Storm Prediction Center Mesoscale Discussion 836


   Mesoscale Discussion 0836
   NWS Storm Prediction Center Norman OK
   0636 AM CDT Sat May 17 2025

   Areas affected...Upstate New York and northern Vermont

   Concerning...Severe potential...Watch unlikely 

   Valid 171136Z - 171400Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Thunderstorms will continue moving northeast this morning.
   Additional thunderstorms will develop later this morning and
   afternoon and a watch may eventually be needed.

   DISCUSSION...As a strong mid-level low slowly moves east across the
   Great Lakes today, multiple rounds of thunderstorms are anticipated
   across upstate New York, Vermont, and New Hampshire. These storms
   will be aided by increasing large-scale forcing from a number of
   sources: increasing upper-level divergence, lobes of positive
   vorticity advection, and the left exit region of a mid-level jet. 

   As diurnal heating increases this morning, cold mid-level
   temperatures will overspread the region. This, coupled with surface
   dewpoints ranging from the mid 50Fs to mid 60Fs will result in a
   largely unstable, uncapped environment, primed for thunderstorm
   development in association with one of the myriad of large-scale
   forcing mechanisms. 

   One such mechanism is already producing thunderstorms across far
   eastern portions of Lake Ontario. These thunderstorms should
   continue to rapidly move northeast into northern Vermont this
   morning. These thunderstorms will be capable of producing gusty
   winds and small hail. 

   The likelihood for a watch in the short-term is relatively low.
   However, as instability increases, and more widespread forcing for
   ascent moves into the area, a watch or watches may be needed across
   portions of the area by midday into early afternoon.

   ..Marsh/Bunting.. 05/17/2025

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

   ATTN...WFO...GYX...BTV...ALY...BGM...BUF...

   LAT...LON   43927225 43087390 42527564 42277680 42567763 43377876
               43787863 43687688 44287631 44637567 45097477 45097330
               45147184 44537152 43927225 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN

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