Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 010803

Area Forecast Discussion
National Weather Service Saint Louis MO
303 AM CDT SUN MAY 1 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 302 AM CDT Sun May 1 2016

Patchy dense fog over northeast Missouri, west central Illinois to
dissipate and thin out towards daybreak. So main issue for today
will be the closed upper level low currently over south central
Nebraska that will finally open up and slide east across northern
Missouri. Will see scattered showers and a few thunderstorms
possible, especially along and north of I70 in Missouri and along
and east of Mississippi River in Illinois. Some of the storms will
be strong over southwestern Illinois where CAPES will be in excess
of 1500 J/kg this morning through the afternoon hours, as well as
decent low level lapse rates and some shear. Could see some small
hail and wind gusts to 45 mph with the stronger storms.

As for high temps today, with mostly cloudy skies will have a wide
variation from the upper 50s far north to the mid 70s far southeast.


.LONG TERM...  (Tonight through Saturday)
Issued at 302 AM CDT Sun May 1 2016

Expect thunderstorms to be ongoing at the beginning of the forecast
period, but to be E of the CWA at 00z this evening.

Mdls are in fairly good agreement with upper trof hanging up over IA
on Mon with a s/w moving thru the area. While the bulk of the precip
shud remain S of the area, this s/w and cold temps aloft shud be
enuf to support SHRA across much of the area. Given the diurnal
nature of these SHRA, expect Mon night to be dry with isod to widely
sct SHRA again on Tues as the upper trof sinks thru the region. Some
uncertainty remains how much of the area will be see any precip, but
given the expected location of the upper trof Tues morning, have
kept PoPs confined to the srn two thirds of the CWA.

The next chance for precip is Wed as another cdfnt drops thru the
area. Mdls differ regarding how much moisture will be available as
the fnt moves thru. Will keep low PoPs going for ern portions of the
CWA where a s/w rotating around the back of the upper low may
provide enuf support for some SHRA. The remainder of the forecast is
dry as a large sfc ridge builds into the area.

Overall, temp forecast will remain aob seasonal avg. thru this week
with a sfc ridge in place as mentioned above. Wed shud be slightly
warmer with more insolation expected and wly to swly winds ahead of
the approaching cdfnt. The next warm up shud be Sat as an upper
ridge builds into the area with sfc winds becoming sly again.



.AVIATION...  (For the 06z TAFs through 06z Sunday Night)
Issued at 1101 PM CDT Sat Apr 30 2016

A cold front extends from a surface low near PPQ south-southwest
through southwestern AR. Scattered showers and thunderstorms
should move out of the St Louis metro area by 06Z Sunday. With
light surface winds and recent rainfall, patchy fog should develop
late tonight in the St Louis metro area and also possibly in COU
as well. Stratus clouds below 1000 feet along with visibilities
below 1SM in fog will likely continue late tonight and early
Sunday morning in UIN. Fog will gradually dissipate by late Sunday
morning with ceilings rising into the MVFR catagory by afternoon
at UIN. Scattered-broken diurnal cumulus clouds should develop
late Sunday morning and afternoon with widely scattered showers
possible in UIN during the afternoon ahead of an upper level
disturbance. Surface winds should be mainly w-nwly on Sunday with
a surface ridge building into the area from the Plains.

Specifics for KSTL: Showers and thunderstorms will likely move out
of the STL area by 06Z Sunday.  Light fog can be expected late
tonight and early Sunday morning as the wind becomes light.
Scattered to broken diurnal cumulus clouds will develop late
Sunday morning and afternoon with a w-nwly surface wind. The cloud
ceiling may lower into the MVFR catagory late Sunday night.



Saint Louis     71  52  61  49 /  20  10  20  10
Quincy          59  44  59  44 /  50  10  20  10
Columbia        64  46  60  44 /  10  10  20  10
Jefferson City  66  47  61  44 /  10  10  20  10
Salem           72  49  61  48 /  30  10  30  10
Farmington      73  47  62  45 /  10  10  30  10




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