Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 260907
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
407 AM CDT Tue Sep 26 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 406 AM CDT Tue Sep 26 2017

An upper level trough over the northern Plains will move eastward
into the northern portion of the Great Lakes region tonight, and
send a cold front currently extending from northwestern WI southwest
into central OK southeastward through our forecast area today and
this evening.  Scattered showers and a few thunderstorms can be
expected along and just behind this front today into this evening.
Going with mainly just slight chance pops across northeast and
central MO and west central IL with the best upper level forcing
remaining north of our forecast area and low level moisture limited
as the Gulf is cut off. The HRRR model keeps most of the
precipitation associated with the front north and west of our
forecast area this morning with widely scattered convection
developing this afternoon, enhanced by diurnal heating and
instability.  It appears that the coverage of the precipitation will
become more isolated later this evening with any remaining showers
of only light intensity.  Unseasonably warm temperatures are
expected again today, especially across east central and southeast
MO and southwest IL ahead of the cold front.  Cooler temperatures,
closer to seasonal normals can be expected across parts of northeast
MO today, and northeast and central MO and west central IL tonight.

GKS


.LONG TERM...  (Wednesday through Monday)
Issued at 406 AM CDT Tue Sep 26 2017

A few post-frontal showers are possible on Wednesday, mainly across
portions of central and southeastern Missouri. Otherwise, much
cooler temperatures will be the main story. Near to slightly below
normal temperatures, with unfortunately a continued dry trend, is
likely then for the rest of the work week and this upcoming weekend.
Expect high temperatures mainly in the 70s Thursday through Sunday,
with lows each morning in the 40s and 50s. Model guidance for
temperatures seemed reasonable for the most part, but did lower
minimum temperatures for Saturday and Sunday morning a couple of
degrees, focusing predominantly on the favored terrain of the
eastern Ozarks. A moderating trend will begin on Monday as 850-hPa
temperatures rebound into the mid teens. A weak Pacific cold front
will also approach portions of northeastern Missouri on Monday
bringing a chance of showers.


Gosselin


&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1143 PM CDT Mon Sep 25 2017

Frontal boundary will be slow to move through region. For now VFR
conditions with light south winds which will begin to veer to the
southwest by mid morning. Front will move into KCOU and KUIN by
19z, then finally into the STL metro area by 00z Wed, with winds
veering to the west to northwest. As for precipitation chances,
moisture remains limited so left tafs dry for now. Will just see
low end VFR cigs as front moves through.

SPECIFICS FOR KSTL:
Frontal boundary will be slow to move through region. For now VFR
conditions with light south winds which will begin to veer to the
southwest by 18z. Front will move into STL metro area by 00z Wed,
with winds veering to the west then northwest. As for precipitation
chances, moisture remains limited so left tafs dry for now. Will
just see low end VFR cigs as front moves through.

Byrd

&&

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

$$

WFO LSX



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