DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 141605
SWODY1
SPC AC 141602

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1102 AM CDT MON SEP 14 2009

VALID 141630Z - 151200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR A LARGE PART OF UTAH...

...UT...
UPPER TROUGH HAS MOVED INLAND OVER CA THIS AM AND BY 12Z TUE
FORECASTED TO BE A CLOSED LOW CENTRAL UT. MOISTURE HAS SPREAD NEWD
AHEAD OF THE TROUGH THRU THE INTERMOUNTAIN REGION OVERNIGHT. THE
LARGE SCALE ASCENT AND COOL AIR ALOFT/STEEP LAPSE RATES/ WITH
APPROACHING TROUGH HAVE INITIATED THUNDERSTORMS VICINITY UT/NV
BORDER THIS AM. HEATING COMBINED WITH THE AVAILABLE MOISTURE...WILL
LEAD TO AN INCREASE IN INSTABILITY ACROSS MUCH OF UT BY MID
AFTERNOON WITH MLCAPES RANGING UPWARD FROM 500-1000 J/KG. WITH DEEP
LAYER SHEAR TO 30KT...SURFACE BASED STORMS WILL INCREASE DURING THE
AFTERNOON...POSSIBLY DEVELOP CLUSTERS AND SHORT LINES. WITH A
DEEPLY MIXED BOUNDARY LAYER...GUSTY WINDS...BRIEFLY SEVERE WILL
DEVELOP E AND NE ACROSS CENTRAL/UT THIS AFTERNOON. IN ADDITION HAIL
WILL BE LIKELY WITH STRONGEST UPDRAFTS GIVEN THE COOL AIR ALOFT AND
STEEP LAPSE RATES...THEREFORE HAVE INTRODUCED A LOW END SLIGHT RISK
FOR THIS AFTERNOON/EVENING.

...CENTRAL GULF COAST STATES...
A TROPICAL AIR MASS RESIDES ACROSS LOWER MS VALLEY IN ADVANCE OF THE
WEAK SURFACE/UPPER LOW CURRENTLY OVER ERN TX. SVR/TOR POTENTIAL AS
OVER THE WEEKEND WILL BE LIMITED BY THE RELATIVELY WEAKLY SHEARED
ENVIRONMENT. HOWEVER TODAY THERE WILL BE MORE HEATING EWD ACROSS LA
AND SRN MS...LEADING TO THE THREAT FOR DISCRETE STORM DEVELOPMENT
AND POSSIBLY WEAK ROTATION.

HAVE CONTINUED A MARGINAL RISK OF BRIEF TORNADOES AND WET MICRO
BURSTS...BUT WITH THE MARGINAL SHEAR...DO NOT EXPECT STORMS TO BE
ORGANIZED OR OF LONG DURATION.

..HALES/GARNER.. 09/14/2009

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