May 2019: Severe Weather and Flooding Rain

After a few below normal severe weather seasons over the previous years, the last month of meteorological spring turned quite active for not only the traditional spots across the southern Plains, but also across the Ohio Valley through the Mid-Atlantic. The pattern that fell in place for this to occur also lent to an unusually wet month across many regions, with the exception of New England.

May 2019 began with departing high pressure, leaving behind a boundary that sparked a few storms which resulted in damaging wind across central Maryland on the 2nd. The next two weeks featured a cycle of sporadic heavy rain events across the Mid-Atlantic and backdoor fronts in New England. One low system became wrapped up along a front draped across Virginia, causing up to 1.00-1.50” of rain to fall on the 5th. And while Philadelphia into Virginia saw up to 5 to 10 degree above normal temperatures, NYC through Boston were stuck with slightly below average conditions with highs in the 50s and 60s.

The flip-flopping fronts gave the Northeast yet another soaker, with widespread 1-2” amounts on the 12th and 13th. A relatively tame week then followed, that is until the 19th when a severe outbreak occurred across eastern Pennsylvania. The blame would lie on a warm front that shifted east into New Jersey. Multiple wind damage reports were observed including up to one inch-sized hail. An EF-1 tornado also briefly touched down in Tinicum Township in Pennsylvania though this wouldn’t compare to the series of active days that were seen later in the month.

While outbreaks were ramping up in the middle of the country, the Mid-Atlantic also continued to slowly take a turn for the worse. Another set of storms on the 23rd dipped into southern Pennsylvania and Maryland, two of which rotated. One did produce an EF-1 in Columbia, MD which snapped trees and took part of an office roof off. After the storms, high pressure briefly worked in as a cold front pushed humid air out of the region. Memorial Day weekend was thus fairly pleasant, but the 26th in particular gave us a brief taste of summer as temperatures soared into the 80s and low 90s. While this heat on the 26th spawned a squall line for the Mid-Atlantic, Memorial Day itself ended up quite nice as the cold front cleared the region, with dry and seasonably warm weather for the day.

 

Following the holiday, the weather turned quite wild to say the least. On the 28th, a plethora of supercells developed across Pennsylvania and pushed into New Jersey. This created numerous reports of severe weather across the two states, including four tornadoes of the EF-0 and EF-1 variety in eastern PA. New Jersey also saw a brief EF-1 in Stanhope that unfortunately struck a high school. Falls, PA which had an EF-0 on the ground for three minutes resulted in one injury. This persistent westerly flow of unstable weather into the region, along with a wavering boundary would literally cause a repeat the next day on the 29th. Wind damage was reported from storms across PA, NJ, MD, and DE as well as several EF-0 and EF-1 tornadoes. Hail larger than golf balls was also observed in the Lehigh Valley!

The 30th was a bit more relaxed in terms of severe weather coverage, except for Maryland where two tornadoes touched down. Flooding, however, was more of the issue at this point across the rest of the Mid-Atlantic as a slug of heavy rain fell in the afternoon and evening. These torrential downpours dropped up to 2-4” inches of localized rainfall, generating areas of flash flooding and aggravated streams, especially across eastern PA and central NJ. We finished off the month just like the beginning with high pressure passing over and calming things down.

New England largely finished the month with near normal precipitation, but most other cities saw 2 to 4 inch surpluses. The repeated back door cold fronts also caused New York City and points north and west to see an average month with temperatures. However, anyone outside the influence of the fronts saw summer-like weather with some places up to 5 degrees above normal for the month. In fact, Baltimore, MD saw its 9th warmest May on record and Washington, D.C. likewise observed its 6th warmest on record!