Today, a weak cold front sits south of I-78 near Philadelphia. Behind the front, it's a touch cooler (upper 80s vs low 90s) for the Poconos, Lehigh Valley, and northern NJ. Closer to the front, it'll still be in the low 90s because the slightly "cooler" air hasn't arrived yet. This front will sit in the Philly area for the next two days, so you'd think temperatures would be similar on Thursday, but that's not the case because it'll be much cloudier. This will knock five degrees off Wednesday's highs.
Showers and thunderstorms like to form along and near a front so there will be a lot of storms--some with very heavy rain--this evening in the south (south of I-78). As for the rest of our area in the Lehigh Valley, Poconos, and northern NJ, expect showers and storms to pop up, as well. They just won't be as widespread as the south. Some of these storms will have heavy rain. While flash flooding is more of a concern for the south, any storm that sits over you and dumps 1-2" of rain will cause flash flooding. There is a flash flood watch for the Lehigh Valley and counties south in effect for this afternoon and evening. Some of these storms can dump so much rain because it's oppressively humid today. The other reason is that some of them will be slow moving. Tomorrow, the humidity comes down a touch. We'll still have showers and storms, with more in the south. Then, we start drying things out into the weekend. There will be only a few storms on Friday. After that, enjoy the drier weekend.
FLASH FLOOD WATCH IN EFFECT FROM 11 AM THROUGH THIS EVENING FOR THE LEHIGH VALLEY AND COUNTIES SOUTH.
On Tuesday night, a weak cold front crossed over us. It's weak because it only knocked a few degrees off our highs. For example, instead of 91 (Tuesday's high) in the Lehigh Valley, it's 89. Spots south of I-78, which are closer to Philly, will have a high around 90 because the front has not passed far enough south. Because the front lingers, it will serve as a focal point for showers and storms in that area. Expect rounds of heavy rain from thunderstorms in that region this evening. The rest of us will just see some showers and thunderstorms pop up. Some of those storms will have some heavy rain, too, but it won't be as heavy as it will be in the south.
It'll be rather cloudy tonight with some leftover showers and storms still around. Toward daybreak, we'll have some more fog.
This will be our cloudiest day of the week. The weak cold front is still sitting to our south, so it's more of the same. There will scattered showers and storms, particularly south of the Lehigh Valley, the Poconos, and Hackettstown. The rest of us will see a few showers and thunderstorms in the evening and some of the storms will have heavy rain. In terms of temperature, you'd think our highs would be the same as Wednesday, but there's more cloud cover in the sky so we're down in the mid 80s because of less sun. By the way, it won't be as oppressively humid on Thursday. With that said, it'll still be humid. It just won't be as bad as it has been.
We trend drier as we head into the weekend. On Friday, we'll have just a few showers and storms. Then, we've got dry weather for the weekend. While there will be some humidity this weekend, it won't be nearly as bad Friday, Saturday, and Sunday. Of the three days, Sunday will feel the least humid. Highs will be more seasonal in the low 80s (83 is the average high for this time of year).