Area Forecast Discussion
Issued by NWS St. Louis, MO

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319
FXUS63 KLSX 020552
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1152 PM CST MON FEB 1 2016

.SHORT TERM: (Through Tuesday Night)
Issued at 333 PM CST Mon Feb 1 2016


No major changes to forecast wrt large storm system which impact the
region tonight through Tuesday night. Timing of system looks
slightly delayed compared to yesterday w/ the track of the sfc low
still through NW MO late Tuesday afternoon.

For tonight...increasing low-level warm/moist advection in
conjunction with strengthening UL support as wave moves ENE should
help increase rain chances from west to east late tonight. PoPs have
been trimmed a bit due to slower nature of storm. Added back in a
slight chance of thunder for 0900 to 1200 UTC as NAM model has
several hundred J/kg of MUCAPE.

Round of showers/thunderstorms still looks like a good bet across
much of the CWA during the day on Tuesday. Warm front will surge
northward on Tuesday morning and attempt to destabilize the
atmosphere for sfc-based convective development for the afternoon
hours. Still looks like far eastern portions of the CWA will have
the best chance at strong/severe thunderstorms as this area will
likely have sufficient time to destabilize. Damaging winds still
appear to be the primary threat...though NAM soundings do show a bit
more instability aloft within the hail growth zone. In
addition...strength of low-level shear and helicity as well as low
LCL values could pose an isolated tornadic risk but better chances
of all types of severe activity look to be southeast of the forecast
area.

Strong wind gusts...either via mechanical mixing or through
precipitation loading/downdrafts also remain a concern.
However...still some disagreement on strength of low-level wind
fields between models as well as how deep mixing will be behind
the round of showers/storms for the late afternoon hours.


Gosselin

.LONG TERM: (Wednesday through Next Monday)
Issued at 333 PM CST Mon Feb 1 2016


Cooler/more seasonable air still in the offing beginning on
Wednesday. Expect a cloudy day without much variation in temperature
due to the cloud cover and CAA. Also cannot rule out some flurries
or light snow particularly for portions of northeastern Missouri and
west-central Illinois.

The remainder of the extended looks a little warmer than yesterday
as the mean longwave trough is expected to be a bit further east
than previously forecast. That in turn should yield temperatures
near to slightly above normal through Monday along with mostly dry
weather.

The next chance of precipitation now is expected on Monday with the
passage of an arctic cold front. Much colder weather certainly
appears possible behind this front taking a peek ahead into the
middle of next week.


Gosselin

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1139 PM CST Mon Feb 1 2016

Not many changes from the prev TAFs again. Updated timing to
account for latest trends and guidance. TSRA will move into the
COU region around sunrise and move ewd impacting STL/SUS/CPS
during the late morning into early afternoon hours. Have only
added VCTS to UIN as coverage that far north is more uncertain.
Still expect cigs to improve quickly after precip ends with dry
slot moving into the region. Expect clouds to move back into
terminals, but beyond the current TAF period.


&&

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

$$

WFO LSX



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