SWODY2
SPC AC 130600
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT MON SEP 13 2010
VALID 141200Z - 151200Z
...THERE IS A SLGT RISK OF SVR TSTMS NORTH-CENTRAL HIGH PLAINS...
...SYNOPSIS...
MODERATELY STRONG/NEARLY ZONAL WESTERLIES WILL REMAIN PREVALENT OVER
THE NORTHERN HALF OF THE CONUS ON TUESDAY IN THE WAKE OF A
DIGGING/AMPLIFYING UPPER TROUGH OVER THE LOWER GREAT LAKES/NORTHEAST
STATES. IN ASSOCIATION WITH THE AFOREMENTIONED UPPER TROUGH...A
SURFACE COLD FRONT WILL CONTINUE A STEADY EAST-SOUTHEASTWARD
PROGRESSION ACROSS NEW ENGLAND/MID ATLANTIC STATES AND SOUTHERN
APPALACHIANS VICINITY. THE WESTERN PORTION OF THE FRONT WILL MOVE
LITTLE AS IT EXTENDS NORTHWESTWARD ACROSS THE LOWER MO
VALLEY/CENTRAL PLAINS...AND INTO THE NORTHERN HIGH PLAINS.
...CENTRAL/NORTHERN PLAINS TO LOWER MO VALLEY/SOUTHERN PLAINS...
AS LOW AMPLITUDE WESTERLIES PERSIST OVER MUCH OF THE
CONUS...MULTIPLE SHORTWAVE TROUGHS ARE FORECAST TO SPREAD EASTWARD
OVER THE GREAT BASIN/INTERMOUNTAIN WEST AND ROCKIES TUESDAY/TUESDAY
NIGHT. INITIALLY...TSTMS ARE EXPECTED ACROSS THE LOWER/MIDDLE MO
VALLEY VICINITY TUESDAY MORNING. THIS WILL BE LARGELY ATTRIBUTABLE
TO A WARM ADVECTION/ISENTROPIC LIFT REGIME TO THE NORTH OF A ROUGHLY
WNW-ESE ORIENTED SURFACE FRONT. SOME OF THESE STORMS COULD YET
PRODUCE SEVERE HAIL INTO TUESDAY...BUT A WEAKENING LOW LEVEL JET
WOULD IMPLY ONLY A LIMITED SEVERE THREAT AT BEST AS STORMS CONTINUE
TO SPREAD EAST-SOUTHEASTWARD THROUGH THE DAY. FARTHER SOUTH...OTHER
TSTM DEVELOPMENT IS POSSIBLE INTO PORTIONS OF THE SOUTHERN PLAINS
AMIDST A MOIST/INSTABILITY AXIS. WHILE EXPECTED TO BE
MARGINAL/ISOLATED...SOME SEVERE THREAT /MAINLY DAMAGING WINDS/ WILL
BE POSSIBLE DURING THE DAY ON TUESDAY ACROSS PORTIONS OF KS/OK.
OTHERWISE...WEST/NORTHWEST OF THESE EARLY DAY SHOWERS/TSTMS...IT
APPEARS AS IF MUCH OF THE NEAR-SURFACE FRONTAL ZONE AND ASSOCIATED
MOIST/INSTABILITY AXIS MAY REMAIN CAPPED FOR MUCH OF THE DAY ACROSS
THE CENTRAL PLAINS. WHILE CINH WILL BE RELATIVELY WEAK...A RESIDUAL
WARM LAYER ALOFT /OWING TO SHORTWAVE RIDGING/ AND MODEST MASS
CONVERGENCE SHOULD CURB THE LIKELIHOOD AND/OR THE EXTENT OF DEEP
CONVECTIVE DEVELOPMENT THROUGH PEAK HEATING...AS MASS FIELDS
OTHERWISE BEGIN TO RESPOND TO UPSTREAM HEIGHT FALLS AS ONE OR MORE
OF THE AFOREMENTIONED PERTURBATIONS ALOFT APPROACH THE HIGH PLAINS.
AS SUCH...THE PROSPECTS FOR APPRECIABLE VIGOROUS TSTM DEVELOPMENT
/AND TIMING THEREOF/ ARE QUESTIONABLE ACROSS NEB/NORTHERN KS IN
SPITE OF AN OTHERWISE FAVORABLE KINEMATIC/THERMODYNAMIC ENVIRONMENT
IN VICINITY OF THE SURFACE FRONTAL ZONE.
THUS...CURRENT THINKING IS THAT THE MOST LIKELY SCENARIO WILL BE FOR
STRONG/SEVERE TSTMS TO DEVELOP ACROSS THE NORTH-CENTRAL HIGH PLAINS
LATE TUESDAY AFTERNOON/EVENING...AS HEIGHTS BEGIN TO RELAX WITH
SOMEWHAT RICHER MOISTURE OTHERWISE RETREATING WESTWARD DURING THE
DAY. TSTMS SHOULD INCREASE IN EARNEST AFTER DARK ACROSS THE
NORTH-CENTRAL PLAINS ALONG/NORTH OF THE SURFACE FRONTAL ZONE...AS
ELEVATED MOISTURE TRANSPORT INCREASES/HEIGHTS CONTINUE TO FALL AHEAD
OF A SOMEWHAT MORE SUBSTANTIAL SHORTWAVE TROUGH CROSSING THE CENTRAL
ROCKIES.
..GUYER.. 09/13/2010
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