SWODY1
SPC AC 181947
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CDT MON AUG 18 2008
VALID 182000Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NY AND NORTHERN
NEW ENGLAND...
...THERE IS A SLGT RISK OF SVR TSTMS OVER SRN FL PENINSULA...
...NY/NEW ENGLAND...
SCATTERED THUNDERSTORMS HAD DEVELOPED ACROSS WRN/NRN NY ALONG A WEAK
CONFLUENT BOUNDARY. THOUGH SHEAR IS NOT PARTICULARLY
IMPRESSIVE...STRONG HEATING AND MODERATE INSTABILITY IS FAVORABLE
FOR A FEW STORMS WITH SEVERE WINDS/HAIL...REFERENCE WW 838.
UPPER TROUGH OVER ONTARIO/QUEBEC CONTINUES TO SWEEP EWD TOWARD NEW
ENGLAND. THIS SYSTEM AND ACCOMPANYING COLD FRONT...WITH AN ONGOING
LINE OF STRONG/SEVERE THUNDERSTORMS...IS EXPECTED TO MOVE INTO
PORTIONS OF UPSTATE NY/WRN NEW ENGLAND BY 00Z. GIVEN STRENGTHENING
WIND FIELDS AND THE LINEAR NATURE OF THE CONVECTION ...WIND DAMAGE
SHOULD BE THE PRIMARY THREAT WITH THESE STORMS. THE SEVERE THREAT IS
EXPECTED TO DIMINISH BY 03Z TO 06Z DUE TO NOCTURNAL COOLING AND
RESULTANT STABILIZING BOUNDARY LAYER.
...FL...
THE CENTER OF TROPICAL STORM FAY AT MID AFTERNOON WAS LOCATED NEAR
KEY WEST...RESULTING IN WIND FIELDS TO STRENGTHEN ACROSS THE SRN FL
PENINSULA. SHEAR IN THE LOWEST 1 KM HAD INCREASED TO 15 TO 20 KT.
THIS SHEAR IN COMBINATION WITH SURFACE DEWPOINTS IN THE MID 70S
WOULD FAVOR A FEW TORNADOES...ESPECIALLY IN THE OUTER BANDS LOCATED
TO THE EAST AND NORTHEAST OF FAY/S CENTER.
...NM/TX...
CUTOFF UPPER LOW...CURRENTLY LOCATED OVER THE TX/OK PANHANDLES
...WAS DRIFTING SLOWLY SEWD. VERTICAL SHEAR WITH THIS SYSTEM IS
WEAKER THAN ON SUNDAY...BUT EFFECTIVE SHEAR AT 20-30 KT WAS PRESENT
ACROSS ERN NM/WRN TX. THE FORCING ASSOCIATED WITH THE UPPER LOW AND
THE WEAKLY CAPPED ENVIRONMENT SHOULD RESULT IN SCATTERED TO NUMEROUS
THUNDERSTORMS. WHERE BREAKS IN THE CLOUDS OCCUR...MODERATE
INSTABILITY IS LIKELY. THIS INSTABILITY ALONG WITH THE SHEAR MAY
SUPPORT A BRIEF HAIL/WIND THREAT IN A FEW STORMS UNTIL MID EVENING.
...WA/ORE...
UPPER PATTERN OVER THE PACIFIC NORTHWEST IS VERY SIMILAR TO
YESTERDAY...WITH A SHORTWAVE TROUGH LIFTING NWD FROM NRN CA.
CLOUDS/CONVECTION HAS RESTRICTED SOME HEATING...WHICH HAS LESSENED
THE THREAT FOR STRONG/SEVERE STORMS. HOWEVER...IF STORMS CAN DEVELOP
ON ERN EDGE OF PCPN/CLOUDS LOCATED OVER CENTRAL WA/ORE...VERTICAL
SHEAR AND STEEP MID LEVEL LAPSE RATES MIGHT SUPPORT A FEW STORMS
WITH GUSTY WINDS AND HAIL.
..IMY/KIS.. 08/18/2008
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