SPC AC 250541
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1241 AM CDT SUN JUL 25 2010
VALID 251200Z - 261200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM SRN PARTS OF THE OH VALLEY
THROUGH THE MID-ATLANTIC...
...SYNOPSIS...
UPPER TROUGH WILL CONTINUE THROUGH ERN CANADA AND THE NERN STATES
SUNDAY ACCOMPANIED BY A COLD FRONT THAT WILL MOVE OFF THE NE U.S.
COAST AROUND MID-DAY. TRAILING PORTION OF FRONT WILL EXTEND SWWD
THROUGH THE OH AND LOWER MS VALLEYS AND INTO OK. PRE-FRONTAL
CONVECTIVE BOUNDARY IS LOCATED FROM PA WWD THROUGH SRN MO AND OK.
THIS BOUNDARY WILL PERSIST AND SETTLE SLOWLY SWD. A STRONG MCV AND
ATTENDANT OUTFLOW BOUNDARY OVER IL WILL CONTINUE EWD THROUGH THE OH
VALLEY...REACHING THE MID ATLANTIC SUNDAY AFTERNOON. UPPER LOW
CIRCULATION WILL DRIFT SLOWLY WNWWD THROUGH TX.. AND REMNANTS OF
BONNIE WILL CONTINUE INTO THE LOWER MS VALLEY.
...SRN PORTIONS OF THE OH VALLEY THROUGH MID ATLANTIC REGION...
ONE POTENTIAL ZONE OF SEVERE STORMS COULD DEVELOP IN ASSOCIATION
WITH PROGRESSIVE MCV NOW LOCATED ACROSS CNTRL IL. THIS FEATURE WILL
ADVANCE THROUGH PRE-FRONTAL WARM SECTOR. WRN END OF SLIGHT RISK
CORRESPONDS TO WHERE THIS MCV WILL LIKELY BE SUNDAY MORNING. THE
ATMOSPHERE SHOULD DESTABILIZE DOWNSTREAM ACROSS SRN PARTS OF THE OH
VALLEY INTO THE MID-ATLANTIC REGION WHERE DIABATIC WARMING OF THE
MOIST BOUNDARY LAYER WILL BOOST MLCAPE TO 2000 J/KG. WEAK CAP AND
CONVERGENCE ALONG RESIDUAL OUTFLOW BOUNDARIES AUGMENTED BY THE
PROGRESSIVE MCV SHOULD PROMOTE THUNDERSTORMS DEVELOPING DURING THE
AFTERNOON AND SPREADING ESEWD WITH TIME. STRONGER FLOW ALOFT WILL
DEVELOP SWD INTO THE MID ATLANTIC ALONG BASE OF NERN U.S. UPPER
TROUGH. UNIDIRECTIONAL 35-45 KT BULK SHEAR IS EXPECTED ACROSS MUCH
OF MID-ATLANTIC WARM SECTOR WITH WEAKER SHEAR FARTHER WEST ACROSS
KY. A FEW SUPERCELLS...LINE SEGMENTS AND CLUSTERS WILL BE POSSIBLE
AS STORMS DEVELOP SEWD. ISOLATED DAMAGING WIND IS EXPECTED TO BE THE
PRIMARY THREAT.
OTHER STORMS COULD ALSO DEVELOP FARTHER NORTH IN ASSOCIATION WITH
THE SEWD ADVANCING COLD FRONT. HOWEVER...ANY SEVERE THREAT WITH THIS
FEATURE WILL DEPEND ON HOW MUCH OF THE WARM SECTOR IS OVERTURNED BY
STORMS DEVELOPING FARTHER SE IN ASSOCIATION WITH OUTFLOW BOUNDARIES
AND MCV.
...SRN PLAINS THROUGH LOWER MS VALLEY...
DIABATIC WARMING OF MOIST WARM SECTOR WILL RESULT IN 1500-2500 J/KG
MLCAPE. STORMS WILL ONCE AGAIN DEVELOP ALONG STALLED FRONT AND
RESIDUAL OUTFLOW BOUNDARIES ACROSS OK/KS AND IN ASSOCIATION WITH THE
UPPER LOW AND REMNANTS OF BONNIE FARTHER SOUTH AND EAST. MID-LEVEL
LAPSE RATES WILL BE SOMEWHAT STEEPER IN VICINITY OF THE UPPER LOW
ACROSS CNTRL OR N-CNTRL TX SUGGESTING THESE STORMS COULD PRODUCE
SOME MARGINALLY SEVERE HAIL. OTHERWISE...ISOLATED STRONG DOWNBURST
WINDS WILL BE POSSIBLE. WEAK VERTICAL SHEAR AND A MODEST
THERMODYNAMIC ENVIRONMENT INDICATE STORMS WILL HAVE LIMITED
ORGANIZATIONAL AND SEVERE POTENTIAL.
...NRN ND...
A SWLY LOW LEVEL JET WILL STRENGTHEN OVER THE CNTRL AND NRN HIGH
PLAINS WHILE AN UPPER TROUGH DROPS SEWD THROUGH S-CNTRL CANADA.
THETA-E ADVECTION AND ISENTROPIC LIFT ALONG NOSE OF LOW LEVEL JET
MAY CONTRIBUTE TO LATE NIGHT THUNDERSTORM DEVELOPMENT ACROSS NRN ND.
STORMS WILL BE ELEVATED...BUT STEEP LAPSE RATES AND MODEST
INSTABILITY WILL RESULT IN A THREAT FOR ISOLATED MARGINALLY SEVERE
HAIL.
..DIAL/DEAN.. 07/25/2010
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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