Mesoscale Discussion 1399
   NWS Storm Prediction Center Norman OK
   0444 PM CDT Tue Aug 04 2020

   Areas affected...New England

   Concerning...Tornado Watch 417...

   Valid 042144Z - 042345Z

   The severe weather threat for Tornado Watch 417 continues.

   SUMMARY...An isolated tornado threat may develop across parts of New
   England to the north of Tornado Watch 417 over the next few hours.
   The threat is expected to be too marginal for weather watch
   issuance.

   DISCUSSION...Tropical Storm Isaias is currently located in southeast
   New York. A distinct band of heavy rainfall is ongoing in the
   northeast quadrant of Isaias from southern Vermont extending
   southeastward into eastern Massachusetts. This band consists of
   several discrete cells that are moving quickly northward across the
   northern part of WW 417. This convection will move into southern
   Maine and across Vermont and New Hampshire. The WSR-88D VWP at Gray,
   Maine shows easterly surface winds with gradually veering winds to
   the south-southeast at 3 km above ground. This combined with speed
   shear in the low-levels is creating 0-3 km storm relative helicities
   near 500 m2/s2. However, further to the north, the airmass is less
   unstable and surface dewpoints are only in the 60s F. Therefore, any
   tornado threat with the stronger rotating cells within the line
   should remain marginal.

   ..Broyles/Hart.. 08/04/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...CAR...GYX...BOX...

   LAT...LON   42137074 42947022 43506969 43856914 44066861 44376849
               44666869 44866899 44986937 44797003 44097116 43637176
               43277208 42787209 42287134 42137074