September 2019: Active Start turns Dry & Quiet

By this time in 2018, the Northeast and Mid-Atlantic finally started to depart a stretch of unbearable heat and humidity. However, in September 2019, the region was on the opposite side of the spectrum, at least in terms of precipitation and active conditions. This year, September ended up on the warm side, but it sure was rather quiet for long stretches of time, giving us a break from severe weather. Well, sort of, at least after the initial few days. The first week of September saw two frontal passages that triggered squall lines and even a few tornadoes! The first was on the 2nd which brought healthy rainfall across New England (over an inch in Boston) and an EF-0 tornado late in the afternoon in Manorville, NY on Long Island. Fortunately, damage was limited to trees given the rural area the tornado touched down. A second tornado occurred on September 4th and trekked across Coventry, CT.  This tornado was stronger, clocking in as an EF-1 and produced some minor damage to buildings along with snapped and uprooted trees. Here are a few links about the Connecticut tornado on September 4th.

The rain that some locations saw from these two disturbances would not be matched for essentially the rest of the month as the pattern prevented any real moisture from sticking around. By the second week of September, most eyes were focused on Hurricane Dorian. After wreaking havoc across the Bahamas, the hurricane turned north and moved parallel to the southeast coast of the U.S. Dorian then accelerated northeast into the open Atlantic, but passed close enough to southern New England on September 6th to produce some gusty winds and rainfall. Here is a look at the waves that Dorian produced off of Long Island.

Successive high pressure systems then dominated the rest of the month with occasional, but brief interruptions from rain. Temperatures see-sawed as a result, but did favor the warmer side of trends. There was one push of true cool Canadian air by the third week that sent high temperatures into the 60s and 70s while at night it cooled well into the 40s and 50s, including some 30s across the interior Northeast! At the same time, not a single drop of rain had fallen. High pressure stayed anchored of the Northeast the entire time until September 23rd when it began to shift offshore. A return flow then developed out of the southwest for the remainder of the month, which pushed temperatures back into the 80s and 90s across the region. Temperatures generally ended up 10 to 20 degrees above normal, marking the warmest part of September. Other than the first week of the month, September was basically a quiet one overall, without too much fanfare. Temperatures finished 3 to 6 degrees above normal across the board. In fact, it was the warmest September on record in Baltimore, MD breaking the old mark set in 1970. Lack of precipitation was the bigger story as the region barely received tropical moisture that usually falls at this time of year. In fact, New York City and Philadelphia both saw their top 10 driest months, while Baltimore had its driest on record since 1967 only receiving 0.16" of rain!