NJ weather: Final days of summer look delightful, rain midweek
The Bottom Line
The Autumnal Equinox is coming up this Wednesday 9/22 at exactly 3:20 p.m. That's the moment that the sun will be directly over the Equator. Equal day, equal night. The halfway point between the summer and winter solstices.
And what do you know, we have quite a seasonal transition ahead this week. We start with a continuation of this weekend's delightfully dry air and dry weather. Then a slow-moving cold front drives in our one and only substantial rain chance of the week.
By the end of the week, temperatures will trend noticeably cooler, Yes, a little taste of real fall weather on the way?
I don't know about you, but I was unabashedly celebrating the lack of humidity in the air on Sunday. A simply spectacular day.
So let's do it again, shall we? A dome of high pressure and dry air remains overhead Monday, leading to a comfortable and mostly sunny sky.
On this Monday morning, temperatures range from the chilly upper 40s in North Jersey to the cool upper 50s in South Jersey. Along the immediate coast, thermometers are significantly warmer (as high as 70) thanks to the influence of that warm ocean.
The only issue Monday will be a continued moderate risk of rip currents along the Jersey Shore. Ocean wave heights could be as high as 3 feet.
Dew points will slowly rise throughout the day, but I doubt you'll feel a difference. That change will have two effects on our weather Monday evening: increased cloud cover, and not-as-cool temperatures. We'll bottom out around 60 degrees by Tuesday morning.
Another pretty nice day, although cloud cover will become more prominent through the afternoon. Combined with a continued southeasterly wind, the Shore will end up on the cool side of normal, with highs in the lower 70s. We should see mid 70s once again farther inland.
I've opted for a dry "official" forecast for Tuesday, although a stray late-day shower can't be completely ruled out as humidity levels rise.
A very different weather day, as we change seasons.
First of all, skies will transition to mostly cloudy. That southeast wind will kick up to the "breezy" (20+ mph) or even "windy" (30+ mph) category. It's going to feel quite humid. And high temperatures will pop to about 80 degrees.
The big challenge for the second half of the week is that slow-moving front I mentioned earlier. Forecast models are having a hard time handling the speed and intensity of that storm system. One particular difficulty is that the remnant moisture of former Tropical Storm Nicholas is wrapped up in this system, raising the potential for heavier rainfall.
According to the latest info, I think we'll only see spotty showers on Wednesday. Maybe a spot thunderstorm. Most of the day should be dry.
When will this week's big push of rain arrive? Thursday seems to be the consensus at the moment. The GFS model says early Thursday morning. The Euro holds it off until Thursday night.
Forecast rainfall totals average an inch, which shouldn't be much of a problem. (Flash Flood Guidance is more like 2 to 3 inches in North Jersey, which has seen an incredibly wet September so far.) I have seen some hints of heavier 2+ inch downpours. That could be enough to cause some ponding and flooding issues. There could be some rumbles of thunder too.
Meanwhile, the NAM shows no period of heavy, steady rain. It's notable that the NAM is a shorter-range "mesoscale" model, by definition, and struggles with the forecast over 72 hours away. Still, it's worth considering that we see minimal rain, and just a burst of wind followed by cooler, drier air.
Friday & Beyond
By mid-morning Friday, rain chances will be over and skies will be clearing. We'll find ourselves back in a dry, cool air mass that should last through (most of) the weekend.
High temperatures will settle in the lower 70s or so. More typical of early October than late September. A real taste of fall.
The tropics are still active, with Tropical Storm Peter about 1,700 miles southeast of NJ and Tropical Storm Rose about 3,000 miles away. No direct threat to the U.S. East Coast. But Peter will threaten Bermuda, and could continue our rough surf and rip current concerns through the week.