Cool and Stormy: July 2009 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
August 3, 2009

You will not often see the title to a piece that delves into the weather of a New Jersey July reading "cool and stormy". But how else to describe a July that saw at least one locale in the state drop into the 40s on eight mornings and had nine days with National Weather Service Local Storm Reports filed? Read on for some details.

We will start with July temperatures, as they were the main story until the last week of the month and time and again had people talking about the near absence of summer heat. The preliminary July average temperature of 72.4° made this the 18th coolest since 1895 (see table below). We have benefited from several cool Julys this decade, as 2000 and 2001 were cooler than this year. However four of the warmest twelve Julys have also occurred this decade, including last year which at 76.7° ranked as the 9th hottest on record.

Rank Year July Avg Temp
1 1895 70.6°
2 1914 71.2°
3 2000 71.2°
4 1909 71.3°
5 1924 71.3°
6 1962 71.3°
7 1920 71.4°
8 2001 71.5°
9 1923 71.6°
10 1925 71.7°
11 1956 71.8°
12 1978 71.8°
13 1918 71.9°
14 1904 72.0°
15 1960 72.2°
16 1976 72.2°
17 1996 72.2°
18 2009 72.4°
19 1927 72.4°
20 1906 72.5°

Our late April heat wave, defined as a location experiencing 90° or higher maximums on three or more consecutive days, continues to be the only one of the year (dare I say "summer"?). Only five days in July saw one or more station equal or top the 90° mark, with a maximum of 91° for the month. Taking honors were Sicklerville (Camden County) and Eastampton (Burlington) at 91°. Three stations within the 50-station combined NJ Mesonet, NJ SafetyNet and RISE networks reached 90° on the 17th, seven on the 26th, eight on the 28th (Eastampton made it to 91°) and two on the 31st (Woodbine (Cape May) reached 91°).

During the relatively dry first three weeks of the month, lows bottomed out in the 40s on eight mornings. While most often the northwest valley station of Walpack (Sussex) led the way, with Pequest (Warren) never far behind, as many as a half dozen other stations joined in on four mornings. Walpack reached a statewide monthly low of 42° on the 14th, with a 43° reading the following morning. Basking Ridge (Somerset) at 49° was coolest on the 10th. Other mornings with lows between 45° and 48° included the 5th, 6th, 9th, 13th and 19th.

The cool July continued a pattern that began in late May. The combined June and July average temperature of 70.1° is the 15th coolest on record. Only 1992 and 1979 have been cooler dating back to 1928, with the others occurring between 1895 and 1927. June and July 2008 were the warmest combined early/mid-summer interval on record.

Late-month storms boosted the statewide precipitation total for the month to 4.96". This is 0.47" above normal and 43rd wettest. As is common in a summer month where thunderstorms deliver the bulk of our rainfall, totals varied widely across New Jersey. The three wettest locations were Califon (Hunterdon) with 9.28", Ramsey (Bergen) with 8.97" and High Bridge (Hunterdon) with 8.84". The driest locations included 2.09" at Bridgeton (Cumberland), 2.39" at Harvey Cedars (Ocean) and 2.59" at Woodbine (Cape May).

On fourteen July days more than an inch of rain fell in at least one location. Only four of these occurred during the first twenty days of the month (2nd, 8th, 12th, and 18th), while ten of the last twelve days were wet. A number of storms were accompanied by dangerous lightning, strong winds, hail, and flash flooding from excessive rain during a short interval. The heaviest event of the month impacted northern Hunterdon and western Morris counties early on the morning of the 2nd. One location in Califon (Hunterdon) was deluged with 4.37", while another location in that community approximately 2.5 miles away received 3.10" and nearby High Bridge (Hunterdon) saw 3.11".

A storm on the 7th brought 1.39" to River Vale (Bergen), tree and wire damage to Ramsey and Hillsdale, and quarter-inch diameter hail to the latter community. This was the first of six July days with hail reported somewhere in NJ. Another storm that day impacted Oceanport (Monmouth). Storms late on the 11th into the 12th brought 2.31" to Folsom (Atlantic) and 2.21" to Belmar (Monmouth). Trees were downed by a storm that passed through portions of Burlington and Camden counties on the 16th, along with half-inch diameter hail in Hamilton (Mercer). The next day saw similar damage from a storm traveling through Hunterdon, Somerset and Morris counties. Flemington (Hunterdon) received 1.13" during this event. Further north, Ramsey (Bergen) had some trees topple.

The active end of the month began with 2.45" and 2.09" falling on Buena Vista (Atlantic) and Franklin Township (Gloucester) on the morning of the 21st. Later in the day, 2.20" fell in Hawthorne (Passaic) and 2.01" in Lawrence Township (Mercer). The 23rd saw 1.94" fall in South Brunswick (Middlesex) and heavy rain fall elsewhere in central areas as well as up the coast. This interesting hybrid type storm (somewhere between a nor'easter and a tropical storm) brought a 41 mph wind gust to Harvey Cedars on Long Beach Island (Ocean). A thunderstorm brought wires down at several locations in Gloucester County on the 24th.

A supercell storm crossed New Jersey during the late afternoon of Sunday the 26th, carving a path that generally followed Route 78. A funnel cloud was sighted in Frenchtown, though apparently no tornado touched down. Winds gusted to 55 mph at Bedminster (Somerset), 42 in Pittstown (Hunterdon) and 40 in Kingwood (Hunterdon). Several tents were blown over at a balloon festival in Hunterdon, resulting in ten minor injuries. The storm continued east, resulting in further damage in Somerset, Union, Essex and Hudson counties. Four individuals were struck by lightning in a Newark (Essex) park, killing one member of the group. This storm was also a major hail producer, with quarter-inch to inch diameter hail in Hunterdon, Somerset, and Union counties. Another strong storm during the evening of the 26th brought 1.67" of rain to Hamilton Township (Mercer) and one quarter to three quarter inch hail along with some damage to locations in Burlington, Mercer, Middlesex and Monmouth counties.

Quarter-inch to inch diameter hail fell at several locations in Cape May County on the 27th. An afternoon storm on the 28th took the roof off of an apartment building in Andover (Sussex), with no reported injuries. Other locations in Sussex County experienced damage to trees and wires from this event and further east in Bergen County 1.56" fell in Ramsey. A late afternoon storm brought damaging winds to Middlesex County.

Numerous storms invaded the state on the 29th. The most serious one occurred in northern Sussex County, where an EF2 tornado with up to 120 mph winds destroyed several farm buildings and felled numerous trees in Wantage. Fortunately no injuries were reported in NJ, though several were injured near Stroudsburg, PA where it appears the storm cell first dropped a tornado. The National Weather Service has assembled information and an excellent map of the tornado path available here. Other storms on the 29th brought quarter-inch to inch diameter hail to locations in Somerset, Middlesex and Cumberland counties, and as much as 1.96" of rain to Westfield (Union). Damaging winds impacted Atlantic, Burlington, Camden, and Gloucester counties. A 58 mph gust was also reported in Bayonne (Hudson). Flash flooding was reported in Bergen, Passaic, Essex, Hudson and Union counties.

The last day of this volatile month brought small hail to Burlington County, along with a report of 3.25" of rain in 24 minutes in Pennsauken (Camden). If confirmed, this deluge will go down as a most notable one. Some 28 CoCoRaHS observers reported from 1-2" of rain, most of it falling in a short period of time. Flash flooding was observed in Burlington, Camden, Monmouth and Ocean counties, with wind damage in Camden, Burlington and Atlantic counties.

For those seeking more detailed information on hourly, daily and monthly conditions, please visit the following Office of the NJ State Climatologist's websites:

NJ Weather and Climate Network
NJ Community Collaborative Rain, Hail and Snow Network

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