DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 101950
SWODY1
SPC AC 101948

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0248 PM CDT WED OCT 10 2012

VALID 102000Z - 111200Z

...NO SVR TSTM AREAS FORECAST...

SHOWERS AND ISOLATED THUNDERSTORMS HAVE CONGREGATED ALONG A LOW
LEVEL CONFLUENCE ZONE ACROSS THE WRN GULF BASIN THIS AFTERNOON.
OTHER SHOWERS ARE SLOWLY DEEPENING ALONG OUTFLOW/SEA BREEZE SURGE AS
IT SPREADS INLAND ALONG THE MIDDLE TX COAST. GIVEN THE WEAK RIDGING
ALOFT IT APPEARS LOW LEVEL HEATING ALONG THESE BOUNDARIES WILL BE
THE FOCUS FOR DEEP CONVECTION THROUGH THE AFTERNOON.

ELSEWHERE...ISOLATED THUNDERSTORMS WILL CONTINUE TO EVOLVE ACROSS
PARTS OF THE GREAT BASIN WHERE STRONG HEATING/STEEP LAPSE RATES
COINCIDE WITH LEADING EDGE OF FORCING AHEAD OF CA UPPER LOW.

EARLIER THOUGHTS REGARDING CONVECTION ACROSS S FL REMAIN.

..DARROW.. 10/10/2012

.PREV DISCUSSION... /ISSUED 1125 AM CDT WED OCT 10 2012/

...SYNOPSIS...
THE NRN STREAM WILL REMAIN OVER THE NRN PLAINS/GREAT LAKES/NEW
ENGLAND THROUGH TONIGHT...WHILE A SEPARATE CLOSED LOW WILL MOVE
SLOWLY EWD NEAR THE CENTRAL/SRN CA COAST. ONE BAND OF CONVECTION
WITH EMBEDDED THUNDERSTORMS WILL GRADUALLY SPREAD INLAND ACROSS THE
CENTRAL CA COAST WITH THE MIDLEVEL COLD CORE...AND ANOTHER BROKEN
BAND OF CONVECTION IS EXPECTED INVOF THE LOWER CO RIVER VALLEY
WITHIN THE ZONE OF ASCENT DOWNSTREAM FROM THE MIDLEVEL LOW...WHERE A
NARROW CORRIDOR OF LOW-LEVEL MOISTENING IN UNDERWAY.

...E TX THIS AFTERNOON INTO ERN OK/AR OVERNIGHT...
DOWNSTREAM FROM THE CA CLOSED LOW...SHORTWAVE RIDGING IS EXPECTED
OVER THE SRN PLAINS. A TROPICAL BOUNDARY LAYER WITH MID 70S
DEWPOINTS WILL SPREAD INLAND ACROSS TX...TO THE S OF A
QUASI-STATIONARY FRONT ACROSS CENTRAL/NE TX AND NW LA. ISOLATED
THUNDERSTORMS WILL BE POSSIBLE WITHIN THIS MOIST AIR MASS THIS
AFTERNOON ACROSS THE MIDDLE AND UPPER TX COASTS...THOUGH COVERAGE
WILL BE LIMITED IN A WEAKLY FORCED ENVIRONMENT. FARTHER INLAND
ALONG THE FRONT...THE MESOSCALE ENVIRONMENT WILL FEATURE SUFFICIENT
BUOYANCY AND DEEP-LAYER VERTICAL SHEAR FOR ORGANIZED STORMS.
HOWEVER...OTHER THAN WEAK LOW-LEVEL ASCENT ALONG THE BOUNDARY...THE
LARGER-SCALE ENVIRONMENT WILL NOT BE PARTICULARLY FAVORABLE FOR
THUNDERSTORM DEVELOPMENT GIVEN THE RISING HEIGHTS ALOFT AND GRADUAL
EWD EXPANSION OF THE WARM EML ABOVE THE BOUNDARY LAYER.
THUS...DIURNAL THUNDERSTORM DEVELOPMENT IS QUITE UNCERTAIN ALONG THE
BOUNDARY THIS AFTERNOON...AND ELEVATED CONVECTION MAY NOT FORM UNTIL
THE END OF THE PERIOD TO THE N OF THE FRONT IN THE WAA REGIME WITH A
STRENGTHENING SWLY LLJ. GIVEN THESE CONCERNS...WILL OPT TO NOT ADD
ANY HAIL PROBABILITIES IN THIS UPDATE.

...SE FL COAST THIS AFTERNOON...
A WEAK E COAST SEA BREEZE WILL REMAIN NEAR THE COAST THIS AFTERNOON
IN A NLY LOW-LEVEL FLOW REGIME. THE 12Z MFL SOUNDING SHOWED THE
POTENTIAL FOR MLCAPE NEAR 3000 J/KG WITH AFTERNOON TEMPERATURES OF
86-90 F...WITH LITTLE CONVECTIVE INHIBITION. THUNDERSTORM COVERAGE
WILL LIKELY REMAIN RATHER SPARSE IN THE WEAKLY FORCED
ENVIRONMENT...THOUGH AN ISOLATED WET MICROBURST CANNOT BE RULED OUT
GIVEN THE DEGREE OF BUOYANCY AND DRYING IN THE 600-400 MB LAYER OVER
THE PAST 12 HOURS. THE OVERALL RISK APPEARS TOO LOW TO WARRANT THE
INTRODUCTION OF DAMAGING WIND PROBABILITIES.

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