Monday, May 23, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 231628
SWODY1
SPC AC 231627

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1127 AM CDT MON MAY 23 2011

VALID 231630Z - 241200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
PORTIONS OF CENTRAL IL...CENTRAL IND...NORTHERN OH...AND SOUTHWEST
LOWER MI...

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PORTIONS OF WESTERN AND
NORTHERN OK...SOUTHEAST KS...AND SOUTHWEST MO...

...THERE IS A SLGT RISK OF SVR TSTMS OVER A LARGE AREA FROM THE
SOUTHERN PLAINS...ACROSS THE MID MS AND OH VALLEYS...INTO NY/PA AND
THE MID ATLANTIC REGION...

A VERY COMPLEX CONVECTIVE DAY IS FORECAST ACROSS THE UNITED STATES
TODAY...WITH NUMEROUS AREAS OF SEVERE WEATHER POTENTIAL.

...NY/PA INTO MID ATLANTIC STATES...
A SHORTWAVE TROUGH IS NOTED IN SATELLITE IMAGERY OVER OH/WV. THIS
FEATURE WILL TRACK EASTWARD TODAY AND PROVIDE FOCUS FOR THUNDERSTORM
REDEVELOPMENT DURING MUCH OF THE AFTERNOON. LOW CLOUDS ARE LIMITING
HEATING FROM PA NORTHWARD...BUT EVEN THIS AREA SHOULD BECOME
MARGINALLY UNSTABLE BY LATE AFTERNOON AS CLOUDS BURN OFF AND
DEWPOINTS RISE INTO THE 60S. PRESENT INDICATIONS ARE THAT BAND OF
STRONG/SEVERE STORMS WILL EXTEND FROM CENTRAL PA INTO CENTRAL
VA...WITH MORE ISOLATED INTENSE STORMS FROM THERE SOUTHWARD INTO NC.
DAMAGING WINDS ARE THE MOST LIKELY THREAT OVER THE NORTHERN PORTION
OF THIS AREA...WITH HAIL BECOMING INCREASINGLY POSSIBLE FARTHER
SOUTH WHERE GREATER INSTABILITY WILL EXIST. EVEN A FEW SUPERCELLS
WILL BE POSSIBLE OVER VA/NC AREAS AS EFFECTIVE SHEAR VALUES RANGE
FROM 30-40 KNOTS.

...MID MS AND OH VALLEY...
A LARGE CLUSTER OF THUNDERSTORMS CONTINUES TO INCREASE IN COVERAGE
AND INTENSITY OVER MO. THE LEADING EDGE OF THESE STORMS APPEAR TO
BE ACCELERATING TOWARD THE STL AREA AND INTO AN AIR MASS WHERE RAPID
DESTABILIZATION IS OCCURRING. THIS ACTIVITY APPEARS CLOSELY TIED TO
A SHORTWAVE TROUGH MOVING ACROSS IA/MO...AND A LOW LEVEL WIND MAX
SHOWN IN MULTIPLE MODEL RUNS. THE WIND MAX AND ASSOCIATED STORMS
ARE LIKELY TO TRACK QUICKLY NORTHEASTWARD ACROSS PORTIONS OF
IL/IN/OH THIS AFTERNOON AND EVENING WITH A RISK OF RATHER WIDESPREAD
DAMAGING WIND AND HAIL. STORMS MAY ALSO DEVELOP AHEAD OF THE
PRIMARY CLUSTER OVER NORTHERN IND/NORTHWEST OH AND SPREAD INTO
SOUTHWEST LOWER MI. FOR THESE REASONS...HAVE MAINTAINED AND
ACTUALLY EXPANDED THE MODERATE RISK ACROSS THESE REGIONS.

...CENTRAL/SOUTHERN PLAINS...
ISOLATED THUNDERSTORMS HAVE DEVELOPED NEAR DFW TODAY...AND ARE
EXPECTED TO TRACK EASTWARD THROUGH THE DAY WITH A CONTINUED RISK OF
ISOLATED SEVERE WEATHER. BEHIND THIS ACTIVITY...STRONG HEATING AND
DEWPOINTS IN THE UPPER 60S TO LOWER 70S WILL YIELD AFTERNOON MLCAPE
VALUES OF 4000-5000 J/KG AND A WEAK CAP. A SHORTWAVE TROUGH MOVING
ACROSS WEST TX WILL LIKELY RESULT IN THE DEVELOPMENT A FEW DISCRETE
SUPERCELL THUNDERSTORMS BY MID AFTERNOON OVER WESTERN OK. STORMS
WILL ALSO LIKELY DEVELOP BY EARLY EVENING IN VICINITY OF REMNANT
OUTFLOW BOUNDARIES OVER NORTHERN OK/SOUTHERN KS. BACKING LOW LEVEL
FLOW THROUGH THE EVENING WILL PROMOTE UPDRAFT ROTATION WITH RISK OF
VERY LARGE HAIL AND A FEW TORNADOES THROUGH THE EVENING.
OVERNIGHT... GENERAL MODEL CONCENSUS SUGGESTS STORMS MAY GROW
UPSCALE OVERNIGHT WITH AN MCS TRACKING TO AR WITH A RISK OF HAIL AND
DAMAGING WINDS.

..HART/GRAMS.. 05/23/2011

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