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000
FXUS63 KLSX 290817
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
317 AM CDT FRI APR 29 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 315 AM CDT Fri Apr 29 2016

Mid and high clouds from next system already streaming across
forecast area early this morning. But with dry east flow at surface,
it will take some time for the moisture to return. Instability will
be marginal as well. So mainly showers and a few thunderstorms will
develop over southern/western Missouri and increase in coverage to
the northeast. Otherwise, temperatures will be near normal in the
low 60s to around 70 for highs.

Byrd

.LONG TERM...  (Tonight through Thursday)
Issued at 315 AM CDT Fri Apr 29 2016

Models still have some placement issues with the area of low
pressure with the NAM further north than the GFS, and the ECMWF
somewhere in between. For now feel that warm front to develop and
lift north across forecast area tonight, stalling out along the
I70 corridor. Decent low level jet helping to bring in plenty of
moisture and will see elevated convection develop and track east
northeast across forecast area.

On Saturday, if system is further north we could see more of a
severe weather threat. With surface dewpts in the low to mid 60s,
will see surface based CAPES in excess of 2000 J/kg, but shear will
be weak. So SPC has placed areas along and south of I70 in a slight
risk for Saturday with the main threat being large hail.

All models are indicating closed upper level low to open up and lift
out late Saturday night and Sunday with rain coming to an end by
Sunday evening.

For the rest of the forecast period, it looks to be dry as a surface
ridge builds in. Will see some weak upper level shortwaves slide
across southern portions of the forecast area through this period,
but little in the way of precipitation is expected. Temperatures
will be a bit below normal on Monday, but expect highs in the low to
mid 70s by Wednesday and Thursday.

Byrd
&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1101 PM CDT Thu Apr 28 2016

The low level cloudiness over UIN has been shifting slowly
northward this evening and may actually clear out of UIN, at
least briefly overnight. May have a period of MVFR cigs early
Friday morning at UIN. Further south, just high level cloudiness
will spread into the taf sites late tonight. VFR, low-mid level
cloudiness will move into COU and the St Louis metro area by
Friday afternoon as moisture spreads into the area ahead of an
approaching storm system in the southern Plains and north of a
warm front. Showers may move into COU and the St Louis metro area
as early as Friday afternoon, but more likely Friday evening. Cigs
and vsbys may lower into the MVFR category Friday evening with
these showers and as the low levels saturate. Weak northwest
surface winds will veer around to an easterly direction by Friday
afternoon as they gradually strengthen.

Specifics for KSTL: Light surface wind will gradually veer around
to an easterly direction and increase to around 8-10 kts Friday
afternoon. Just some high level clouds spreading into STL late
tonight and Friday morning, then the cloud ceiling will gradually
lower Friday afternoon and night as showers move into STL late
Friday afternoon or evening. Cigs and vsbys will lower into the
MVFR category Friday night.

GKS

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     70  58  74  56 /  20  80  80  50
Quincy          66  52  64  49 /  10  70  80  50
Columbia        67  56  74  52 /  40  80  60  50
Jefferson City  69  58  76  54 /  40  80  60  50
Salem           69  57  72  57 /  10  80  80  50
Farmington      68  57  76  56 /  40  80  70  50

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$
WFO LSX





000
FXUS63 KLSX 290421
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1121 PM CDT THU APR 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 339 PM CDT Thu Apr 28 2016

Still expect a dry night as upper ridge approaches the area from the
west and surface low moves over Indiana moves off to the east.
Clouds currently across northern Missouri and central Illinois will
slowly move south through the night as the low moves to the east.
Lows tonight will be slightly cooler than MOS guidance, particularly
where clouds have kept temperatures down today.

Britt

.LONG TERM...  (Friday through Next Thursday)
Issued at 339 PM CDT Thu Apr 28 2016

...Friday through Sunday...

Not too much change to going forecast as showers and thunderstorms
will begin to overspread the area on Friday.  It still appears that
likely or categorical PoPs will be needed Friday night into
Saturday morning as strong moisture convergence will lie
underneath decent ascent ahead of mid level trough. There is some
differences between the ECMWF/NAM vs. the GFS with the ECMWF/NAM
showing a slightly more northerly track with the surface low on
Saturday evening than the GFS. The ECMWF/GFS could bring more of a
severe weather threat, so will need to watch this closely. The
chance of thunderstorms will linger into Sunday before the upper
low moves out of the area.

...Monday through Thursday...

While the details differ, the overall idea of the GFS and ECMWF
is the same with the upper pattern becoming more amplified next
week.  Shortwave trough will move southeast out of the Canada early
next week and phase with upper trough moving east out of the
southwest CONUS. This will cause northwesterly flow aloft to
develop by midweek. Rain chances look minimal at this point in the
northwesterly flow with near normal temperatures as the GFS Mean
ensemble and the ECMWF 850mb temperatures will be in the 5-10C
range.

Britt

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1101 PM CDT Thu Apr 28 2016

The low level cloudiness over UIN has been shifting slowly
northward this evening and may actually clear out of UIN, at
least briefly overnight. May have a period of MVFR cigs early
Friday morning at UIN. Further south, just high level cloudiness
will spread into the taf sites late tonight. VFR, low-mid level
cloudiness will move into COU and the St Louis metro area by
Friday afternoon as moisture spreads into the area ahead of an
approaching storm system in the southern Plains and north of a
warm front. Showers may move into COU and the St Louis metro area
as early as Friday afternoon, but more likely Friday evening. Cigs
and vsbys may lower into the MVFR catagory Friday evening with
these showers and as the low levels saturate. Weak northwest
surface winds will veer around to an easterly direction by Friday
afternoon as they gradually strengthen.

Specifics for KSTL: Light surface wind will gradually veer around
to an easterly direction and increase to around 8-10 kts Friday
afternoon. Just some high level clouds spreading into STL late
tonight and Friday morning, then the cloud ceiling will gradually
lower Friday afternoon and night as showers move into STL late
Friday afternoon or evening. Cigs and vsbys will lower into the
MVFR catagory Friday night.

GKS

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 282301
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
601 PM CDT THU APR 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 339 PM CDT Thu Apr 28 2016

Still expect a dry night as upper ridge approaches the area from the
west and surface low moves over Indiana moves off to the east.
Clouds currently across northern Missouri and central Illinois will
slowly move south through the night as the low moves to the east.
Lows tonight will be slightly cooler than MOS guidance, particularly
where clouds have kept temperatures down today.

Britt

.LONG TERM...  (Friday through Next Thursday)
Issued at 339 PM CDT Thu Apr 28 2016

...Friday through Sunday...

Not too much change to going forecast as showers and thunderstorms
will begin to overspread the area on Friday.  It still appears that
likely or categorical PoPs will be needed Friday night into
Saturday morning as strong moisture convergence will lie
underneath decent ascent ahead of mid level trough. There is some
differences between the ECMWF/NAM vs. the GFS with the ECMWF/NAM
showing a slightly more northerly track with the surface low on
Saturday evening than the GFS. The ECMWF/GFS could bring more of a
severe weather threat, so will need to watch this closely. The
chance of thunderstorms will linger into Sunday before the upper
low moves out of the area.

...Monday through Thursday...

While the details differ, the overall idea of the GFS and ECMWF
is the same with the upper pattern becoming more amplified next
week.  Shortwave trough will move southeast out of the Canada early
next week and phase with upper trough moving east out of the
southwest CONUS. This will cause northwesterly flow aloft to
develop by midweek. Rain chances look minimal at this point in the
northwesterly flow with near normal temperatures as the GFS Mean
ensemble and the ECMWF 850mb temperatures will be in the 5-10C
range.

Britt

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 527 PM CDT Thu Apr 28 2016

Low level cloudiness will continue at UIN tonight and Friday with
the ceiling dropping into the MVFR catagory late tonight and
continuing MVFR at least through the morning hours. It appears
that these low level clouds will remain north of COU and the St
Louis metro area tonight. VFR, low-mid level cloudiness will
spread into COU and the St Louis metro area by Friday afternoon as
moisture spreads into the area ahead of an approaching storm
system in the southern Plains and north of a warm front. Showers
may move into COU and the St Louis metro area as early as Friday
afternoon, but more likely Friday evening. West-northwest surface
winds will become light this evening, then veer around to an
easterly direction by Friday afternoon as they gradually
strengthen.

Specifics for KSTL: Northwest wind will become light this evening,
then gradually veer around to an easterly direction and increase
to around 8-10 kts Friday afternoon. Just some mid-high level
clouds tonight and Friday morning, then the cloud ceiling will
gradually lower Friday afternoon and evening as showers move into
STL late Friday afternoon or evening. Cigs and vsbys may lower
into the MVFR catagory Friday evening with these showers and as
the low levels saturate.

GKS

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 282045
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
345 PM CDT THU APR 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 339 PM CDT Thu Apr 28 2016

Still expect a dry night as upper ridge approaches the area from the
west and surface low moves over Indiana moves off to the east.
Clouds currently across northern Missouri and central Illinois will
slowly move south through the night as the low moves to the east.
Lows tonight will be slightly cooler than MOS guidance, particularly
where clouds have kept temperatures down today.

Britt

.LONG TERM...  (Friday through Next Thursday)
Issued at 339 PM CDT Thu Apr 28 2016

...Friday through Sunday...

Not too much change to going forecast as showers and thunderstorms
will begin to overspread the area on Friday.  It still appears that
likely or categorical PoPs will be needed Friday night into
Saturday morning as strong moisture convergence will lie
underneath decent ascent ahead of mid level trough. There is some
differences between the ECMWF/NAM vs. the GFS with the ECMWF/NAM
showing a slightly more northerly track with the surface low on
Saturday evening than the GFS. The ECMWF/GFS could bring more of a
severe weather threat, so will need to watch this closely. The
chance of thunderstorms will linger into Sunday before the upper
low moves out of the area.

...Monday through Thursday...

While the details differ, the overall idea of the GFS and ECMWF
is the same with the upper pattern becoming more amplified next
week.  Shortwave trough will move southeast out of the Canada early
next week and phase with upper trough moving east out of the
southwest CONUS. This will cause northwesterly flow aloft to
develop by midweek. Rain chances look minimal at this point in the
northwesterly flow with near normal temperatures as the GFS Mean
ensemble and the ECMWF 850mb temperatures will be in the 5-10C
range.


Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1235 PM CDT Thu Apr 28 2016

A rather large area of stratus covered the Upper MS Valley and
northern Plains into northern MO and through a good portion of
northern and central IL. The southern extent impacting KUIN was
located within cyclonic westerly low level flow, and stretched
just north and west of KCOU. KUIN will continue to see MVFR flight
conditions this afternoon which are expected to improve to VFR by
00z. Overnight however lower stratus and some light fog will
likely move back into KUIN and persist into Friday morning.
Elsewhere predominately VFR flight conditions are expected with
potential for MVFR stratus on and off at KCOU through late
afternoon.

Specifics for KSTL:

VFR flight conditions are expected through the forecast TAF
period. Westerly winds this afternoon will become light this
evening and veer with time.

Glass

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 282045
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
345 PM CDT THU APR 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 339 PM CDT Thu Apr 28 2016

Still expect a dry night as upper ridge approaches the area from the
west and surface low moves over Indiana moves off to the east.
Clouds currently across northern Missouri and central Illinois will
slowly move south through the night as the low moves to the east.
Lows tonight will be slightly cooler than MOS guidance, particularly
where clouds have kept temperatures down today.

Britt

.LONG TERM...  (Friday through Next Thursday)
Issued at 339 PM CDT Thu Apr 28 2016

...Friday through Sunday...

Not too much change to going forecast as showers and thunderstorms
will begin to overspread the area on Friday.  It still appears that
likely or categorical PoPs will be needed Friday night into
Saturday morning as strong moisture convergence will lie
underneath decent ascent ahead of mid level trough. There is some
differences between the ECMWF/NAM vs. the GFS with the ECMWF/NAM
showing a slightly more northerly track with the surface low on
Saturday evening than the GFS. The ECMWF/GFS could bring more of a
severe weather threat, so will need to watch this closely. The
chance of thunderstorms will linger into Sunday before the upper
low moves out of the area.

...Monday through Thursday...

While the details differ, the overall idea of the GFS and ECMWF
is the same with the upper pattern becoming more amplified next
week.  Shortwave trough will move southeast out of the Canada early
next week and phase with upper trough moving east out of the
southwest CONUS. This will cause northwesterly flow aloft to
develop by midweek. Rain chances look minimal at this point in the
northwesterly flow with near normal temperatures as the GFS Mean
ensemble and the ECMWF 850mb temperatures will be in the 5-10C
range.


Britt

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1235 PM CDT Thu Apr 28 2016

A rather large area of stratus covered the Upper MS Valley and
northern Plains into northern MO and through a good portion of
northern and central IL. The southern extent impacting KUIN was
located within cyclonic westerly low level flow, and stretched
just north and west of KCOU. KUIN will continue to see MVFR flight
conditions this afternoon which are expected to improve to VFR by
00z. Overnight however lower stratus and some light fog will
likely move back into KUIN and persist into Friday morning.
Elsewhere predominately VFR flight conditions are expected with
potential for MVFR stratus on and off at KCOU through late
afternoon.

Specifics for KSTL:

VFR flight conditions are expected through the forecast TAF
period. Westerly winds this afternoon will become light this
evening and veer with time.

Glass

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 281747
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1247 PM CDT THU APR 28 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 333 AM CDT Thu Apr 28 2016

A stacked storm system was centered over western IA early this
morning.  At the surface, an occluded front extends southeast from
this storm center to a triple point in southwest IL, where a cold
front extends further south from there and a warm front extends east
from the triple point.  Temperatures were in the 60s ahead of the
cold front in southern IL, and have fallen into the 50s elsewhere.
Skies had also cleared over most areas, but some wraparound clouds
have recently moved back into sections of northwest MO.  A small
area of dense fog has developed just north of the front and triple
point, but the favorability to sustain this fog should decrease
heading towards dawn as the fronts move thru and the triple point
pulls away.

The surface triple point is expected to move out of the forecast
area into east-central IL by 12z this morning, taking the other
fronts out of the forecast area as well, leaving westerly flow in
its wake, and a surface TROF just to our north in southern IA and
central IL.  During this time, the storm center will track from
western IA into northeast IA with an upper level disturbance
will rotate thru southern IA by this afternoon.

The combination of some weak upper support and a surface boundary
and residual moisture should be enough for isolated to scattered
showers to develop with the heating of the day, but this all should
be just north of the forecast area.  Otherwise, clear skies are
expected for much of the area with additonal clouds in northeast MO
and west-central IL.  Westerly flow will support deep mixing,
resulting in max temps from the 60s in northern MO and central IL to
the 70s elsewhere.

TES

.LONG TERM...  (Tonight through Wednesday)
Issued at 333 AM CDT Thu Apr 28 2016

A weak sfc ridge builds into the area tonight, keeping the area dry
and cooler thru Fri morning.

The leading s/w may spread precip into the region as early as Fri
afternoon. Mdl differences continue with this system, but have
trended twd the slightly faster/more nrly ECMWF/NAM/local WRF solns.
This system will keep precip in the area thru much of the weekend,
tho Fri night thru Sat night still appears to be the bulk of the
precip. Given the mdl differences, uncertainty remains, but can not
rule out a severe threat on Sat. This threat will largely depend
upon where the sfc fnt sets up and if precip from overnight Fri can
move out of the area early enough for recovery.

Next week and beyond, sfc ridge builds into the area, keeping the
remainder of the forecast period largely dry. A secondary cdfnt
pushes thru the area sometime Wed. Mdls suggest this fnt will have
enuf moisture to generate precip, tho timing differences remain.
With Gulf cut off, do not believe enuf moisture will exist for
precip, but have kept low PoPs in for now.

Tilly

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1235 PM CDT Thu Apr 28 2016

A rather large area of stratus covered the Upper MS Valley and
northern Plains into northern MO and through a good portion of
northern and central IL. The southern extent impacting KUIN was
located within cyclonic westerly low level flow, and stretched
just north and west of KCOU. KUIN will continue to see MVFR flight
conditions this afternoon which are expected to improve to VFR by
00z. Overnight however lower stratus and some light fog will
likely move back into KUIN and persist into Friday morning.
Elsewhere predominately VFR flight conditions are expected with
potential for MVFR stratus on and off at KCOU through late
afternoon.

Specifics for KSTL:

VFR flight conditions are expected through the forecast TAF
period. Westerly winds this afternoon will become light this
evening and veer with time.

Glass

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 281145
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
645 AM CDT THU APR 28 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 333 AM CDT Thu Apr 28 2016

A stacked storm system was centered over western IA early this
morning.  At the surface, an occluded front extends southeast from
this storm center to a triple point in southwest IL, where a cold
front extends further south from there and a warm front extends east
from the triple point.  Temperatures were in the 60s ahead of the
cold front in southern IL, and have fallen into the 50s elsewhere.
Skies had also cleared over most areas, but some wraparound clouds
have recently moved back into sections of northwest MO.  A small
area of dense fog has developed just north of the front and triple
point, but the favorability to sustain this fog should decrease
heading towards dawn as the fronts move thru and the triple point
pulls away.

The surface triple point is expected to move out of the forecast
area into east-central IL by 12z this morning, taking the other
fronts out of the forecast area as well, leaving westerly flow in
its wake, and a surface TROF just to our north in southern IA and
central IL.  During this time, the storm center will track from
western IA into northeast IA with an upper level disturbance
will rotate thru southern IA by this afternoon.

The combination of some weak upper support and a surface boundary
and residual moisture should be enough for isolated to scattered
showers to develop with the heating of the day, but this all should
be just north of the forecast area.  Otherwise, clear skies are
expected for much of the area with additonal clouds in northeast MO
and west-central IL.  Westerly flow will support deep mixing,
resulting in max temps from the 60s in northern MO and central IL to
the 70s elsewhere.

TES

.LONG TERM...  (Tonight through Wednesday)
Issued at 333 AM CDT Thu Apr 28 2016

A weak sfc ridge builds into the area tonight, keeping the area dry
and cooler thru Fri morning.

The leading s/w may spread precip into the region as early as Fri
afternoon. Mdl differences continue with this system, but have
trended twd the slightly faster/more nrly ECMWF/NAM/local WRF solns.
This system will keep precip in the area thru much of the weekend,
tho Fri night thru Sat night still appears to be the bulk of the
precip. Given the mdl differences, uncertainty remains, but can not
rule out a severe threat on Sat. This threat will largely depend
upon where the sfc fnt sets up and if precip from overnight Fri can
move out of the area early enough for recovery.

Next week and beyond, sfc ridge builds into the area, keeping the
remainder of the forecast period largely dry. A secondary cdfnt
pushes thru the area sometime Wed. Mdls suggest this fnt will have
enuf moisture to generate precip, tho timing differences remain.
With Gulf cut off, do not believe enuf moisture will exist for
precip, but have kept low PoPs in for now.

Tilly

&&

.AVIATION...  (For the 12z TAFs through 12z Friday Morning)
Issued at 645 AM CDT Thu Apr 28 2016

Outside patchy fog around UIN which should be dissipating very
soon, VFR conditions and dry wx are expected to prevail at the
TAF sites thru the valid period. A region of MVFR CIGs over in
northwest MO will edge COU and UIN later this morning but are
expected to be around 3500ft when they do. Some isolated SHRA are
possible this afternoon just north of UIN, but should be enough to
the north to preclude mention in the UIN TAF. Otherwise, W winds
will veer NW by this evening and then become light and variable
late tonight and Friday morning.

TES

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 280834
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
334 AM CDT THU APR 28 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 333 AM CDT Thu Apr 28 2016

A stacked storm system was centered over western IA early this
morning.  At the surface, an occluded front extends southeast from
this storm center to a triple point in southwest IL, where a cold
front extends further south from there and a warm front extends east
from the triple point.  Temperatures were in the 60s ahead of the
cold front in southern IL, and have fallen into the 50s elsewhere.
Skies had also cleared over most areas, but some wraparound clouds
have recently moved back into sections of northwest MO.  A small
area of dense fog has developed just north of the front and triple
point, but the favorability to sustain this fog should decrease
heading towards dawn as the fronts move thru and the triple point
pulls away.

The surface triple point is expected to move out of the forecast
area into east-central IL by 12z this morning, taking the other
fronts out of the forecast area as well, leaving westerly flow in
its wake, and a surface TROF just to our north in southern IA and
central IL.  During this time, the storm center will track from
western IA into northeast IA with an upper level disturbance
will rotate thru southern IA by this afternoon.

The combination of some weak upper support and a surface boundary
and residual moisture should be enough for isolated to scattered
showers to develop with the heating of the day, but this all should
be just north of the forecast area.  Otherwise, clear skies are
expected for much of the area with additonal clouds in northeast MO
and west-central IL.  Westerly flow will support deep mixing,
resulting in max temps from the 60s in northern MO and central IL to
the 70s elsewhere.

TES

.LONG TERM...  (Tonight through Wednesday)
Issued at 333 AM CDT Thu Apr 28 2016

A weak sfc ridge builds into the area tonight, keeping the area dry
and cooler thru Fri morning.

The leading s/w may spread precip into the region as early as Fri
afternoon. Mdl differences continue with this system, but have
trended twd the slightly faster/more nrly ECMWF/NAM/local WRF solns.
This system will keep precip in the area thru much of the weekend,
tho Fri night thru Sat night still appears to be the bulk of the
precip. Given the mdl differences, uncertainty remains, but can not
rule out a severe threat on Sat. This threat will largely depend
upon where the sfc fnt sets up and if precip from overnight Fri can
move out of the area early enough for recovery.

Next week and beyond, sfc ridge builds into the area, keeping the
remainder of the forecast period largely dry. A secondary cdfnt
pushes thru the area sometime Wed. Mdls suggest this fnt will have
enuf moisture to generate precip, tho timing differences remain.
With Gulf cut off, do not believe enuf moisture will exist for
precip, but have kept low PoPs in for now.


Tilly

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1213 AM CDT Thu Apr 28 2016

Thunderstorms are clearing the area to the east at this time. Any
storms will be capable of producing gusty wind, hail and IFR
conditions in heavy rain. To the west of the storms, expect VFR
flight conditions to prevail across most of the area for the rest
of the night. There is some fog developing over northeast
Missouri...which could spread into west central Illinois...however
am not very confident in how low to go. Regardless, fog threat
should be done by 12-13Z as drier air moves into the area. Some
MVFR ceilings likely across northeast MO and west central IL
Thursday as well...though some guidance has the clouds above 3,000
ft.

Specifics for KSTL:

VFR flight conditions are expected at Lambert through Thursday.

Carney

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     74  50  70  56 /   0   5  10  70
Quincy          64  44  66  51 /  10   5  10  60
Columbia        70  47  68  56 /   0   5  40  80
Jefferson City  73  49  70  57 /   0   5  40  80
Salem           74  50  70  56 /   0   5  10  60
Farmington      77  50  72  56 /   0   5  30  70

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 280528
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1228 AM CDT THU APR 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Wed Apr 27 2016

The air mass has recovered in the wake of the morning storms. The
combination of increasing moisture and heating along with
overspreading steeper mid level lapse rates has produced SBCAPE
from 1500-2000+ j/kg south of the warm front. The warm front was
draped from the surface low in southeast NE through northeast MO
and into south central IL. Satellite imagery shows a rather
extensive cu field and right now we sit and wait. A couple of
scenarios are possible from the current obs and CAMs. One is that
soley the broken line of storms in northeast KS/northwest MO will
continue to develop southward some and thing swing northeast
across portions of northern MO as the short wave trof located
across eastern KS rotates northeast this evening. Another scenario
is a combination of the aforementioned evolution, and additionally
scattered more discrete storms will form from central thru
northeast MO between 21-23z as large scale ascent associated with
the short wave overspreads the area. Primary zone will again be
the north of I-70 with more isolated development further south.
Threats are primarily large hail and some tornado potential across
northeast MO where surface winds are locally backed enhancing the
low level shear. Believe all of the activity should have exited
the area by 06-07z as the upper low/trof lifts northeast and the
surface cold front advances across the area.

Glass

.LONG TERM...  (Thursday through Next Wednesday)
Issued at 332 PM CDT Wed Apr 27 2016

Deep westerly flow in the wake of the front will result in good
drying and tranquil weather Thursday with weak high pressure
dominating Thursday night.

Things begin to get busy again Friday into the weekend, and especially
Friday night into Saturday night. There are model differences with
the position and speed of the upper low/trof and associated surface
system. At this time the GFS looks too far south and have more
closely followed the ECMWF and NAM.

The approach of the next deep upstream upper trof and retreating
high pressure will allow for an initial short wave to impact the
area as early as late Friday afternoon at which time low level
moisture return will begin to get underway. I have some low pops
from central into southeast MO. This scenario is most likely to
really get underway on Friday night with widespread showers and
thunderstorms in response to the southerly LLJ and large scale
ascent with the short wave. The thunderstorm threat will remain
high Saturday into Saturday night with the advancing upper trof
and attendant cold front moving across the region. A broad,
unstable and significantly sheared warm sector in advance of the
front would suggest severe weather potential as well.

Glass

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1213 AM CDT Thu Apr 28 2016

Thunderstorms are clearing the area to the east at this time. Any
storms will be capable of producing gusty wind, hail and IFR
conditions in heavy rain. To the west of the storms, expect VFR
flight conditions to prevail across most of the area for the rest
of the night. There is some fog developing over northeast
Missouri...which could spread into west central Illinois...however
am not very confident in how low to go. Regardless, fog threat
should be done by 12-13Z as drier air moves into the area. Some
MVFR ceilings likely across northeast MO and west central IL
Thursday as well...though some guidance has the clouds above 3,000
ft.

Specifics for KSTL:

VFR flight conditions are expected at Lambert through Thursday.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 280528
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1228 AM CDT THU APR 28 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Wed Apr 27 2016

The air mass has recovered in the wake of the morning storms. The
combination of increasing moisture and heating along with
overspreading steeper mid level lapse rates has produced SBCAPE
from 1500-2000+ j/kg south of the warm front. The warm front was
draped from the surface low in southeast NE through northeast MO
and into south central IL. Satellite imagery shows a rather
extensive cu field and right now we sit and wait. A couple of
scenarios are possible from the current obs and CAMs. One is that
soley the broken line of storms in northeast KS/northwest MO will
continue to develop southward some and thing swing northeast
across portions of northern MO as the short wave trof located
across eastern KS rotates northeast this evening. Another scenario
is a combination of the aforementioned evolution, and additionally
scattered more discrete storms will form from central thru
northeast MO between 21-23z as large scale ascent associated with
the short wave overspreads the area. Primary zone will again be
the north of I-70 with more isolated development further south.
Threats are primarily large hail and some tornado potential across
northeast MO where surface winds are locally backed enhancing the
low level shear. Believe all of the activity should have exited
the area by 06-07z as the upper low/trof lifts northeast and the
surface cold front advances across the area.

Glass

.LONG TERM...  (Thursday through Next Wednesday)
Issued at 332 PM CDT Wed Apr 27 2016

Deep westerly flow in the wake of the front will result in good
drying and tranquil weather Thursday with weak high pressure
dominating Thursday night.

Things begin to get busy again Friday into the weekend, and especially
Friday night into Saturday night. There are model differences with
the position and speed of the upper low/trof and associated surface
system. At this time the GFS looks too far south and have more
closely followed the ECMWF and NAM.

The approach of the next deep upstream upper trof and retreating
high pressure will allow for an initial short wave to impact the
area as early as late Friday afternoon at which time low level
moisture return will begin to get underway. I have some low pops
from central into southeast MO. This scenario is most likely to
really get underway on Friday night with widespread showers and
thunderstorms in response to the southerly LLJ and large scale
ascent with the short wave. The thunderstorm threat will remain
high Saturday into Saturday night with the advancing upper trof
and attendant cold front moving across the region. A broad,
unstable and significantly sheared warm sector in advance of the
front would suggest severe weather potential as well.

Glass

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1213 AM CDT Thu Apr 28 2016

Thunderstorms are clearing the area to the east at this time. Any
storms will be capable of producing gusty wind, hail and IFR
conditions in heavy rain. To the west of the storms, expect VFR
flight conditions to prevail across most of the area for the rest
of the night. There is some fog developing over northeast
Missouri...which could spread into west central Illinois...however
am not very confident in how low to go. Regardless, fog threat
should be done by 12-13Z as drier air moves into the area. Some
MVFR ceilings likely across northeast MO and west central IL
Thursday as well...though some guidance has the clouds above 3,000
ft.

Specifics for KSTL:

VFR flight conditions are expected at Lambert through Thursday.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 272354
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
654 PM CDT WED APR 27 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Wed Apr 27 2016

The air mass has recovered in the wake of the morning storms. The
combination of increasing moisture and heating along with
overspreading steeper mid level lapse rates has produced SBCAPE
from 1500-2000+ j/kg south of the warm front. The warm front was
draped from the surface low in southeast NE through northeast MO
and into south central IL. Satellite imagery shows a rather
extensive cu field and right now we sit and wait. A couple of
scenarios are possible from the current obs and CAMs. One is that
soley the broken line of storms in northeast KS/northwest MO will
continue to develop southward some and thing swing northeast
across portions of northern MO as the short wave trof located
across eastern KS rotates northeast this evening. Another scenario
is a combination of the aforementioned evolution, and additionally
scattered more discrete storms will form from central thru
northeast MO between 21-23z as large scale ascent associated with
the short wave overspreads the area. Primary zone will again be
the north of I-70 with more isolated development further south.
Threats are primarily large hail and some tornado potential across
northeast MO where surface winds are locally backed enhancing the
low level shear. Believe all of the activity should have exited
the area by 06-07z as the upper low/trof lifts northeast and the
surface cold front advances across the area.

Glass

.LONG TERM...  (Thursday through Next Wednesday)
Issued at 332 PM CDT Wed Apr 27 2016

Deep westerly flow in the wake of the front will result in good
drying and tranquil weather Thursday with weak high pressure
dominating Thursday night.

Things begin to get busy again Friday into the weekend, and especially
Friday night into Saturday night. There are model differences with
the position and speed of the upper low/trof and associated surface
system. At this time the GFS looks too far south and have more
closely followed the ECMWF and NAM.

The approach of the next deep upstream upper trof and retreating
high pressure will allow for an initial short wave to impact the
area as early as late Friday afternoon at which time low level
moisture return will begin to get underway. I have some low pops
from central into southeast MO. This scenario is most likely to
really get underway on Friday night with widespread showers and
thunderstorms in response to the southerly LLJ and large scale
ascent with the short wave. The thunderstorm threat will remain
high Saturday into Saturday night with the advancing upper trof
and attendant cold front moving across the region. A broad,
unstable and significantly sheared warm sector in advance of the
front would suggest severe weather potential as well.

Glass

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 652 PM CDT Wed Apr 27 2016

Warm front currently lies across northeast Missouri into west
central and south central Illinois. A line of thunderstorms, some
severe, are moving across central Missouri. This line will likely
affect KUIN and possibly KCOU through 04Z. Thunderstorms may
develop ahead of this line at the St. Louis area terminals, or may
occur with this line around 04-05Z. Conditions with the storms
will include MVFR or possible IFR ceilings and visibilities as
well as hail and wind gusts over 50kts. Dry and VFR conditions are
expected after 06Z.

Specifics for KSTL: Scattered thunderstorms will continue to
develop ahead of a line that will move across the terminal around
04Z. Conditions with the storms will include MVFR or possible IFR
ceilings and visibilities as well as hail and strong wind gusts.
Dry and VFR conditions are expected once the storms pass.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 272354
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
654 PM CDT WED APR 27 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Wed Apr 27 2016

The air mass has recovered in the wake of the morning storms. The
combination of increasing moisture and heating along with
overspreading steeper mid level lapse rates has produced SBCAPE
from 1500-2000+ j/kg south of the warm front. The warm front was
draped from the surface low in southeast NE through northeast MO
and into south central IL. Satellite imagery shows a rather
extensive cu field and right now we sit and wait. A couple of
scenarios are possible from the current obs and CAMs. One is that
soley the broken line of storms in northeast KS/northwest MO will
continue to develop southward some and thing swing northeast
across portions of northern MO as the short wave trof located
across eastern KS rotates northeast this evening. Another scenario
is a combination of the aforementioned evolution, and additionally
scattered more discrete storms will form from central thru
northeast MO between 21-23z as large scale ascent associated with
the short wave overspreads the area. Primary zone will again be
the north of I-70 with more isolated development further south.
Threats are primarily large hail and some tornado potential across
northeast MO where surface winds are locally backed enhancing the
low level shear. Believe all of the activity should have exited
the area by 06-07z as the upper low/trof lifts northeast and the
surface cold front advances across the area.

Glass

.LONG TERM...  (Thursday through Next Wednesday)
Issued at 332 PM CDT Wed Apr 27 2016

Deep westerly flow in the wake of the front will result in good
drying and tranquil weather Thursday with weak high pressure
dominating Thursday night.

Things begin to get busy again Friday into the weekend, and especially
Friday night into Saturday night. There are model differences with
the position and speed of the upper low/trof and associated surface
system. At this time the GFS looks too far south and have more
closely followed the ECMWF and NAM.

The approach of the next deep upstream upper trof and retreating
high pressure will allow for an initial short wave to impact the
area as early as late Friday afternoon at which time low level
moisture return will begin to get underway. I have some low pops
from central into southeast MO. This scenario is most likely to
really get underway on Friday night with widespread showers and
thunderstorms in response to the southerly LLJ and large scale
ascent with the short wave. The thunderstorm threat will remain
high Saturday into Saturday night with the advancing upper trof
and attendant cold front moving across the region. A broad,
unstable and significantly sheared warm sector in advance of the
front would suggest severe weather potential as well.

Glass

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 652 PM CDT Wed Apr 27 2016

Warm front currently lies across northeast Missouri into west
central and south central Illinois. A line of thunderstorms, some
severe, are moving across central Missouri. This line will likely
affect KUIN and possibly KCOU through 04Z. Thunderstorms may
develop ahead of this line at the St. Louis area terminals, or may
occur with this line around 04-05Z. Conditions with the storms
will include MVFR or possible IFR ceilings and visibilities as
well as hail and wind gusts over 50kts. Dry and VFR conditions are
expected after 06Z.

Specifics for KSTL: Scattered thunderstorms will continue to
develop ahead of a line that will move across the terminal around
04Z. Conditions with the storms will include MVFR or possible IFR
ceilings and visibilities as well as hail and strong wind gusts.
Dry and VFR conditions are expected once the storms pass.

Britt

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 272059
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
359 PM CDT WED APR 27 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Wed Apr 27 2016

The air mass has recovered in the wake of the morning storms. The
combination of increasing moisture and heating along with
overspreading steeper mid level lapse rates has produced SBCAPE
from 1500-2000+ j/kg south of the warm front. The warm front was
drapped from the surface low in southeast NE through northeast MO
and into south central IL. Satellite imagery shows a rather
extensive cu field and right now we sit and wait. A couple of
scenarios are possible from the current obs and CAMs. One is that
soley the broken line of storms in northeast KS/northwest MO will
continue to develop southward some and thing swing northeast
across portions of northern MO as the short wave trof located
across eastern KS rotates northeast this evening. Another scenario
is a combination of the aforementioned evolution, and additionally
scattered more discrete storms will form from central thru
northeast MO between 21-23z as large scale ascent associated with
the short wave overspreads the area. Primary zone will again be
the north of I-70 with more isolated development further south.
Threats are primarily large hail and some tornado potential across
northeast MO where surface winds are locally backed enhancing the
low level shear. Believe all of the activity should have exited
the area by 06-07z as the upper low/trof lifts northeast and the
surface cold front advances across the area.

Glass

.LONG TERM...  (Thursday through Next Wednesday)
Issued at 332 PM CDT Wed Apr 27 2016

Deep westerly flow in the wake of the front will result in good
drying and tranquil weather Thursday with weak high pressure
dominating Thursday night.

Things begin to get busy again Friday into the weekend, and especially
Friday night into Saturday night. There are model differences with
the position and speed of the upper low/trof and associated surface
system. At this time the GFS looks too far south and have more
closely followed the ECMWF and NAM.

The approach of the next deep upstream upper trof and retreating
high pressure will allow for an initial short wave to impact the
area as early as late Friday afternoon at which time low level
moisture return will begin to get underway. I have some low pops
from central into southeast MO. This scenario is most likely to
really get underway on Friday night with widespread showers and
thunderstorms in response to the southerly LLJ and large scale
ascent with the short wave. The thunderstorm threat will remain
high Saturday into Saturday night with the advancing upper trof
and attendant cold front moving across the region. A broad,
unstable and significantly sheared warm sector in advance of the
front would suggest severe weather potential as well.

Glass

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1235 PM CDT Wed Apr 27 2016

North-south oriented isolated-scattered showers and weak
thunderstorms is expected to move east of KUIN and metro terminals
by 1900 UTC. Another round of at least scattered thunderstorms is
expected to develop by late afternoon. Development may be east of
KCOU but is expected to be west of the metro terminals as well as
KUIN. Atmosphere should destabilize enough to cause some storms to
be strong/severe with large hail and damaging winds possible with
stronger thunderstorms in addition to heavy rain/IFR visbys. By
mid- late evening...thunderstorms are expected to move off to the
east of the terminals with VFR conditions expected into Thursday
afternoon. Only exception could be at KUIN as some high-end MVFR
ceilings are possible by mid morning on Thursday. Winds will
initially be southeast early this afternoon before turning out of
the west/southwest behind the frontal passage later on tonight.


Specifics for KSTL:

Isolated-scattered showers/weak storms expected to quickly move
to the east of the terminal early this afternoon. Partially
clearing sky to the west will advect in within the next 1-2 hours
and help destabilize the atmosphere. Scattered thunderstorms are
expected to develop to the west of the terminal by mid afternoon
with storms possibly affecting the terminal between late afternoon
and early evening. Stronger thunderstorms will be capable of
producing large hail and damaging winds as well as heavy rain/IFR
visbys. Threat of storms should exit by mid-late evening...with
VFR conditions in its wake. Winds will turn from the southeast
early this afternoon to the west/southwest behind a frontal
boundary late tonight/early Thursday morning.

Gosselin

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 271745
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1245 PM CDT WED APR 27 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 339 AM CDT Wed Apr 27 2016

A strong upper level storm system was centered over western KS early
this morning with a RIDGE axis over our region.  The surface
reflection was located over central KS, showing that it had not yet
become occluded, with a frontal boundary that has become nearly
stationary stretching eastward to near the I-70 corridor in MO and
IL.  Temps were in the 50s and low 60s across our region with what
was a band of severe TSRA but has since weakened moving towards our
region from western MO.

The storm system center is expected to track northeast to the mid-MO
river valley by late this afternoon, and with the RIDGE axis over
our way slow to yield ground, will result in the TROF associated
with the storm itself to become increasingly negatively-tilted, with
the TROF axis anticipated to be over our region during the afternoon
hours.  At the surface, the low center will become occluded by
this afternoon with a new triple point likely just NW of STL metro,
with the old east-west quasistationary boundary extending east from
this, and a cold front extending south from the new triple point.

With all of this in mind, it appears the leading more active
convective edge currently from central to south-central MO will
become increasingly detached from the enhanced stratiform pcpn
behind it early this morning as it gradually dissipates, but
the leading edge convective elements should still sweep thru much
of the forecast area in the process accompanied by gusts of 30-
40mph.  This round is expected to exit into eastern IL by late
morning.

A brief period of quiet wx for midday looks likely before the
approach of the upper TROF and increasing instability should set
off numerous TSRA by mid-afternoon areawide.  The synoptic setup
will be such that if things can de-stabilize enough for the
afternoon, there will be a tornado threat, namely near and just
northeast of the quasi-stationary east-west frontal boundary that
will probably be just north of STL by this time.  Otherwise, the
environmental shear will be sufficient for storms capable of large
hail and damaging winds, notably along the edge of the approaching
dry slot from the west.  Maintained likely and categorical PoPs for
this afternoon.

Temps are going to be tricky again, with a lot of conditions being
set on pcpn development and cloud cover, so stayed within the
boundaries of MOS, with 60s north of the front and 70s elsewhere.

TES

.LONG TERM...  (Tonight through Tuesday)
Issued at 339 AM CDT Wed Apr 27 2016

Focus for the short term will be convection and severe potential.

Forecast for tonight is conditional on how storms today unfold.
Believe there will be two main areas of storms at the beginning of
the period. One area shud be across ern portions of the CWA where
storms developing this afternoon near the triple point move ewd.
These shud exit the area mid to late evening. The second area of
convection is expected across nrn portions of the CWA under the
better upper level support. What severe threat develops this
afternoon, will linger into the evening, but out of the region by
Midnight.

Mdls are in fairly good agreement over the remainder of the short
term. The upper low lifts nwd on Thurs, leaving zonal flow over the
region. Can not rule out precip across far nrn portions of the CWA,
but believe the bulk of the precip will remain N of the fnt on
Thurs. With the sfc ridge building into the region, the remainder of
the week, and thru the weekend, is expected to be seasonably cool.
There is still some question of temps for Thurs as the 850mb fnt is
progd to be across srn MO/IL. The going forecast may still be too
warm, however, with deeper mixing expected and some uncertainty,
believe trend is in the right direction.

Looking into the extd, the deep trof over the Rockies is still
expected to eject into the Plains on Fri, with precip spreading into
the area Fri night and continuing thru much of the weekend. The
system this weekend has similarities to the current system impacting
the area. There is differences among guidance and any severe threat
will be conditional on location of sfc features and therefore a low
probability attm.

With a sfc ridge building into the area Mon and thru the remainder
of the forecast period, chances for precip are small. Temps are
expected to be aob seasonal average thru mid-week.

Tilly

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1235 PM CDT Wed Apr 27 2016

North-south oriented isolated-scattered showers and weak
thunderstorms is expected to move east of KUIN and metro terminals
by 1900 UTC. Another round of at least scattered thunderstorms is
expected to develop by late afternoon. Development may be east of
KCOU but is expected to be west of the metro terminals as well as
KUIN. Atmosphere should destabilize enough to cause some storms to
be strong/severe with large hail and damaging winds possible with
stronger thunderstorms in addition to heavy rain/IFR visbys. By
mid- late evening...thunderstorms are expected to move off to the
east of the terminals with VFR conditions expected into Thursday
afternoon. Only exception could be at KUIN as some high-end MVFR
ceilings are possible by mid morning on Thursday. Winds will
initially be southeast early this afternoon before turning out of
the west/southwest behind the frontal passage later on tonight.


Specifics for KSTL:

Isolated-scattered showers/weak storms expected to quickly move
to the east of the terminal early this afternoon. Partially
clearing sky to the west will advect in within the next 1-2 hours
and help destabilize the atmosphere. Scattered thunderstorms are
expected to develop to the west of the terminal by mid afternoon
with storms possibly affecting the terminal between late afternoon
and early evening. Stronger thunderstorms will be capable of
producing large hail and damaging winds as well as heavy rain/IFR
visbys. Threat of storms should exit by mid-late evening...with
VFR conditions in its wake. Winds will turn from the southeast
early this afternoon to the west/southwest behind a frontal
boundary late tonight/early Thursday morning.

Gosselin

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 271745
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1245 PM CDT WED APR 27 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 339 AM CDT Wed Apr 27 2016

A strong upper level storm system was centered over western KS early
this morning with a RIDGE axis over our region.  The surface
reflection was located over central KS, showing that it had not yet
become occluded, with a frontal boundary that has become nearly
stationary stretching eastward to near the I-70 corridor in MO and
IL.  Temps were in the 50s and low 60s across our region with what
was a band of severe TSRA but has since weakened moving towards our
region from western MO.

The storm system center is expected to track northeast to the mid-MO
river valley by late this afternoon, and with the RIDGE axis over
our way slow to yield ground, will result in the TROF associated
with the storm itself to become increasingly negatively-tilted, with
the TROF axis anticipated to be over our region during the afternoon
hours.  At the surface, the low center will become occluded by
this afternoon with a new triple point likely just NW of STL metro,
with the old east-west quasistationary boundary extending east from
this, and a cold front extending south from the new triple point.

With all of this in mind, it appears the leading more active
convective edge currently from central to south-central MO will
become increasingly detached from the enhanced stratiform pcpn
behind it early this morning as it gradually dissipates, but
the leading edge convective elements should still sweep thru much
of the forecast area in the process accompanied by gusts of 30-
40mph.  This round is expected to exit into eastern IL by late
morning.

A brief period of quiet wx for midday looks likely before the
approach of the upper TROF and increasing instability should set
off numerous TSRA by mid-afternoon areawide.  The synoptic setup
will be such that if things can de-stabilize enough for the
afternoon, there will be a tornado threat, namely near and just
northeast of the quasi-stationary east-west frontal boundary that
will probably be just north of STL by this time.  Otherwise, the
environmental shear will be sufficient for storms capable of large
hail and damaging winds, notably along the edge of the approaching
dry slot from the west.  Maintained likely and categorical PoPs for
this afternoon.

Temps are going to be tricky again, with a lot of conditions being
set on pcpn development and cloud cover, so stayed within the
boundaries of MOS, with 60s north of the front and 70s elsewhere.

TES

.LONG TERM...  (Tonight through Tuesday)
Issued at 339 AM CDT Wed Apr 27 2016

Focus for the short term will be convection and severe potential.

Forecast for tonight is conditional on how storms today unfold.
Believe there will be two main areas of storms at the beginning of
the period. One area shud be across ern portions of the CWA where
storms developing this afternoon near the triple point move ewd.
These shud exit the area mid to late evening. The second area of
convection is expected across nrn portions of the CWA under the
better upper level support. What severe threat develops this
afternoon, will linger into the evening, but out of the region by
Midnight.

Mdls are in fairly good agreement over the remainder of the short
term. The upper low lifts nwd on Thurs, leaving zonal flow over the
region. Can not rule out precip across far nrn portions of the CWA,
but believe the bulk of the precip will remain N of the fnt on
Thurs. With the sfc ridge building into the region, the remainder of
the week, and thru the weekend, is expected to be seasonably cool.
There is still some question of temps for Thurs as the 850mb fnt is
progd to be across srn MO/IL. The going forecast may still be too
warm, however, with deeper mixing expected and some uncertainty,
believe trend is in the right direction.

Looking into the extd, the deep trof over the Rockies is still
expected to eject into the Plains on Fri, with precip spreading into
the area Fri night and continuing thru much of the weekend. The
system this weekend has similarities to the current system impacting
the area. There is differences among guidance and any severe threat
will be conditional on location of sfc features and therefore a low
probability attm.

With a sfc ridge building into the area Mon and thru the remainder
of the forecast period, chances for precip are small. Temps are
expected to be aob seasonal average thru mid-week.

Tilly

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1235 PM CDT Wed Apr 27 2016

North-south oriented isolated-scattered showers and weak
thunderstorms is expected to move east of KUIN and metro terminals
by 1900 UTC. Another round of at least scattered thunderstorms is
expected to develop by late afternoon. Development may be east of
KCOU but is expected to be west of the metro terminals as well as
KUIN. Atmosphere should destabilize enough to cause some storms to
be strong/severe with large hail and damaging winds possible with
stronger thunderstorms in addition to heavy rain/IFR visbys. By
mid- late evening...thunderstorms are expected to move off to the
east of the terminals with VFR conditions expected into Thursday
afternoon. Only exception could be at KUIN as some high-end MVFR
ceilings are possible by mid morning on Thursday. Winds will
initially be southeast early this afternoon before turning out of
the west/southwest behind the frontal passage later on tonight.


Specifics for KSTL:

Isolated-scattered showers/weak storms expected to quickly move
to the east of the terminal early this afternoon. Partially
clearing sky to the west will advect in within the next 1-2 hours
and help destabilize the atmosphere. Scattered thunderstorms are
expected to develop to the west of the terminal by mid afternoon
with storms possibly affecting the terminal between late afternoon
and early evening. Stronger thunderstorms will be capable of
producing large hail and damaging winds as well as heavy rain/IFR
visbys. Threat of storms should exit by mid-late evening...with
VFR conditions in its wake. Winds will turn from the southeast
early this afternoon to the west/southwest behind a frontal
boundary late tonight/early Thursday morning.

Gosselin

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 271155
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
655 AM CDT WED APR 27 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 339 AM CDT Wed Apr 27 2016

A strong upper level storm system was centered over western KS early
this morning with a RIDGE axis over our region.  The surface
reflection was located over central KS, showing that it had not yet
become occluded, with a frontal boundary that has become nearly
stationary stretching eastward to near the I-70 corridor in MO and
IL.  Temps were in the 50s and low 60s across our region with what
was a band of severe TSRA but has since weakened moving towards our
region from western MO.

The storm system center is expected to track northeast to the mid-MO
river valley by late this afternoon, and with the RIDGE axis over
our way slow to yield ground, will result in the TROF associated
with the storm itself to become increasingly negatively-tilted, with
the TROF axis anticipated to be over our region during the afternoon
hours.  At the surface, the low center will become occluded by
this afternoon with a new triple point likely just NW of STL metro,
with the old east-west quasistationary boundary extending east from
this, and a cold front extending south from the new triple point.

With all of this in mind, it appears the leading more active
convective edge currently from central to south-central MO will
become increasingly detached from the enhanced stratiform pcpn
behind it early this morning as it gradually dissipates, but
the leading edge convective elements should still sweep thru much
of the forecast area in the process accompanied by gusts of 30-
40mph.  This round is expected to exit into eastern IL by late
morning.

A brief period of quiet wx for midday looks likely before the
approach of the upper TROF and increasing instability should set
off numerous TSRA by mid-afternoon areawide.  The synoptic setup
will be such that if things can de-stabilize enough for the
afternoon, there will be a tornado threat, namely near and just
northeast of the quasi-stationary east-west frontal boundary that
will probably be just north of STL by this time.  Otherwise, the
environmental shear will be sufficient for storms capable of large
hail and damaging winds, notably along the edge of the approaching
dry slot from the west.  Maintained likely and categorical PoPs for
this afternoon.

Temps are going to be tricky again, with a lot of conditions being
set on pcpn development and cloud cover, so stayed within the
boundaries of MOS, with 60s north of the front and 70s elsewhere.

TES

.LONG TERM...  (Tonight through Tuesday)
Issued at 339 AM CDT Wed Apr 27 2016

Focus for the short term will be convection and severe potential.

Forecast for tonight is conditional on how storms today unfold.
Believe there will be two main areas of storms at the beginning of
the period. One area shud be across ern portions of the CWA where
storms developing this afternoon near the triple point move ewd.
These shud exit the area mid to late evening. The second area of
convection is expected across nrn portions of the CWA under the
better upper level support. What severe threat develops this
afternoon, will linger into the evening, but out of the region by
Midnight.

Mdls are in fairly good agreement over the remainder of the short
term. The upper low lifts nwd on Thurs, leaving zonal flow over the
region. Can not rule out precip across far nrn portions of the CWA,
but believe the bulk of the precip will remain N of the fnt on
Thurs. With the sfc ridge building into the region, the remainder of
the week, and thru the weekend, is expected to be seasonably cool.
There is still some question of temps for Thurs as the 850mb fnt is
progd to be across srn MO/IL. The going forecast may still be too
warm, however, with deeper mixing expected and some uncertainty,
believe trend is in the right direction.

Looking into the extd, the deep trof over the Rockies is still
expected to eject into the Plains on Fri, with precip spreading into
the area Fri night and continuing thru much of the weekend. The
system this weekend has similarities to the current system impacting
the area. There is differences among guidance and any severe threat
will be conditional on location of sfc features and therefore a low
probability attm.

With a sfc ridge building into the area Mon and thru the remainder
of the forecast period, chances for precip are small. Temps are
expected to be aob seasonal average thru mid-week.

Tilly

&&

.AVIATION...  (For the 12z TAFs through 12z Thursday Morning)
Issued at 645 AM CDT Wed Apr 27 2016

Rain will weaken or exit this morning as IFR CIGs slowly retreat
to the north. They should be exiting all STL metro sites in the
next hour or two, but may take much if not all of the morning
before lifting at UIN. Another round of storms will fire this
afternoon and handled with VCTS at most sites with targeting a
smaller range of time in the TAF with TEMPO groups until
confidence increases to slide to prevailing. Rain chances will
sharply decrease this evening and skies clear.

TES

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 270840
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
340 AM CDT WED APR 27 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 339 AM CDT Wed Apr 27 2016

A strong upper level storm system was centered over western KS early
this morning with a RIDGE axis over our region.  The surface
reflection was located over central KS, showing that it had not yet
become occluded, with a frontal boundary that has become nearly
stationary stretching eastward to near the I-70 corridor in MO and
IL.  Temps were in the 50s and low 60s across our region with what
was a band of severe TSRA but has since weakened moving towards our
region from western MO.

The storm system center is expected to track northeast to the mid-MO
river valley by late this afternoon, and with the RIDGE axis over
our way slow to yield ground, will result in the TROF associated
with the storm itself to become increasingly negatively-tilted, with
the TROF axis anticipated to be over our region during the afternoon
hours.  At the surface, the low center will become occluded by
this afternoon with a new triple point likely just NW of STL metro,
with the old east-west quasistationary boundary extending east from
this, and a cold front extending south from the new triple point.

With all of this in mind, it appears the leading more active
convective edge currently from central to south-central MO will
become increasingly detached from the enhanced stratiform pcpn
behind it early this morning as it gradually dissipates, but
the leading edge convective elements should still sweep thru much
of the forecast area in the process accompanied by gusts of 30-
40mph.  This round is expected to exit into eastern IL by late
morning.

A brief period of quiet wx for midday looks likely before the
approach of the upper TROF and increasing instability should set
off numerous TSRA by mid-afternoon areawide.  The synoptic setup
will be such that if things can de-stabilize enough for the
afternoon, there will be a tornado threat, namely near and just
northeast of the quasi-stationary east-west frontal boundary that
will probably be just north of STL by this time.  Otherwise, the
environmental shear will be sufficient for storms capable of large
hail and damaging winds, notably along the edge of the approaching
dry slot from the west.  Maintained likely and categorical PoPs for
this afternoon.

Temps are going to be tricky again, with a lot of conditions being
set on pcpn development and cloud cover, so stayed within the
boundaries of MOS, with 60s north of the front and 70s elsewhere.

TES

.LONG TERM...  (Tonight through Tuesday)
Issued at 339 AM CDT Wed Apr 27 2016

Focus for the short term will be convection and severe potential.

Forecast for tonight is conditional on how storms today unfold.
Believe there will be two main areas of storms at the beginning of
the period. One area shud be across ern portions of the CWA where
storms developing this afternoon near the triple point move ewd.
These shud exit the area mid to late evening. The second area of
convection is expected across nrn portions of the CWA under the
better upper level support. What severe threat develops this
afternoon, will linger into the evening, but out of the region by
Midnight.

Mdls are in fairly good agreement over the remainder of the short
term. The upper low lifts nwd on Thurs, leaving zonal flow over the
region. Can not rule out precip across far nrn portions of the CWA,
but believe the bulk of the precip will remain N of the fnt on
Thurs. With the sfc ridge building into the region, the remainder of
the week, and thru the weekend, is expected to be seasonably cool.
There is still some question of temps for Thurs as the 850mb fnt is
progd to be across srn MO/IL. The going forecast may still be too
warm, however, with deeper mixing expected and some uncertainty,
believe trend is in the right direction.

Looking into the extd, the deep trof over the Rockies is still
expected to eject into the Plains on Fri, with precip spreading into
the area Fri night and continuing thru much of the weekend. The
system this weekend has similarities to the current system impacting
the area. There is differences among guidance and any severe threat
will be conditional on location of sfc features and therefore a low
probability attm.

With a sfc ridge building into the area Mon and thru the remainder
of the forecast period, chances for precip are small. Temps are
expected to be aob seasonal average thru mid-week.

Tilly

&&

.AVIATION...  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1230 AM CDT Wed Apr 27 2016

Pockets of IFR are showing up here and there in observations
around the STL Metro area. Earlier guidance hinted at this and
subsequent runs continue to develop and expand IFR ceilings across
much of the area before daybreak. More confidence in this now
since it`s actually developing. Otherwise, expect waves of showers
and thunderstorms across the area over the next 24 hours...likely
ending early to mid Wednesday evening. Any thunderstorm will be
capable of lowering flight conditions to IFR. Hail and gusty winds will also be a continuing
threat.

Specifics for KSTL:

Looks like Lambert will be in and out of IFR ceilings for a few
hours and likely prevailing IFR by 09-11Z. The first wave of
showers and thunderstorms should be moving into the vicinity of
the terminal by 10Z. And then another wave of storms is likely
after 18Z Wednesday.  Strength of the storms is uncertain at this
time, but any storm could produce brief periods of IFR conditions
in heavy rain. Hail and gusty winds will also be a continuing
threat.


Carney

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     76  57  76  50 /  80  70  10  10
Quincy          67  52  69  45 /  80  70  20  10
Columbia        74  51  72  47 /  60  40  10  10
Jefferson City  77  52  75  48 /  60  30  10  10
Salem           75  59  77  50 /  80  70  10  10
Farmington      75  55  79  50 /  70  30   5  10

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 270528
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1228 AM CDT WED APR 27 2016

.UPDATE...
Issued at 948 PM CDT Tue Apr 26 2016

Convection over eastern Kansas and northwest Missouri is
proceeding slowly eastward...about as expected. Looks like the
leading edges will be moving into the western fringes of our CWFA
by 06-07Z. Have made minor tweaks to the PoPs to slow the precip
accordingly. RAP is forecasting 1000-1500 J/Kg of MUCAPE along
with increasing deep layer shear...and this continues to point
toward the possibility of elevated severe storms with severe hail
being the primary threat.

Carney

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Tue Apr 26 2016

Current bowing convective system over SW IL has a well established
cold pool and will continue to move east into the western OH
Valley into a large region of unstable air in advance of it. The
deep convective line with any severe threat should clear the area by
500 pm with trailing stratiform rain clearing the CWA by early
evening. A prominent outflow boundary with the convective system,
which should have completely moved through the CWA by 00z, has
largely stabilized the air mass to boundary layer based storms in
its wake. I will retain some low chance pops this evening on the
fringes of our CWA however I think the vast majority of the
evening in the wake of the present system will be dry. Current
thinking is that overnight we will see a MCS that has evolved
across the Plains early this evening, move west to east into central
and finally eastern MO in the predawn hours. Additional showers
and thunderstorms could develop late this evening and overnight
ahead of the aforementioned progressive Plains MCS in response to
the LLJ and WAA along north of the retreating outflow boundary/warm
front composite. There will be a severe threat with this overnight
activity given MUCAPE of 1000+ j/kg and increasing southwesterly
deep layer shear, but not nearly as great as the system that moved
through today.

Glass

.LONG TERM...  (Wednesday through Next Tuesday)
Issued at 332 PM CDT Tue Apr 26 2016

A little unclear how everything will pan out on Wednesday. There
will likely be ongoing convection from a decaying MCS over parts
of eastern MO in the morning that will move into IL. However it
does appear that there will be sufficient air mass recovery in the
wake of the morning convection. How much and the most favored
corridors are hard to say. Mid level lapse rates will remain steep
and heating should lead to SBCAPE of at least 1500 j/kg over parts
of central MO by early afternoon. The combination of the east-northeast
rotating short wave trof and large scale ascent, and the attendant
advancing cold front should result in thunderstorm development
along/ahead of the cold front by mid afternoon. Coverage should
then increase through the remainder of the afternoon, with storms
persisting into the evening as the front and trof progress east.
We will probably see a mixed convective mode with all severe
weather threats. Most of the activity should have moved out of the
CWA by 06z Thursday.

The trof will be lifting to the northeast on Thursday with the
cold front advancing into the OH/TN Valley region. Present
indications are that increasingly deep westerly flow in the wake
of the front will lead to good drying and little if any
precipitation.

Next round of showers and thunderstorms looks to unfold Friday
night into the weekend. First with the LLJ, WAA, and a lead
impulse Friday night/Saturday and then with another formidable
upper trof and attendant cold front Saturday night into Sunday.

Glass

&&

.AVIATION...  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1230 AM CDT Wed Apr 27 2016

Pockets of IFR are showing up here and there in observations
around the STL Metro area. Earlier guidance hinted at this and
subsequent runs continue to develop and expand IFR ceilings across
much of the area before daybreak. More confidence in this now
since it`s actually developing. Otherwise, expect waves of showers
and thunderstorms across the area over the next 24 hours...likely
ending early to mid Wednesday evening. Any thunderstorm will be
capable of lowering flight conditions to IFR. Hail and gusty winds will also be a continuing
threat.

Specifics for KSTL:

Looks like Lambert will be in and out of IFR ceilings for a few
hours and likely prevailing IFR by 09-11Z. The first wave of
showers and thunderstorms should be moving into the vicinity of
the terminal by 10Z. And then another wave of storms is likely
after 18Z Wednesday.  Strength of the storms is uncertain at this
time, but any storm could produce brief periods of IFR conditions
in heavy rain. Hail and gusty winds will also be a continuing
threat.


Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 270322
AFDLSX

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
1022 PM CDT TUE APR 26 2016

.UPDATE...
Issued at 948 PM CDT Tue Apr 26 2016

Convection over eastern Kansas and northwest Missouri is
proceeding slowly eastward...about as expected. Looks like the
leading edges will be moving into the western fringes of our CWFA
by 06-07Z. Have made minor tweaks to the PoPs to slow the precip
accordingly. RAP is forecasting 1000-1500 J/Kg of MUCAPE along
with increasing deep layer shear...and this continues to point
toward the possibility of elevated severe storms with severe hail
being the primary threat.

Carney

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Tue Apr 26 2016

Current bowing convective system over SW IL has a well established
cold pool and will continue to move east into the western OH
Valley into a large region of unstable air in advance of it. The
deep convective line with any severe threat should clear the area by
500 pm with trailing stratiform rain clearing the CWA by early
evening. A prominent outflow boundary with the convective system,
which should have completely moved through the CWA by 00z, has
largely stabilized the air mass to boundary layer based storms in
its wake. I will retain some low chance pops this evening on the
fringes of our CWA however I think the vast majority of the
evening in the wake of the present system will be dry. Current
thinking is that overnight we will see a MCS that has evolved
across the Plains early this evening, move west to east into central
and finally eastern MO in the predawn hours. Additional showers
and thunderstorms could develop late this evening and overnight
ahead of the aforementioned progressive Plains MCS in response to
the LLJ and WAA along north of the retreating outflow boundary/warm
front composite. There will be a severe threat with this overnight
activity given MUCAPE of 1000+ j/kg and increasing southwesterly
deep layer shear, but not nearly as great as the system that moved
through today.

Glass

.LONG TERM...  (Wednesday through Next Tuesday)
Issued at 332 PM CDT Tue Apr 26 2016

A little unclear how everything will pan out on Wednesday. There
will likely be ongoing convection from a decaying MCS over parts
of eastern MO in the morning that will move into IL. However it
does appear that there will be sufficient air mass recovery in the
wake of the morning convection. How much and the most favored
corridors are hard to say. Mid level lapse rates will remain steep
and heating should lead to SBCAPE of at least 1500 j/kg over parts
of central MO by early afternoon. The combination of the east-northeast
rotating short wave trof and large scale ascent, and the attendant
advancing cold front should result in thunderstorm development
along/ahead of the cold front by mid afternoon. Coverage should
then increase through the remainder of the afternoon, with storms
persisting into the evening as the front and trof progress east.
We will probably see a mixed convective mode with all severe
weather threats. Most of the activity should have moved out of the
CWA by 06z Thursday.

The trof will be lifting to the northeast on Thursday with the
cold front advancing into the OH/TN Valley region. Present
indications are that increasingly deep westerly flow in the wake
of the front will lead to good drying and little if any
precipitation.

Next round of showers and thunderstorms looks to unfold Friday
night into the weekend. First with the LLJ, WAA, and a lead
impulse Friday night/Saturday and then with another formidable
upper trof and attendant cold front Saturday night into Sunday.

Glass

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 645 PM CDT Tue Apr 26 2016

Thunderstorms have mostly moved east of the CWFA with the
exception of some continuing storms over southeast Missouri.
Another round of storms is expected late tonight...but until then
VFR flight conditions are expected. Timing and strength of the
storms is uncertain at this time...but current thinking is that
the storms will move into central Missouri after 06Z and
overspread the entire area by 11-12Z. Think conditions will
primarily be VFR, but areas of heavier rain will likely bring
visibility down to 3SM and ceilings below 3,000 FT. Lower
conditions are possible as well. Rain will clear from southeast to
northwest through the morning and the atmosphere will reset for
another round of strong storms Wednesday afternoon.

Specifics for KSTL:

Expect VFR flight conditions to prevail at Lambert this evening
and probably through most of the night. Another round of storms is
expected to move in from the southwest between 08-10Z. Once the
rain starts, it will likely continue intermittently through at
least 15-17Z. Think conditions will primarily be VFR, but
intermittent heavier rain will likely bring visibility down to
3SM and ceilings below 3,000 FT. Lower conditions are possible as
well. Rain will clear from southeast to northwest through the
morning and the atmosphere will reset for another round of strong
storms Wednesday afternoon.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 270003
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
703 PM CDT TUE APR 26 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Tue Apr 26 2016

Current bowing convective system over SW IL has a well established
cold pool and will continue to move east into the western OH
Valley into a large region of unstable air in advance of it. The
deep convective line with any severe threat should clear the area by
500 pm with trailing stratiform rain clearing the CWA by early
evening. A prominent outflow boundary with the convective system,
which should have completely moved through the CWA by 00z, has
largely stabilized the air mass to boundary layer based storms in
its wake. I will retain some low chance pops this evening on the
fringes of our CWA however I think the vast majority of the
evening in the wake of the present system will be dry. Current
thinking is that overnight we will see a MCS that has evolved
across the Plains early this evening, move west to east into central
and finally eastern MO in the predawn hours. Additional showers
and thunderstorms could develop late this evening and overnight
ahead of the aforementioned progressive Plains MCS in response to
the LLJ and WAA along north of the retreating outflow boundary/warm
front composite. There will be a severe threat with this overnight
activity given MUCAPE of 1000+ j/kg and increasing southwesterly
deep layer shear, but not nearly as great as the system that moved
through today.

Glass

.LONG TERM...  (Wednesday through Next Tuesday)
Issued at 332 PM CDT Tue Apr 26 2016

A little unclear how everything will pan out on Wednesday. There
will likely be ongoing convection from a decaying MCS over parts
of eastern MO in the morning that will move into IL. However it
does appear that there will be sufficient air mass recovery in the
wake of the morning convection. How much and the most favored
corridors are hard to say. Mid level lapse rates will remain steep
and heating should lead to SBCAPE of at least 1500 j/kg over parts
of central MO by early afternoon. The combination of the east-northeast
rotating short wave trof and large scale ascent, and the attendant
advancing cold front should result in thunderstorm development
along/ahead of the cold front by mid afternoon. Coverage should
then increase through the remainder of the afternoon, with storms
persisting into the evening as the front and trof progress east.
We will probably see a mixed convective mode with all severe
weather threats. Most of the activity should have moved out of the
CWA by 06z Thursday.

The trof will be lifting to the northeast on Thursday with the
cold front advancing into the OH/TN Valley region. Present
indications are that increasingly deep westerly flow in the wake
of the front will lead to good drying and little if any
precipitation.

Next round of showers and thunderstorms looks to unfold Friday
night into the weekend. First with the LLJ, WAA, and a lead
impulse Friday night/Saturday and then with another formidable
upper trof and attendant cold front Saturday night into Sunday.

Glass

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 645 PM CDT Tue Apr 26 2016

Thunderstorms have mostly moved east of the CWFA with the
exception of some continuing storms over southeast Missouri.
Another round of storms is expected late tonight...but until then
VFR flight conditions are expected. Timing and strength of the
storms is uncertain at this time...but current thinking is that
the storms will move into central Missouri after 06Z and
overspread the entire area by 11-12Z. Think conditions will
primarily be VFR, but areas of heavier rain will likely bring
visibility down to 3SM and ceilings below 3,000 FT. Lower
conditions are possible as well. Rain will clear from southeast to
northwest through the morning and the atmosphere will reset for
another round of strong storms Wednesday afternoon.

Specifics for KSTL:

Expect VFR flight conditions to prevail at Lambert this evening
and probably through most of the night. Another round of storms is
expected to move in from the southwest between 08-10Z. Once the
rain starts, it will likely continue intermittently through at
least 15-17Z. Think conditions will primarily be VFR, but
intermittent heavier rain will likely bring visibility down to
3SM and ceilings below 3,000 FT. Lower conditions are possible as
well. Rain will clear from southeast to northwest through the
morning and the atmosphere will reset for another round of strong
storms Wednesday afternoon.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 270003
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
703 PM CDT TUE APR 26 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Tue Apr 26 2016

Current bowing convective system over SW IL has a well established
cold pool and will continue to move east into the western OH
Valley into a large region of unstable air in advance of it. The
deep convective line with any severe threat should clear the area by
500 pm with trailing stratiform rain clearing the CWA by early
evening. A prominent outflow boundary with the convective system,
which should have completely moved through the CWA by 00z, has
largely stabilized the air mass to boundary layer based storms in
its wake. I will retain some low chance pops this evening on the
fringes of our CWA however I think the vast majority of the
evening in the wake of the present system will be dry. Current
thinking is that overnight we will see a MCS that has evolved
across the Plains early this evening, move west to east into central
and finally eastern MO in the predawn hours. Additional showers
and thunderstorms could develop late this evening and overnight
ahead of the aforementioned progressive Plains MCS in response to
the LLJ and WAA along north of the retreating outflow boundary/warm
front composite. There will be a severe threat with this overnight
activity given MUCAPE of 1000+ j/kg and increasing southwesterly
deep layer shear, but not nearly as great as the system that moved
through today.

Glass

.LONG TERM...  (Wednesday through Next Tuesday)
Issued at 332 PM CDT Tue Apr 26 2016

A little unclear how everything will pan out on Wednesday. There
will likely be ongoing convection from a decaying MCS over parts
of eastern MO in the morning that will move into IL. However it
does appear that there will be sufficient air mass recovery in the
wake of the morning convection. How much and the most favored
corridors are hard to say. Mid level lapse rates will remain steep
and heating should lead to SBCAPE of at least 1500 j/kg over parts
of central MO by early afternoon. The combination of the east-northeast
rotating short wave trof and large scale ascent, and the attendant
advancing cold front should result in thunderstorm development
along/ahead of the cold front by mid afternoon. Coverage should
then increase through the remainder of the afternoon, with storms
persisting into the evening as the front and trof progress east.
We will probably see a mixed convective mode with all severe
weather threats. Most of the activity should have moved out of the
CWA by 06z Thursday.

The trof will be lifting to the northeast on Thursday with the
cold front advancing into the OH/TN Valley region. Present
indications are that increasingly deep westerly flow in the wake
of the front will lead to good drying and little if any
precipitation.

Next round of showers and thunderstorms looks to unfold Friday
night into the weekend. First with the LLJ, WAA, and a lead
impulse Friday night/Saturday and then with another formidable
upper trof and attendant cold front Saturday night into Sunday.

Glass

&&

.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 645 PM CDT Tue Apr 26 2016

Thunderstorms have mostly moved east of the CWFA with the
exception of some continuing storms over southeast Missouri.
Another round of storms is expected late tonight...but until then
VFR flight conditions are expected. Timing and strength of the
storms is uncertain at this time...but current thinking is that
the storms will move into central Missouri after 06Z and
overspread the entire area by 11-12Z. Think conditions will
primarily be VFR, but areas of heavier rain will likely bring
visibility down to 3SM and ceilings below 3,000 FT. Lower
conditions are possible as well. Rain will clear from southeast to
northwest through the morning and the atmosphere will reset for
another round of strong storms Wednesday afternoon.

Specifics for KSTL:

Expect VFR flight conditions to prevail at Lambert this evening
and probably through most of the night. Another round of storms is
expected to move in from the southwest between 08-10Z. Once the
rain starts, it will likely continue intermittently through at
least 15-17Z. Think conditions will primarily be VFR, but
intermittent heavier rain will likely bring visibility down to
3SM and ceilings below 3,000 FT. Lower conditions are possible as
well. Rain will clear from southeast to northwest through the
morning and the atmosphere will reset for another round of strong
storms Wednesday afternoon.

Carney

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





000
FXUS63 KLSX 262108
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
408 PM CDT TUE APR 26 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 332 PM CDT Tue Apr 26 2016

Current bowing convective system over SW IL has a well established
cold pool and will continue to move east into the western OH
Valley into a large region of unstable air in advance of it. The
deep convective line with any severe threat should clear the area by
500 pm with trailing stratiform rain clearing the CWA by early
evening. A prominent outflow boundary with the convective system,
which should have completely moved through the CWA by 00z, has
largely stabilized the air mass to boundary layer based storms in
its wake. I will retain some low chance pops this evening on the
fringes of our CWA however I think the vast majority of the
evening in the wake of the present system will be dry. Current
thinking is that overnight we will see a MCS that has evolved
across the Plains early this evening, move west to east into central
and finally eastern MO in the predawn hours. Additional showers
and thunderstorms could develop late this evening and overnight
ahead of the aforementioned progressive Plains MCS in response to
the LLJ and WAA along north of the retreating outflow boundary/warm
front composite. There will be a severe threat with this overnight
activity given MUCAPE of 1000+ j/kg and increasing southwesterly
deep layer shear, but not nearly as great as the system that moved
through today.

Glass

.LONG TERM...  (Wednesday through Next Tuesday)
Issued at 332 PM CDT Tue Apr 26 2016

A little unclear how everything will pan out on Wednesday. There
will likely be ongoing convection from a decaying MCS over parts
of eastern MO in the morning that will move into IL. However it
does appear that there will be sufficient air mass recovery in the
wake of the morning convection. How much and the most favored
corridors are hard to say. Mid level lapse rates will remain steep
and heating should lead to SBCAPE of at least 1500 j/kg over parts
of central MO by early afternoon. The combination of the east-northeast
rotating short wave trof and large scale ascent, and the attendant
advancing cold front should result in thunderstorm development
along/ahead of the cold front by mid afternoon. Coverage should
then increase through the remainder of the afternoon, with storms
persisting into the evening as the front and trof progress east.
We will probably see a mixed convective mode with all severe
weather threats. Most of the activity should have moved out of the
CWA by 06z Thursday.

The trof will be lifting to the northeast on Thursday with the
cold front advancing into the OH/TN Valley region. Present
indications are that increasingly deep westerly flow in the wake
of the front will lead to good drying and little if any
precipitation.

Next round of showers and thunderstorms looks to unfold Friday
night into the weekend. First with the LLJ, WAA, and a lead
impulse Friday night/Saturday and then with another formidable
upper trof and attendant cold front Saturday night into Sunday.

Glass

&&

.AVIATION...  (For the 12z TAFs through 12z Wednesday Morning)
Issued at 645 AM CDT Tue Apr 26 2016

Outside of some patchy MVFR CIGs in the north around UIN, VFR
conditions (outside of TSRA) are expected to prevail for the TAF
sites thru this evening. A cluster of TSRA is expected to roll
down from the KS-MO-NE junction this morning and affect COU and
the STL metro sites later this morning and early afternoon. A
brief period of gusty winds at the onset is also expected. A
frontal boundary is then anticipated to stall just north of I-70
for tonight and should promote low CIG formation for areas to the
north, including UIN, with MVFR CIGs returning there and perhaps
dropping into IFR category. Widespread rain and TSRA is then
expected to overspread the region later this evening and
overnight.

TES

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX





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