A series of thunderstorms that moved through eastern Berks, northern Montgomery, southern Lehigh, western Northampton and Monroe Counties caused poor drainage flooding as well as flash flooding in Northampton and Monroe Counties during the evening of the 28th. Along the heaviest band, event precipitation totals averaged 2 to 4 inches. Runoff from the heavy rain then caused some creek flooding that persisted into the 29th in Montgomery and Northampton Counties. The thunderstorms also caused lightning damage to a home in Northampton County.  The heavy rain culminated the wettest September for the state of Pennsylvania dating back to 1895. The 9.71 inch statewide average for the month was more than twice the normal value. It was also the wettest September on record in Allentown (12.99 inches) and the third wettest September on record in Philadelphia (10.27 inches).

Flash Flood in NORTHAMPTON, PENNSYLVANIA
From 28-SEP-11 19:00:00 to 28-SEP-11 21:00:00 (EST-5)
Location: BATH
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorms with heavy rain caused flash flooding from Bath through Bethlehem in the Monocacy Creek drainage basin. In Bath, water rescues and voluntary evacuations occurred. The Monocacy Creek flooded businesses and a senior high rise building. Flooding was also reported into the first floor of a few homes. Flooding was reported on Main, Chestnut and Northampton Streets. Downstream in East Allen Township, basement flooding up to twelve feet was reported.  In Bethlehem, the Monocacy Creek at Illicks Mill Road was above its 4.5 foot flood stage from 820 p.m. EDT through 950 p.m. EDT on the 28th. It crested at 4.94 feet at 915 p.m. EDT.  Event precipitation totals included 3.24 inches at the Lehigh Valley International Airport, 2.56 inches in Martins Creek and 1.74 inches in Bethlehem.

Flash Flood in MONROE, PENNSYLVANIA
From 28-SEP-11 19:00:00 to 28-SEP-11 21:00:00 (EST-5)
Location: MC MICHAELS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorms with heavy rain caused poor drainage and small creek flash flooding in south central Monroe County, mainly in Ross and Chestnuthill Townships. Adjusted Doppler Radar storm total estimates averaged 3 to 4 inches in the townships. Event precipitation totals included 3.84 inches in Hamilton Township and 2.71 inches in Blakeslee.

Flood in MONTGOMERY, PENNSYLVANIA
From 28-SEP-11 17:31:00 to 29-SEP-11 00:50:00 (EST-5)
Location: RED HILL
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

For the third time this month, runoff from heavy rain that fell on the 28th caused minor flooding in the headwaters of the Perkiomen Creek around the Green Lane Reservoir. The Main Stem of the Perkiomen Creek at East Greenville was above its 4.0 foot flood stage from 903 p.m. EDT on the 28th through 150 a.m. EDT on the 29th. It crested at 5.0 feet at 1145 p.m. EDT on the 28th.  The West Branch of the Perkiomen Creek at Hillegass was above its 5.0 foot flood stage from 631 p.m. EDT through 1006 p.m. EDT on the 28th. It crested at 5.31 feet at 830 p.m. EDT on the 28th.  Event precipitation totals included 3.53 inches in Pottstown, 2.43 inches in Gilbertsville and 1.71 inches in Green Lane.

Lightning in NORTHAMPTON, PENNSYLVANIA
From 29-SEP-11 00:45:00 to 29-SEP-11 00:45:00 (EST-5)
Location: STEUBEN
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Newspaper

A lightning strike and ensuing fire damaged a home on Stafford Avenue in Lower Nazareth Township. It took firefighters about three hours to totally extinguish the blaze.

Flash Flood in LEHIGH, PENNSYLVANIA
From 28-SEP-11 19:00:00 to 28-SEP-11 21:00:00 (EST-5)
Location: WEST CATASAUQUA
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Newspaper

Thunderstorms with heavy rain caused flash flooding along the Catasauqua Creek. Several businesses along the creek were flooded and suffered damage. Event precipitation totals included 3.24 inches at the Lehigh Valley International Airport and 2.91 inches within Allentown.

Flood in NORTHAMPTON, PENNSYLVANIA
From 29-SEP-11 00:47:00 to 29-SEP-11 17:00:00 (EST-5)
Location: WESTGATE HILLS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Runoff from heavy rain that fell on the 28th caused major flooding along the Monocacy Creek in Bethlehem. It was the highest crest for the creek since the remnants of Hurricane Ivan in September of 2004. Once again the Industrial Colonial Quarter in Bethlehem was flooded. The Monocacy Creek in Bethlehem at Illicks Mill Road was above its 4.5 foot flood stage from 147 a.m. EDT through 6 p.m. EDT on the 29th. It crested at 7.66 feet at 515 a.m. EDT.