Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 151749

1249 PM CDT Tue Apr 15 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 314 AM CDT Tue Apr 15 2014

Ongoing Freeze Warning still looks on track to expire at 9am.
Despite the cold start, temperatures should climb into the 40s and
50s today. Initially NW winds expected to briefly become lgt/var
today with the passage of a surface ridge, then turn southerly
around the back side of the high.


.LONG TERM:  (Tonight through Monday)
Issued at 314 AM CDT Tue Apr 15 2014

Next forecast issue to consider is whether new frost/freeze
headlines are needed for tonight. The surface high will be located
east of the area and wind speeds will be increasing after 06-09z
due to the tightening pressure gradient ahead of a developing
surface low over NE/SD. This means that ideal radiational cooling
conditions will not be present over most of the area. Overnight
lows should be a few degrees warmer than last night (approximately
in the low to mid 30s) with dew points in the low to mid 20s.
Since low-lying areas in the southeastern CWA will probably
decouple early in the evening (under lingering influence of the
departing surface high) and not experience the increased wind
speeds after 06-09z that would interfere with frost formation, a
Frost Advisory looks appropriate for those parts of the
southeastern CWA tonight.

Look for warm and breezy conditions on Wed due to the tightening
pressure gradient ahead of a developing surface low over SD/NE.
Models do not show as much of a secondary low over the OK/TX
panhandles compared to solutions from 24hrs ago, which produces a
different set of solutions for the movement of frontal boundaries
across the central CONUS for Thu-Sat. This variability leads to
continued low confidence in the forecast for Thu-Sat.
Precipitation is possible on Thu night into Fri as a vort max
moves across the region and interacts with moisture being drawn
northward, however one area of model disagreement is exactly how
many vorticity maxima might move across the region during this
time. Models depict another system which could bring precipitation
to the area on Sunday/Sunday night.



.AVIATION:  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1237 PM CDT Tue Apr 15 2014

Dry, VFR conditions will prevail for the forecast period. West-
northwest winds today will become light/variable as the surface
ridge shifts east across the area, prior to backing to the south
and becoming strong and gusty Wednesday ahead of the next system
taking shape over the plains. The only concern tonight is the
possibility of LLWS at KUIN and KCOU as the low-level jet ramps up
during the late overnight and early morning. However, shear looks
marginal, thus have not mentioned in the TAF at this time.

Specifics for KSTL: Dry, VFR conditions expected to prevail
through the period. West-northwest winds will become light during
mid- to late afternoon as the ridge axis shifts across the area.
Overnight, the winds will begin to back to the south, increasing
in speed and becoming gusty Wednesday. Scattered diurnal cumulus
will clear tonight, with only high clouds expected on Wednesday.





STL - 27 IN 1928
COU - 25 IN 1928
UIN - 24 IN 1928
FAM - 24 IN 1928


MO...FROST ADVISORY from 1 AM to 9 AM CDT Wednesday FOR Crawford MO-
     Iron MO-Jefferson MO-Madison MO-Reynolds MO-St. Francois MO-
     Ste. Genevieve MO-Washington MO.

IL...FROST ADVISORY from 1 AM to 9 AM CDT Wednesday FOR Clinton IL-
     Marion IL-Monroe IL-Randolph IL-St. Clair IL-Washington IL.



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