Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 260450
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1150 PM CDT Wed Mar 25 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 410 PM CDT Wed Mar 25 2015

Focus for tonight will be TSRA chances and potential flooding.

Convection allowing mdls are in generally good agreement with
ongoing TSRA intensifying over the next few hours and spreading ewd
reaching the srn portions of the CWA around 00z this evening. Some
training will be possible early in the event. However, by 06z, cells
shud be more progressive and transitioning ewd withe more stratiform
precip behind the leading line thru the morning hours.

This presents a question of how much rainfall will occur overnight.
Believe threat for flooding is not as great as previously thought.
However, with the area receiving precip yesterday, TSRA expected
tonight with stratiform precip expected behind, feel the threat is
still high enuf to keep the watch going.

As for temps, have trended twd the cooler guidance with fropa
tonight.

Tilly

.LONG TERM:  (Thursday through Next Wednesday)
Issued at 410 PM CDT Wed Mar 25 2015

Precip shud be moving out of the region by 15z Thurs leaving the
remainder of the day dry. With clouds clearing, have trended twd the
warmer guidance with deep mixing expected.

Not much change from the prev forecast.  Mdls are in good agreement
with a strong s/w digging into the region Thurs night into Fri
bringing a cooler airmass into the region. Mdls are now suggesting
light precip with this s/w and have added low PoPs for this time
period. Have kept low for now, but if this signal remains
persistent, these PoPs will need to be increased drastically.
Soundings for this time period suggests SN will be possible when sfc
temps are cool enuf. Still some questions regarding p-types and will
modify as the system approaches.

Temps gradually moderate with mdls in fairly good agreement thru
next Tues. Upper air pattern becomes more zonal with a cdfnt will
bring chance of RA on Sun with another fnt bringing a chance for
TSRA on Wed into Thurs.

Tilly
&&

.AVIATION:  (For the 06z TAFs through 06z Thursday Night)
Issued at 1150 PM CDT Wed Mar 25 2015

Taf sites remain on north side of system as it slides northeast
into Ohio Valley through daybreak. Rain to taper off from north to
south over the next several hours. KUIN should be dry by 06z
Thursday, while rain will exit KCOU by 09z Thursday and metro area
by 11z Thursday. Otherwise, where it is raining, MVFR/IFR cigs and
vsbys possible, before lifting to VFR as rain exits. As for winds,
to remain north to northwest through the forecast period.

Specifics for KSTL:
Metro to remain on north side of system as it slides northeast
into Ohio Valley through daybreak. Rain to taper off from north to
south over the next several hours exiting metro area by 11z
Thursday. Otherwise, where it is raining, MVFR/IFR cigs and vsbys
possible, before lifting to VFR as rain exits. As for winds, to
remain north to northwest through the forecast period.

Byrd
&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...FLASH FLOOD WATCH until 7 AM CDT Thursday FOR Crawford MO-Iron
     MO-Jefferson MO-Madison MO-Reynolds MO-St. Francois MO-Ste.
     Genevieve MO-Washington MO.

IL...FLASH FLOOD WATCH until 7 AM CDT Thursday FOR Clinton IL-Marion
     IL-Monroe IL-Randolph IL-St. Clair IL-Washington IL.

&&

$$
WFO LSX





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