BBS: TELESC.NET.BR Assunto: HVYSNOW: Probabilistic Heavy Snow And Icing Discussion De: COD Weather Processor Data: Sun, 15 Mar 2026 08:01:44 +0000 ----------------------------------------------------------- FOUS11 KWBC 150801 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 401 AM EDT Sun Mar 15 2026 Valid 12Z Sun Mar 15 2026 - 12Z Wed Mar 18 2026 ...Northern High Plains through the Great Lakes...=20 Days 1-3... ...Blizzard expected this weekend with widespread major impacts=20 and record-breaking snowfall for portions of the Upper Midwest and=20 Great Lakes... Confidence continues to be high for a widespread major winter=20 storm across the Upper Midwest and Great Lakes as a lee surface=20 low lifts northeast and rapidly deepens into an increasingly moist=20 column. Snowfall from Minnesota through Wisconsin and northern Michigan, including the U.P, will breach 12" in many locations with areas of northern WI into the U.P. likely to exceed 24" by the storms closure. Current WV satellite and UA analysis indicates a maturing synoptic evolution with a digging shortwave across WY and an attendant=20 surface low currently analyzed over the western High Plains of=20 Kansas. As the shortwave trough digs further to the southeast, flow will become increasingly meridional over the Central Plains to=20 Mississippi Valley with the trough axis forecast to tilt neutral to eventually negative with the 5H height pattern expected to close off near or over IA by later this evening. Surface low will trek northeast over the course of Sunday, intensifying slowly as it migrates towards the southern edge of Lake Michigan by nightfall. As the upper pattern closes off and takes on the negative trough orientation, surface low will rapidly intensifying as it begins to enter into its full maturation phase as the primary heights from 850mb to 500mb become more vertically stacked into Monday morning. The cyclone will finally reach occlusion phase by Monday afternoon, but surface low pressure will likely be down into the upper 970s by this juncture over the western Great Lakes, solidifying its presence with an all-out blizzard for a large chunk of the Midwest and Great Lakes region. Moisture convergence occurring during the=20 storms life cycle emanating from the decaying AR pushing east, and a budding theta-e ridge arcing northward on intensifying=20 WAA/southerly flow out of the Gulf will help provide substantial=20 deep layer moisture poleward, as far north as the western Ontario=20 Province in Canada, a testament to the overall fortitude of this=20 disturbance. The overlap of robust deep layer ascent with=20 maximizing moisture return will deepen the low substantially, and=20 aid in the expansion of a considerable precipitation shield, with=20 heavy snow arcing from SD through the Great Lakes already as of the pre-dawn hours Sunday. Precip field will slowly pivot northeast=20 while continuing through D2 as the surface low moves into Ontario=20 by 00Z/Tuesday. Little change in the relevant synoptic details referenced in the=20 last forecast as guidance remains steadfast in all facets of this=20 storms anticipated evolution. The synoptic setup is extremely=20 favorable for a classic Midwest winter storm with widespread=20 intense snowfall. Embedded bands with snowfall rates of 1-3"/hr are expected as reflected by high potential for CSI and even CI in=20 model cross- sections Sunday aftn into Monday which drives intense=20 omega into the TROWAL. There remains high confidence in a laterally translating band of heavy snow from SD into MN Sunday morning,=20 with the environment transiting into one that matches the=20 conceptual model for a pivoting band over eastern MN and=20 WI/Michigan U.P. Sunday evening into Monday. It is in this area=20 where the heaviest snowfall is expected, and potentially record, or near- record 2-day snowfall is possible from eastern MN through WI and northern MI. Elsewhere, snowfall rates of 1"/hr or more are=20 still likely at times, just with lesser duration. These snowfall=20 rates combined with gusty winds reaching up to 60 mph will create=20 blizzard and near-blizzard conditions and whiteouts, with major to=20 extreme impacts progged by the recent WSSI-P. Even in areas that=20 get lower snow totals, the blowing snow potential will still result in difficult travel, and it is likely that most forms of=20 transportation will be treacherous at best, and impossible at=20 worst, through the event across a large area from Montana to=20 Michigan, and everywhere in between. Event-total snowfall is likely to be extreme in some areas. This is reflected by 72-hr WPC probabilities (ending 12Z Tuesday) that are high (>70%) for at least 12" from southeast MN to points northeast through north- central WI, and the entirety of the U.P. of MI.=20 Where snowfall is most prolific, likely in northeastern WI and the U.P of MI, WPC probabilities indicate a 70-90+% chance of at least 24", and localized totals of 3-4 feet are possible before this=20 event ends with the maxima positioned across the Huron Mountains=20 downwind of Lake Superior. This could result in record snowfall in=20 some places, and with SLRs being near to slightly below climo,=20 combined with the strong winds, power outages and long- lasting=20 impacts are expected. For these reasons, Winter storm key messages=20 are in effect, and are linked below (Key Message 1). After 00Z Tuesday, snowfall rates will be waning rapidly in direct association with the storm, transitioning more and more to lake- effect snows downwind of all of the lakes. Pronounced CAA on NW=20 flow in its wake could result in some lake effect snow in the=20 favored NW snow belts downstream of all the Great Lakes. WPC=20 probabilities are moderate (50%) for at least 4" of snow from LES=20 in SW MI, as well as along the Chautauqua Ridge and into the Tug=20 Hill Plateau. Additional heavy snow will occur near Marquette, MI=20 as well, adding onto the extreme snowfall event there the next few=20 days bring storm and LES combination totals towards the 4-5ft range by Tuesday afternoon. The lake- effect will continue into Tuesday=20 morning before largely dissipating. On the S/SE side of this snowfall swath, an axis of mixed=20 precipitation is likely, leading to icing accretion from central IA through southern WI and into the northern mit in lower MI. The=20 most significant icing is expected for the northern mit of MI=20 where WPC probabilities for at least 0.25" of ice have settled=20 between 40-70%, and the axis of higher probabilities for at least=20 0.10" of ice have extended back into southern WI. ...Central Appalachians... Powerful cyclone over the Great Lakes will provide a strong cold front trailing the primary surface low as it migrates eastward through much of the country east of the Mississippi. Once the cold front advances beyond the Appalachian front, strong cold air advection (CAA) regime will transpire with rain changing to snow for the mountains of western PA down through western MD and the adjacent WV Highlands. Elevations >2000ft will see some snowfall with the greatest accums focused over areas >2500ft, a general climo output for this type of evolution. WPC probabilities for >4" of snowfall are between 20-40% for the entire Appalachian chain of western PA down through WV. Maxima of 40-60% is located over the Canaan Valley down into Snowshoe, WV where some deterministic output are printing out upwards of 6-8" of high ratio snowfall post-fropa. Setup and magnitude of the upslope flow is classic for this scenario allowing for growing confidence in at least minor impacts for the terrain of the Mid Atlantic.=20 Weiss/Kleebauer ...Winter Storm Key Messages are in effect. Please see current=20 Key Messages below... https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!5Mz4bRZVZZ9RVDTb1sBqsu4WHXcb-lCcyrgMk_jU8_b5T= PaB831GnEHgCTyaR_6m85bP8GQekWHF3E-8MTlD2oSyFkY$=20 $$ =3D =3D =3D 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]