SPC AC 150600
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0100 AM CDT TUE MAY 15 2007
VALID 151200Z - 161200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF NEW ENGLAND AND
THE LOWER GREAT LAKES SWWD INTO THE OZARKS...
...SYNOPSIS...
UPPER TROUGH OVER THE N CENTRAL CONUS AT THE START OF THE PERIOD
SHOULD DIG/STRENGTHEN WITH TIME AS IT MOVES ACROSS THE MS
VALLEY/UPPER GREAT LAKES AND EVENTUALLY INTO THE OH VALLEY.
ELSEWHERE...A RIDGE WILL PREVAIL ACROSS THE ROCKIES...WHILE A
WEAKER/FLAT RIDGE MOVES EWD ACROSS THE ERN CONUS INTO THE WRN
ATLANTIC AHEAD OF THE DIGGING CENTRAL U.S. TROUGH.
AT THE SURFACE...MAIN FEATURE WILL BE A COLD FRONT WHICH WILL MOVE
SLOWLY EWD AHEAD OF UPPER TROUGH. BY LATE AFTERNOON...THIS BOUNDARY
AND ITS ASSOCIATED LINE OF THUNDERSTORMS SHOULD EXTEND FROM NEW
ENGLAND/NY WSWWD ACROSS THE LOWER GREAT LAKES/MIDWEST AND INTO THE
SRN PLAINS.
...THE OZARKS NEWD INTO THE LOWER GREAT LAKES/NEW ENGLAND...
STORMS SHOULD BE ONGOING INVOF FRONT DURING THE START OF THE
PERIOD...THOUGH CONVECTION SHOULD REMAIN GENERALLY SUB-SEVERE
THROUGH EARLY AFTERNOON.
MODERATE DESTABILIZATION WILL OCCUR THROUGH THE AFTERNOON...AS
COMBINATION OF DAYTIME HEATING AND DEWPOINTS IN THE 60S AHEAD OF THE
FRONT SHOULD RESULT IN 1000 TO 2000 J/KG MEAN-LAYER CAPE.
AS STORMS REDEVELOP ALONG/AHEAD OF FRONT...LINEAR STORM MODE SHOULD
QUICKLY EVOLVE. MODERATE DEEP-LAYER WIND FIELD -- PARTICULARLY FROM
THE LOWER OH VALLEY ENEWD -- WILL SUPPORT SMALL-SCALE BOWS WITHIN
THE LINE. THEREFORE...LOCALLY-DAMAGING WINDS WILL BE POSSIBLE IN
ADDITION TO THE THREAT FOR HAIL. GREATEST SEVERE THREAT APPEARS TO
EXIST ACROSS PARTS OF IL/IN/OH...WHERE 40 KT FLOW AT LOW- TO
MID-LEVELS IS EXPECTED.
OTHER STORMS MAY DEVELOP DURING THE AFTERNOON IN A W-E ZONE FROM NEW
YORK EWD ACROSS PARTS OF VT/NH/MA...AHEAD OF WEAK SURFACE LOW.
COMBINATION OF MEAN-LAYER CAPE NEAR 500 J/KG AND 50 TO 60 KT
DEEP-LAYER FLOW SUGGESTS DAMAGING WIND POTENTIAL ACROSS THIS
CORRIDOR.
THOUGH CONVECTION SHOULD PERSIST FROM PARTS OF NEW ENGLAND/NY SWWD
ACROSS THE OH/MID MS VALLEY REGION INTO THE OVERNIGHT HOURS...SEVERE
THREAT SHOULD SLOWLY WANE AS BOUNDARY LAYER STABILIZES WITH TIME.
...SRN NM/FAR W TX...
MARGINAL BOUNDARY-LAYER MOISTURE IS FORECAST N OF THE SURFACE COLD
FRONT...WHICH SHOULD MOVE SWD ACROSS THIS REGION THROUGH THE
AFTERNOON. THIS RELATIVE LACK OF MOISTURE AND LAPSE RATES WHICH
SHOULD NOT BE PARTICULARLY STEEP SHOULD RESULT IN ONLY MARGINAL
AFTERNOON DESTABILIZATION.
FAVORABLE POST-FRONTAL ELY/NELY LOW-LEVEL UPSLOPE FLOW SHOULD BE
SUFFICIENT FOR SCATTERED STORM DEVELOPMENT DURING THE AFTERNOON.
WHILE WLY MID-LEVEL FLOW SHOULD REMAIN WEAK /AROUND 15
KT/...LOW-LEVEL ELYS BENEATH THE WLYS ALOFT MAY RESULT IN SUFFICIENT
SHEAR FOR A FEW STRONGER/MULTICELL STORMS. ALONG WITH THE POTENTIAL
FOR A FEW HAIL REPORTS...EVAPORATIVELY-COOLED DOWNDRAFTS MAY ALSO
YIELD A FEW STRONGER WIND GUSTS.
...S FL...
MOIST BOUNDARY LAYER IS FORECAST ACROSS S FL...WHICH SHOULD
CONTRIBUTE TO 500 TO 1000 J/KG MEAN-LAYER CAPE DURING THE AFTERNOON.
WHILE DEEP-LAYER SHEAR WILL REMAIN WEAK...ELY LOWER-TROPOSPHERIC
FLOW ACROSS S FL SUGGESTS AN ACTIVE W COAST SEA BREEZE. WITH A FEW
PULSE-TYPE SEVERE STORMS POSSIBLE...WILL MAINTAIN 5% SEVERE
PROBABILITY ACROSS SRN PORTIONS OF THE FL PENINSULA FOR AFTERNOON
CONVECTION.
..GOSS/CROSBIE.. 05/15/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
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