DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 281256
SWODY1
SPC AC 281254

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 AM CDT THU JUN 28 2012

VALID 281300Z - 291200Z

...THERE IS A SLGT RISK OF SVR TSTMS ...

...SYNOPSIS...
EXPANSIVE ANTICYCLONE NOW EXTENDING FROM THE SRN RCKYS TO THE LWR OH
VLY WILL FURTHER ELONGATE W-E THIS PERIOD AS CNTRL PORTION
TEMPORARILY IS SUPPRESSED BY PROGRESSIVE SHORTWAVE TROUGH CROSSING
MB. THE MB SYSTEM SHOULD REACH JAMES BAY BY 12Z FRI AS WEAK
TROUGHING CONTINUES OVER THE PACIFIC NW...AND LOW NOW OVER NB MOVES
NE INTO NEWFOUNDLAND. FARTHER S...A SERIES OF WEAKER DISTURBANCES
WILL PERSIST IN ARC OF ENHANCED FLOW SKIRTING IMMEDIATE N SIDE OF
RIDGE. THE MOST SIGNIFICANT OF THESE IMPULSES...NOW OVER ERN SD/NE
NEB...SHOULD REACH LWR MI THIS EVE AND THE MID ATLANTIC CST EARLY
FRI.

FEATURES WILL REMAIN WEAK AT THE SFC. NRN PART OF COLD FRONT NOW
EXTENDING FROM THE UPR GRT LKS TO THE CNTRL PLNS SHOULD CONTINUE
STEADILY E/SE ACROSS THE NRN APPALACHIANS/MID ATLANTIC REGION BY THE
END OF THE PERIOD. THE TRAILING WRN PART OF THE
BOUNDARY...HOWEVER...LIKELY WILL BECOME QSTNRY FROM SRN NEB/NW KS TO
NRN IL/IND. THE FRONT WILL TO SOME EXTENT SERVE AS A FOCUS FOR
POTENTIALLY STRONG TO SVR TSTMS THROUGH THE PERIOD. BUT STORM
COVERAGE WILL BE LIMITED BY CONTINUING PRESENCE OF DEEP/EXPANSIVE
EML.

...LWR MI/OH VLY INTO PA/NY TODAY THROUGH EARLY FRI...
CAP ASSOCIATED WITH VERY WARM EML...AND RELATIVELY DRY LOW LVL
AIR...SUGGESTS THAT LIKELIHOOD FOR ORGANIZED SVR TSTMS WILL REMAIN
LOW ALONG/AHEAD OF COLD FRONT FROM LWR MI S/SE INTO THE OH VLY
TODAY. HOWEVER...A GREATER POTENTIAL FOR DEVELOPMENT MAY BE
REALIZED TNGT THROUGH EARLY FRI ALONG THE NE FRINGE OF THE EML.

ELONGATION OF UPR RIDGE WILL CARRY ERN EDGE OF THE EML WELL BEYOND
ITS USUAL RANGE...DISPLACING IT INTO THE UPR OH VLY/WRN MID ATLANTIC
REGION. WHILE ASSOCIATED WARM MID LVL TEMPS SHOULD PROHIBIT
SFC-BASED STORM DEVELOPMENT AHEAD OF THE FRONT...FRONTAL
UPLIFT/POST-FRONTAL WAA/MOISTURE TRANSPORT MAY SUPPORT ELEVATED
CONVECTION IN THE WAKE OF THE BOUNDARY. THESE STORMS COULD PRODUCE
SVR HAIL AND POSSIBLY DMGG WIND GIVEN STEEP MID LVL LAPSE
RATES/INCREASING MOISTURE ALOFT. THE MOST LIKELY AREA FOR SUCH
DEVELOPMENT WILL BE OVER THE LK ERIE REGION THIS EVE...WHERE ASCENT
WILL BE ENHANCED BY CONTINUED E/ESE ADVANCE OF NEB/SD IMPULSE. THE
STORMS COULD SPREAD E/SE INTO ERN PA/MD BY 12Z FRI.

...CNTRL PLNS TO MID MS VLY TODAY/TNGT...
STALLING SFC FRONT AND ASSOCIATED OUTFLOW BOUNDARIES WILL SERVE TO
FOCUS STORM DEVELOPMENT LATER TODAY FROM THE CNTRL HI PLNS EWD INTO
SRN NEB/NRN KS IN RESPONSE TO STRONG SFC HEATING. THE STORMS SHOULD
BE HIGH-BASED/MULTICELLULAR GIVEN EXPECTED WIND/THERMODYNAMIC
ENVIRONMENT...AND COULD YIELD ISOLD DMGG WIND GUSTS. SOME POTENTIAL
ALSO WILL EXIST FOR COLD-POOL MERGERS THAT MIGHT ENHANCE SVR
POTENTIAL ON A SOMEWHAT LARGER SCALE OVER NE CO/SW NEB/NW KS THIS
EVE. HOWEVER...WEAK DEEP SHEAR AND MODEST NATURE OF LARGE SCALE
ASCENT/NOCTURNAL LLJ SHOULD LIMIT DEGREE/EXTENT OF SVR THREAT.

FARTHER E...OVER IA/WI AND NRN IL...STOUT EML SHOULD PROHIBIT
SFC-BASED STORM DEVELOPMENT ALONG THE FRONT...DESPITE PRESENCE OF
MORE SUBSTANTIAL BOUNDARY LAYER MOISTURE RELATIVE TO POINTS W AND E.
HOWEVER...AREAS OF MOISTURE WITHIN AND ABOVE THE LOWEST PORTION OF
THE EML MAY YIELD SCTD AREAS/SHORT LINES OF ACCAS/HIGH-BASED STORMS
THROUGH THE DAY AHEAD OF NEB/SD UPR IMPULSE. ANY SUSTAINED STORMS
THAT DO FORM IN THIS ENVIRONMENT COULD PRODUCE SVR HAIL/LOCALLY DMGG
WIND GIVEN STEEP MID LVL LAPSE RATES. BUT THE LIKELIHOOD FOR
SUSTAINED STORMS APPEARS TOO LOW ATTM TO WARRANT UPGRADE TO
CATEGORICAL SLIGHT RISK.

..CORFIDI/GARNER.. 06/28/2012

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