WxWatcher007

Tropical Depression Three Discussion Number 1 NWS National Hurricane Center Miami FL AL032023 1100 AM AST Mon Jun 19 2023 Satellite images indicate that the tropical wave over the central Atlantic has become better organized this morning. GOES-16 1-min visible imagery shows that the center has become well defined near a developing central dense overcast with prominent convective banding in the northern semicircle. The initial intensity is set to 30 kt, based on Dvorak estimates from SAB and TAFB, and recent satellite trends indicate this system is close to tropical-storm status. The initial motion estimate is 275/18 kt, a bit uncertain because the center has just recently become trackable. A large ridge of high pressure over the central Atlantic Ocean is forecast to cause the depression to move westward over the next several days. As the system nears the Lesser Antilles late this week, the ridge should weaken, causing the system to move more toward the west-northwest. However, there is considerable uncertainty in how much of a right turn could occur because it is somewhat tied to the intensity of the cyclone. A stronger system would tend to move more to the right due to the upper-level flow, while a weaker system would continue more westward into the Caribbean. For now, this forecast lies near the model consensus, and adjustments are likely in future advisories. This should be considered a low confidence track forecast since this type of forecast situation can result in large errors. Environmental conditions appear conducive for strengthening over the next few days, with a much warmer than normal ocean in the depression's path, along with plentiful mid-level moisture and light shear. This should promote strengthening through midweek. However, vertical wind shear is forecast to increase by most of the model guidance around day 3 in response to an upper-level trough. Thus the NHC forecast shows the intensity leveling off at the end of the forecast, consistent with the middle of the guidance envelope. This intensity forecast is also more uncertain than normal, due to the differences in the model suite, along with the aclimatological nature of this system. KEY MESSAGES: 1. The depression is forecast to strengthen and move across the Lesser Antilles as a hurricane on Thursday and Friday, bringing a risk of flooding from heavy rainfall, hurricane-force winds, and dangerous storm surge and waves. 2. Given the larger than usual uncertainty in the track forecast, it is too early to specify the location and magnitude of where these hazards could occur. However, everyone in the Lesser Antilles, Puerto Rico, and the Virgin Islands should closely monitor updates to the forecast for this system and have their hurricane plan in place. FORECAST POSITIONS AND MAX WINDS INIT 19/1500Z 11.0N 40.3W 30 KT 35 MPH 12H 20/0000Z 11.2N 42.9W 40 KT 45 MPH 24H 20/1200Z 11.7N 45.9W 45 KT 50 MPH 36H 21/0000Z 12.2N 48.6W 55 KT 65 MPH 48H 21/1200Z 12.8N 51.2W 60 KT 70 MPH 60H 22/0000Z 13.3N 53.9W 65 KT 75 MPH 72H 22/1200Z 13.8N 56.3W 70 KT 80 MPH 96H 23/1200Z 14.9N 61.5W 70 KT 80 MPH 120H 24/1200Z 16.5N 66.5W 65 KT 75 MPH $$ Forecaster Blake/Kelly

We’re about to find out the NHC’s first thoughts on track and intensity. If I were to hazard a guess, I’d say the first forecast would bring it to the northern Lesser Antilles as a 65kt system.

Oh it’s very strange. This is probably more for the tropical thread, but originally I thought the pattern (with a propagating CCKW) would set the EPAC off first. Crickets so far there. I’m not sold yet, but we may be seeing the first signs that the historically warm basin is screwing up how the Atlantic shear profile looks in what we would normally see in a strengthening niño. I mean this isn’t what I’d expect to see for the last half of June into July. Especially not in this ENSO profile. I think the other critical thing that’s being overlooked is that unlike past years—even the active ones—we are seeing far less stability issues and more moisture in the MDR as SAL has been anomalously low when it would be peaking climatologically. That’s a huge red flag to me.

Historic severe in the south…MDR lighting up like a Christmas tree…can’t buy a storm here yet

I’m not quite on board with believing this has implications for the rest of the season, but it’s increasingly hard not to wonder if the extraordinarily warm Atlantic is helping the atmospheric environment in the basin minimize the impact of the growing niño. If the niño fails to produce the typically high wind shear we see in the Atlantic, there’s no reason to believe that the season overall will be below normal.

Well, morning visible imagery shows that 92L has organized considerably overnight, and is on the cusp of becoming a tropical cyclone. It may very well be a close call for the Antilles as both the Euro and GFS have modest intensification before a close pass/hit.

Happy Juneteenth!

June 19th

Pretty consistent convection tonight with a robust mid level circulation (at least). Hard to tell if there’s a LLC under there.

Yeah, the ops have trended stronger with that one. A weaker 92L means less shear on this next wave. Feels more like August than June.

Not as much (deep) convection yet, but 92L remains on an organizing trend.

Yeah, certainly looks like an organizational trend the last 12 hours.

That’s insane.

Congrats E CT

I think you mean Binghamton.

Unsurprisingly, this evening the NHC designated the area of interest in the eastern Atlantic as Invest 92L. Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 PM EDT Fri Jun 16 2023 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Eastern Tropical Atlantic: A tropical wave located several hundred miles south of the Cabo Verde Islands is currently producing a broad area of disorganized showers and thunderstorms. Environmental conditions appear conducive for additional development, and a tropical depression is likely to form by the early to middle portion of next week while the system moves westward at 15 to 20 mph across the eastern and central tropical Atlantic. * Formation chance through 48 hours...low...30 percent. * Formation chance through 7 days...high...70 percent. Forecaster Papin TC genesis still needs to occur, but thus far this has been a remarkably well forecasted window for development, which @GaWx notes is highly anomalous against the historical record. There are a few reasons why this seems to be a very favorable window for development in the next week. First, SSTs are historically warm for this time of year. It's warm throughout the basin, but in the MDR it is particularly hot. Much higher than normal SSTs have allowed the MDR to be conducive at least thermodynamically. Why? In large part because of the mid/upper level pattern we haven't seen strong trade winds, or SAL, to temper warming in the MDR east of the Antilles. Just as important, we see a highly anomalous amount of OHC throughout the basin. This is a gif I quickly put together showing OHC values from 2016-2023 in mid June. And today's value as a single image: This is only one piece of the puzzle, however. In this region we also have reduced shear, and higher moisture levels, critical elements in TC development and survival that are usually hostile this time of year. It's about as good as it gets, currently. Here's the 12z EPS using 5 day averaged wind shear anomalies. This is an incredible look that has trended more favorable in recent days. Just as impressive is the moisture envelope. In recent years, dry air and stability put a cap on TC genesis and development, especially in the central and eastern MDR. That does not appear to be an issue this time, which again, is extremely impressive for mid-June. Coupled with the passage of a CCKW, and this all leads to a highly favorable environment IMO for TC genesis. This would be a highly favorable environment in September. It doesn't look like much now, but ASCAT shows that while elongated, it is trying to gradually consolidate. I think it will, and from there it'll be a question of 1) how quickly 92L can take advantage of the favorable environment, and 2) what the longer range steering pattern evolves into There's not much more to say yet, other than the operational guidance has become more bullish on intensification in the last 24 hours for the above reasons. As for track, while both ensembles (EPS/GEFS) look to favor an eventual recurve, it is extremely early to look long range on steering, though climo almost always favors a recurve, especially in the current upper level regime. I would watch closely in the Antilles.

It’s rains to Maine either way

That cell down near Fredericksburg looks nice.

I think it’s too early to say anything about the long range steering pattern, other than OTS is almost always the betting favorite for CVs. I think the weakness in the subtropical ridge makes it more likely we see a recurve, but the persistent troughing in the eastern US is something to watch, particularly since we’ve seen a lot of cutoff lows that could serve as a capture mechanism. Either way, this is highly anomalous, even though we had Elsa recently.

This is about as good as it gets for early season MDR activity. It’s an intriguing environmental pattern over the next 5-10 days.

This is a really interesting setup. Guidance getting more bullish as the wave tries to organize a bit today.