SWODY1
SPC AC 161253
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0753 AM CDT WED MAY 16 2007
VALID 161300Z - 171200Z
..THERE IS A SLGT RISK OF SVR TSTMS OVER THE MID ATLANTIC STATES
AND SRN NEW ENGLAND...
..SYNOPSIS...
GRT LKS TROUGH EXPECTED TO FURTHER AMPLIFY AS ADDITIONAL SHORTWAVE
IMPULSES DROP SE ACROSS THE NRN PLNS/UPR MS VLY. AT THE SAME
TIME...GRT BASIN/RCKYS RIDGE EXPECTED TO EXPAND E INTO THE HI PLNS
AS SEVERAL WEAK DISTURBANCES UNDERCUT IT OVER THE SWRN DESERTS.
AT LWR LEVELS...LOW NOW NEAR ROC SHOULD REDEVELOP SLIGHTLY S OF E
TODAY...REACHING THE PVD AREA THIS EVENING. THE SYSTEM LIKELY WILL
WEAKEN SOMEWHAT AS PATTERN ONCE AGAIN KEEPS STRONGEST DEEP FORCING
FOR ASCENT DISPLACED WELL TO THE WEST...CLOSER TO AMPLIFYING UPR
TROUGH. COLD FRONT TRAILING SW FROM THE LOW SHOULD CLEAR THE MID
ATLANTIC CST EARLY TONIGHT.
..SRN NEW ENGLAND TO NC...
SUNSHINE WILL PREVAIL AHEAD OF COLD FRONT APPROACHING THE PIEDMONT
AND CSTL PLNS OF THE MID ATLANTIC STATES AND SRN NEW ENGLAND TODAY.
WHILE WARM SECTOR MOISTURE WILL BE MEAGER BY MID-MAY STANDARDS...
HEATING SHOULD SUFFICIENTLY STEEPEN LOW LEVEL LAPSE RATES TO YIELD
SBCAPE AOA 500 J/KG. COUPLED WITH WEAKLY CONVERGENT PATTERN AHEAD
OF FRONT AND SOMEWHAT DIFFLUENT NATURE OF HI-LVL FLOW...EXPECT
DEVELOPMENT OF STORMS ALONG/AHEAD OF FRONT BY EARLY AFTERNOON.
DESPITE LIMITED INSTABILITY...PRESENCE OF 40+ KT DEEP UNIDIRECTIONAL
SWLY SHEAR...MODERATE TO STRONG MEAN FLOW AND COMPARATIVELY LARGE
LOW-LEVEL T/TD SPREADS SUGGEST A DECENT LIKELIHOOD FOR UPSCALE
DEVELOPMENT OF CONVECTION INTO SHORT LINES/BANDS...WITH AN ATTENDANT
THREAT FOR HIGH WIND. A SUSTAINED STORM/POSSIBLE SUPERCELL OR TWO
COULD ALSO FORM IMMEDIATELY AHEAD OF SFC LOW IN MASSACHUSETTS AS
STATIONARY FRONT EXTENDING E FROM LOW SHOULD BE FAVORABLY-ORIENTED
TO ALLOW STORM MOTION ALONG IT.
MOST OF THE STORMS LIKELY WILL HAVE WEAKENED AND/OR MOVED OFFSHORE
BY EVENING. ISOLATED STRONG ACTIVITY...HOWEVER...COULD PERSIST
INTO EARLY TONIGHT IN WARMER BUT MORE WEAKLY-SHEARED ENVIRONMENT
OVER SE VA/NC.
..NC SW TO CNTRL GULF CST...
ANOTHER DAY OF SCTD STRONG PULSE STORMS IS FORECAST FARTHER SW ALONG
SAME COLD FRONT AFFECTING THE MID ATLANTIC STATES/NORTHEAST.
PRESENCE OF MORE SUBSTANTIAL BOUNDARY LAYER MOISTURE SHOULD BOOST
SBCAPE TO AT LEAST 1000 J/KG...WITH HIGHER VALUES POSSIBLE IN
CNTRL/SRN AL...SE MS AND SRN LA. MODEST DEEP WNWLY SHEAR MAY
SUPPORT WEAK ORGANIZATION INTO BANDS/CLUSTERS WITH LOCALLY DAMAGING
WIND/HAIL.
..WI/NRN IL/IA/NRN MO/NEB...
COMPACT UPR VORT DROPPING SE ACROSS NRN MN SHOULD REACH SW WI THIS
EVENING...AND THE IND/OH BORDER AREA EARLY THURSDAY. IN ADDITION
..WV LOOP DEPICTS ANOTHER IMPULSE ACCELERATING SE ACROSS THE
DAKOTAS THAT SHOULD BE NEAR STL BY THE END OF THE PERIOD.
VERY COLD AIR ALOFT /-25 TO -29 C AT H5/ WITH MN VORT...COUPLED WITH
STRONG SFC HEATING...WILL RESULT IN SUBSTANTIAL DESTABILIZATION
ACROSS WI/NE IA AND NRN IL TODAY. EVEN WITH SFC DEWPOINTS AROUND 40
F...THIS WILL YIELD SBCAPE AOA 250 J/KG.
LOW LEVEL MASS FIELD RESPONSE TO UPPER VORT EXPECTED TO BE
LIMITED...BUT ASSOCIATED CONVERGENCE SHOULD BE SUFFICIENT TO SUPPORT
DENSE COVERAGE OF VIGOROUS/LOW-TOPPED CONVECTION/STORMS
BY AFTERNOON. THIS ACTIVITY WILL SPREAD SSE WITH TIME AND MAY
ORGANIZE INTO ONE OR TWO BANDS. COLD AIR ALOFT...LOW WBZ LEVELS AND
AMBIENT VERTICAL VORTICITY INVOF UPPER CENTER SUGGEST A THREAT FOR
MARGINALLY SVR HAIL AND PERHAPS FUNNELS/BRIEF TORNADOES UNTIL ABOUT
SUNSET.
FARTHER WSW...MORE WIDELY SCTD STORMS MAY FORM FROM CNTRL IA INTO
CNTRL NEB...IN ZONE OF ASCENT ASSOCIATED WITH DAKOTAS DISTURBANCE.
THESE PULSE CELLS MAY ALSO PRODUCE MARGINALLY SVR HAIL UNTIL SUNSET.
..SWRN U.S./FOUR CORNERS AREA...
ESELY LOW-LEVEL FLOW/OVERNIGHT STORM OUTFLOW WILL CONTINUE TO SPREAD
LOW-LEVEL MOISTURE W INTO PARTS OF NM AND AZ. COMBINATION OF
INCREASED MOISTURE...DAYTIME HEATING...OROGRAPHIC UPLIFT AND WEAK
ASCENT ASSOCIATED WITH IMPULSES UNDERCUTTING GRT BASIN RIDGE SHOULD
SUPPORT SCTD STRONG TO LOCALLY SVR AFTERNOON/EVENING STORMS. DEGREE
OF INSTABILITY AND DEPTH OF BOUNDARY LAYER SUGGEST A LOW-PROBABILITY
THREAT OF LOCALLY-DAMAGING WIND...HAIL AND HEAVY RAIN.
..SRN/CNTRL FL...
CONDITIONS APPEAR FAVORABLE FOR ONE MORE DAY WITH SCTD STRONG PULSE
STORMS OVER PARTS OF THE FL PENINSULA AS MID LEVEL TEMPERATURES
REMAIN A BIT COOLER THAN NORMAL. ACTIVITY MAY SPREAD A LITTLE
FARTHER N TODAY RELATIVE TO YESTERDAY AS WEAK SHEAR/FLOW WILL ALLOW
DEVELOPMENT TO PROPAGATE N THROUGH INTERIOR PARTS OF THE STATE.
.CORFIDI/CROSBIE.. 05/16/2007
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