MESO: Mesoscale Discussion 1683

ACUS11 KWNS 220050
SWOMCD
SPC MCD 220050
MEZ000-NHZ000-VTZ000-NYZ000-220215-

MESOSCALE DISCUSSION 1683
NWS STORM PREDICTION CENTER NORMAN OK
0750 PM CDT THU JUL 21 2011

AREAS AFFECTED...PORTIONS OF CNTRL MAINE...NRN NH...NRN VT...FAR
NERN NY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 220050Z - 220215Z

CLUSTERS OF STRONG TO POSSIBLY SVR STORMS WILL OCCUR THROUGH THIS
EVENING...AND THE ISSUANCE OF A WW IS POSSIBLE.

SFC MESOANALYSIS REVEALS AN E/W-ORIENTED CONFLUENCE AXIS DRAPED
ACROSS PORTIONS OF NEW ENGLAND AND SRN QUEBEC. THIS FEATURE IS
EXPECTED TO REMAIN THE FOCUS FOR MULTICELLULAR CONVECTIVE CLUSTERS
SHIFTING EWD/ESEWD THROUGH THIS EVENING. MODERATELY UNSTABLE INFLOW
-- I.E. 2375 J/KG OF MLCAPE PER GRAY MAINE 00Z OBSERVED SOUNDING --
WILL OFFER SUPPORT FOR VIGOROUS UPDRAFTS...WITH A THREAT FOR STRONG
TO POSSIBLY SVR STORMS ENSUING. EFFECTIVE BULK SHEAR MAGNITUDES OF
40 TO 50 KT WILL MAINTAIN SOME STORM ORGANIZATION/SUSTENANCE...WITH
THE THREAT FOR DMGG WIND GUSTS EMANATING FROM MORE ORGANIZED BOWING
STRUCTURES. THE ABSENCE OF MID-LEVEL FORCING FOR ASCENT /LITTLE
MID-LEVEL HEIGHT CHANGE NOTED OVER RECENT TIME/ AND WEAK MID-LEVEL
LAPSE RATES WILL LIKELY MITIGATE THE SVR THREAT TO SOME DEGREE.
HOWEVER...MODERATE TO STRONG FLOW ALOFT PER AREA VWP DATA AND THE
PRESENCE OF MID-LEVEL DRY AIR MAY ENHANCE THE THREAT FOR STRONG AND
POSSIBLY DMGG WIND GUSTS AT THE SFC. WHILE THE THREAT FOR A TORNADO
CANNOT BE RULED OUT SOUTH OF THE CONFLUENCE AXIS WHERE SUBTLE
LOW-LEVEL DIRECTIONAL SHEAR IS PRESENT...THIS THREAT WILL LIKELY BE
LIMITED WITH THE ANTICIPATION OF A PRIMARILY LINEAR CONVECTIVE MODE.

..COHEN.. 07/22/2011

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

ATTN...WFO...CAR...GYX...BTV...

LAT...LON 44356969 44377203 44337255 44587406 45067392 45027193
45387113 45677061 45776916 45476812 44936777 44616814
44506858 44356969

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