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|  Message 40109  |
|  COD Weather Processor to wx-storm@lists.illinois.edu  |
|  HVYSNOW: Probabilistic Heavy Snow And Ic  |
|  06 Jan 26 20:40:21  |
 TZUTC: 0000 MSGID: 168312.weather@1:2320/105 2dc53ab3 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 062040 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 340 PM EST Tue Jan 6 2026 Valid 00Z Wed Jan 07 2026 - 00Z Sat Jan 10 2026 ...Northeast... Day 1... An amplifying shortwave along with a trailing shortwave over the Upper Midwest this evening will move steadily eastward into/through the Northeast overnight and early tomorrow morning. As a modest jet streak moves off the Mid-Atlantic coast this evening, broad lift on the poleward side of the jet will help promote an expanding area of precipitation across the region atop a marginal to cold environment. At the surface, the dueling mid-level shortwaves will help take a lead surface low over western NY (BUF to ART) overnight and a newly developing surface low near southeast Mass by 12Z Wed that will lift toward Nova Scotia through the afternoon. Given the marginal temperatures at precip onset over at least some of the interior and WAA aloft, a mix of freezing rain and some sleet to the south and mostly snow to the north (along the Canadian border) is likely as the decaying lead low allows a northerly fetch to continue to bring in some colder air to northern locations. The system will exit the region by tomorrow evening given the progressive flow. For areas that receive mostly snow (the higher elevations of the Adirondacks and northern New England), WPC probabilities for at least 4 inches of snow are modest at 10-40% with most areas likely seeing 2-3 inches of snow. Along and south of I-90, a mix of mostly freezing rain but some sleet is likely. WPC probabilities of at least 0.10" icing are highest (>50%) in MA along/north of I-90 and along Route 2, as well as into the southern Green Mountains in VT and into southern NH. Localized amounts near 0.25" are possible. ...Olympics, Cascades, Great Basin, and Northern/Central Rockies... Days 1-3... The strong jet across the North Pacific will dip into the Pac NW and weaken, but still bring a modest influx of moisture to the region via several embedded shortwaves. Lead system enters tonight via a 120kt jet streak with snow to the Cascades and northern Rockies that will sink southward as the jet digs and dips through the Great Basin. Snow levels initially around 3000-4000ft will lower overnight to below 2000ft (WA and eastward) and 3000ft (OR to ID) by tomorrow morning, with another surge in moisture thereafter as the second shortwave moves in from the Pacific. Snow levels will continue to lower to as low as 750-1000ft by early Thursday as precipitation lightens and is increasingly favored in the terrain. However, this will bring impactful snow to the passes and at least some light snow to some higher lowland areas around 1000ft. Precipitation should end in the PacNW by Friday afternoon. WPC probabilities are >50% for at least 8 inches of snow above 1000-2000ft through the WA/OR Cascades and for at least 18 inches of snow above 2000-3000ft. Total snow for the highest peaks may eclipse 3-4ft. From the northern Rockies southward to the Wasatch and WY ranges, moisture associated with the Pacific intrusion will still be modest but sufficient enough to capitalize on upslope enhancement into the terrain, especially over Idaho and northwestern MT D1 then through western WY and eventually the Wasatch as the moisture and trough sink southward and eastward. WPC probabilities for at least 12 inches of snow are >50% above 4000-5000ft (north), 7000ft (WY), and 7000-8000ft (Wasatch). ...Four Corners States... Days 2-3... A vigorous shortwave digging southeast from the Pacific Northwest will amplify rapidly as it approaches the Four Corners states (potentially closing off over the high plains of southeast CO and northeast NM or vicinity) Thursday into Friday, before ejecting eastward into the central Plains Friday night into Saturday. As this occurs, a strengthening 120kt+ 250mb jet overspreading the southern and central Plains will begin to arc poleward, placing the left exit region in the vicinity of the central and southern Rockies. The overlap of left exit region diffluence with mid-level height falls will likely lead to lee side cyclogenesis Thursday evening, within a column that, while will feature generally normal to below normal PWs, will saturate in response to increasing low- level easterly flow around the strengthening surface low. With steep lapse rates aloft helping to cool the column, and flow becoming increasingly favorable to upslope into the terrain, confidence is increasing for a more significant snow event for much of the central and southern Rockies into the High Plains of CO/NM, including the I-25 corridor (particularly from Denver to Colorado Springs) which has experienced a relative dearth of snowfall so far this season. While adjustments in the forecast are likely (and the latest trends suggest those adjustments are likely to be upward), current WPC snow probabilities now indicate a high risk (>70% chance) for storm total accumulations of 8+ inches of snow across much of the CO Rockies (including the Front Range), portions of the Wasatch, and southward into the higher elevations of northeast AZ and northwest NM. The lower elevations of I-25 and into the High Plains now have a 30-60% chance of 4+ inches, although locally higher amounts, potentially in excess of 8 inches, are also possible across western portions of the Palmer Divide and Raton Mesa. Fracasso/Miller/Weiss $$ = = = 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: 19/10 104/119 105/81 106/201 114/10 120/302 128/187 129/14 SEEN-BY: 153/757 7715 154/10 30 50 110 700 218/700 840 220/10 20 30 SEEN-BY: 220/70 90 221/1 6 360 226/17 18 30 44 50 227/114 229/110 SEEN-BY: 229/134 206 275 300 307 317 400 426 428 470 664 700 705 266/512 SEEN-BY: 267/800 291/111 301/1 320/219 322/757 335/364 341/66 342/200 SEEN-BY: 396/45 460/58 633/280 712/848 770/1 100 340 350 772/210 220 SEEN-BY: 772/230 902/26 2320/0 105 304 3634/12 5020/400 5075/35 PATH: 2320/105 154/10 221/6 218/840 770/1 633/280 229/426 |
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