A slow moving low pressure system and a deep southerly flow from the Gulf of Mexico and then the Atlantic Ocean dropped heavy rain across Delaware centered on the 30th. Event precipitation totals averaged 2 to 5 inches, with the highest amounts in New Castle County. This caused poor drainage and field flooding as well as flooding of creeks and rivers, mainly in New Castle County. Creek flooding in parts of New Castle County were the highest since Tropical Storm Irene in August of 2011. The steady rain began during the afternoon of the 29th and fell at its heaviest from the morning into the early evening of the 30th. The rain ended during the late evening of the 30th.

The heavy rain was caused by the combination of a strong high pressure system that built over the Canadian Maritimes that initiated the onshore flow and a strong, but slow moving low pressure system. The low pressure system was located in northwest Missouri on the morning of the 29th. It moved northeast to near Chicago during the afternoon of the 29th. The low pressure system then became nearly stationary in southern Wisconsin as its cold front reached Ohio early on the 30th. Then a new low pressure system developed on the frontal boundary and was over Eastern Tennessee on the morning of the 30th. The low pressure system reached West Virginia during the late afternoon on the 30th as its warm front started to move through Delmarva. The low pressure system reached north central Maryland at 11 p.m. EDT on the 30th as its warm front reached extreme southeast Pennsylvania and central New Jersey. The low pressure system reached the Allentown, Pennsylvania area at 5 a.m. EDT on May 1st and then was absorbed again into the frontal boundary associated with the original low as it moved into New York State that morning. The steady rain ended as the low pressure system passed north of Delaware.

Flood in NEW CASTLE, DELAWARE
From 30-APR-14 12:24:00 to 30-APR-14 23:59:00 (EST-5)
Location: CENTERVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Heavy rain caused considerable poor drainage and major river and creek flooding in New Castle County. Some of the crests were the highest since Tropical Storm Irene on August 28, 2011. Within Wilmington alone, five roadways were flooded and closed. The Christina River at Coochs Bridge had major flooding and was above its 10.5 foot flood stage from 124 p.m. EDT on the 30th through 332 a.m. EDT on May 1st. It crested at 12.67 feet at 1015 p.m. EDT on the 30th. This was historically the 6th highest crest on record for the river.  The White Clay Creek at Newark had minor flooding and was above its 11.5 foot flood stage from 744 p.m. EDT on the 30th through 334 a.m. EDT on May 1st. It crested at 13.71 feet at 1100 p.m. EDT on the 30th. Farther downstream, the White Clay Creek at Delaware Park had major flooding and was above its 13 foot flood stage from 413 p.m. EDT on the 30th through 802 a.m. EDT on May 1st. It crested at 16.90 feet at 100 a.m. EDT on May 1st. This was historically the 6th highest crest on record for the creek and the highest crest since August 28, 2011 associated with Tropical Storm Irene.  The Red Clay Creek at Wooddale had major flooding and was above its 7 foot flood stage from 417 p.m. EDT on the 30th through 403 a.m. EDT on the 1st. It crested at 11.41 feet at 1015 p.m. EDT on the 30th.  It was the 5th highest crest on record and the highest crest since Tropical Storm Irene on August 28, 2011.  Farther downstream, the Red Clay Creek at Stanton crested just below major flooding criteria. It was above its 15 foot flood stage from 407  p.m. EDT on the 30th through 627 a.m. EDT on the 1st. It crested at 19.97 feet at 1145 p.m. EDT on the 30th.  It was the 5th highest crest on record and also the highest crest since Tropical Storm Irene on August 28, 2011.  The Brandywine Creek at Wilmington had major flooding and was above its 16.5 foot flood stage from 1033 p.m. EDT on the 30th through 738 p.m. EDT on May 1st. It crested at 20.70 feet at 6 a.m. EDT on the 1st, a new record.  This new gage has been at this location since 2007. Higher relative crests could have occurred prior to that year.  Event precipitation totals included 5.15 inches in Prices Corner, 5.10 inches in Newark, 4.76 inches in Newport, 4.60 inches at the Wilmington Airport and 4.50 inches in Odessa.