RSS Mesoscale Discussions from Storm Prediction Center
No watches are valid as of Fri Dec 26 19:51:02 UTC 2025.
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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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
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SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1026 AM CST Fri Dec 26 2025
Valid 261630Z - 271200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not forecast across the contiguous United
States through tonight.
...Synopsis and Discussion...
An upper trough will continue to progress eastward over the western
CONUS today. With cool temperatures at mid levels supporting weak
MUCAPE, isolated thunderstorms may occur across parts of CA into the
Great Basin and northern Rockies through the period as large-scale
ascent associated with the upper trough spreads inland. Mid-level
flow and related deep-layer shear should remain strong enough to
support some updraft organization across these areas, but limited
low-level moisture, cool surface temperatures, and overall weak
instability will likely hinder a meaningful severe threat from
materializing today. Elsewhere, isolated lightning flashes may occur
with elevated convection in a strong low-level warm advection regime
over portions of the Great Lakes into the Mid-Atlantic and southern
NY as a mid-level shortwave trough advances east-southeastward
across these areas.
..Gleason/Wendt.. 12/26/2025
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SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0146 PM CST Fri Dec 26 2025
Valid 262000Z - 271200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms are not forecast across the contiguous United
States through tonight.
...20Z Update...
The general thunderstorm forecast was updated in the Lower Great
Lakes region on account of the shortwave trough progression. The
remainder of the forecast remains valid and is unchanged. See the
previous discussion for additional information.
..Wendt.. 12/26/2025
.PREV DISCUSSION... /ISSUED 1026 AM CST Fri Dec 26 2025/
...Synopsis and Discussion...
An upper trough will continue to progress eastward over the western
CONUS today. With cool temperatures at mid levels supporting weak
MUCAPE, isolated thunderstorms may occur across parts of CA into the
Great Basin and northern Rockies through the period as large-scale
ascent associated with the upper trough spreads inland. Mid-level
flow and related deep-layer shear should remain strong enough to
support some updraft organization across these areas, but limited
low-level moisture, cool surface temperatures, and overall weak
instability will likely hinder a meaningful severe threat from
materializing today. Elsewhere, isolated lightning flashes may occur
with elevated convection in a strong low-level warm advection regime
over portions of the Great Lakes into the Mid-Atlantic and southern
NY as a mid-level shortwave trough advances east-southeastward
across these areas.
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SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1123 AM CST Fri Dec 26 2025
Valid 271200Z - 281200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe storms are not expected on Saturday or Saturday night.
...Synopsis...
Mid-level ridging over the central US is forecast to weaken as
broader troughing over the West begins to move eastward. A
positive-tilt lead shortwave will move from the central Rockies over
the Plains, into the upper OH Valley Saturday and Saturday night.
Lift from this feature will deepen a surface low over the MO Valley
allowing for some return moisture and an increase in low-level warm
advection Saturday night. Weak elevated buoyancy may develop and
support isolated thunderstorms ahead of the trough from eastern
KS/OK into the upper OH Valley. Severe potential appears limited
owing to MUCAPE generally below 500 J/kg and the potential for any
stronger storms to mainly exist beyond 12z Sunday (Day 3).
..Lyons.. 12/26/2025
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SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0130 PM CST Fri Dec 26 2025
Valid 281200Z - 291200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE MID MISSISSIPPI AND OHIO VALLEYS...
...SUMMARY...
Isolated severe thunderstorms are possible Sunday into Sunday night
from the Southern Great Lakes into parts of the Ohio and Mid
Mississippi Valleys.
...Mid MS to the OH Valleys...
An initially broad and multi-faceted positive-tilt upper trough over
the central US is forecast to undergo substantial amplification as
it moves eastward toward the Great Lakes Sunday and Sunday night.
The corresponding surface low will quickly intensify as it moves
eastward from KS/MO across northern IL. A trailing cold front will
also strengthen, with low-level moisture transport ahead of the
front (50s and 60s F surface dewpoints) aiding in modest
destabilization Sunday evening.
Elevated convection is likely to be ongoing over the MO valley
vicinity early in the period associated with the strong low-level
theta-E advection. This convection may remain elevated for much of
the day as it tracks along a stalled frontal zone from northern
MO/IL vicinity eastward into OH/IN and southern lower MI. Still,
some elements may eventually become near-surface based with weak
MUCAPE (100-200 J/kg) potentially supporting a few stronger gusts
near the surface.
Additional surface-based storms will likely develop within the
moistening warm sector over the northern Ozarks and mid MS valley
late Sunday afternoon. A low-topped convective band could organize
along the front as it moves east/southeast from the MS/OH Valleys
toward the northern Gulf Coast. As the trough and surface low
deepen, flow aloft will also increase. A strong (45-55+ kt)
low-level jet will develop from the Mid South to the southern Great
Lakes, rapidly strengthening low and mid-level shear profiles. While
buoyancy will be marginal (250-500 J/kg MUCAPE), this should be
sufficient for stronger linear segments to organize along the
surging cold front. Isolated damaging gusts and perhaps a brief
tornado or two are possible as the line moves quickly eastward over
the Mid MS and eventually the OH Valley Sunday night.
..Lyons.. 12/26/2025
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SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
1054 AM CST Fri Dec 26 2025
Valid 261700Z - 271200Z
Minor adjustments to the outlook were made based on a southwestward
trend in the morning guidance with respect to the corridor of
strongest westerly winds across portions of the Texas Panhandle and
northeastern New Mexico this afternoon. Otherwise, the forecast
remains on track.
..Supinie.. 12/26/2025
.PREV DISCUSSION... /ISSUED 1227 AM CST Fri Dec 26 2025/
...Synopsis...
An upper-level ridge over the central CONUS will remain
quasi-stationary throughout the day, with an embedded speed max
traversing the ridge from the Southwest into the Central Plains.
Diurnal heating/mixing will allow this enhanced flow aloft to mix
toward the surface, resulting in sustained westerly winds near 15
mph across portions of the southern High Plains. Additionally,
downslope westerly winds near 15-20 mph should develop along the lee
of the Rockies, extending into portions of central Colorado during
the afternoon. Afternoon RH values across these regions should fall
into the lower teens amid dry/receptive fuels, promoting Elevated
fire-weather conditions.
...Please see www.spc.noaa.gov/fire for graphic product...
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SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook
NWS Storm Prediction Center Norman OK
0126 PM CST Fri Dec 26 2025
Valid 271200Z - 281200Z
Some dry, downslope westerly winds are possible across portions of
northeastern Colorado during the day on Saturday ahead of a surface
cold front. Given the receptive fuels in the area, this may lead to
some brief Elevated fire weather risk during the afternoon. However,
uncertainty on the degree to which mid- and upper-level cloud cover
will impact mixing, and therefore the RH and wind strength, preclude
adding any highlights at this time. Otherwise, the previous forecast
remains largely on track with only minor adjustments made to the
Elevated highlights over the Texas Panhandle.
..Supinie.. 12/26/2025
.PREV DISCUSSION... /ISSUED 1228 AM CST Fri Dec 26 2025/
...Synopsis...
An upper-level ridge will remain in place along with an embedded
speed max across the central/southern Plains. The combination of lee
troughing and mixing should allow for sustained winds of 15-20 mph
to develop during the afternoon across the OK/TX Panhandles and
vicinity. Despite somewhat marginal RH values, perhaps approaching
the low to mid 20s, persistent dry conditions have led to
dry/receptive fuels, which will promote a few hours of Elevated
fire-weather conditions for this region.
...Please see www.spc.noaa.gov/fire for graphic product...
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