Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 181601

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
1101 AM CDT SUN SEP 18 2016

Issued at 1101 AM CDT Sun Sep 18 2016

Morning fog did burn off as expected.  Area of debris cloudiness
associated with MCS now moving across Arkansas should move off to
the east by early this afternoon leaving mainly sunny skies across
the area. RAP soundings are showing mixing up to 900-850mb this
afternoon which should result in highs in the lower-mid 80s. Still
may be some isolated showers over the far southern part of the
eastern Ozarks where there surface observations is showing some
weak convergence, but coverage should be limited.



.SHORT TERM...  (Through Late This Afternoon)
Issued at 301 AM CDT Sun Sep 18 2016

With surface ridge over region, winds are light and plenty of low
level moisture. So patchy fog developing early this morning reducing
visibilities to less than a mile at times, mainly for areas along
and south of I-70. Conditions to improve by mid morning with partly
to mostly sunny skies and temps warming up into the low 80s. Some
activity to develop just south of forecast area on periphery of
surface ridge by this afternoon that could move northeast into
forecast area, so added slight chance pops to far southern portions.


.LONG TERM...  (Tonight through Saturday)
Issued at 301 AM CDT Sun Sep 18 2016

(Tonight - Tuesday)

Period continues to look dry and warm. Sfc ridge will continue to
build ewd tonight as the upper trof pushes east and upper flow
becomes wly. Upper ridge will build into the region thru Tues, which
shud suppress precip chances. However, an upper trof will move
across srn Canada and the Northern Plains into the Great Lakes Mon
into Mon night. The associated sfc cdfnt is progd to drop into srn
IA and central IL.

With very strong low level WAA ahead of the fnt, much of the area
shud remain capped with warm nose centered around 800mb. However,
given the proximity of what shud be ongoing convection Mon afternoon
and eve as well as potential for elevated convection later in the
night, have kept low PoPs for nrn portions of the CWA.

As for temps, for tonight, have made only minor changes to the prev
forecast. While winds will become sly, low lying areas across the
ern Ozarks shud still decouple allowing temps to drop into the 50s.
Given the warm 850 mb temps between 18 and 22C on both Mon and Tues,
have trended aoa the warmest guidance both days. More uncertainty
exists on Tues for nrn portions of the CWA as the cdfnt pushes swd.

(Wednesday - Saturday)

The CWA is still expected to remain on the nrn edge of rather strong
upper ridge.  This will allow warm temps to continue thru much of
the period with little chance for precip until next weekend.

Based on heights across the region, going forecast is probably too
cool, but have kept a persistence forecast going for now. More
questions remain for temps on Sat ahead of an approaching closed low
system. Believe mdls prog this system moving ewd too quickly as is
generally the case for this type of system with the GEFS mean
suggesting a more likely soln. However, will trend closer to climo
for temps on Sat for now.

Have low chance PoPs for Sat as the cdfnt approaches the region for
now, although, as mentioned above is probably on the fast side.



.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 703 AM CDT Sun Sep 18 2016

Patchy fog affecting taf sites through 13z. Then will see VFR
conditions with light south winds becoming southeasterly by this

Patchy fog mainly affecting KSUS and KCPS through 13z. Then will
see VFR conditions with light south winds becoming southeasterly
by this evening at all metro area taf sites.



Issued at 301 AM CDT Sun Sep 18 2016

Record highs for 19 and 20 September

     Date    Record     Year
UIN   19       95       1972
      20       95       1940

COU   19       94       2000
      20       98       1893

STL   19       96       1955
      20       96       1940




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