A storm system pulled a shield of preciptation over an arctic airmass that was in place over central Pennsylvania, producing a wintry mix of precipitation that quickly went over to freezing rain over the Laurel Highlands of Somerset and Cambria County. Ice accumulation in excess of a quarter of an inch was reported.
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The episode as NWS CTP wrote it up.
A storm system pulled a shield of preciptation over an arctic airmass that was in place over central Pennsylvania, producing a wintry mix of precipitation that quickly went over to freezing rain over the Laurel Highlands of Somerset and Cambria County. Ice accumulation in excess of a quarter of an inch was reported.
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 Dec 16, 6:08 PM EST, 52 minutes earlier.
Area Forecast Discussion National Weather Service State College PA 608 PM EST Fri Dec 16 2016 .SYNOPSIS... Low pressure tracking through the Great Lakes will bring wintry precipitation to central Pennsylvania. Snow will transition to a wintry mix tonight into Saturday and then to rain by Saturday afternoon as milder air works in. A cold front on Sunday will change rain back to snow, potentially resulting in a light accumulation. The associated shot of cold air will slowly moderate through next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Upgraded to Winter Storm Warning for Cambria and Somerset Counties given NCAR ensemble and hi res CAMs indicating increased potential for 0.25" or more of ice accretion from 06z tonight through 15z Saturday. Strong warming takes place after 15z which should change precip over to plain rain by 18z, but we expect warning criteria ice to occur over the Laurel Highlands before this happens. No other changes to going forecast this evening...all other headlines remain unchanged and timing and amounts look good. ...Previous discussion... Thicker clouds working in from the west this afternoon as next weather system takes aim on the region. The low pressure area will move toward the lower Great Lakes by early Saturday morning. A warm front extending east from the storm will move northward. Snow will break out over the NW around 03Z, and continue to overspread the remainder of the forecast area by morning. Cold air entrenched at the low levels will allow snow to be the main precip type into the wee hours of Saturday morning before a surge of warm air begins to move in aloft and creates a change-over to a wintry mix - starting late tonight over the south and spreading across the north by midday Sat. Best estimates range from a coating of snow over southern zones to as much as 4 inches over the NW. Most places will see one to two tenths of an inch of ice on top of that as the low level cold air is expected to hang tough through Saturday morning. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Models agree in making the warm front crawl north through the area Saturday, but the pattern gets complicated with the formation of a wave of low pressure on the front. The weak wave is made to squirt out to our southeast leaving relatively weak forcing in place, suggesting the steadiest precipitation will occur during the first half of the day, with more in the way of intermittent rain or showers for the afternoon. Hourly temps show below freezing temperatures retreating only slowly north through the morning into the afternoon leading to a prolonged period of light icing for much of the forecast area. Right now amounts are expected to remain in the advisory range but it will not take much of a QPF error to lead to higher amounts, esp over the south where window for icing is largest. Mild air continues to work into the region Sat night, with all areas going above freezing. Cold front with a fairly decent band of precip works into the western portion of CWA Sat night. This will initially fall as rain, but colder air working back in behind the front will likely change precip back over to snow at tail end, and could result in light accumulations. && .LONG TERM /SUNDAY THROUGH FRIDAY/... The storm system will finally move down the St Lawrence River Valley early Sunday, dragging a trailing cold front through the forecast area late Sunday morning into the afternoon. Colder air will move in behind the front creating the potential for a brief change back to snow before ending by Sunday evening. Right now post- frontal snow amounts look to be meager. Cold-dry weather will dominate much of the new work week before a new frontal system approaches for Thursday. GEFS/GFS and ECMWF have come to more in line with a deeper low moving across the Great Lakes and Lower Canada late Thursday int friday. If this occurs there is a chance for colder air to advect into the region Thursday night into Friday. However any snowfall looks to be mainly through the central mountains. && .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... VFR conditions under a thin but thickening mid/high deck and (finally!) surface winds of 10mph or less in SW flow ahead of an approaching weather system. Clouds will continue to thicken later today, as this weather system moves eastward. Snow (and restrictions) will move into the NW early this evening and spread across CWA tonight. As layer above the surface rapidly warms late tonight into Sat, precip will transition to a wintry mix of mainly sleet and freezing rain by 12z Saturday morning, with most places ending as plain rain Sat afternoon. IFR/MVFR will continue over the north and west, while VFR works into the Susq Valley and southern mtns on Sat with the changeover to rain. Though restrictions do spread back across the CWA Sat night. Icing could be a sig impact at lower flight levels late Fri night into first half of Sat as 850mb temps surge above freezing, but 925mb and surface temps struggle to warm above 0C. LLWS will also be a concern in strong SW flow at 850mb that reaches 40-50kts. Cold front pushes through Sunday as an area of rain likely ends as a quick period of wintry precip. Outside of the wintry precip areas, restrictions remain confined mainly to the NW terrain as flow again becomes breezy from the NW. Outlook... Fri night...Restrictions with light snow becoming likely. LLWS developing. Sat...MVFR/IFR. Wintry mix transitioning to rain from south to north. Increasing winds from the south with LLWS likely into Saturday night. Sun...MVFR/IFR. Rain early...ending as mix/snow. Mon-Wed...No sig wx. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 10 PM this evening to 4 PM EST Saturday for PAZ004>006-010>012-017>019-037-041-042-045-046- 049>053-058. Winter Storm Warning from 1 AM to 4 PM EST Saturday for PAZ024- 033. Winter Weather Advisory from 1 AM to 4 PM EST Saturday for PAZ025>028-034>036-056-057-059-063>066. && SYNOPSIS...RXR NEAR TERM...DeVoir/RXR SHORT TERM...RXR LONG TERM...La Corte/Ceru AVIATION...RXR
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE STATE COLLEGE PA 605 PM EST FRI DEC 16 2016 PAZ025>028-034>036-056-057-059-063>066-172315- BLAIR-HUNTINGDON-MIFFLIN-JUNIATA-BEDFORD-FULTON-FRANKLIN-PERRY- DAUPHIN-LEBANON-CUMBERLAND-ADAMS-YORK-LANCASTER- 605 PM EST FRI DEC 16 2016 ...WINTER WEATHER ADVISORY IN EFFECT FROM 1 AM TO 4 PM EST SATURDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...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...SATURDAY THROUGH THURSDAY. 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>012-017>019-037-041-042-045-046-049>053-058-172315- WARREN-MCKEAN-POTTER-ELK-CAMERON-NORTHERN CLINTON-CLEARFIELD- NORTHERN CENTRE-SOUTHERN CENTRE-TIOGA-NORTHERN LYCOMING-SULLIVAN- SOUTHERN CLINTON-SOUTHERN LYCOMING-UNION-SNYDER-MONTOUR- NORTHUMBERLAND-COLUMBIA-SCHUYLKILL- 605 PM EST FRI DEC 16 2016 ...WINTER WEATHER ADVISORY IN EFFECT FROM 10 PM THIS EVENING TO 4 PM EST SATURDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...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...SATURDAY THROUGH THURSDAY. 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. PAZ024-033-172315- CAMBRIA-SOMERSET- 605 PM EST FRI DEC 16 2016 ...WINTER STORM WARNING IN EFFECT FROM 1 AM TO 4 PM EST SATURDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...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...SATURDAY THROUGH THURSDAY. 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.
The national radar mosaic for the moment the first event began.
2 winter storm. Local standard time, as filed.
A wintry mix of precipitation produced 0.30-0.40 inches of ice accumulation across Somerset County.
A wintry mix of precipitation produced in excess of a quarter of an inch of ice accumulation in Cambria County.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2016Every state in 2016This day in weather historyWarnings in Pennsylvania, December 2016
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: 663085, 663086.