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   FOUS11 KWBC 180904   
   QPFHSD   
      
   Probabilistic Heavy Snow and Icing Discussion   
   NWS Weather Prediction Center College Park MD   
   404 AM EST Sun Jan 18 2026   
      
   Valid 12Z Sun Jan 18 2026 - 12Z Wed Jan 21 2026   
      
      
   ...Great Lakes...   
   Days 1-3...   
      
   Shortwave trough passages around an anchored deep low over Hudson   
   Bay maintains cyclonic flow through the Great Lakes with rounds of   
   heavy lake effect snow through next weekend. The Great Lakes are=20   
   currently mostly ice free (total ice cover estimated at 14% on Jan=20   
   17), with surface water temperatures between 2-6C (warmer over=20   
   southern Lake Michigan and Lake Ontario).   
      
   A long wave trough shifts east of the Great Lakes this morning   
   while the next reinforcing trough swings east across the extent of   
   the Lakes this afternoon through Monday. NWly flow brings Day 1=20   
   PWPF for >6" around 50% to the western U.P. (particularly the=20   
   Porcupine Mtns) and the western shore of the L.P.=20   
      
   The flow shifts westerly for Monday shifting the LES focus to the=20   
   eastern U.P. northern L.P. and for the eastern Great Lakes for=20   
   Monday with westerly single banding bringing 50-80% probs for >6"=20   
   to ares south of Buffalo and on the Tug Hill through Watertown.=20   
      
   A brief lull in LES sweeps across the Lakes Tuesday, though   
   single-banding persists on the Eastern Great Lakes. In particular,   
   the Tug Hill should see notable Day 3 snow with 60% probs for >12".=20   
      
      
   ...Southeast, Mid-Atlantic, Northeast...   
   Day 1...   
      
   Positively-tilted full-latitude trough over the Mid-South=20   
   swing to neutral today as it shifts over the Southeast. Moisture   
   plume ahead of the trough is mainly rain, but with surface low   
   pressure developing off the GA coast, the back side of the precip   
   should turn into moderate bands of snow, particularly from the FL   
   Panhandle through central GA and the central Carolinas. With these   
   cases, even with surface temperatures just above freezing, dynamic   
   cooling could easily bring snow to the surface and accumulate via=20   
   decent rates of 0.5-0.75"/hr per the 00Z HREF. Day 1 PWPF for >2"   
   is around 10% in south-central GA and 20% in north-central NC into   
   southeast VA.   
      
   Further up the coast, precipitation will expand northeastward in=20   
   the right entrance of the >160kt jet atop marginal to cold=20   
   temperatures (milder along/east of I-95 in the Mid-Atlantic) and   
   increasing lower to mid-level FGEN. Elongated baroclinic zone and=20   
   the offshore surface low that rapidly develops as it passes Cape   
   Hatteras this afternoon and just outside the 40/70 benchmark=20   
   this evening. The westward extent of the precip shield, where the   
   snow bands will be is still prominent in 00Z guidance along the   
   extend of the Mid-Atlantic coast this afternoon and much of New   
   England late this afternoon through this evening. 00Z HREF mean snow   
   rates exceed 0.5"/hr over the Delmarva and NJ early this evening   
   and Long Island/southern New England late this evening through   
   midnight. Day 1 PWPF for >2" are 40% and up from Philly through   
   eastern Maine with 50% and up for >4" from NYC through CT/MA/RI and   
   along the immediate Maine coast. The max for the Day 1 PWPF is from   
   Providence to Boston where >6" probs are around 60%.=20   
      
      
   ...Northern Plains...   
   Day 1...   
      
   **Snow squalls and blizzard conditions likely across parts of the=20   
    northern Plains today. Key Messages linked below***   
      
   The next arctic cold front surges south across the northern Plains   
   today, with scattered snow squalls mainly this morning from eastern   
   Montana through the western Dakotas into central Nebraska. The   
   broad wind field with this front should also trigger blowing snow,   
   which when combined with additional falling snow could create   
   blizzard conditions, particularly in the WFO FGF CWA (please see   
   weather.gov/fgf for more info there).=20   
      
   Lapse rates reach or exceed 6-7C/km for a brief period along the=20   
   front and SNSQ parameters rise above 4-5 between eastern MT and=20   
   central NE. These parameters combined with low-to-mid level FGEN=20   
   intersecting with a healthy 100mb wide DGZ should allow for=20   
   efficient snowfall rates within these showers and bands. Wind gusts   
   up to 60 mph are also possible with this system, adding to the=20   
   blowing snow potential.   
      
   Snow squalls are particularly dangerous for those traveling on   
   roadways, with extremely low visibilities and slippery conditions   
   developing rapidly. Be sure to slow down, turn on your lights, and   
   exit the highway if possible should you get caught in a snow   
   squall.   
      
      
   ...Central High Plains...   
   Days 1-2...   
      
   Cold air surges over the High Plains/against the front ranges of=20   
   the Rockies today ahead of a reinforcing shortwave trough that   
   shifts south over the Rockies tonight through Monday. Right=20   
   entrance jet dynamics over the front will allow banded snow to=20   
   develop over central MT/WY this evening with stronger banding=20   
   overnight from northern CO terrain through western KS with snow   
   bands lingering Monday morning over southwest KS into western OK.=20   
   The WNWly orientation of these bands is parallel to the flow and=20   
   should allow for persistence of narrow bands of moderate to=20   
   locally heavy snow. Day 1 PWPF for >2" remain limited to 30% over=20   
   the CO Front Range and east of the Palmer Divide in CO/western KS.   
   CAMs generally struggled with these synoptically driven bands that   
   have a risk for high performance given the motion along   
   orientation, so there remains a threat for 4"+ in persistent=20   
   banding scenarios.   
      
   Jackson   
      
      
      
   ...Winter Storm Key Messages are in effect. Please see current=20   
    Key Messages below...   
      
   https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=   
   stKeyMessage_2.png__;!!DZ3fjg!8mgHyoidHlr2hQD8QC6_PkFw3gcML7nZY0LgmJfp3PNA_=   
   50yuIFMLCOpfSkQNcKumw5V4v5BVTNpxp0ITTZIl5fYnzo$=20   
      
      
      
   $$   
      
   =3D =3D =3D   
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