Storm Prediction Center Mesoscale Discussion 2253

   Mesoscale Discussion 2253
   NWS Storm Prediction Center Norman OK
   0207 PM CST Mon Dec 09 2024

   Areas affected...Portions of eastern New York into Vermont and New
   Hampshire

   Concerning...Winter mixed precipitation 

   Valid 092007Z - 100200Z

   SUMMARY...Wintry mixed precipitation is possible through the
   afternoon and evening hours across portions of eastern NY into
   portions of New England. Freezing rain and perhaps a bit of sleet
   appears likely over lower-terrain areas, with snow (perhaps up to 1
   inch/hr rates) over the higher terrain.

   DISCUSSION...A broad precipitation shield is approaching portions of
   New England from the southwest, driven by appreciable low-level
   warm-air and moisture advection. The approach of a pronounced
   mid-level trough, in tandem with low-level lee troughing, will
   encourage continued strong deep-layer accent, which will in turn
   favor the maintenance of the ongoing precipitation band.
   Furthermore, this band is approaching a tropospheric airmass that is
   largely sub-freezing just above the surface (per 20Z mesoanalysis).
   Wintry precipitation is underway, evident via bright-banding in MRMS
   mosaic radar imagery, ZDR/correlation coefficient transitions with
   KENX regional radar data, and the KGFL ASOS reporting moderate snow.

   RAP forecast soundings show near-saturated vertical profiles, with
   925-800 mb temperatures hovering around the freezing mark. However,
   current surface observations show wet bulb temperatures around or
   just below freezing. As such, evaporation with the onset of
   precipitation within the column should support enough cooling to
   potentially promote a rain/freezing rain/sleet mix over the lower
   elevations. In the higher elevations, wintry mix, dominated by snow,
   appears most likely. Given a saturated vertical profile, with strong
   700 mb frontogenesis (driven by a well-defined 700 mb impulse
   overspreading the northeast) a few instances of heavier snowfall are
   possible. Up to 1 inch/hr snowfall rates cannot be ruled out.

   ..Squitieri.. 12/09/2024

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

   ATTN...WFO...GYX...BTV...ALY...

   LAT...LON   43407141 43157180 42977267 43037318 43257385 43327397
               43747404 44327396 44607323 44567192 44237131 43837113
               43407141