Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 020821

321 AM CDT FRI OCT 2 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 311 AM CDT Fri Oct 2 2015

Relatively strong surface ridge extends from northwestern WI south-
southwest into north central OK.  Gusty northeast winds can be
expected today due to the fairly tight surface pressure gradient
across the region.  East-northeasterly low level, 850 mb winds will
bring increasing moisture and cloudiness westward into portions of
east central and southeast MO and southwest IL later today north-
northwest of the mid-upper level low and associated weak inverted
surface trough over the Gulf Coast states into the Tennessee Valley
region.  These clouds along with weak low level cold air advection
and 850 mb temperatures of only about 8-10 degrees C over our area
will hinder daytime heating today.  High temperatures today will be
a tad cooler than yesterday, and about 5 degrees below normal for
early October.


.LONG TERM:  (Tonight through Thursday)
Issued at 311 AM CDT Fri Oct 2 2015

Cutoff low forming over the southeast U.S. in the base of the
eastern CONUS longwave trof is forecast to wobble southeast over the
next few days and nights, and eventually interact with Joaquin as it
works its was north from the Bahamas.  The very slow eastward
progression of this feature. along with the development of the upper
low over the southwestern U.S., means very little movement of
weather features across the central CONUS over the next few days and
nights. This atmospheric traffic jam will keep surface ridging
locked over the area tonight into Monday.

Low level moisture which begins to work into the area today should
increase tonight and into the weekend due to an intensification
of the easterly flow produced by the increase of the pressure
gradient between aforementioned surface ridge and lowering
pressures over the southeast U.S. 00z guidance supports earlier
model trends of indicating a westward surge of this low level
moisture, and plan view RH progs as well as forecast soundings
suggest this cloudiness gradually spreading west across the FA
tonight into Sunday morning. Have attempted to tweak temp trends
to reflect this increase in cloudiness, with clouds tending to
limit the diurnal swing in the mercury as they move into an area.

Can`t totally rule out a slight threat of showers with increase of
low level moisture, but at this point will keep forecast dry as
moisture is rather statified with an apparent lack of any pronounced
dynamics/lift over the mid-Mississippi Valley.

Upper pattern over the CONUS should become progressive once again early
next week as the combo of Joaquin and southeast U.S. cutoff begin
to propagate up the east coast and into the western Atlantic.
Specifics of medium range forecasts remain rather chaotic, but
there does seem to be some agreement that remnants of low over the
southwest U.S. will press into the central CONUS by Wednesday
night/Thursday, so have continued some low PoPs during this time



.AVIATION:  (For the 06z TAFs through 06z Friday Night)
Issued at 1122 PM CDT Thu Oct 1 2015

Clear skies at the moment across the region with a light northerly
breeze. Latest guidance suggests area of MVFR ceilings developing
or advecting west shortly after sunrise across the St. Louis Metro
terminals. Have hinted at this with a SCT020, as confidence is not
high enough to include MVFR ceilings at this point. In any case,
ceiling should lift and scatter out in the afternoon with a gusty
northerly wind.

Specifics for KSTL:

Potential for a MVFR deck to form and advect west across the
terminal after 12Z. Have hinted at this in the latest forecast.
Otherwise, VFR conditions with diurnal cloud cover and a gusty
north wind.



Saint Louis     66  50  65  52 /   5   5   5   5
Quincy          65  44  63  47 /   0   0   0   5
Columbia        65  44  64  47 /   0   0   0   5
Jefferson City  67  45  66  47 /   0   0   0   5
Salem           66  50  63  52 /  10  10  10  10
Farmington      64  47  63  49 /   5   5   5   5




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