A shortwave with an associated cold front crossed the region during the morning hours of January 20th. Scattered to numerous snow showers were able to develop thanks to sufficient moisture in the dendritic growth layer, along with jet-assisted ascent.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS PBZ wrote it up.
A shortwave with an associated cold front crossed the region during the morning hours of January 20th. Scattered to numerous snow showers were able to develop thanks to sufficient moisture in the dendritic growth layer, along with jet-assisted ascent. A few inches of snow were able to accumulate in some areas.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Pittsburgh, PA wrote its last area forecast discussion before the first event at Jan 19, 11:26 PM EST, 34 minutes earlier.
Area Forecast Discussion National Weather Service Pittsburgh PA 1126 PM EST Tue Jan 19 2021 .SYNOPSIS... Accumulating snow showers are likely through Wednesday, with highest amounts in the eastern ridges and I-80 corridor. An active pattern should yield additional precipitation chances mainly north of Pittsburgh through Friday. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Made a few adjustments slowing initial onset of POPs and snow accumulation based on recent upper air charts/soundings, sfc obs, and near term model data. Previous...An incoming Great Lakes shortwave as noted in recent IR imagery should support increased cloud cover and the eventual onset of snow showers from north to south through the period. Sufficient moisture advection ahead of the aforementioned trough should prime the boundary layer and support a period of efficient snowfall rates as notable cold, mid-level temperature steepens lapse rates through the dendritic growth zone. Nwly flow developing in the wake of the shortwave should then promote both lake and terrain enhancement; thus higher snowfall totals are anticipated along the I-80 corridor, with advisory level snowfall progged for the eastern ridges. The remainder of the forecast area should remain below advisory criteria (3 inches) due to the progressive nature of the disturbance and intrusion of mid-level dry air toward dawn. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Steep llvl lapse rates in cold nwly flow should support continued snow showers through Wednesday afternoon before diminishing with a building ridge. A dry period is still pictured for Wednesday night as the ridge crosses the region. Temperatures will remain fairly close to seasonable levels, as warm advection-provided mid and upper clouds prevent a steeper temperature fall. Values may need to be lowered if less cloud cover materializes, particularly over fresh snow cover. Troughing, fairly flat in nature, will develop once again mainly over the Great Lakes Thursday as a shortwave traverses northern Michigan. On the outer periphery of this system, scattered snow showers will be possible generally near and north of I-80, where the best moisture/lift will be realized. With warm advection helping temperatures to creep a bit above climatology on Wednesday, rain may mix in with these snow showers during the daylight hours on Thursday. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Snow shower chances will continue mostly to the north and east of Pittsburgh Friday and into early Saturday. Generally flat troughing over the Great Lakes, in combination with WNW flow in the low levels, will continue to generate snow showers via lake enhancement and upslope flow. Surface high pressure and ridging aloft should then return mainly dry weather from Saturday afternoon into Sunday evening. Temperatures will remain a bit below normal during this period. Moisture and milder air will then return northward as mid-level troughing and surface low pressure ride up the Ohio Valley Sunday night into Monday. Warm advection will likely provide a mixed precipitation pattern for a time on Monday. Going with a rain/snow mix for now, but the potential for freezing rain will need to be monitored closely. Colder air will then try to sink back in and turn rain showers back to all snow by Tuesday, but again, the southward penetration of cold air is questionable at this point. Given the warm advection, fairly seasonable temperatures are pictured early next week. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... A shortwave will rush through the area tonight and drag a cold front across the area by dawn. A swath of snow showers will accompany the front before a transition to more lake enhanced snow showers after dawn. MVFR cigs/MVFR-IFR vis will be the most common restriction within the frontal snow, with potential for heavier bands of snow furthering lowering cigs/vsbys. Building high pressure will end precipitation by the aftn and slowly diminish residual stratocu. .Outlook... The next restriction chc is expected with a Thursday shortwave trough. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Winter Weather Advisory until 1 PM EST Wednesday for PAZ074-076. OH...None. WV...Winter Weather Advisory until 1 PM EST Wednesday for WVZ510>514. &&
Hazardous Weather Outlook National Weather Service Pittsburgh PA 306 AM EST Tue Jan 19 2021 PAZ074-076-WVZ510>514-200815- Westmoreland Ridges-Fayette Ridges- Ridges of Eastern Monongalia and Northwestern Preston-Preston- Eastern Preston-Western Tucker-Eastern Tucker- 306 AM EST Tue Jan 19 2021 ...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM TO 1 PM EST WEDNESDAY... This Hazardous Weather Outlook is for southwest Pennsylvania and northern West Virginia. .DAY ONE...Today and tonight. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Winter Weather Advisory. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. Please listen to NOAA Weather Radio or go to weather.gov on the Internet for more information about the following hazards. Winter Weather Advisory. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures. OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-029- 031-073-075-WVZ001>004-012-021-509-200815- Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson OH- Muskingum-Guernsey-Belmont-Noble-Monroe-Mercer-Venango-Forest- Lawrence-Butler-Clarion-Jefferson PA-Beaver-Allegheny-Armstrong- Indiana-Washington-Greene-Westmoreland-Fayette-Hancock-Brooke-Ohio- Marshall-Wetzel-Marion-Monongalia- 306 AM EST Tue Jan 19 2021 This Hazardous Weather Outlook is for east central Ohio, northwest Pennsylvania, southwest Pennsylvania, western Pennsylvania, northern West Virginia and the northern panhandle of West Virginia. .DAY ONE...Today and tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Wednesday through Monday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Weather spotters are encouraged to report significant weather conditions according to Standard Operating Procedures.
The national radar mosaic for the moment the first event began.
3 winter weather. Local standard time, as filed.
Between two and three inches of snow was observed, with the highest total near Titusville.
Four inches of snow was reported at South Timblin.
At Donegal, three inches of snow fell.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2021Every state in 2021This day in weather historyWarnings in Pennsylvania, January 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 939723, 939724, 939726.