Area Forecast Discussion
Issued by NWS St. Louis, MO

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677
FXUS63 KLSX 051716
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1116 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 a loft 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 positively 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 blusteryconditions
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 deamplifies 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 18z TAFs through 18z Saturday Afternoon)
Issued at 1108 AM CST Fri Feb 5 2016

VFR through the period with increasing mid/high clouds. Initially
lgt/var winds will become southwesterly on Saturday morning due
to the approach and passage of a surface trough after 06/12z.

Kanofsky

&&

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

$$

WFO LSX



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