8 Things to Know about New Jersey’s Impending Heavy Rain
The remnants of former Hurricane Patricia will bring the potential for heavy rain and flooding to New Jersey over the next few days.
1.) The Bottom Line
The remnants of once-Hurricane Patricia will travel up the U.S. East Coast over the next few days. While this storm system has weakened considerably since it exploded in the Pacific Ocean, it will probably deliver New Jersey's biggest rainfall totals in several weeks. With the chance of heavy rain will also come the chance for flooding (flash, river, and coastal) and some gusty winds.
Again, just so I am crystal clear, this impending storm system is comprised of the remnant moisture and energy of Patricia. It is no longer anything close to or resembling a hurricane. Keep reading for more...
The meteorology world was buzzing late last week as Patricia exploded in the warm waters of the northeastern Pacific Ocean, becoming the strongest hurricane ever recorded in the Western Hemisphere. While at one point the storm packed 200+ mph sustained winds and a minimum central pressure of 879 mb, Patricia rapidly fell apart over the mountainous interior of Mexico. As the extra-tropical storm continued tracking toward the north and east, parts of the U.S. Gulf Coast were drenched by 9+ inches of rain, spurring flash flooding (in addition to some surge along the coast). A few reports of thunderstorm wind and tornado damage were reported in Louisiana.
It is becoming increasingly likely there will be a period of "washout" for New Jersey in the coming days. Unfortunately, there are still some minor differences and question marks among the forecast models' exact timing of the rain. Here are three possible scenarios...
The NAM model says the raindrops will begin to fall in South Jersey Tuesday evening, spreading to the entire state through the early morning hours on Wednesday. While there could be some breaks in the rainfall through Wednesday morning (especially along the Jersey Shore), the heaviest rain will fall through Wednesday afternoon and evening. The bullseye for the heaviest rain is in the western half of the state. By Thursday morning, the rain should have largely tapered off, but a few showers and sprinkles will remain possible through Thursday evening.
The GFS model forecast timing is about 3-6 hours later than the NAM. So the first raindrops would be in South Jersey early Wednesday morning, with the entire state needing an umbrella by the Wednesday morning commute. In this scenario, the heaviest rain is still pegged for Wednesday afternoon and evening. A few showers may linger through midday Thursday.
The Euro (ECMWF) model starts later and ends sooner than the others, but also includes some very heavy rain in the middle. Onset of the rain is forecast to occur around sunrise on Wednesday morning. Some very heavy rain would develop through Wednesday afternoon and evening. Showers could continue through the Thursday morning commute, but the rain should end shortly thereafter.
Notice a pattern in these three narratives? That's called CONSENSUS and gives us higher confidence in the final forecast. For now, Wednesday looks like a washout for at least the western and northern parts of the New Jersey, with the heaviest rain bands setting up during Wednesday afternoon and evening. Some of the other details, such as the exact timing of the first drops and the last drops, remain questionable at this time.
Widespread 1+ inch rainfall totals are expected, with pockets of 2 to 3 inches of rainfall where the heaviest rain bands set up. Overall, a good soaking rain. Flash flooding and river flooding could occur as a result of heavy downpours.
The latest model runs have persistently shown the heaviest rain to occur along the NW corner of the state. It's important to "blur your eyes" a little bit when looking at rainfall total maps, as the bullseye could ultimately shift a few dozen miles in either direction. So even those along the coast need to stay vigilant to the possibility of torrential rains.
One particular element working in our favor is the antecedent soil moisture condition. October has been a very dry month across New Jersey, and so the ground is also dry... and thirsty! Given the dry conditions, the soil should easily soak up any light to moderate rainfall.
Even so... I say it often, and I will say it again... Never underestimate the moisture of a storm system with a connection to tropical moisture. This system used to be one of the strongest storms ever recorded, and it will maintain a moisture connection to the Gulf of Mexico as it swings toward the Northeast. The rain could be torrential, and the flooding could be dramatic in a few places during the heaviest downpours.
5.) Coastal Flooding
This storm is coming from the continental (inland) side of New Jersey, so the threat for massive storm-induced surge is minimal. However... There is a period of easterly winds in the forecast for part of Wednesday. That on-shore flow could result in slightly higher than usual water levels during the times of high tide. No need to panic though... Surge models are showing a tidal increase of less than one foot... The coastal flooding threat should stay low, limited to minor flooding of low-lying areas along the immediate coast. (In other words, the places that almost always flood when there is a storm.
6.) Other Impacts
If the heavy bands of rain really get going, there could be a few flashes of lightning and rumbles of thunder along the way. Severe thunderstorms are possible, but unlikely.
Marginally gusty winds are the other concern from this storm... I see sustained winds topping out at about 25 mph, with potential gusts as high as 40 or 50 mph. It might be worthwhile to tightly secure or bring in those inflatable Halloween decorations, so they don't end up down the street.
7.) Action Steps
No, this is not a "gotta get the bread and milk" storm. This will be a persistent period of rain, heavy at times, with some marginal wind gusts and the chance for flooding.
I see no reason to change your daily routine for Wednesday and Thursday - just be vigilant, be smart, and be safe.
8.) Beyond the Storm
A cold front will kick the storm out to sea, and then a large area of high pressure moves in for Friday and the weekend. That is great news for trick-or-treaters, as clear skies are ahead for Halloween on Saturday. It could be a bit chilly though, with daytime highs in the mid 50s and nighttime lows in the lower 40s.