Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 261652
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1152 AM CDT MON SEP 26 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 317 AM CDT Mon Sep 26 2016

Northeast to southwest oriented frontogenetical band of rain
currently over the central CWA will push southeast of the area early
this morning as the shortwave trough moves through the region.
Expect clouds to move out of the region this morning because of the
dry air advection.  Today will be much cooler because of the cold
air advection.  Went close to the GFS MOS highs which are in the
lower 70s.

Expect clear skies tonight with light westerly winds.  Clear skies,
a light west wind, and a dry air mass will help temperature fall to
near the agreeable MOS lows.  Can`t rule out some steam fog near the
rivers, though with the dry airmass, think fog will stay close to
the rivers and won`t introduce it into the forecast at this time.

Britt

.LONG TERM...  (Tuesday through Sunday)
Issued at 317 AM CDT Mon Sep 26 2016

Northwest flow aloft will dominate the weather pattern over the Mid-
Mississippi Valley at least through the end of the week and probably
through next weekend as well.  The upper level low over the Great
Lakes on Tuesday morning will meander south into the Ohio Valley by
Wednesday night and further southeast into the Mid Appalachian
region by Thursday afternoon and evening.  This will force the only
"exciting" weather of the week to occur as a strong lobe of
vorticity rotates around the low which will drive a reinforcing
surface cold front south through the area on Wednesday.  There will
be little if any moisture return ahead of this reinforcing shot of
cool air, so current thinking is that the front will go through dry.
A sprawling ridge of high pressure stretching from southern Texas
through south central Canada will dominate the surface pattern for
the rest of the week and into the weekend.  Should make for
spectacular Fall weather with highs mainly in the low to mid 70s and
lows in the upper 40s to mid 50s.

Carney

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1135 AM CDT Mon Sep 26 2016

Northwest surface winds will back around to a westerly direction
by late this afternoon or early this evening as the surface ridge
centered over the southern Plains shifts slowly southward. A
surface low just north of the Great Lakes region will also drift
slowly southward. The surface wind will become west-southwesterly
by late tonight, albeit quite light. The wind will increase again
Tuesday morning from a westerly direction. A clear sky can be
expected through the forecast period. There may be some steam fog
in the river valleys late tonight and early Tuesday morning due to
the cool air over the warm river water which could impact SUS and
CPS, although the surface/boundary layer will be quite dry.

SPECIFICS FOR KSTL: Northwest surface winds will back around to a
westerly direction by late this afternoon or early this evening
as the surface ridge centered over the southern Plains shifts
slowly southward. A surface low just north of the Great Lakes
region will also drift slowly southward. The surface wind will
become west-southwesterly by late tonight, albeit quite light. The
wind will strengthen again Tuesday morning from a westerly
direction. A clear sky can be expected through the forecast
period.

GKS

&&

.FIRE WEATHER...
Issued at 317 AM CDT Mon Sep 26 2016

12-15 mph wind and minimum relative humidity below 30 percent
will combine with dry fuels to produce elevated fire danger across
parts of northeast Missouri and west central Illinois this
afternoon. Increasing fuel moisture to the south and southeast
should mitigate the fire danger across the rest of the area.

Carney


&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     75  56  75  54 /   5   0   0   0
Quincy          73  50  72  50 /   0   0   0   0
Columbia        72  51  75  52 /   0   0   0   0
Jefferson City  73  51  76  51 /   0   0   0   0
Salem           73  50  74  51 /  10   0   0   5
Farmington      72  49  75  52 /  10   0   0   0

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX


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