Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 252110
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
410 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 18z TAFs through 18z Thursday Afternoon)
Issued at 100 PM CDT Wed Mar 25 2015

Busy fcst prd with significant system passing thru the center of
the country. A warm front extends from a sfc low across
panhandles of OK/TX to SE ME and sthrn IL on into OH vly.
Meanwhile...a cold front is currently pushing SE thru IA/KS and
has made it into ntrhn MO. The low will track along the sthrn
front and is fcst to move from the sthrn Plains today to the OH
vly tomorrow. These systems will combine with upper lvl energy to
produce widespread rain and TSTMs across the area from this aftn
thru the night and should be pushing east of the STL metro terminals
by 12Z Thursday. IFR stratus continues to erode to the north early
this aftn....extending from MHL to MYJ to PPQ to 3LF to SLO. KUIN
is expected to be on the edge of the clearing this aftn and CIGs
may not dsspt as CIGs are expected to fill in behind the advancing
cold front. May be too optimistic with CIG fcst for KUIN this
aftn/evng. An area of SHRA/TSMS has dvlp across SE KS/SW MO. This
activity is expected to increase in coverage as it moves NE arriving
in KCOU around 21Z-22Z. Precip is expected to continue to expand
to the NE this evng lasting most of the night along and south of
I44 in MO and I70 in IL. CIGs tonight may be lower than fcst as
models indicate IFR CIGs dvlpng...but held off til a start time
can be better established. Model consensus clears any low CIGs out
around 12Z with skies clearing drng the mrng and NNW winds the
rest of the day.

Specifics for KSTL:

VFR fcst til 00Z...then a several hr prd of possible TSTMs with
persistent rain the rest of the night. Models indicate the CIG
fcst for tonight may not be low enough with IFR CIGs a possibility.
Any low CIGs that dvlp are expected to clear around 12Z with VFR
conditions expected tomorrow with skies clearing drng the mrng and
NNW winds.

2%

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     40  52  34  47 / 100  40  10  10
Quincy          34  48  28  42 /  70   5   5  10
Columbia        37  52  32  48 /  90  10  20  10
Jefferson City  38  52  33  49 /  90  10  20  10
Salem           42  51  32  45 / 100  70   5  10
Farmington      39  51  32  47 / 100  60  10  20

&&

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

IL...FLASH FLOOD WATCH through Thursday morning FOR Clinton IL-Marion
     IL-Monroe IL-Randolph IL-St. Clair IL-Washington IL.

&&

$$

WFO LSX





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