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   FOUS11 KWBC 130819   
   QPFHSD   
      
   Probabilistic Heavy Snow and Icing Discussion   
   NWS Weather Prediction Center College Park MD   
   319 AM EST Fri Feb 13 2026   
      
   Valid 12Z Fri Feb 13 2026 - 12Z Mon Feb 16 2026   
      
      
   ...Central & Southern Rockies...   
   Days 1-1.5...   
      
   A broad upper-level trough lifting northeastward over Baja   
   California will continue to funnel anomalous moisture into the   
   Four Corners region today with 500-700mb Q-vector convergence over   
   the central and southern Rockies. The lack of a continental polar   
   (cP) airmass is keeping periods of snow confined to elevations   
   above 8,000ft throughout the Four Corners' mountain ranges today   
   and into early Saturday morning. 700-500mb height falls, 500mb PVA,   
   and PWs above the 90th climatological percentile will support   
   mountain snow as far south as the Gila Mountains to as far east as   
   the Sangre De Cristo range. The increased upper-level synoptic-   
   scale forcing will improve snowfall rates in the higher terrain   
   with >1"/hr rates at times. 48-hour WPC probabilities show   
   modertae-to-high chances (50-80%) for snowfall totals >4" in the   
   AZ Gila Mountains and the CO/NM Rockies, with the higher   
   confidence in snowfall >6" being above 9,000ft. In the peaks of   
   the CO Rockies and Gila Mountains, there are some low chance   
   probabilities (<30%) for snowfall totals >8" through Saturday   
   morning.   
      
      
   ...Northern New York...   
   Day 1...   
      
   A progressive 500mb vorticity max over Ontario Friday afternoon   
   will provide sufficient upper-level ascent atop a low-level warm   
   front driven by a narrow sliver of 850mb WAA. Guidance is coming   
   into better agreement on a period of moderate snow, potentially   
   falling heavily at times, along the shores of Lake Ontario on east   
   into the Tug Hill and Adirondacks Friday night. Mean flow out of   
   the NW with residual 700-300mb moisture will support lingering   
   periods of snow into the Tug Hill and Adirondacks into early   
   Saturday morning before tapering off by midday. Most snowfall is   
   likely to range between a coating-3" for much of northern New York,   
   although the Tug Hill features low chances (<20%) for localized   
   amounts >4" through Saturday morning.   
      
      
   ...Cascades & Northern Rockies...   
   Days 1-3...   
      
   An upper-level trough in the Gulf of Alaska will dive south just   
   off the coast of British Columbia and direct a plume of rich   
   Pacific moisture at the Pacific Northwest this afternoon and   
   into Saturday. A passing cold front and height falls in advance of   
   the encroaching upper trough will cause snow levels to drop as low   
   as 2,000ft in the Olympics and Cascades. Elevations in the WA   
   Cascades above 4,000ft sport the better chances for snowfall   
   amounts surpassing 6", while most elevations below 3,000ft range   
   between a coating-3". WPC probabilities for at least 4 inches of   
   snow for Stevens and Snoqualmie passes are between 40-60%. The   
   plume of Pacific moisture spills eastward into the Northern Rockies   
   with the Bitterroots, Sawtooth, and Lewis Ranges most likely to   
   receive measurable snowfall starting Friday evening and continuing   
   throughout the day Saturday. The Northern Rockies will remain   
   downstream of a robust 250mb jet streak and steady 500mb PVA   
   advection through Sunday as well, keeping snow in the forecast   
   through the weekend's conclusion. Similar to the Cascades, most   
   snowfall totals will be minor (coating-3") at the lower elevations.   
   For the more remote elevations above 5,000ft in the Bitterroots and   
   Lewis Range, 2-hour WPC probabilities show moderate-to-high chances   
   (50-80%) for snowfall totals >8" with totals surpassing 12" above   
   6,000ft in the Lewis Range. Meanwhile, as the passing cold front   
   will sinks southward over the OR Cascades, snow levels will remain   
   around 4,000ft with most heavy snowfall staying in the more   
   remote/volcanic peaks.   
      
      
   ...California...   
   Days 2.5-3...   
      
   A potent closed 500mb low west of CA will emanate healthy 500mb PVA   
   over the Golden State as early as Sunday afternoon with diffluent   
   flow at the nose of a strengthening 500mb jet streak. Increasing 850-300mb   
   moisture ahead of the trough steadily increases over northern CA   
   with periods of mountain snow unfolding in the Siskiyou/Shasta. The   
   500mb low by Sunday night is a robust one, highlighted by 500mb   
   heights per ECMWF that are below the 1st climatological percentile.   
   Ahead of the upper low, a 500-750 kg/m/s IVT will direct   
   subtropical East Pacific moisture northward into the Sierra Nevada   
   by early Monday morning with snow levels down to 5,000ft. Sunday   
   night into early Monday morning marks the beginning of a multi-day   
   barrage of heavy mountain snow throughout much of the Golden State   
   with heavy snow eventually starting to accumulate during the day   
   Monday as far south as the Transverse and Peninsula Ranges down to   
   5,000ft. See WPC's extended range discussion for more information,   
   but it is worth noting WPC's WSSI-P shows moderate-to-high chances   
   (50-70%) for Major impacts in the central and southern Sierra   
   Nevada on Presidents' Day that then jump to >70% for all of the   
   Sierra Nevada above 6,000ft by Tuesday. Residents and those   
   traveling through passes in California next week should monitor   
   the forecast closely in the coming days.   
      
      
   ...Central Appalachians & Mid-Atlantic...   
   Day 3...   
      
   ...High confidence in a moisture-latent storm system, low   
   confidence in precipitation-type from the Appalachians to the I-95   
   corridor...   
      
   A sharp 500mb trough tracking through the Lower MS Valley early   
   Sunday morning will tap into ample Gulf moisture and direct it   
   northeast into the southern and central Appalachians. In addition,   
   a strong >140kt jet streak southeast of the MA Capes is placing its   
   diffluent right-entrance region over the Mid-Atlantic, providing   
   excellent upper-level divergence aloft. Guidance is in good   
   agreement on a rather strong surface low (sub 1000mb low) tracking   
   across northern MS/AL that, according to the ECMWF, is highly   
   anomalous, with the aforementioned pressure being below the 1st   
   climatological percentile. The integrated vapor transport (IVT)   
   over the Southeast tops 750 kg/m/s, exceeding the 97.5   
   climatological percentile, and results in moderate-to-heavy   
   precipitation moving into the Mid- Atlantic Sunday morning and   
   through Sunday evening.   
      
   While there is no shortage of moisture at this system's disposal,   
   the cold airmass in advance of the storm is quite marginal. Despite   
   the presence of high pressure over New England, the temperature   
   regime associated with this high pressure is not particularly cold   
   at all. Using a combination of GEFS/EPS percentiles, 10th   
   percentile temperatures in northern MD are 32-34F, with 50th   
   percentile values in the mid 30s. Meanwhile, dew points are likely   
   to range between the upper 20s and low 30s. The resulting wet-bulb   
   temperatures at the surface tend to hover around or slightly above   
   freezing in central Appalachians, northern VA, northern MD, and the   
   DelMarVa Peninsula. With temperatures in the surface-850mb layer   
   being isothermal along the 0C isotherm to even 1-2C above freezing,   
   the potential for snowfall will be heavily dependent upon   
   elevation and dynamic cooling via strong vertical velocities and   
   heavy precipitation rates. This system is very much more of a   
   March-like storm system, where mesoscale banding and elevation are   
   the primary methods for which accumulating snow would occur.   
      
   WPC probabilities are not overly impressed at this time with <30%   
   chances for over 1" of snowfall in the central Appalachians and   
   northern Mid-Atlantic. Given the lack of a thermally-supportive   
   boundary layer via marginal wet-bulb temperatures, it will prove   
   difficult to support a widespread snow event. However, as the event   
   encroaches upon the hi-res CAMs guidance window, confidence in   
   whether a narrow swath of measurable snow from the central   
   Appalachians to the Mid-Atlantic I-95 corridor will come into   
   better focus. For now, residents in the central Appalachians and   
   Mid-Atlantic should, at minimum, expect a dreary/wet Sunday with   
   the potential for some snow mixing in over elevated terrain.   
      
      
   The probability of significant icing across the CONUS is less than   
   10 percent.   
      
      
   Mullinax   
      
      
      
      
      
      
   $$   
      
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