Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 261128
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
528 AM CST Thu Feb 26 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 308 AM CST Thu Feb 26 2015

Shortwave digging over northeast Missouri and associated cold front
now moving through the I-44 corridor will continue to produce light
snow through the first part of the morning.  Have also had a few
reports of freezing drizzle back in central Missouri, but not sure
how long this will last so have opted not to mention in the forecast
at this time.  Will continue to monitor and update if freezing
drizzle ends up persisting.  Both NAM and GFS show some decent low
level frontogenetical forcing back on the cold side of the front
before 12Z this morning...but the forcing quickly diminishes between
12Z and 15Z.  Mesoscale models do keep light snow going for a few
hours this morning, but really back off the precip by 15Z like the
operational models.  Both NSSL and NCEP 4km WRF models pop up what
look like instability snow showers this afternoon, so have kept
chance PoPs going into the afternoon primarily along and east of the
Mississippi River.  Total accumulations of 1 inch or less look
likely along and south of the I-70 corridor with 1-3 inches north
and northeast of St. Louis...primarily across west central and parts
of southwest Illinois.  Will continue headlines as they are this
morning.  Stuck close to the cold side of guidance for temperatures
today as the cold Arctic high moves in behind the cold front.

Carney

.LONG TERM:  (Tonight through Wednesday)
Issued at 527 AM CST Thu Feb 26 2015

Arctic high builds overhead tonight into Friday.  Doesn`t look like
we`ll set any record lows Friday morning, however widespread
temperatures near or below zero can be expected from central and
northeast Missouri into west central Illinois with single digits
elsewhere.  With the cold start to the morning, it`s likely
temperatures will struggle to make the teens on Friday.  Southerly
flow develops Friday night into Saturday and while it should be
warmer, temperatures will still be well below normal.

Looks like an active weather pattern coming up for late Saturday
into next week.  The persistent ridge over the western CONUS/eastern
Pacific that we`ve been dealing with for the past several weeks is
breaking down and it looks like we`ll get into a southwest flow
regime by late Saturday and into Sunday.  While this means we will
most likely see warmer temperatures, it also looks like a much
wetter pattern than we`ve had recently.  Have several periods of
likely PoPs headed out into the medium range beginning late Saturday
continuing into Saturday night and Sunday in a warm advection
pattern.  Precipitation types are difficult to pin down at this time
with the receding Arctic airmass potentially causing a wintry mix.
Another bout of warm advection precip develops on Monday night and
continues into Tuesday.  Again, low level temperatures will likely
dictate what falls, but there may be more liquid rain than wintry
mix, especially into Tuesday with good southerly flow developing at
the surface.  Regardless, this will be a challenging forecast due to
the mixed precip types and inherent difficulty in forecasting
shallow layers in the medium range.

Carney

&&

.AVIATION:  (For the 06z TAFs through 06z Thursday Night)
Issued at 1139 PM CST Wed Feb 25 2015

Reduced SN at COU as much of the precip across that region has
dissipated. SN at UIN shud gradually diminish thru the early
morning hours as the system pulls sewd. With cigs beginning to
rise, going TAF may hold on to SN too long. However, with sparse
RADAR coverage across this area, it is difficult to determine how
far SE some of the heavier bands stretch. Otherwise, winds will
remain nly with gusts to around 25 kts into the afternoon hrs.
Believe cigs will be slow to rise and going forecast may break up
clouds too quickly.

Specifics for KSTL/KSUS/KCPS: Believe SN will begin shortly before
sunrise. SN will gradually diminish thru the morning with cigs
slow to rise. Given how cold temps will be, can expect light SHSN
periods of flurries thru the day. Otherwise, winds will remain nly
with gusts to around 25 kts thru the afternoon hrs. Believe cigs
will be slow to rise and going forecast may break up clouds too
quickly.

Tilly

&&

.PRELIMINARY POINT TEMPS/POPS:
Saint Louis     24   3  17   7 /  90  10   0   5
Quincy          14  -6  11   0 /  50   5   0   5
Columbia        18   0  16   7 /  40   5   0   5
Jefferson City  21   2  18   8 /  50   5   0   5
Salem           24   2  14   6 /  70  10   0   5
Farmington      24   4  18   7 /  60  10   0   5

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...WINTER WEATHER ADVISORY until 9 AM CST this morning FOR Knox MO-
     Lewis MO-Marion MO-Monroe MO-Ralls MO-Shelby MO.

IL...WINTER WEATHER ADVISORY until 9 AM CST this morning FOR Adams IL-
     Brown IL-Pike IL.

&&

$$

WFO LSX





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