Mesoscale Discussion 1950

Issued

Nov 26, 2021, 4:42 PM EST (21:42 UTC)

Expired

Nov 26, 2021, 7:45 PM EST

In force

3 hr

Issued by

the Storm Prediction Center

Concerning

Heavy snow

Counties Berkshire County, MA, Columbia County, NY, Rensselaer County, NY, Saratoga County, NY, Washington County, NY, Addison County, VT, Bennington County, VT, Caledonia County, VT, Chittenden County, VT, Essex County, VT, Lamoille County, VT, Orange County, VT, Orleans County, VT, Rutland County, VT, Washington County, VT, Windham County, VT, Windsor County, VT

The Burlington radar (KCXX), 80 km from the middle of the area, began a volume at 21:44 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

058 
ACUS11 KWNS 262143
SWOMCD
SPC MCD 262142 
NHZ000-VTZ000-MAZ000-CTZ000-NYZ000-270045-

Mesoscale Discussion 1950
NWS Storm Prediction Center Norman OK
0342 PM CST Fri Nov 26 2021

Areas affected...portions of western New England

Concerning...Heavy snow 

Valid 262142Z - 270045Z

SUMMARY...An uptick in heavy snow is possible over the next several
hours across portions of New England as temperatures cool and local
topography enhances precipitation development. Snow rates may
occasionally surpass 1 inch per hour resulting in low visibility and
fast accumulation.

DISCUSSION...As of 2140 UTC, regional water vapor imagery showed a
negatively-tilted upper low across southern Canada and upstate NY.
across much of New England ahead of the upper low, synoptic ascent
was supporting widespread precipitation in the form of rain and
snow. While initially above freezing, surface temperatures ahead of
the upper low have begun to drop in response to dynamic cooling from
precipitation increasing in coverage and intensity, as well as
increasing low-level cold advection from west/northwesterly
low-level flow. NEXRAD and local observations from KNEX show a band
of heavier snowfall, with rates of 1 to 2 inches per hour, has
developed near the NY, MA and VT borders. Likely enhanced by local
topography and weak 850-700 mb frontogenesis, this snow band may
produce occasional heavy snow with rates of 1-2 inches per hour as
it slowly moves north and east through this evening. 

A change over to snow and the potential for periodic heavy snow will
also develop farther north across portions of western VT and NH as
surface temperatures continue to cool this evening. Model soundings
show surface temperatures falling below freezing by 22-23z with
steadily increasing DGZ depths. The favorable large-scale ascent and
sufficiently moist/cool airmass should support the potential for 1
inch per hour snow rates for a few hours before forcing weakens and
shifts to the east later this evening.

..Lyons.. 11/26/2021

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

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

LAT...LON   45087176 45137163 44747148 44567152 43987184 41857324
            41937358 42037380 42387391 43307387 44447344 44897284
            45047256 45087176

Mesoscale Discussions in Vermont, 2021Mesoscale Discussions in New York, 2021Mesoscale Discussions in Massachusetts, 2021Every mesoscale discussion in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.