Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 192348
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
548 PM CST Sun Nov 19 2017

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 109 PM CST Sun Nov 19 2017

No significant weather is expected through late Monday afternoon.
Initially northwest winds will become westerly to southwesterly
after a surface high pressure center has moved from the southern
plains into the southeastern CONUS. The change in wind direction
will bring a warmer air mass back into MO/IL, and highs on Monday
are expected to be in the mid-50s to lower 60s.

Kanofsky

.LONG TERM...  (Monday Night through Next Sunday)
Issued at 109 PM CST Sun Nov 19 2017

Although a couple of PV anomalies will move across the region over
the next several days, it will be difficult to produce widespread
precipitation due to a dry air mass. At best, some of the upper
disturbances may produce increased mid/high clouds.

Temperature swings are expected over the next several days due to
frontal passages, but no widespread precipitation is expected at
this time due to limited moisture. The first of these fronts will
be a cold front which is expected to move across MO/IL on Monday
night and Tuesday. Models solutions indicate that the colder air
lags the initial wind shift/pressure trough. Depending on the
speed of the colder air, some parts of MO/IL could experience
falling temperatures during the day on Tuesday. The tightening
pressure gradient and stronger wind speeds aloft will also bring
windy conditions to the region. Lows on Tuesday night will
probably be in the 20s within the post-frontal air mass, which
will be nearly 20 degrees cooler compared to the previous night. A
surface high pressure center settles across the region for
Wed/Thu before the influence of a developing low pressure system
over Canada brings a warmer air mass back into the region on
Friday ahead of another cold front which is forecast to move
through the region on Fri night/Sat.

Kanofsky

&&

.AVIATION...  (For the 00z TAFs through 00z Monday Evening)
Issued at 541 PM CST Sun Nov 19 2017

VFR flight conditions will continue through the forecast period
with bouts of high clouds streaming across the area. The main
element of concern will be wind. Surface winds tonight will
becoming light southerly as the surface high moves to the east.
During the overnight hours a LLJ will develop based around 1000 ft
AGL from eastern KS across northern MO into northwest IL. This LLJ
will bring LLWS conditions overnight in Monday morning to both
KCOU and KUIN. After 15z, vertical mixing should bring an end to
the LLWS and increasing and gusty S-SW surface winds will
commence.

SPECIFICS FOR KSTL:

VFR flight conditions will continue through the forecast period
with bouts of high clouds streaming across the area. Surface
winds tonight will becoming light southerly as the surface high
moves to the east. After 15z, vertical mixing should bring increasing
and gusty S-SW surface winds.

Glass

&&

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

$$

WFO LSX


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