Isaias was the Big Story in August 2020

August started on quite an active note to say the least. The first few days were spent watching Hurricane Isaias near Florida before it made landfall in North Carolina and traversed into the Northeast. The month was not an overly hot one, but it felt so at times given the persistent high humidity. As is typical by late summer, severe weather began taking a backseat.

In the days leading up to landfall, Isaias grabbed everyone’s attention as it became clear it was taking a northerly trajectory into the Mid-Atlantic. As it moved into the Northeast, two very distinct areas developed between the western and eastern flanks of the storm, despite its downgrade to a tropical storm. Maryland, Pennsylvania, Delaware, and far western parts of NJ were caught in heavy rain and saw totals exceed 3”, with a swath of 5 to 8 inches in particular running from SE Maryland into the Lehigh Valley of PA. This caused extensive flash flooding and water rescues, along with several embedded tornadoes, including a rather destructive EF-2 across Philadelphia and Bucks County into Doylestown, PA.

Meanwhile, just east of the main track, rainfall dropped off rapidly toward the coast. In fact, many areas saw less than 2” to even just a few tenths of an inch, especially in Long Island and Connecticut on east. Unfortunately, this tradeoff meant strong winds. The Jersey shore saw wind gusts exceeding 70 mph, peaking at 109 mph along Long Beach Island. Further north, sustained winds over 40 mph brought down numerous trees and powerlines, suspending service on both the LIRR and Metro-North. Up to a third of customers in Connecticut lost power, and Westport, CT saw a waterspout move onshore, which actually was the first time a tornado associated with a tropical system ever touched down in the state.

Thankfully, the storm was picked up by an upper level system and quickly pushed out by the end of the day. In Isaias’s wake, warm yet humid weather persisted for much of the month. The front that helped move Isaias out, stalled for a time after its departure, resulting in storms across southeastern PA and northern DE. An EF-1 tornado actually touched down around Ashland, DE, causing a number of trees to come down. Later on around the 14th, a low spun off of the coast of Virginia and turned into Tropical Storm Kyle, but safely remained offshore away from the Northeast. Several ensuing fronts brought occasional thunderstorms, one of which managed to spin up an isolated tornado in Lincroft, NJ.

The most impactful severe event occurred on the 27th when a disturbance ran into a warm front in New England. A powerful line of storms descended from upstate New York into Massachusetts, Connecticut, and the Hudson Valley. Plenty of wind damage resulted along with several tornadoes between EF-0 and EF-1 strength: two in Connecticut and one in Montgomery, NY. After a rainy period shortly after, high pressure would bring fall-like weather to close out August as high temperatures dipped into the 70s.

Overall, the month was up to 2-2.5 degrees above normal, but there were no record-breakers except for Baltimore, MD who saw their 3rd warmest August on record. On the other hand, precipitation was extremely variable thanks to Isaias, as areas west of the I-95 corridor saw double to quadruple their usual rainfall. Unfortunately, with New England already running low for the season, it once again fell below normal, exacerbating a drought throughout the region that extended further south into Connecticut.