Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 051050
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
450 AM CST FRI FEB 5 2016

.SHORT TERM: (Today and Tonight)
Issued at 300 AM CST Fri Feb 5 2016

A weak cold front stretched from western IL through east-central
MO early this morning. This front will pass through the remainder
of the CWA by midday with weak high pressure settling into the
area in its wake, and high clouds ahead of the Rockies upper trof
spreading into the MS Valley. Not alot of cooling with this system,
and highs should be quite seasonable and just a bit above average
for early Feb. Warm advection will commence this evening in the
wake of the migratory high pressure system and ahead of the
elongated postively tilted upper trof moving into the central U.S.
While there will be a good deal of clouds accompanying the trof,
the region currently looks to be void of precipitation.
Forcing/ascent remain well to the south associated with a
prominent vort max within the southern portion of the upper trof.

Glass

.LONG TERM: (Saturday through Thursday)
Issued at 300 AM CST Fri Feb 5 2016

Lots of change underway during this period as the aforementioned
upper trof shifts east and the warm advection regime persists
Saturday, Saturday night, and into early Sunday resulting in above
normal temperatures.

Winter cold however returns late Sunday. An oceanic low in the
Pacific currently near 36N/170W will deepen as it moves northeastward
towards the Gulf of AK over the next 72h. This will result in
tremendous downstream amplification by Monday, with a high
amplitude trof evolving over the western U.S. and a broad deep
trof east of the Rockies. Large height falls will occur on Sunday
into Sunday evening thru the MS Valley as the lead upper trof digs
southeastward and deepens. The attendant initial cold front/trof
on Sunday will bring a southwest to west wind shift, with most of
the early cooling coming aloft. However a secondary cold
front/surge on Sunday night will be accompanied by gusty northwest
winds, strong CAA, and a threat of light snow. Cloudy and blustry
conditions are expected on Monday with a continued threat of light
snow. Below normal cold will then persist into Tuesday and
Wednesday as the deep upper trof dominates the eastern 2/3rds of
the Nation.

Present indications are that we will see height rises aloft after
Wednesday as the flow deamplfies with the trofing aloft becoming
quite broad anchored by a vortex near Hudson Bay. This should
result in a return to above average temperatures by the end of
next week.

Glass

&&

.AVIATION:  (For the 12z TAFs through 12z Saturday Morning)
Issued at 441 AM CST Fri Feb 5 2016

Weak cold front will move through the area today providing a light
northwest wind and high level cloudiness. High pressure will
build in today in the relatively fast northwest flow pattern. The
high quickly will move east turning the winds back to southerly
by Saturday morning. Warm advection in advance of the next system
should produce plenty of VFR stratus and mid clouds late tonight
into Saturday.

Specifics for KSTL: Light west to northwest wind today as the
front has moved south of the terminal. High pressure will quickly
move east turning the wind back to southeast overnight and then
south to southwest during the day Saturday. Ceilings will stay
VFR through the period.

JPK

&&

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

$$

WFO LSX


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