The first significant winter storm of the season produced 6 to 12 inches of snowfall across Warren County. Over 12 inches of snow accumulated on the westernmost ridge of Somerset County, with much less elsewhere in the county.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
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 CTP wrote it up.
The first significant winter storm of the season produced 6 to 12 inches of snowfall across Warren County. Over 12 inches of snow accumulated on the westernmost ridge of Somerset County, with much less elsewhere in the county.
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 State College, PA wrote its last area forecast discussion before the first event at Nov 30, 11:15 PM EST, 1 hour 45 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 1115 PM EST Mon Nov 30 2020 .SYNOPSIS... An upper level low will lift from TN to southern Quebec by Wednesday. Colder temperatures will occur Tuesday and Wednesday accompanied by a brisk west to northwest wind and frequent snow showers across the western mountains. Several inches of snow accumulation expected on the ridges near and to the west of Route 219. Seasonably cool air and fair weather will settle in through the weekend. && .NEAR TERM /UNTIL 8 AM TUESDAY MORNING/... Snow is starting in the Laurels, but not quite yet in the NW where temps are also still in the m30s. Only slowed the arrival of precip in the NW some as they are inside the big dry slot. Clouds will keep temps up and keep the transition to snow gradual except over the Laurels where it should just start out as snow in the higher elevs and work down to the valleys in a few hours. No changes to accums for the fcst. Prev... Other than a brief mention for an hour at Meadville, there has not yet been any SN in the state. Precip shield inching ino PA. The temps are now down into the m30s in Warren Co and the Laurels, and YNG is a mix at 00Z. So it's really close to mixing and changing as the precip shield advances/expands. Wind gusts still up in the 20s in the Laurels, and will likely continue for most of the night. No changes to SF numbers. Flags look well-placed. Prev... Primary sfc low tracking into the Laurel Highlands early this afternoon while secondary deepens near triple point low over my southeast counties. Lancaster and York Counties just missed out on severe threat with strong shear and best CAPE setting up farther east, where TOR Watch is in effect for areas east and south. Steadiest rainfall has lifted east and north of central PA early this afternoon as a well defined dry slot overspreads the area this afternoon from south to north. As high clouds peel to the north, warmer/shallow low clouds are left for this afternoon and much of tonight over Central PA and the Susq Valley. Lull in the precip will persist through early tonight beneath the dry slot and within a region of shallow cold advection in as filling sfc low lifts NNE into central NY state. Again, expect some breaks in the clouds with just some patchy drizzle on the ridges or a few stray showers east of the Allegheny Front. Farther northwest, the eastern edge of cold conveyor belt/ synoptic snow will set up near the Route 219 corridor early tonight, before sliding slowly east overnight into early Tuesday along with deepening cold air. Accums start to pick up in the predawn hours in the NW Mountains, but the bulk of accumulation won't come until daylight and last into Tuesday night and Wednesday. && .SHORT TERM /8 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Really good signal for multiple bands of enhanced frontogenetical LES likely within the broader snow area early Tuesday as depicted by the HREFV2 along with good upstream fetch off Lake Huron and a decent length of Central and Western Lake Erie. Broad area of llvl instability extends well inland to the Central and NC Mountains as well, meaning that frequent snow showers (open cellular) of varying intensity are expected over much of central and north central PA throughout the day Tuesday, Compact mid and upper short waves moving through the base of upper low lifting northward across the Alleghenies Tuesday morning will lead to some brief periods of mod to heavy snow near and to the west of a line from KJST to KFIG and KELZ. Winter Weather Advisory (beginning at 09Z Tuesday) is well placed, to include Mckean, Elk and Clearfield counties where storm total snowfall should be in the 2-5 inch range, with the highest totals near and to the West of Route 219. Rain showers early Tuesday morning to the SE of the Allegheny Front will gradually mix with and change to mainly snow showers during the day. Storm total snowfall has ramped up a bit over Warren County with 10-14" amounts expected over the west/northwest. Despite duration event, these looks sufficient to push the area into Warning criteria, and have upgraded existing Winter Weather Advisory to Winter Storm Warning for snow for Warren county. Elsewhere, snow amounts are similar to previous, from this one- two punch of synoptic/cold conveyor belt, then LES/Upslope enhanced snows...3-5 inches across the Laurels and 4-8 inches across much of McKean County. The snow will likely impact both commutes AM and PM on Tues. Daytime may keep the ratios/numbers down some if we can manage to get above 32F. Chance of precipitation will be minimal to the SE of Interstate 81 on Tuesday. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... For this evening update, the PoPs are lower than prev fcsts in many of the periods. The potential phasing of the nrn and srn streams for a decent storm this weekend is just not working out. They appear to be separated by just enough time/distance as they pass thru the area that Central PA may be largely dry over the weekend. However, the position of the jet streaks will still keep us looking closely for the next few days. The W/NW flow will keep a low chc 20-30 PoPs in the fcst for the NW half of the area. Temps look rather seasonable for Thurs-Mon. Prev... Lake effect snow showers and localized squalls will continue Tuesday night into early Wednesday before fading into Wednesday evening. Additional accumulations should range between 1 and 3 inches over the Laurel Highlands and NW Alleghenies (along and west of US219) with locally higher amounts (3-6" range) possible in the primary and secondary NW PA snowbelts and ridgetops in Cambria/Somerset Counties. Travel disruptions are likely to continue with a winter storm warning (Warren Co.) and winter weather advisory remaining in effect. It will be seasonably cold and blustery with wind chills in the 20s and 30s a better indicator of what it will feel like outside. Max temps should bottom out Wednesday and trend modestly warmer into the weekend. Thursday looks dry before the pattern turns more active and unsettled from Friday into early next week. A pair of upper level troughs carving out over the Eastern U.S. should ensure a prolonged stretch of seasonably cool/near average to slightly cooler than average sensible weather in CPA into next week. For the time being, it seems the western and northern Alleghenies have the best shot seeing some snow Friday PM-early Saturday with some lake enhancement. More uncertainty late in the weekend into early next week owing to how the second upper trough evolves or closes off but higher POPs are again shaded over the Allegheny mtns. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Rain and snow now starting to wrap around into the western airspace. Expect a prolonged period of IFR or below across the western 1/3 of the airspace with wrap- around snow transitioning to lake- effect/orographic snow showers overnight and through Tuesday. Winds will increase with gusts over 25kts across the western 1/2 of the airspace by Tuesday morning. Mainly VFR expected over the southeast overnight and Tuesday. Outlook... Wed...Ceiling restrictions possible NW, otherwise VFR. Thu...Mainly VFR conditions. Fri-Sat...Chance of rain and snow showers especially over the western airspace. && .CLIMATE... Top-5 warmest November tracking at Harrisburg with an average temperature of 49.8 degrees (+5.6F). Above average temperatures to close out the month should ensure a top-3 finish. Here are the rankings through 11/29: 1. 51.3 in 1931 2. 50.0 in 1975 3. 49.8 in 2020 4. 49.5 in 2015 5. 49.3 in 1999 && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 4 AM Tuesday to noon EST Wednesday for PAZ005-010-017. Winter Storm Warning until noon EST Wednesday for PAZ004. Winter Weather Advisory until 7 AM EST Wednesday for PAZ024- 033. && SYNOPSIS...DeVoir/Dangelo NEAR TERM...DeVoir/Dangelo SHORT TERM...DeVoir/Dangelo/Martin LONG TERM...Steinbugl AVIATION...Steinbugl/Travis CLIMATE...
Hazardous Weather Outlook National Weather Service State College PA 102 PM EST Mon Nov 30 2020 PAZ024-033-011815- Cambria-Somerset- 102 PM EST Mon Nov 30 2020 ...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 7 AM EST WEDNESDAY... This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Winter Weather Advisory. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Winter Weather Advisory. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ004-011815- Warren- 102 PM EST Mon Nov 30 2020 ...WINTER STORM WARNING IN EFFECT FROM MIDNIGHT TONIGHT TO NOON EST WEDNESDAY... This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Winter Storm Warning. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Winter Storm Warning. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ005-010-017-011815- McKean-Elk-Clearfield- 102 PM EST Mon Nov 30 2020 ...WINTER WEATHER ADVISORY IN EFFECT FROM 4 AM TUESDAY TO NOON EST WEDNESDAY... This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Winter Weather Advisory. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. Please listen to NOAA Weather Radio or go to weather.gov/StateCollege on the internet for more information about the following hazards. Winter Weather Advisory. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather. PAZ006-011-012-018-019-025>028-034>037-041-042-045-046-049>053- 056>059-063>066-011815- Potter-Cameron-Northern Clinton-Northern Centre-Southern Centre- Blair-Huntingdon-Mifflin-Juniata-Bedford-Fulton-Franklin-Tioga- Northern Lycoming-Sullivan-Southern Clinton-Southern Lycoming-Union- Snyder-Montour-Northumberland-Columbia-Perry-Dauphin-Schuylkill- Lebanon-Cumberland-Adams-York-Lancaster- 102 PM EST Mon Nov 30 2020 This Hazardous Weather Outlook is for central Pennsylvania. .DAY ONE...This afternoon and tonight. The probability for widespread hazardous weather is low. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday. No hazardous weather is expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The national radar mosaic for the moment the first event began.
1 winter storm, 1 winter weather. Local standard time, as filed.
A Winter Storm produced 6 to 12 inches of snow across Warren County from December 1 into early December 2, 2020.
Upslope snows produced 12 to 14 inches of snow on Laurel Ridge in westernmost Somerset County from December 1 into early December 2, 2020. Elsewhere in the county, snowfall was significantly less.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2020Every state in 2020This day in weather historyWarnings in Pennsylvania, December 2020
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: 933047, 935546.