Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 242349

549 PM CST TUE NOV 24 2015

.SHORT TERM: (Tonight through Thanksgiving Night)
Issued at 331 PM CST Tue Nov 24 2015

Surface ridge continues to move eastward bringing increased moisture
into the area with a southerly flow ahead of cold front. ECMWF/NAM
have slowed the movement of the front which lowers the precip
chances on Wednesday. Rain chances increase from Wednesday night
into Thanksgiving evening, especially in the northwest corner of the
region as the front progresses toward the area. Temps for the
forecast period increase as southerly winds continue.


.LONG TERM: (Friday through Next Tuesday)
Issued at 331 PM CST Tue Nov 24 2015

Behind the cold front...temperatures will cool back to near normal
during the day and slightly above normal at night. Unsettled
conditions with a mostly cloudy to overcast sky and at least small
chances of light rain each forecast period. Best chance of
widespread rain looks to be early on Friday but likely PoPs continue
for portions of southeastern Missouri and southwest Illinois through
Saturday night as a sfc low travels northeastward roughly along the
Ohio River.

Some chance of rain however will remain at least for portions of the
area all the way into Tuesday as broad southwest mid/upper level
flow continue over the mid-Mississippi Valley. Closed upper-level
low looks to finally move into the Great Lakes by Tuesday with a
cold front moving through the area Monday night/Tuesday. Behind this
front...drier weather should move into the area.

As for potential of frozen or freezing precipiation for this weekend
and early next appears sfc temps will remain above
freezing areawide even at night with just plain rain far and away
the most likely precipitation type. If strength of cold airmass is
underdone however...freezing rain would occur if sfc temps dipped
below freezing across portions of northeast Missouri and west-
central Illinois.



.AVIATION:  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 536 PM CST Tue Nov 24 2015

No major changes to going forecast trends, with increasing
southerly flow and increasing low level moisture the primary
forecast concerns. Wind profiles in the latest forecast soundings
continue to support the development of a low level jet overnight,
with speeds ramping up into the 35-40kt range just below 1kft.
Therefore will continue LLWS forecast, with some minor tweaks to
timing in a few areas.

Meanwhile, north-south stratus deck developed in the low level
moisture return from southeast KS into central TX during the
afternoon. Plan view RH progs from both RUC and NAM suggest that
the leading edge of these clouds...with VFR bases...will
overspread TAF sites in the LSX CWA during the predawn and early
morning hours, with cigs in the KCOU area likely dropping below
3kft after 12z where low level moisture will be a bit deeper.

Specifics for KSTL: VFR conditions expected throughout the period,
with the development of the low level jet producing low level wind
profiles favorable for low level wind shear concerns from late
tonight into Wednesday morning. High level cirrus clouds
overnight will give way to lower end VFR ceilings by mid-morning
Wednesday...with bases 4-6kft. Primary rain threat with
approaching system will likely hold off until Thursday/Thursday



Saint Louis     41  58  52  63 /   0   5  20  40
Quincy          39  54  50  61 /   0  20  40  70
Columbia        42  58  51  63 /   5  10  30  60
Jefferson City  42  59  53  64 /   5  10  30  60
Salem           39  60  49  62 /   0   5  10  30
Farmington      39  57  50  61 /   0   5  20  40




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