Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 020824
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
324 AM CDT Sat May 2 2015

.SHORT TERM: (Today and Tonight)
Issued at 310 AM CDT Sat May 2 2015

The flow aloft over the next 36 hours will generally be progressive
as the upper trof just off the Atlantic Coast departs eastward
while the flat ridge aloft currently centered in the vicinity of
the Rockies shifts into the Nation`s center. West-northwest flow
aloft will persist through our region and this will result in a
steady stream of embedded weak low-amplitude disturbances. As a
result, clouds will be more plentiful today and tonight although
there will be periodic thinning and dissipation with the passage
of these features. The best chance of any precipitation today
would be some spotty showers across northeast MO and west central
IL. Despite the clouds, the retreat of the low-level anticyclone
will bring increasing southerly flow and improved warm advection
although deeper moisture is still in the waiting. Temperatures
will respond accordingly with highs well into the 70s, possibly
touching 80 in a few spots in central and east central MO. A
broad southwesterly LLJ will produce a good warm advection and
improved moisture return tonight, generally focused from Iowa into
the upper MS Valley. Northeast MO and west central IL will be on
the eastern periphery of the lift and moisture which is sufficient
to merit low pops.

Glass

.LONG TERM: (Sunday through Friday)
Issued at 310 AM CDT Sat May 2 2015

The aforementioned flat ridge aloft will build and shift eastward
through the MS valley Sunday into Monday. Continued low level warm
advection/rising low level temperatures will produce highs around
10 degrees above average. While Sunday looks predominately dry, a
southward moving west-east oriented cold front will move into
southern Iowa late Sunday night and settle across northern MO into
central IL on Monday. Improved low level moisture and steepening
mid level lapse rates will result in an increasing unstable air
mass along and just ahead of the front, while a region of broad
convergence and lift along the frontal zone combined with the
unstable conditions will support at least scattered showers and
thunderstorms and possibly an organized thunderstorm complex or
two Sunday night, Monday and Monday night.

Present indications are the front will then lift back northward on
Tuesday Night-Wednesday in response to high Plains cyclogenesis
associated with an upper trof ejecting northeastward out of the
southwestern U.S.. A defined cold fropa is not evident within the
7 day forecast period and the current increase in pops late week
reflect the increased presence of a cold front to our west and the
moist and unstable warm sector. Temperatures look seasonably warm
all of next week.

Glass

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1137 PM CDT Fri May 1 2015

Mid and high clouds will continue to overspread the area tonight
with ceilings AOA 8,000 FT. Few sprinkles continue to show up on
radar and in obs, but no visibility restrictions have been
reported, nor are any expected. VFR flight conditions with
ceilings continuing AOA 8,000 FT are expected to prevail on
Saturday with wind turning to the south-southwest during the mid
morning.

Specifics for KSTL:

VFR flight conditions with ceilings AOA 8,000 FT will continue to
prevail through Saturday. Wind will likely veer to nearly a direct
crosswind Saturday morning, but wind speed still looks to be below
10kts. Should see the wind back to the south during the late
morning or early afternoon.

Carney

&&

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

$$

WFO LSX






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