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Mesoscale Discussion 1493
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   MESOSCALE DISCUSSION 1493
   NWS STORM PREDICTION CENTER NORMAN OK
   0225 AM CDT MON JUL 20 2015

   AREAS AFFECTED...E-CNTRL NEW HAMPSHIRE....SWRN MAINE

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 200725Z - 200900Z

   PROBABILITY OF WATCH ISSUANCE...20 PERCENT

   SUMMARY...ISOLATED SEVERE HAIL MAY CONTINUE TO ACCOMPANY A SINGLE
   SUPERCELL AS IT TRACKS ESE TOWARDS THE PORTLAND AREA THROUGH 10Z.
   LIMITED SPATIOTEMPORAL EXTENT OF THE THREAT SHOULD PRECLUDE A SEVERE
   TSTM WATCH ISSUANCE.

   DISCUSSION...LONE SUPERCELL WHICH EARLIER PRODUCED QUARTER-SIZED
   HAIL AND TREE DOWN REPORTS IN VT HAD WEAKENED FOR A TIME BEFORE
   INTENSIFYING AGAIN OVER GRAFTON COUNTY NH...WITH QUARTER-SIZED HAIL
   REPORTED AS OF 0720Z. MRMS MESH DATA SUPPORT A PROBABLE SWATH OF
   SEVERE HAIL OCCURRING WITH THIS CELL. MLCAPE IS LIKELY MEAGER PER
   OBJECTIVE ANALYSIS IN THE WAKE OF ABUNDANT CONVECTIVE OVERTURNING ON
   SUN EVENING. BUT ADVECTION OF A STEEP MID-LEVEL LAPSE RATE PLUME
   SAMPLED IN 00Z BUF RAOB IN CONJUNCTION WITH ROBUST DEEP-LAYER SHEAR
   ASSOCIATED WITH THE SHORTWAVE IMPULSE ALONG THE ST LAWRENCE VALLEY
   IS CERTAINLY SUPPORTIVE OF HAIL GROWTH AND ELEVATED UPDRAFT
   ROTATION. THIS RISK ALONG WITH LOCALLY STRONG WINDS COULD PERSIST IN
   A NARROW CORRIDOR TO THE ATLANTIC COAST NEAR PORTLAND.

   ..GRAMS/EDWARDS.. 07/20/2015


   ATTN...WFO...GYX...

   LAT...LON   44007151 44017102 43887047 43777021 43627015 43437026
               43337047 43367076 43497119 43647153 43757173 43827175
               44007151 

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Page last modified: July 20, 2015
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