Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 281149
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
649 AM CDT Fri Jul 28 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 329 AM CDT Fri Jul 28 2017

Frontal boundary is exiting forecast area as of 08z. However, models
show secondary upper level shortwave rotating around upper low that
is over Great Lakes region. It will slide southeast through region
today, possibly triggering isolated diurnal showers during the
afternoon hours. Confidence is low at this time, so just have silent
14 pops for areas along and east of Mississippi River between 20z
and 00z. Will need to keep an eye on this. Otherwise, should see
stratus begin to lift and burn off towards sunrise with scattered
diurnal cu developing. As for highs, will be a bit below normal in
the 80s.

By this evening, skies to clear out as surface ridge builds in with
drier air and cooler temps. Lows will be in the upper 50s to mid 60s.

Byrd

.LONG TERM...  (Saturday through Thursday)
Issued at 329 AM CDT Fri Jul 28 2017

Focus thru much of the period will be temps with no precip expected
until next Wed to Thurs.

Period begins with the region under NW flow as the ern trof deepens
and the upper ridge remains locked in place over the Southern
Plains. NW flow is expected to continue thru the end of the forecast
period as the upper ridge is slowly broken down by a number of s/w
that round the top of the ridge.

Despite this, mdls do show a rather slow warm up about mid week as
the sfc ridge builds south allowing light sly flow to return to the
area ahead of an approaching cdfnt.

This fnt will bring a chance of TSRA to the region. However, with
the sfc ridge extending across the srn U.S. cutting the area off
from Gulf moisture, there is some uncertainty regarding how much
moisture the fnt will have to work with. Have kept PoPs rather low
for now.

Tilly

&&

.AVIATION...  (For the 12z TAFs through 12z Saturday Morning)
Issued at 641 AM CDT Fri Jul 28 2017

North winds to persist through forecast period. As for clouds, VFR
conditions with scattered diurnal cu developing by midday, then
dissipate by early this evening with loss of daytime heating.
Isolated showers may be possible over metro area tafs, but
confidence is low at this time. So kept tafs dry for now.

SPECIFICS FOR KSTL:
North winds to persist through forecast period. As for clouds, VFR
conditions with scattered diurnal cu developing by midday, then
dissipate by early this evening with loss of daytime heating.
Isolated showers may be possible over metro area, but confidence
is low at this time. So kept tafs dry for now.

Byrd
&&

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

$$
WFO LSX


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