A Stormy August 2019

While August is usually a step down from the severe weather, it certainly ended up more active than normal. Just to give an example, by the 22nd, we had already seen 16 days of severe weather which is abnormal even for that time of year. And the heat continued as expected but thankfully the humidity was not as high as last year’s swelter. Let’s see how the last month of meteorological summer panned out.

A boundary lingered just off the coast to start the month, but high pressure dominated the Northeast for the first few days of August. Temperatures were generally up to 5 degrees above normal for the period, which put much of the region into the 80s. As a cold front approached, humid air surged back into the region by the middle of the week providing the Mid-Atlantic and Northeast with a vigorous severe weather day on the 7th. Numerous storms resulted in wind damage across every state as well as three tornadoes (all EF-0’s) across New Jersey (which has had an abnormally high number of tornadoes this summer). The heavy rain also totaled over an inch across most of the I-95 cities as well.

The following week’s pattern waffled between high pressure and the occasional stalled front. By the middle of the month, the upper level pattern allowed for a sultry air mass to take over which sent temperatures as much as 10 degrees above normal, into the 80s and 90s. These conditions were ripe for violent storm days, particularly on the 18th and 22nd. On the 18th, several storms produced quarter-inch sized hail in eastern Pennsylvania and New Jersey. The 22nd was more localized with t-storm activity however, one storm in particular trekked across northern NJ through Long Island, which caused extensive damage. Numerous trees were uprooted and some buildings even partially destroyed. There were also a multitude of power outages that lasted into the next day.

             Incoming storm on August 18th in NYC from meteorologist Matt Wunsch.

Sweet relief came on the 23rd when a cold front brought the first true “cool” Canadian air mass since spring. Temperatures crashed into the 70s, giving the Northeast quarter of the U.S. tastes of fall when some inland locations fell into the 40s at night! This kind of air mass also kept the weather rather quiet, but the 28th was the exception as a cold front and tropical disturbance offshore interacted with each other. While Tropical Depression Erin remained off the coast, a plume of tropical moisture triggered heavy rainfall across eastern New England (up to 1.5-3” of rain). Quiet weather then rounded out the month.

At this point, the keen observer is likely noting how quickly the days are diminishing now that we are well past the peak of summer. And indeed, cold fronts themselves are beginning to successfully push in cooler air now that subtle but noticeable changes are taking place as we enter autumn. The brief warm-up did push the month above normal, but not by much (0.5-2 degrees on average). Baltimore, MD did see its 9th warmest August on record, but most other places were nowhere near record-breaking. A few days between the 19th and 22nd did peak in the mid-upper 90s, with Baltimore, MD and Washington, D.C. hitting 98 and 99 degrees, respectively. Precipitation was more or less average even with Erin’s moisture late in the month.