AREAS AFFECTED...CNTRL/SWRN OH...ERN/CNTRL/NRN IND...FAR NERN
IL...CNTRL/NRN KY
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 252048Z - 252245Z
PROBABILITY OF WATCH ISSUANCE...20 PERCENT
SUMMARY...AN ISOLATED THREAT FOR SVR THUNDERSTORMS MAY CONDITIONALLY
EXIST INTO THE EVENING HOURS. WHILE CONVECTIVE TRENDS WILL CONTINUE
TO BE MONITORED...WW ISSUANCE IS CURRENTLY UNLIKELY.
DISCUSSION...VISIBLE SATELLITE IMAGES AND SURFACE OBSERVATIONS
INDICATE A HOT/DEEPLY-MIXED BOUNDARY LAYER OVERTAKING A WARM SECTOR
WHOSE NERN BOUND IS DELINEATED BY A WARM FRONT ARCING FROM NEAR
SOUTH BEND IND TO W OF DAYTON OH AND TO E OF JACKSON KY. DEEP
BOUNDARY-LAYER CIRCULATIONS AMIDST THE HOT/DEEPLY-MIXED BOUNDARY
LAYER ARE SUPPORTING A BROAD FIELD OF HIGH-BASED CUMULUS DEVELOPMENT
AMIDST SFC TEMPERATURES OVER 100F AND STEEP LOW-LEVEL LAPSE RATES.
WHILE DEEPER CONVECTION WILL STRUGGLE TO EVOLVE WITHIN THE CORE OF
THIS HOT AIR MASS...CUMULUS APPEARS TO EXHIBIT MORE VERTICAL
DEVELOPMENT -- WITH A FEW DEEPER CONVECTIVE PLUMES -- AT THE LEADING
EDGE OF THE HOT AIR MASS FROM NERN IL ACROSS NRN/CNTRL IND INTO NWRN
KY. ADDITIONAL POCKETS OF SWELLING CUMULUS ARE NOTED IN THE
CINCINNATI AREA AND FARTHER EAST ACROSS N-CNTRL/ERN KY. ALSO OF
NOTE...THE LEADING EDGE OF THE HOT AIR MASS IS MARKED BY A WIND
SHIFT AXIS ACROSS NW/CNTRL IND AND A WELL-DEFINED 0.5-DEGREE
RADAR-REFLECTIVITY FINE LINE ARCING FROM CNTRL TO SRN IND PER
INDIANAPOLIS WSR-88D DATA.
ISOLATED THUNDERSTORMS MAY EVOLVE FROM THE CUMULUS DURING THE NEXT
FEW HOURS...WITH THE THREAT EXPANDING EWD/NEWD IN CONJUNCTION WITH
THE MOTION OF THE WARM FRONT. BETWEEN THE LEADING EDGE OF THE HOT
AIR MASS AND THE WARM FRONT...ENHANCED LOW-LEVEL MOISTURE WITH SFC
DEWPOINTS IN THE LOWER/MIDDLE 70S AMIDST TEMPS IN THE LOWER/MIDDLE
90S IS SUPPORTING UPWARDS OF 2500-3500 J/KG OF MLCAPE PER MODIFIED
NAM/RAPID-REFRESH FORECAST SOUNDINGS. THIS MAY SUPPORT A FEW INTENSE
UPDRAFTS...WHICH MAY BE ENHANCED IF THEY INTERACT WITH 30-40 KT OF
EFFECTIVE BULK SHEAR WITHIN THE FRONTAL ZONE -- ENHANCED BY MODEST
LOW-LEVEL DIRECTIONAL SHEAR PER WILMINGTON VWP DATA. A CONDITIONAL
THREAT FOR SVR WINDS -- AIDED BY DCAPE OVER 1000 J/KG -- AND SVR
HAIL WILL EXIST WITH SUSTAINED STORMS. HOWEVER...GIVEN THE PRESENCE
OF A MID-LEVEL RIDGE ACROSS THE REGION...RELATIVELY WARMER AIR ALOFT
AND THE LACK OF STRONGER DEEP FORCING FOR ASCENT SHOULD KEEP STORM
COVERAGE LIMITED.
..COHEN/HART.. 07/25/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...RLX...CLE...JKL...ILN...LMK...IWX...IND...LOT...
LAT...LON 37418532 37928600 39198625 40348673 41108780 41638810
41938760 41718636 40978388 40248301 38898239 37808204
37238253 37128352 37278442 37418532
