00:00In the forecast feed, we have our eye on many different things.
00:03We've been looking a lot at the tropics and the activity in the northern Gulf,
00:06but we want to shift our focus just for a few moments here
00:11to the severe weather risk that's going to be escalating.
00:13We've seen issues in the Midwest at the beginning of the week.
00:16We're moving forward Tuesday and Wednesday.
00:18The risk escalates into the eastern two-thirds of the Ohio Valley
00:22and especially into the northeast as well.
00:24Damaging straight-line winds will be our greatest concern,
00:27but we also have some other issues out there as well
00:30involving potential for some hail, isolated tornadoes as well.
00:33So let's take a look at the overall setup here.
00:37And here we are Tuesday, and there's our cold front.
00:41Everybody east of there has the risk of severe storms.
00:44So this includes the Ohio Valley all the way east.
00:48Now, the greatest risk for many of us here is going to be Tuesday afternoon and evening.
00:52You get into areas around southeast Virginia, into the Carolinas.
00:55The front's going to be making more progress east.
00:57But by the time we get to Wednesday, that's when we see the risk probably reach its peak
01:02down into parts of Virginia and off the map a bit down into some sections of North Carolina as well.
01:07Flooding will be a concern out there as well.
01:10So I'm going to be looking at some computer model graphics
01:12and showing you some of the insight behind our reasoning for these graphics.
01:16But the greatest flood risk, generally, PA Turnpike, I-70, and southward.
01:22And down through parts of southern Ohio, we had some flash flooding in the Cincinnati metro late last week.
01:30So the ground's been nearly saturated there.
01:32This is going to be more drought relief, but it does come with some trouble into the mid-Atlantic states
01:37and then into Wednesday, kind of really be more of a Tuesday situation up to the north
01:42and a Wednesday situation down to the south here, just given the timing of the front.
01:47Let's step away from our graphics and go to the computer models here for a moment or a few minutes.
01:53And big features on the map here that may jump out at you here.
01:57We have our, well, I can actually just draw the overall high-pressure system aloft over the interior west, over
02:05the Rockies.
02:05And then we have a big trough, low pressure over east-central Canada.
02:10It's bringing some good news.
02:11We have these recent wildfires that are getting some rain out of this in parts of northern Minnesota and just
02:17north of the border.
02:17But let's take this forward here.
02:19And we have a trough.
02:21I'm going to illustrate the trough.
02:22And here's the base of the trough here.
02:24It actually begins to go negative with the tilt.
02:29So this is a negatively tilted trough.
02:31I'm connecting the dots between the southernmost pouch of these height lines.
02:36You'll notice that in various different models, this is the European.
02:40I'll go back to the NAM and the GFS as well.
02:43Instead of it being tilted southwest to northeast or even directly north to south, this is close to directly north
02:49to south,
02:49it does gain a negative tilt here.
02:52Here it's a little more dramatic as we highlight connecting the dots between the lowest portion,
02:57the southernmost portion of those height lines.
03:01That's a negative tilt there with the GFS and then the NAM.
03:05Similar.
03:06When we get a trough that digs in that fashion, draped northwest to southeast or north-northwest to south-southeast,
03:13that is an orientation that really leads to more lift, more dramatic lift in the atmosphere.
03:19And that makes it a really punchy storm setup here Tuesday into Wednesday.
03:23The greatest risk is going to be Tuesday.
03:26Wednesday's threat for the mid-Atlantic will still be significant, but it's not going to be as high.
03:30Meanwhile, to the south, you can see our tropical system drifting west here as Bertha becomes more of a problem
03:36for Louisiana.
03:37So overall, here we are with our setup here into the northeast.
03:42And looking at the precipitation forecast, Tuesday afternoon, this is the rainfall from 8 a.m. to 2 p.m.,
03:47basically late morning to midday, Cincinnati, southern Ohio, look out, heavy rain.
03:52Moving forward, it's the evening when the I-95, including New York City, really gets into it.
03:57And we're going to be planning a YouTube live simulcast Tuesday, 4 to 8 p.m. because of this very
04:03threat.
04:03Yeah, we'll be talking about Bertha as well, but also a lot of eyes.
04:07The main impetus for us to do this is actually a severe risk for the short term for Tuesday.
04:12And here's the European looking at rainfall, 2 p.m. to 8 p.m., 8 p.m. to 2 a
04:18.m. Wednesday, Tuesday night,
04:20and then deep into the night, we'll see a new episode then on Wednesday here.
04:24For parts of the New England states, I don't think we're going to be as unstable by then.
04:29The greater severe risk may be down into the Carolinas by the time we get into Wednesday afternoon,
04:33but still some risk a little farther north until that front clears.
04:36And here's the European with that for Wednesday.
04:38I think the European actually plays this best, highlighting the severe thunderstorm hazards
04:43down into the Chesapeake Bay region, eastern North Carolina, South Carolina as well.
04:47Let's look at some other parameters out there.
04:49Here's the dew point surge.
04:50Man, it's really juicy air out there.
04:52Even in the short term, let's go to, say, Tuesday afternoon.
04:57I see this purple here.
04:58That is an 80-degree dew point.
05:01That's an 80-degree dew point.
05:03That's like really, really tropical air there in western Kentucky, in areas near and west
05:09of Elizabethtown.
05:10Is that overdone?
05:11Perhaps.
05:12But there is some other support for that in the NAM.
05:18Flirting with near 80-degree dew points in southern Indiana.
05:21In the European, there are some near 80-degree dew points there out near Paducah Tuesday evening.
05:27That is some really juicy air out there.
05:29And as we highlight the front, I'm looking at the wind streamlines here, converging.
05:34That really humid surge is right before the front arrives when we have that flow from the south.
05:40And then eventually, an abrupt shift in the wind will accompany those thunderstorms.
05:44Once we get into Wednesday, it's very juicy air to the Carolinas as well.
05:50Here's our front.
05:50You can easily see the dew point change there as well.
05:53Drier air follows this.
05:54But also, it's going to begin to shove some smoke back into parts of the Great Lakes area following the
05:59front.
05:59So, very humid air.
06:01Here is a look at the lifted index.
06:03This is a way of, it's kind of an old-fashioned parameter that looks at the updraft potential based on
06:09instability.
06:10Warp and humidity at the ground.
06:12Colder air aloft.
06:12You can see some very strong values there in southern Indiana with that high dew point air.
06:17The values aren't as incredibly high for the northeast, but they're certainly going to be high enough.
06:22It's very warm and humid out there.
06:24And the timing of this may be a factor in the lifted indices being maximized for the Ohio Valley.
06:29There is going to be some wind shear, but really this is moderate wind shear and stronger CAPE.
06:36The updraft potential is going to be maximized.
06:39One quick word here.
06:41Again, beyond the severe weather risk that we're facing for most of the northeast,
06:45we're also going to be facing some potential for some wildfire smoke.
06:48It won't be as thick behind this system.
06:50So, that's your forecast feed.
06:52Severe weather threatening the northeast Tuesday, Tuesday evening.
06:54We're going to be facing a few miles away.
06:54We're going to be facing a few miles away.
Comments