Dry Start but Wet End for September 2016

Posted: September 29, 2016, 11:32 am by sgraham


The U.S. Drought Monitor map as of September 27th, 2016.


The first half of September which marks the start of meteorological fall, continued the dry trend. For places like southern New Jersey and southeastern PA that held on to near average rainfall throughout the summer, the dry pattern placed the regions into the abnormally dry category (D0) on the US Drought Monitor. However, by the second half of the month, rain seemed to be in more abundance, especially for much of the mid-Atlantic which experienced a few notable flooding situations. The rainy pattern allowed North Jersey and Pennsylvania to finally pick-up enough rain to rise above average for the month but also led to two instances of minor to moderate coastal flooding that exacerbated freshwater flooding concerns. Unfortunately, the wet weather stayed south of the one area that truly is in dire needs of rain, New England. Its ongoing dangerous deficit only increased, keeping many in the US Drought Monitor's extreme drought (D3) classification. 

Although more rain makers hit the Northeast in September, severe weather diminished significantly with the handful of events occurring during the first half of the month. The first occurred in northern Virginia and the D.C. metro area on September 7th, resulting in straight-line damaging winds that knocked down plenty of tree limbs and power lines. Then, a nasty line of strong to severe thunderstorms ripped through extreme northern Connecticut and much of Massachusetts and New Hampshire on the 11th, with the highest wind gusts measured up to 67 mph! Finally, on September 14th, spotty locales across northern New Jersey, the Hudson Valley, and Long Island had their fair share of wind damage. The region had a close-call with Hermine as well around Labor Day weekend, which turned out to sea, luckily resulting in just some higher winds at the coasts, occasional showers, and rip current and low-end coastal flooding concerns.

A pre-frontal trough produced widespread damaging winds from extreme northern Connecticut up into southern Maine on September 11th.

A combination of rainfall and coastal flooding also plagued the mid-Atlantic in two separate incidents in September. The first occurred on the 19th, in which the Jersey Shore through the Delmarva experienced action stage coastal flooding, but a few inches of rain exacerbated conditions and flooded roads that normally do not during action stage tidal flooding. Then, a surge of tropical moisture combined with a slow moving disturbance from the 28th to 30th produced 3 - 6 inches of rain across Delaware and parts of South Jersey in just 24 to 36 hours! Additionally, persistent easterly winds on top of a New Moon during this time led to minor to even moderate coastal flooding. Meanwhile, New England barely received a drop of rain. As of September 30th, much of New England was still experiencing severe drought conditions, with areas of Massachusetts remaining in an extreme drought. The precipitation chart below the US Drought Monitor also helps illustrate the dividing line between below, near, and above average rainfall totals.

U.S. Drought Monitor as of September 27, 2016.

Monthly rainfall across the Northeast and mid-Atlantic region; extreme southeastern New Jersey through Virginia were slightly to well above average for the month.

Although the rainfall pattern was rather variable depending on location in September, the temperature trend was more uniform. While the first half of the month soared well above average with even a few 90 degree days matching daily record highs, the second half trended cooler. In fact, the transition to the fall season became very apparent during the final days of the month which ended near to even below normal! See the chart below to learn how Newark, NJ stacked up during the month.

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