SWODY1
SPC AC 081937
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0237 PM CDT THU JUL 08 2010
VALID 082000Z - 091200Z
...NO SVR TSTM AREAS FORECAST...
SEVERAL CHANGES HAVE BEEN MADE FOR THE 20Z OUTLOOK. THE FIRST IS TO
ADD A 5 PERCENT HAIL PROBABILITY ACROSS PARTS OF ERN ND AND NW MN
WHERE A POCKET OF MODERATE INSTABILITY HAS DEVELOPED THIS AFTERNOON.
OBJECTIVE ANALYSIS SHOWS ABOUT 25 KT OF DEEP LAYER SHEAR ACROSS ERN
ND AND NW MN WITH 500 MB TEMPS AROUND -14 C. THIS SHOULD SUPPORT A
MARGINAL HAIL THREAT THROUGH LATE AFTERNOON. THE SECOND CHANGE TO
THE OUTLOOK IS TO ADD A 5 PERCENT HAIL PROBABILITY ALONG AND JUST TO
THE EAST OF THE FRONT RANGE IN ECNTRL CO. OBJECTIVE ANALYSIS SHOWS
MODERATE INSTABILITY IN PLACE WITH 700 TO 500 MB LAPSE RATES
ESTIMATED AT 7.0 TO 8.0 C/KM. IN ADDITION...THE PLATTEVILLE CO
PROFILER SHOWS ABOUT 25 KT OF 0-6 KM SHEAR. THIS ENVIRONMENT SHOULD
SUPPORT A MARGINAL HAIL THREAT THIS AFTERNOON...SEE MCD 1227.
..BROYLES.. 07/08/2010
.PREV DISCUSSION... /ISSUED 1113 AM CDT THU JUL 08 2010/
...SOUTH TX...
TD 2 CURRENTLY APPROACHING BRO AND WILL BE MOVING INLAND THIS
AFTERNOON. CURRENT SHEAR PROFILES ARE STILL MARGINALLY FAVORABLE IN
THE NERN QUAD OF THE CIRCULATION FOR ISOLATED TORNADOES GIVEN THE
VERY TROPICAL AIR MASS. HOWEVER IT NOW LOOKS LIKE THE NAM SOLUTION
OF INCREASING THE 850MB WINDS TO 50KT ONSHORE LATER THIS AFTERNOON
IS TOO AGGRESSIVE GIVEN THE VERY LIMITED TIME THE CIRCULATION WILL
REMAIN OVER THE WATER AND CURRENT LACK OF INTENSIFICATION. THUS
WILL NOT UPGRADE ON THIS OUTLOOK BUT CONTINUE TO MONITOR FOR A NOW
UNEXPECTED INCREASE IN SHEAR SUFFICIENT FOR A GREATER THREAT.
...VA/CAROLINAS...
BROAD UPPER LOW OFF THE MID ATLANTIC COAST IS MOVING
SLOWLY WESTWARD WITH INCREASING NORTHERLY MID/UPPER LEVEL
FLOW. SURFACE TEMPERATURES IN THE 90S WILL YIELD MLCAPE VALUES
AROUND 1000 J/KG WITH LITTLE CINH AS HIGHER PWATS ARE SPREADING WWD
ACROSS THE ERN NC/SRN VA. SCATTERED THUNDERSTORMS ARE
LIKELY TO FORM IN THIS REGION WITH THE STRONGEST CELLS CAPABLE OF
STRONG DOWNBURST WINDS. THREAT STILL APPEARS TO BE MARGINAL FOR AN
UPGRADE.
..MO/IL/IN/OH/MI...
LITTLE CHANGE IN THINKING FROM PREVIOUS OUTLOOK IN THIS AREA EXCEPT
CLOUD COVER SPREADING EWD ACROSS LWR MI...WILL LIMIT ANY THREAT
THERE TO SERN CORNER WHERE SUFFICIENT HEATING IS OCCURRING PRIOR TO
THE ARRIVAL OF THE COLD FRONTAL CLOUDINESS.
LATEST SURFACE ANALYSIS SHOWS THE COLD FRONT EXTENDING FROM LOWER
MI...ACROSS IL/MO INTO CENTRAL OK. THIS FRONT WILL MOVE SLOWLY
SOUTHEASTWARD TODAY AND PROVIDE THE FOCUS FOR SCATTERED SHOWERS AND
THUNDERSTORMS. THE FRONT HAS GENERALLY OUTRUN THE STRONGER MID
LEVEL FLOW...WITH RATHER WEAK DEEP LAYER EFFECTIVE SHEAR VALUES IN
THE WARM SECTOR. HOWEVER...THE COMBINATION OF A VERY MOIST
THERMODYNAMIC PROFILE /PWAT VALUES OVER 2 INCHES/ AND AFTERNOON
MLCAPE VALUES OF 1500-2000 J/KG INDICATE THE RISK OF A FEW INTENSE
PULSE OR WEAKLY ORGANIZED MULTICELL THUNDERSTORMS. LOCALLY DAMAGING
WINDS ARE THE MAIN THREAT.
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