Saturday, September 11, 2010

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 110645
SWODY3
SPC AC 110643

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0143 AM CDT SAT SEP 11 2010

VALID 131200Z - 141200Z

...SYNOPSIS...
RELATIVELY LOW-AMPLITUDE MID-LEVEL FLOW FIELD WILL PERSIST ACROSS
MOST OF THE U.S. THIS PERIOD...AS A TROUGH AXIS PERSISTS OFF THE W
COAST...RIDGING REMAINS ACROSS THE CENTRAL U.S./ROCKIES...AND A
SECOND TROUGH SHIFTS SLOWLY ACROSS ERN NOAM. WHILE A RELATIVELY
WEAK SURFACE PATTERN WILL PERSIST ACROSS MOST OF THE U.S. BENEATH
THE AFOREMENTIONED MID-LEVEL REGIME...A W-E BAROCLINIC ZONE ACROSS
THE CENTRAL PLAINS SHOULD FOCUS AFTERNOON/EVENING CONVECTION ACROSS
THIS REGION.

...CENTRAL PLAINS...
SLY LOW-LEVEL FLOW IS FORECAST TO STRENGTHEN A BIT ACROSS THE
CENTRAL PLAINS DAY 3 AS THE LEE TROUGHING/LOW PRESSURE INCREASES.
WITH RESULTING NWD RETURN OF BOUNDARY LAYER MOISTURE...AFTERNOON
HEATING SHOULD RESULT IN THE DEVELOPMENT OF 500 TO 1500 J/KG
MIXED-LAYER CAPE ACROSS THIS REGION. THIS DESTABILIZATION COMBINED
WITH THE PRESENCE OF A WEAK W-E BAROCLINIC ZONE FORECAST TO RESIDE
ACROSS THE KS/NEB VICINITY SUGGESTS THAT SCATTERED AFTERNOON
THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE...AND MAY EXPAND NWD
OVERNIGHT AS AN INCREASING HIGH PLAINS LOW-LEVEL JET SUPPORTS
ELEVATED CONVECTION.

WHILE MODERATE WLY/NWLY FLOW ALOFT WILL EXIST ATOP LOW-LEVEL SLYS --
RESULTING IN AMPLE SHEAR FOR ORGANIZED/ROTATING STORMS...OVERALL
CONVECTIVE COVERAGE AND INTENSITY SHOULD BE LIMITED BY THE PRESENCE
OF LARGE-SCALE RIDGING/SUBSIDENCE ALOFT. THEREFORE...WILL ONLY
INTRODUCE LOW /5%/ SEVERE PROBABILITY ATTM -- THOUGH AN UPGRADE TO
SLIGHT RISK MAY BE POSSIBLE LATER WHEN THE ZONE OF MOST FAVORABLE
POTENTIAL CAN BE MORE ACCURATELY ASCERTAINED.

..GOSS.. 09/11/2010

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