Here’s how much rain N.J. needs to help end the severe drought

There’s no question New Jersey needs a lot of rain to help make a dent in the severe drought conditions that are plaguing the state. But not too much rain at one time.
That’s the word from weather experts, who say it would be much better for our region to get some steady rain every week or so instead of a monster storm, like a Hurricane Irene or a Superstorm Sandy, with a brief period of torrential rain. Storms of that magnitude would bring widespread flash flooding and serious destruction, something that wouldn’t be welcome by anyone.
Each of New Jersey’s 21 counties currently has a rainfall deficit ranging from 9 inches to nearly 12 inches in the past three months, according to data from the National Weather Service.
However, the state doesn’t need that much rain in one week or one month to end the drought, according to New Jersey State Climatologist David Robinson.
Instead, Robinson believes the state needs several months of above-average precipitation — both rain and snow — to help replenish the streams, rivers, reservoirs and underground aquifers that have all been struggling from the long pattern of extremely dry weather.
Getting 9 to 12 inches of rain in a short period “would likely result in considerable runoff rather than water replenishing groundwater and ultimately, over months, keep rivers up and reservoirs filling,” said Robinson, whose office at Rutgers University oversees the Rutgers NJ Weather Network and provides input to the National Drought Mitigation Center.
Note: If you are unable to view this map on your device, click on this link.
Michael Silva, a meteorologist at the National Weather Service’s main forecast office in New Jersey, agrees the Garden State needs multiple rounds of moderate rain spread out over several months instead of one or two major storms that dump torrential rain in one day.
“Because it’s been so dry, the ground is very solid. A lot of the rain won’t soak into the ground,” Silva said.
“It’s gonna take a lot of little events over a long period of time to make a dent in the drought,” he added. “It could take several months to get out of it.”
But Silva said he welcomes the storm system that’s pushing its way into New Jersey Wednesday and Thursday, which is forecast to drop as much as 2 to 3 inches of rain in most of the northern half of the state and a half-inch to 1.5 inches of rain in the southern region — along with some light snow in high-terrain areas Thursday night.
“Every little bit helps,” Silva said. “But to get out of it (the drought), we’d have to get above-normal precipitation” for several months.
The map above shows the total rainfall deficit (how many inches below the normal rain) each county in New Jersey had from Aug. 20 through Nov. 17.
Most areas of New Jersey have had no substantial rain falling since August, and only a few light rain showers since late September.
The lack of rain has pushed most of the state into a severe drought and a wide swath of South Jersey into an extreme drought, which is even more serious than a severe drought and rare to occur in our state.
The drought continues to put a strain on drinking water sources, like reservoirs and underground aquifers. Some of the biggest reservoirs in New Jersey are at the lowest capacity seen in more than 20 years, and other reservoirs have dipped to their lowest levels on record.
This week’s rain “won’t erase the drought issues on its own without additional regular precipitation in the following weeks or months, but at least provides an opportunity to start clawing out from the deficits,” said Mat Gerbush, assistant state climatologist at Rutgers University.
“The hope is that this is the start of an overall wetter precipitation pattern to help gradually improve the situation, and there is some indication that more regular precipitation events may follow this one in the next few weeks,” Gerbush added. “But that remains to be seen.”
Nevertheless, Gerbush said he remains “cautiously optimistic for now.”
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Len Melisurgo may be reached at [email protected] or on X at @LensReality.