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   FOUS11 KWBC 170743   
   QPFHSD   
      
   Probabilistic Heavy Snow and Icing Discussion   
   NWS Weather Prediction Center College Park MD   
   243 AM EST Tue Feb 17 2026   
      
   Valid 12Z Tue Feb 17 2026 - 12Z Fri Feb 20 2026   
      
      
   ...Pacific & Interior Northwest...   
   Days 1-3...   
      
   An active period of winter weather expected this week across the   
   Pacific and Interior Northwest as repeated shortwaves dive through   
   a longwave trough entrenched across the region.   
      
   Increasing southerly mid-level flow downstream of the lead   
   shortwave which will dive south along the British Columbia coast.   
   This shortwave will continue to expand southward, with the trough   
   axis finally moving onshore WA/OR Tuesday night. This impulse will   
   continue to track eastward into the Great Basin and Northern   
   Rockies on Wednesday, with a secondary shortwave moving onshore   
   immediately in its wake. This mid-level evolution will push 500mb   
   heights down below the 0.5 climatological percentile today and through   
   Wednesday morning, leading to snow levels for which the NBM   
   suggests will fall below 1,000 feet as far south as northern CA.   
   The 10th percentile (a better proxy due to steep lapse rates   
   beneath the cold core trough aloft) dropping to the surface across   
   most of the area. While the heaviest precipitation is expected   
   within surges of WAA through mid-week, this is likely to produce   
   the first light snowfall accumulations down to the valley floors   
   and lowlands of WA and OR.   
      
   For Tuesday, the heaviest precipitation is expected across OR and   
   into ID, as well as the southern WA Cascades. Here, the IVT will   
   maximize within the broad WAA plume and within broad mid-level   
   divergence/height falls downstream of the lead shortwave trough.   
   Additionally, S/SW flow will impinge favorably into the Cascades   
   for upslope enhancement, with snow levels falling well below pass   
   levels. This includes potentially down to I-5 through the   
   Willamette Valley. The heaviest snow is expected above 2,000 ft,   
   where WPC probabilities are high (>70%) for Tuesday and low (30%)   
   Wednesday for 4+ inches each day, leading to locally more than 12   
   inches of snowfall through 00Z/Thursday. This will create hazardous   
   travel, especially across Santiam, Willamette, and Siskiyou   
   Passes. Light snow accumulations are expected even onto the coastal   
   terrain of WA/OR where there exists a 30-50% chance of at least 2   
   inches.   
      
   A brief break in precipitation is expected Tuesday night before   
   the second shortwave approaches with renewed ascent aloft and   
   moisture spreading throughout the region. Moderate to locally is   
   likely, especially across the WA/OR Cascades and surrounding   
   lowlands as snow levels again fall below 500 ft. WPC probabilities   
   for at least 1 inch of snow reach 30% even into the Portland, OR   
   metro area and surrounding Seattle, WA, with an additional 6+   
   inches of snowfall likely (70% chance) across the southern WA and   
   most of the OR Cascades.   
      
      
   ...California...   
   Days 1-3...   
      
   ...Multiple days of heavy and disruptive snowfall to affect the   
   California mountain ranges this week...   
      
   A series of potent Pacific storm systems are working together to   
   direct copious amounts of moisture at the mountain ranges of the   
   "Golden State". After snow levels steadily fell throughout the   
   night, today, another round of heavy snow is expected across just   
   about all of the CA mountain ranges as a second and more amplified   
   upper level low dives south along the West Coast. This will spike   
   onshore flow and additional moisture supply on the southern and   
   eastern flanks of the upper low. Renewed heavy snow will start out   
   across the northern California ranges Tuesday morning, then spread   
   south down the Sierra Nevada from Tuesday afternoon through Tuesday   
   night. Once again, 1-2 inch/hour rates will be common with 3-4   
   inch/hour rates possible locally. Snow levels will continue to   
   fall to around 1,000 ft in far northern California (including the   
   northern coastal range) Tuesday night, around 2,500ft in the Sierra   
   Nevada, and between 4,000ft and 5,000ft into the Transverse   
   Ranges. Snow will continue to fall across California's mountain   
   ranges trough Wednesday as yet another 500mb shortwave trough west   
   of WA continues to sustain what feels like an endless supply of   
   Pacific moisture into the Golden State. However, during the day   
   Wednesday snowfall rates could diminish in most of the mountains   
   down to light snow or even flurries at times. With the longwave   
   trough overhead, snow levels could creep down as low as 1,000ft in   
   central CA and may support minor accumulations down to 1,000ft.   
      
   On Thursday a pair of shortwaves, both moving SSE, but one   
   impacting the Northern California ranges, and the other following   
   the previous disturbances hugging the coast until it turns inland   
   over Southern California, will keep moderate snow ongoing along   
   most of California's ranges. Rates will not be quite as heavy on   
   Thursday as on previous days. Snow levels will fall in the   
   Transverse Ranges to as low as 3,500 feet Thursday morning, while   
   staying between 1,500 and 2,500 feet from the Sierra Nevada north.   
      
   California's mountain ranges welcome the snow, although it will   
   come down fast and furious through mid-week. Through the end of   
   this discussion's timeframe (12Z Fri), snowfall will be measured   
   in feet above 4,000ft along the Sierra Nevada. Several additional   
   feet of snow is forecast along Donner Pass through 12Z Friday and   
   more snow still to come. The WSSI shows a large swath of Extreme   
   Impacts (Substantial disruptions to daily life; extremely dangerous   
   travel or impossible driving conditions, extensive closures) for   
   elevations generally above 5,000ft, although some Major impacts as   
   low as 4,000ft are possible. Major to locally Extreme impacts are   
   showing up in the peaks of the San Gabriel and San Bernadino   
   mountains, with mostly Moderate-to-Major Impacts (increasingly more   
   disruptive to travel jumping from Moderate to Major). There are   
   also likely to be some Major impacts in the Coastal Range of   
   northwest CA above 2,000ft. Note that there are Minor to locally   
   Moderate Impacts expected along I-5 around Mount Shasta, signifying   
   potential travel delays for I-5 in the more elevated terrain of   
   northern CA.   
      
      
   ...Intermountain West...   
   Days 1-3...   
      
   Pacific moisture ahead of the longwave upper trough off the West   
   Coast will spill over the Cascades and Sierra Nevada and reach many   
   ranges across the Intermountain West this week that badly need the   
   boost in snowpack. With a lack of a frigid airmass ahead of this   
   healthy moisture source, the bulk of the heavy snow will be largely   
   confined to many of the taller mountain peaks. The heaviest   
   snowfall on Monday will reside in the Blue, Sawtooth, Wind River,   
   Uinta, and as far south as Mt. Charleston and the Mogollon Rim. WPC   
   72-hour probabilities are high (>70%) for snowfall totals >12" in   
   these mountain ranges through Thursday afternoon.   
      
   On Tuesday, the highly anomalous upper-low off the Pacific NW coast   
   will help to usher the initial upper low over southern CA east into   
   the Intermountain West, causing widespread height falls and a   
   larger plume of Pacific moisture to pass over the Rockies. The   
   potent closed low then heads inland over the interior NW and   
   northern Rockies on Wednesday while opening up into a trough,   
   prompting snow levels to crash and most valleys are likely to see at   
   least a coating of snow. By Thursday, much of the Intermountain   
   West will be in a lull between storm systems, as the next in the   
   series of shortwaves moves across California. Some snow will spill   
   over into much of Nevada, while areas further east see the snow   
   stop completely during the day. Snow with the shortwave over   
   California moves across the Four Corners into Thursday night and   
   Friday.   
      
   The bulk of the heavy snow will be observed in mountain ranges such   
   as the Wasatch, Bear River, Tetons, Uinta, Wind River, Mogollon   
   Rim, and CO Rockies who are forecast to receive between 1-2 feet   
   of snow (locally up to 3 feet possible). Expect Minor to Moderate   
   Impacts, per the WSSI, with travel over passes from the Lewis Range   
   and Bitterroots to as far south as the Mogollon Rim likely to   
   contend with hazardous travel conditions. Some Major Impacts are   
   showing up in the more remote peaks of these mountain regions.   
      
      
   ...Northern Plains & Upper Great Lakes...   
   Days 1-2...   
      
   A shortwave emerging from the Great Basin will track quickly to the northeast   
   today, reaching the Dakotas later this evening while also   
   strengthening in the process. As this trough becomes negatively   
   tilted and expands across the Northern Plains/Upper Midwest, it   
   will interact with the LFQ of a strengthening subtropical jet   
   streak arcing from the Desert Southwest to the Great Lakes. This   
   setup will support surface cyclogenesis Tuesday evening. This low   
   is then expected to move very slowly through Wednesday before   
   gradually filling over the western Great Lakes Thursday night.   
      
   As this low tracks slowly eastward, it will interact with   
   impressive IVT surging above the 99th climatological percentile   
   into Minnesota. The accompanying moisture and theta-e ridge axis   
   will then wrap cyclonically around the system and lift into a   
   pronounced TROWAL. The associated synoptic lift, aided by   
   increasing WAA, will expand precipitation across the northern tier   
   of the CONUS from far eastern MT through the western Great Lakes.   
   Periods of heavy snow are likely as strongly sloped FGEN driving   
   omega into the TROWAL supports heavy precipitation rates. The most   
   impressive ascent appears to intersect the DGZ, so despite this   
   being subjectively elevated (nearing 500 mb), it will support heavy   
   snow rates and dynamic cooling into a column that is initially too   
   warm to support snow. However, once precipitation changes to snow,   
   it will become heavy, supported by the WAA/FGEN beneath the TROWAL   
   and accompanying CSI evident in cross-sections, supporting rates   
   that will likely exceed 1"/hr at times (>70% chance). These   
   intense rates will be accompanied by strong and gusty winds,   
   resulting in widespread moderate impacts (30-60% chance) from ND   
   through the Arrowhead of MN. It is in this swath of the Upper   
   Midwest where there are moderate-to-high chances (50-70%) for   
   snowfall totals >6", including as far east as the northern shores   
   of MI's Upper Peninsula. Some localized areas of northern ND and   
   northern MN could see totals approach 12", but it is the MN   
   Arrowhead that will see as much as 1-2 feet of snow with localized   
   totals topping 24". The WSSI-P shows moderate chances (40-60%) for   
   locally Major Impacts (considerable disruptions; dangerous driving   
   conditions and widespread closures).   
      
   Additionally, with the pronounced WAA rotating around the surface   
   low, an area of freezing rain is also expected, especially from   
   near 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 for over 24 hours in parts of northern WI and   
   northern MI. WPC probabilities are moderate (40-70%) 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.   
      
      
   ...Northeast...   
   Day 2...   
      
   A strong surface low moving slowly across the Dakotas/Minnesota   
   Wednesday 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 heavy precipitation   
   from Upstate NY through southern/central New England.   
      
   This precipitation will expand eastward from the Great Lakes   
   Wednesday morning, then exiting off the New England coast by   
   Thursday morning. Guidance is now coming into better agreement on   
   the placement over 925-850mb layer-averaged FGEN zone over the   
   southern tier of NY, that is favoring a swath of snow just north   
   of the FGEN band. Thermally, the antecedent column is marginal to   
   support wintry precipitation, and it appears any significant   
   snowfall accumulation will be contained both to higher elevations   
   above 1,000 ft, and to where the most intense dynamic cooling can   
   overwhelm the above- freezing low levels. The most significant   
   accumulations are most likely from upstate NY into western VT where   
   conditional instability into a DGZ is just supportive enough to   
   generate locally heavy rates.   
      
   This is reflected by WPC probabilities that reach as high as   
   10-40% for 4+ inches of snow, especially in the Adirondacks and   
   Greens, with moderate probabilities (40-70%) for >2 inches   
   covering much of central New England and the northern half of   
   upstate NY. It is important to note that the WSE mean snowfall for   
   much of this area remains below the maximum values, so some   
   locally higher amounts are probable where any banding persists.   
   South of this axis of moderate to heavy snow, a corridor of icing   
   exceeding 0.1" is possible (30-50% chance) from the southern shore   
   of Lake Ontario with low chances (10-30%) for over one-quarter   
   inch.   
      
      
   ...Central Plains...   
   Day 3...   
      
   Wednesday night, 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   
   Sand Hills of NE and southern SD early Thursday morning. While   
   there is lingering spread in guidance regarding the placement of   
   this band as it forms as far west as eastern WY and tracks as far   
   east as the MO River Valley Thursday evening, 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. Latest WPC probabilities show   
   moderate chances (40-60%) for >4" of snow from eastern WY on east   
   along the NE/SD border and into southeast SD. It is worth noting   
   there are low chance probabilities (10-30%) for >8" of snowfall in   
   northern NE and southern SD. Given the strong dynamics and banding   
   potential, these are the kind of setups where seeing snowfall   
   totals are low chance over 48 hours out, but are very much within   
   reason. Residents in the Central Plains should monitor the forecast   
   from their local WFO closely in the coming days.   
      
      
   Mullinax/Weiss/Wegman   
      
      
      
      
      
   $$   
      
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