TZUTC: 0000   
   MSGID: 167365.weather@1:2320/105 2d9ba319   
   PID: Synchronet 3.21a-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0   
   TID: SBBSecho 3.28-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0   
   BBSID: CAPCITY2   
   CHRS: ASCII 1   
   FORMAT: flowed   
   FOUS11 KWBC 060746   
   QPFHSD   
      
   Probabilistic Heavy Snow and Icing Discussion   
   NWS Weather Prediction Center College Park MD   
   246 AM EST Sat Dec 6 2025   
      
   Valid 12Z Sat Dec 06 2025 - 12Z Tue Dec 09 2025   
      
   ...Central Rockies..   
   Day 1...   
      
   500mb height falls, the divergent left-exit region of a strong   
   250mb jet streak, and a plume of anomalous PWATs (above the 90th   
   climatological percentile per ECMWF) are all working together to   
   produce heavy mountain snow from the Wasatch, Uinta, and Wind River   
   ranges to the Rockies of southern WY and much of CO. Upslope   
   enhancement will be focused along the Wasatch and CO/WY Rockies   
   through this morning. As the core of the best moisture content   
   exits east this afternoon, snow will gradually taper off Saturday   
   night. WPC probabilities sport high chances (>70%) for additional   
   snowfall totals >12" in the Wasatch above 8,000ft and CO/WY   
   Rockies above 9,000ft. WPC's WSSI highlights Moderate Impacts at   
   these listed elevations with some localized Major Impacts in the   
   more remote peaks of the UT, WY, and CO Rockies.   
      
      
   ...Pacific Northwest & Northern Rockies...   
   Days 1-3...   
      
   The Pacific Northwest and Northern Rockies will continue to contend   
   with the lingering effects of the ongoing atmospheric river (AR)   
   through the remainder of the day Saturday. WPC probabilities show   
   high chances (>70%) for additional snowfall totals >8" in the more   
   remote reaches of the WA Cascades, the Bitterroots, Lewis Range,   
   and as far south as the peaks of the Absaroka and Tetons. A brief   
   ridge of high pressure builds in Saturday night before the round   
   of Pacific moisture arrives Sunday morning. Temperatures will be a   
   little milder this time around, confining most snowfall to the more   
   remote reaches of the Cascades. Pacific moisture will spill over   
   into the Northern Rockies Sunday night as the next atmospheric   
   river arrives on Monday. The Monday AR will be more intense with a   
   plume of >99th climatological PWATs engulfing much of the Pacific   
   Northwest by Monday afternoon. While the moisture influx is more   
   extensive, the strength of the WAA will keep snowfall to the more   
   remote reaches of the Cascades. However, moisture that spills over   
   into the Bitterroots and Lewis Range will have enough cold air to   
   support locally heavy snowfall. Over this weekend and through   
   Monday, WPC probabilities show moderate-to-high chances (50-80%)   
   for snowfall totals >12" in the WA Cascades above 5,000ft and along   
   the Lewis Range, which does include Glacier NP. Expect any   
   mountain passes that remain open to contend with potential closures   
   this weekend and into early next week.   
      
   ...Northern Plains & Midwest...   
   Days 1-2...   
      
   Height falls ahead of an approaching 500mb vorticity maximum will   
   coincide with the divergent left-exit region of a 250mb jet streak   
   over the Northern Plains to support the development of low pressure   
   early this morning. A narrow band of 850mb WAA and FGEN over   
   eastern MT will pivot south and east towards southern ND and become   
   responsible for the initial band of snow this morning. As low   
   pressure deepens, a more organized 850mb low will form over   
   southern SD and central NE. A strengthening 850mb LLJ will direct a   
   surge of WAA in the 850-700mb layer ahead of the 850mb low.   
   Combined with a healthy 290K isentropic ascent amid SWrly flow, and   
   a moistening DGZ will ensue over southeast SD, northern IA, and   
   southern MN and periods of heavy snow will develop. WPC's Snowband   
   Probability Tracker depicts the potential for >1"/hr snowfall   
   rates over southeast SD beginning around midday and continuing over   
   northern IA through Saturday evening. After 00Z Sunday, the 850mb   
   low will weaken, taking on a positive tilt and becoming an open   
   wave. Light-to-moderate snow is expected through Saturday night   
   over northern IL and southern WI (including the Milwaukee and   
   Chicago metro areas), with light snow possible across the Great   
   Lakes on Sunday.   
      
   WPC probabilities show northern IA as having the best odds of   
   seeing the heaviest snowfall of the event with moderate chances   
   (40-60%) for snowfall totals >6". Probabilities suggest I-35   
   located north of Des Moines and south of I-90 have low chances   
   (10-20%) for localized amounts over 8". Elsewhere, the area   
   spanning Sioux Falls on south and east through southern MN and   
   eastern ND all sport >50% chances for >4" of snowfall. The WSSI   
   shows Minor Impacts from the Sioux Falls area of southeast SD to as   
   far east as the Milwaukee/Chicago metro areas due to the snowfall   
   Saturday night into Sunday morning. Across eastern MT and southwest   
   ND, WPC probabilities show low- to- moderate chances (30-50%) for   
   snowfall >2", but probabilities for >4" are generally <10%,   
   implying that most totals are likely to range between 1-4" through   
   Saturday afternoon.   
      
   It is worth noting bitterly cold temperatures will follow in wake   
   of this system Saturday night and through Sunday. By Sunday   
   morning, temperatures will be in the single digits across much of   
   the Midwest and lows below zero Sunday night. Any snow that falls   
   will likely stick around for a couple days, resulting in daily   
   recurrences of icy roads and the potential for black ice.   
      
   ...Great Lakes & Northeast...   
   Days 1-3...   
      
   A series of upper level disturbances tracking across the Great   
   Lakes and into the Northeast will cause both LES bands and some   
   synoptically-focred snow across these regions this weekend and into   
   early next week. Some LES streamers off Lakes Superior, Erie, and   
   Ontario will keep accumulating snow in the forecast in the usual   
   snow belts of Michigan's U.P., the "Tip of the Mitt" in Michigan,   
   and across western NY. By Sunday morning the upper trough   
   responsible for the Midwest storm on Saturday will make its way   
   through these regions with light-to-moderate snowfall across   
   Michigan and much of the Northeast (minus the I-95 corridor   
   megalopolis). Most snowfall totals will range between 1-4",   
   although some of the LES belts may manage to see some snowfall   
   totals eclipse 4" on Sunday. It is possible an inverted trough axis   
   over the Gulf of Maine could produce locally heavy snow along the   
   coast of ME, but the trough is a progressive one and should limit   
   totals from being overly heavy (1-4" most likely). Lastly, while   
   high pressure builds in over the Northeast on Monday, an Alberta   
   Clipper makes its way toward the Upper great Lakes by Monday   
   evening with more light-to-moderate snow expected.   
      
   WPC probabilities over the next three days (Sat-Sun-Mon) show   
   moderate-to-high chances (50-80%) for snowfall totals >4" in the   
   typical LES belts of Michigan's U.P., northern Michigan, and   
   downwind of Lakes Erie and Ontario. When it comes to >8" of   
   snowfall, it is the eastern Michigan U.P. and northwest Michigan   
   where low-to-moderate chances (30-50%) are present. The WSSI shows   
   Minor Impact potential downwind of Lakes Erie and Ontario, which   
   does include the Buffalo metro area.   
      
   ...Southern Appalachians...   
   Days 2-3...   
      
   A quick moving 500mb trough will track from the TN Valley Sunday   
   night to the Southeast Coast by Monday afternoon. 500mb PVA ahead   
   of the upper trough will be paired with easterly low-level flow   
   that allows for some upslope enhancement along the southern   
   Appalachians. Snow will be at its heaviest Monday morning but taper   
   off by Monday evening. WPC probabilities show low-to-moderate   
   chances (30-50%) for snowfall totals >2" in portions of the VA/NC   
   Blue Ridge and Potomac Highlands of WV. Some localized totals could   
   top 4" in the VA/NC Blue Ridge.   
      
      
   Mullinax   
      
      
      
      
   $$   
      
   = = =   
   To unsubscribe from WX-STORM and you already have a login, go to   
   https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email   
   Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.   
      
   --- SBBSecho 3.28-Linux   
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)   
   SEEN-BY: 4/0 19/10 88/0 90/0 93/1 104/119 105/81 106/201 114/10 120/302   
   SEEN-BY: 128/187 129/14 153/757 7715 154/10 30 50 110 700 218/700   
   SEEN-BY: 218/840 220/10 20 30 90 221/1 6 360 226/18 30 44 50 227/114   
   SEEN-BY: 229/110 134 206 300 307 317 400 426 428 470 664 700 705 266/512   
   SEEN-BY: 291/111 301/1 320/219 322/757 335/364 341/66 200 342/200   
   SEEN-BY: 396/45 460/58 633/280 712/848 880/1 900/0 102 106 902/0 19   
   SEEN-BY: 902/26 904/0 13 905/0 2320/0 105 304 3634/12 5019/40 5020/400   
   SEEN-BY: 5075/35   
   PATH: 2320/105 154/10 221/6 341/66 902/26 229/426