Philadelphia torrent: City has rainiest day on record Sunday

From Hazel to Floyd to Sandy, the City of Brotherly Love has endured some great storms. Yet somehow, a rather modest mid-summer front managed to put down over 8 inches of rain in Philadelphia Sunday, giving the city its greatest daily deluge in over 140 years of weather records.

The 8.02 inches of rain that fell easily exceeded the previous single day record in Philadelphia of 6.63 inches from September 16, 1999 during hurricane Floyd.  The whopping total pushed its July rainfall over 13 inches, making it the wettest July on record by a healthy margin. The previous July record was the 10.42 inches that rained down in 1994.

Incredibly, 7.35 inches of the Sunday’s 8.02 inches fell in 4.5 hours (source @WxNick on Twitter) !

The rain can be blamed on a strong push of moist tropical air ahead of a slow-moving cold front (and a strong jet stream at high altitudes). In this humid, unstable air, strong thunderstorms developed in long, train-like formations, oriented from southwest to northeast. The storms then tracked over the same locations with unrelenting downpours.

Unlike a tropical storm, whose heavy rain often leaves a massive footprint, Sunday’s heavy rains were very localized, falling in a fairly narrow ribbon from Philadelphia into some of its eastern suburbs in southwest New Jersey.

“South Jersey, the southeastern half of Philadelphia, and down into Wilmington were the “winners” in the rainfall game as training set up shop and ran over the same real estate,” explains the blog PhiladephiaWeather.net.


Doppler radar estimated rainfall in the region around Philadelphia Sunday. Note: these amounts are likely underestimates in some locations. (National Weather Service)

Consider, also, Baltimore and Washington received just a trace of rain, and New York city logged less than a quarter inch.

The rain in Philadelphia and its eastern suburbs caused street flooding and, at Philadelphia International Airport, all American Airlines flights are cancelled through at least noon today due to power problems caused by the rain.

Here are a few images of the flooding, from Twitter:

Jason is currently the Washington Post’s weather editor. A native Washingtonian, Jason has been a weather enthusiast since age 10.
Comments
Show Comments
Most Read Local

Heat Tracker

48
90-degree days year-to-date
Yearly Average
36
Record Most
67 (1980,2010)
Record Fewest
7 (1886,1905)
Last Year
24

At a Glance

Fri.

thunderstorms
76° /90°
Drop 20%

Sat.

partlycloudyday
73° /84°

Sun.

partlycloudyday
69° /83°

Mon.

partlycloudyday
71° /89°

Tue.

thunderstorms
72° /90°
Drop 20%

Wed.

thunderstorms
73° /91°
National Airport
Dulles
BWI

Right Now

D.C. Area Almanac

 
National
Dulles
BWI
Avg. High
 
Avg. Low
 
Rec. High
 
Rec. Low
 
Sunrise
 
Sunset
°F
 
 
°C
Next Story
Jason Samenow · July 29, 2013

To keep reading, please enter your email address.

You’ll also receive from The Washington Post:
  • A free 6-week digital subscription
  • Our daily newsletter in your inbox

Please enter a valid email address

I have read and agree to the Terms of Service and Privacy Policy.

Please indicate agreement.

Thank you.

Check your inbox. We’ve sent an email explaining how to set up an account and activate your free digital subscription.