00:00In the forecast feed we have a lot to talk about with severe weather possible in many communities in the
00:06Midwest and Northeast during fireworks time.
00:10And the positive side of this is that we're going to get some relief. The heat wave will be ending.
00:14It's not over yet.
00:15Let's take a look at the details. We're going to really do our best to try to time out the
00:20most likely areas to actually see thunderstorms in that late afternoon and evening time frame.
00:26To some extent, if we get too specific, we'll be trying to do the impossible because these storms are small
00:33scale and down to the county level 24 hours in advance.
00:37You just can't do it. But we can give you the idea of where the storms will be most likely,
00:42at least in a broad scale area, what parts of what states are going to be most likely to see
00:47storms at what times and so forth.
00:48So thunderstorms are going to interrupt plans. They will bring relief. It is good news and bad news all at
00:55once.
00:55And as we look at the worst of the severe weather, that's probably going to be most focused into the
01:00Midwest.
01:00And we have extreme amounts of moisture. I'm going to show you the dew point map here in a moment.
01:05I was tempted to go extreme for warmth as well for the Northeast. That is the case.
01:10But for the Midwest, the heat is beginning to back off.
01:12So kind of playing it this way here, high amounts of heat, extreme amounts of moisture and moderate amounts of
01:19jet stream energy.
01:21Let's look at the details here. Let's get into it here.
01:24And overall, as we look at the overall flow, the heat dome that has been with us for days this
01:31week, initially over the Midwest, then it moved into the Northeast and the Mid-Atlantic.
01:35There it is. This is a position as of technically this was 2 p.m. Eastern earlier this Friday.
01:42But moving forward, you're going to notice that this 594 contour is going to disappear.
01:49It's like a mountain of air. And if you're doing like a topographical map, we're going to not have to
01:54use that contour beginning on Saturday.
01:57In other words, the mountain of hot air is beginning. The dome is beginning to shrink just a little bit.
02:02And it's not a coincidence that this disturbance here, which is a cold front, there's a cold front tied to
02:08that, that's going to take a bite out of this.
02:10As that moves into New England, even though that disturbance on its own is in New England, it certainly kind
02:16of beats down the ridge.
02:18We begin to see that begin to get squashed a little bit.
02:22So overall, that's the big idea. And as this trough sets through, it's going to bring some little bits of
02:30energy along with it.
02:31Here's one on Saturday evening and areas near and east of that.
02:35There's a little bit of an enhancement and lift in the atmosphere.
02:37But here is the NAM. This is another model.
02:39And you can see if those bright colors are to your west, then you're in a position where there's going
02:43to be more lift in your area.
02:45You can see across the Northeast, many areas east of one of them.
02:48We have another trough moving through parts of Wisconsin.
02:53Again, we're going to be dealing with extra lift in that area.
02:56And that's actually the stronger jet stream disturbance that penetrates some of the heat and humidity.
03:02As the New England trough is strong, but it just kind of bypasses the worst of the heat by the
03:06time we get to Saturday.
03:07Sunday, another disturbance moves in.
03:09And this one, Sunday evening and Sunday night, is going to be a fairly broad trough across the Midwest.
03:13So we've got a few days of trouble.
03:14But I want to get more specific for July 4th.
03:17That's probably what many of you care about the most.
03:19And this is what motivated me to do that extreme for the moisture.
03:24This, like a deep blue, beyond that sea green blue, beyond the teal, that is dew point of 75 plus.
03:3275 plus degree dew point.
03:34That is tropical air.
03:35Tropical air there in the Midwest.
03:37Very high fuel for thunderstorms.
03:39It's very humid in the Northeast as well.
03:41But man, that moisture is rampant.
03:43And you can see the NAM also brings, and this probably lines up with reality, has a slightly higher resolution.
03:49It's also showing 75 plus degree dew point air surging up north through the Chesapeake Bay region,
03:55which is an area of very high moisture.
03:57It's a moisture source up into areas around Gettysburg, PA as well.
04:01So that's Saturday.
04:03Lots of moisture.
04:04Let's look at the fuel for storms.
04:06This is convective available potential energy, CAPE.
04:09It's this concept of hot, humid air near the ground and colder air aloft.
04:13Now, over the Northeast, these values don't look that impressive, right?
04:18Your eyes probably draw into the plains.
04:20That's where the air aloft is colder upstairs.
04:23We have just so much heat over the heat dome that even aloft, it's pretty warm.
04:27So the contrast isn't all that significant.
04:30Warm, humid versus cold.
04:31It's warm and humid.
04:33It's hot and humid versus fairly warm upstairs too in the Northeast in a relative scale.
04:38So that's partly why the CAPE values are not as wild in the Northeast with the GFS.
04:43Now, the NAM, perhaps because it also has more humidity near the ground, near the Chesapeake Bay,
04:48this does indicate some pretty impressive CAPE here, 3,000 to 4,000 joules per kilogram.
04:54That's a lot of juice.
04:55And then the European, a little more timid.
04:58But again, something we have to keep an eye on.
05:00It's going to be, there's plenty of fuel for storms.
05:02There's no shortage of fuel for storms.
05:03Let's look at the high-resolution rapid refresh, HRRR, simulated radar reflectivity.
05:11This is taking us through 3 a.m., 4, 5.
05:15That's, what, 7 a.m., July 4th.
05:17Some showers up in upstate New York.
05:19We all care about the evening the most.
05:21I'm going to take this map into the Midwest in a little bit.
05:24But here we are into noon.
05:261, 2, 3, 4, 5 p.m., July 4th.
05:31Barbecues firing up.
05:32Look at this area north of New York City, Westchester County.
05:35Look out.
05:36D.C. look out.
05:37Also into Maryland.
05:37That's an area with, there's also a message in here that the HRRR, at least, is arguing
05:42for fewer storms in between until the evening.
05:45Here we are now at 7 p.m., 2300 Greenwich Mean Time.
05:51Subtract 4 hours, 7 p.m.
05:53And even these small-scale storms, I see one over, I don't know, Cheltenham, maybe areas,
05:58maybe like Bluebell, Pennsylvania there, northwest of Philadelphia.
06:02Small-scale, but again, if you don't want to take that too literally, those are thunderstorms.
06:06Those are concerning.
06:07And then 8, 9, 10 p.m., fireworks time.
06:11We got more widespread thunderstorms for many in the northeast, including Philadelphia,
06:14Allentown, and other areas.
06:16Let's take you into the Midwest real briefly.
06:18Similar time.
06:20Big storms roaming.
06:21This would be, all right, here we are at 7 Central, 8 Central, 9 Central.
06:26Cincinnati, Lexington.
06:27Look out.
06:28Up into areas like northern Indiana, the Chicago Metro.
06:31We're going to have storms around.
06:32Might be a little more likely near Rockford.
06:34But we have big concerns.
06:35We're going to close with a look at our fireworks forecast as we play this out here.
06:40We're most concerned about high, high likelihood of downpours in the Midwest.
06:44There are going to be many in the northeast as well.
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