BBS: TELESC.NET.BR Assunto: HVYSNOW: Probabilistic Heavy Snow And Icing Discussion De: COD Weather Processor Data: Tue, 17 Mar 2026 06:25:07 +0000 ----------------------------------------------------------- FOUS11 KWBC 170624 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 224 AM EDT Tue Mar 17 2026 Valid 12Z Tue Mar 17 2026 - 12Z Fri Mar 20 2026 ...Great Lakes southeast through the Mid-Atlantic... Day 1... Strong low pressure which produced the blizzard over the Upper Midwest/Western Great Lakes will be well northeast into Canada this morning, while its trailing arctic cold front will be positioned just off the Atlantic Seaboard to start the period. Behind this low and the associated front, strong CAA on NW winds will be widespread across the Great Lakes, Central Appalachians, and Mid-Atlantic States, while a lagging but potent upper trough swings through the Ohio Valley. The overlap of this upper trough and the post-frontal NW flow will result in 3 areas of moderate to heavy snowfall today. 1) Great Lakes: CAA on the NW cyclonic flow will drop 850mb temps to as low as -20C (or slightly colder). This cold air moving across the lakes will lead to very steep lapse rates and rising inversion depths despite lake surface temperatures that are generally +5C or less according to GLERL. This will support efficient lake effect snow (LES) in the favored W/NW snow belts, and although the duration of any single bands may be modest due to the movement of the mid- level trough, heavy snow rates in excess of 1"/hr are possible (30-50%) within any LES bands. The heaviest accumulations are likely across the Tug Hill Plateau and then down towards Syracuse, where WPC probabilities are high (>70%) for at least 4 inches of snow, with locally more than 8 inches possible. 2) Central Appalachians: The persistent NW flow will generally result in a drying column across the area. However, as the mid- level trough swings overhead, it will briefly provide some additional synoptic ascent through height falls/PVA, overlapping favorable upslope flow into the terrain to produce periods of moderate to heavy snow. The nature of this snow may be more snow "showery" that continuous, limiting accumulations overall. However, snowfall rates may at times reach 1"/hr (10-30% chance) leading to locally as much as 4 inches of snow (10-30% chance) in the higher terrain of WV and into the Laurel Highlands of PA. 3) Ohio Valley to the Mid-Atlantic: As the mid-level trough swings overhead this aftn/eve, it will likely encourage some bubbling of convective snow showers and isolated snow squalls across the region. Lapse rates become impressively steep beneath this trough, and there will be just enough moisture to generate numerous convective snow showers which will move rapidly east through the evening. The SnSq parameter is high for OH/WV/PA, and lesser due to drier air farther east. While snow squalls can't be ruled out, this is more likely to manifest as scattered to numerous convective snow showers across the area. Accumulation from these will be minimal, but brief heavy snow rates and gusty winds could cause rapid changes in visibility and hazardous driving later today. The probability for significant icing across the country is less than 10%. 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 (1:2320/107) ----------------------------------------------------------- [Voltar]