DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 120450
SWODY1
SPC AC 120448

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1148 PM CDT FRI MAY 11 2012

VALID 121200Z - 131200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
IN THE MID AND UPPER LEVELS...AN INITIALLY CLOSED LOW OVER THE
OZARKS WILL WEAKEN AS IT EVOLVES INTO AN OPEN SHORTWAVE TROUGH
EMBEDDED WITHIN A FETCH OF SWLYS BETWEEN A BROAD AREA OF CYCLONIC
FLOW COVERING THE CNTRL/N-CNTRL STATES AND ROCKIES...AND A RIDGE
MOVING EWD ACROSS THE ERN STATES. THE AXIS OF THE SHORTWAVE TROUGH
WILL EXTEND SWD TO THE GULF COAST WHILE SHIFTING EWD THROUGH THE
PERIOD.

...LOWER MS RIVER VALLEY/CNTRL GULF COAST STATES TODAY INTO
TONIGHT...
AS DCVA IN ASSOCIATION WITH THE AFOREMENTIONED SHORTWAVE TROUGH
INTERACTS WITH A BROAD BAROCLINIC ZONE INVOF THE GULF COAST...A WEAK
SFC LOW IS FORECAST TO BECOME SOMEWHAT BETTER DEFINED OVER THE
SABINE RIVER VALLEY. THE LOW WILL DEVELOP NEWD ACROSS PORTIONS OF LA
AND MS IN RESPONSE TO LEADING WAA...WHICH WILL ALSO SUPPORT MULTIPLE
ROUNDS OF SCATTERED TO NUMEROUS CONVECTION THROUGH THE PERIOD.
MARGINAL INSTABILITY ACROSS THE WARM SECTOR ACCOMPANYING THE SFC LOW
MAY SUPPORT A THREAT FOR STRONG STORMS OWING TO 30-35 KT OF DEEP
SHEAR WITHIN A ZONE OF ENHANCED MID-LEVEL FLOW ATTENDANT TO THE
SHORTWAVE TROUGH. FORECAST SOUNDINGS SUGGEST THAT MODESTLY STRONG
LOW-LEVEL SHEAR...PARTICULARLY INVOF A NNEWD-ADVANCING WARM
FRONT...AMIDST SFC DEWPOINTS IN THE MIDDLE/UPPER 60S...COULD BE
FAVORABLE FOR A FEW ROTATING STORMS CAPABLE OF PRODUCING MARGINALLY
SVR WIND GUSTS AND PERHAPS A TORNADO.

HOWEVER...WIDESPREAD CLOUDS AND PRECIPITATION WILL HAVE THE
POTENTIAL TO SUPPRESS A GREATER INLAND PENETRATION OF RICHER
LOW-LEVEL MOISTURE AND GREATER BUOYANCY THAT WILL CHARACTERIZE THE
MARINE LAYER OVER THE GULF OF MEXICO. THIS WILL ESPECIALLY BE THE
CASE GIVEN THE RELATIVELY WEAK SFC LOW INTENSITY AND WEAKENING
MID/UPPER-LEVEL LOW/TROUGH. FURTHERMORE...MID-LEVEL LAPSE RATES ARE
NOT EXPECTED TO BE STEEP...PARTLY OWING TO PERSISTENT CONVECTIVE
OVERTURNING. IT IS POSSIBLE THAT POCKETS OF INSOLATION/DIABATIC
HEATING MAY EVOLVE THROUGH THE DAY...WHICH COULD YIELD ONE OR MORE
CORRIDORS OF STEEPER LOW-LEVEL LAPSE RATES AND SOMEWHAT HIGHER SVR
POTENTIAL. HOWEVER...CONFIDENCE IN THE DEVELOPMENT/LOCATION OF SUCH
CORRIDORS IS TOO LOW FOR HIGHER SVR PROBABILITIES AT THIS TIME.

...PORTIONS OF SRN CO/CENTRAL NM/PARTS OF THE TRANS-PECOS REGION OF
SWRN TX THIS AFTERNOON AND EVENING...
A SHORTWAVE TROUGH WILL MOVE SSEWD ACROSS THE ROCKIES WITHIN THE
AFOREMENTIONED BROAD AREA OF CYCLONIC FLOW. ASCENT LEADING THE
SHORTWAVE TROUGH COMBINED WITH MOIST/MODEST UPSLOPE FLOW WILL
SUPPORT ISOLATED TO SCATTERED THUNDERSTORMS. ADDITIONALLY...DEEP
SHEAR...ENHANCED BY AN INCREASE IN MID/HIGH-LEVEL FLOW ACCOMPANYING
THE SHORTWAVE TROUGH...MAY BE SUFFICIENT FOR A FEW
SUSTAINED/ORGANIZED/STRONGER TSTMS CAPABLE OF PRODUCING MARGINALLY
SVR HAIL/WIND.

...DEEP SOUTH TX/RIO GRANDE VICINITY THIS AFTERNOON AND TONIGHT...
ASCENT ALONG A DIFFUSE FRONT AND UPSLOPE TRAJECTORIES COULD BE
SUFFICIENT FOR THE DEVELOPMENT OF AN ISOLATED THUNDERSTORM OR TWO.
THE ANTICIPATED WEAK ASCENT YIELDS CONSIDERABLE UNCERTAINTY
REGARDING THE OCCURRENCE OF CONVECTION. FORECAST SOUNDINGS SUGGEST
THAT MODERATE TO PERHAPS STRONG INSTABILITY AND MODEST
MID/HIGH-LEVEL FLOW MAY SUPPORT A CONDITIONAL THREAT FOR ORGANIZED
CONVECTIVE STRUCTURES CAPABLE OF PRODUCING MARGINALLY SVR HAIL/WIND.
HOWEVER...CONFIDENCE IN THE OCCURRENCE OF CONVECTION IS CURRENTLY
TOO LOW FOR ANY SVR PROBABILITIES AT THIS TIME.

..COHEN/DARROW.. 05/12/2012

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