Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 071714

1214 PM CDT WED OCT 7 2015

.SHORT TERM: (Through Tonight)
Issued at 257 AM CDT Wed Oct 7 2015

Main question for today will be temps.

With weak steering winds thru 600 mb, current cloud cover is
expected to slowly drift swd today. FG developing across srn
portions of the CWA is also expected to lift to form some cloud
cover this morning. With more cloud cover expected today, have
lower temps slightly compared to prev forecast. However, even
brief periods of sun shud allow temps to jump quickly. As for
tonight, with light winds, have trended cooler across srn portions
of the CWA, but kept a warmer trend across wrn and nrn areas where
winds will become sly with more cloud cover tonight ahead of the
approaching cdfnt.


.LONG TERM: (Thursday through Tuesday)
Issued at 257 AM CDT Wed Oct 7 2015

Focus quickly turns to precip chances associated with the fnt on
Thurs night and Fri. Latest mdl guidance has continued to slow
fropa, but mdl solns remain in good agreement.

Mdls continue to show the sfc ridge building ewd as the low
approaches. The region never really becomes open to the Gulf ahead
of the approaching cdfnt and low system. This shud limit the
amount of moisture available for storms. CAPE is also somewhat
limited ahead of the fnt. Due to the limited moisture and the
performance of the last fnt to move thru the region, have been
hesitant to forecast PoPs above 50 percent. Still believe SHRA
will develop with isod to widely sct TS, but coverage is not
currently anticipated to be great.

Large sfc ridge builds into the area, but sly flow is back by Sat
allowing warmer temps for most of the weekend and into next week.
Timing of the next fnt, sometime on Mon into Tues, is uncertain
due to differences among guidance. However, expect fropa to remain
dry due to even less moisture available than with the fropa on
Thurs and Fri.



.AVIATION:  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1149 AM CDT Wed Oct 7 2015

Between the persistent stratocumulus cloud mass between COU and
the St Louis metro area and the diurnal cumulus clouds developing
on the periphery of the stratocumulus cloud deck it appears that
a cloud ceiling around 3500-4500 feet should be the general consensus
for the taf sites this afternoon. Much of the low level cloud deck
may scatter out this evening with the loss of daytime heating.
Mid-high level cloudiness should spread into the area tonight
which should help to limit fog potential. The NAM model MOS
guidance is likely too robust on its forecast of stratus and fog
late tonight/early Thursday morning. Light surface winds will
become swly by late Thursday morning as the weak surface ridge
over our area this afternoon shifts southeast of the region and a
cold front approaches.

Specifics for KSTL: Low level, VFR cloud ceiling should scatter
out early this evening with mainly mid-high level clouds tonight
and Thursday. Light surface wind will become swly by late Thursday
morning, increasing to 8-9 kts Thursday afternoon.





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