Farewell Heat and Humidity, Hello Heavy Rain
After one more 90 degree day for the Garden State on Thursday, the chance for several of inches of rain and flash flooding enters the forecast.
Thursday will become the 8th and final 90+ degree day of this particular streak of hot weather. Yes, the heat and humidity will almost certainly come back at some point before summer's end. But it will be nice to get some extended relief as we prepare to close the record book on July this weekend!
Thursday morning will feature patchy fog, mostly sunny skies, and low temperatures generally around 70 degrees. As the day pushes forward, clouds will increase steadily. Humidity will be on the rise by Thursday afternoon too - it's going to feel quite muggy outside by the end of the day.
Our next storm system starts to push into New Jersey sometime between about 1 p.m. and 8 p.m. Thursday. The southwest corner of the state (near Salem County) will be the first in the state to see scattered showers and thunderstorms. The rain will then spread northward through Thursday evening and Thursday night.
Friday looks like a very wet day, with steady (and occasionally heavy) rain continuing through at least the middle of the afternoon. This extended period of rain and thunderstorms presents two potential problems:
1.) Gusty winds: The best chance for strong to severe thunderstorms will come during the front-end of our rain chances, on Thursday night. As we have seen multiple times this month, 40-60+ mph winds are sufficient to down trees, cause power outages, blow away lawn furniture, and make for some pretty nasty conditions.
2.) Flooding: By far, the bigger risk will come from sheer deluges of rain. Upwards of 2+ inches of rain is possible from Thursday night through Friday, which can easily and quickly inundate streets, streams, creeks, and other low-lying areas. (This type of water inundation is aptly called "flash" flooding.)
The National Weather Service has issued a Flash Flood Watch for central and southern New Jersey (south of Interstate 78) from 6 p.m. Thursday until 7 p.m. Friday. Remember a watch is simply a "heads-up" of potential bad weather, notifying you that any rain storm during this time frame is likely to cause flooding problems.
I'm leaning pretty heavily on the NAM model for this rainfall forecast - I think it shows the most reasonable progression of precipitation, although I also believe it undercuts temperatures a little bit.
According to the NAM, the heaviest bands of rain would occur around 8 p.m. Thursday in South Jersey and 11 a.m. to 2 p.m. Friday. The GFS adds another round of heavy rain Friday morning.
All that rain on Friday will limit high temperatures to the mid 80s - the wettest part of the state may not get out of the 70s through Friday afternoon.
Friday evening looks dry and pleasant, with lower humidity. That will lead to more comfortable low temperatures in the 60s by Saturday morning.
Saturday will almost certainly be the better day of the weekend, with a mix of sun and clouds and high temperatures in the seasonable mid 80s. It's not all good news, however, with a few thunderstorms possible. The best chance for showers and thunderstorms will be late-day (after 8 p.m.). However, the GFS model notably does include raindrops during the Saturday afternoon hours.
Steady rain makes a comeback for most of Sunday, making for a soggy end to the weekend and the month of July. I literally have rain chances in the forecast from 5 a.m. Sunday through 8 a.m. Monday, with a widespread inch of total rainfall possible.
After the double rounds of rain, we'll fall into a drier pattern for the first week of August, with comfortably warm temperatures in the mid 80s. Don't get used to it though - as long-range models show another significant warmup could be in the cards by next weekend.