Saturday, August 16, 2008

MESO: Mesoscale Discussion 2103

ACUS11 KWNS 161657
SWOMCD
SPC MCD 161656
MEZ000-MAZ000-NHZ000-VTZ000-CTZ000-NYZ000-161900-

MESOSCALE DISCUSSION 2103
NWS STORM PREDICTION CENTER NORMAN OK
1156 AM CDT SAT AUG 16 2008

AREAS AFFECTED...EXTREME ERN NY...WRN/CENTRAL
MA...VT...CENTRAL/DOWNEAST ME

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 161656Z - 161900Z

CONVECTION IS INCREASING FROM EXTREME ERN NY INTO PARTS OF NRN NEW
ENGLAND BENEATH COLD UPPER TROUGH MOVING SLOWLY ACROSS THE AREA.
STRONGER CELLS WILL BE CAPABLE OF PRODUCING MARGINALLY SEVERE HAIL
AND OCCASIONAL GUSTY SURFACE WINDS. LACK OF A LOW LEVEL FOCUSING
MECHANISM AND EXPECTATION THAT EXISTING CAPE WILL BE QUICKLY
UTILIZED AS CAP WEAKENS OVER THE AREA SUGGESTS THAT A WATCH MAY NOT
BE NEEDED...BUT TRENDS WILL CONTINUE TO BE MONITORED.

THUNDERSTORMS HAVE BEEN DEVELOPING WITHIN THE UPPER TROUGH AXIS FROM
WRN ME SSWWD INTO ERN NY...WHERE LATEST RUC GUIDANCE INDICATES 500
MB TEMPERATURES OF -16 TO -19C. CONVECTIVE CELLS HAVE DEVELOPED
RAPIDLY DURING THE LATE MORNING/EARLY AFTERNOON AS DIABATIC HEATING
WITHIN CLOUD-FREE REGIONS HAS WEAKENED THE CAP. RESIDUAL MOISTURE
WITH SURFACE DEWPOINTS IN THE UPPER 50S COUPLED WITH TEMPERATURES
WARMING INTO THE LOW-MID 70S ARE CONTRIBUTING TO UNSTABLE
CONDITIONS WITH MLCAPE OF 1000-1300 J/KG ACROSS THE REGION. MID
LEVEL WINDS ALOFT IN PROXIMITY TO THE TROUGH AXIS ARE 20-30 KT WHICH
IS LIMITING THE DEEP LAYER SHEAR AND ASSOCIATED SHEAR-RELATED
ENHANCEMENT OF STORM ORGANIZATION AND INTENSITY.
HOWEVER...MODERATELY STEEP LAPSE RATES AIDING UPWARD PARCEL
ACCELERATIONS ABOVE THE LFC AND LOW WBZ LEVELS OF 7-9 KFT WILL
INCREASE THE HAIL THREAT WITH STRONGER CELLS.

..WEISS.. 08/16/2008

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...CAR...GYX...BOX...BTV...ALY...

43857379 44327342 44787196 45437083 46007033 46246959
46066876 45276834 44276914 43287036 42547118 41987192
41887272 41987365 43067387

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