DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 150556
SWODY1
SPC AC 150553

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT WED MAY 15 2013

VALID 151200Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF WCNTRL TX...

...SRN PLAINS...
AN UPPER-LEVEL LOW IS FORECAST TO DEVELOP THIS AFTERNOON ACROSS OK
WITH AN UPPER-LEVEL TROUGH EXTENDING SWD ACROSS WCNTRL TX. AT THE
SFC...A LOW WILL DEEPEN ACROSS WEST TX AS LOW-LEVEL CONVERGENCE
INCREASES ALONG A DRYLINE EXTENDING SWD FROM NEAR CHILDRESS TO
AROUND SAN ANGELO. MODEL FORECASTS SUGGEST SCATTERED THUNDERSTORMS
WILL INITIATE TO THE EAST OF THE DRYLINE THIS AFTERNOON BUT DIFFER
ON THE NORTH TO SOUTH EXTENT OF STORM DEVELOPMENT. THE NAM SOLUTION
IS FURTHER SOUTH MOVING A CLUSTER OF STORMS ESEWD ACROSS THE TX HILL
COUNTRY WHILE THE GFS FOCUSES CONVECTIVE DEVELOPMENT NEAR THE RED
RIVER. IT APPEAR REASONABLE THAT A CLUSTER OF STORMS COULD ORGANIZE
AND PERSIST INTO THE EVENING BUT THE EXACT SCENARIO REMAINS
UNCERTAIN.

FORECAST SOUNDINGS TO THE EAST OF THE DRYLINE LATE THIS AFTERNOON
SHOW MODERATE INSTABILITY /MLCAPE OF 1500 TO 2000 J/KG/...MODERATE
TO STRONG DEEP LAYER SHEAR /0-6 KM OF 40 TO 55 KT/ AND STEEP
MID-LEVEL LAPSE RATES. THIS ENVIRONMENT SHOULD SUPPORT SUPERCELL
DEVELOPMENT WITH LARGE HAIL AND WIND DAMAGE POSSIBLE WITH THE MORE
INTENSE CORES. IN SPITE OF THE MODEL UNCERTAINTY THE ENVIRONMENT
SHOULD SUPPORT A SEVERE THREAT MAKING AN UPGRADE TO SLIGHT RISK
WARRANTED. THE GREATEST SEVERE THREAT SHOULD EXIST FROM CHILDRESS
SWD TO JUST SOUTH OF SAN ANGELO WHERE THE LOW-LEVEL JET IS FORECAST
TO BECOME ENHANCED DURING THE EARLY EVENING AND THE DRYLINE MAY
BULGE.

...UPPER OH VALLEY/MID-ATLANTIC...
AN UPPER-LEVEL TROUGH WILL MOVE EWD ACROSS SERN CANADA AND THE LOWER
GREAT LAKES TODAY. AT THE SFC... A LOW IS FORECAST TO DEEPEN THIS
AFTERNOON TO THE NORTH OF LAKE ONTARIO WITH A COLD FRONT EXTENDING
SWD FROM THE LOW ACROSS WRN NY AND WRN PA. AHEAD OF THE FRONT...SFC
DEWPOINTS SHOULD BE IN THE UPPER 50S F ALLOWING FOR SOME
DESTABILIZATION TO OCCUR. THUNDERSTORMS SHOULD INITIATE ALONG THE
BOUNDARY WITH CONVECTION MOVING EWD ACROSS PA INTO THE MID-ATLANTIC
REGION DURING THE AFTERNOON. FORECAST SOUNDINGS ACROSS THE SEE TEXT
AREA AT 21Z SHOW SBCAPE VALUES OF 500 TO 1000 J/KG WITH 40 KT OF 0-6
KM SHEAR AND UNIDIRECTIONAL WIND PROFILES. THIS ENVIRONMENT COULD
SUPPORT AN ISOLATED WIND DAMAGE THREAT BUT THE THREAT IS EXPECTED TO
REMAIN MARGINAL DUE TO THE LOWER SFC DEWPOINTS.

...NE KS/NCNTRL MO/SCNTRL IL...
WEST TO NORTHWEST FLOW WILL BE IN PLACE ACROSS THE UPPER MIDWEST
TODAY AS AN UPPER-LEVEL LOW DEVELOPS ACROSS THE SRN PLAINS. AT THE
SFC...A WARM FRONT WILL MOVE NWD ACROSS NERN KS...NCNTRL MO AND SRN
IL TODAY WITH MODERATE DESTABILIZATION POSSIBLY TAKING PLACE ALONG
AND SOUTH OF THE BOUNDARY. THE MODELS AGAIN APPEAR TO BE
OVERESTIMATING BOUNDARY LAYER MOISTURE CONTENT BUT SFC DEWPOINTS
STILL COULD REACH THE UPPER 50S TO NEAR 60 F IN NCNTRL MO THIS
AFTERNOON. THIS COMBINED WITH STEEP LOW-LEVEL LAPSE RATES AND
UNIDIRECTIONAL LOW-LEVEL WINDS MAY BE ENOUGH FOR A WIND DAMAGE
THREAT WITH CELLS THAT CAN INITIATE ALONG THE BOUNDARY THIS
AFTERNOON.

..BROYLES/LEITMAN.. 05/15/2013

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