DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 101628
SWODY1
SPC AC 101626

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1126 AM CDT THU MAY 10 2012

VALID 101630Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF CNTRL AND SRN
TX...

...SYNOPSIS...

A PROGRESSIVE...SPLIT FLOW PATTERN WILL EXIST ACROSS THE CONUS THIS
PERIOD WITH THE PRIMARY FEATURE OF INTEREST BEING SUBTROPICAL BRANCH
UPPER LOW WHICH WILL TRANSLATE FROM NWRN MEXICO INTO CNTRL TX.
WITHIN THE POLAR BRANCH OF WESTERLIES...A TROUGH WILL AMPLIFY FROM
ERN CANADA THROUGH NEW ENGLAND TO THE MID-ATLANTIC
COAST...DOWNSTREAM FROM A MIGRATORY SHORTWAVE TROUGH MOVING THROUGH
THE CANADIAN PRAIRIE PROVINCES AND NRN PLAINS.

AT THE SURFACE...THE TENDENCY FOR BAROCLINIC ZONE LOCATED ACROSS
PORTIONS OF THE LOWER RIO GRANDE VALLEY AND S-CNTRL TX TO LIFT NWD
AHEAD OF UPPER LOW MAY BE OFFSET BY CONVECTIVE COLD POOL GENERATION
TO THE N...YIELDING LITTLE NET MOVEMENT TO FRONT. THE ERN EXTENSION
OF THIS BOUNDARY OVER THE CNTRL FL PENINSULA WILL...HOWEVER...
CONTINUE SWD THROUGH THE REMAINDER OF THE STATE. ELSEWHERE...A COLD
FRONT ASSOCIATED WITH THE N-CNTRL CONUS SHORTWAVE TROUGH WILL
ADVANCE ACROSS THE NRN PLAINS INTO UPPER MS VALLEY WITH SWRN PORTION
OF BOUNDARY MOVING SWD INTO THE CNTRL HIGH PLAINS.

...EDWARDS PLATEAU/CONCHO VALLEY EWD TO THE UPPER TX COAST AND SWD
INTO DEEP S TX TODAY AND TONIGHT...

12Z CRP/BRO/DRT SOUNDINGS SHOWED THE PRESENCE OF A VERY MOIST
ENVIRONMENT /I.E. PW VALUES OF 1.5-2.0 INCHES/ AND STEEP MIDLEVEL
LAPSE RATES WHICH ARE CONTRIBUTING TO MLCAPE VALUES OF 1500-2500
J/KG AS OF MID MORNING. INCREASED DIABATIC WARMING OF BOUNDARY
LAYER COUPLED WITH COOLING MIDLEVEL TEMPERATURES WILL SUPPORT
FURTHER DESTABILIZATION THROUGH PEAK OF THE DIURNAL HEATING CYCLE
WITH ENVIRONMENT BECOMING STRONGLY UNSTABLE AT LOCATIONS SOUTH OF
THE FRONT.

REGENERATIVE STRONG-SEVERE TSTM DEVELOPMENT IS ANTICIPATED THROUGH
MUCH OF THE D1 PERIOD AS FORCING FOR ASCENT ATTENDANT TO UPPER LOW
EDGES EWD AND INTERACTS WITH THE MOIST...MODERATE-STRONGLY UNSTABLE
ENVIRONMENT. MORE SPECIFICALLY...A NOTABLE INCREASE IN STORM
COVERAGE AND VIGOR IS ANTICIPATED LATER THIS AFTERNOON INTO EVENING
ACROSS PORTIONS OF THE EDWARDS PLATEAU INTO THE HILL COUNTRY IN
ASSOCIATION WITH A STRONG VORTICITY MAXIMUM ROTATING AROUND
PERIPHERY OF UPPER LOW.

THE EWD PROGRESSION OF MID AND HIGH-LEVEL JET STREAKS ACROSS THE
LOWER RIO GRANDE VALLEY WILL RESULT IN PRONOUNCED VERTICAL VEERING
OF WINDS WITH HEIGHT WITH EFFECTIVE BULK SHEAR STEADILY
STRENGTHENING TO 50-60 KT. AS SUCH...THE ENVIRONMENT WILL BECOME
INCREASINGLY SUPPORTIVE OF INTENSE SUPERCELLS CAPABLE OF VERY LARGE
HAIL...TORNADOES...AND DAMAGING WIND GUSTS. UPSCALE GROWTH INTO ONE
OR MORE FORWARD-PROPAGATING MCSS IS POSSIBLE TONIGHT WITH THE
POTENTIAL FOR CORRIDORS OF WIND DAMAGE.

...E-CNTRL/SERN FL PENINSULA THIS AFTERNOON...

LARGE-SCALE FORCING FOR ASCENT WILL REMAIN NEGLIGIBLE ACROSS THE
AREA...BUT THE PRESENCE OF DEEP WLY FLOW SHOULD ENHANCE CONVERGENCE
ALONG THE ERN SEA BREEZE THIS AFTERNOON. WHEN COUPLED WITH SWD
ADVANCEMENT OF COLD FRONT...EXPECT WIDELY SCATTERED-SCATTERED TSTM
DEVELOPMENT THIS AFTERNOON WITHIN A THERMODYNAMIC ENVIRONMENT
FEATURING MLCAPE OF 1000-2000 J/KG. THIS INSTABILITY WILL ALIGN
WITH AN EWD-DEVELOPING SUBTROPICAL UPPER JET STREAK WITH SETUP
SUPPORTIVE OF MULTICELL AND MARGINAL SUPERCELL STRUCTURES CAPABLE OF
LOCALLY DAMAGING WINDS...SOME HAIL...AND PERHAPS A BRIEF TORNADO.

...NRN PLAINS THIS AFTERNOON AND EVENING...

DESPITE THE PRESENCE OF A RELATIVELY DRY AIR MASS /PER 12Z REGIONAL
SOUNDINGS/...MODEL GUIDANCE INDICATE THAT STEEP MIDLEVEL LAPSE RATES
AND STRONG DAYTIME HEATING WILL YIELD A MODERATELY UNSTABLE
ENVIRONMENT BY AFTERNOON WITH MLCAPE APPROACHING 1000 J/KG. A
DEEPENING FRONTAL CIRCULATION WILL COMBINE WITH INCREASING HEIGHT
FALLS/FORCING FOR ASCENT DOWNSTREAM FROM POLAR BRANCH SHORTWAVE
TROUGH TO FOSTER ISOLATED TSTMS BY LATE AFTERNOON OR EARLY EVENING.
VERTICAL SHEAR WILL REMAIN MARGINALLY STRONG FOR STORM
ORGANIZATION/SUSTENANCE...BUT THE PRESENCE OF THE STEEP LAPSE RATES
AND DEEPLY MIXED BOUNDARY LAYER MAY PROMOTE LOCALLY STRONG WIND
GUSTS AND PERHAPS SOME HAIL.

..MEAD/BUNTING/LEITMAN.. 05/10/2012

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