TZUTC: 0000   
   MSGID: 167506.weather@1:2320/105 2da19e0f   
   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 102035   
   QPFHSD   
      
   Probabilistic Heavy Snow and Icing Discussion   
   NWS Weather Prediction Center College Park MD   
   335 PM EST Wed Dec 10 2025   
      
   Valid 00Z Thu Dec 11 2025 - 00Z Sun Dec 14 2025   
      
      
   ...Pacific Northwest through the Northern High Plains..   
   Days 1-3...   
      
   The strong Atmospheric River (AR) will start to wane over the   
   Cascades tonight with the last push of moisture onto the coast. The   
   upper jet will wobble a bit across southern BC but keep the   
   Northwest in mild conditions with snow levels 7000-9000ft to start   
   this evening. Through the day tomorrow, increased ridging over the   
   Northeastern Pacific will allow snow levels to slip a bit,   
   especially by Thursday evening as the precipitation intensity   
   decreases. WPC probabilities for at least 8 inches of snow are >50%   
   above about 5500ft. Much colder air will dive southward east of the   
   Divide across Montana setting up a significant snowfall by Friday.   
      
   Over the High Plains, warm advection atop a cold surface boundary   
   layer will support freezing rain from northeastern MT southeastward   
   through southwestern ND into central SD on Thursday. Model QPF   
   placement/axis and amounts continue to vary across the region but   
   trended up with the latest cycle. This introduced some moderate   
   probabilities (30-60%) of at least 0.10" of icing over north central   
   SD and northeastern MT/southwestern ND.   
      
   By Day 2, ridging will push the moisture plume into British Columbia   
   but also allow a strong surface cold front to rush southward east of   
   the Divide. With a continued moisture surge up and around the Pac NW   
   (albeit less than earlier in the period but still a quite   
   respectable >90th percentile PW and IVT), snow will expand and   
   strengthen over central/eastern MT as snow ratios rise as well.   
   Strong low/mid-level FGEN may support a heavier axis of snow from   
   central to southeastern MT. Snow will continue into Saturday but   
   lift northward as the jet wobbles back to the northeast, pushing the   
   snow into northeastern MT. By Saturday afternoon upper ridging will   
   finally push inland into the Northwest, yielding drier conditions   
   for the region. For the day 2-3 period, WPC probabilities of at   
   least 4 inches of snow are >50% over a large area of Montana east of   
   the Divide, from just east of Cut Bank through Havre, southward to   
   Billings, and eastward to southeastern MT/northwestern SD. Within   
   this region, WPC probabilities for at least 8 inches of snow are   
   >40% across central MT between Havre and Billings.   
      
      
   ...Central Appalachians & Northeast...   
   Day 1...   
      
   As low pressure tracks into the St. Lawrence Valley tonight into   
   Thursday, the focus will shift from synoptically driven snowfall   
   across northern New England and interior portions of the Northeast   
   to lake effect snowfall downwind of the Great Lakes. Prior to this   
   transition, additional snowfall will be most notable across the   
   Adirondacks, Berkshires, Green, and White Mountains where WPC   
   probabilities for >6" are moderate to high (60-90%). Additionally,   
   strengthening northwesterly winds oriented perpendicular to the   
   central Appalachians will also result in significant upslope   
   snowfall through tonight and into Thursday morning. WPC   
   probabilities for >4" of snow is moderate to high (50-90%) across   
   portions of the higher terrain of WV and far western MD with   
   similar chances for >6".   
      
      
   ...Great Lakes...   
   Days 1-3...   
      
   Cold advection within cyclonic flow around the storm system   
   exiting the Northeast will result in several lake effect snow bands   
   which are likely to produce multiple rounds of moderate to heavy   
   snow the next few days. The most prominent bands will develop and   
   persist along the Chautauqua Ride and across the Tug Hill through   
   Thursday, with the band off of Lake Ontario lingering into Friday   
   as well. Lesser bands will also affect the eastern Michigan U.P.   
   and the northwest section of Michigan's Mitten with WPC   
   probabilities of total snowfall >4" of 30-70% through Friday.   
   Meanwhile, the Tug Hill Plateau sports high chances (>70%) for   
   snowfall totals topping 8", with low to moderate chances (30-60%)   
   for >12" amounts. Moderate to high chances (40-80%) of >8" also   
   remain along the Chautauqua Ridge through Friday as well.   
      
   By Day 3, a renewed shot of CAA associated with a sharpening trough   
   and embedded vort max will support additional bands of lake effect   
   snow downwind of all the Great Lakes, but especially across   
   portions of the eastern U.P. of Michigan and the northwest portion   
   of lower Michigan. Here, WPC probabilities for snowfall >4"   
   increase to 50-90%, with 20-50% probabilities of >8" even outlined   
   across a small portion of the U.P of Michigan. Low to moderate   
   probabilities of additional snowfall >4" are also highlighted   
   downwind of Lake Erie and Lake Ontario.   
      
      
   ...Midwest, Ohio Valley, & Central Appalachians...   
   Day 2...   
      
   Emanating from the Northern Rockies/High Plains system, northwest   
   flow will support a clipper system from the Midwest through the Ohio   
   Valley into the central Appalachians Thursday afternoon into Friday.   
   Models continued to struggle with the QPF axis (varying a couple   
   hundred miles northeast to southwest), with a preference toward the   
   global and AI models vs the hi-res models. Sufficient moisture   
   combined with modest forcing beneath the 140kt jet streaks and   
   within/along a low-level thermal gradient should yield several   
   inches of snow where SLRs are >12:1. Day 2 WPC probabilities of at   
   least 4 inches of snow are >30% along an axis from central IL to   
   northern/northeastern KY.   
      
      
   ...Corn Belt to the Midwest...   
   Day 3...   
      
   Broad cyclonic flow over Hudson Bay/eastern Canada will carry   
   another shortwave around its southwestern periphery Friday night   
   into Saturday from the Plains through the Corn Belt to the Midwest.   
   This will yield yet another chance of light snow for the region on   
   the heels of the previous system. WPC probabilities for at least 4   
   inches of snow on Day 3 are low for now, generally 10-30%, from Iowa   
   through central IL.   
      
      
   Fracasso/Miller/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: Capitol City Online (1:2320/105)   
   SEEN-BY: 1/19 100 16/0 19/10 37 104/119 105/81 106/201 114/10 120/302   
   SEEN-BY: 123/130 128/187 129/14 142/104 153/757 7715 154/10 30 50   
   SEEN-BY: 154/110 700 201/0 203/0 218/700 840 220/10 20 30 90 221/1   
   SEEN-BY: 221/6 360 226/18 30 44 50 227/114 229/110 134 206 300 307   
   SEEN-BY: 229/317 400 426 428 470 664 700 705 240/5832 266/512 280/5003   
   SEEN-BY: 291/111 301/1 320/119 219 319 2119 322/757 762 326/101 335/364   
   SEEN-BY: 341/66 342/200 396/45 423/81 460/58 633/280 712/848 902/26   
   SEEN-BY: 2320/0 105 304 3634/12 5020/400 5075/35   
   PATH: 2320/105 154/10 221/6 1 320/219 229/426