Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 192245
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
545 PM CDT Mon Jun 19 2017

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 322 PM CDT Mon Jun 19 2017

Ongoing sct SHRA with isod TS will continue to move sewd late this
afternoon and are expected to dissipate with sunset. Otherwise,
tonight is expected to remain dry.

Clouds will also dissipate with sunset leaving tonight clear. The
sfc ridge will slowly build ewd across the srn portions of the CWA
overnight. With the weak sfc trof dropping thru the area associated
with the s/w generating the SHRA, a weak and messy sfc wind flow is
expected tonight. Do not see a great setup for fog development
tonight. However, with lighter winds across srn portions of the CWA,
fog is again possible in low lying areas.

Expect tomorrow to be slightly warmer compared to today as sfc winds
become more wly to swly despite NW flow aloft. The 850mb thermal
ridge will also build into the region with temps 2 to 4C warmer.
Have therefore trended aoa the warmer guidance on Tues.

An upper trof and associated sfc cdfnt will drop into nrn portions
of the CWA late Tues afternoon. This fnt shud help spawn isod to sct
TSRA along and just ahead of the fnt during the late afternoon
hours. These shud linger into the evening hours.

Tilly

.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 322 PM CDT Mon Jun 19 2017

Northwest flow aloft to persist with weak frontal boundary sinking
south towards forecast area Tuesday night, stalling out along
Iowa/Missouri border. 12z models have some lingering showers/storms
during the evening hours over northeast MO/west central IL, so kept
slight chance pops going in this area. Otherwise, dry and above
normal temperatures to persist through Wednesday.

By Wednesday night, upper level flow becomes more zonal with next
system approaching region. Will see increasing chances of showers
and storms towards daybreak on Thursday for northern portions of
forecast area through Thursday evening.

By Friday, surface ridge weakens allowing boundary to sink south
into forecast area. In the meantime, extended models are hinting at
remnants of a possible tropical cyclone to lift northeastward
towards bootheel region during this period as well. For now have
kept pops in chance category with best chances of rain Friday/Friday
night.

As system slowly exits region, will see below normal temps beginning
Saturday and persist into early next week. Dry weather to return to
region by Sunday afternoon.

Byrd

&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 541 PM CDT Mon Jun 19 2017

Scattered showers and isolated thunderstorms currently over the
area are expected to dissipate by sunset. It appears that there is
a low risk that they will affect any of the terminals after 00Z.
Otherwise dry and VFR conditions are expected through the period.
Winds are expected to become light overnight

SPECIFICS FOR KSTL: Dry and VFR conditions are expected through
the period. Winds are expected to turn light out of the west
overnight.

Britt

&&

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

$$

WFO LSX



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