Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 180907
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
407 AM CDT Sat Apr 18 2015

.SHORT TERM:  (Through Late This Afternoon)
Issued at 406 AM CDT Sat Apr 18 2015

The upper level low over CO will move slowly eastward today.  As
southwest flow shortwaves move into our area, along with increasing
upper level divergence ahead of the the upper level low/trough,
scattered showers and storms moving north northeastward through
western MO should eventually translate eastward into the western
portion of our forecast area, west of the Mississippi River this
afternoon.  Followed the convective forecast of the 4 km NCEP WRF
for today which appears to have a pretty good handle on the current
convection.  Above normal temperatures can be expected again today,
slightly cooler across the western portion of the forecast area due
to increased cloud cover along with the potential for at least
scattered showers/storms this afternoon.

GKS

.LONG TERM:  (Saturday through Next Friday)
Issued at 317 PM CDT Fri Apr 17 2015

Models are now a little slower with onset of showers and
thunderstorms on Saturday, with best chances over central MO
Saturday afternoon. Otherwise, will see highs in the low to mid 70s
with coolest temps over central MO due to the cloud cover and
precipitation.

Models persistent in developing a strengthening low along warm front
with it lifting northeastward from the MO bootheel to southern Lake
Michigan by Sunday evening. So now forecast area remains on cool
side of system with severe chances on Sunday afternoon and evening
looking less likely most locations, though far southern portions of
forecast area could still see some severe weather. Showers will be
predominant on Sunday with less instability expected so adjusted
weather grids to just mention showers with a chance of
thunderstorms. Overall could see widespread one inch rainfall
amounts through the weekend.

Precipitation comes to an end by Monday with cooler and drier
weather for the first part of the work week. Then extended models
try to bring in another wet period from Tuesday night through Friday
but confidence is low on timing and placement of precipitation so
kept slight chance/chance pops through this period. Highs will be
60s Monday through Friday with overnight lows in the 40s.

Byrd

&&

.AVIATION:  (For the 06z TAFs through 06z Saturday Night)
Issued at 1148 PM CDT Fri Apr 17 2015

Specifics for KCOU, KUIN: A few showers are possible at KCOU after
12z. MVFR conditions are possible if one of the showers happens to
move directly over KCOU. There is a much greater chance of
SHRA/TSRA after 19/03z at both KCOU and KUIN when a slow-moving
low pressure system approaches the region.

Specifics for KSTL, KSUS, KCPS: VFR conditions are expected for at
least the first 0-6 hours except at KSUS where light fog is
possible towards daybreak given the airport`s proximity to the
river. Elsewhere, increasing cirrus overnight and the lack of a
moisture source adjacent to the airport should limit any fog
formation. SHRA/TSRA chances increase greatly after 19/03z when a
slow-moving low pressure system approaches the region.

Kanofsky

&&

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

$$

WFO LSX






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