DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 121730
SWODY2
SPC AC 121728

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT FRI OCT 12 2012

VALID 131200Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS A BROAD PORTION OF THE
CENTRAL U.S....

...SYNOPSIS...
A PROGRESSIVE MID-/UPPER-LEVEL TROUGH IS FORECAST TO SHIFT OUT OF
THE ROCKIES AND INTO THE CENTRAL U.S. THIS PERIOD...WITH
ACCOMPANYING FASTER FLOW FIELD ALSO SPREADING EWD WITH TIME.
MEANWHILE...RIDGING ALOFT IS PROGGED EITHER SIDE OF THE TROUGH --
AFFECTING BOTH THE SWRN AND SERN PORTIONS OF THE U.S. DURING THE
PERIOD.

AT THE SURFACE...A COLD FRONT IS FORECAST TO CROSS THE PLAINS WITH
TIME AS THE UPPER SYSTEM ADVANCES...TRAILING FROM A SOMEWHAT
ILL-DEFINED LOW EXPECTED TO SHIFT EWD ACROSS THE UPPER MIDWEST
REGION THROUGH THE SECOND HALF OF THE PERIOD. THIS LOW/FRONT WILL
BE A FOCUS FOR WIDESPREAD CONVECTION AND ACCOMPANYING SEVERE WEATHER
POTENTIAL.

...THE CENTRAL CONUS...
A COMPLEX SCENARIO CONTINUES TO EVOLVE FOR THE DAY 2 PERIOD...WITH
SOME MODEL DISAGREEMENT ON SYNOPTIC-SCALE SYSTEM PROGRESSION --
PARTICULARLY ACROSS THE CENTRAL AND SRN PLAINS -- COMBINING WITH
QUESTIONS REGARDING BOUNDARY LAYER EVOLUTION TO RESULT IN FAIRLY
SUBSTANTIAL UNCERTAINTY REGARDING BOTH LOCATION AND DEGREE OF SEVERE
POTENTIAL.

CONVECTION WILL LIKELY BE ONGOING FROM PARTS OF W TX NEWD ACROSS THE
CENTRAL PLAINS INTO THE UPPER MIDWEST/UPPER MS VALLEY REGION EARLY.
THIS PRECIPITATION/CLOUD COVER -- PARTICULARLY FROM THE MID MO
VALLEY REGION NEWD -- MAY HINDER APPRECIABLE AIRMASS DESTABILIZATION
THROUGH THE AFTERNOON. THUS -- DESPITE A FAVORABLE KINEMATIC
ENVIRONMENT...DEGREE OF SURFACE-BASED SEVERE RISK REMAINS IN
QUESTION...SUPPORTING A SWWD SHIFT IN SEVERE WEATHER PROBABILITY
THIS FORECAST.

WHILE ONGOING CLOUDS/PRECIPITATION WILL LIKELY AFFECT MORE SRN
PORTIONS OF THE RISK AREA AS WELL...HINTS OF POTENTIAL FOR SOME
DESTABILIZATION BEHIND AN INITIAL BAND OF CONVECTION ARE EVIDENT --
PARTICULARLY GIVEN THE HIGHER THETA-E BOUNDARY LAYER EXPECTED IN
THIS AREA. GIVEN THIS POTENTIAL...AND A BACKGROUND WIND FIELD
SUPPORTIVE OF ORGANIZED/SUPERCELL STORMS...AN AFTERNOON/EVENING
INCREASE IN SEVERE THREAT FROM NWRN MO/ERN KS SWWD INTO WRN N TX
REMAINS POSSIBLE. WHILE DETAILS REGARDING POTENTIAL STORM MODE
ACROSS THIS REGION ARE UNCERTAIN...THREAT FOR HAIL AND DAMAGING
WINDS ALONG WITH ISOLATED TORNADOES EXISTS.

FARTHER NE...LIKELIHOOD FOR A MORE MOIST ADIABATIC LOWER AND MIDDLE
TROPOSPHERE ALONG WITH A MORE VEERED/SWLY BOUNDARY LAYER FLOW FIELD
SUGGESTS THAT DAMAGING WINDS WILL BE THE MAIN SEVERE POTENTIAL IN
THIS REGION.

AS CONVECTION SHIFTS EWD OVERNIGHT AHEAD OF THE PROGRESSING
SYNOPTIC-SCALE SYSTEM...EXPECT A GRADUAL DECREASE IN SEVERE THREAT
CORRESPONDING TO THE DIURNALLY STABILIZING AIRMASS -- PARTICULARLY
ACROSS NRN PORTIONS OF THE RISK AREA.

..GOSS.. 10/12/2012

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