drought

Much like the entire fall season, the transition into the cold half of the year was in no great hurry in November. Leaves dropped from ten days to two weeks later than normal, but eventually by the 28th the temperature fell to the freezing mark at West Cape May (Cape May County) and Newark Airport (Essex), these being the last locations in the state to experience their first freeze. A major exception to the slowly-transitioning pattern was the moderate high-elevation snowfall the weekend before Thanksgiving.

Drought conditions continued to be worrisome across the state, even spreading southwards. However, back-to-back heavy rainfall events on the 29th and 30th provided some replenishment to thirsty soils and began adding water to surface reservoirs across central and northern counties. It will be interesting to see if the atmospheric pattern change that delivered the late-month soakings is fleeting or will be longer lasting. Monthly precipitation (rain and melted snow) averaged 2.48” across NJ. This is 1.13” below the 1981–2010 average and is the 43rd driest November since 1895. It is worth noting that most of the National Weather Service stations that go into determining this average report in the morning. Thus the rain that fell later on the 30th is not factored into the monthly average; rather, it will be part of the December total. Snowfall averaged 0.4” for NJ but broken into regions amounted to 1.3” in the north, 0.1” central, and 0” south. The statewide total is average for Novembers between 1981–2010 but 0.7” below the 1894–present average.

Summer warmth continued into September, only beginning to relinquish its grip on the Garden State during the last week of the month. The average statewide monthly temperature of 70.1° was 4.3° above the 1981–2010 mean. This ranks as the 4th warmest September going back to 1895, with five of the eight warmest Septembers occurring since 2005. Seven of the most recent 13 months have ranked in the top 10 for warmth in their respective months.

Monthly rainfall averaged 3.36” across the state, which is 0.69” below average and ranks as the 61st driest of the past 122 Septembers. However, as discussed below, the average this month does not show the wide disparity of rainfall between the northern and southern parts of the state. While concerns for persistent dry conditions continued increasing across most of NJ through mid September, two soakings in the south alleviated worries in this region. Meanwhile, only one event of note produced totals exceeding an inch in much of the north, thus this region remains much too dry. As of the 27th, a good deal of north and central NJ was considered in moderate drought, with the remainder deemed abnormally dry according to the US Drought Monitor. North Jersey remained under a NJ Department of Environmental Protection “drought watch."

The ninth month of 2015 served as a bookend of sorts to an extended warm season. The average statewide temperature of 70.7° was 4.5° above the 1981–2010 normal and ranks as the 3rd warmest on record (since 1895). This ranking is the same as that achieved in May, with the intervening months all above average, though not nearly as much so as these shoulder months. Five of the ten warmest Septembers have occurred since 2002. A look back at the past five months finds that this most recent May through September interval was the third warmest on record. Even more notable than the recent run of warm Septembers, eight of the top ten warm seasons occurred within the last 18 years and four within the last six years.

What had been a rather dry month with drought concerns ended on a damp note on the 30th with a wet episode that extended into early October. Through the 29th, the month ranked as the 14th driest. However, an approximate statewide-average rainfall of 1.50” on the 30th brought the monthly average to 3.44” (-0.63”) and with it the rank of 63rd driest.

This month had quite a variety of weather conditions around the state. This resulted in some areas experiencing flash flooding and others encroaching drought conditions. Damage resulted from the flooding and one storm even produced a nocturnal “heat burst.” Some minor brush fires and declining river, ground water, and reservoir levels accompanied subnormal rain totals. The dry conditions helped produce some wide daily swings from cool nighttime temperatures to consistently warm daytime maximums. Preliminary values show August 2015 to have a statewide average rainfall of 2.18”. This is 2.03” below normal and ranks as the 13th driest since statewide records commenced in 1895 (Table 1). The 74.5° average temperature was 1.1° above the 1981–2010 mean and ranks 21st warmest.

May 2015 was a warm and dry month across New Jersey. As the month ended, drought concerns were looming large, though rainfall in the north during the afternoon and evening of the 31st and continuing into the first days of June resulted in at least a temporary braking of the downward slide. Based on data gathered at long-term National Weather Service Cooperative Observing (COOP) stations, May rainfall averaged 1.08" across NJ. This is 2.92" below the 1981-2010 mean and ranks as the 3rd driest May since records commenced in 1895.

As those who have been reading these monthly narratives for some time now know, precipitation that falls at COOP stations after observation time on the last day of the month gets recorded as falling on the first day of the next month. Most COOP stations observe in the morning, thus the heavy showers that fell across north Jersey on the 31st were not factored into this May average, except for a few stations such as Newark Airport (which registered 3.83" on the 31st alone) that observe at midnight. The last time this situation had a notable impact on monthly rainfall was a daytime heavy rain event on April 30, 2014.