(7/26) WATCH Likely

SEVERE WEATHER TOOLS
WAVE 3 STORM CUTTER HD INTERACTIVE RADAR
WAVE 3 STORM TRACKING TEAM FACEBOOK
WAVE 3 STORM TRACKING TEAM TWITTER
WAVE 3 STORM TRACKING TEAM MOBILE APPS & MORE


A SEVERE THUNDERSTORM OR TORNADO WATCH WILL LIKELY BE ISSUED FOR PORTIONS OF THE WAVE 3 VIEWING AREA THIS AFTERNOON.

STORMS WILL RAPIDLY DEVELOP ACROSS THE AREA THROUGH THE AFTERNOON.  DAMAGING WIND GUSTS WILL BE THE PRIMARY THREAT, BUT HAIL IS ALSO POSSIBLE IN THE STRONGER STORMS.

FROM THE STORM PREDICTION CENTER
DISCUSSION...15Z SFC MESOANALYSIS SHOWS THERMAL GRADIENT ASSOCIATED WITH  DIFFERENTIAL HEATING...AND CORRESPONDING TO DIFFUSE ERN FRINGE OF THICKER CLOUD COVER ON VIS IMAGERY.  THIS ZONE WAS LOCATED FROM SRN IL AND SWRN INDIANA NEWD OVER W-CENTRAL/NRN OH...THEN ENEWD OVER NWRN PA...WHERE IT INTERSECTED WARM FRONT EXTENDING ESEWD OVER S-CENTRAL PA.  WARM FRONT IS EXPECTED TO MOVE NEWD ACROSS CENTRAL/ERN PA THROUGH MID-AFTERNOON.  DIFFERENTIAL-HEATING ZONE WILL MOVE LITTLE AS CLOUDS ERODE WITH EWD EXTENT BUT CONTINUE TO ADVECT OVER AREA FROM W.  VIS IMAGERY ALSO SHOWS MCV MOVING ENEWD ABOUT 35 KT OVER W-CENTRAL IL...ON TRACK TO REACH NRN INDIANA AROUND 22Z...AND PRECEDED BY MESOSCALE ENHANCEMENTS TO DEEP-LAYER FLOW AND MIDLEVEL ASCENT.  GRAVITY WAVE WAS EVIDENT MOVING SEWD OVER SWRN PA...OH/WV BORDER AND CENTRAL KY...BEHIND WHICH STRONGEST SFC HEATING IS OCCURRING FROM NERN OH TO WRN KY.
   
IN LOW LEVELS...CINH EVIDENT IN 12Z PBZ/ILN RAOBS IS BEING REMOVED QUICKLY BY STG DIABATIC HEATING AND BOUNDARY-LAYER MIXING...BELOW PLUME OF ELEVATED MIXED-LAYER AIR THAT CONTRIBUTES STEEP LOW-MIDDLE LEVEL LAPSE RATES.  WITH SFC DEW POINTS COMMONLY 70S F...NET RESULT WILL BE PRECONVECTIVE MLCAPE STRENGTHENING TO 3500-5000 J/KG RANGE OVER BROAD SWATH OF WARM SECTOR...BETWEEN WARM FRONT AND DIFFERENTIAL-HEATING ZONE.  SUCH STG-EXTREME BUOYANCY ATOP WELL-MIXED SUBCLOUD LAYERS...AMIDST NEARLY UNIDIRECTIONAL/WLY-WSWLY DEEP-LAYER WINDS...SUGGEST POTENTIAL FOR ONE OR MORE FORWARD-PROPAGATIONAL TSTM CLUSTERS WITH ORGANIZED/AGGREGATE COLD POOLS ENHANCING SVR WIND RISK. THIS MAY OCCUR WITH DEVELOPMENT NOW OVER LE AS IT ENCOUNTERS DESTABILIZING AIR MASS NEAR WARM FRONT AND SRN-SHORE LAKE BREEZE...AS WELL AS SUBSEQUENT DEVELOPMENT INVOF DIFFERENTIAL-HEATING ZONE AND AHEAD OF MCV OVER PORTIONS INDIANA/OH. EFFECTIVE SHEAR INCREASES WITH NEWD EXTENT TOWARD AND OVER WARM FRONT...VALUES REACHING 40-50 KT IN NWRN PA WHERE EFFECTIVE SRH ALSO IS MAXIMIZED.  THIS SUGGESTS RELATIVE MAX IN SUPERCELL/TORNADO RISK ALSO MAY EXIST INVOF WARM FRONT...SHIFTING EWD/NEWD WITH THAT BOUNDARY.