Strong northwest winds behind a departing low pressure system produced wind gusts near 50 mph in Eastern Pennsylvania during the morning and afternoon of the 9th. In addition to downing weak trees, tree limbs and wires, the strong winds enhanced the spread of wildfires due to the recent dry weather and low relative humidity levels that day. In Philadelphia, the winds hampered firefighters battling a blaze at a four-story vacant warehouse at the intersection of East York and Jasper Streets that eventually collapsed and killed two firefighters and injured two others. The fire went to five alarms and embers started fires at four nearby residences and a building housing a furniture store at Kensington and East Boston Streets. Approximately thirty-one homes were evacuated as a precaution. A temporary shelter was established at a nearby elementary school. The American Red Cross assisted six displaced persons.
Peak wind gusts included 52 mph in Mount Pocono (Monroe County), 51 mph at the Northeast Philadelphia Airport and Kennett Square (Chester County), 48 mph in Allentown (Lehigh County) and Newbold (Bucks County), 47 mph in Reading (Berks County), 46 mph in Doylestown and 44 mph at the Philadelphia International Airport. The strong winds were caused by the pressure difference between a low pressure system moving northeast through the Saint Lawrence Valley and a high pressure system building into the Northern Plains. The pressure difference (gradient) became weaker that late afternoon as the strong winds ceased.

Strong Wind in PHILADELPHIA, PENNSYLVANIA
From 09-APR-12 09:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 44.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: ASOS

Strong Wind in MONROE, PENNSYLVANIA
From 09-APR-12 08:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 45.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: ASOS

Strong Wind in LEHIGH, PENNSYLVANIA
From 09-APR-12 08:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 42.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: ASOS

Strong Wind in CARBON, PENNSYLVANIA
From 09-APR-12 08:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 40.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Mesonet

Strong Wind in BERKS, PENNSYLVANIA
From 09-APR-12 08:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 41.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: ASOS

Strong Wind in NORTHAMPTON, PENNSYLVANIA
From 09-APR-12 08:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 42.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: ASOS

Strong Wind in CHESTER, PENNSYLVANIA
From 09-APR-12 09:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 44.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Mesonet

Strong Wind in BUCKS, PENNSYLVANIA
From 09-APR-12 09:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 40.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: WLON

Strong Wind in MONTGOMERY, PENNSYLVANIA
From 09-APR-12 09:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 40.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Mesonet

Strong Wind in DELAWARE, PENNSYLVANIA
From 09-APR-12 09:00:00 to 09-APR-12 17:00:00 (EST-5)
Magnitude: 40.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Mesonet