Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 180913
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
313 AM CST Tue Nov 18 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 310 AM CST Tue Nov 18 2014

A deep upper level TROF axis existed from the western Great Lakes to
the Lower MS Valley, which isn`t much different than where it was
24hrs ago.  Individual disturbances continue to rotate around the
backside of this TROF, with one in particular from MN to near the
Mid-MO Valley that has mainly resulted in a large area of clouds,
with some scattered flurries as well.  W-NW surface flow was
currently prevailing with decent speeds of 10mph or greater.  When
combined with actual temperatures in the single digits and lower
teens, wind chills as low as 10 below are resulting.  Besides the
large area of clouds to our northwest, skies were otherwise clear
for most of our forecast area.

The flow at cloud level is currently from the NW and is helping to
advect the large area of clouds towards our region early this
morning.  Over time, however, the flow is expected to back and
become more from the W by midday.  The result should be for this
area of clouds to mainly impact areas in northeast MO and central
IL.  Add to that what should be a decently healthy diurnal component
to the clouds again today, thanks to the stout thermal TROF in the
area, look for skies to at least become partly cloudy for our region
later this morning.  By this afternoon, the thermal TROF aloft will
shift east into IL more and this should result in the cloud shield
shifting east with it, giving IL partly sunny to mostly cloudy skies
and mostly sunny skies in central MO.  A few flurries will also be
possible in IL this afternoon.

Despite the very cold start this morning, daytime max temps should
be warmer than persistence for the MO side of the river thanks to
decent levels of sunshine and surface flow becoming more W-SW,
promoting deeper mixing layers and strongly favoring the higher MAV
MOS.  Where the clouds are more numerous in IL, persistence a good
forecast guess where MOS blend preferred.

TES

.LONG TERM:  (Tonight through Monday)
Issued at 310 AM CST Tue Nov 18 2014

(Tonight through Thursday)

Winds will become sly tonight ahead of the approaching cdfnt. This,
coupled with increasing cloud cover, will cause temps to rise after
a quick drop this evening. Have trended lows tonight just below the
warmer guidance for tonight. Given the timing of the cdfnt late
tonight into tomorrow, have trended temps twd cooler guidance across
nrn portions of the CWA for Wed, while trending warmer across the S.
With the sfc ridge building into the region for Thurs, have trended
temps cooler compared to the prev forecast. However, remained on the
warmer side compared to guidance due to low confidence in timing of
features.

Expect this period to remain dry. However, best chances for precip
will be late tonight and Wed as the cdfnt pushes thru the region.
Mdls continue to show a lack of moisture with this fnt. Clouds
associated with it appear to be mainly mid deck. Can not completely
rule out flurries, especially over ern portions of the CWA, but will
keep a dry forecast for now.

(Friday through Monday)

Focus quickly turns to the approaching system impacting the region
beginning Fri. This system is currently a closed low over the ern
Pacific due W of nrn California. This low is progd to open and break
down the ridge currently over the wrn U.S. Mdls have sped up the
timing of this initial s/w by at least 12 hrs compared to the 00z
mdl solns from yesterday. Have low confidence in this soln since the
low is still over open water and due to poor run to run consistency.
Concern of p-type still remains as the retreating sfc ridge pulls
ewd as the s/w approaches. Latest guidance suggests sfc temps will
be just warm enuf to suggest precip will fall as RA. As mentioned,
low confidence in mdl solns may lead to more changes in p-type as
the system approaches.

Have trended twd the warmer guidance Fri thru Sun with height rises
and the pattern becoming more zonal. This warm-up will be short
lived as a persistent trof is progd to remain in place by Mon.
However, latest mdl solns appear that it will not be as cold as the
current conditions.

Tilly

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1204 AM CST Tue Nov 18 2014

Some lingering sc with light snow will continue to track southeast
along Mississippi River. Coverage is small, so just have low end
vfr cigs through 07z for metro area tafs with gusty winds. Then sc
clears out and winds lose gusts. Winds to pick back up by mid
morning from the west before diminishing towards sunset once
again  and back to the south.

Specifics for KSTL:
Some lingering sc with light snow will continue to track southeast
along Mississippi River. Coverage is small, so just have low end
vfr cigs through 07z for metro area tafs with gusty winds. Then sc
clears out and winds lose gusts. Winds to pick back up by mid
morning from the west before diminishing towards sunset once
again and back to the south.

Byrd

&&

.CLIMATE:

The following are record low maximums and record low minimums today.

Date:       11/18

          St. Louis

Low High:  25/1880
     Low:  14/1932

          Columbia

Low High:  27/1903
     Low:   8/1891

           Quincy

Low High:  24/1903
     Low:   7/1903


&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     28  25  41  21 /   5   5  10   0
Quincy          24  20  32  16 /   5  10  10   0
Columbia        31  24  37  17 /   0   5  10   0
Jefferson City  32  25  39  18 /   0   5  10   0
Salem           24  20  40  20 /   5   0  10   0
Farmington      28  24  45  19 /   0   0  10   0

&&

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

$$

WFO LSX






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