DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 151231
SWODY1
SPC AC 151229

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0729 AM CDT TUE MAY 15 2012

VALID 151300Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS UPPER MS VALLEY/GREAT LAKES
REGION...

...THERE IS A SLGT RISK OF SVR TSTMS MUCH OF SC/NC/VA/MD...

...SYNOPSIS...
A STRONG MID-UPPER LEVEL JET WILL ROTATE AROUND A HUDSON BAY
LOW...AMPLIFYING A TROUGH OVER THE GREAT LAKES REGION. AN ATTENDANT
SURFACE COLD FRONT WILL PROGRESS SEWD...INFLUENCING
AFTERNOON/EVENING THUNDERSTORM DEVELOPMENT BEFORE REACHING WRN
NY/PA...THE OH AND MID MS VALLEYS AND CNTRL PLAINS OVERNIGHT.

FARTHER S AND E...A BROAD UPPER TROUGH AND MAINLY DIURNAL SHOWERS
AND THUNDERSTORMS WILL PERSIST FROM THE WRN GULF NWD INTO THE
NORTHEAST...AMIDST MODEST SWLY FLOW.

TO THE WEST...A NRN SIERRAS UPPER LOW WILL MEANDER INTO THE SRN
GREAT BASIN OVERNIGHT...SUPPORTING ISOLATED HIGH-BASED THUNDERSTORMS
ACROSS THE NORTHWEST...GREAT BASIN...AND NRN INTERMOUNTAIN REGION.

...UPPER MS VALLEY/GREAT LAKES REGION...
AMPLE DIURNAL HEATING WILL SLOWLY ERODE CONVECTIVE INHIBITION BY
AFTERNOON...WITH FRONTAL FORCING CONTRIBUTING TO THE DEVELOPMENT OF
A LINE OF STORMS EXTENDING FROM NERN MI SWWD TO SRN IA...GRADUALLY
SAGGING SWD THROUGH THE EVENING. MODEL FORECASTS CONTINUE TO
OVERESTIMATE SURFACE DEW POINT VALUES...AND CONSIDERING THE
ANTECEDENT DRYNESS CONFIRMED BY AREA 12Z SOUNDINGS...FORECAST DEW
POINTS IN THE UPPER 40S TO LOWER 50S SEEM MORE REASONABLE.
REGARDLESS...SBCAPE NEAR 750-1000 J/KG AND MODEST UNIDIRECTIONAL
WLYS MAY BE SUPPORTIVE OF A FEW STRONG TO SEVERE MULTICELLULAR
CLUSTERS CAPABLE OF DMGG WINDS AND HAIL BEFORE NOCTURNAL COOLING
STABILIZES THE BOUNDARY LAYER.

...MUCH OF SC/NC/VA/MD...
12Z VISIBLE IMAGERY SHOWS AREAS OF CLEARING THAT WILL ALLOW FOR
AMPLE SURFACE HEATING AND DESTABILIZATION THROUGH THE AFTERNOON.
SEVERAL AREAS OF CONVECTIVE INITIATION APPEAR POSSIBLE...WITH HI-RES
MODELS SUGGESTING THE PRIMARY INITIATION OCCURRING ALONG THE
APPALACHIANS AS EARLY AS 17Z. ADDITIONAL DEVELOPMENT IS POSSIBLE
ALONG A LEE SURFACE TROUGH AND SEA BREEZE. WV IMAGERY SHOWS AN AREA
OF MOISTENING/IMPLIED ASCENT FROM NRN GA INTO ERN TN/WRN NC AND SC
THAT MAY AID IN EARLIER CONVECTIVE DEVELOPMENT. WITH SEVERAL ROUNDS
OF STRONG TO SEVERE STORMS POSSIBLE...HAVE EXPANDED THE SLIGHT NWD
INTO VA AND MD. SEASONABLY WARM SURFACE TEMPERATURES WILL STEEPEN
LOW LEVEL LAPSE RATES BY AFTERNOON...WITH LOOSELY ORGANIZED CLUSTERS
OF DMGG WINDS AND HAIL OCCURRING AMIDST MODEST DEEP-LAYER SHEAR.
DIURNALLY DRIVEN STORMS WILL WEAKEN SHORTLY AFTER DARK.

...S TX...
LOW LEVEL MOISTURE CONTINUES TO LINGER OVER S TX IN THE WAKE OF
EARLIER CONVECTION. WITH THE MAIN UPPER VORT STILL ACROSS WRN/CNTRL
TX EXPECTED TO ROTATE SEWD...SUFFICIENT DESTABILIZATION MAY BE ABLE
TO OCCUR AHEAD OF THE PRIMARY UPPER FORCING. WEAK LOW-MID LEVEL
LAPSE RATES AND STRENGTHENING DEEP-LAYER WINDS MAY SUPPORT ISOLATED
STRONG TO SEVERE STORMS THIS AFTERNOON AND EVENING.

...CNTRL/NERN FL COASTS...
VERY UNSTABLE AIR MASS AND WEAKLY VEERED LOW LEVEL WINDS MAY BE
SUPPORTIVE OF AN ISOLATED WATERSPOUT THIS MORNING. 12Z VISIBLE
IMAGERY REFLECTS AN AREA OF SURFACE CONVERGENCE N OF MLB THAT MAY BE
A FAVORED AREA FOR DEVELOPMENT. HOWEVER...THE THREAT IS NOT
ANTICIPATED TO EXTEND OVER LAND...SO TORNADO PROBABILITIES HAVE NOT
BEEN INTRODUCED.

..HURLBUT/THOMPSON.. 05/15/2012

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