A slow moving low pressure system at both the surface and aloft helped trigger very heavy rain across Montgomery County from the late morning into the afternoon 20th. Storm totals averaged between 1.5 and 3.5 inches, most of which fell during the afternoon at the rate of half an inch per hour. The heavy rain led to widespread poor drainage flooding as well as flooding along some of the gaged rivers and streams in the county. Several vehicles became stuck in flood waters. The worst flooding occurred along the Perkiomen Basin in the upper half of the county. The West Branch of the Perkiomen Creek at East Greenville was above its 4 foot flood stage from 848 p.m. EDT on the 20th through 430 a.m. EDT on the 21st. It crested at 6.5 feet at 1215 a.m. EDT on the 21st. A bit farther downstream, in Hillegass, the creek was above its 5 foot flood stage from 754 p.m. EDT on the 20th through 215 a.m. EDT on the 21st. It crested at 5.32 feet at 930 p.m. EDT on the 20th. The East Branch of the Perkiomen Creek in Schwenksville was above its 7 foot flood stage from 710 p.m. EDT on the 20th through 334 a.m. EDT on the 21st. It crested at 8.28 feet at 1130 p.m. EDT on the 20th. Along the main stem of the Perkiomen Creek at Graterford, the creek was above its 11 foot flood stage from 824 p.m. EDT on the 20th through 740 a.m. EDT on the 21st. It crested at 13.78 feet at 130 a.m. EDT on the 21st. The first gaged creek to go over in the county was the Manatawny Creek in Pottstown which reached its 6 foot flood stage at 550 p.m. EDT on the 20th, crested at 9.55 feet 830 p.m. EDT on the 20th and was back within bankfull at 924 a.m. EDT on the 21st. The Schuylkill River in Pottstown was briefly above its 13 foot flood stage from 1022 p.m EDT through 1140 p.m. EDT on the 20th. It crested at 13.04 feet at 11 p.m. EDT.  Storm totals included 3.89 inches in Pottstown, 3.35 inches in Wynnewood, 3.18 inches in Palm, 2.80 inches in Green Lane, 2.30 inches in Royersford and 1.51 inches at the Willow Grove NAS. The low pressure system responsible for the heavy rain formed along a stationary front over the Carolinas during the morning of the 20th. It moved to just east of Wallops Island, Virginia during the evening of the 20th and well east of the Delmarva Peninsula during the morning of the 21st. An inverted trough at the surface that extended from the low north into Chesapeake Bay and Eastern Pennsylvania concentrated the heavy rain along its axis. June as a whole was an unseasonably wet month. On a county weighted average, June monthly precipitation totals averaged 9.5 inches in Montgomery County. Normal is around 3.5 inches. The June monthly precipitation total of 8.08 inches at the Philadelphia International Airport was the second wettest on record. The wet spring weather led to a whole different set of problems from the drought of the previous year. Planted seeds were drowning and rotting. Many soybean, corn and berry fields were too wet. There were also problems with slugs. Vegetables were generally about a month behind. Double crop fields fell behind schedule because of the slow growth of straw and hay. Garden shops sales have been down. Pool installations were about three to six weeks behind. Ant infestations increased. Windshield wipers were tearing. Many spring athletic seasons were extended because of postponed events. There will be a bumper crop of mosquitoes. Attendance along the shore and at amusement parks was down. Road work was delayed. The one few positives from the wet weather was lower utility bills.

Flood in MONTGOMERY, PENNSYLVANIA
From 20-JUN-03 16:50:00 to 21-JUN-03 08:24:00 (EST)
Reported by: AWOS,ASOS,MESONET,ETC