MESO: Mesoscale Discussion 1001

ACUS11 KWNS 091549
SWOMCD
SPC MCD 091548
NYZ000-PAZ000-091715-

MESOSCALE DISCUSSION 1001
NWS STORM PREDICTION CENTER NORMAN OK
1048 AM CDT TUE JUN 09 2009

AREAS AFFECTED...PORTIONS OF CNTRL NY SWWD INTO WRN PA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 091548Z - 091715Z

TSTMS ARE EXPECTED TO DEVELOP THIS AFTERNOON ALONG SEWD-MOVING COLD
FRONT. THE MORE INTENSE STORMS WILL BE CAPABLE OF DAMAGING WINDS
AND SOME HAIL. REGION WILL BE UPGRADED TO SLIGHT RISK AT 1630Z AND
CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.

15Z MESOANALYSIS INDICATED A COLD FRONT EXTENDING FROM LOW PRESSURE
N OF ART SWWD THROUGH WRN NY /E OF JHW/...NWRN PA INTO CNTRL OH. A
WARM FRONT THEN STRETCHED GENERALLY SSEWD FROM THE SURFACE LOW TO W
OF UCA...E OF AVP INTO THE DELMARVA. CONSIDERABLE DIABATIC HEATING
WITHIN WARM SECTOR AIR MASS IS RESULTING IN THE DEVELOPMENT OF STEEP
LOW LEVEL LAPSE RATES WITH MLCAPE INCREASING TO 1000-2000 J/KG BASED
ON MODIFICATION OF 12Z REGIONAL SOUNDINGS AND LATEST OBJECTIVE
GUIDANCE.

MORNING WATER VAPOR IMAGERY SUGGESTS THAT A NUMBER OF WEAK MIDLEVEL
IMPULSES AREA EMBEDDED WITHIN QUASI-ZONAL FLOW REGIME...THE MOST
NOTABLE OF WHICH IS FEATURE OVER IND INTO WRN OH AS OF 1540Z.
FORCING FOR ASCENT ASSOCIATED WITH THIS IMPULSE COUPLED WITH
LOW-LEVEL CONVERGENCE ALONG FRONT SHOULD BE SUFFICIENT TO FOSTER
SCATTERED TSTM DEVELOPMENT ALONG AND AHEAD OF BOUNDARY BY EARLY
AFTERNOON. STRONGEST DEEP-LAYER FLOW FIELDS /REF. 12Z BUF SOUNDING/
WILL LIKELY REMAIN N OF THE NY/PA BORDER WITH A GENERAL DECREASE IN
ZONAL MOMENTUM WITH SWD EXTENT. NONETHELESS...THE PRESENCE OF THE
STEEPENING LAPSE RATES AND MODERATE CONVECTIVE INSTABILITY MAY
PROMOTE CLUSTERS AND/OR BANDS OF STRONG TO SEVERE STORMS CAPABLE OF
LOCALLY DAMAGING WINDS AND PERHAPS SOME HAIL.

..MEAD.. 06/09/2009

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

ATTN...WFO...ALY...BGM...BUF...CTP...PBZ...

LAT...LON 40978037 41677906 42847749 43247654 43337581 43187534
42487501 41167652 39847908 40328040 40978037

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