A weakening cold front helped trigger scattered showers and thunderstorms with heavy rain during the evening of the 15th into the early morning of the 16th. Event precipitation totals during  multiple thunderstorms reached between 2.0 and 3.5 inches and caused flash flooding and flooding of smaller streams and creeks in southeastern Pennsylvania.  Hardest hit was the tri-county area of Delaware, Montgomery and Chester Counties where Doppler Radar storm total estimates and surface reports reached around 3.5 inches.

Flood in BUCKS, PENNSYLVANIA
From 15-MAY-12 20:33:00 to 15-MAY-12 20:50:00 (EST-5)
Location: KEELERSVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The runoff from thunderstorms with heavy rain between 630 p.m. EDT and 830 p.m. EDT on the 15th in Upper Bucks County caused minor flooding along the East Branch of the Perkiomen Creek later that evening.  The East Branch of the Perkiomen Creek near Dublin was above its 5 foot flood stage from 933 p.m. EDT through 950 p.m. EDT on the 15th. It crested at 5.09 feet at 945 p.m. EDT. Doppler Radar storm total estimates reached around 2 inches in a narrow band from Sellersville east through Pipersville.

Flash Flood in CHESTER, PENNSYLVANIA
From 15-MAY-12 23:52:00 to 16-MAY-12 01:30:00 (EST-5)
Location: COLONIAL VLG
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorms with heavy downpours caused flash flooding in extreme southeast Chester County overnight on the 15th with Tredyffrin and Easttown Townships hit the hardest. There were eight water rescues as flash flooding occurred along the headwaters of the Valley and Darby Creeks.  The Valley Creek at Valley Forge was above its 7 foot flood stage from 1252 a.m. EDT through 207 a.m. EDT on the 16th. It crested at 7.91 feet at 130 a.m. EDT.  Doppler Radar storm total estimates reached around 3.5 inches in those townships.

Flash Flood in MONTGOMERY, PENNSYLVANIA
From 15-MAY-12 23:41:00 to 16-MAY-12 01:30:00 (EST-5)
Location: ABRAMS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorms with heavy downpours caused flash flooding in extreme southwest Montgomery County overnight on the 15th centered around Upper Merion Township. In the township, flash flooding was reported along South Gulph Road as Gulph Creek flooded  Doppler Radar storm total estimates reached around 3.5 inches in the township. Actual event totals included 3.46 inches in Norristown and 2.07 inches in West Norriton.

Flash Flood in DELAWARE, PENNSYLVANIA
From 16-MAY-12 00:00:00 to 16-MAY-12 02:00:00 (EST-5)
Location: WYOLA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Thunderstorms with heavy downpours caused flash flooding in extreme northern Delaware County and included the headwaters of the Darby Creek as well as Crum Creek. Hardest hit were Radnor and Newtown Townships.  Doppler Radar storm total estimates reached around 3.5 inches in the northern part of those townships.  The Crum Creek near Newtown Square was above its 5 foot flood stage from 141 a.m. EDT through 543 a.m.. EDT on the 16th. It crested at 7.57 feet at 245 a.m. EDT.

Flash Flood in PHILADELPHIA, PENNSYLVANIA
From 16-MAY-12 01:25:00 to 16-MAY-12 01:55:00 (EST-5)
Location: CRESCENTVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Thunderstorms with heavy downpours caused flash flooding along the Frankford Creek in Philadelphia. Urban and poor drainage flooding occurred elsewhere in the city.  The Frankford Creek at Castor Avenue was above its 7 foot flood stage from 225 a.m. EDT through 255 a.m. EDT on the 16th. It crested at 7.9 feet at 245 a.m. EDT.   Doppler Radar storm total estimates reached around 2.5 inches in the northern part of the city. Actual event totals included 2.57 inches in Rockledge, 2.43 inches in Rhawnhurst and 2.26 inches at the Northeast Philadelphia Airport.

Flood in DELAWARE, PENNSYLVANIA
From 16-MAY-12 02:00:00 to 16-MAY-12 04:43:00 (EST-5)
Location: FLORIDA PARK
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Minor flooding along the Crum Creek continued into the early morning hours of the 16th. The Crum Creek near Newtown Square was above its 5 foot flood stage from 141 a.m. EDT through 543 a.m.. EDT on the 16th. It crested at 7.57 feet at 245 a.m. EDT.