Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 080854
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
354 AM CDT Tue Jul 8 2014

.SHORT TERM:  (Through Late This Afternoon)
Issued at 353 AM CDT Tue Jul 8 2014

The weakening MCS moving southeastward through east central and
southeast MO as well as southwest IL should shift southeast of our
forecast area later this morning.  The cold front now across
northwest MO will move southeastward through the forecast area
today.  Although we could not rule out redevelopment of convection
this afternoon along and just ahead of this cold front, it appears
that the effective low level boundary will be the outflow from this
mornings MCS which will be southeast of our forecast area this
afternoon.  The latest HRRR develops convection late this afternoon
south and southeast of the forecast area.  Even the operational
models afternoon qpf is confined to the extreme southern or
southeastern portion of our forecast area.  For now will include
chance pops across southeast MO and southwest IL, south and east of
STL for this afternoon.  High temperatures today will be slightly
cooler than yesterday due to at least weak cold air advection behind
the cold front and gradually lowering 850 mb temperatures.

GKS

.LONG TERM:  (Tuesday through Next Monday)
Issued at 341 PM CDT Mon Jul 7 2014

(Tuesday through Thursday)

On Tuesday, the front will be moving south and out of the CWA about
the time that thunderstorms will be initiating during the early-mid
afternoon hours.  There is still some potential that one or two of
these storms could become severe before they move out of the CWA
during the late afternoon hours.

The front will then move well south of the area Wednesday into
Thursday as the flow becomes northwesterly aloft.  The area will lie
under mainly subsidence during this period, so have kept these two
days dry.  850 mb temperatures will be between 12-18C promising
below normal temperatures.

(Friday through next Monday)

Warm front is still on track to move through the area on Friday and
Saturday causing temperatures to climb back closer to normal.  The
front will keep scattered thunderstorms in the forecast.  850 mb
temperatures of 18-20C call for temperatures at or just above
normal.  ECMWF sets up northwesterly flow over the area quicker than
the GFS on Saturday and Sunday, so consequently it is trying to
bring a cold front through the CWA faster. This solution is faster
than in previous runs, so went with the slower idea with a cold
front entering the northern part of the CWA on Sunday morning and
move it south across the area through Monday.  Will continue the
chance of thunderstorms into early next week.

Britt

&&

.AVIATION:  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1241 AM CDT Tue Jul 8 2014

Squall line is marching east-southeast through the area with a
large area of stratoform rain behind it. Primary concern will be
wind gusts in excess of 50kts as the line moves through, and
second brief IFR flight conditions in heavy rain. CIGs/VSBYs
improve pretty rapidly to high end MVFR and VFR behind the line
in the lighter rain. Expect this light rain and thunder to
continue for several hours behind the line. Flight conditions may
briefly dip into MVFR in this area, but believe VFR flight
conditions will prevail. Expect rain to end from northwest to
southeast across the area through 12Z Tuesday morning.

Specifics for KSTL:

Squall line is marching east-southeast through the area with a
large area of stratoform rain behind it. Primary concern will be
wind gusts in excess of 50kts as the line moves through, and
second brief IFR flight conditions in heavy rain. CIGs/VSBYs
improve pretty rapidly to high end MVFR and VFR behind the line
in the lighter rain. Expect this light rain and thunder to
continue for several hours behind the line. Flight conditions may
briefly dip into MVFR in this area, but believe VFR flight
conditions will prevail. Expect rain to end from northwest to
southeast...probably ending between 10-12Z at Lambert.

Carney

&&

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

$$

WFO LSX






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