Sneaky Warmth and Awfully Wet
April 2011 Overview

Dr. David A. Robinson
New Jersey State Climatologist
Center for Environmental Prediction, School of Environmental and Biological Sciences/NJAES, Rutgers University
May 6, 2011

While clouds that produced ample rain made it seem to most of us that this past month averaged on the cool side of the ledger, in actuality New Jersey experienced its 7th warmest April since statewide records commenced in 1895 (see table below). The mean temperature of 53.8° was 3.3° above average. Perhaps the sense of a cool April was due to this year being cooler than last year's record warmth. Or might we just be getting used to April "heat", as five of the twelve warmest Aprils have occurred in the past ten years?

Rank Year April Temp.
1 2010 55.8°
2 1921 55.6°
3 1941 54.9°
4 2002 54.6°
5 1960 54.2°
6 1945 54.1°
7 2011 53.8°
7 1994 53.8°
9 1915 53.7°
10 2006 53.6°
11 1976 53.3°
11 2008 53.3°
13 1985 53.2°
14 1998 53.1°
15 1981 53.0°

On six April afternoons, temperatures topped the 80° mark somewhere in New Jersey. The 11th saw Howell (Monmouth County) top out at 88° (state maximum for the month), Holmdel (Monmouth) reached 87° and Eastampton (Burlington) was 86°. Meanwhile, a sea breeze kept the maximum to 57° at Harvey Cedars (Ocean) and at the Atlantic City Marina (Atlantic). Warmth returned on the 20th with four southern Jersey stations reaching 84°. Statewide, the warmest April day was the 24th, with Toms River reaching 87° and three other stations at 86°. The temperature even rose to 67° at High Point Monument (Sussex) and 69° at West Cape May, the cool spots in the state. The 26th found Sicklerville (Camden) at 85° and eleven other stations at 84°. Sicklerville reached 83° and four stations 82° on the 27th. Hammonton hit 82° on the 28th with Piney Hollow (Gloucester) and New Brunswick (Middlesex) at 80°.

Despite the above average temperatures in April there were twelve mornings when one or more locations fell below the freezing mark. The High Point and High Point Monument stations dipped to 29° on the 1st, with three stations at 31°. Walpack (Sussex) was 25° on the 2nd and Pequest (Warren) 27°. This last location fell to the same mark on the 3rd, with Walpack and Hope (Warren) at 28°. The 5th-9th saw lows ranging from 27° to 30° at stations including High Point Monument, Berkeley Township (Ocean), Walpack and Pequest. The two High Point stations reached 31° on the 16th and Walpack 29° on the 18th. Walpack and High Point were at 31° by late evening on the 21st. Numerous other stations fell below freezing by dawn on the 22nd, which proved to be the coldest April morning. Walpack dropped to 21° and Pequest to 26°. Stations in ten of the 21 counties fell below freezing, with the warmest location being West Cape May (Cape May) at 43°.

April showers were plentiful and brought renewed flooding to the Garden State on the heels of the major flooding last month. On average, 5.67" fell across the state. This is 1.74" above normal and ranks as the 13th wettest on record. There was a rather wide disparity in monthly totals, with the north central region wettest and far south driest. West Milford (Passaic) topped all totals with 9.49". This was followed by 8.93" in Mendham (Morris), 8.73" at Randolph (Morris), 8.62" in Oakland (Bergen) and 8.48" at Rockaway (Morris). Dennis Township (Cape May) at 3.34" had the least precipitation, while the next lowest were 3.37" in Middle Township (Cape May), 3.60" in Lower Township (Cape May), 3.82" in Lavallette (Ocean), and 4.07" in Lacey Township (Ocean).

While wet conditions over the course of the month slowed the progress of outdoors work, including in the agricultural sector. However overall the news was good on the water resources front, as river discharges are above average, ground water levels are decent and reservoirs are full.

Rank Year April Prcp
1 2007 9.07"
2 1983 8.91"
3 1973 6.64"
4 1952 6.58"
5 1980 6.28"
6 1929 6.22"
7 1901 6.18"
8 1964 5.99"
9 1924 5.95"
10 1909 5.77"
11 1982 5.72"
11 1958 5.72"
13 2011 5.67"
14 1913 5.59"
15 1940 5.57"

The 1st brought the only measureable snow of the month. High Point took top honors with 4.7" of the white stuff, while accumulations elsewhere included Liberty Township (Warren) 3.0", Holland Township (Hunterdon) 2.0" and Greenwich Township (Warren) 1.4". Much of northern and central NJ saw flakes flying and briefly accumulating that morning. The south received the heaviest precipitation from this event, with 0.69" in Lacey Township (Ocean) and Stafford and Little Egg Harbor townships in Ocean County both catching 0.61". The northwest corner of the state saw a few flakes fall and up to 0.62" of rain accumulate at Walpack (Sussex) on the 5th, with High Point receiving 0.57". Thunder was heard in some locations. A trace of snow also fell at a few locations on the 6th-7th when a statewide event brought as much as 0.41" to Sparta (Sussex) and 0.39" to Washington (Warren). Central and southern areas were wettest on the 8th, with 0.82" falling at Little Egg Harbor Township and 0.81" and 0.78" at stations in Medford (Burlington).

Local showers brought 0.42" to Bernards Township and 0.38" to Peapack-Gladstone in northern Somerset County on the 11th. A more formidable event, replete with thunder and lightning brought heavy rain in a swath from central to northeast NJ on the 12th-13th. 1.85" accumulated in Mendham (Morris), 1.78" in River Vale (Bergen), and 1.72" in Bridgewater (Somerset). This rain primed the surface for flooding to occur quite rapidly when heavy thunderstorm rains fell throughout much of NJ from mid day on the 16th to early on the 17th. As was the case in March, the heaviest rain fell in the Highlands, with 4.25" and 3.87" at stations in West Milford (Passaic), 3.85" in Ringwood (Passaic) and 3.77" at Little Falls (Passaic). The remainder of the north, along with central and the bulk of southern NJ received more than 1.50". Only coastal areas remained in the 0.75"-1.50" range. The result of these rains was the most impactful event of April. While most rivers in the Passaic basin crested several feet below March 2011 levels, flooding was still moderate to borderline major. Road closures and the evacuation of fewer than 100 homes resulted. Flood crests in the Raritan basin were a few feet higher than in March but overall were considered moderate. Road closures were plentiful but there were not any major impacts.

The 22nd-23rd saw a moderate event begin with a few flakes of snow or sleet pellets in some locations. The most rain fell in the north, with 1.02" in Ewing Township (Mercer) and 0.99" at Demarest (Bergen). Southern areas had a few tenths of an inch of rain. Easter evening (24th) brought two bands of moderate thunderstorms crossing from southwest to northeast across central and southern NJ. Top rainfall honors went to two stations in Reading Township (Hunterdon) with 1.44" and 1.36", with Long Hill Township (Morris) catching 1.02". Localized thunderstorms brought rain mostly to Morris County on the 27th, with 0.59" in Mendham and Denville. Heavier bands of thunderstorms dropped 0.75" to 1.00" at many locations from Warren to Bergen counties and in Cape May County on the 28th. The most rain fell at Randolph Township (reports of 1.63" and 1.36"), Holland Township (Hunterdon; 1.39"), and Washington (Warren; 1.27"). Totals elsewhere in the state were within a few tenths of 0.50". This event brought damaging straight line winds to portions of Morris County around mid day. Trees were toppled by straight line winds onto homes, fences and wires. These storms were the remnants of the system that brought the tragic outburst of tornadoes to the southeast US the previous day.

The most interesting precipitation gauge report of the month came from a CoCoRaHS observer from Cumberland County. On the 11th he reported an accumulation of 0.1" of beetles!

Among other reports of notable weather during April, heavy fog impacted travel on the 20th and was particularly widespread on the morning of the 26th. The lowest barometric pressures were observed on the 5th at about 29.20" to 29.25" of mercury. The cold high pressure system on the 22nd saw the barometer rise to 30.50" to 30.55". On ten April days wind gusts equaled or exceeded 40 mph at one or more NJ observing sites. On the 4th a 52 mph gust occurred at the Atlantic City Marina (Atlantic) and 40 mph at Harvey Cedars (Ocean). The strongest gust of the month of 63 mph was observed at Wantage (Sussex) on the 5th, when the Atlantic City Marina reached 52 mph. Red Lion (Burlington) reached 40 mph on the 6th and Wantage 41 mph on the 11th. Seaside Heights (Ocean) saw a gust to 48 mph on the 12th, with three other stations reaching 43 mph. Sea Girt (Monmouth) reached 45 mph on the 13th and Seaside Heights 43 mph. The 16th brought gusts of 59 mph to Bivalve (Cumberland) and 47 mph to Harvey Cedars. Hillsborough (Somerset) topped out at 48 mph on the 17th, Wantage at 54 mph on the 21st, and gusts of 49 mph and 42 mph were recorded at Atlantic City Mariana and Seaside Heights on the 28th.

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
NJ Snow Event Reports

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