Low pressure developed over the Gulf Coast states and progressed northeastward and off the Carolina coast on February 18, 2021, pushing a swath of generally light snow across central Pennsylvania. The highest snowfall totals occurred near the Mason-Dixon line in southern York and southern Lancaster counties, where 6 to 9 inches of snow accumulated.
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.
Low pressure developed over the Gulf Coast states and progressed northeastward and off the Carolina coast on February 18, 2021, pushing a swath of generally light snow across central Pennsylvania. The highest snowfall totals occurred near the Mason-Dixon line in southern York and southern Lancaster counties, where 6 to 9 inches of snow accumulated.
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 Feb 17, 11:04 PM EST, 1 hour 56 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 1104 PM EST Wed Feb 17 2021 .SYNOPSIS... A winter storm will bring widespread accumulating snow from late tonight through early Friday. Leftover snow showers Friday afternoon will fade into the weekend with below normal temperatures. A fast moving system may bring a period of rain and snow from late Sunday night through Monday. Beyond that, the pattern through the end of February looks less stormy with a temperature outlook that tilts the odds toward near to above average readings. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... Late evening radar loop is showing a narrow band of light snow extending from the Ohio Valley to near KUNV at 04Z associated with fgen forcing beneath right entrance of jet streak over the Grt Lks. Near term models indicate this band of light snow will expand east to the area around KIPT by 06Z. By late tonight, expect light snow to increase in coverage, as deep southerly flow overruns cold, stable air mass across Pa. A blend of latest model guidance supports snow accums by dawn ranging from a dusting to 2 inches, with the highest amounts over the Laurel Highlands and south central mountains. Little change in temperatures overnight under thickening cloud cover, with lows ranging from the mid teens over the northern mountains, to the low 20s in the valleys south and east of the Allegheny Plateau. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Main messaging is for a long duration light to moderate snowfall Thursday into Thursday night, associated with deep southerly flow overrunning cold stable air mass linked to surface high over northern New England. Model guidance indicates the strongest fgen forcing and heaviest snow rates will pass just south of the forecast area. HREF indicates low probs of 1+ inch/hr rates, but does support a period of moderate snow intensity across the southern third of the forecast area, roughly between 8 am and 1 pm. After that, a nearly saturated 0-3km layer and upsloping easterly flow, combined with modest warm advection ahead of upstream trough, should result in widespread light snow Thursday afternoon into Thursday night. Model soundings indicate a bit of sleet is possible south of the Pa turnpike Thursday PM. Only very minor tweaks made to previous snow amounts based on latest WPC superensemble and NBM qpf. Most likely accumulations by Friday morning range from 1-2 inches over Warren County, to around 6 inches south of I-80. Any lingering light snow ends by Friday afternoon, but some lake-effect and upslope snow showers may linger over the northwest Alleghenies and Laurel Highlands. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Aside from some light upslope snow and weak lake-effect snow showers in the western mountains and northwest sector, the weekend will be quiet weather-wise. With the influence of high pressure overhead, the sun will make an appearance for the majority of the weekend. Daytime high temperatures will be about normal, but low temperatures on Saturday night will be quite chilly as clear skies will contribute to ample radiational cooling. Quiet weather doesn't last long, however. The next storm system is expected to bring precipitation to the Commonwealth on Monday morning. There is some model disagreement with precip types, but generally speaking, the system will start as snow for the majority of the Commonwealth and then transition into a mix/rain scenario for the southeast under the influence of warm advection as the system wraps up and moves out by Monday evening. Lingering lake-effect and upslope snow showers (with possibly a mix of ice as well) will hold on for the majority of Wednesday. && .AVIATION /04Z THURSDAY THROUGH MONDAY/... VFR conditions will deteriorate overnight as snow overspreads from SW to NE after midnight. Expecting visibility reductions to precede more gradual ceiling reductions with prevailing IFR areawide before daybreak. Heavier snow and LIFR visibilities will be possible across the southern tier during the morning hours on Thursday. Snow will weaken during the afternoon, but reductions will persist into the overnight hours. Outlook... Fri...Lingering snow showers north and east through midday. Improving conditions elsewhere. Sat...Mainly dry w/ VFR conditions. Sun...Prevailing VFR. Increasing clouds. Chance of snow west late. Mon...Widespread reductions in rain/snow. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 10 AM EST Friday for PAZ012- 017>019-024>028-033-034-037-041-042-045-046-049>053. Winter Storm Warning until 10 AM EST Friday for PAZ035-036- 056>059-063>066. && SYNOPSIS...DeVoir/Steinbugl NEAR TERM...Fitzgerald SHORT TERM...Fitzgerald LONG TERM...Gartner/Gutierrez/Wagner AVIATION...Banghoff
Hazardous Weather Outlook National Weather Service State College PA 239 PM EST Wed Feb 17 2021 PAZ035-036-056>059-063>066-181945- Fulton-Franklin-Perry-Dauphin-Schuylkill-Lebanon-Cumberland-Adams- York-Lancaster- 239 PM EST Wed Feb 17 2021 ...WINTER STORM WARNING IN EFFECT FROM 1 AM THURSDAY TO 10 AM EST FRIDAY... 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...Thursday through Tuesday. 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... Spotter activation is not expected at this time. PAZ012-017>019-024>028-033-034-037-041-042-045-046-049>053-181945- Northern Clinton-Clearfield-Northern Centre-Southern Centre-Cambria- Blair-Huntingdon-Mifflin-Juniata-Somerset-Bedford-Tioga- Northern Lycoming-Sullivan-Southern Clinton-Southern Lycoming-Union- Snyder-Montour-Northumberland-Columbia- 239 PM EST Wed Feb 17 2021 ...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM THURSDAY TO 10 AM EST FRIDAY... 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...Thursday through Tuesday. 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... Spotter activation is not expected at this time. PAZ004>006-010-011-181945- Warren-McKean-Potter-Elk-Cameron- 239 PM EST Wed Feb 17 2021 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...Thursday through Tuesday. The probability for widespread hazardous weather is low. .SPOTTER INFORMATION STATEMENT... Spotters are encouraged to report significant hazardous weather.
The national radar mosaic for the moment the first event began.
2 winter storm. Local standard time, as filed.
A winter storm produced 6 to 8 inches of snow across southern Lancaster County, most of which fell in an 11-hour period from 1am to 12pm on Thursday, February 18, 2021.
A winter storm produced 6 to 9 inches of snow across southern York County, most of which fell over an 11-hour period from 1am to 12pm on Thursday, February 18, 2021.
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, February 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: 941815, 941816.