Philadelphia Weather: Fast-Moving Thunderstorms

Kate Bilo reports.

Video Transcript

- Let's talk about the air and the conditions right now. The weather is about to take a nasty turn. Today was sunny and beautiful, but Kate you're saying the script is about to be flipped, huh?

KATE BILO: That is correct. It is going to feel downright cold here by Thursday morning, after this front that we're watching off to the west comes blasting through tomorrow afternoon. Enjoy this while we have it, because tomorrow is a transition day. It's not going to pour all day. But there will be a line of thunderstorms across the area in the afternoon, and that's going to bring about the big changes. Right now, you can see it's beautiful.

This was my view just a moment ago on the Skydeck. It's great. The sun is shining. Blue sky as far as the eye can see, and temperatures in the mid 70s. Enjoy it. 75 degrees in Philadelphia. Feels like 75.

The dew point is 36, and there's a pretty brisk breeze. From the south and west that was bringing in all this warm air, southwest wind at about 18 miles per hour. Now tonight, 54 degrees. It's still very mild. You can see winds do start to pick up even more.

These winds are starting to howl out ahead of this advancing cold front. It's a very strong system, a strong front. And a lot of times you get that southwest flow, that kind of blow torch flow, that really heats things up. But you want to feel the winds really pick up.

Tonight, it's still mild at 54 degrees. And tomorrow starts out mild. But by midday, likely between about 1:00 and 5:00 PM, a line of fast moving, gusty thunderstorms will roll through the area. And that'll knock out 68 down very quickly. Winds go from southerly to northwesterly by late afternoon, and could get gust high as 40 miles an hour outside of the thunderstorms. Winds even stronger than that, in any thunderstorm winds could just over 50, 55 miles per hour. So Stormscan3 shows where this system is.

You can see the snow breaking out on the back edge. Just a very clear indication of how much colder the air that is driving south behind this strong front. It's really almost the delineation between spring out ahead of the front and winter behind it. And this is coming through for us tomorrow. It's not going to bring snow for us, but you can see parts of even western and northern Pennsylvania could pick up 3 to six inches.

Some of the mountains up here in Vermont, New Hampshire may see upwards of a foot of snow with this system. For us, it's just the thunderstorm chance and then the brutal temperature drop. So overnight it stays mild, tomorrow we surge into the 60s to begin. A couple of showers early, then here are these fast moving storms will come through the city about 2 or 3 o'clock.

Gusty winds will be the biggest threat with any of these storms. They're out soon as well. But by 8:30 tomorrow night, we drop into the 40s, and we will be in the 30s to start your Thursday morning. So tomorrow is the transition day. Quick-hitting thunderstorms mid-afternoon, cold wind chills Thursday. It's not going to feel any better than the 40s all day long. It'll feel like the 20s when you wake up, but it does rebound quickly. 60 for Friday, 68 on Saturday. And then more rain, a soggy Sunday unfortunately on deck at 65 degrees. Jessica, we'll send it back over to you.

- OK, Kate. Thank you.