Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 231742

1242 PM CDT Thu Oct 23 2014

.SHORT TERM:  (Through This Afternoon)
Issued at 313 AM CDT Thu Oct 23 2014

Broad N-S band of showers and isolated thunderstorms ahead of plains
shortwave currently stretch from western IA, through nw MO, into se
KS, and the primary forecast question for today is how far east this
rain will get.   Strong ridging with very dry low level air remains
locked in place from the Great Lakes to the Ohio Valley by storm
system working its way up the east coast, and this will certainly
inhibit any substantial increase in lower tropospheric moisture.
Believe that the combination of shortwave energy, moisture
advection, and isentropic ascent will cause upstream showers to work
work into our far nw counties this morning, with this precip then
struggling eastward during the day and "withering on the vine" from
central MO into west central IL during the afternoon hours as
shortwave outruns the limited low level moisture return and
encounters much drier air.  Still working on fine-tuning the
details, but at this time planning to limit any mention of precip to
areas northwest of a Cuba-St Louis-Hillsboro line, with highest PoPs
just east of Kirksville.


.LONG TERM:  (Tonight through Wednesday)
Issued at 313 AM CDT Thu Oct 23 2014

(Tonight through Saturday)

With no precip anticipated, focus thru this period will be temps.

Mdls are in good agreement with upper trof moving E of the region
overnight and swly flow at the sfc returning ahead of the next
cdfnt. This cdfnt is progd to push thru Sat morning, which may
require adjustments to temps on Sat with future updates.

With clouds expected to clear late tonight, have trended twd the
cooler guidance for tonight. With the thermal ridge advecting into
the region for Fri, have trended twd the warmer guidance. Similar
trends for Fri night with swly flow continuing overnight. Sat has
some forecast challenge with fropa expected in the morning. With
full insolation expected, have trended twd the warmer guidance even
with a nwly flow.

(Sunday through Wednesday)

Focus turns to precip chances on Tues.

23/00z mdls are in generally good agreement thru Tues morning, tho
the GEM is faster with the upper trof ejecting into the Plains. Have
focused PoPs on Mon night and Tues when the ECMWF/GFS have come into
better agreement. However, the 00z solns are somewhat different from
the prev 12z solns. Therefore, have still kept PoPs on the lower
side for now until a persistent signal is given.



.AVIATION:  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1238 PM CDT Thu Oct 23 2014

Rain showers having a real tough time moving east due to dry air
in lower levels. That being said, I can`t rule out a sprinkle or
brief shower at KCOU or KUIN this afternoon. Otherwise, low level
moisture will be on the increase later this evening and overnight
as southerly flow continues. This should lead to some MVFR
conditions in both the ceiling and visibility category overnight.

Specifics for KSTL:

VFR conditions expected until later tonight when MVFR ceiling will
develop and fog may reduce visibility to 5SM. Scattering of cloud
cover is expected on Friday with a continued light southerly wind.





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