Area Forecast Discussion
Issued by NWS St. Louis, MO

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567
FXUS63 KLSX 260005
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
705 PM CDT Mon Sep 25 2017

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 232 PM CDT Mon Sep 25 2017

Little change the next 12 hours as a cold front slowly makes it way
across the area. Light southerly winds overnight with perhaps some
mid or high clouds moving into the area. The front should be on a
Columbia to Quincy, IL line about 2pm - 3pm. Models not creating
much lift ahead of the front with model CAPE values barely cracking
500, and this is along and behind the front. 20% to 30% chances from
central to northeast MO into west central IL for Tuesday afternoon
look good. Until more clouds move in Tuesday afternoon, temperatures
will remain well above normal.  Plenty of 80s and 90s but high
temperature records look safe.

JPK

.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 232 PM CDT Mon Sep 25 2017

Upper pattern will be transitioning from southwest to northwest flow
mid-late this week as upper trough currently over western Canada
digs southeastward into the eastern CONUS.  There will be some weak
post-frontal forcing that will bring some scattered showers to the
area on Tuesday night and Wednesday morning.  After that, mainly dry
weather is expected through the upcoming weekend as the Gulf will
get cut off and any significant storm systems will stay north and
west of the area.  By early next week, the GFS is consistent with
showing southwesterly upper flow developing over the area with low
level moisture return.  This would allow for some isolated showers
early next week.

Global models are forecasting 850mb temperatures to fall into the 8-
10C range, so highs will be near normal late this week and this
weekend. Lows in outlying areas will likely fall into the 40s over
the weekend.

Britt
&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 657 PM CDT Mon Sep 25 2017

Light south winds to persist ahead of next frontal boundary. Cold
front to begin moving through forecast area during the day on
Tuesday. So winds to veer to the southwest then west to northwest
with frontal passage. Moisture will be limited so precipitation
chances limited with frontal passage, kept tafs dry for now.

SPECIFICS FOR KSTL:
Light south winds to persist ahead of next frontal boundary. Cold
front to begin moving through forecast area during the day on
Tuesday. So winds to veer to the southwest then west to northwest
by 23z Tuesday. Moisture will be limited so precipitation chances
limited with frontal passage, kept taf dry for now.

Byrd
&&

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

$$
WFO LSX



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