A low pressure system tracked east from the Plains states, spreading heavy snow over north-central Pennsylvania. The heavy snow started during the afternoon on the 20th and tapered off during the early morning on the 21st.
Every event with a place to put it; 11 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.
A low pressure system tracked east from the Plains states, spreading heavy snow over north-central Pennsylvania. The heavy snow started during the afternoon on the 20th and tapered off during the early morning on the 21st. Snowfall rates between 1-2 inches an hour were observed during the storm. Storm total snowfall ranged from 8 to 14 inches from Interstate 80 north to the New York line. The highest snowfall amounts were along and north of Route 6. A light wintry mix of snow, sleet and freezing rain occurred over central and southern sections of Pennsylvania.
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 20, 11:02 AM EST, 2 hours 58 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 1102 AM EST SUN FEB 20 2011 .SYNOPSIS... A LOW PRESSURE SYSTEM APPROACHING FROM THE MIDWEST WILL TRACK THROUGH CENTRAL PENNSYLVANIA TONIGHT AND EARLY MONDAY...BRINGING SEVERAL INCHES OF SNOW TO THE NORTH AND MIXED SNOW AND SLEET TO CENTRAL AREAS...ALONG WITH PATCHY FREEZING RAIN. ANOTHER SYSTEM WILL PASS JUST TO THE SOUTH OF PENNSYLVANIA MONDAY NIGHT...BRINGING A CHANCE FOR ADDITIONAL SIGNIFICANT WINTRY PRECIPITATION TO THE COMMONWEALTH. HIGH PRESSURE WILL BUILD ACROSS THE REGION TUESDAY WITH DRIER WEATHER HOLDING THROUGH MIDWEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HIGH CLOUDS INCREASING AS ANTICIPATED THIS MORNING ACROSS WESTERN AND CENTRAL PA. CHANGES TO VERY NEAR TERM ARE FEW. MODERATE SNOW EVENT UNFOLDING FOR NORTHERN PA TONIGHT AND WILL SERIOUSLY CONSIDER UPGRADING CURRENT ADVISORIES TO WINTER STORM WARNINGS FOR HEAVY SNOW NORTH OF I-80...AND PARTICULARLY ALONG AND NORTH OF STATE HIGHWAY 6 GIVEN OVERNIGHT SREFS AND GEFS RUNS. ADDITIONAL CHANGES MADE TO MONDAY NIGHT TIMEFRAME...WITH SHORTER RANGE GUIDANCE SUGGESTING POTENTIAL FOR LOCALLY HEAVY SNOWFALL FURTHER NORTH INTO CENTRAL PA MONDAY NIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... BASED ON 20/03 AND 20/09 SREFS...SIGNIFICANTLY BUMPED UP POPS FOR MONDAY NIGHT INTO TUESDAY INDICATING POTENTIAL FOR LIGHT TO MODERATE SNOW ACCUMS OVER ESPECIALLY CENTRAL PA. PREVIOUS DISCUSSION: EXPECTED SFC LOW TRACK ACROSS SOUTHERN PA WILL PLACE AXIS OF STRONGEST WAA/HEAVIEST PRECIP ACROSS NORTHERN PA TONIGHT. SREF MEAN QPF RANGES FROM NR 1 INCH ACROSS THE NW MTNS...TO ARND 0.25 INCHES ACROSS THE S TIER. MDL SOUNDINGS INDICATE AN INITIAL PERIOD OF SNOW EVERYWHERE. HOWEVER...WARM AIR STREAMING IN ALOFT WILL LIKELY RESULT IN A QUICK CHANGEOVER TO MIXED PRECIP...THEN PLAIN RAIN ACROSS SOUTHERN PA. POSITION OF ENSEMBLE MEAN 850MB 0C ISOTHERM SUGGESTS EVEN NORTHERN PA WILL SEE A CHANGEOVER BY 06Z. HOWEVER...ENOUGH LOW LVL COLD AIR SHOULD REMAIN LOCKED IN FROM ARND I-80 NORTH TO KEEP PRECIP IN THE FORM OF IP/FZRA. HAVE USED SREF PROBABILITY OF BLW FREEZING SFC TEMPS TO DELINEATE SOUTHERN BOUNDARY OF WINT WX ADVISORY. HAVE STUCK CLOSE TO WWD GRAPHIC IN TERMS OF SNOW/ICE ACCUMS. MOST PROBABLE SNOW ACCUMS RANGE FROM 1-3 INCHES ALONG I-80...TO 3-5 INCHES ALONG THE NY BORDER. ICE ACCUMS ALSO APPEAR LIKELY TO REMAIN BLW WARNING CRITERIA...GENERALLY BTWN ONE AND TWO TENTHS OF AN INCH ACROSS THE CENTRAL AND NORTHERN MTNS. LOW PRES WILL PASS EAST OF THE REGION BY MIDDAY MONDAY...CAUSING LINGERING PRECIP TO TAPER OFF. HOWEVER...SECOND WAVE OF LOW PRES IS FCST TO TRACK SOUTH OF PA MON NITE. GREATEST SNOW POTENTIAL WITH THIS SYSTEM WILL BE ACROSS THE HIGHER TERRAIN OF SOMERSET COUNTY. THERMAL PROFILES WILL INITIALLY BE MARGINAL FOR SNOW...ESP OVER THE LOWER TERRAIN OF SOUTHERN PA. HOWEVER...HIGHER TERRAIN OF SOMERSET COUNTY WILL FAVOR A FASTER CHANGE TO SNOW WITH THE POTENTIAL OF SEVERAL INCHES ACCUM. TEMPS MONDAY COULD REACH THE L50S ACROSS SOUTHERN PA. HOWEVER...NORTHERLY FLOW WILL ADVECT MUCH COLD AIR SOUTHWARD BY LATE IN THE DAY. && .LONG TERM /TUESDAY THROUGH SATURDAY/... HIGH CONFIDENCE OF DRY WEATHER LATER TUE/WED...AS ALL MODEL DATA TRACKING HIGH PRES ACROSS PA. NEXT WEATHER SYSTEM ARRIVES IN THE THURSDAY/FRIDAY TIME FRAME AND LOOKS TO BRING MILDER AIR WITH IT...SO PRECIPITATION LOOKS MORE LIKE RAIN AT THIS POINT. PROGRESSIVE PATTERN CONTINUES BEYOND WITH ANOTHER SYSTEM POSSIBLE NEXT WEEKEND. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... VFR CONDITIONS WITH JUST HIGH CLOUDS WILL BE THE RULE FOR MUCH OF TODAY AS SURFACE RIDGE SLIDES THROUGH. NW WINDS WILL DIMINISH UNDER 10 KTS TODAY AND SWING AROUND TO THE SOUTH/SE LATER IN THE DAY. DETERIORATING CONDITIONS AND WINTRY WEATHER ARRIVE LATE THIS AFTERNOON/EARLY EVENING AS LOW SLIDES OUR WAY VIA THE OHIO VALLEY. LIGHT SNOW AND MVFR CONDITIONS QUICKLY SPREAD FROM SW TO NE AROUND 00Z...WITH HEAVIER SNOW REDUCING VSBYS/CIGS FURTHER AT KBFD THROUGH 06Z. WARMER AIR SLIDES IN FROM THE SW...CHANGING SNOW TO A WINTRY MIX ELSEWHERE AS THE EVENING WEARS ON...AND IN JST EVENTUALLY TO PLAIN RAIN. SO ICING WILL BE A CONCERN FOR AVIATION. ALSO...LOW LEVEL WESTERLY JET WILL BE INCREASING LATE TONIGHT AS WELL...SO ADDED WIND SHEAR BACK INTO THE KJST-KAOO TAF. OUTLOOK... SUN NIGHT...MVFR TO IFR. SNOW NORTH...WINTRY MIX SOUTH. MON/TUE...IFR TO MVFR CIGS/VSBYS...WITH A FEW PERIODS OF SNOW/MIXED PRECIP/ OR RAIN POSSIBLE. WED-THU...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO NOON EST MONDAY FOR PAZ004>006-010>012-017>019-037-041-042-045-046- 049>053-058. && SYNOPSIS...FITZGERALD NEAR TERM...DEVOIR/FITZGERALD SHORT TERM...FITZGERALD LONG TERM...ROSS/FITZGERALD AVIATION...RXR
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE STATE COLLEGE PA 1104 AM EST SUN FEB 20 2011 PAZ004>006-010>012-017>019-037-041-042-045-046-049>053-058-211615- 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- 1104 AM EST SUN FEB 20 2011 ...WINTER WEATHER ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO NOON EST MONDAY... THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY 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...MONDAY THROUGH SATURDAY. 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>028-033>036-056-057-059-063>066-211615- CAMBRIA-BLAIR-HUNTINGDON-MIFFLIN-JUNIATA-SOMERSET-BEDFORD-FULTON- FRANKLIN-PERRY-DAUPHIN-LEBANON-CUMBERLAND-ADAMS-YORK-LANCASTER- 1104 AM EST SUN FEB 20 2011 THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL PENNSYLVANIA. .DAY ONE...TODAY AND TONIGHT. THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY. COLDER AIR WILL DROP SOUTHWARD ACROSS PENNSYLVANIA MONDAY AFTERNOON AND EVENING. RAIN OR MIXED PRECIPITATION WILL REDEVELOP ACROSS THE AREA MONDAY NIGHT AND CONTINUE INTO TUESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The national radar mosaic for the moment the first event began.
11 heavy snow. Local standard time, as filed.
Heavy snow accumulations between 6 and 10 inches were observed.
Heavy snow accumulations between 6 and 10 inches were observed.
Heavy snow accumulations between 10 and 14 inches were observed.
Heavy snow accumulations between 9 and 12 inches were observed.
Heavy snow accumulations between 6 and 8 inches were observed.
Heavy snow accumulations between 6 and 8 inches were observed.
Heavy snow accumulations between 6 and 8 inches were observed.
Heavy snow accumulations between 6 and 8 inches were observed.
Heavy snow accumulations between 6 and 8 inches were observed.
Heavy snow accumulations between 6 and 8 inches were observed.
Heavy snow accumulations between 8 and 10 inches were observed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Pennsylvania in 2011Every state in 2011This day in weather historyWarnings in Pennsylvania, February 2011
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: 274658, 274659, 274660, 274661, 274662, 274663, 274664, 274665, 274666, 274667, 274668.