Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 302022
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
322 PM CDT Tue Sep 30 2014

.SHORT TERM:  (Through Late Tonight)
Issued at 300 PM CDT Tue Sep 30 2014

Cu field on vis satellite marking the front quite well and currently
extends from through southwest Iowa to just north of St. Louis
into southern IL. The front may sag a tad south over eastern MO
into IL tonight as the surface winds back to more east-southeasterly,
but the portion of the front in our area is largely expected to
remain unactive. Futher west/northwest however the LLJ shifts
eastward from the Plains overnight and becomes focused in the
vicinity of the front across northwest MO into southwest Iowa
favoring the highest shower/thunderstorm potential. Lows once
again tonight coolest from the eastern Ozarks through southern IL.
May once again see some patchy radiational fog as well.

Glass

.LONG TERM:  (Wednesday through Next Tuesday)
Issued at 300 PM CDT Tue Sep 30 2014

Active weather unfolds Wednesday and especially in the Wednesday
night into Thursday evening time. Multicellular convection is
expected to evolve on Wednesday afternoon across northwest MO and
progress into central and northeast MO during the late afternoon.
High temperatures will remain above average.

Thunderstorms are expected to really get going on Wednesday
night. At least one disturbance in the southwest flow aloft will
traverse northern MO Wednesday night, and this combined with a
veering and strengthening southwesterly LLJ will provide favorable
convergence/lift for convection across northern MO into west
central IL - especially along and north of a Jefferson City to
Litchfield line. Repetitive convection and some locally heavy rain
is certainly within the realm in this region. Thunderstorms remain
likely Thursday and Thursday night with the potential for some
strong-severe storms. This potential will probably be intimately
controlled by mesoscale features. Showers and thunderstorms are
expected to be ongoing Thursday morning across northern MO into
central IL with a convective outflow boundary likely to their
south. This boundary along with a pre-frontal convergence zone
will dictate to some degree the best instability and low-level
shear. Otherwise the advancing cold front and attendant short wave
trof will provide deep large scale ascent, and deep layer shear is
favorable for organized severe during the afternoon and evening
with the orientation suggestive of a linear mode. The vast
majority of showers and thunderstorms should be located well into
Illinois by 06z Friday and east of the CWA by daybreak Friday.

Friday is looking more and more like a typically blustery fall day
with much cooler temperatures and gusty northwest winds. A deep
long wave trof, which has become progressively stronger in the
latest model runs, will dominate the eastern half of the nation
from the weekend into early next week. This will result in below
average temperatures for most of that period.

Glass

&&

.AVIATION:  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1255 PM CDT Tue Sep 30 2014

Clouds are dissipating rapidly over central Illinois and will soon
exit at KUIN. Expect mainly dry and VFR conditions through the TAF
period. Only exception may be at KSUS where river fog may develop
late tonight in close proximity to the terminal.

Specifics for KSTL: Expect dry and VFR conditions the next 30
hours.

Britt

&&

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

$$

WFO LSX





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