Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 080919
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
319 AM CST MON FEB 8 2016

.SHORT TERM: (Today and Tonight)
Issued at 300 AM CST Mon Feb 8 2016

Previous forecast is pretty much on track. Large scale amplification
is underway with lead shortwave centered through IL and initial
cold front well to the east. Secondary cold front/surge is through
KUIN/KPPQ and KCOU at 08z with the next weaker upstream vort max
stretching from the upper low in WI into western IA. This second
cold front will blast through the area this morning as the vort
max rotates s/se, accompanied by gusty northwest winds, strong CAA
and falling temperatures. Regional radars don`t seem to give
justice to the snow especially from northern MO into southern IA.
Snow showers, snow bands - they will spread southeast across the
area this morning in association with the aforementioned vort max
rotating southeastward. Model soundings continue to exhibit steep
low level lapse rates and strong unidirectional shear in the
lowest few km, supportive of HCRs/snow showers with conditions
becoming less favorable from north to south late morning into the
afternoon. Snow accumulations are not expected to be much and
could be highly variable with some spots seeing not much more than
a trace or dusting and others up to a half inch, and in highly
isolated spots possibly upwards of an inch. The potential for
light snow showers and/or flurries will continue this evening,
albiet lower, gradually shunting east of the MS River into IL
overnight as the upper low moves east into the lower Great
Lakes/Ohio Valley region.

Glass

.LONG TERM: (Tuesday through Sunday)
Issued at 300 AM CST Mon Feb 8 2016

The deep expansive upper trof will dominate the eastern 2/3rds of
the Nation through Wednesday resulting in winter cold with 15-20
degree below average temperatures. During the later half of the
week there is a general trend towards some deamplification of the
upper trof with a very broad cyclonic flow from the Rockies
eastward. Initially this will result in a slight moderation of
temperatures, however they will remain below average. The ECMWF is
supported by the GEFS showing another formidable surge of cold air
on Friday as the upper trof deepens again over the eastern U.S.
Confidence is high enough that forecast temps are now trended
colder for Sat/Sun. Still some questions on a precipitation event
Sunday into Monday. There is little run to run consistency in the
deterministic solutions and confidence is low at this point in
time.

Glass

&&

.AVIATION:  (For the 06z TAFs through 06z Monday Night)
Issued at 1136 PM CST Sun Feb 7 2016

Upper-level trough continues to dig southward and this will help
bring both much colder air to the region but also some
predominantly scattered snow showers through much of the period.
These snow showers may briefly reduce visibilities and ceilings
down into IFR. Otherwise...expect gusty NW winds along with a
high-end MVFR ceilings along with the snow showers/flurries.


Specifics for KSTL:

Timing of MVFR ceilings and snow showers still appears to be in
the predawn hours of Monday morning. Once again...some of these
snow showers may be heavy enough at times through Monday morning
to reduce visibilities and ceilings down to IFR. Best chances of
these heavier snow showers/squalls for the terminal attm appear to
be in the 1000 and 1600 UTC range give or take a couple of hours.
Otherwise...NW winds will pick up with gusts near 30 knots along
with ceilings between 2500 and 3000 ft AGL.

Gosselin

&&

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

$$

WFO LSX


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