[Tuesday] Tropical Storm Bertha Approaching the Central Gulf Coast

[00:00:00]Hi, it's Tuesday, July 21st, and what was once tropical depression 2 now has the name Bertha. So, as expected, this is now a tropical storm and is approaching the central Gulf Coast expected to bend generally towards the west as it bumps up against the central Gulf States. Areas from the western Florida panhandle through southeastern Louisiana are likely to begin feeling impacts today with gusty winds already moving ashore with heavy showers into the Florida panhandle. And these conditions will spread westward with the potential for tropical storm conditions and coastal flooding over the coming 24 to 36 hours. If we take a closer look at the storm this morning, we're likely witnessing Bertha at or near its peak intensity. You'll see very uh quick rotation now to the eye as the exposed low-level circulation pokes its head out from underneath of the lone thunderstorm clump within the inner core. All the actual thunderstorm activity in bulk is kind of confined to this really long and trailing band on the southern side. But if we look at the inner core, there's really just one big updraft here in the southeastern quadrant. The rest of the circulation is dry. I mean, not fully dry. There are showers in these low-level bands, but in terms of deep thunderstorms, there's not a lot going on on the north side. And we still have that dry air here that we've been talking about for several days. And now the streaming upper level flow out of the north and northeast hitting Bertha from the onshore side. And this is causing a lot of shear that is responsible for all the thunderstorms being confined to the south of the center. And this shear is increasing during the day today and will likely reach its maximum sometime during the next 24 hours. That didn't prevent the storm from gaining some intensity overnight prior to the strongest shear arriving. This is the aircraft reconnaissance data showing that the pressure fell to 996 mibars and you now see red and orange colors showing up on the eastern side of the circulation.

[00:01:57]These winds are up to 60 to 70 mph at flight level. If you reduce that down to the surface, that's 50 to 60 mph.

[00:02:05]Estimated surface wind. The last reported intensity from the National Hurricane Center was 50 mph max. That might be coming up closer to 60 on the next advisory here. I'll likely refresh it by the time I'm done recording. Uh the buoy right here to the southeast of the center has been reporting tropical storm force sustained winds at about 40 mph in the last hour or so. And the western side of the system has much less wind with it. In fact, we got a SAR image from RCM1 courtesy of the Canadian Space Agency and Noah Nezdus. And what you'll see here is everything in yellow is approximately tropical storm force and above. And you'll see this big band on the eastern side of where the low-level center is. So birth is centered right here. It's a very lopsided system. The max windb band is all to the east and occasionally rotating around to the north. So you can see how this area here might eventually scrape up against the coastline of Florida and points west during the day today and tomorrow. We're already getting elevated wind gusts along this portion of the Florida coastline here.

[00:03:10]In fact, I can show you a brief look at the surface observations and radar.

[00:03:14]We've had gusts near 35 mph at Appalache Cola and then around 25 mph at Panama City and points west here along the Florida panhandle. Birth is centered right about here on the radar imagery.

[00:03:26]You can see that showers are only scattered on the north side where it's uh rather dry. Uh but there are still heavy showers that will continue to translate towards the west today and tonight.

[00:03:40]If we look at the half's high resolution model forecast, we'll see what we have been seeing for the last couple of days and that's the impact of this shear. We have a big mid-level ridge over Oklahoma. So you see a huge flow out of the northeast around the nose of that ridge where Bertha is located. So the mid to deep layer shear is quite stark here at 25 to maybe even 30 knots out of the northeast. And so you'll continue to see this structure where the storm is centered here, but all the guts of the system are to the south in terms of deep thunderstorm activity. And as we continue forward, uh we're likely to see eventual weakening as the storm approaches the central Gulf Coast. We're expecting a turn toward the west. Now, there may be some wobbles in the storm center. Uh, one thing about the SAR image I forgot to mention is you'll notice that there's sort of a smaller ring of wind kind of within the larger donut. So, this indicates that some wobbling will likely occur as this tries to sort of orbit around the inner rim of the larger wind maximum. So, you might see it doing, you know, some of these as it moves towards the northwest. So, the short-term motion may be a little bit erratic, but over time, the thunderstorm clump on the south side is expected to uh kind of try to tug this towards the southwest at the same time that the low-level flow is trying to force this toward the coast. The net result of that is expected to be a westward turn in the net. We'll see how close this gets to the coast before executing that turn. Uh but regardless, some tropical storm force winds may scrape along the entire section of coastline here, which is why we have tropical storm warnings there.

[00:05:12]We can see what this looks like on the HASS model. You can see that ribbon of wind on the eastern side, just like we saw in SAR and aircraft data earlier.

[00:05:20]This will continue to funnel near tropical storm force winds inward toward the coast as the storm translates westward. So you'll see during its journey west, we continue to have the strong winds on the eastern side, occasionally wrapping around the north side. Everything in green here is tropical storm force, but the storm does begin to weaken a little bit on approach toward Louisiana. We don't see any further intensification due to the strength of the shear that continues to batter it from the northeast. And once the storm moves uh inland on the model over southeastern Louisiana, the weakening is accentuated uh due to the fact that it's no longer overwater. So, we see only a remnant low make it into western Louisiana and largely dissipated by the time it gets into southeast Texas where we don't really expect tropical storm conditions at this point. Maybe some elevated winds along the coast out of the southwest or south and some potentially localized heavy rains associ associated with the showers that the remnants bring into Texas, but probably much less impact than over here in the central Gulf Coast. So no warnings or watches out for that area at this time.

[00:06:28]These are the model track forecasts for Bertha showing general agreement on this turn towards the west near the Louisiana coastline or just over southeastern Louisiana. Again, there could be some wobbles shortterm due to the asymmetry of the storm. So some wobbles north of this track could bring more of the coastline here under the tropical storm force windfield. A track more towards the south would keep the strongest winds further offshore. So, we'll keep an eye out for that. You'll note that some models do show a track that largely stays technically offshore of southern Louisiana. That remains a possibility.

[00:07:03]Although, right now, it doesn't look like the storm is taking the more southerntherly of these routes. If it were to remain near the coastline or offshore, it could remain a tropical storm for a slightly longer time as it passes south of Louisiana. So that could expand some wind and coastal flooding related impacts a little farther west along the coast. But even if it does stay overwater, shear is expected to remain strong this entire journey and weakening on its approach towards southeastern Texas is the expectation regardless of whether the storm is tracking over land or water. This is the official National Hurricane Center forecast. I just refreshed it. This is the 10:00 a.m. Central time advisory just coming out as I'm recording. You can see the forecasted westward track near the southeastern coast of Louisiana near the Mississippi Rivermouth on Wednesday evening. Tropical storm warnings in blue along the coastline extending from the western Florida panhandle through Alabama, coastal Mississippi and southeastern Louisiana with tropical storm watches around Lake Ponatrain and central Louisiana coastline and expecting weakening from this point forward. So, the hurricane center did raise the intensity to 60 miles per hour as I expected from the aerial reconnaissance observations that we talked about earlier. Uh, but they expect no further intensification from this point. And that makes sense given that conditions are worsening for the storm and its structure will likely degrade over time going forward. Now again, weakening expected regardless of whether it's technically inland or not over Louisiana with tropical depression intensity expected by the time it arrives in the Houston area of Texas.

[00:08:44]There will not be a whole lot left of this by that time. In all likelihood, models have a broad consensus uh that this will be weakening with most of the heavy rain remaining offshore. In fact, we can see that in the rainfall forecast where at least for the short term, this doesn't quite extend the forecast all the way to Texas. But you can see how most of the heavy rain is in fact to the south of the continent. So although some rains will of course affect land areas and some localized heavy showers uh could cause a few inches of rain here and there, the bulk of the water coming out of the sky will be offshore over the ocean and that will hold true in Texas as well. But expect an uptick in showers nonetheless. There will also be some coastal flooding concerns. We do have, you know, a fist of wind driving water towards the coastline. So, some water level rises will occur, especially in this floodprone region where the coastline bends like this. Some water getting piled up in here could lead to 2 to 4 feet of coastal inundation. So, some mild coastal flooding uh could occur here. So, be aware of that.

[00:09:48]Flooding much more dangerous than wind with this system where flooding does occur.

[00:09:54]That's about it for this video. We'll continue to track Bertha. Again, likely at peak intensity here as it begins to spread. Tropical storm impacts from east to west today and tomorrow along the central Gulf Coast. Thankfully, not a hurricane, but still could cause safety hazards. So, everyone, please be smart and stay safe out there. You can follow me on social media for more frequent updates. Tropical Tidbits on X, Facebook, and Instagram. That's it for now. Thanks for watching.