DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 081249
SWODY1
SPC AC 081247

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0647 AM CST FRI MAR 08 2013

VALID 081300Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS FOR PORTIONS OF THE TX
PANHANDLE...TX SOUTH PLAINS...PERMIAN BASIN OF TX...AND FAR WRN
OK...

...PORTIONS OF THE TX PANHANDLE...TX SOUTH PLAINS...PERMIAN BASIN OF
TX...AND FAR WRN OK...
A CLOSED MID/UPPER-LEVEL LOW CENTERED NEAR THE CHANNEL ISLANDS OFF
THE SRN CA COAST PER WATER VAPOR IMAGERY WILL MOVE ASHORE THIS
MORNING AND THEN TRACK EWD/ENEWD OVER THE SWRN STATES THROUGH
TONIGHT. ACCOMPANYING THIS FEATURE...THE LEADING EDGE OF A 500-MB
JET MAX CONTAINING CORE SPEEDS OF 60-90 KT WILL EXTEND OVER THE
SRN/CNTRL HIGH PLAINS THIS EVENING INTO TONIGHT. WHILE MODEST
MID-LEVEL HEIGHT FALLS WILL PRECEDE THE LOW OVER THE CNTRL/SRN HIGH
PLAINS THROUGH THE DAY...STRONGER HEIGHT FALLS -- IN EXCESS OF 90
METERS PER 12 HOURS -- AND STRONGER DCVA WILL NOT EMERGE OVER THE
AREA UNTIL LATE TONIGHT.

IN THE LOW LEVELS...PARTIALLY MODIFIED GULF MOISTURE WILL CONTINUE
TO BE ADVECTED NWD/NNWWD TO THE E OF A SHARPENING DRYLINE THAT IS
FORECAST TO EXTEND FROM SW KS INTO THE TX PANHANDLE AND FARTHER S
INTO SW TX LATE THIS AFTERNOON. MID/HIGH-LEVEL CLOUD COVERAGE
ACCOMPANYING A SUBTROPICAL MOISTURE PLUME EXTENDING INTO THE
AREA...WELL IN ADVANCE OF THE LOW...WILL LIKELY LIMIT THE DEGREE OF
INSOLATION. AND...WITH THE LAGGING DCVA/FORCING FOR
ASCENT...CONVECTION ALONG/E OF THE DRYLINE MAY BE DELAYED UNTIL AS
LATE AS 23Z-03Z. BY THAT TIME...SFC DEWPOINTS WILL LIKELY HAVE ONLY
REACHED INTO THE MIDDLE AND UPPER 50S TO THE E OF THE
DRYLINE...SUPPORTING 300-600 J/KG OF MLCAPE. HOWEVER...THE DRYLINE
CIRCULATION SHOULD BECOME SUFFICIENTLY STRONG/DEEP...AS SFC
CYCLOGENESIS CONTINUES THROUGH THE DAY OVER SERN CO...AND THE CAP
SHOULD BECOME SUFFICIENTLY WEAK FOR ISOLATED TO WIDELY SCATTERED
THUNDERSTORM DEVELOPMENT/INTENSIFICATION OVER THE PERMIAN BASIN AND
TX SOUTH PLAINS EARLY THIS EVENING.

STORMS WILL LIKELY DEVELOP NEWD/ENEWD ACROSS THE TX S PLAINS AND
PANHANDLE BEFORE REACHING FAR WRN OK THROUGH THE EVENING. WHILE DEEP
SHEAR OF 40-60 KT WILL BE SUFFICIENTLY STRONG FOR ORGANIZED STORM
STRUCTURES INCLUDING SUPERCELLS...FORECAST HODOGRAPHS DEPICT A
WEAKNESS IN THE FLOW AROUND 700 MB DEVELOPING THROUGH THE
EVENING...WITH OCCASIONAL VEER-BACK-VEER VERTICAL WIND PROFILES.
AND...WITH THE MARGINAL DEGREE OF INSTABILITY...THE POTENTIAL FOR A
PERSISTENT SUPERCELL CONVECTIVE MODE IS LOW. STORMS MAY BRIEFLY
ACQUIRE CIRCULATIONS BEFORE EVOLVING INTO SMALLER-SCALE
CLUSTERS/QUASI-LINEAR SEGMENTS. SVR HAIL WILL BE THE MAIN CONCERN
WITH THIS ACTIVITY...AND SVR WIND GUSTS WILL ALSO BE POSSIBLE WITH
ANY SFC-BASED CONVECTION. THE GREATEST POTENTIAL FOR SVR STORMS WILL
EXIST PRIOR TO 04Z-05Z. A BRIEF TORNADO CANNOT BE COMPLETELY RULED
OUT WITH ANY SUPERCELL STRUCTURES...MAINLY ACROSS THE CNTRL/ERN TX
PANHANDLE THIS EVENING...OWING TO 250-350 M2/S2 OF EFFECTIVE SRH.
HOWEVER...THE ONSET OF NOCTURNAL STABILIZATION/STRENGTHENING CINH
AND A MIXED CONVECTIVE MODE SHOULD LARGELY LIMIT THE TORNADO THREAT.

CONVECTION WILL SPREAD NEWD ACROSS NWRN OK AND INTO SRN KS THROUGH
THE NIGHT AS A LOW-LEVEL JET STREAM STRENGTHENS ATOP THE STABILIZING
BOUNDARY LAYER. THE SVR THREAT WILL LIKELY DIMINISH AS THIS ACTIVITY
BECOMES REMOVED FROM ANY SFC-BASED BUOYANCY. ADDITIONAL STORMS MAY
DEVELOP OVER THE TX PANHANDLE AND TX SOUTH PLAINS LATE IN THE NIGHT
AS A PACIFIC FRONT ACCOMPANYING THE MID-LEVEL LOW OVERTAKES THE
DRYLINE...WITH THIS ACTIVITY SHIFTING ENEWD/NEWD INTO WRN OK AND SRN
KS THROUGH EARLY SAT. SFC-BASED CINH WILL LIKELY BE TOO SUBSTANTIAL
FOR ANY MORE THAN AN ISOLATED THREAT FOR SVR HAIL AND GUSTY WINDS
WITH THIS ACTIVITY.

...COASTAL AREAS OF SRN CA AND PORTIONS OF SRN AZ...
COLD MID-LEVEL TEMPERATURES AND AMBIENT VERTICAL VORTICITY
ACCOMPANYING A CLOSED LOW TRACKING ACROSS THE REGION WILL SUPPORT
THUNDERSTORMS THAT COULD BRIEFLY ACQUIRE ROTATION. SMALL
HAIL...GUSTY WINDS...AND A MARINE WATERSPOUT OVER THE SRN CA COASTAL
WATERS...WILL BE THE MAIN CONCERNS WITH THIS ACTIVITY.
HOWEVER...LIMITED BUOYANCY WILL LIMIT THE SVR THREAT SUCH THAT SVR
PROBABILITIES ARE NOT WARRANTED AT THIS TIME.

..COHEN/HART.. 03/08/2013

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