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   FOUS11 KWBC 220845   
   QPFHSD   
      
   Probabilistic Heavy Snow and Icing Discussion   
   NWS Weather Prediction Center College Park MD   
   345 AM EST Thu Jan 22 2026   
      
   Valid 12Z Thu Jan 22 2026 - 12Z Sun Jan 25 2026   
      
      
   ***Significant Winter Storm To Bring Potentially Crippling Impacts   
    To Parts Of The South Friday Through This Weekend, Expanding Up=20   
    The East Coast Saturday Night Into Sunday***   
      
   ...Southern Rockies and Southern Plains through the Ohio/Tennessee   
   Valleys into the Mid-Atlantic...   
   Days 2-3...   
      
   Estimated over 130 million residents under winter weather headlines   
   this morning as confidence continues to increase on a highly=20   
   impactful and extremely wide- reaching winter storm to begin on=20   
   Friday across the south-central U.S., eventually pushing towards=20   
   the East Coast by Saturday night into Sunday. Guidance has nearly=20   
   unanimously converged on the upper low churning just west of=20   
   southern CA (sampled by recon aircraft for the recent 00z model=20   
   suite) to eject eastward ahead of a diving northern stream=20   
   shortwave and fully phase by the day 4 timeframe. Uncertainty=20   
   remains associated with the speed of the approaching northern=20   
   stream trough, which eventually leads to the amplified pattern in=20   
   the central/eastern U.S.. However, this uncertainty has decreased=20   
   tonight as guidance converges on cluster 1 from WPC's 12z 1/21=20   
   clusters. Some guidance remains more amped (CMC/ECMWF) than others=20   
   (GFS) and leads to some lingering uncertainty regarding the=20   
   northern extent of heavy QPF and the mid- level warm nose. However,   
   all scenarios now point to a large QPF footprint falling in the=20   
   form of frozen precipitation and resulting in a significant winter   
   storm.   
      
   The aforementioned southern CA upper low will help surge ample=20   
   Pacific moisture (above the 90th climatological percentile per the=20   
   12z NAEFS) into the southern U.S. by Friday night, where a deep=20   
   arctic airmass is placed in ideal position for overrunning and=20   
   wintry precipitation. This arctic airmass in place is brought to=20   
   the region by a near record 1050mb surface high pressure over the=20   
   Northern Plains on Friday. As time progresses this high pressure is   
   expected to moderate and evolve into more of a "banana" look,=20   
   which is classic for heavy winter precipitation in the East as   
   low-levl cold air continues to sink southward towards a stationary   
   front forecast to stretch along the Gulf Coast. A few weak areas of   
   low pressure are forecast to form along this front before gradually   
   lifting northward into the TN Valley and along the Carolina=20   
   coastline by the end of D3. Decided to split up the remainder of=20   
   the discussion into hazard- type categories given this event covers   
   such a massive amount of real- estate. For local forecasts and=20   
   more details, read your local WFOs AFD.   
      
   Heavy Freezing Rain/Sleet...   
   Arguably the most lasting impact associated with this winter storm   
   could be from heavy accumulating freezing rain and sleet=20   
   stretching from the southern Plains, Mid-South, Tennessee Valley,=20   
   and southern Mid- Atlantic. This is due to very cold low-level=20   
   arctic air being reinforced by the strong high over the north-=20   
   central U.S. and a warm nose aloft (at around 750mb per cross=20   
   section model soundings) melting snow as it falls through the=20   
   column before refreezing just before or at the surface. The=20   
   greatest freezing rain amounts and impacts are currently forecast=20   
   across northeast TX through northern MS as favorable thermal=20   
   profiles linger for over 24 hours beginning Friday night. WPC=20   
   72-hour probabilities for >0.5" of freezing rain are high >70%=20   
   across southern AR into parts of northwest MS. Here, ice accretion=20   
   could be crippling and exceed 0.75-1.00", which would very likely=20   
   lead to widespread long- lasting damage to infrastructure,=20   
   including power outages and tree damage. Major sleet accumulations   
   are also likely just north of the freezing rain area stretching=20   
   from southern OK/north TX through central AR and into the Mid-   
   South, with more than a few inches of sleet possible. This could=20   
   make for treacherous driving conditions and lasting travel impacts=20   
   due to the bitterly cold airmass expected to linger into next week=20   
   over the region.   
      
   Heavy icing is also likely into the TN Valley and nearby southern=20   
   Appalachians and Mid- Atlantic, where freezing rain continues=20   
   beyond the D3 timeframe. The setup across the southern Mid-Atlantic   
   down as far south as northern GA and areas just inland from the=20   
   coasts of the Carolinas is an extreme case of CAD with a 1040mb=20   
   high situated over the Interior Northeast on Saturday night. This=20   
   high pressure filters very low/dry dew points with values below   
   zero prior to precip onset late Saturday. This cold air wedge   
   remains sharply locked in place at the surface for the remainder=20   
   of the event as 700-850mb temperatures begin to increase well above   
   freezing by the end of D3 throughout the Carolinas and northern=20   
   GA. WPC probabilities for >0.25" of freezing rain accretion through   
   12z Sun. are currently 40-70% from northern AL/TN through northern   
   GA and into the Midlands of SC and areas just inland of the NC=20   
   Tidewater region. Heavy sleet accumulations are also possible where   
   the low-level column remains colder into VA Piedmont.   
      
   Heavy Snow...   
   North of the mixed precipitation area and closely tide to both a=20   
   favorable LFQ of a zonally oriented 180kt upper jet and strong=20   
   700mb fgen, snow is the primary precipitation type stretching from=20   
   the southern High Plains of east-central NM and the southern=20   
   Rockies through the Plains, Mid-Mississippi Valley, Ohio Valley,=20   
   and Mid-Atlantic by Sunday morning. Favorable upslope flow as the=20   
   strong arctic high pressure noses southward along the High Plains=20   
   starts on Friday across the southern Rockies, with light snow and=20   
   even a chance for freezing drizzle at onset across the central=20   
   Plains until the column fully saturates. Heavy snow is then=20   
   forecast to begin breaking out Friday night from the=20   
   central/southern Plains through the mid-Mississippi Valley and=20   
   spanning much of the Ohio Valley and parts of the Midwest on=20   
   Saturday. Snowfall rates could near 1"/hr as strong lift intersects   
   with a region about 150 miles north of the mixed precip zone where=20   
   the DGZ is forecast to be extremely deep (about 500 mb per areal=20   
   average soundings). This would allow for efficient formation of=20   
   dendrites where ample lift can fully moisture the column. Should a=20   
   region remain in this zone for a longer enough period it's not out=20   
   of the realm of possibility 30:1 snow ratios are observed.=20   
   However, most locations appears to progressively see this favorable   
   DGZ move east-northeast with time and shrink as mid-level=20   
   temperatures increase above -8C and allows for more needles than=20   
   dendrites. WPC probabilities for >6" of snow through 12z Sun. are=20   
   medium to high (30-70%) stretching from east-central NM and the TX=20   
   Panhandle across northern OK, into the Mid-Mississippi Valley.=20   
   These probabilities increase to above 70% in the Ohio Valley,=20   
   where 8-10" of snow is possible. The widespread nature of this   
   heavy snow is likely to significantly impact both ground and air   
   travel in the region.   
      
   One area that is slowly becoming the most favorable location for=20   
   heavy snowfall rates and potentially the most impressive snowfall=20   
   amounts is the central Appalachians, northern VA, MD, and southern=20   
   PA through early Sunday. As the upper level trough deepens over the   
   central U.S. Saturday night, mid- level flow begins to increase=20   
   out ahead of it and meets the mid-level warm front stretching from   
   the eastern Ohio Valley into the Mid- Atlantic. Several 00z models   
   highlight increasing 700mb fgen over the eastern Ohio Valley and=20   
   into central VA by late D3, which supports the potential for an=20   
   extended period of 1"/hr rates across much of eastern WV,=20   
   central/northern VA, MD, and southern PA. The 0C warm nose may=20   
   begin to approach northern VA by the end of D3, but areas just to=20   
   the north could see 6-12" by sunrise on Sunday as precipitation=20   
   lingering further into the day on Sunday. Snow ratios will also be   
   favorable at onset and could potentially exceed 20:1 within   
   enhanced banding, which is well above the 11:1 climatology in the   
   region. Current WPC probabilities through D3 are medium to high=20   
   (40-70%) for at least 8" of snow, this includes areas just west of=20   
   I-95 from D.C. to Baltimore. Heavy snow is expected to continue=20   
   stretching into the Northeast and New England on Sunday, see WPC's=20   
   Extended Forecast Discussion for more. Also, see the Key Messages=20   
   linked at the bottom of this discussion.   
      
      
   ...Great Lakes...=20   
   Days 1-2...   
      
   A Hudson Bay vortex pivoting south through Ontario will sustain the   
   seemingly endless cyclonic flow over the Great Lakes and their   
   usual snow belts before strong high pressure builds overhead on D3   
   and ends this lake effect pattern for the time being. 500mb=20   
   heights associated with this powerful upper low are quite anomalous   
   (below the 1st climatological percentile per 12z NAEFS in southern   
   Ontario Thursday into Friday night). WPC probabilities highlight=20   
   medium-high chances (>60%) for snowfall totals >6" over the=20   
   northern tier of the U.P., along the Chautauqua Ridge on north=20   
   into western NY, and down wind of Lake Ontario over the Tug Hill.=20   
   The Tug Hill most notably will continue to receive very heavy snow=20   
   over the next few days highlighted by WPC 48-hour probabilities=20   
   sporting high chances (>70%) for >8" in the Tug Hill.=20   
      
   A growing concern is for snow squalls over the Northeast. WPC=20   
   initiated Key Messages for what appear to be multiple rounds of=20   
   snow squalls from western NY on east through New England, with some   
   squalls possible as far south as northern PA early today. This is   
   highlighted well in CAMs snow squall parameter, with highest   
   potential on Thursday from western PA through central NY. The=20   
   final round of squalls are expected on Friday as an arctic front=20   
   traverses the region, causing steep lapse rates and focused=20   
   vertical ascent. This front will also usher dangerously cold   
   temperatures and wind chills. For more details on the snow squall=20   
   threat in the Northeast through Friday, please refer to our Key=20   
   Messages.   
      
      
   Snell   
      
      
      
      
   ...Winter Storm/Snow Squall/Extreme Cold Key Messages are in=20   
   effect. Please see current Key Messages below...   
      
   https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=   
   stKeyMessage_1.png__;!!DZ3fjg!4SOx9iXiM3PgwTKiPMC2-PfsGt8BJz0BBMMz9h4kUUIjD=   
   IQTQvpLmpBzti1jhxxLn8WLhLWkb5WyZSxjoet_GDZdtno$=20   
      
   https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=   
   stKeyMessage_2.png__;!!DZ3fjg!4SOx9iXiM3PgwTKiPMC2-PfsGt8BJz0BBMMz9h4kUUIjD=   
   IQTQvpLmpBzti1jhxxLn8WLhLWkb5WyZSxjoet_AHZ3rCs$=20   
      
   https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=   
   stKeyMessage_3.png__;!!DZ3fjg!4SOx9iXiM3PgwTKiPMC2-PfsGt8BJz0BBMMz9h4kUUIjD=   
   IQTQvpLmpBzti1jhxxLn8WLhLWkb5WyZSxjoet_3CqF82U$=20   
      
      
      
   $$   
      
   =3D =3D =3D   
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