drought

It is always comforting to enter the water demand season, namely summer, with a bit of a hydrological cushion. Such is the case this year across NJ, thanks to ample rain and some late-season snow in recent months. This timely precipitation has eliminated drought concerns that stemmed from drier-than-normal intervals during 2016. As a result of the precipitation deficits, ground water, streamflow, and reservoirs all dropped to precarious levels, thus the issuance last fall of a drought warning by the NJ Department of Environmental Protection over northern NJ and a drought watch in some southern counties. Aside from two reservoirs in west central NJ remaining below average, at the moment all other hydrological signs are positive. However, no one should let their guard down and fail to appreciate the finite nature of our fresh water resources, and how quickly a period of abundance can lapse again into drought.

More will be noted regarding spring (March–May) conditions later in this report. First taking a look at May, New Jersey experienced its 9th wettest on record, with observations extending back to 1895. The statewide average rainfall of 6.62” was 2.63” above the 1981–2010 average and the wettest May since 1990. Frequent clouds and rain resulted in many chilly days, however, a mid-month heat wave was impactful enough such that the average statewide temperature of 59.8° was only 0.7° below the 1981–2010 average. It was the 61st coolest May of the past 123 years, with none cooler since 2008.

On many an afternoon this past February, one had to be reminded that, according to the calendar, we were in the midst of a winter month. While there was a modest snowstorm for central and northern areas on the 9th, there were 11 days, including the day prior to the storm, when temperatures equaled or exceeded 60° at one or more New Jersey locations. The average statewide monthly temperature of 40.1° made February 2017 NJ’s mildest since records commenced in 1895. The average was 6.6° above the 1981–2010 mean and 1.0° above the previous record in 1998. In fact, the 2017 average was only 0.7° lower than the mean for March, and would rank as the 54th mildest (69th coolest) March on record. February precipitation (rain and melted snowfall) averaged 1.70”. This was 1.10” below the 30-year mean and ranks as the 11th driest on record. Only the storm on the 9th delivered more than an inch of rain or melted snow to some observing stations around the state.

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.