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Mike Powell | All | Heavy, Disruptive Snow CA |
February 18, 2026 8:37 AM * |
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FOUS11 KWBC 180838 QPFHSD Probabilistic Heavy Snow and Icing Discussion NWS Weather Prediction Center College Park MD 338 AM EST Wed Feb 18 2026 Valid 12Z Wed Feb 18 2026 - 12Z Sat Feb 21 2026 ...Pacific & Interior Northwest... Days 1-2... The longwave trough that has led to multiple days worth of accumulating snowfall looks to continue through at least Thursday morning before a upper level ridge pattern builds in late in the day Thursday and persist through Friday. Snow levels along I-5 will creep as far down as 500ft this morning and again on Thursday morning, but moderate-to-locally heavy snow will reside in the >2,000ft elevations of the OR Cascades and above 3,000ft in the WA Cascades. Farther east, the Blue Mountains on east into the Bitterroots and Sawtooths will be heavy snow above 3,000ft (Blues & Bitterroots) and above 4,000ft (Sawtooth). The heaviest snowfall will unfold in the Absaroka, Tetons, Wind River, and Bear River Ranges where they not only have the higher elevations, but also reside where the riches 700-300mb moisture source will be and beneath the diffluent left-exit region of a 250-500mb layer jet streak. WPC probabilities moderate-to-high chances (40-70%) for snowfall >12" in the peaks of these mountains ranges, as well as the peaks of the OR Cascades. In the Willamette Valley, most snowfall totals are likely to be less than 1", although some areas close to Eugene, OR could eclipse 1". Expect hazardous travel conditions in the passes of the Northern Rockies and OR Cascades through Thursday morning. ...California... Days 1-2... ...Heavy, disruptive snowfall for the California ranges to persist through Thursday... California remains ideally placed ahead of 500mb disturbances rotating around the western flank of a large longwave trough anchored over the western U.S.. Snow levels in northern CA are as low as 1,000ft, down to 2,500 ft in the Sierra Nevada, and 4,000-5,000 ft in the Transverse Ranges this morning. After a day generally upslope-driven snowfall on Wednesday, by Thursday, a phasing of shortwaves diving southeast from the Pacific NW coast will produce heavier snowfall totals throughout the CA mountain ranges. Similar to the Northwest, upper ridging will provide a break in the heavy snowfall threat beginning late Thursday and continuing into Friday. Additional snowfall of 1-2 feet are likely for the northern Sierra Nevada above 3,000ft, while in the southern Sierra, elevations above 4,000 can expect several more feet in the highest elevations. The WSSI continues to indicate widespread Major impacts are likely for just about all of the Sierra NEvada above 4,000ft Sierra Nevada through Thursday. This includes not only Donner Pass, but in the Shasta/Siskiyou where Moderate to locally Major Impacts are possible along I-5 mountain passes. In Southern California, additional snowfall accumulations over a foot are forecast above 6,000ft in the Transverse Ranges with localized amounts exceeding 2 feet possible in the peaks of the San Gabriel and San Bernadino Mountains through Thursday. ...Intermountain West/Southwest to the Rockies... Days 1-3... Pacific moisture spilling over the Cascades and Sierra-Nevada will provide a much-needed boost to the Intermountain and Rocky Mountain snowpack. Following a warm start, snow levels will drop into the valleys as the leading shortwave moves inland on Wednesday. A brief lull is expected on Thursday, except for Nevada and the Four Corners region, where the next shortwave will bring the threat for heavy mountain snow into Friday. Probabilities for storm total amounts over a foot exceed 70 percent for several areas including the high elevations of the Nevada mountains, the southern Utah mountains, the northern Arizona plateaus to the central Mogollon Rim, and much of the central Rockies - particularly the northern Utah and western Colorado ranges. ...Northern Plains & Upper Great Lakes... Days 1-2... The winter storm is ongoing this morning with heavy snow blanketing much of northern ND, northern MN, and into the northern tier of MI's Upper Peninsula. Heavy snow will continue to the north of the 500mb low as it tracks across southern MN and into northwest WI, placing the MN Arrowhead perfectly placed beneath not just the strongest upper-level divergence, but easterly flow off Lake Superior is upsloping into the Arrowhead. Snowfall rates of 1-2"/hr will be common this morning and through midday but rates should gradually weaken this afternoon and tonight. The closed low will meander over the western MI U.P. through Thursday morning, keeping periods of light-to-moderate snow in the forecast over northern MN through Thursday morning. Snowfall totals of 1-2 feet are expected in the MN Arrowhead with localized amounts surpassing 30" possible by the time this storm concludes. Additionally, with the pronounced WAA rotating around the surface low, an area of freezing rain is also expected, especially from just south of Duluth, MN eastward across northern WI and into northern MI where the warm nose will be most prevalent while surface temps remain sub-freezing. This sets the stage for a freezing rain/icing event that could last over 24 hours in parts of northern WI and northern MI. WPC probabilities are moderate-to- high (50-80%) for at least 1/10 inch of ice, with locally more than a quarter inch possible, most likely across the tip of Michigan's Mitten, mainly areas east of Grand Traverse Bay. ...Northeast... Days 1-3... A strong surface low moving slowly across the Dakotas/Minnesota today will remain entrenched within an elongated mid-level trough extending into the Mid-Atlantic states. Vorticity lobes downstream of this wave will spread northeast from the Mid-Atlantic states into the Northeast, before getting sheared to the east as mid-level flow becomes strongly confluent south of the secondary shortwave energy crossing Maine and Nova Scotia. The resultant mid- level PVA and divergence will overlap with a narrow ribbon of impressive low-level WAA to produce a stripe of moderate-to- locally heavy precipitation from Upstate NY through southern/central New England. Periods of snow will unfold from the eastern shores of Lake Ontario going east across the Tug Hill, southern tier of the Adirondacks, and as far east as the Green and Berkshires. Snowfall totals are most likely to range between a coating to 3", although some localized totals topping 4" are possible in parts of the Adirondacks and Berkshires. While the atmosphere is likely to remain below freezing in these areas, a narrow warm- nose aloft from I-90 in western NY on east through the Catskills, Poconos, and even portions of southern New England are likely to see freezing rain. The section of western NY located along and north of I90, including the Rochester area, are most concerning when it comes to travel impacts. WPC probabilities show high chances (>70%) for ice accumulations over one-tenth of an inch there and low-to- moderate chances (20-50%) for totals over one- quarter inch. This area does show the potential for Moderate Impacts (hazardous driving conditions, closures possible) today. Farther east, most ice amounts are likely to come in under a tenth of an inch from the Finger Lakes on east through southern NY (not NYC proper), the Poconos, and southern New England, but localized Minor Impacts are denoted on the WSSI today. Following a brief break in the action Thursday, a storm system strengthening in the Midwest will direct a plume of 850-300mb moisture towards the Northeast amidst increasing WAA Thursday night. To the north, high pressure over southeast Canada is building in with a weak CAD signature forming over the region. This sets the stage for yet more ice from northern into the heart of the Northeast. The Poconos, Catskills, southern Adirondacks, and Berkshires have moderate chances (40-70%) for ice accumulations over one-tenth of an inch, while many areas from the Lehigh Valley on north and east into southern New England. The higher elevations of the Poconos and Catskills could see localized ice accumulations approach one-quarter inch. In the northern Appalachians, the atmosphere will remain cold enough to support periods of snow that look to fall heavily at times Friday and into Friday evening. WPC probabilities show moderate-to- high chances (50-70%) for snowfall totals >4" in the northern Adirondacks, Green, and White mountains with low chances (10-40%) for localized amounts surpassing 8". ...Central Plains... Days 1-2... Tonight, a potent shortwave trough ejecting out of the Central Rockies will take on a negative tilt as it heads into the Central Plains. To the north of the 500mb vort max, strong 700mb Q-vector confluence will focus a narrow area of strong vertical velocities, coinciding with a pronounced TROWAL forming over the Black Hills on east into the Sand Hills of NE early Thursday morning. Most guidance agrees the impressive synoptic-scale support aloft (left- exit region of a 250mb jet streak over head) and strong SErly 850mb WAA will support heavy snowfall rates, and confidence is increasing in the Black Hills and the Sand Hills being the hardest hit. Latest WPC probabilities show moderate chances (40-60%) for >6" of snow in the Black Hills and Sand Hills on east along the NE/SD border and into southeast SD. It is worth noting there are low-to-moderate chance probabilities (20-50%) for >8" of snowfall in these areas as well. Given the strong dynamics and banding potential, localized totals surpassing 10" cannot be ruled out. Note that there does remain some uncertainty on the exact placement of the heavy snow banding, but guidance is in fairly good agreement a band of snow generating warning-level snowfall has moderate chances (40-60%) over western NE. Residents in the Central Plains should monitor the forecast from their local WFO closely in the coming days. Minor snowfall accumulating of 1-4" are possible as far west as east-central WY with some potential for 4-6" worth of snow in eastern NE to the north of the Omaha area. Mullinax/Kleebauer/Pereira $$ --- SBBSecho 3.28-Linux * Origin: Capitol City Online (618:250/1) |
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