mention for metro sites until late
this afternoon when SHRA/TSRA associated with the cold front are
expected to impact the area. Expect KCOU and KUIN to see a few
rounds of SHRA/TSRA this afternoon, prior to the passage of a cold
front through the terminals by around 00Z (KCOU) and 02Z (KUIN).
For metro TAF sites, expect SHRA/TSRA activity to increase by
ahead of the front, and continue until the front passes between
03Z-04Z, with lingering showers for perhaps another 2 hours
affecting area TAF sites.

Prior to the onset of precipitation, expect continued
gusty southerly/southeasterly winds and VFR flight conditions
along with increasing midlevel clouds. Flight conditions will
decrease to MVFR during SHRA/TSRA, and slowly improve late tonight
post- FROPA. Winds will quickly veer to the west in the wake of
the front, and remain between 10-15KT overnight.

Specifics for KSTL:
VFR flight conditions expected to prevail through the first part
of the forecast period. An area of showers and thunderstorms over
western Missouri continues to move ENE this morning, and is
expected to remain just northwest of the terminal given latest
HRRR guidance. Expect SHRA/TSRA activity to ramp up late this
afternoon ahead of an advancing cold front, and persist until the
front passes through the terminal around 03Z-04Z. Flight
conditions will decrease to MVFR in areas of precipitation, with
ceilings slowly improving overnight after SHRA has ended and
drier air begins to filter into the region in the wake of the cold
front. Winds will remain southerly/southeasterly today, gusting to
20-25KT, and veer quickly to the west behind the front tonight,
remaining between 12-15KT sustained. Clouds are expected to
scatter out by daybreak, providing VFR conditions through the end
of the period on Friday.

JP

&&

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

$$

WFO LSX








000
FXUS63 KLSX 241154
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
654 AM CDT Thu Apr 24 2014

.SHORT TERM: (Today through Friday
Issued at 329 AM CDT Thu Apr 24 2014

Strong upper level trof is moving east through the Great Plains
this morning. The surface reflection of this trof extends from
eastern Nebraska/Kansas southwest into western Texas. Looks like
good moisture surging ahead of the trof with upper 50s to mid 60s
dewpoints all the way up into eastern Kansas. All short-range
guidance has slowed the eastward progression of this system today,
and thereby also slowing down the precipitation associated with
it. This should allow for a warmer day than previously forecast.
Have bumped up temperatures toward warmer MAV guidance for today.
Should see little but spotty showers across most of the area this
morning, but with increasing chances of precipitation by 18-20Z.
Additional heating of course mean more instability than previously
forecast as well, and the NAM is forecasting a narrow corridor of
1200+ J/Kg MUCAPE ahead of the front this afternoon along and
south of the I-70 corridor. With deep layer shear in excess of 40
kts it does look like some severe storms will be possible.
Convective mode is somewhat indeterminate with shear strong enough
for supercells, but instability probably lacking a bit. I kind of
like the latest run of the HRRR which as a broken line of storms
moving across the area this afternoon, tho with a bit more
instability the convection could easily be more discrete
initially. Front now looks to be into central Missouri by around
00Z, along the Mississippi River by 03-04Z, and through Salem
Illinois by about 06Z. Have adjusted PoPs for this slower
progression through tonight.

Temperatures on Friday are still somewhat in question.  A relatively
mild Pacific airmass will build in behind the front on Friday.
850mb temps don`t really fall off that much and are 10-12C by 00Z
Saturday.  This would suggest mid to upper 70s which makes MOS
numbers a bit too cool across most of the area.  Bumped up a bit
over MOS to compensate.

Carney

.LONG TERM: (Saturday through Wednesday)
Issued at 403 AM CDT Thu Apr 24 2014

Guidance continues to come into better agreement for the weekend.
The secondary front which was forecast to sweep all the way
through Missouri into Arkansas earlier in the week is now only
going to get to southern Iowa according to the model collective.
Still showing a good low level baroclinic zone stretching from
southwest Missouri up into Iowa Saturday through Sunday with a
southwest low level jet ramping up to 40-50kts flowing
perpendicular to the thermal gradient. All models print out some
light precip in response to this on Saturday, primarily over
central and western Missouri but I wouldn`t be surprised to see it
a bit further north/northeast as well if this verifies.
Temperatures will be highly dependent on how much sunshine we end
up getting, but I leaned heavily on the warmer MAV numbers.

Strong warm advection continues ahead of the ginormous trof which
will be moving over the Rockies Saturday night, and it looks like
there could be some nocturnal convection as a a result...mostly
across northern sections of the CWFA.  The trof moves into the Great
Plains on Sunday and closes off while also becoming negatively
tilted.  The resulting wound up, slow moving storm system will draw
abundant moisture into the Mid-Mississippi Valley from the Gulf
producing at least a couple of rounds of showers and thunderstorms
Sunday into Monday night before the associated cold front comes
through and drier air works into the area.  Temperatures should stay
seasonably mild through the Monday with highs near normal.

Tuesday and Wednesday the storm system moves slowly overhead and
then on into the Ohio Valley.  Models print out widespread precip
over the area as cold air aloft moves in with the cut off low.
Heaviest amounts look to be across northern Missouri and southern
Iowa associated with the deformation zone.  While this makes sense
conceptually, still not sure I totally believe the medium range
models as this is a highly anomalous pattern for late April/early.
Stuck relatively close to guidance though as the mass fields on the
GFS and ECMWF are in very good agreement considering strength of
this system and its anomalous nature.

Carney

&&

.AVIATION:  (For the 12z TAFs through 12z Friday Morning)
Issued at 633 AM CDT Thu Apr 24 2014

Needless to say, a complex forecast for this period for area TAF
sites. Showers/thunderstorms currently ongoing over western
Missouri will continue to move ENE this morning, largely fueled by
warm advection and a strong southwesterly low level jet. The HRRR
has maintained a good handle on the evolution of the precipitation
overnight, thus have taken it into consideration regarding future
trends today. Thinking is for SHRA/TSRA from western Missouri to
impact KCOU by around 15Z-16Z and KUIN by 16Z-17Z. This
precipitation should remain northwest of metro TAF sites, thus
have not included precipitation mention for metro sites until late
this afternoon when SHRA/TSRA associated with the cold front are
expected to impact the area. Expect KCOU and KUIN to see a few
rounds of SHRA/TSRA this afternoon, prior to the passage of a cold
front through the terminals by around 00Z (KCOU) and 02Z (KUIN).
For metro TAF sites, expect SHRA/TSRA activity to increase by
ahead of the front, and continue until the front passes between
03Z-04Z, with lingering showers for perhaps another 2 hours
affecting area TAF sites.

Prior to the onset of precipitation, expect continued
gusty southerly/southeasterly winds and VFR flight conditions
along with increasing midlevel clouds. Flight conditions will
decrease to MVFR during SHRA/TSRA, and slowly improve late tonight
post- FROPA. Winds will quickly veer to the west in the wake of
the front, and remain between 10-15KT overnight.

Specifics for KSTL:
VFR flight conditions expected to prevail through the first part
of the forecast period. An area of showers and thunderstorms over
western Missouri continues to move ENE this morning, and is
expected to remain just northwest of the terminal given latest
HRRR guidance. Expect SHRA/TSRA activity to ramp up late this
afternoon ahead of an advancing cold front, and persist until the
front passes through the terminal around 03Z-04Z. Flight
conditions will decrease to MVFR in areas of precipitation, with
ceilings slowly improving overnight after SHRA has ended and
drier air begins to filter into the region in the wake of the cold
front. Winds will remain southerly/southeasterly today, gusting to
20-25KT, and veer quickly to the west behind the front tonight,
remaining between 12-15KT sustained. Clouds are expected to
scatter out by daybreak, providing VFR conditions through the end
of the period on Friday.

JP

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     73  50  78  55 /  80  80   0  10
Quincy          68  47  76  51 /  80  80   0  10
Columbia        71  46  78  51 /  80  70   0  10
Jefferson City  72  48  79  50 /  80  80   0  10
Salem           74  49  76  51 /  70  80   0  10
Farmington      75  49  77  49 /  80  80   0  10

&&

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

$$

WFO LSX








000
FXUS63 KLSX 240903
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
403 AM CDT Thu Apr 24 2014

.SHORT TERM: (Today through Friday
Issued at 329 AM CDT Thu Apr 24 2014

Strong upper level trof is moving east through the Great Plains
this morning. The surface reflection of this trof extends from
eastern Nebraska/Kansas southwest into western Texas. Looks like
good moisture surging ahead of the trof with upper 50s to mid 60s
dewpoints all the way up into eastern Kansas. All short-range
guidance has slowed the eastward progression of this system today,
and thereby also slowing down the precipitation associated with
it. This should allow for a warmer day than previously forecast.
Have bumped up temperatures toward warmer MAV guidance for today.
Should see little but spotty showers across most of the area this
morning, but with increasing chances of precipitation by 18-20Z.
Additional heating of course mean more instability than previously
forecast as well, and the NAM is forecasting a narrow corridor of
1200+ J/Kg MUCAPE ahead of the front this afternoon along and
south of the I-70 corridor. With deep layer shear in excess of 40
kts it does look like some severe storms will be possible.
Convective mode is somewhat indeterminate with shear strong enough
for supercells, but instability probably lacking a bit. I kind of
like the latest run of the HRRR which as a broken line of storms
moving across the area this afternoon, tho with a bit more
instability the convection could easily be more discrete
initially. Front now looks to be into central Missouri by around
00Z, along the Mississippi River by 03-04Z, and through Salem
Illinois by about 06Z. Have adjusted PoPs for this slower
progression through tonight.

Temperatures on Friday are still somewhat in question.  A relatively
mild Pacific airmass will build in behind the front on Friday.
850mb temps don`t really fall off that much and are 10-12C by 00Z
Saturday.  This would suggest mid to upper 70s which makes MOS
numbers a bit too cool across most of the area.  Bumped up a bit
over MOS to compensate.

Carney

.LONG TERM: (Saturday through Wednesday)
Issued at 403 AM CDT Thu Apr 24 2014

Guidance continues to come into better agreement for the weekend.
The secondary front which was forecast to sweep all the way
through Missouri into Arkansas earlier in the week is now only
going to get to southern Iowa according to the model collective.
Still showing a good low level baroclinic zone stretching from
southwest Missouri up into Iowa Saturday through Sunday with a
southwest low level jet ramping up to 40-50kts flowing
perpendicular to the thermal gradient. All models print out some
light precip in response to this on Saturday, primarily over
central and western Missouri but I wouldn`t be surprised to see it
a bit further north/northeast as well if this verifies.
Temperatures will be highly dependent on how much sunshine we end
up getting, but I leaned heavily on the warmer MAV numbers.

Strong warm advection continues ahead of the ginormous trof which
will be moving over the Rockies Saturday night, and it looks like
there could be some nocturnal convection as a a result...mostly
across northern sections of the CWFA.  The trof moves into the Great
Plains on Sunday and closes off while also becoming negatively
tilted.  The resulting wound up, slow moving storm system will draw
abundant moisture into the Mid-Mississippi Valley from the Gulf
producing at least a couple of rounds of showers and thunderstorms
Sunday into Monday night before the associated cold front comes
through and drier air works into the area.  Temperatures should stay
seasonably mild through the Monday with highs near normal.

Tuesday and Wednesday the storm system moves slowly overhead and
then on into the Ohio Valley.  Models print out widespread precip
over the area as cold air aloft moves in with the cut off low.
Heaviest amounts look to be across northern Missouri and southern
Iowa associated with the deformation zone.  While this makes sense
conceptually, still not sure I totally believe the medium range
models as this is a highly anomalous pattern for late April/early.
Stuck relatively close to guidance though as the mass fields on the
GFS and ECMWF are in very good agreement considering strength of
this system and its anomalous nature.

Carney

&&

.AVIATION:  (For the 06z TAFs through 06z Thursday Night)
Issued at 1155 PM CDT Wed Apr 23 2014

VFR flight conditions/mid-high clouds will persist overnight with modest
southeast surface winds. A southerly LLJ has developed and is broader
than originally anticipated, and now have marginal LLWS conditions
at all TAF sites. Precipitation timing is still a tough call on
Thursday, but overall the trend and timing is slower than previous
forecasts. Expecting shra and possibly a few rumbles of thunder to
impact KCOU-KUIN in the 16-18z time frame with this activity
weakening as it moves east. Better potential for organized showers
and thunderstorms at all TAFS sites will be on Thursday afternoon/evening
along and ahead of a cold front where I have conditions lowering
to MVFR.

Specifics for KSTL:

VFR flight conditions/mid-high clouds will persist overnight with modest
southeast surface winds. A southerly LLJ has developed and is broader
than originally anticipated, and local radar VWPs suggest marginal LLWS
conditions through 14-15z. Best potential for organized showers
and thunderstorms at KSTL will be between 22-02z on Thursday
afternoon/evening along and ahead of a cold front where I have
conditions lowering to MVFR.

Glass

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     73  50  78  55 /  80  80   0  10
Quincy          68  47  76  51 /  80  80   0  10
Columbia        71  46  78  51 /  80  70   0  10
Jefferson City  72  48  79  50 /  80  80   0  10
Salem           74  49  76  51 /  70  80   0  10
Farmington      75  49  77  49 /  80  80   0  10

&&

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

$$

WFO LSX








000
FXUS63 KLSX 240830
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
330 AM CDT Thu Apr 24 2014

.SHORT TERM: (Today through Friday
Issued at 329 AM CDT Thu Apr 24 2014

Strong upper level trof is moving east through the Great Plains
this morning. The surface reflection of this trof extends from
eastern Nebraska/Kansas southwest into western Texas. Looks like
good moisture surging ahead of the trof with upper 50s to mid 60s
dewpoints all the way up into eastern Kansas. All short-range
guidance has slowed the eastward progression of this system today,
and thereby also slowing down the precipitation associated with
it. This should allow for a warmer day than previously forecast.
Have bumped up temperatures toward warmer MAV guidance for today.
Should see little but spotty showers across most of the area this
morning, but with increasing chances of precipitation by 18-20Z.
Additional heating of course mean more instability than previously
forecast as well, and the NAM is forecasting a narrow corridor of
1200+ J/Kg MUCAPE ahead of the front this afternoon along and
south of the I-70 corridor. With deep layer shear in excess of 40
kts it does look like some severe storms will be possible.
Convective mode is somewhat indeterminate with shear strong enough
for supercells, but instability probably lacking a bit. I kind of
like the latest run of the HRRR which as a broken line of storms
moving across the area this afternoon, tho with a bit more
instability the convection could easily be more discrete
initially. Front now looks to be into central Missouri by around
00Z, along the Mississippi River by 03-04Z, and through Salem
Illinois by about 06Z. Have adjusted PoPs for this slower
progression through tonight.

Temperatures on Friday are still somewhat in question.  A relatively
mild Pacific airmass will build in behind the front on Friday.
850mb temps don`t really fall off that much and are 10-12C by 00Z
Saturday.  This would suggest mid to upper 70s which makes MOS
numbers a bit too cool across most of the area.  Bumped up a bit
over MOS to compensate.

Carney

.LONG TERM:  (Thursday through Next Wednesday)
Issued at 329 PM CDT Wed Apr 23 2014

(Thursday through Saturday)

Main focus for Thurs will be precip chances. Not much change from
the prev forecast other than slowing timing down a bit. Some
questions remain regarding exactly how precip on Thurs will play
out. Believe that the morning hours will be similar to what is
occurring now. Expect precip to intensify during the afternoon and
into the evening along and just ahead of the cdfnt, if enuf heating
can occur. Am becoming more concerned of an isod TSRA becoming
strong to severe, mainly across portions of central MO. However,
this is highly conditional on the amount of heating that can occur
during the day. Will therefore not mention for now and allow the
night shift to reevaluate.

Beyond Thurs, the remainder of the period shud be dry. Did keep low
chance POPs for Sat as a wrmfnt lifts thru the region due to
uncertainty. However, with height rises over the area and better
forcing across KS and wrn MO, believe bulk of precip will remain W
of the CWA.

The focus quickly turns to temps for Fri and Sat. Differences among
mdls leads to a lot of uncertainty for these days. Given the past
couple of warm up events, will trend twd the GFS/local WRF solns.
These solns strong SW to W flow at the sfc with the thermal ridge
pushing into the region. This, coupled with deep mixing, shud allow
temps to reach the 80s for Fri. Sat shud be a little cooler as a
weak cdfnt drops swd across the region, but still a warm day.

(Sunday through Wednesday)

While specifics may differ among mdl solns, general trends are in
fairly good agreement thru the extd period. Mdls suggest an initial
surge of TSRA will push thru the region on Sun thru Mon as a large
low system approaches the area. This system has a threat of severe
weather for much of the CWA. As this system is still 5 plus days
out, time will not be spent discussing details that are likely to
change many times by the end of this weekend.

By Mon night, a S/W associated with the upper low progd to be over
the nrn Atlantic, will approach the upper low over the MO region.
After a brief Fujiwhara interaction, these two low centers are progd
to combine forming one large low system. Mdls differ regarding
placement of this interaction, which will be vital to determining
where precip will occur associated with this low. If the interaction
is further E, the low shud eject precip ewd out of the region, per
the GFS soln. If it is further W, per the ECMWF, precip shud linger
for at least a while.

Regardless, both solns suggest much colder temps will remain locked
in place thru the remainder of next week. Will take a closer look at
temps for Wed and beyond tomorrow, but going forecast of mid 50s may
have too much of an influence on climo and need to be lowered with
future updates.


Tilly

&&

.AVIATION:  (For the 06z TAFs through 06z Thursday Night)
Issued at 1155 PM CDT Wed Apr 23 2014

VFR flight conditions/mid-high clouds will persist overnight with modest
southeast surface winds. A southerly LLJ has developed and is broader
than originally anticipated, and now have marginal LLWS conditions
at all TAF sites. Precipitation timing is still a tough call on
Thursday, but overall the trend and timing is slower than previous
forecasts. Expecting shra and possibly a few rumbles of thunder to
impact KCOU-KUIN in the 16-18z time frame with this activity
weakening as it moves east. Better potential for organized showers
and thunderstorms at all TAFS sites will be on Thursday afternoon/evening
along and ahead of a cold front where I have conditions lowering
to MVFR.

Specifics for KSTL:

VFR flight conditions/mid-high clouds will persist overnight with modest
southeast surface winds. A southerly LLJ has developed and is broader
than originally anticipated, and local radar VWPs suggest marginal LLWS
conditions through 14-15z. Best potential for organized showers
and thunderstorms at KSTL will be between 22-02z on Thursday
afternoon/evening along and ahead of a cold front where I have
conditions lowering to MVFR.

Glass

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     73  50  78  55 /  80  80   0  10
Quincy          68  47  76  51 /  80  80   0  10
Columbia        71  46  78  51 /  80  70   0  10
Jefferson City  72  48  79  50 /  80  80   0  10
Salem           74  49  76  51 /  70  80   0  10
Farmington      75  49  77  49 /  80  80   0  10

&&

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

$$

WFO LSX








000
FXUS63 KLSX 240503
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1203 AM CDT Thu Apr 24 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 236 PM CDT Wed Apr 23 2014

(Tonight)

Mid/upper level ridge axis will pass overhead early tonight with next
system organizing over the south-central Plains. Expect an area of showers
and thunderstorms to organize overnight aided by strong forcing for
large-scale ascent via deepening trough and strong low-level moist/warm
advection. This area of showers and storms should stay west of the area
tonight...but may approach portions of central and northeastern Missouri
by daybreak. Sky cover should increase overnight ahead of aforementioned
system with brisk southeasterly winds continuing throughout the night.
For these reasons...went a few degrees above warmer MAV guidance in most
locations.


Gosselin

.LONG TERM:  (Thursday through Next Wednesday)
Issued at 329 PM CDT Wed Apr 23 2014

(Thursday through Saturday)

Main focus for Thurs will be precip chances. Not much change from
the prev forecast other than slowing timing down a bit. Some
questions remain regarding exactly how precip on Thurs will play
out. Believe that the morning hours will be similar to what is
occurring now. Expect precip to intensify during the afternoon and
into the evening along and just ahead of the cdfnt, if enuf heating
can occur. Am becoming more concerned of an isod TSRA becoming
strong to severe, mainly across portions of central MO. However,
this is highly conditional on the amount of heating that can occur
during the day. Will therefore not mention for now and allow the
night shift to reevaluate.

Beyond Thurs, the remainder of the period shud be dry. Did keep low
chance POPs for Sat as a wrmfnt lifts thru the region due to
uncertainty. However, with height rises over the area and better
forcing across KS and wrn MO, believe bulk of precip will remain W
of the CWA.

The focus quickly turns to temps for Fri and Sat. Differences among
mdls leads to a lot of uncertainty for these days. Given the past
couple of warm up events, will trend twd the GFS/local WRF solns.
These solns strong SW to W flow at the sfc with the thermal ridge
pushing into the region. This, coupled with deep mixing, shud allow
temps to reach the 80s for Fri. Sat shud be a little cooler as a
weak cdfnt drops swd across the region, but still a warm day.

(Sunday through Wednesday)

While specifics may differ among mdl solns, general trends are in
fairly good agreement thru the extd period. Mdls suggest an initial
surge of TSRA will push thru the region on Sun thru Mon as a large
low system approaches the area. This system has a threat of severe
weather for much of the CWA. As this system is still 5 plus days
out, time will not be spent discussing details that are likely to
change many times by the end of this weekend.

By Mon night, a S/W associated with the upper low progd to be over
the nrn Atlantic, will approach the upper low over the MO region.
After a brief Fujiwhara interaction, these two low centers are progd
to combine forming one large low system. Mdls differ regarding
placement of this interaction, which will be vital to determining
where precip will occur associated with this low. If the interaction
is further E, the low shud eject precip ewd out of the region, per
the GFS soln. If it is further W, per the ECMWF, precip shud linger
for at least a while.

Regardless, both solns suggest much colder temps will remain locked
in place thru the remainder of next week. Will take a closer look at
temps for Wed and beyond tomorrow, but going forecast of mid 50s may
have too much of an influence on climo and need to be lowered with
future updates.


Tilly

&&

.AVIATION:  (For the 06z TAFs through 06z Thursday Night)
Issued at 1155 PM CDT Wed Apr 23 2014

VFR flight conditions/mid-high clouds will persist overnight with modest
southeast surface winds. A southerly LLJ has developed and is broader
than originally anticipated, and now have marginal LLWS conditions
at all TAF sites. Precipitation timing is still a tough call on
Thursday, but overall the trend and timing is slower than previous
forecasts. Expecting shra and possibly a few rumbles of thunder to
impact KCOU-KUIN in the 16-18z time frame with this activity
weakening as it moves east. Better potential for organized showers
and thunderstorms at all TAFS sites will be on Thursday afternoon/evening
along and ahead of a cold front where I have conditions lowering
to MVFR.

Specifics for KSTL:

VFR flight conditions/mid-high clouds will persist overnight with modest
southeast surface winds. A southerly LLJ has developed and is broader
than originally anticipated, and local radar VWPs suggest marginal LLWS
conditions through 14-15z. Best potential for organized showers
and thunderstorms at KSTL will be between 22-02z on Thursday
afternoon/evening along and ahead of a cold front where I have
conditions lowering to MVFR.

Glass

&&

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

$$

WFO LSX








000
FXUS63 KLSX 232317
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
617 PM CDT Wed Apr 23 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 236 PM CDT Wed Apr 23 2014

(Tonight)

Mid/upper level ridge axis will pass overhead early tonight with next
system organizing over the south-central Plains. Expect an area of showers
and thunderstorms to organize overnight aided by strong forcing for
large-scale ascent via deepening trough and strong low-level moist/warm
advection. This area of showers and storms should stay west of the area
tonight...but may approach portions of central and northeastern Missouri
by daybreak. Sky cover should increase overnight ahead of aforementioned
system with brisk southeasterly winds continuing throughout the night.
For these reasons...went a few degrees above warmer MAV guidance in most
locations.


Gosselin

.LONG TERM:  (Thursday through Next Wednesday)
Issued at 329 PM CDT Wed Apr 23 2014

(Thursday through Saturday)

Main focus for Thurs will be precip chances. Not much change from
the prev forecast other than slowing timing down a bit. Some
questions remain regarding exactly how precip on Thurs will play
out. Believe that the morning hours will be similar to what is
occurring now. Expect precip to intensify during the afternoon and
into the evening along and just ahead of the cdfnt, if enuf heating
can occur. Am becoming more concerned of an isod TSRA becoming
strong to severe, mainly across portions of central MO. However,
this is highly conditional on the amount of heating that can occur
during the day. Will therefore not mention for now and allow the
night shift to reevaluate.

Beyond Thurs, the remainder of the period shud be dry. Did keep low
chance POPs for Sat as a wrmfnt lifts thru the region due to
uncertainty. However, with height rises over the area and better
forcing across KS and wrn MO, believe bulk of precip will remain W
of the CWA.

The focus quickly turns to temps for Fri and Sat. Differences among
mdls leads to a lot of uncertainty for these days. Given the past
couple of warm up events, will trend twd the GFS/local WRF solns.
These solns strong SW to W flow at the sfc with the thermal ridge
pushing into the region. This, coupled with deep mixing, shud allow
temps to reach the 80s for Fri. Sat shud be a little cooler as a
weak cdfnt drops swd across the region, but still a warm day.

(Sunday through Wednesday)

While specifics may differ among mdl solns, general trends are in
fairly good agreement thru the extd period. Mdls suggest an initial
surge of TSRA will push thru the region on Sun thru Mon as a large
low system approaches the area. This system has a threat of severe
weather for much of the CWA. As this system is still 5 plus days
out, time will not be spent discussing details that are likely to
change many times by the end of this weekend.

By Mon night, a S/W associated with the upper low progd to be over
the nrn Atlantic, will approach the upper low over the MO region.
After a brief Fujiwhara interaction, these two low centers are progd
to combine forming one large low system. Mdls differ regarding
placement of this interaction, which will be vital to determining
where precip will occur associated with this low. If the interaction
is further E, the low shud eject precip ewd out of the region, per
the GFS soln. If it is further W, per the ECMWF, precip shud linger
for at least a while.

Regardless, both solns suggest much colder temps will remain locked
in place thru the remainder of next week. Will take a closer look at
temps for Wed and beyond tomorrow, but going forecast of mid 50s may
have too much of an influence on climo and need to be lowered with
future updates.


Tilly

&&

.AVIATION:  (For the 00z TAFs through 00z Thursday Evening)
Issued at 607 PM CDT Wed Apr 23 2014

Expecting VFR flight conditions/mid-high clouds tonight with
modest southeast winds. A southerly LLJ will develop later this
evening bringing marginal LLWS conditions to KUIN and KCOU
overnight. Precipitation trends are a tough call on Thursday.
Continued the forecast from the earlier TAFS bringing predominately
shra and marginal thunder potential into KUIN/KCOU in the 14-15z
time frame and after 18z in the St. Louis area. This will be
residual showers/tsra which develops across the Plains tonight and
pushes east and the remaining coverage is always hard to gage.
Seems like a better potential for showers and thunderstorms at all
TAFS sites will be on Thursday afternoon along/ahead of a cold
front where I have conditions lowering to MVFR.

Specifics for KSTL:

Expecting VFR flight conditions/mid-high clouds tonight with modest
southeast winds. Precipitation trends are a tough call on Thursday.
Continued the forecast from the earlier TAFS bringing predominately
shra after 18z. This will be residual showers which develops
across the Plains tonight and pushes east and the remaining
coverage is always hard to gage. Seems like a better potential for
showers and thunderstorms will be late Thursday afternoon and
early evening along/ahead of a cold front where I have conditions
lowering to MVFR.

Glass

&&

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

$$

WFO LSX








000
FXUS63 KLSX 232031
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
331 PM CDT Wed Apr 23 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 236 PM CDT Wed Apr 23 2014

(Tonight)

Mid/upper level ridge axis will pass overhead early tonight with next
system organizing over the south-central Plains. Expect an area of showers
and thunderstorms to organize overnight aided by strong forcing for
large-scale ascent via deepening trough and strong low-level moist/warm
advection. This area of showers and storms should stay west of the area
tonight...but may approach portions of central and northeastern Missouri
by daybreak. Sky cover should increase overnight ahead of aforementioned
system with brisk southeasterly winds continuing throughout the night.
For these reasons...went a few degrees above warmer MAV guidance in most
locations.


Gosselin

.LONG TERM:  (Thursday through Next Wednesday)
Issued at 329 PM CDT Wed Apr 23 2014

(Thursday through Saturday)

Main focus for Thurs will be precip chances. Not much change from
the prev forecast other than slowing timing down a bit. Some
questions remain regarding exactly how precip on Thurs will play
out. Believe that the morning hours will be similar to what is
occurring now. Expect precip to intensify during the afternoon and
into the evening along and just ahead of the cdfnt, if enuf heating
can occur. Am becoming more concerned of an isod TSRA becoming
strong to severe, mainly across portions of central MO. However,
this is highly conditional on the amount of heating that can occur
during the day. Will therefore not mention for now and allow the
night shift to reevaluate.

Beyond Thurs, the remainder of the period shud be dry. Did keep low
chance POPs for Sat as a wrmfnt lifts thru the region due to
uncertainty. However, with height rises over the area and better
forcing across KS and wrn MO, believe bulk of precip will remain W
of the CWA.

The focus quickly turns to temps for Fri and Sat. Differences among
mdls leads to a lot of uncertainty for these days. Given the past
couple of warm up events, will trend twd the GFS/local WRF solns.
These solns strong SW to W flow at the sfc with the thermal ridge
pushing into the region. This, coupled with deep mixing, shud allow
temps to reach the 80s for Fri. Sat shud be a little cooler as a
weak cdfnt drops swd across the region, but still a warm day.

(Sunday through Wednesday)

While specifics may differ among mdl solns, general trends are in
fairly good agreement thru the extd period. Mdls suggest an initial
surge of TSRA will push thru the region on Sun thru Mon as a large
low system approaches the area. This system has a threat of severe
weather for much of the CWA. As this system is still 5 plus days
out, time will not be spent discussing details that are likely to
change many times by the end of this weekend.

By Mon night, a S/W associated with the upper low progd to be over
the nrn Atlantic, will approach the upper low over the MO region.
After a brief Fujiwhara interaction, these two low centers are progd
to combine forming one large low system. Mdls differ regarding
placement of this interaction, which will be vital to determining
where precip will occur associated with this low. If the interaction
is further E, the low shud eject precip ewd out of the region, per
the GFS soln. If it is further W, per the ECMWF, precip shud linger
for at least a while.

Regardless, both solns suggest much colder temps will remain locked
in place thru the remainder of next week. Will take a closer look at
temps for Wed and beyond tomorrow, but going forecast of mid 50s may
have too much of an influence on climo and need to be lowered with
future updates.


Tilly

&&

.AVIATION:  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1223 PM CDT Wed Apr 23 2014

Area of showers currently over western Missouri is expected to weaken
this afternoon and is not expected to affect KCOU or KUIN at this
time. Main impact will be increasing midlevel cloudiness at
terminals. Southeast winds are expected to prevail through the
night ahead of next system which will move eastward. Southerly
low-level jet of 40-45 knots near 2000 feet AGL over central
Missouri and west- central Illinois could produce low- level wind
shear and added mention for KCOU and KUIN. For tomorrow...another
area of showers with embedded thunderstorms is expected to move
into the area from west to east ahead of a cold front from late
morning into the early afternoon. Actual frontal passage and
accompanied wind shift is likely to be after this valid forecast
period.


Specifics for KSTL:

Increasing midlevel cloudiness is expected through the afternoon at
the terminal. Southeast winds are expected to prevail through the night
ahead of next system which will move eastward. Low-level jet axis
should stay to the west of KSTL precluding mention of LLWS. For
tomorrow...another area of showers with embedded thunderstorms is
expected to affect Lambert Field around midday. However...actual
frontal passage and accompanied wind shift is likely to be just after
this valid forecast period.

Gosselin

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     52  73  45  81 /  10  80  40   0
Quincy          50  66  43  79 /  20  80  20   0
Columbia        54  71  44  80 /  60  80  10   0
Jefferson City  54  71  44  80 /  50  80  10   0
Salem           48  74  46  78 /   5  70  80   0
Farmington      47  75  46  78 /  10  80  40   0

&&

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

$$

WFO LSX








000
FXUS63 KLSX 231936
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
236 PM CDT Wed Apr 23 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 236 PM CDT Wed Apr 23 2014

(Tonight)

Mid/upper level ridge axis will pass overhead early tonight with next
system organizing over the south-central Plains. Expect an area of showers
and thunderstorms to organize overnight aided by strong forcing for
large-scale ascent via deepening trough and strong low-level moist/warm
advection. This area of showers and storms should stay west of the area
tonight...but may approach portions of central and northeastern Missouri
by daybreak. Sky cover should increase overnight ahead of aforementioned
system with brisk southeasterly winds continuing throughout the night.
For these reasons...went a few degrees above warmer MAV guidance in most
locations.


Gosselin


.LONG TERM:  (Saturday through Tuesday)
Issued at 342 AM CDT Wed Apr 23 2014

While the medium range guidance is coming into better agreement on
the overall synoptic pattern, the smaller scale is still unclear.
Generally, a secondary cold front will dip south across the Upper
Midwest driven south by the last vestiges of Thursday`s shortwave.
The front will stall somewhere across the Midwest on Saturday,
though models can`t make up their minds where.  GFS stalls the front
across south/southwest Missouri Saturday morning, while the ECMWF
stalls it out over northern Iowa.  The GEM is right about in the
middle stalling the front over northern Missouri.  All three models
have some low level baroclinicity over our area, whether it is the
primary baroclinic zone associated with the front (GFS/GEM) or a
secondary baroclinic zone left over from the Pacific airmass which
will be exiting to the east (EC).  Warm advection begins Saturday
morning with a 30+ kt low level jet pointed at this baroclinic zone
and all three models print out some light precip.  Have therefore
kept chance pops going in central Missouri, and would not be
surprised if subsequent shifts need to bump up pops a bit more
across the area if model trends become more consistent.

The front remains stalled somewhere between Springfield Missouri and
Davenport Iowa depending on which model you believe through Monday
as the longwave trof over the Pacific moves inland, and becomes
negatively tilted over the Rockies and Great Plains.  A strong
surface low develops as a result and it moves into the Mississippi
Valley Monday night into Tuesday.  The upper trof cuts off and
becomes stagnant while the surface low tracks across Missouri into
the Ohio Valley Tuesday.  Pattern is more reminiscent of late Fall
or Winter than mid to late Spring.  Unsure how likely this is to
happen, but this is at least the second run in a row that I`ve seen
do this.  Will have to wait and see, but right now it looks like a
cold/wet end to April.

Carney

&&

.AVIATION:  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1223 PM CDT Wed Apr 23 2014

Area of showers currently over western Missouri is expected to weaken
this afternoon and is not expected to affect KCOU or KUIN at this
time. Main impact will be increasing midlevel cloudiness at
terminals. Southeast winds are expected to prevail through the
night ahead of next system which will move eastward. Southerly
low-level jet of 40-45 knots near 2000 feet AGL over central
Missouri and west- central Illinois could produce low- level wind
shear and added mention for KCOU and KUIN. For tomorrow...another
area of showers with embedded thunderstorms is expected to move
into the area from west to east ahead of a cold front from late
morning into the early afternoon. Actual frontal passage and
accompanied wind shift is likely to be after this valid forecast
period.


Specifics for KSTL:

Increasing midlevel cloudiness is expected through the afternoon at
the terminal. Southeast winds are expected to prevail through the night
ahead of next system which will move eastward. Low-level jet axis
should stay to the west of KSTL precluding mention of LLWS. For
tomorrow...another area of showers with embedded thunderstorms is
expected to affect Lambert Field around midday. However...actual
frontal passage and accompanied wind shift is likely to be just after
this valid forecast period.

Gosselin

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     52  73  45  81 /  10  80  40   0
Quincy          50  66  43  79 /  20  80  20   0
Columbia        54  71  44  80 /  60  80  10   0
Jefferson City  54  71  44  80 /  50  80  10   0
Salem           48  74  46  78 /   5  70  80   0
Farmington      47  75  46  78 /  10  80  40   0

&&

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

$$

WFO LSX








000
FXUS63 KLSX 231734
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1234 PM CDT Wed Apr 23 2014

.SHORT TERM: (Today through Friday)
Issued at 342 AM CDT Wed Apr 23 2014

Surface ridge extending from Wisconsin south/southwest into the
Mid-Mississippi Valley and back into east Texas will move east today
ahead of developing low pressure over the Great Plains.  Increasing
southerly low level flow will result.  All short-range model
guidance develops an area of warm advection showers over the eastern
Plains and pushes it east northeast into northwest Missouri and Iowa
today.  Looks possible that the southeast edge of the showers could
clip our area, but low level air is pretty dry according to the NAM,
GFS, and RUC and the primary thrust of moisture return will be back
over western Missouri so have only introduced slight chance PoPs
over our northwest counties.  We should see highs pretty close to
what occurred yesterday even with the warm advection since we`ll be
starting out the day cooler than Tuesday morning.  The exception
will be central Missouri where morning lows should be a bit warmer
than areas further east.

The shortwave currently digging across the Rockies will move out
into the Great Plains tonight and the resulting cold front will move
into northwest Missouri around 12Z.  Still looks like showers and
thunderstorms will be ongoing along and ahead of the front as it
moves through the CWFA on Thursday.  Diurnal heating will likely be
limited due to cloud cover and advancing precip from the west, so
instability still looks relatively weak.  While there should be
enough CAPE for thunderstorms, widespread severe weather does not
look likely at this time.  Stuck closer to the warmer MAV guidance
for highs since morning lows will be around 50 across the area and
15-20 degrees of rise should be attainable in warm advection this
time of year regardless of cloud cover.

Guidance is in good agreement with pushing the front through the
entire area shortly after 00Z.  Still have some lingering precip
east of the Mississippi River Thursday evening as the front exits,
but dry after midnight.  Pacific high builds across the region
Friday morning.  As opposed to a colder Canadian airmass, the
Pacific ridge should produce temperatures near or slightly above
normal in the upper 40s to low 50s Friday morning.  West-southwest
flow develops Friday morning as the high scoots quickly into the
Tennessee Valley so expect temperatures to rebound into the mid and
upper 70s.

Carney

.LONG TERM:  (Saturday through Tuesday)
Issued at 342 AM CDT Wed Apr 23 2014

While the medium range guidance is coming into better agreement on
the overall synoptic pattern, the smaller scale is still unclear.
Generally, a secondary cold front will dip south across the Upper
Midwest driven south by the last vestiges of Thursday`s shortwave.
The front will stall somewhere across the Midwest on Saturday,
though models can`t make up their minds where.  GFS stalls the front
across south/southwest Missouri Saturday morning, while the ECMWF
stalls it out over northern Iowa.  The GEM is right about in the
middle stalling the front over northern Missouri.  All three models
have some low level baroclinicity over our area, whether it is the
primary baroclinic zone associated with the front (GFS/GEM) or a
secondary baroclinic zone left over from the Pacific airmass which
will be exiting to the east (EC).  Warm advection begins Saturday
morning with a 30+ kt low level jet pointed at this baroclinic zone
and all three models print out some light precip.  Have therefore
kept chance pops going in central Missouri, and would not be
surprised if subsequent shifts need to bump up pops a bit more
across the area if model trends become more consistent.

The front remains stalled somewhere between Springfield Missouri and
Davenport Iowa depending on which model you believe through Monday
as the longwave trof over the Pacific moves inland, and becomes
negatively tilted over the Rockies and Great Plains.  A strong
surface low develops as a result and it moves into the Mississippi
Valley Monday night into Tuesday.  The upper trof cuts off and
becomes stagnant while the surface low tracks across Missouri into
the Ohio Valley Tuesday.  Pattern is more reminiscent of late Fall
or Winter than mid to late Spring.  Unsure how likely this is to
happen, but this is at least the second run in a row that I`ve seen
do this.  Will have to wait and see, but right now it looks like a
cold/wet end to April.

Carney

&&

.AVIATION:  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1223 PM CDT Wed Apr 23 2014

Area of showers currently over western Missouri is expected to weaken
this afternoon and is not expected to affect KCOU or KUIN at this
time. Main impact will be increasing midlevel cloudiness at
terminals. Southeast winds are expected to prevail through the
night ahead of next system which will move eastward. Southerly
low-level jet of 40-45 knots near 2000 feet AGL over central
Missouri and west- central Illinois could produce low- level wind
shear and added mention for KCOU and KUIN. For tomorrow...another
area of showers with embedded thunderstorms is expected to move
into the area from west to east ahead of a cold front from late
morning into the early afternoon. Actual frontal passage and
accompanied wind shift is likely to be after this valid forecast
period.


Specifics for KSTL:

Increasing midlevel cloudiness is expected through the afternoon at
the terminal. Southeast winds are expected to prevail through the night
ahead of next system which will move eastward. Low-level jet axis
should stay to the west of KSTL precluding mention of LLWS. For
tomorrow...another area of showers with embedded thunderstorms is
expected to affect Lambert Field around midday. However...actual
frontal passage and accompanied wind shift is likely to be just after
this valid forecast period.

Gosselin

&&

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

$$

WFO LSX








000
FXUS63 KLSX 231143
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
643 AM CDT Wed Apr 23 2014

.SHORT TERM: (Today through Friday)
Issued at 342 AM CDT Wed Apr 23 2014

Surface ridge extending from Wisconsin south/southwest into the
Mid-Mississippi Valley and back into east Texas will move east today
ahead of developing low pressure over the Great Plains.  Increasing
southerly low level flow will result.  All short-range model
guidance develops an area of warm advection showers over the eastern
Plains and pushes it east northeast into northwest Missouri and Iowa
today.  Looks possible that the southeast edge of the showers could
clip our area, but low level air is pretty dry according to the NAM,
GFS, and RUC and the primary thrust of moisture return will be back
over western Missouri so have only introduced slight chance PoPs
over our northwest counties.  We should see highs pretty close to
what occurred yesterday even with the warm advection since we`ll be
starting out the day cooler than Tuesday morning.  The exception
will be central Missouri where morning lows should be a bit warmer
than areas further east.

The shortwave currently digging across the Rockies will move out
into the Great Plains tonight and the resulting cold front will move
into northwest Missouri around 12Z.  Still looks like showers and
thunderstorms will be ongoing along and ahead of the front as it
moves through the CWFA on Thursday.  Diurnal heating will likely be
limited due to cloud cover and advancing precip from the west, so
instability still looks relatively weak.  While there should be
enough CAPE for thunderstorms, widespread severe weather does not
look likely at this time.  Stuck closer to the warmer MAV guidance
for highs since morning lows will be around 50 across the area and
15-20 degrees of rise should be attainable in warm advection this
time of year regardless of cloud cover.

Guidance is in good agreement with pushing the front through the
entire area shortly after 00Z.  Still have some lingering precip
east of the Mississippi River Thursday evening as the front exits,
but dry after midnight.  Pacific high builds across the region
Friday morning.  As opposed to a colder Canadian airmass, the
Pacific ridge should produce temperatures near or slightly above
normal in the upper 40s to low 50s Friday morning.  West-southwest
flow develops Friday morning as the high scoots quickly into the
Tennessee Valley so expect temperatures to rebound into the mid and
upper 70s.

Carney

.LONG TERM:  (Saturday through Tuesday)
Issued at 342 AM CDT Wed Apr 23 2014

While the medium range guidance is coming into better agreement on
the overall synoptic pattern, the smaller scale is still unclear.
Generally, a secondary cold front will dip south across the Upper
Midwest driven south by the last vestiges of Thursday`s shortwave.
The front will stall somewhere across the Midwest on Saturday,
though models can`t make up their minds where.  GFS stalls the front
across south/southwest Missouri Saturday morning, while the ECMWF
stalls it out over northern Iowa.  The GEM is right about in the
middle stalling the front over northern Missouri.  All three models
have some low level baroclinicity over our area, whether it is the
primary baroclinic zone associated with the front (GFS/GEM) or a
secondary baroclinic zone left over from the Pacific airmass which
will be exiting to the east (EC).  Warm advection begins Saturday
morning with a 30+ kt low level jet pointed at this baroclinic zone
and all three models print out some light precip.  Have therefore
kept chance pops going in central Missouri, and would not be
surprised if subsequent shifts need to bump up pops a bit more
across the area if model trends become more consistent.

The front remains stalled somewhere between Springfield Missouri and
Davenport Iowa depending on which model you believe through Monday
as the longwave trof over the Pacific moves inland, and becomes
negatively tilted over the Rockies and Great Plains.  A strong
surface low develops as a result and it moves into the Mississippi
Valley Monday night into Tuesday.  The upper trof cuts off and
becomes stagnant while the surface low tracks across Missouri into
the Ohio Valley Tuesday.  Pattern is more reminiscent of late Fall
or Winter than mid to late Spring.  Unsure how likely this is to
happen, but this is at least the second run in a row that I`ve seen
do this.  Will have to wait and see, but right now it looks like a
cold/wet end to April.

Carney

&&

.AVIATION:  (For the 12z TAFs through 12z Thursday Morning)
Issued at 628 AM CDT Wed Apr 23 2014

VFR flight conditions will continue to prevail this forecast
period, with winds veering and becoming more southerly as the
surface ridge moves off to the east. The next system which will
impact the area is taking shape over the plains, and as it moves
east, area TAF sites will see winds increase to roughly 10-15KT by
late morning/early afternoon in response to a tightening pressure
gradient and increased southerly flow. The aforementioned pressure
gradient should also be enough to produce some gusts around
20-22KT beginning by late afternoon, mainly impacting KCOU and
KUIN. Only increasing midlevel clouds are expected through the
period, and while there is a chance for precipitation to move into
central and northeast Missouri late Wednesday night, exact timing
has yet to be pinned down, and as the onset would be in the last
few hours of the forecast period, have not included mention at
this time.

Specifics for KSTL:
VFR flight conditions will prevail through the forecast period,
with winds continuing to veer and become more southerly as the
surface ridge moves east and the next system to impact the area
takes shape over the plains. Expect winds to increase to about
12-14KT by early afternoon, remaining fairly steady overnight, and
become gusty Thursday morning as the surface pressure gradient
tightens ahead of the approaching system. Showers and
thunderstorms will move through the area on Thursday, though exact
timing for impact at KSTL has yet to be pinned down, and as it
would likely be within the last couple hours of the forecast
period, have not mentioned it in the TAF at this time. Prior to
the storms, expect a gradual increase in midlevel clouds
overspreading the area from west to east today/tonight.

JP

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     69  52  72  52 /   5  10  80  30
Quincy          66  49  66  46 /  10  20  80  20
Columbia        72  53  70  47 /  10  30  80  10
Jefferson City  75  53  70  47 /  10  20  80  10
Salem           65  49  72  49 /   5   5  70  50
Farmington      69  48  73  47 /   5   5  80  30

&&

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

$$

WFO LSX








000
FXUS63 KLSX 230844
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
344 AM CDT Wed Apr 23 2014

.SHORT TERM: (Today through Friday)
Issued at 342 AM CDT Wed Apr 23 2014

Surface ridge extending from Wisconsin south/southwest into the
Mid-Mississippi Valley and back into east Texas will move east today
ahead of developing low pressure over the Great Plains.  Increasing
southerly low level flow will result.  All short-range model
guidance develops an area of warm advection showers over the eastern
Plains and pushes it east northeast into northwest Missouri and Iowa
today.  Looks possible that the southeast edge of the showers could
clip our area, but low level air is pretty dry according to the NAM,
GFS, and RUC and the primary thrust of moisture return will be back
over western Missouri so have only introduced slight chance PoPs
over our northwest counties.  We should see highs pretty close to
what occurred yesterday even with the warm advection since we`ll be
starting out the day cooler than Tuesday morning.  The exception
will be central Missouri where morning lows should be a bit warmer
than areas further east.

The shortwave currently digging across the Rockies will move out
into the Great Plains tonight and the resulting cold front will move
into northwest Missouri around 12Z.  Still looks like showers and
thunderstorms will be ongoing along and ahead of the front as it
moves through the CWFA on Thursday.  Diurnal heating will likely be
limited due to cloud cover and advancing precip from the west, so
instability still looks relatively weak.  While there should be
enough CAPE for thunderstorms, widespread severe weather does not
look likely at this time.  Stuck closer to the warmer MAV guidance
for highs since morning lows will be around 50 across the area and
15-20 degrees of rise should be attainable in warm advection this
time of year regardless of cloud cover.

Guidance is in good agreement with pushing the front through the
entire area shortly after 00Z.  Still have some lingering precip
east of the Mississippi River Thursday evening as the front exits,
but dry after midnight.  Pacific high builds across the region
Friday morning.  As opposed to a colder Canadian airmass, the
Pacific ridge should produce temperatures near or slightly above
normal in the upper 40s to low 50s Friday morning.  West-southwest
flow develops Friday morning as the high scoots quickly into the
Tennessee Valley so expect temperatures to rebound into the mid and
upper 70s.

Carney

.LONG TERM:  (Saturday through Tuesday)
Issued at 342 AM CDT Wed Apr 23 2014

While the medium range guidance is coming into better agreement on
the overall synoptic pattern, the smaller scale is still unclear.
Generally, a secondary cold front will dip south across the Upper
Midwest driven south by the last vestiges of Thursday`s shortwave.
The front will stall somewhere across the Midwest on Saturday,
though models can`t make up their minds where.  GFS stalls the front
across south/southwest Missouri Saturday morning, while the ECMWF
stalls it out over northern Iowa.  The GEM is right about in the
middle stalling the front over northern Missouri.  All three models
have some low level baroclinicity over our area, whether it is the
primary baroclinic zone associated with the front (GFS/GEM) or a
secondary baroclinic zone left over from the Pacific airmass which
will be exiting to the east (EC).  Warm advection begins Saturday
morning with a 30+ kt low level jet pointed at this baroclinic zone
and all three models print out some light precip.  Have therefore
kept chance pops going in central Missouri, and would not be
surprised if subsequent shifts need to bump up pops a bit more
across the area if model trends become more consistent.

The front remains stalled somewhere between Springfield Missouri and
Davenport Iowa depending on which model you believe through Monday
as the longwave trof over the Pacific moves inland, and becomes
negatively tilted over the Rockies and Great Plains.  A strong
surface low develops as a result and it moves into the Mississippi
Valley Monday night into Tuesday.  The upper trof cuts off and
becomes stagnant while the surface low tracks across Missouri into
the Ohio Valley Tuesday.  Pattern is more reminiscent of late Fall
or Winter than mid to late Spring.  Unsure how likely this is to
happen, but this is at least the second run in a row that I`ve seen
do this.  Will have to wait and see, but right now it looks like a
cold/wet end to April.

Carney

&&

.AVIATION:  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1126 PM CDT Tue Apr 22 2014

VFR flight conditions expected through the forecast period with
clear skies or scattered mid-hi clouds overnight and mid-high
clouds on Wednesday. Light winds tonight will become southeasterly
and increase on Wednesday morning.

Specifics for KSTL:

VFR flight conditions expected through the forecast period with
clear skies or scattered mid-hi clouds overnight and mid-high
clouds on Wednesday. Light winds tonight will become southeasterly
and increase on Wednesday morning.

Glass

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     69  52  72  52 /   5  10  80  30
Quincy          66  49  66  46 /  10  20  80  20
Columbia        72  53  70  47 /  10  30  80  10
Jefferson City  75  53  70  47 /  10  20  80  10
Salem           65  49  72  49 /   5   5  70  50
Farmington      69  48  73  47 /   5   5  80  30

&&

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

$$

WFO LSX








000
FXUS63 KLSX 230429
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1129 PM CDT Tue Apr 22 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 259 PM CDT Tue Apr 22 2014

Surface ridge to move off to the east tonight allowing southerly
winds to return to the region by Wednesday. In the meantime, clear
skies and light north winds to prevail tonight. Lows will drop into
the low to mid 40s.

Byrd

.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 259 PM CDT Tue Apr 22 2014

On Wednesday, mid and high clouds will be on the increase as next
weather system approaches region. With southeast to south winds
temperatures to warm up into the mid 60s to mid 70s.

As for precipitation chances, feel that there is a lot of dry air to
overcome, so best chances for showers and thunderstorms will be on
Thursday as cold front swings through region. Not a lot of
instability with this system with highest capes, around 500 j/kg,
especially along and south of I-70. Activity to exit area Thursday
evening. Highs on Thursday will depend on cloud cover, precipitation
and timing of cold front. For now have mid 60s to low 70s.

Not a lot of caa behind this system and will see a secondary frontal
boundary slide south through region on Friday stalling out well
south of forecast area. Do not anticipate any precipitation with
this boundary, but will become the focus of activity later in the
weekend and into early next week for our area. Highs on Friday will
be in the 70s.

Extended models still have timing and placement issues with
activity. For now have showers and thunderstorms developing across
western portions of forecast area on Saturday and spreading east
Saturday night. The activity will linger through the rest of the
weekend and into early next week. Looks like best chances will be
Sunday night and Monday.

Byrd

&&

.AVIATION:  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1126 PM CDT Tue Apr 22 2014

VFR flight conditions expected through the forecast period with
clear skies or scattered mid-hi clouds overnight and mid-high
clouds on Wednesday. Light winds tonight will become southeasterly
and increase on Wednesday morning.

Specifics for KSTL:

VFR flight conditions expected through the forecast period with
clear skies or scattered mid-hi clouds overnight and mid-high
clouds on Wednesday. Light winds tonight will become southeasterly
and increase on Wednesday morning.

Glass

&&

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

$$

WFO LSX








000
FXUS63 KLSX 222225
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
525 PM CDT Tue Apr 22 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 259 PM CDT Tue Apr 22 2014

Surface ridge to move off to the east tonight allowing southerly
winds to return to the region by Wednesday. In the meantime, clear
skies and light north winds to prevail tonight. Lows will drop into
the low to mid 40s.

Byrd

.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 259 PM CDT Tue Apr 22 2014

On Wednesday, mid and high clouds will be on the increase as next
weather system approaches region. With southeast to south winds
temperatures to warm up into the mid 60s to mid 70s.

As for precipitation chances, feel that there is a lot of dry air to
overcome, so best chances for showers and thunderstorms will be on
Thursday as cold front swings through region. Not a lot of
instability with this system with highest capes, around 500 j/kg,
especially along and south of I-70. Activity to exit area Thursday
evening. Highs on Thursday will depend on cloud cover, precipitation
and timing of cold front. For now have mid 60s to low 70s.

Not a lot of caa behind this system and will see a secondary frontal
boundary slide south through region on Friday stalling out well
south of forecast area. Do not anticipate any precipitation with
this boundary, but will become the focus of activity later in the
weekend and into early next week for our area. Highs on Friday will
be in the 70s.

Extended models still have timing and placement issues with
activity. For now have showers and thunderstorms developing across
western portions of forecast area on Saturday and spreading east
Saturday night. The activity will linger through the rest of the
weekend and into early next week. Looks like best chances will be
Sunday night and Monday.

Byrd

&&

.AVIATION:  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 522 PM CDT Tue Apr 22 2014

VFR flight conditions expected through the forecast period with
clear skies or scattered mid-hi clouds tonight and increasing mid-
hi clouds on Wednesday morning. Surface high dominating the area
will bring light winds tonight, becoming southeasterly 8-13 kts on
Wednesday morning.

Specifics for KSTL:

VFR flight conditions expected through the forecast period with
clear skies or scattered mid-hi clouds tonight and increasing mid-
hi clouds on Wednesday morning. Surface high dominating the area
will bring light winds tonight, becoming southeasterly 10-13 kts on
Wednesday morning.

Glass

&&

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

$$

WFO LSX








000
FXUS63 KLSX 222000
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
300 PM CDT Tue Apr 22 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 259 PM CDT Tue Apr 22 2014

Surface ridge to move off to the east tonight allowing southerly
winds to return to the region by Wednesday. In the meantime, clear
skies and light north winds to prevail tonight. Lows will drop into
the low to mid 40s.

Byrd

.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 259 PM CDT Tue Apr 22 2014

On Wednesday, mid and high clouds will be on the increase as next
weather system approaches region. With southeast to south winds
temperatures to warm up into the mid 60s to mid 70s.

As for precipitation chances, feel that there is a lot of dry air to
overcome, so best chances for showers and thunderstorms will be on
Thursday as cold front swings through region. Not a lot of
instability with this system with highest capes, around 500 j/kg,
especially along and south of I-70. Activity to exit area Thursday
evening. Highs on Thursday will depend on cloud cover, precipitation
and timing of cold front. For now have mid 60s to low 70s.

Not a lot of caa behind this system and will see a secondary frontal
boundary slide south through region on Friday stalling out well
south of forecast area. Do not anticipate any precipitation with
this boundary, but will become the focus of activity later in the
weekend and into early next week for our area. Highs on Friday will
be in the 70s.

Extended models still have timing and placement issues with
activity. For now have showers and thunderstorms developing across
western portions of forecast area on Saturday and spreading east
Saturday night. The activity will linger through the rest of the
weekend and into early next week. Looks like best chances will be
Sunday night and Monday.

Byrd
&&

.AVIATION:  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1057 AM CDT Tue Apr 22 2014

Surface ridge extending from MN s-sw into OK will move eastward
through our area. The n-nwly surface wind will weaken this evening
and veer around to an e-nely direction. The wind will strengthen on
Wednesday from a sely direction as the surface ridge axis shifts
east of our area. There may be some high level clouds late
tonight, then mid level clouds will develop and move eastward
through northeast MO and west central IL on Wednesday due to
strong low-mid level warm air advection.

Specifics for KSTL: N-nwly surface wind will weaken this evening
and become light late tonight. The wind will increase again to
around 10 kts Wednesday afternoon from a sely direction. Just
some high level clouds late tonight, then mid level clouds on
Wednesday.

GKS
&&

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

$$
WFO LSX






000
FXUS63 KLSX 221636
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1136 AM CDT Tue Apr 22 2014

.SHORT TERM: (Today through Thursday)
Issued at 348 AM CDT Tue Apr 22 2014

Cold front extending from near Effingham IL southwest to near
West Plains MO. The cooler and drier air is lagging the wind shift
a bit and is just now working into central and eastern Missouri.
Pretty solid ridge behind the front is progged to build southeast
into the Mississippi Valley today. Looking back to yesterday,
highs across northern and eastern Nebraska, southern South Dakota,
and western Iowa ranged from the mid 60s to low 70s. This is
agreeable with latest MOS guidance...but with plenty of sunshine
expected today and the recent trend of MOS to be a little too
cool, I went just a degree or two higher. With wind dropping off
and a clear sky tonight, should see excellent radiational cooling
conditions develop, especially along and east of the Mississippi
River which will be closest to the ridge axis. MOS guidance is
pretty uniformly in the 40 to 45 degree range for lows tonight,
but would not be surprised to see some of our cold spots drop into
the upper 30s.

Should see the wind turn back around to the southeast on Wednesday
ahead of a strong trof of low pressure which will develop over the
Great Plains.  850mb temperatures jump back up to 8-12C by 00Z
Though forecast soundings across the area don`t mix quite that high,
i did bump high temperatures up a little over MOS to try to account
for the good warm advection.  The trof will move into the eastern
Plains and upper Midwest Wednesday night.   A 40-50kt low level jet
develops ahead of the trof over the Mississippi Valley between
06-12Z Thursday, and models show good mass convergence across the
CWFA by 12Z on the nose of this jet in the baroclinic zone.  Start
time of precipitation is still in question, though with all that
convergence over the area by 12Z would think that something should
be moving into the area by then.  Stuck with high chance PoPs in
central and northeast Missouri to account for this after 06Z
Thursday to account for this even though guidance came in a little
drier.  Thursday still looks wet as the cold front pushes through
the area so have maintained likely PoPs across the area.  While
there should be plenty of deep layer shear, widespread severe
weather looks unlikely at this time due to limited heating and
therefore low CAPE values

Carney

.LONG TERM: (Friday through Monday)
Issued at 348 AM CDT Tue Apr 22 2014

Latest runs of the medium range models are in better agreement than
yesterday`s.  The GFS and ECMWF are now pretty darn close with the
cold front from Thursday`s system only making int into central
Arkansas on Friday and then moving back to the north into southern
Missouri by Saturday.  Resulting low level baroclinic zone sets up
across Missouri and by 00Z Sunday a 30+ kt low level jet is pointing
at it.  Both models develop a wide area of moisture convergence
along the baroclinic zone as a result and print out fairly wide
spread precip.  Strong baroclinicity hangs over the area through
Monday with waves of precipitation as a strong negatively tilted
upper level longwave trof moves across the Rockies into the Plains.
This could be a very wet and stormy pattern for Saturday night into
Monday.  However, since these are the first runs I`ve seen to
actually agree fairly well, I haven`t bitten hook-line-and-sinker on
them yet.  That being said I did bump up pops a bit to account for
the better model agreement.  Temperatures will be highly dependent
on where the surface front sets up and how it moves through the
weekend.  Needless to say, the Saturday through Monday time period
is still a low confidence forecast.

Carney

&&

.AVIATION:  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1057 AM CDT Tue Apr 22 2014

Surface ridge extending from MN s-sw into OK will move eastward
through our area. The n-nwly surface wind will weaken this evening
and veer around to an e-nely direction. The wind will strengthen on
Wednesday from a sely direction as the surface ridge axis shifts
east of our area. There may be some high level clouds late
tonight, then mid level clouds will develop and move eastward
through northeast MO and west central IL on Wednesday due to
strong low-mid level warm air advection.

Specifics for KSTL: N-nwly surface wind will weaken this evening
and become light late tonight. The wind will increase again to
around 10 kts Wednesday afternoon from a sely direction. Just
some high level clouds late tonight, then mid level clouds on
Wednesday.

GKS

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     69  45  71  52 /   0   0   5  10
Quincy          66  43  67  51 /   0   0  10  40
Columbia        68  45  71  54 /   0   0   5  40
Jefferson City  69  45  73  54 /   0   0   5  40
Salem           68  41  66  48 /   0   0   5  10
Farmington      68  43  70  50 /   5   0   0  10

&&

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

$$

WFO LSX








000
FXUS63 KLSX 221049
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
549 AM CDT Tue Apr 22 2014

.SHORT TERM: (Today through Thursday)
Issued at 348 AM CDT Tue Apr 22 2014

Cold front extending from near Effingham IL southwest to near
West Plains MO. The cooler and drier air is lagging the wind shift
a bit and is just now working into central and eastern Missouri.
Pretty solid ridge behind the front is progged to build southeast
into the Mississippi Valley today. Looking back to yesterday,
highs across northern and eastern Nebraska, southern South Dakota,
and western Iowa ranged from the mid 60s to low 70s. This is
agreeable with latest MOS guidance...but with plenty of sunshine
expected today and the recent trend of MOS to be a little too
cool, I went just a degree or two higher. With wind dropping off
and a clear sky tonight, should see excellent radiational cooling
conditions develop, especially along and east of the Mississippi
River which will be closest to the ridge axis. MOS guidance is
pretty uniformly in the 40 to 45 degree range for lows tonight,
but would not be surprised to see some of our cold spots drop into
the upper 30s.

Should see the wind turn back around to the southeast on Wednesday
ahead of a strong trof of low pressure which will develop over the
Great Plains.  850mb temperatures jump back up to 8-12C by 00Z
Though forecast soundings across the area don`t mix quite that high,
i did bump high temperatures up a little over MOS to try to account
for the good warm advection.  The trof will move into the eastern
Plains and upper Midwest Wednesday night.   A 40-50kt low level jet
develops ahead of the trof over the Mississippi Valley between
06-12Z Thursday, and models show good mass convergence across the
CWFA by 12Z on the nose of this jet in the baroclinic zone.  Start
time of precipitation is still in question, though with all that
convergence over the area by 12Z would think that something should
be moving into the area by then.  Stuck with high chance PoPs in
central and northeast Missouri to account for this after 06Z
Thursday to account for this even though guidance came in a little
drier.  Thursday still looks wet as the cold front pushes through
the area so have maintained likely PoPs across the area.  While
there should be plenty of deep layer shear, widespread severe
weather looks unlikely at this time due to limited heating and
therefore low CAPE values


Carney

.LONG TERM: (Friday through Monday)
Issued at 348 AM CDT Tue Apr 22 2014

Latest runs of the medium range models are in better agreement than
yesterday`s.  The GFS and ECMWF are now pretty darn close with the
cold front from Thursday`s system only making int into central
Arkansas on Friday and then moving back to the north into southern
Missouri by Saturday.  Resulting low level baroclinic zone sets up
across Missouri and by 00Z Sunday a 30+ kt low level jet is pointing
at it.  Both models develop a wide area of moisture convergence
along the baroclinic zone as a result and print out fairly wide
spread precip.  Strong baroclinicity hangs over the area through
Monday with waves of precipitation as a strong negatively tilted
upper level longwave trof moves across the Rockies into the Plains.
This could be a very wet and stormy pattern for Saturday night into
Monday.  However, since these are the first runs I`ve seen to
actually agree fairly well, I haven`t bitten hook-line-and-sinker on
them yet.  That being said I did bump up pops a bit to account for
the better model agreement.  Temperatures will be highly dependent
on where the surface front sets up and how it moves through the
weekend.  Needless to say, the Saturday through Monday time period
is still a low confidence forecast.

Carney

&&

.AVIATION:  (For the 12z TAFs through 12z Wednesday Morning)
Issued at 544 AM CDT Tue Apr 22 2014

Dry, VFR flight conditions will prevail across all TAF sites.
North-northwesterly winds generally between 10-15KT will decrease
after sunset and gradually veer to the northeast by the end of
the forecast period.

Specifics for KSTL:
Dry, VFR flight conditions will prevail through the period, with
northwest winds between 10-15KT decreasing after sunset and
gradually veering to the northeast by Wednesday morning.

JP

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     69  46  70  52 /   0   0   5  10
Quincy          66  42  68  50 /   0   0  10  40
Columbia        68  45  73  54 /   0   0   5  40
Jefferson City  69  43  74  54 /   0   0   5  40
Salem           68  42  67  50 /   0   0   5  10
Farmington      68  41  71  49 /   5   0   0  10

&&

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

$$

WFO LSX








000
FXUS63 KLSX 220850
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
350 AM CDT Tue Apr 22 2014

.SHORT TERM: (Today through Thursday)
Issued at 348 AM CDT Tue Apr 22 2014

Cold front extending from near Effingham IL southwest to near
West Plains MO. The cooler and drier air is lagging the wind shift
a bit and is just now working into central and eastern Missouri.
Pretty solid ridge behind the front is progged to build southeast
into the Mississippi Valley today. Looking back to yesterday,
highs across northern and eastern Nebraska, southern South Dakota,
and western Iowa ranged from the mid 60s to low 70s. This is
agreeable with latest MOS guidance...but with plenty of sunshine
expected today and the recent trend of MOS to be a little too
cool, I went just a degree or two higher. With wind dropping off
and a clear sky tonight, should see excellent radiational cooling
conditions develop, especially along and east of the Mississippi
River which will be closest to the ridge axis. MOS guidance is
pretty uniformly in the 40 to 45 degree range for lows tonight,
but would not be surprised to see some of our cold spots drop into
the upper 30s.

Should see the wind turn back around to the southeast on Wednesday
ahead of a strong trof of low pressure which will develop over the
Great Plains.  850mb temperatures jump back up to 8-12C by 00Z
Though forecast soundings across the area don`t mix quite that high,
i did bump high temperatures up a little over MOS to try to account
for the good warm advection.  The trof will move into the eastern
Plains and upper Midwest Wednesday night.   A 40-50kt low level jet
develops ahead of the trof over the Mississippi Valley between
06-12Z Thursday, and models show good mass convergence across the
CWFA by 12Z on the nose of this jet in the baroclinic zone.  Start
time of precipitation is still in question, though with all that
convergence over the area by 12Z would think that something should
be moving into the area by then.  Stuck with high chance PoPs in
central and northeast Missouri to account for this after 06Z
Thursday to account for this even though guidance came in a little
drier.  Thursday still looks wet as the cold front pushes through
the area so have maintained likely PoPs across the area.  While
there should be plenty of deep layer shear, widespread severe
weather looks unlikely at this time due to limited heating and
therefore low CAPE values


Carney

.LONG TERM: (Friday through Monday)
Issued at 348 AM CDT Tue Apr 22 2014

Latest runs of the medium range models are in better agreement than
yesterday`s.  The GFS and ECMWF are now pretty darn close with the
cold front from Thursday`s system only making int into central
Arkansas on Friday and then moving back to the north into southern
Missouri by Saturday.  Resulting low level baroclinic zone sets up
across Missouri and by 00Z Sunday a 30+ kt low level jet is pointing
at it.  Both models develop a wide area of moisture convergence
along the baroclinic zone as a result and print out fairly wide
spread precip.  Strong baroclinicity hangs over the area through
Monday with waves of precipitation as a strong negatively tilted
upper level longwave trof moves across the Rockies into the Plains.
This could be a very wet and stormy pattern for Saturday night into
Monday.  However, since these are the first runs I`ve seen to
actually agree fairly well, I haven`t bitten hook-line-and-sinker on
them yet.  That being said I did bump up pops a bit to account for
the better model agreement.  Temperatures will be highly dependent
on where the surface front sets up and how it moves through the
weekend.  Needless to say, the Saturday through Monday time period
is still a low confidence forecast.

Carney

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1149 PM CDT Mon Apr 21 2014

Fog has developed across the region in areas where winds have
become calm and skies were starting to clear. The lower dew points
behind the cold front were filtering in to the region and wind
speeds were also increasing. These two factors will interfere with
fog formation with visibilities likely improving over the next
couple of hours once the front has moved through. Until then,
expect visibilities to vary from IFR (favored low spots and TAF
sites near rivers such as KSUS) to VFR. After the fog has
dissipated, VFR conditions are anticipated for the remainder of
the TAF period.

Kanofsky

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     69  46  70  52 /   0   0   5  10
Quincy          66  42  68  50 /   0   0  10  40
Columbia        68  45  73  54 /   0   0   5  40
Jefferson City  69  43  74  54 /   0   0   5  40
Salem           68  42  67  50 /   0   0   5  10
Farmington      68  41  71  49 /   5   0   0  10

&&

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

$$

WFO LSX








000
FXUS63 KLSX 220458
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1158 PM CDT Mon Apr 21 2014

.UPDATE:
Issued at 842 PM CDT Mon Apr 21 2014

Band of showers along the cold front will continue to weaken as
they move southeast through 06Z.

CVKING

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 311 PM CDT Mon Apr 21 2014

Cold front has moved into Missouri and will continue to track to the
southeast this evening. Showers and some thunderstorms have
developed ahead of cold front, but they will remain scattered in
nature before coming to an end late this evening. As for
temperatures, not a lot of caa behind this front so will have lows
in the mid 40s to mid 50s.

Byrd

.LONG TERM:  (Tuesday through Next Monday)
Issued at 311 PM CDT Mon Apr 21 2014

Skies to clear out by daybreak on Tuesday with north winds
persisting throughout the day. So a bit chillier but highs will be
in the mid 60s to low 70s.

Then surface ridge to move off to the east by Wednesday allowing
southerly winds to return ahead of next weather system. Highs on
Wednesday will be in the upper 60s to mid 70s.

Showers and thunderstorms to develop along frontal boundary late
Wednesday night and spread east. Best chances of precipitation will
be during the day on Thursday. Front to move through during the
afternoon and evening hours with decent instability, i.e.
surface based capes between 500 and 1000 j/kg and deep layer shear
in excess of 40kts.  However, unsure yet what the severe potential
will be. As for highs on Thursday, they will be in the upper 60s to
low 70s.

Beyond that, next chance for precipitation will be Saturday night
through Monday. But extended models have timing and placement
issues, so no major changes at this time.

Byrd

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1149 PM CDT Mon Apr 21 2014

Fog has developed across the region in areas where winds have
become calm and skies were starting to clear. The lower dew points
behind the cold front were filtering in to the region and wind
speeds were also increasing. These two factors will interfere with
fog formation with visibilities likely improving over the next
couple of hours once the front has moved through. Until then,
expect visibilities to vary from IFR (favored low spots and TAF
sites near rivers such as KSUS) to VFR. After the fog has
dissipated, VFR conditions are anticipated for the remainder of
the TAF period.

Kanofsky

&&

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

$$

WFO LSX








000
FXUS63 KLSX 220144
AFDLSX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ST LOUIS MO
844 PM CDT Mon Apr 21 2014

.UPDATE:
Issued at 842 PM CDT Mon Apr 21 2014

Band of showers along the cold front will continue to weaken as
they move southeast through 06Z.

CVKING

&&

.SHORT TERM:  (Through Late Tonight)
Issued at 311 PM CDT Mon Apr 21 2014

Cold front has moved into Missouri and will continue to track to the
southeast this evening. Showers and some thunderstorms have
developed ahead of cold front, but they will remain scattered in
nature before coming to an end late this evening. As for
temperatures, not a lot of caa behind this front so will have lows
in the mid 40s to mid 50s.

Byrd

.LONG TERM:  (Tuesday through Next Monday)
Issued at 311 PM CDT Mon Apr 21 2014

Skies to clear out by daybreak on Tuesday with north winds
persisting throughout the day. So a bit chillier but highs will be
in the mid 60s to low 70s.

Then surface ridge to move off to the east by Wednesday allowing
southerly winds to return ahead of next weather system. Highs on
Wednesday will be in the upper 60s to mid 70s.

Showers and thunderstorms to develop along frontal boundary late
Wednesday night and spread east. Best chances of precipitation will
be during the day on Thursday. Front to move through during the
afternoon and evening hours with decent instability, i.e.
surface based capes between 500 and 1000 j/kg and deep layer shear
in excess of 40kts.  However, unsure yet what the severe potential
will be. As for highs on Thursday, they will be in the upper 60s to
low 70s.

Beyond that, next chance for precipitation will be Saturday night
through Monday. But extended models have timing and placement
issues, so no major changes at this time.

Byrd

&&

.AVIATION:  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 622 PM CDT Mon Apr 21 2014

Specifics for KCOU, KUIN: Expect variable flight conditions over
the next 6 hours with improvement expected by 9-12 hours at the
latest. An area of SHRA/TSRA was affecting KCOU at TAF issuance
and a second line was located north and west of KUIN. This second
line is associated with a cold front and will probably move
through KUIN, but instability might not be sufficient for it to
reach KCOU. The additional low-level moisture provided by
scattered SHRA/TSRA could help ceilings lower to MVFR for a couple
of hours this evening until the cold front moves through later
tonight. Winds become northwest to north after FROPA.

Specifics for KSTL, KSUS, KCPS: Expect variable flight conditions
over the next 6 hours with improvement expected by 9-12 hours. An
area of SHRA/TSRA stretched roughly from KCOU to KPPQ at TAF
issuance and was moving southeastward. Some spotty showers are
possible at metro area TAF sites before this broader area of
precip reaches the terminals. A second line of SHRA/TSRA was
located farther northwest and was associated with a cold front.
There is some question about whether or not the instability will
be sufficient for this line to hold together long enough to reach
KSTL/KSUS/KCPS. The additional low-level moisture provided by
scattered SHRA/TSRA could help ceilings lower to MVFR for a couple
of hours this evening until the cold front moves through
overnight. Winds become northwest to north after FROPA.

Kanofsky

&&

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

$$

WFO LSX








000
FXUS63 KLSX 212348
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
648 PM CDT Mon Apr 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 311 PM CDT Mon Apr 21 2014

Cold front has moved into Missouri and will continue to track to the
southeast this evening. Showers and some thunderstorms have
developed ahead of cold front, but they will remain scattered in
nature before coming to an end late this evening. As for
temperatures, not a lot of caa behind this front so will have lows
in the mid 40s to mid 50s.

Byrd

.LONG TERM:  (Tuesday through Next Monday)
Issued at 311 PM CDT Mon Apr 21 2014

Skies to clear out by daybreak on Tuesday with north winds
persisting throughout the day. So a bit chillier but highs will be
in the mid 60s to low 70s.

Then surface ridge to move off to the east by Wednesday allowing
southerly winds to return ahead of next weather system. Highs on
Wednesday will be in the upper 60s to mid 70s.

Showers and thunderstorms to develop along frontal boundary late
Wednesday night and spread east. Best chances of precipitation will
be during the day on Thursday. Front to move through during the
afternoon and evening hours with decent instability, i.e.
surface based capes between 500 and 1000 j/kg and deep layer shear
in excess of 40kts.  However, unsure yet what the severe potential
will be. As for highs on Thursday, they will be in the upper 60s to
low 70s.

Beyond that, next chance for precipitation will be Saturday night
through Monday. But extended models have timing and placement
issues, so no major changes at this time.

Byrd

&&

.AVIATION:  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 622 PM CDT Mon Apr 21 2014

Specifics for KCOU, KUIN: Expect variable flight conditions over
the next 6 hours with improvement expected by 9-12 hours at the
latest. An area of SHRA/TSRA was affecting KCOU at TAF issuance
and a second line was located north and west of KUIN. This second
line is associated with a cold front and will probably move
through KUIN, but instability might not be sufficient for it to
reach KCOU. The additional low-level moisture provided by
scattered SHRA/TSRA could help ceilings lower to MVFR for a couple
of hours this evening until the cold front moves through later
tonight. Winds become northwest to north after FROPA.

Specifics for KSTL, KSUS, KCPS: Expect variable flight conditions
over the next 6 hours with improvement expected by 9-12 hours. An
area of SHRA/TSRA stretched roughly from KCOU to KPPQ at TAF
issuance and was moving southeastward. Some spotty showers are
possible at metro area TAF sites before this broader area of
precip reaches the terminals. A second line of SHRA/TSRA was
located farther northwest and was associated with a cold front.
There is some question about whether or not the instability will
be sufficient for this line to hold together long enough to reach
KSTL/KSUS/KCPS. The additional low-level moisture provided by
scattered SHRA/TSRA could help ceilings lower to MVFR for a couple
of hours this evening until the cold front moves through
overnight. Winds become northwest to north after FROPA.

Kanofsky

&&

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

$$

WFO LSX








000
FXUS63 KLSX 212011
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
311 PM CDT Mon Apr 21 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 311 PM CDT Mon Apr 21 2014

Cold front has moved into Missouri and will continue to track to the
southeast this evening. Showers and some thunderstorms have
developed ahead of cold front, but they will remain scattered in
nature before coming to an end late this evening. As for
temperatures, not a lot of caa behind this front so will have lows
in the mid 40s to mid 50s.

Byrd

.LONG TERM:  (Tuesday through Next Monday)
Issued at 311 PM CDT Mon Apr 21 2014

Skies to clear out by daybreak on Tuesday with north winds
persisting throughout the day. So a bit chillier but highs will be
in the mid 60s to low 70s.

Then surface ridge to move off to the east by Wednesday allowing
southerly winds to return ahead of next weather system. Highs on
Wednesday will be in the upper 60s to mid 70s.

Showers and thunderstorms to develop along frontal boundary late
Wednesday night and spread east. Best chances of precipitation will
be during the day on Thursday. Front to move through during the
afternoon and evening hours with decent instability, i.e.
surface based capes between 500 and 1000 j/kg and deep layer shear
in excess of 40kts.  However, unsure yet what the severe potential
will be. As for highs on Thursday, they will be in the upper 60s to
low 70s.

Beyond that, next chance for precipitation will be Saturday night
through Monday. But extended models have timing and placement
issues, so no major changes at this time.

Byrd
&&

.AVIATION:  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1056 AM CDT Mon Apr 21 2014

At least scattered showers and thunderstorms are expected this
afternoon into the early evening hours as an upper level
disturbance moves eastward through the region, while a cold front
moves southeastward through the taf sites late this afternoon and
this evening. Looking at the latest radar trends it appears that
most of the shower activity early this afternoon should occur in
the UIN area, but showers and storms should develop in the COU
area later this afternoon and move through the St Louis metro area
particularly during the early evening hours. Although prevailing
conditions have been VFR outside of the showers so far, some of
the MVFR cigs over western MO will likely advect into the region
later this afternoon, plus there will likely be some MVFR cigs
just behind the cold front. Mainly southwesterly winds will veer
around to a northwesterly direction after fropa. The clouds
should clear out fairly quickly this evening in UIN and COU and
overnight in the St Louis metro area as a relatively strong
surface ridge builds southeastward into the region behind the cold
front.

Specifics for KSTL: Looks like a break in the shower activity
early this afternoon, but model guidance indicates that showers
and storms will develop and move through the STL area late this
afternoon and early this evening. These showers and storms should
shift southeast of STL by 04z Tuesday after fropa with the wind
veering around to a northwesterly direction. Will have VFR
conditions early this afternoon until the showers and storms move
into the area with the lowest prevailing cloud ceilings likely
this evening, possibly briefly down to around 1000-2000 ft. The
clouds should clear out shortly after 06z Tuesday.

GKS
&&

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

$$
WFO LSX






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