BBS: TELESC.NET.BR Assunto: HVYSNOW: Probabilistic Heavy Snow And Icing Discussion De: COD Weather Processor Data: Fri, 20 Mar 2026 20:18:10 +0000 ----------------------------------------------------------- FOUS11 KWBC 202018 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 418 PM EDT Fri Mar 20 2026 Valid 00Z Sat Mar 21 2026 - 00Z Tue Mar 24 2026 ...Northeast... Days 1-3... A clipper will move into the Northeast Saturday night bringing a swath of accumulating snowfall to Upstate NY into Northern New England. Still some uncertainty with the exact track of this system, which will impact where the heaviest swath of QPF is and where the rain/snow line sets up. The higher elevations are most favored for higher snowfall totals, but strong WAA should support a period of moderate to locally heavy precipitation. This should allow snow even down to the lower elevations of northern New England, especially Saturday night into early Sunday. Snow ratios from the NBM are likely too high with this system. While snow should be coming down at a decent clip for a stretch, the strongest lift appears to be mainly centered below the DGZ, which should cap snowfall ratios. Then during the daylight hours the late March sun will play a role in lowering ratios further. In fact, where snow is falling at a lighter clip we probably won't see much accumulation during the daytime, with accumulations focused in either the highest terrain or where snow is falling at a heavy enough clip to overcome the marginal temperatures and higher sun angle. The latest WPC snowfall probabilities have increased for the Saturday night to Sunday timeframe. The probability of exceeding 4" in the 24hr period ending 00z Monday are generally 40-80% from Upstate NY into central to northern VT/NH and western ME. The highest probabilities are in the higher terrain, but values of 30-50% even get into the lower elevation areas. The probabilities of 6" are 30-60%, with 8" exceedance probabilities as high as 30-50% in the White Mountains of NH. These probabilities seem reasonable, with exact snowfall totals dependent on the specific track of the system. This is a scenario where the higher terrain has the highest probabilities (and thus confidence) in seeing greater snowfall totals, but there is still a lower risk of impactful snow getting into some of the lower elevations if a snowfall band is able to move into these areas overnight or early morning and is heavy enough to overcome the marginal temperatures. A bit more uncertainty exists on Monday as a coastal low tries to develop offshore New England. By this time it will be cold enough over northern New England for snow, but if precipitation intensity is light then the high sun angle will likely limit accumulation. However, a broader and/or more intense snow shield would be capable of producing additional accumulating snowfall. Models have been fluctuating regarding this low and inland precipitation extent...although most 12z models shifted lighter with QPF. Even the AIFS, which has been more consistently on the wetter side of the QPF spectrum, did back off at 12z. There is still time for this to change, but the probabilities of impactful snowfall Monday appear to be decreasing, but still need to continue to monitor. The chances for significant icing across the CONUS is less than 10 percent. Chenard $$ = = = 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]