Mesoscale Discussion

SPC MD 2275

MD 2275 CONCERNING HEAVY SNOW FOR WESTERN NEW YORK INTO NORTHEAST PENNSYLVANIA
        

Mesoscale Discussion 2275
NWS Storm Prediction Center Norman OK
1222 PM CST Fri Dec 26 2025

Areas affected...Western New York into northeast Pennsylvania

Concerning...Heavy snow 

Valid 261822Z - 262215Z

SUMMARY...A favorable zone for heavy snow banding is becoming
established across parts of western New York into northeast
Pennsylvania. Snowfall rates between 1-2 in/hour will be possible
under any band that develops within this region through late
afternoon.

DISCUSSION...Precipitation banding has begun to emerge across
portions of NY/PA  over the past couple of hours amid strengthening
warm air advection between 850-700 mb and increasing, albeit modest,
broad-scale ascent ahead of a low-amplitude upper wave. Dry air in
the lowest few kilometers has limited precipitation amounts at the
surface for most locations thus far; however, automated observations
and web cams between Buffalo and Rochester, NY have begun to report
moderate to heavy snowfall with visibility reductions between 1/2 to
1/4 mile at times under one of the consolidating bands.
Concurrently, NY Mesonet observations are depicting steady surface
moistening with dewpoints climbing by 1-2 F/hour as low-level
profiles saturate under the heavier precipitation bands. 

While the heaviest snowfall will likely occur later this evening as
the upper wave moves over the region, these observed trends suggest
that the onset of moderate/heavy snowfall rates is likely beginning.
Areas that can maintain residence time under an established snow
band may observe snowfall rates as high as 1-2 in/hour as soon as
low-level saturation occurs. Favorable overlap of synoptic and
mesoscale ascent will continue to promote snow band development
within the warm advection branch of the disturbance, which will
maintain heavy snowfall potential at least through late afternoon
and possibly into the late evening hours.

..Moore.. 12/26/2025

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

ATTN...WFO...OKX...ALY...PHI...BGM...BUF...CTP...

LAT...LON   41207542 42427792 42737817 42997819 43217807 43367793
            43467752 43467703 43377656 42097437 41687429 41427455
            41177512 41207542 


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SPC MD 2274

MD 2274 CONCERNING FREEZING RAIN FOR NORTHERN MARYLAND...CENTRAL TO NORTHWEST PENNSYLVANIA...AND FAR WESTERN NEW YORK

Mesoscale Discussion 2274
NWS Storm Prediction Center Norman OK
1013 AM CST Fri Dec 26 2025

Areas affected...Northern Maryland...central to northwest
Pennsylvania...and far western New York

Concerning...Freezing rain 

Valid 261613Z - 262115Z

SUMMARY...A wintry mix, eventually transitioning to primarily light
to moderate freezing rain, will spread southeast through the
afternoon into northwest and central Pennsylvania and western New
York.

DISCUSSION...Recent mPING reports and ASOS/AWOS observations are
beginning to show areas of light freezing rain and sleet spreading
from far northeast OH into northwestern PA and far western NY over
the past 1-2 hours. Although regional 12z soundings sampled a stout
dry layer from the surface to about 3 km, the recent sleet/freezing
rain reports indicate that preceding precipitation has allowed for
adequate saturation in the mid/low-levels to allow hydrometeors to
reach the surface. Consequently, surface sleet/freezing rain amounts
will likely increase through the afternoon as more widespread
precipitation (attendant to a mid-level wave currently upstream
across southeast MI) overspreads the region. 

Correlation Coefficient imagery from KPBZ and KCCX are sampling a
melting layer between 4-8 kft ARL over central PA, which should be
maintained through the afternoon amid increasing warm advection
between 925-850 mb. Near the surface, weak thermal advection below
0.5 km should maintain sub-freezing temperatures and support
freezing hydrometeors. Although a mix of sleet/freezing rain is
expected over the next couple of hours, a transition to primarily
freezing rain is anticipated this afternoon as the depth/strength of
the warm nose aloft increases. Latest forecast guidance supports
this scenario and suggests that freezing rain rates upwards of 0.05
to 0.1 inch/hour will be possible across central PA into far western
NY - especially under heavier precipitation bands and/or where
precipitation rates are locally enhanced by weak convective
processes.

..Moore.. 12/26/2025

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

ATTN...WFO...BUF...CTP...LWX...PBZ...CLE...

LAT...LON   42397956 42537915 42517885 40907699 40487663 40117667
            39707684 39537725 39457795 39547855 39687892 39977920
            40187931 40427948 40537956 41428044 41768079 41958070
            42148015 42397956