Tropical Storm Bertha update: Expanded watches and warnings along the Gulf Coast

[00:00:00]Tuesday evening everybody. David Paul with you here in the KHOU 111 weather center. It's 9:00. It's tropical update time. We've got tropical storm Bertha out there. Looks like it's going to interact with Louisiana in one way or another. Uh and that will determine how strong or weak it is once it gets over closer to Texas as we head into Thursday and Friday. This is the time of year July 21st. Here we are where statistically we begin to see a little bit more in the way of tropical activity. So it's not, you know, out of the ordinary to see a storm like Bertha forming here in the month of July. Uh it is quite common in fact and in fact, you know, if we stay on this track, we're on track for a normal season. We've got one in June, one in July. That's that's about normal for a hurricane season.

[00:00:45]We'll wait and see if we end up with our normal of 14 storms. Uh Colorado State forecasting nine named storms. Arthur and Berth are the two we've had. And I do read the comments uh here and other platforms. A lot of folks just mentioning the name Bertha talking about they had a grandmother Bertha or a great-g grandandmother Bertha. I had an aunt I had a great aunt Bertha. Just anecdotal. Apparently a lot of folks had a had a Bertha in their life somewhere back especially a grandmother or a great aunt. Great aunt Bertha was wonderful.

[00:01:18]She was just a wonderful lady. So I appreciate you bringing up the memory of that with the name Bertha. All right.

[00:01:25]Temperature. So, if you remember yesterday, we looked at sea surface temps. This was 87 degrees yesterday, I believe. Now, it's down to 86. So, there's been a little bit of sea surface temperature cooling here in the vicinity of where our tropical storm Bertha has formed. And you'd expect that cloud cover, rain showers, you're going to you're going to cool the surface a little bit, but still anything 80 or above is the threshold for tropical development. We're plenty warm. While we're on sea surface temperatures, couple of things. This is the sea surface temperature anomaly. So you're looking at where you're in the orange and red, that's above normal. The the white and blue getting to below normal.

[00:02:03]The Atlantic basin sea surface temps are overall a little bit above normal, but they're much cooler than they were last year at this time. Could be another factor in a below normal season. We'll see. And the blue regions here in the Caribbe, that's a lot uh of upwelling off the northern coast of South America.

[00:02:21]We've got several spots here where we've got upwelling and there's some pockets of cooler water in there. But we are focused on the Pacific because this is the El Nino region.

[00:02:31]We are in an El Nino right now. El Nino advisories been issued. The forecast is for a strong El Nino through winter of 2027. So 2026 2027 winter strong El Nino forecast to continue. That usually brings heavy snow to the Rocky Mountain West and the Sierras and the Shastas and the Syscuses of the Western United States. We'll see if that happens. But the reason we monitor this for tropical season is because statistically we have noticed that when we get an El Nino, especially a strong one, what we see is stronger upper level shear across the Atlantic basin blowing west to east and that can also suppress hurricane activity. wind shear uh disrupts the circulation, makes it difficult for storms to form, and it can it can fizzle out storms that have already formed. But what I find really interesting about what's going on right now with Bertha, it is undergoing a lot of windshare.

[00:03:27]That's a big factor in Bertha is that it's being sheared, but it's not westerly shear. It's not what you would expect. It's not coming from west to east.

[00:03:39]It is coming around this big ridge of high pressure coming in from basically east to west.

[00:03:47]It's coming in exactly the oppa direction that statistically we would expect the higher shear during an El Nino hurricane season, but that's weather for you. It's surprises. So, this big sprawling area of high pressure at the upper levels, this upper level ridge of high pressure centered here north of Dallas is sending all this shear out of the out of the east to west across the top of the storm and keeping it significantly disrupted and significantly weaker than it would be if it was in an unshared environment.

[00:04:18]Here's the latest on Bertha 7 o'clock update Tuesday evening. 60 mph max sustained winds. That's on the southwest side in that convection where they found that outside the convection the winds are not as strong, not nearly as strong.

[00:04:32]It's breezy, but you're not getting 60 mph winds. We've had a gust of 70 measured by the hurricane hunters that were in there moving west at six.

[00:04:40]Pressures at 997 millipars. And you can see how everything is being blown off to the west. These are surface winds.

[00:04:50]There's your surface circulation at last check right there.

[00:04:54]So all this convection is removed from the low-level center. Uh it is a completely lopsided system because of the wind shear. So that's the surface wind. Here is your upper level wind flow. And there you can see the shear cutting across from west to east right across the storm. And that shear as this storm heads west, it's going to head into even stronger westerly shear here. That is a major factor in the intensity forecast dropping off the intensity of the storm after tomorrow as it moves west into more shear. Also, it will interact with land to one degree or another. So, there's a lot working against the storm strengthening. I'm surprised it got as strong as it did. It was forecast to go to 50 today, made it to 60. It's overperformed a little bit. Forecast track from the hurricane center as of uh 7 o'clock. This is actually the 4:00 track. You get a track at 4:00. We'll get a track update at 10:00 tonight on the news at 10. So, we'll have an updated track, but I'm not expecting any significant changes from here on out.

[00:05:58]Forecasting a 50 mph tropical storm to interact with, you know, the mouth of the Mississippi River, Lake Pont Train, New Orleans tomorrow. But I think those 50 mph winds are going to be on the south side of that storm as everything is sheared. So, I expect New Orleans to have a breezy, maybe a gust of 30 35 with a few scattered showers on Wednesday. Tonight and Wednesday, the storm weakens to 45 miles an hour by early Thursday morning. So, Wednesday night, Thursday morning, and then between Thursday morning and Friday morning, it will weaken to a depression.

[00:06:36]That's the forecast. It really depends on how much it interacts with land right in here uh tonight and tomorrow. If it's a little further inland, we could see it down to a depression before it exits the Louisiana coast. If it stays south, it could stay a tropical storm. We could have a tropical storm birth that come into the to the middle of Upper Texas coast as we head into Thursday night and early Friday morning. However, even if we were to get a tropical storm, it still looks like the system was going to be heavily sheared and very lopsided, which would put all of the heavy rain here.

[00:07:13]It wouldn't even be in the track. It would be blown off to the southwest.

[00:07:16]You'll see that in the forecast modeling here as we move along. So, a very unusual setup for a tropical system.

[00:07:24]Uh modeling for radar goes into Wednesday afternoon tomorrow. Latest high-res modeling actually keeps the low level center just off the coast. That would suggest it maintains its integrity as a tropical storm. Breezy day for New Orleans. A few scattered showers.

[00:07:39]Lopsided system though. Everything off to the south and west. South. Yeah, south and west of the center. Most of the thunderstorm activity. We go into Thursday 6:30 in the morning. At this point, modeling has an elongated low a low-level circulation. I don't know if that's a uh I don't think that's still a tropical storm. That's probably a depression or weaker as everything is being sheared off to the south. Look how all the thunderstorm activity is further south.

[00:08:11]So, Thursday morning, we get a north breeze in Galveston and Houston. There may be a little bit of elevated surf and sea activity. I expect there will be two or three feet, but nothing over the top.

[00:08:24]We get into Thursday noon, isolated showers zipping around the circulation, most of the of the rain offshore.

[00:08:32]Thursday afternoon and evening, wind shift from north to south as the circulation moves to the west of the Houston area. And I find this fascinating and this is how I think this is going to play out. Whatever whatever circulation we get in here, I'm trying to draw a low pressure area. Everything is blown off to the southwest of the low.

[00:08:55]So, we may take, like we did with Arthur, a direct hit from the circulation and have a breezy, beautiful day on Thursday while rain is way down the coast, blown southwest by the upper level wind shear. Just a fascinating setup.

[00:09:15]One of the uh many products uh we get from the hurricane center. probability of tropical storm force winds. They're getting them right now, so we know we're going to have them. They may get a few tropical storm force gusts in in New Orleans. They're into the 30 to 40% range that they'll get a tropical storm force gust inland, but really almost all the tropical storm force winds are going to be offshore.

[00:09:40]And you see the forecast, maybe maybe we get a tropical storm force gust to 39 or above on the upper Texas coast going into Thursday, Thursday evening, but it's we're in the we're in the 10 to 20% chance for getting that. So, it's unlikely that we will see tropical storm force winds in Houston Galveston according to this product uh from the hurricane center.

[00:10:04]So, as far as trying to just pin down what our local impacts will be in the Thursday, Friday time frame, and really it's Thursday, um we get a north breeze, 15 maybe gusting to 30 and as you saw that shifts around. It goes from out of the north to out of the east, out of the south during the day, afternoon, evening on Thursday.

[00:10:26]And then Friday being on technically the wet side, we might see a scattered shower. So, I've left in a 20 to 30% chance for scattered showers. But you saw in the modeling, it just doesn't look like much for the Houston Galveston area. Much better rain chance from Corpus down to the valley of Texas. Even though we may get the official center near us, they're going to get all the rain. We always look at this uh GFS and Euro, the two big global models starting now, and they have picked up clearly on our tropical storm. Both the models in red and yellow, the American model in yellow, the Euro in red.

[00:11:03]We move forward in time and the globals continue to have a little further northerly track just a little bit. This is Wednesday morning.

[00:11:13]They're going to bump it into uh Lake Poncha Train and New Orleans and then dissipate it rapidly as it interacts with land. By the time we get to Thursday and what there is of it moving into Texas, the circulation is gone. According to the global models, the American and the Euro, again, we look at the high-res modeling a minute ago. It maintains a little circulation that kind of broadens out like this as it approaches the Texas coast and weakens.

[00:11:41]So, we'll go further out in time. We go into Sunday, Monday, and we see nothing new in the region that we would be concerned with.

[00:11:52]Anywhere in here could get a storm into the Gulf and Houston. But on Monday, nope. We've got a mid- latitude low. A couple of them or depicted in different spots up near Halifax and Nova Scotia.

[00:12:04]Those head across the North Atlantic. We get a hurricane over here off the Pacific. This is Friday, July 31st.

[00:12:13]and we don't see anything bubbling up.

[00:12:18]So after Bertha, things look quiet according to the global models.

[00:12:24]And as far as Houston goes, I do want to point this out. So we have we have heat tomorrow. We've got an extreme heat warning tomorrow. We're going to see heat indexes as high as 115 tomorrow.

[00:12:35]That's what the modeling is suggesting.

[00:12:36]So, if you work outside, take breaks, slow down, early start, and then knock off early. But I want to also point out this 10% chance for rain. So, from time to time, our local high-res models have been suggesting that we're going to have a small handful of isolated thunderstorms in the Houston, Southeast Texas area tomorrow. That's on Wednesday. So, we've got heat. We have a chance for a thunderstorm tomorrow and that heat and with that much heat, if one gets going, it could produce some pretty good lightning and thunder. So, that's the possibility on Wednesday. And it's a weather impact alert day for the heat.

[00:13:16]As far as the rain chance, I think we get a breezy scattered shower chance of 30% on Thursday as the elongated remnant circulation or whatever form it's in gets closer to us from Bertha.

[00:13:29]Friday, it's it's exiting, but still enough to give us maybe a 30% chance for a scattered storm. And then after that, it all dissipates. And you saw the long range modeling, nothing new forming, and we go back to full-blown summer, upper 90s.

[00:13:42]Uh some models have us back to near 100 as we get toward the middle of next week. So, we're definitely in the hottest part of the summer for sure.

[00:13:51]This would be considered at least a mini heat wave with temps near 100. We got close to 100 today at Bush. We're forecasting 100 tomorrow. 101 on Thursday, 99 on Friday. That's where we stand right now. Still expecting minimal impacts here, but keep getting an update. Things can change.

[00:14:10]And again, we're going to get an update from the hurricane center with an updated forecast cone just before 10 o'clock. So, we'll have that on the 10 o'clock news at 10. And we'll see you then for our next live update.