Winter Storm in Pennsylvania, January 20 to 21, 2001

Name: Winter Storm in Pennsylvania, January 20 to 21, 2001
Start: 2001-01-20T16:00
End: 2001-01-21T11:00
Location: Pennsylvania

January 20 to 21, 2001 · NWS PHI · 10 events in 10 counties and zones

Where it happened

Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 10

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.

What happened

The episode as NWS PHI wrote it up.

A vigorous upper air disturbance coupled with a low pressure system that was intensifying east of the New Jersey coast produced heavy snow across Eastern Pennsylvania. Precipitation started again as snow across most of Eastern Pennsylvania during the late afternoon and early evening of the 20th. In and around the local Philadelphia area, where the air mass was warmer, precipitation started as rain. During the evening precipitation then changed to sleet and then snow and by 10 p.m. EST it was snowing throughout Eastern Pennsylvania. The heaviest precipitation, thus the largest accumulation of snow fell in a band from Lancaster County northeastward through the Lehigh Valley. Accumulations ranged from three to twelve inches. The upper air disturbance was so strong that thunderstorms were reported in Delaware County and the Lehigh Valley. The snow ended shortly after daybreak on the 21st, except in the Poconos where it lingered throughout most of the morning.Because this event occurred on a Saturday night (the 20th) and a Sunday morning (the 21st), the number of traffic accidents was relatively lower. But, 30 people were injured around Noon EST on the 21st on Interstate 476 in Plymouth Meeting (Montgomery County) when a tour bus traveling from Scranton to Atlantic City attempted to pass a snow plow. While the passing the plow, the bus veered into the same lane as the plow, which struck the back of the bus and sent it into a sharp right turn into a drainage ditch. Two of the injuries were serious. A number of sporting events in the Poconos were cancelled for the evening of the 20th.Specific accumulations included 12 inches in Camelback Mountain (Monroe County) and Morgantown (Berks County), 10.8 inches in Williams Township (Northampton County), 8.3 inches in Reading (Berks County), 8.1 inches in Glenmoore (Chester County), 8 inches in Sellersville (Bucks County), Macungie (Lehigh County) and Saylorsburg (Monroe County), 7.6 inches in Boyertown (Berks County), 7.5 inches in Albrightsville (Carbon County), 7 inches in at the Lehigh Valley International Airport and Pottstown and Green Lane (Montgomery County), 6.5 inches in Downingtown (Chester County), 6.3 inches in East Stroudsburg (Monroe County), 6 inches in Fricks (Bucks County), 5.3 inches in Somerton (Philadelphia), 5 inches in Wynnewood (Montgomery County), 4.5 inches in Hamburg (Berks County), Jim Thorpe (Carbon County) and Valley Forge (Chester County), 4 inches in Clifton Heights and Crum Creek (Delaware County) and 3.6 inches at the Philadelphia International Airport.

What forecasters said that day

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 Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Jan 20, 3:29 PM EST, 31 minutes earlier.

Area forecast discussion, Jan 20, 3:29 PM EST, 31 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
329 PM EST SAT JAN 20 2001

THIS FCST HOLDS A FAIR AMOUNT OF CONTINUITY FROM PREVIOUS ONE. SOME
MINOR MODIFICATIONS TO SNOWFALL PREDICITIONS BASED ON COORD WITH
SURROUNDING OFFICES AND HPC AND A MILD DELAY IN PRECIPITATION
CHANGEOVER.

AVN AND ETA ARE IN GOOD AGREEMENT NOW ON THE PATH OF THE MID LEVEL
LOW...WHICH IS NOW GENERATING SNOW OVER THE CENTRAL OH RVR VALLEY.
THEY ARE ALSO IS FAIRLY GOOD AGREEMENT ON FAIRLY STRONG VERTICAL
VELOCITIES AS THIS FEATURE MOVES ACROSS FA. MOISTURE PLUME FROM THE
SSW HAS BEEN HANGING JUST OFF THE COAST ALL DAY BUT SOME OF THIS MAY
WELL GET SUCKED INTO THE APCHG SYSTEM. GVN MODELS HAVE A TENDENCY TO
UNDERPLAY SNOW DUE TO AN UPPER SYSTEM WAS FEELING GOOD ABOUT RAISING
SOME AMOUNTS OVER NRN AND CNTRL FA...BUT MODELS ALSO VERY CONSISTENT
IN DRYING US OUT FROM TIME TO TIME AOA H6 OVERNIGHT. THIS COULD
ACTUALLY MEAN OSCILLATING BETWEEN SN AND -FZDZ WHENEVER SNOW DEVELOPS...
BUT DIDNT FEEL CONFIDENT ENOUGH TO WORD FCST AS SUCH. JUST WENT
OCCASIONAL SNOW AND BASICALLY DID NOT INCREASE AMOUNTS.
IN FACT...DWN SRN AND ERN FA...THE TIMING OF A CHANGEOVER GETS
BACKED UP A LTL. DYNAMIC COOLG CERTAINLY WILL ENSURE THAT CHANGEOVER
EVERYWHERE...BUT THE DELAY S AND E MADE FOR SOME MODEST DECREASES IN
AMOUNTS THERE.

GUIDANCE TEMPS NOT TOO DIFFERENT FROM EACH OTHER OR FROM PREV FCST
AND BASICALLY ACCEPTED THEM. DID RADIATE US SOME TMRW NITE IN ALL
BUT FAR SRN AND SERN ZONES IN ANTICIPITATION OF LGT WINDS AND SNOW
COVER AS SFC HIGH MOVES IN. MAY NOT HAVE DONE IT ENOUGH. STAYED A
LTL UNDER GUIDANCE FOURTH PD...AGAIN IN ANTICIPATION OF SOME SNOW
COVER THAT DOESNT EXIST MOST LOCATIONS NOW.

ON THE MARINE...CONTINUE GALES FOR THE NJ/DE COASTS AND LWR DEL BAY
AND SCA FOR THE UPPER BAY. FEEL IT IS A MARGINAL GALE BUT DO NOT
FEEL IT IS PRUDENT TO DROP IT NOW.

.PHI...WINTER STORM WARNING PAZ054/055/060>062/067>071/NJZ001/007/
       008/009/010/012>020/026/MDZ008/DEZ001

       WINTER WEATHER ADVISORY MDZ012/015/019/020/DEZ002>004/
       NJZ021>025

       GALE WARNING COAST AND LOWER DE BAY.

       SCA UPPER DEL BAY.

MPD

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

10 winter storm. Local standard time, as filed.

Winter Storm, Bucks

When: January 20, 4:00 PM EST to January 21, 9:00 AM EST
Where: Bucks forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Winter Storm, Carbon

When: January 20, 4:00 PM EST to January 21, 10:00 AM EST
Where: Carbon forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.918, -75.709 (the zone’s center; the record gives no point)

Winter Storm, Montgomery

When: January 20, 4:00 PM EST to January 21, 8:00 AM EST
Where: Montgomery forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Winter Storm, Berks

When: January 20, 5:00 PM EST to January 21, 7:00 AM EST
Where: Berks forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.416, -75.926 (the zone’s center; the record gives no point)

Winter Storm, Chester

When: January 20, 5:00 PM EST to January 21, 7:00 AM EST
Where: Chester forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Winter Storm, Lehigh

When: January 20, 6:00 PM EST to January 21, 7:00 AM EST
Where: Lehigh forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.613, -75.592 (the zone’s center; the record gives no point)

Winter Storm, Northampton

When: January 20, 6:00 PM EST to January 21, 8:00 AM EST
Where: Northampton forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.754, -75.307 (the zone’s center; the record gives no point)

Winter Storm, Delaware

When: January 20, 7:00 PM EST to January 21, 7:00 AM EST
Where: Delaware forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 39.917, -75.399 (the zone’s center; the record gives no point)

Winter Storm, Monroe

When: January 20, 7:00 PM EST to January 21, 11:00 AM EST
Where: Monroe forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 41.058, -75.339 (the zone’s center; the record gives no point)

Winter Storm, Philadelphia

When: January 20, 7:00 PM EST to January 21, 8:00 AM EST
Where: Philadelphia forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.008, -75.134 (the zone’s center; the record gives no point)

What these are

Winter Storm: A storm that brought snow, sleet or freezing rain at warning levels, usually over several hours or days.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Pennsylvania in 2001 Every state in 2001 This day in weather history Warnings in Pennsylvania, January 2001

Sources

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: 5227851, 5227852, 5227932, 5227850, 5227928, 5227930, 5227933, 5227929, 5227931, 5227934.