Mesoscale Discussion 52

Issued

Feb 1, 2021, 1:43 PM EST (18:43 UTC)

Expired

Feb 1, 2021, 7:45 PM EST

In force

6 hr

Issued by

the Storm Prediction Center

Concerning

Heavy snow

The Brookhaven radar (KOKX), 33 km from the middle of the area, began a volume at 18:46 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.

013 
ACUS11 KWNS 011843
SWOMCD
SPC MCD 011843 
MAZ000-RIZ000-NHZ000-CTZ000-NYZ000-NJZ000-PAZ000-DEZ000-MDZ000-020045-

Mesoscale Discussion 0052
NWS Storm Prediction Center Norman OK
1243 PM CST Mon Feb 01 2021

Areas affected...portions of far eastern Pennsylvania...central and
northern New Jersey...far southeast New York...Long
Island...Connecticut...Rhode Island...Massachusetts

Concerning...Heavy snow 

Valid 011843Z - 020045Z

SUMMARY...Up to 2-4 inch/hr snowfall rates will be possible across
portions of the lower Hudson Valley and southern New England this
afternoon, with occasional blizzard conditions possible across Long
Island. Portions of far eastern Pennsylvania into central New Jersey
will continue to experience a heavy sleet/snow mix.

DISCUSSION...A surface low continues to gradually deepen while
tracking slowly north-northeastward just off the Jersey shoreline as
a 110+ knot 300 mb jet traverses the Mid Atlantic/New England
Coastline. Strong 925-700 mb warm-air advection ahead/north of the
surface low continues to support ample mixed wintry
precipitation/heavy snowfall potential amidst a sub-freezing
tropospheric vertical profile and deep-layer ascent provided by
coupled low-level convergence with the surface low and upper-level
divergence by the strong 300 mb jet (per latest Mesoanalysis).
Latest KDIX/KOKX dual-polarimetric radar depicts a an east to west
snow/sleet transition zone roughly from KLOM to KISP. Latest METAR
observations also show 1-3 inch/hr snowfall rates ongoing just north
of this transition zone, and the heavier snow/sleet are expected to
gradually translate northward through the afternoon. METAR sites
also show 25 knot sustained northeasterly winds prevailing across
Long Island, along with heavy snow and higher gusts noted. As such,
brief and localized blizzard conditions are expected to persist.

Latest HREF, SREF, and last few runs of the HRRR suggest that
relatively lighter snowfall rates mixed with sleet will be the
predominant mode of precipitation from far eastern PA/central NJ
southward this afternoon, with a transition of sleet likely across
portions of Long Island and brief/localized blizzard conditions
still possible. Farther north across parts of southern New England,
the heavier band of wintry precipitation will progress northward,
with strong 700 mb warm-air advection and a near-saturated dendritic
growth zone supporting 1-3 inch/hr snowfall rates this afternoon, as
suggested by high-resolution model guidance. A few brief instances
of 4 inch/hr rates also cannot be ruled out.

..Squitieri.. 02/01/2021

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

ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM...CTP...LWX...

LAT...LON   39747651 40457586 41297484 42247351 42687247 42767149
            42507095 42067041 41917017 41727018 41367087 40977188
            40567253 40237347 39957418 39767492 39637561 39747651

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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.