Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 210455
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1055 PM CST Mon Nov 20 2017

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 229 PM CST Mon Nov 20 2017

No significant weather is expected this evening. Wind gusts will
subside tonight with the loss of diurnal mixing, however the
sustained winds will likely remain near 10-15 mph overnight due to
the modest pressure gradient across the region.

A low pressure system will skirt the US/Canadian border
tonight/tomorrow and drive a cold front through the region. Parts of
northeast MO and west central IL may experience only a limited
diurnal rise in the morning hours before temperatures become nearly
steady and start falling again after fropa. Elsewhere, many
locations will experience falling temperatures during the afternoon
hours after the front has moved through the area. Model solutions
show that the front will have moved through the CWA by 00z Wed.
Although a stray sprinkle is possible tomorrow, the limited moisture
and forcing suggest that widespread measurable precipitation is
unlikely. The better opportunity for precipitation will be farther
north and east where there is deeper moisture and move overlap with
upper forcing for ascent.

Kanofsky

.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 229 PM CST Mon Nov 20 2017

Roller coaster temperatures to be the main theme through the
extended forecast period. Surface ridge builds into region Tuesday
night with decent CAA. So with clear skies and light winds, will see
lows in the low to mid 20s.  Wednesday will be the coldest day this
week with highs only in the upper 30s to mid 40s.

Surface ridge to begin moving off to the east Wednesday night so
will see southerly winds return to the area briefly before next cold
front slides through on Thanksgiving. Fortunately this frontal
passage should be a dry one, as main energy and moisture remain to
the north of us over the Great Lakes region. Will still see warmer
temps on Thursday, in the upper 40s to mid 50s.

Even warmer temps expected on Friday with highs in the mid 50s to
mid 60s, 5 to 10 degrees above normal for this time of year. Then
next in series of weak cold fronts to slide through region Friday
night. Little or no precipitation is expected with this one as well
with main energy to our north once again. Despite dry passage with
this front, system to continue digging to our east with deep trof
aloft and upper ridge to our west. So will see decent surface ridge
build in with temps dipping down into the 40s everywhere by Sunday.
Then pattern continues with moderating temps by next Monday.

Byrd

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1050 PM CST Mon Nov 20 2017

Dry and VFR conditions are expected through the period. LLWS will
continue through mid morning on Tuesday as a south southwesterly
low level jet has developed over the area. A cold front will move
southeast across the area on Tuesday causing the wind to shift
from southwest to northwest.

SPECIFICS FOR KSTL:

Dry and VFR conditions are expected through the period. LLWS will
continue through 15Z. A cold front will move through the terminal
around 19Z causing winds to shift out of the northwest.

Britt

&&

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

$$

WFO LSX



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