Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 011734

1234 PM CDT THU OCT 1 2015

Issued at 1134 AM CDT Thu Oct 1 2015

Forecast for this afternoon looks good with some diurnal cu
developing over Illinois as well as east central and southeast
Missouri. Mixing will allow for some wind gusts in the 20-25 mph
range this afternoon. Still expect highs to reach the upper 60s in
most areas.



.SHORT TERM:  (Through Late This Afternoon)
Issued at 245 AM CDT Thu Oct 1 2015

Early this morning, northwest flow aloft prevails with an upper
level disturbance over southern IL, slowly moving away from our
region to the southeast.  All of what this disturbance is producing
is all on its eastern flank (southeast IL) with clouds and some
evidence of a few sprinkles as well.  At the surface, Canadian high
pressure is steadily building and settling in to our region, with
northeast surface winds bringing more autumnlike air, as temp
readings dip into the 40s and low 50s.  Otherwise, the sky was clear
across much of our region other than a few clouds edging the far
eastern portion around Salem, IL.

Northwest flow aloft will carry the upper level disturbance away
from our region, and surface high pressure will dominate,
resulting in NE winds and a dry atmospheric column.  Despite a lot
of clouds existing just to the east and there is flow aloft from the
east currently, this will all change over the next few hours as the
upper level disturbance pulls out and will limit how far west these
clouds will be able to go this morning.  Otherwise, the only clouds
expected today are some scattered diurnal cumuliform that will
probably initially begin east of the MS river and expand some to
west of the river late in the day before dissipating by evening.

Prefer the higher MOS values for max temps today, considering the
high levels of sunshine, and this will give us readings a few
degrees below persistence, or 65 to 70F.


.LONG TERM:  (Tonight through Wednesday)
Issued at 357 AM CDT Thu Oct 1 2015

Cool and dry weather pattern will continue tonight with a deep upper
level trough just east of the forecast area and persistent strong
surface ridging extending from the northern Plains and Great Lakes
region south into MO.  The models were forecasting 850 mb
temperatures tonight of only around 7-9 degrees C across our
forecast area.  Low level ely flow should bring increasing
cloudiness into our area Friday night on the backside of the mid-
upper level low and associated inverted surface trough over the Gulf
Coast region.  Light rain or showers may retrograde westward into
parts of southwest IL Friday night through Saturday night, although
the NAM model appears to shift the rain shield too far west and
prefer the QPF forecast of the GFS and ECMWF models.  Cloud cover on
Saturday should lead to relatively cool high temperatures, about 10
degrees below normal for early October, although the NAM model may
be too low on the height of the cloud ceiling and hence too cold on
its forecast highs.  A warming trend can be expected for the start
of the next work week as an upper level ridge builds into our
region.  Also the surface/low level winds will become southerly
beginning on Tuesday as a surface ridge shifts east of the region.
The chance of showers will return to much of our area on Wednesday
and Wednesday night as the upper level ridge flattens allowing a
cold front to sag southward into our area.



.AVIATION:  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1234 PM CDT Thu Oct 1 2015

Scattered to broken low VFR ceilings are expected this afternoon
before they dissipate with the loss of daytime heating. Northeast
winds will also gust to around 20 knots this afternoon before
mixing ends early this evening. Then expect mainly clear skies and
winds in the 5-10KT range through the night before scattered-
broken VFR ceilings redevelop during the mid-late morning on
Friday with gusty northeast winds.

Specifics for KSTL: Expect scattered or possibly broken VFR
ceilings this afternoon with northeast crosswinds. The winds and
clouds will diminish tonight with loss of daytime heating.
Expected low VFR broken ceiling to develop by late morning with
northeast crosswinds.





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