Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 271815
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1215 PM CST Sun Nov 27 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 324 AM CST Sun Nov 27 2016

Stratus associated with dense fog that was over southwestern MO will
continue to lift northeast through forecast area this morning. As
winds pickup today, will eventually see this stratus lift and
scatter out. In the meantime as deepening low over central plains
begins to lift northeast today, will see increasing mid and high
clouds. Precipitation chances with this system will gradually
increase from west to east with best chances from late this
afternoon through tonight. Not a lot of instability with this
system, so most of precipitation to be in the form of showers. Weak
CAPES up to about 500 J/kg could trigger isolated thunderstorms. So
kept mention of isolated thunder in for this evening.

Otherwise, despite warm southerly winds today, the increasing clouds
will dampen the warm up a bit with highs in the 50s. With main cold
front not moving through til Tuesday, lows tonight will remain
rather mild for this time of year, in the mid 40s to low 50s.

Byrd

.LONG TERM...  (Monday through Saturday)
Issued at 324 AM CST Sun Nov 27 2016

Main focus continues to be precip chances on Mon thru Mon night.
Within this period, mdls are in fairly good agreement with the
heaviest precip, and best chances, being across the srn and ern
portions of the CWA on Mon with the precip exiting the area Mon
evening. Have maintained low chances for TS on Mon as the trof swings
thru the area, tho threat will remain limited.

With questions on cloud cover and precip during the day on Mon and
given a larger spread in MOS guidance, have made only small changes
to temp forecast for Mon. With more insolation expected on Tues,
have trended twd the warmer guidance.

After fropa late Tues, the region remains under CAA thru the
remainder of the forecast period as the low slowly moves ewd. Mdls
suggest the sfc ridge building into the region late in the period.
This is expected to result in a prolonged dry period with temps near
seasonal average.

Tilly

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1150 AM CST Sun Nov 27 2016

Strong storm system winding up in the western Great Plains will
spread showers and an a few isolated thunderstorms across the
area from west to east this afternoon into tonight. VFR conditions
this afternoon with patches of IFR and MVFR will lower to MVFR
this evening and tonight as the precipitation overspreads the
area. The low level wind field will be very strong ahead of this
system with a 50+kt southerly low level jet so low level wind
shear will be an issue tonight and early tomorrow morning. Low MVFR
conditions will continue to prevail Monday morning with some IFR
ceilings possibly developing along and east of the Mississippi
River.

SPECIFICS FOR KSTL:

VFR conditions are expected to prevail this afternoon. There may
be a few sprinkles or brief showers before 00Z, but the main band
of showers will likely hold off until after 03Z this evening.
Think chances for thunder at Lambert are minimal tonight. The low
level jet really increases sharply this evening, and low level
wind shear is likely even though the wind will be gusty at the
surface. Ceiling will likely fall to MVFR with the rain and stay
down through the remainder of the period.

Carney

&&

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

$$

WFO LSX



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