SPC AC 230600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT FRI JUL 23 2010
VALID 231200Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CNTRL AND NRN PLAINS
EWD THROUGH THE GREAT LAKES...OH VALLEY AND NERN STATES...
...THERE IS A SLGT RISK OF SVR TSTMS OVER SRN FL...
...SYNOPSIS...
PROGRESSIVE ZONAL PATTERN WILL REMAIN ACROSS THE NRN THIRD OF THE
COUNTRY. SIGNIFICANT SHORTWAVE TROUGH EMBEDDED WITHIN THIS REGIME
WILL MOVE INTO THE NRN PLAINS FRIDAY AFTERNOON AND UPPER MS VALLEY
FRIDAY NIGHT. SURFACE LOW WILL DEVELOP WITHIN ZONE OF DPVA
ACCOMPANYING THE UPPER TROUGH AND SHIFT EWD THROUGH SD. WARM FRONT
WILL EXTEND FROM THE SURFACE LOW INTO THE UPPER MS VALLEY...WHILE
TRAILING COLD FRONT ADVANCES SEWD THROUGH SD AND NEB. PRE-FRONTAL
CONVERGENCE BOUNDARY WILL PERSIST FROM WRN KS NEWD THROUGH NEB.
FARTHER EAST ANOTHER SIGNIFICANT SHORTWAVE TROUGH WILL CONTINUE
ENEWD OVER TOP OF UPPER RIDGE AXIS THROUGH ONTARIO AND THE NRN GREAT
LAKES. CONVECTIVELY REINFORCED E-W BAROCLINIC ZONE WILL PERSIST FROM
THE GREAT LAKES INTO THE NERN STATES.
...CNTRL AND NRN PLAINS THROUGH UPPER MS VALLEY AREA...
BOUNDARY LAYER WINDS WILL RETURN TO SELY ACROSS NEB AND SD EAST OF
DEVELOPING SURFACE LOW AND ADVECT UPPER 60S DEWPOINTS NWD BENEATH
PLUME OF STEEPER LAPSE RATES SPREADING EWD OFF THE HIGHER TERRAIN.
THESE PROCESSES AND DIABATIC WARMING WILL RESULT IN 2000-3000 J/KG
MLCAPE OVER PORTIONS OF CNTRL AND NRN PLAINS AND MID-UPPER MS
VALLEY. A FEW STORMS...PRIMARILY ELEVATED...MAY BE ONGOING FROM ERN
MT INTO THE WRN DAKOTAS WITHIN ZONE OF DEEP ASCENT ACCOMPANYING THE
SHORTWAVE TROUGH. THIS ACTIVITY COULD POSE A MARGINAL RISK FOR HAIL.
PRIMARY ZONE OF THUNDERSTORM INITIATION WILL OCCUR FARTHER SOUTH
WITHIN ZONE OF FORCING EAST OF SURFACE LOW AND ALONG THE WARM FRONT.
OTHER STORMS MAY ALSO DEVELOP IN ASSOCIATION WITH THE SEWD ADVANCING
COLD FRONT. INITIAL STORMS WILL LIKELY BE SUPERCELLULAR IN NATURE
GIVEN STRONG DEEP SHEAR AND HODOGRAPHS SUPPORTIVE OF LOW-LEVEL
MESOCYCLONES EAST. VERY LARGE HAIL AND ISOLATED TORNADOES WILL BE
THE INITIAL MAIN THREATS. DURING THE EVENING...ACTIVITY SHOULD
EVOLVE INTO AN MCS WITH INCREASING DAMAGING WIND POTENTIAL TOWARD
THE UPPER MS VALLEY SUPPORTED BY AMPLE MOISTURE AND STRENGTHENING
LOW-LEVEL JET.
...OH VALLEY THROUGH LOWER GREAT LAKES AND NERN STATES...
A FEW STORMS MAY STILL BE ONGOING IN VICINITY OF BAROCLINIC ZONE
OVER THE GREAT LAKES EARLY FRIDAY....BUT ARE EXPECTED TO DIMINISH
THROUGH THE MORNING. OTHER STORMS WILL CONTINUE INTO THE NERN STATES
WITHING ZONE OF WARM ADVECTION ACCOMPANYING EWD MIGRATING LOW LEVEL
JET. IN WAKE OF THE MORNING ACTIVITY THE ATMOSPHERE WILL DESTABILIZE
INITIALLY OVER THE OH VALLEY AND SRN GREAT LAKES AS THE BOUNDARY
LAYER WARMS...THEN INTO THE NERN STATES AS RICHER MOISTURE IS
ADVECTED EWD. STORMS MAY GRADUALLY INCREASE IN COVERAGE AND
INTENSITY OVER THE NERN U.S PROMOTED BY INCREASINGLY UNSTABLE INFLOW
FROM WARM SECTOR.
GIVEN TENDENCY FOR LOW LEVEL JET TO SHIFT EAST OF OH VALLEY AND
GREAT LAKES ALONG WITH MODEST HEIGHT RISES IN WAKE OF SHORTWAVE
TROUGH MOVING THROUGH ONTARIO...DEEP FORCING FOR ASCENT WILL BE
SOMEWHAT LIMITED DURING THE DAY OVER THE OH VALLEY/GREAT LAKES
REGION. THIS ALONG WITH MODEST VERTICAL SHEAR COULD BE LIMITING
FACTORS FOR A MORE ROBUST SEVERE THREAT. PRESENCE OF THE E-W
CONVECTIVELY ENHANCED BOUNDARY AND WEAK CAP COULD SUPPORT A FEW
STORMS DEVELOPING DURING THE AFTERNOON. ANY STORMS THAT DEVELOP WILL
BE EMBEDDED WITHIN MODERATE 30-40 KT DEEP LAYER FLOW WITH ISOLATED
DAMAGING WIND GUSTS THE MAIN THREAT. OTHER STORMS MAY INCREASE FROM
THE WEST ACROSS NRN IL INTO THE UPPER GREAT LAKES OVERNIGHT WITHIN
ZONE OF LIFT ASSOCIATED WITH EWD MIGRATING SWLY LOW LEVEL JET
ATTENDING SHORTWAVE TROUGH MOVING INTO THE UPPER MS VALLEY. THIS
ACTIVITY COULD ALSO POSE A RISK FOR ISOLATED DAMAGING WIND.
...S FL...
CENTER OF TROPICAL STORM BONNIE IS FORECAST BY NHC TO MOVE NEAR THE
SRN TIP OF FL LATE THIS AFTERNOON AND EMERGE OVER THE ERN GULF
TONIGHT. THIS WILL PUT THE SRN FL PENINSULA IN THE NERN QUADRANT FOR
A THREAT OF ISOLATED TORNADOES THIS EVENING. WILL INTRODUCE A 5%
PROBABILITY FOR ISOLATED TORNADOES MAINLY FOR LATE THIS AFTERNOON
AND EVENING WITH STORMS DEVELOPING WITHIN THE OUTER BANDS OF BONNIE.
..DIAL/SMITH.. 07/23/2010
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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