Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 201820

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1220 PM CST Fri Jan 20 2017

Issued at 1253 AM CST Fri Jan 20 2017

Unseasonably warm temperatures overnight with lows only falling
into the lower and middle 40s. This is 20 to 25 degrees above
normal! If you go by climatology, this should be the coldest time
of the year with average HIGH temperatures in the upper 30s to
around 40 degrees. Another week and our average highs start
climbing back into the lower 40s!



.SHORT TERM... (Through Saturday)
Issued at 1253 AM CST Fri Jan 20 2017

Widespread dense fog blankets the region this morning and much of
the short term model guidance along with climatology suggest that
visibility will not improve until 16Z, so have extended the Dense
Fog Advisory through 10 a.m.

Fog and stratus will try to lift this afternoon, with perhaps a
few peaks of sunshine appearing across the eastern Ozarks by
sunset. This will once again severely limit our diurnal
temperature rise. Have adjusted high temperatures down a couple
categories for today.

Skies will try to clear on Saturday and this forecast assumes that
they do with sunshine for most of the afternoon. With this in mind
have kept high temperatures ridiculously warm for the third
Saturday in January with most locals reaching into the 60s. It
doesn`t appear that any records are obtainable, but certainly the
pick day of the weekend (see climate section below).


.LONG TERM... (Saturday Night through Thursday)
Issued at 1253 AM CST Fri Jan 20 2017

Next piece of energy expected to develop into a cutoff low and
move south-southeast from the southern Plains to the Gulf Coast
the second half of the weekend. Have maintained a chance of rain
and isolated thunderstorms for the southern half of the CWA
Saturday night and Sunday given the proximity of the storm system.
Increasing cloud cover Saturday night and lingering through Sunday
night should once again but a cap on the diurnal temperature curve
while temperatures remain above normal.

Upper level ridging in the wake of that storm system should bring
a quiet period of weather to the region Monday and Tuesday with
above normal temperatures.

A pattern shift appears to be in the offing for the middle to end
of next week as the main trough of low pressure that has been
anchored across the west coast will shift east across the Midwest
and allow a new trof of low pressure to setup across the eastern
CONUS by next weekend. With this pattern change there will be a
chance of some light precipitation, more clouds (yay) and
temperatures returning to readings more typical for winter.



.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1146 AM CST Fri Jan 20 2017

Visibilities have improved quicker than prev anticipated. However,
cigs are expected to be slower to improve. Expect cigs to improve
this evening and overnight. Have added LLWS late tonight into Sat
morning. Expect more clouds to move into the region Sat, but
expect VFR cigs.



Issued at 1253 AM CST Fri Jan 20 2017

January 21st Record High Information

St. Louis, Missouri  STL  75  (1986)
Columbia, Missouri   COU  73  (1957)
Quincy, Illinois     UIN  69  (1957)


MO...Dense Fog Advisory until 1 PM CST this afternoon for Audrain MO-
     Knox MO-Lewis MO-Marion MO-Monroe MO-Pike MO-Ralls MO-
     Shelby MO.

IL...Dense Fog Advisory until 1 PM CST this afternoon for Adams IL-
     Brown IL-Pike IL.



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