Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 150420
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1120 PM CDT Tue Apr 14 2015

.SHORT TERM:  (Through Late Tonight)
Issued at 319 PM CDT Tue Apr 14 2015

May have a few sprinkles early this evening from mid level clouds,
but the better potential for measurable rain should hold off until
later this evening and overnight as the upper level trough with
embedded shortwaves moves from the southern Plains northeastward
into MO by 12Z Wednesday.  As the low level winds veer around to a
southeasterly direction low level moisture will spread back
northward into MO, mainly west of the Mississippi River on the
southwestern periphery of the 850 mb ridge.  Showers should move
into portions of southeast and central MO later this evening, then
shift northward into portions of northeast MO towards morning.  With
more mid level moisture and cloudiness moving back into our forecast
area went on the warmer side of the MOS guidance for low
temperatures tonight.

GKS

.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 319 PM CDT Tue Apr 14 2015

(Wednesday through Friday)

Main focus thru this period will be RA chances.

Upper low over KS is helping generate RA across KS and into OK. This
low will continue to open and lift nwd thru Wed. Some question as to
how much coverage will be left tomorrow and into the eve hrs. Still
believe coverage will be at least sct across portions of the area.
However, exactly where those areas will be remains somewhat
uncertain.

Focus quickly turns to RA chances on Fri. Mdls continue to differ
greatly with the lee low ejecting into the Plains some time late
this week. The GFS continues faster with a similar soln as
yesterday, which does lend some confidence in it, esp as the GEFS
mean is trending faster than the ECMWF. However, as this is still
soln is still a fast outlier, have trended away from it and twd the
ECMWF. The GEM is even slower than the ECMWF and have largely
ignored this soln.

As for temps, with RA expected tomorrow, have trended twd the cooler
guidance. With less clouds expected Thurs have trended warmer, but
then twd cooler guidance again on Fri with more RA/clouds possible.

(Saturday through Tuesday)

Closed low will try and finally make progress eastward this weekend.
As mentioned above...slower ECMWF/GEM are preferred solutions. Chances
of showers with an embedded thunderstorm or two are possible through
Monday...with the best chance (40-50 PoPs) on Sunday as ECMWF/GEM
solutions eject system out into mid-Mississippi Valley. Behind this
system...cooler and drier weather is expected Monday night and Tuesday
with temperatures dipping back below normal as 850-hPa temps slide
into the single digits above zero Celcius.

Tilly/Gosselin

&&

.AVIATION:  (For the 06z TAFs through 06z Wednesday Night)
Issued at 1111 PM CDT Tue Apr 14 2015

VFR flight conditions should continue to prevail at the TAF sites
with predominantly mid-high clouds tonight lowering to 4000-8000 ft
on Wednesday. MVFR cigs may move into central and east central MO
after 00z/16th but confidence is not great enough to mention at
this time.

Central MO/KCOU is the only terminal with confidence to mention
any light rain. There might be some additional light rain between
06-08z otherwise the next time frame with potential is roughly
17-21z. Elsewhere some light rain showers may impact the St.
Louis area terminals in the afternoon but confidence is too low to
mention.

Specifics for KSTL:

VFR flight conditions are expected to prevail with predominantly
mid-high clouds tonight lowering to 4000-5000 ft on Wednesday
afternoon. Scattered light rain showers may impact the terminal
on Wedneday afternoon, and MVFR cigs might move into the terminal
after 00z/16th, however confidence is not great enough for either
element to include in the forecast at this time.

Glass

&&

.LSX WATCHES/WARNINGS/ADVISORIES:
MO...NONE.
IL...NONE.
&&

$$

WFO LSX





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