SWODY1
SPC AC 111256
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0756 AM CDT WED APR 11 2012
VALID 111300Z - 121200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
TONIGHT FOR PARTS OF THE SRN/CENTRAL HIGH PLAINS...
...SYNOPSIS...
A SURFACE LOW ACROSS ID/NV THIS MORNING WILL DEVELOP NEWD TO
CENTRAL/NRN MT BY TONIGHT...IN ADVANCE OF A SHORTWAVE TROUGH OVER
SRN CA THAT WILL EJECT NEWD TO MT/WY IN THE SAME TIME FRAME.
DOWNSTREAM...THE RIDGE ALOFT WILL MOVE EWD FROM THE HIGH PLAINS THIS
MORNING TO THE ERN PLAINS BY TONIGHT. A SURFACE COLD FRONT NOW
STRETCHING FROM THE LOWER MS VALLEY TO CENTRAL FL WILL CONTINUE TO
MOVE SWD/SWWD IN THE WAKE OF A MIDLEVEL TROUGH WHICH WILL BEGIN TO
PROGRESS OFF THE ATLANTIC COAST BY TONIGHT. THE NW EXTENT OF THE
FRONT WILL MOVE LITTLE FROM ITS CURRENT POSITION ALONG AN AXIS FROM
SE CO TO SRN OK.
...SRN HIGH PLAINS THIS AFTERNOON INTO EARLY TONIGHT...
BOUNDARY LAYER DEWPOINTS IN THE MID 40S TO LOW 50S ARE PRESENT FROM
THE CO FRONT RANGE SWD TO ERN NM/W TX...WHILE THE SOMEWHAT RICHER
MOISTURE /GREATER MIXING RATIOS/ IS CONFINED TO THE SABINE RIVER
VALLEY AND NW GULF COAST. A BAND OF ELEVATED STORMS IS ONGOING FROM
NRN OK TO CENTRAL AR...THOUGH THIS CONVECTION IS EXPECTED TO WEAKEN
LATER THIS MORNING AS THE WEAK LLJ AND ASSOCIATED WAA DIMINISH.
FARTHER W...OVERNIGHT CONVECTION ACROSS THE TX PANHANDLE HAS
DISSIPATED...AND ANY REMNANT OUTFLOW WILL BECOME QUITE DIFFUSE BY
MIDDAY.
DESPITE SOME MID-HIGH CLOUDS THIS MORNING...SURFACE HEATING SHOULD
BE SUFFICIENT BY AFTERNOON TO WEAKEN CONVECTIVE INHIBITION AND
SUPPORT SCATTERED THUNDERSTORM DEVELOPMENT ALONG A DIFFUSE
DRYLINE/LEE TROUGH NEAR THE ERN NM/TX BORDER. MID-UPPER SWLY FLOW
WILL GRADUALLY INCREASE THIS AFTERNOON THROUGH TONIGHT OVER THE HIGH
PLAINS AS THE MIDLEVEL RIDGE MOVES EWD. THE COMBINATION OF MLCAPE
OF 1000-1500 J/KG...SUPPORTED BY THE 12Z AMA SOUNDING...AND
EFFECTIVE BULK SHEAR RANGING FROM 35-45 KT WILL SUPPORT A RISK OF
HIGH-BASED SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING
WINDS. HIGHER BOUNDARY LAYER RH AND STRENGTHENING LOW-LEVEL SHEAR
THIS EVENING ALONG THE FRONT FROM THE NRN TX PANHANDLE TO EXTREME SE
CO COULD ALSO SUPPORT A COUPLE OF TORNADOES. OTHERWISE...THE
DIURNAL STORMS COULD GROW INTO ONE OR MORE CLUSTERS BY LATE
EVENING/EARLY TONIGHT IN RESPONSE TO OUTFLOW MERGERS AND INCREASING
WAA WITH A 30-40 KT SLY LLJ.
...NRN ROCKIES LATE THIS AFTERNOON/EVENING...
THOUGH MOISTURE WILL BE LIMITED ACROSS THIS AREA...STEEP LAPSE RATES
AND ASCENT IN THE EXIT REGION OF THE MID-UPPER JET COULD SUPPORT A
FEW THUNDERSTORMS LATER THIS AFTERNOON/EVENING. THE MORE PROBABLE
AREA WILL BE THE HIGHER TERRAIN OF WRN MT/NERN ID...WHERE THE STEEP
LAPSE RATES AND DEEP-LAYER SLY SHEAR COULD SUPPORT GUSTY OUTFLOW
WINDS AND SMALL HAIL.
..THOMPSON/ROGERS.. 04/11/2012
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