Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 181709

1209 PM CDT Fri Apr 18 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 328 AM CDT Fri Apr 18 2014

A tranquil Friday looks to be on tap, as the weakening cold front
continues moving southeast out of our area this morning, with any
accompanying shower activity already southeast of our area over
the Missouri bootheel. Skies over central and northeast Missouri
as well as west central Illinois are clear, and expect the
clearing trend to continue from north to south through the morning
hours for the remainder of the forecast area. Rising heights at
500mb will overspread the area today, as a ridge begins to develop
over the middle Mississippi Valley in the wake of the departing
trough. Temperatures today will climb to the mid 60s north to
around 70 for the St. Louis metro area and southern zones, fairly
close to, or even slightly above normal for this time of year.


.LONG TERM:  (Tonight through Thursday)
Issued at 328 AM CDT Fri Apr 18 2014

A big warm up is on the way for the weekend as a ridge amplifies
over the middle Mississippi Valley and southerly flow returns to
the region. Temperatures across the area should have no trouble
reaching the mid 70s on Saturday, and mid to upper 70s Sunday,
with some locations perhaps flirting with the 80 degree mark.
However, by Sunday evening, the 500mb ridge axis will shift east
of the area and flatten slightly, allowing for quasi-zonal to
southwesterly flow over the area late Sunday and into Monday. A
shortwave is progged to move into western Missouri late on Sunday,
and current feeling is that instability will be sufficient for some
thunderstorms to occur, given the warm temperatures and ample
moisture ahead of the system thanks to several days of return
flow. Models have slowed down the progression of this feature
somewhat, thus it looks like this initial shortwave and associated
precipitation will move east across Missouri Sunday night,
leaving much of the day Sunday dry across the forecast area. On
Monday, a reinforcing trough and cold front will move through the
area in the wake of the shortwave, continuing the chance for
showers and thunderstorms through the day on Monday and Monday
night. Both the GFS and ECMWF are in agreement that the front and
associated precipitation will be south of the forecast area by 12Z
Tuesday. Temperatures are still expected to remain near or
slightly above normal.

Beyond next Tuesday, expect another warm up across the area, as
the trough shifts east and deepens over the eastern CONUS and
ridging once again takes place over the middle Mississippi Valley.
Southerly flow will continue to increase Wednesday and Thursday,
with a chance of thunderstorms across the area on Wednesday night
and Thursday in part due to the strengthening warm advection.
Temperatures during this time frame are expected to be in the
middle to upper 70s, continuing the above normal trend. An
intensifying low pressure system over the northern plains is
anticipated to impact the area late next week, though model
agreement is currently lacking in its progression. Thus, feel that
continued warming temperatures and broad brushed chance PoPs
through Thursday are sufficient at this time.



.AVIATION:  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1207 PM CDT Fri Apr 18 2014

High pressure will dominate the region resulting in clear skies
and light winds. Some radiational fog will be possible early
Saturday morning at KSUS where the wind will likely be calm. VFR
conditions will continue on Saturday with increasing southeasterly

Specifics for KSTL:

High pressure will dominate the region resulting in clear skies
and light winds. VFR conditions will continue on Saturday with
increasing southeasterly winds.





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