SPC AC 070546
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT MON APR 07 2008
VALID 071200Z - 081200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS OK...PARTS OF FAR N TX
AND THE ERN TX PANHANDLE...SRN KS...SWRN MO...AND NWRN AR...
...SYNOPSIS...
LARGE UPPER TROUGH ACROSS THE WRN 2/3 OF THE CONUS IS FORECAST TO
EXPAND SLIGHTLY BUT MAKE LITTLE EWD PROGRESS. WITHIN THE
LARGER-SCALE TROUGH...A SMALL CLOSED LOW -- AND AN ASSOCIATED
SURFACE LOW -- WILL MOVE NEWD ACROSS THE UPPER GREAT LAKES INTO
ONTARIO.
TRAILING END OF THE COLD FRONT ASSOCIATED WITH THE GREAT LAKES LOW
SHOULD BEGIN LIFTING BACK NWD ACROSS THE RED RIVER INTO OK...AS LEE
CYCLOGENESIS OCCURS OVER THE SRN HIGH PLAINS. THIS LOW SHOULD MOVE
EWD ALONG THE BAROCLINIC ZONE INTO OK BY THE END OF THE PERIOD.
...SRN KS/OK AND VICINITY...
WARM FRONT IS FORECAST TO MOVE SLOWLY NWD ACROSS THE RED RIVER INTO
OK DURING THE FIRST HALF OF THE PERIOD...AS LEE LOW DEVELOPS OVER
THE SRN HIGH PLAINS. BY AFTERNOON...THE FRONT SHOULD LIE W-E ACROSS
OK...WITH A DRYLINE EXTENDING SWD FROM SWRN OK ACROSS CENTRAL TX
TOWARD DEL RIO.
S OF THE FRONT/E OF THE DRYLINE...SLOW MOISTENING OF THE BOUNDARY
LAYER IS FORECAST...AS SELY FLOW ADVECTS GULF MOISTURE NWD. BY LATE
AFTERNOON...DEWPOINTS NEAR 60 COMBINED WITH BOUNDARY-LAYER HEATING
BENEATH STEEP LAPSE RATES ALOFT ADVECTING EWD ACROSS THE REGION WILL
RESULT IN MODERATE INSTABILITY /1000 TO 1500 J/KG MIXED-LAYER CAPE/.
AS A WEAK SHORT-WAVE TROUGH EMERGES INTO KS/OK WITHIN LARGER-SCALE
CYCLONIC FLOW ALOFT...FOCUSED UVV INVOF BOTH THE FRONT AND THE
DRYLINE SHOULD RESULT IN ISOLATED TO SCATTERED STORM DEVELOPMENT
OVER WRN OK.
DEEP-LAYER WIND FIELD WILL BE FAVORABLE FOR SUPERCELLS...WITH SELY
LOW-LEVEL FLOW VEERING AND INCREASING WITH HEIGHT TO WLY AT 40 TO 50
KT AT MID LEVELS. THUS -- DEVELOPING UPDRAFTS SHOULD RAPIDLY
ACQUIRE ROTATION AND SPREAD EWD TOWARD CENTRAL OK WITH TIME. THOUGH
LACK OF RICHER BOUNDARY-LAYER MOISTURE SHOULD LIMIT THE OVERALL
TORNADO POTENTIAL SOMEWHAT...ISOLATED TORNADOES ARE EXPECTED --
PARTICULARLY WITH ANY STORM MOVING EWD ALONG W-E SURFACE FRONT.
MORE SIGNIFICANT THREAT WILL BE LARGE HAIL WITH PERSISTENT SUPERCELL
STORMS.
OVERNIGHT...WARM ADVECTION ASSOCIATED WITH LOW-LEVEL JET INCREASING
TO 50-PLUS KT WILL ALLOW ONGOING STORMS TO CONTINUE MOVING EWD
ACROSS OK...WITH AN EXPANSION IN STORM COVERAGE NEAR AND N OF THE
SURFACE BOUNDARY INTO ERN KS/WRN MO. POTENTIAL FOR ISOLATED
TORNADOES SHOULD PERSIST THROUGH THE EVENING NEAR AND S OF THE FRONT
ACROSS OK...WHILE A MORE EXPANSIVE HAIL THREAT IS EXPECTED THROUGH
THE END OF THE PERIOD.
...SRN FL...
SOME DESTABILIZATION IS FORECAST ACROSS S FL...AS SURFACE BOUNDARY
LINGERS ACROSS CENTRAL PORTIONS OF THE PENINSULA. WHILE DEEP-LAYER
WIND FIELD IS FORECAST TO BE FAIRLY WEAK...INSTABILITY MAY BE
SUFFICIENT TO SUPPORT A FEW STRONGER STORMS -- AND THUS WILL
MAINTAIN LOW PROBABILITY HAIL/WIND THREAT ACROSS THIS AREA.
..GOSS.. 04/07/2008
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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