Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 160943
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
343 AM CST Fri Feb 16 2018

.SHORT TERM...  (Through Late Tonight)
Issued at 342 AM CST Fri Feb 16 2018

A cold front was moving southward early this morning and will
likely have moved through the rest of the CWA before sunrise.
Today`s gusty northwest winds with highs in the 30s-40s will provide
a sharp contrast to yesterday`s record and near-record warmth.
Overnight lows should be in the 20s across the area.

Ongoing rain in the vicinity of the front will taper off through the
morning hours, and most areas should be dry by afternoon. There may
be some isolated pockets of a rain/snow mix at times this morning
due to the arrival of the colder air. Gusty northwest winds will
decrease this evening and then become southeasterly to southerly
very late tonight in response to a surface high pressure center
moving across MO/IA/IL.

Kanofsky

.LONG TERM...  (Saturday through Thursday)
Issued at 342 AM CST Fri Feb 16 2018

The sfc ridge in control of the region Fri night quickly builds east
with sly flow returning to the area by Sat morning. Expect two areas
of precip on Sat. One along a weak cdfnt impacting nrn portions of
the CWA and the second associated with a leading s/w and WAA
impacting the srn portions of the CWA. P-type across the south shud
begin as snow as any WAA is countered with wetbulb effects. However,
this will gradually transition to rain as the low levels warm thru
the morning. Expect the ground to still be fairly warm and with
precip intensity expected to be fairly light, have kept snow accums
lower. Precip chances diminish fairly quickly during the afternoon
hours as the trof passes to the east.

With sly to swly flow at low levels on Sat and even more so on Sun,
have trended twd the warmer guidance, especially on Sun.

Warm trends continue on Mon with deep swly flow. Mdls suggest a slow
moving cdfnt pushing into the CWA late Mon night into Tues. This
front is expected to very slowly move south until the upper trof
finally pushes it south of the CWA by Wed morning. A number of
questions remain regarding this front. Among them, how much rain the
region will receive, chance for severe weather tho have continued
chance for thunder. After a clearly warm day on Mon, more
uncertainty exists for Tues and potentially even Wed. For now, have
trended twd a compromise for Tues, then twd cooler guidance for Wed.


Tilly

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1138 PM CST Thu Feb 15 2018

The cold front has passed south of I-70 and is now near the I-44
corridor. IFR flight conditions in rain along the front will move
southeast out of the area through early morning, but another area
of low ceilings now over northern Missouri will spread southeast
to affect most of the area by sunrise Friday. Currently the
ceilings are MVFR, and guidance keeps the heights above 900 feet
through Friday morning. I cannot rule out a few areas going IFR
though before the clouds move out during the late morning and
early afternoon on Friday. Northwest flow around 15kts sustained
with gusts up to 30kts will prevail into the morning and diminish
during the afternoon.

SPECIFICS FOR KSTL:

The front has moved south of the terminal and it looks like precip
has ended for the time being. Another area of showers is
developing over west central Missouri...and this may move over the
terminal during the pre-dawn hours of Friday morning, but
precipitation looks very light if it does occur. Primary concern
will be low ceilings currently over northern Missouri building
south to affect the terminal before 12Z. Timing and height is
uncertain, but most guidance shows the clouds moving in between
10-12Z at around 2000 feet. Cannot rule out lower ceilings and so
kept tempo 1500 for a few hours in the morning. Clouds should
clear/scatter out by early afternoon.

Carney

&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     40  30  48  32 /  10   5  50   5
Quincy          33  23  46  27 /   5   0  20   0
Columbia        38  27  50  30 /   5   5  50   0
Jefferson City  40  27  50  29 /   5   5  50   0
Salem           41  27  44  30 /  30   5  40   5
Farmington      42  27  47  29 /  40  10  70   5

&&

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

$$

WFO LSX



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