SWODY1
SPC AC 031248
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0748 AM CDT TUE MAY 03 2011
VALID 031300Z - 041200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL
APPALACHIANS AND MID ATLANTIC STATES...
...SYNOPSIS...
OZARKS SHORTWAVE IMPULSE EXPECTED TO CONTINUE ENE INTO THE OH AND TN
VLYS TODAY...PHASING WITH NRN STREAM DISTURBANCE NOW OVER WI. THE
RESULTING LARGER SCALE TROUGH SHOULD ASSUME A NEARLY NEUTRAL TILT BY
THE END OF THE PERIOD...AND EXTEND FROM LK HURON TO THE SRN
APPALACHIANS.
AT LWR LVLS...SFC WAVE NOW OVER WV SHOULD REMAIN ELONGATED BUT
SOMEWHAT DEEPEN AS IT MOVES NEWD. THE MAIN CENTER SHOULD REACH ERN
PA BY EVE...WHILE TRAILING COLD FRONT CONTINUES E TO THE ERN SLOPES
OF THE CNTRL/SRN APPALACHIANS. THE LOW SHOULD CONTINUE NE INTO
CNTRL/NRN NEW ENGLAND TONIGHT/EARLY WED AS COLD FRONT MOVES OFF THE
MID ATLANTIC CST. DIFFUSE WARM FRONT NOW OVER NRN MD AND PA SHOULD
REFORM NWD INTO ERN NY/CNTRL NEW ENG LATER TODAY...ALLOWING A NARROW
CORRIDOR OF MODIFIED GULF AIR TO SPREAD NNE ACROSS THE SUSQUEHANNA
AND DELAWARE RVR VLYS.
...CNTRL APPALACHIANS AND ADJACENT PIEDMONT...
BROAD BAND OF POST-COLD FRONTAL SHOWERS/EMBEDDED TSTMS NOW EXTENDING
FROM PARTS OF THE LWR MS AND TN VLYS NNE INTO OH LIKELY WILL PERSIST
AND SHIFT EWD WITH THE FRONT THROUGH THE PERIOD. WHILE AMPLE
UNIDIRECTIONAL CLOUD LAYER FLOW WILL BE PRESENT FOR
ORGANIZED/SUSTAINED STORMS...WEAK ELEVATED INSTABILITY SHOULD KEEP
ACTIVITY FROM POSING A SVR WEATHER THREAT.
MEANWHILE...CONTINUED EWD MOTION OF OZARKS UPR IMPULSE SHOULD FOSTER
GRADUAL STRENGTHENING OF WV/PA SFC WAVE AND ASSOCIATED SSWLY LLJ
ALONG THE ERN SLOPES OF THE APPALACHIANS. WHILE SATELLITE AND SFC
OBS SHOW A RELATIVELY DRY POCKET OF AIR CONTINUING TO RESIDE OVER
ERN NC AND ADJACENT REGIONS...THE LLJ SHOULD ALLOW MORE SUBSTANTIAL
MOISTURE /PW AOA 1.25 INCHES/ TO CONTINUE SPREADING NNE AHEAD OF SFC
WAVE. COUPLED WITH SFC HEATING...THIS SHOULD YIELD POCKETS OF
MODERATE INSTABILITY WITH SBCAPE OF 1500 TO PERHAPS 2000 J/KG OVER
PARTS OF VA...ERN WV...MD AND SRN/ERN PA. RELATIVELY WEAK MID LVL
LAPSE RATES SHOULD...HOWEVER...LIMIT OVERALL DEGREE OF INSTABILITY.
CONVERGENCE INVOF THE SFC LOW SHOULD FOSTER TSTM DEVELOPMENT BY
EARLY-MID AFTN OVER PARTS OF PA/MD AND VA/WV. DEVELOPMENT MAY OCCUR
A BIT LATER SWD ALONG COLD FRONT INTO THE WRN CAROLINAS AND GA.
GRADUAL STRENGTHENING OF SWLY MID/UPR LVL FLOW WITH APPROACH OF UPR
TROUGH EXPECTED TO SHOULD ENABLE A FEW SUSTAINED
STORMS...SUPERCELLS...AND BROKEN LINE SEGMENTS. THESE MAY CONTAIN
LOCALLY DMGG WINDS AND...ESPECIALLY ALONG/AHEAD OF SFC LOW TRACK IN
ERN WV/CNTRL MD AND PA...POSSIBLE TORNADOES.
DESPITE CONTINUED INCREASE IN MID/UPR LVL FLOW...THE OVERALL SVR
WEATHER THREAT SHOULD DIMINISH BY LATE EVE AS LOW LVL INSTABILITY
WANES.
...ERN AL INTO GA/WRN SC...
MODERATE INSTABILITY WILL DEVELOP AHEAD OF COLD FRONT CROSSING THE
SRN APPALACHIAN REGION THIS AFTN. BUT RELATIVELY WEAK MID LVL LAPSE
RATES AND MORE MODEST WIND FIELD COMPARED TO POINTS FARTHER N
SUGGEST THAT MULTICELLS WILL BE THE PRIMARY STORM MODE. WHILE
STRONG WIND GUSTS AND MARGINALLY SVR HAIL MAY OCCUR...ANY SVR THREAT
SHOULD REMAIN ISOLD AND/OR OF LIMITED DURATION.
..CORFIDI/ROGERS.. 05/03/2011
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