Monday, May 5, 2008

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 051243
SWODY1
SPC AC 051240

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0740 AM CDT MON MAY 05 2008

VALID 051300Z - 061200Z

...THERE IS A SLGT RISK OF SVR TSTMS MAINLY THIS AFTERNOON INTO
EARLY TONIGHT FOR W TX/ERN NM TO WRN KS...

...CENTRAL PLAINS TO SRN HIGH PLAINS THROUGH TONIGHT...
A CLOSED MID LEVEL LOW JUST OFF THE SRN CA COAST WILL BEGIN TO MOVE
EWD TOWARD NRN BAJA AND SW AZ BY TONIGHT. PRESSURE FALLS DOWNSTREAM
FROM THIS LOW WILL MAINTAIN SLY LOW-LEVEL FLOW ACROSS THE
SRN/CENTRAL PLAINS AND RESULT IN MOISTURE TRANSPORT NWD FROM TX.
THE RICHER MOISTURE WILL RESIDE ACROSS CENTRAL/S TX...THOUGH
BOUNDARY LAYER DEWPOINTS IN THE 50S WILL SPREAD NWWD ACROSS W
TX...WITH GENERALLY MID-UPPER 40S FARTHER N INTO KS.

THE INITIAL WAA REGIME AND MOISTENING ABOVE THE SURFACE IS
SUPPORTING A SMALL BAND OF ELEVATED THUNDERSTORMS /WITH SOME HAIL/
OVER WRN KS THIS MORNING. THIS CONVECTION MAY PERSIST INTO MID
MORNING BEFORE WEAKENING. THEREAFTER...DAYTIME HEATING WILL RESULT
IN DEEP MIXING AND WEAKENING OF THE CAP FROM BELOW...AS WELL AS
SUFFICIENT INSTABILITY /MLCAPE VALUES NEAR 1000 J/KG/ FOR SEVERE
STORMS. WIDELY SCATTERED THUNDERSTORMS SHOULD DEVELOP BY LATE
AFTERNOON ALONG THE W EDGE OF THE LOW-LEVEL MOISTURE FROM ERN NM
INTO WRN KS...AND THE CONVECTION WILL SPREAD EWD DURING THE
EVENING/EARLY OVERNIGHT HOURS. VERTICAL SHEAR WILL BECOME AT LEAST
MARGINALLY FAVORABLE FOR HIGH-BASED SUPERCELLS CAPABLE OF PRODUCING
LARGE HAIL INITIALLY...AND DAMAGING GUSTS AS CELL MERGERS AND SOME
UPSCALE GROWTH INTO SMALL CLUSTERS OCCURS BY LATE EVENING.

...S AND SE TX TODAY...
A SLUG OF LOW-MID LEVEL MOISTURE /PW VALUES OF 1.75-1.9 INCHES AND
BOUNDARY LAYER DEWPOINTS IN THE LOW 70S/ HAS SPREAD NWWD INTO S TX.
WEAK SPEED MAXIMA WITHIN THE SUBTROPICAL JET /FROM NRN MEXICO INTO
TX/ HAVE BEEN INTERACTING WITH THE MOISTURE PLUME AND A LOW-LEVEL
WAA REGIME TO SUPPORT DEVELOPMENT OF THUNDERSTORM CLUSTERS OVER THE
RIO GRANDE VALLEY AND SE TX. THE CONVECTION IS EXPECTED TO INCREASE
IN COVERAGE AND PERSIST THROUGH THE DAY...RESULTING IN RELATIVELY
WIDESPREAD CONVECTIVE OVERTURNING OF WITHIN THE MOISTURE PLUME.
WITHIN THE MOIST ENVIRONMENT...LOW-MID LEVEL VERTICAL SHEAR MAY BE
SUFFICIENT FOR A FEW ROTATING STORMS EMBEDDED IN THE LARGER CLUSTERS
FROM LRD TO S OF CRP...AND NEAR HOU. A BRIEF/WEAK TORNADO OR
ISOLATED DAMAGING GUSTS MAY OCCUR WITH THIS ACTIVITY TODAY...AS WELL
AS ISOLATED LARGE HAIL OVER S TX WHERE INSTABILITY IS STRONGER.

...ERN CAROLINAS TODAY...
A RESIDUAL WEAK BAROCLINIC ZONE AND BOUNDARY LAYER DEWPOINTS IN THE
60S WILL PROVIDE A FOCUS FOR THUNDERSTORM DEVELOPMENT TODAY INTO
EARLY TONIGHT ACROSS ERN SC/NC. THE FORMATION OF STORM CLUSTERS
WILL BE AIDED BY THE INTERACTION OF THE WEAK SURFACE FRONT/SEA
BREEZE WITH SEVERAL LOW AMPLITUDE SHORTWAVE TROUGHS MOVING FROM THE
LOWER OH VALLEY TO THE CAROLINAS IN A WNW-ESE FLOW REGIME. MODERATE
INSTABILITY AND 0-6 KM BULK SHEAR AROUND 30-35 KT COULD SUPPORT A
FEW ORGANIZED MULTICELL CLUSTERS OR MARGINAL SUPERCELL STORMS
CAPABLE OF PRODUCING ISOLATED LARGE HAIL AND DOWNBURSTS.

..THOMPSON/SMITH.. 05/05/2008

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