Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 222147

347 PM CST SUN NOV 22 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 344 PM CST Sun Nov 22 2015

Expect another dry and cold night with clear skies.  Winds will
remain light tonight has high pressure moves off to the east.  Have
stayed on the cooler side of the temperature guidance because of the
strong radiational cooling.


.LONG TERM:  (Monday through Next Sunday)
Issued at 344 PM CST Sun Nov 22 2015

(Monday through Wednesday)

Monday and Tuesday will remain dry as weak upper ridge moves across
the area before upper flow eventually turns out of the southwest and
a weak shortwave trough moves across the area on Wednesday. This
weak trough will bring enough moisture and ascent to warrant
adding a slight chance of showers to the forecast on Wednesday.
Temperatures will moderate during this period as winds turn out of
the west and southwest. With mixing into the 925mb layer, highs
will recover into the 40s/50s by tomorrow and will be all in the
50s by Tuesday.

(Thanksgiving through Sunday)

This will be a more active period as the ECMWF and GFS both agree
that precipitation will develop over the area ahead of deep upper
over the western CONUS.  By Thanksgiving, Gulf moisture will begin
to stream northward ahead of a cold front that will move across the
area on Thursday night and early Friday.  Given that amount of
moisture moving northward and the amount of progged low level
convergence/mid level ascent, there could be a decent amount of
rainfall with this front.

Uncertainty begins to enter the forecast by next weekend as the
ECMWF shows the upper low moving into Colorado while the GFS keeps
it farther west over Idaho/Nevada/Utah.  The ECMWF is showing better
continuity with it`s solution so have followed it.  While
precipitation out of the area on Saturday, it will begin to move
back into the southern parts of Missouri and Illinois next Sunday as
large scale ascent increases ahead of the upper low in the Plains.

Temperatures during the period will go from above normal to below
normal as the cold front passes through the area and 850mb
temperatures fall from +10C to around 0C which will make allow for
some of the precipitation with this system to fall as snow behind
the cold front.



.AVIATION:  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1148 AM CST Sun Nov 22 2015

Surface ridge extending from southern portions of IL and IN
southwest into northeastern TX will move southeastward. A surface
trough over the northern Plains will move southeastward through
the taf sites late tonight with the s-swly surface wind veering
around to a wly direction after passage of the trough. Just VFR,
mid-high level cloudiness is forecast through the period.

Specifics for KSTL: Sly surface wind will veer around to a wly
direction Monday morning. VFR, mid-high level cloudiness will move
southeastward through the area this afternoon and tonight.





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