Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 240937
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
337 AM CST Tue Feb 24 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 334 AM CST Tue Feb 24 2015

SFC ridge has settled just south of the area early this mrng with
sthrly winds at almost all stations within the CWA with a few
exceptions across the ern zones. Temp trends across the area
overnight have been a challenge to say the least with various
combinations of bare ground vs. snow cover...clouds vs. no clouds
and sthrly winds vs. calm winds. Deck of mid clouds across southern
IL/MO will continue to push east and out of the area drng the
mrng. This will set the stage for a nice warm up...esp for areas
lacking significant snow cover. Full sunshine and a favorable wind
direction from the W/WSW in advance of the next bndry means temps
should rise into the 40s along the I70 corridor where snow cover
is nonexistent west of the STL metro area. Going fcst may very
well not be warm enough in those locations. Think there will be
pretty decent temp gradients on either side of this area though
due to significant snow cover. The next cold front begins pushing
into the nthrn portions of the FA late this aftn. Mid/high clouds
are expected to move into the nthrn zones later today but should
not significantly affect temp trends.

2%

.LONG TERM:  (Tonight through Monday)
Issued at 334 AM CST Tue Feb 24 2015

Weak frontal boundary to slide south through forecast area
tonight with just an increase in cloud cover initially. Lows will
be in the mid teens to low 20s.

Then northern stream clipper system to slide into region Wednesday
morning. Decent energy with this shortwave with plenty of WAA and
enough moisture to see snow accumulations up to 3 inches, with
highest amounts over northeast Missouri. The system is a bit slower
exiting region, so raised pops a bit on Thursday before coming to an
end. Will see highs in the upper 20s to upper 30s on Wednesday
before dropping off into the teens and 20s Thursday and Friday as
colder air filters in. Wind chill indicies will be between zero and
10 below Thursday night...but above wind chill advisory criteria for
now.

Beyond that, the forecast for the weekend and into early next week
remains rather messy with extended models showing a prolonged period
of precipitation across the region. The temperature profiles still
show a mixed bag of precipitation types, so just made minor
adjustments to the forecast. Will see a wintry mix at onset Saturday
through early Sunday before warmer temps move in giving portions of
the area a cold rain before transitioning back to snow Sunday night
and beyond. Will need to keep an eye on this system with subsequent
model runs as exact track of this system is crucial to what kind of
precipitation we get.

Byrd
&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1000 PM CST Mon Feb 23 2015

VFR flight conditions are expected to continue across the forecast
area through Tuesday into Tuesday night. High pressure is drifting
east and wind is already starting to turn around to the south on
the western side of the high. Wind will continue to veer to the
south-southwest through the remainder of the night. Still
expecting some marginal low level wind shear across northern
Missouri and west central Illinois as winds aloft increase on the
west side of the high. Ceilings AOA 10,000 FT will persist south
of the I-70 corridor, but should break out after 12Z. Expect winds
to increase to 10-15kts with gusts to around 20kts during the morning.
A weak cold front will move into the forecast area during the late
afternoon, shifting the wind to the west northwest. Could see some
lower ceilings with the front, but it`s not clear yet whether the
clouds will be below 3,000 FT.

Specifics for KSTL:

VFR flight conditions are expected to prevail through Tuesday
into Tuesday night. High pressure is drifting east and wind will turn
around to the south on the western side of the high. Ceilings AOA
10,000 FT will persist south of the I-70 corridor, and it looks
like these clouds will just scrape by to the south of Lambert. Expect
winds to increase to 10-15kts with gusts to around 20kts in the morning.
A weak cold front will move into the area during the early
evening, shifting the wind to the west northwest. Could see some
lower ceilings with the front, but it`s not clear yet whether the
clouds will be below 3,000 FT.

Carney
&&

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

$$
WFO LSX




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