2024 Indicators: SST's, MSLP, Shear, SAL, Steering, Instability (Day 16+ Climate Models)

[Woofde]

The tropical waves this past month have just been pathetic. As a comparison I found a shot from Late June. Even if you ignore Beryl the other two areas are more bundled together and healthier.

It's pretty clear now that the ITCZ shenanigans over Africa were underestimated in their significance. They pretty much robbed the basin of vorticity, now we're just left with these anemic dried out waves.

[Teban54]

The tropical waves this past month have just been pathetic. As a comparison I found a shot from Late June. Even if you ignore Beryl the other two areas are more bundled together and healthier.

It's pretty clear now that the ITCZ shenanigans over Africa were underestimated in their significance. They pretty much robbed the basin of vorticity, now we're just left with these anemic dried out waves.https://uploads.tapatalk-cdn.com/20240901/aa58f408f2b764be292469c0ba36dd6c.jpg https://uploads.tapatalk-cdn.com/20240901/4128518ec5c4d3c3782bfb76cdeb1aac.jpg

A big red flag for me was that the 10/40 wave had everything going for it last night: stacked vorticity (free from the competing lobe problems that models were expecting to happen for days), a weak surface low, and relatively low shear. Yet, the wave simply couldn't maintain convection during DMAX. I think that was likely a main contributor to model downtrends during 0z and 6z, as it's already causing the system to decouple (even accounting for the well-modeled acceleration to the west today).

[REDHurricane]

Not looking great right now, but if this wave can pull up that bundle of moisture from South America (just like Beryl and Ernesto) once it enters the Caribbean I think it's got a pretty good chance:

[MarioProtVI]

 https://x.com/webberweather/status/1830280739969261942




As I thought, something changed dramatically in late July that resulted in the unfavorable pattern across the basin and is smothering any TCG.

[Stormybajan]

Well, its September 1st, THE peak month of any Atlantic Hurricane season... its time for the season to either put up or shut it up! This 2024 season was not to just be any other above average or hyperactive year, it was forecasted to be a top 10 activity season! The most hype we've ever seen for a season in the Atlantic, and truthfully it hasnt played out like anyone couldve expected, June Category 4 making it the strongest hurricane for the month, continuing into a caribbean cruiser , earliest category 5 ever seen in the basin by some margin in Beryl, then when August comes around it finishes 2-2-0 being an absolute struggle bus in the last 10 days of the month when it should actually be picking up in activity. If I had to make a range now it would be a floor of 12-6-2 with 90 ACE and a ceiling of 17-9-4 160 ACE. Anything 180+ at this point is out of the question, however there will be some activity at some point this month and in October, I just dont see the basin making a 1961,2017-esque explosion train of activity. Theres been a ton of theories thrown around why its been so quiet in the last 11 days but I would lean more on the side of northern placed ITCZ and significant SAL outbreaks hindering the season. The Atlantic basin is the only basin where a seemingly slam dunk forecast is twisted into something completely different so regularly lol, funny what this basin can do to us tropics lovers. Its a post from a user being skeptical of the rest of the season and I hope its not seen as "season cancel" as I've read in the last 2 weeks any skepticism is placed under that bracket for some reason
SAL as of September 1st definitely looks strong for whats usually considered the express wave train time period of the season.

[WeatherBoy2000]

I think it's now safe to say that a crazy season like 2005 or whatever is off the table, but it's definitely not over yet.

Here are some examples:

2022 had 6 hurricanes after September 10th including 2 majors

2020 had 6 hurricanes including 5 majors during just the October-November period alone

2016 ended with four major hurricanes but three of them formed after September 28th.

2001 ended with nine hurricanes including four majors but didn't see hurricane activity until the second week of September

1998 was backloaded, 7 out of the season's 10 hurricanes formed after September 15th.

[Emmett_Brown]

IMO, this season might pull off a repeat of 2022’s lull period, except the lull will be delayed by a few weeks.

The current SST configuration resembles that of 2022 during the same time period, complete with the (shifted east) high-latitude warm blob and the relatively cool tongue of waters near the African coast. It seems that this year, however, the dry air problems are more to the east near the African coast, which has worked in tandem with the hyperactive African Monsoon to starve any waves of convection and/or concentrated vorticity.

https://i.imgur.com/AZmEpyZ.gif



One thing that also caught my eye is how 2024’s SST configuration changed from something resembling 2005’s in July to something closer to 2022’s configuration in late August/Early September. The warm blob also shifted to the SE during this timeframe, which is probably why dry air wasn’t so much of an issue in early August compared to now.

https://i.imgur.com/LkqjiKZ.gif


If we assume that this year does in fact follow 2022’s progression from now on, then we still shouldn’t let our guard down (i.e., Fiona and Ian). The key differences this year (1st-year cool neutral instead of 3rd-year moderate La Niña; any possible effects from the Hunga-Tonga eruption being less prominent due to the stratosphere recovering from the influx of water vapor) might mean that once the now-delayed switch does flip, then the spike in activity like we saw in September 2022 will likely last just as long or even long than 2022’s.

Yeah, you’re right; I went back and read some of the 2022 indicators thread and the early September posts were very similar to what’s happening this year. There were no named storms in Aug ‘22, and things got much busier in September (ie Ian etc)

[aspen]

 https://x.com/webberweather/status/1830280739969261942




As I thought, something changed dramatically in late July that resulted in the unfavorable pattern across the basin and is smothering any TCG.

Dang, Eric called this a 2013-level bust.

[Teban54]

 https://x.com/webberweather/status/1830280739969261942




As I thought, something changed dramatically in late July that resulted in the unfavorable pattern across the basin and is smothering any TCG.

If +NAO is the reason, that will likely change soon as current forecasts call for a more neutral NAO and perhaps even flipping into -NAO beginning in 5-7 days, as Andy Hazelton also noted in a reply to this tweet.

I'm pretty sure we've had many +NAO reasons in the past without any issues with activity, though.

[NDG]

 https://x.com/ndgmetchef/status/1830324989435773209

[Teban54]

 https://x.com/ndgmetchef/status/1830324989435773209

I don't know anyone that thought Debby had struggled. The highest peak NHC had ever forecast for it was 80 kt, which is still a Cat 1, and within the margin of error compared to the actual peak (70 kt). Anyone who seriously expected it to become a major was probably just -removed-.

[storm_in_a_teacup]

It’s so crazy how quiet August has been.
Like I remember we had Harvey and Laura by now in previous years.

I’m hoping we can run out the clock to mid-September because by then Texas won’t be as likely to be hit anymore. After Beryl it is clear Houston is not prepared for anything really

[Ubuntwo]

https://x.com/ndgmetchef/status/1830324989435773209?s=46

How would two hurricanes in early August make one think we'd be looking at disturbances struggling to even develop in early September? Completely defies climo and conventional thinking. I don't think anyone can truly say they saw this coming.

[aspen]

 https://x.com/ndgmetchef/status/1830324989435773209

I don't know anyone that thought Debby had struggled. The highest peak NHC had ever forecast for it was 80 kt, which is still a Cat 1, and within the margin of error compared to the actual peak (70 kt). Anyone who seriously expected it to become a major was probably just -removed-.

Debby simply didn’t have enough time despite being over SSTs close to 32C. Perhaps there was an outside chance of it going bananas if the core managed to put itself together quickly.

Ernesto should be the one people point towards as an under-achiever. Forecast to become a MH, but due a combination of its broad circulation and nearby dry air, it constantly struggled until that last bit of intensification over the northernmost Gulf Stream (which was probably higher than its operational peak).

I compared Ernesto to Earl ‘22 even early on in its life, and seeing how this season is a comparable under-performer to 2022, those comparisons are becoming more justified.

[Ubuntwo]

https://x.com/ndgmetchef/status/1830324989435773209?s=46

I don't know anyone that thought Debby had struggled. The highest peak NHC had ever forecast for it was 80 kt, which is still a Cat 1, and within the margin of error compared to the actual peak (70 kt). Anyone who seriously expected it to become a major was probably just -removed-.

Debby simply didn’t have enough time despite being over SSTs close to 32C. Perhaps there was an outside chance of it going bananas if the core managed to put itself together quickly.

Ernesto should be the one people point towards as an under-achiever. Forecast to become a MH, but due a combination of its broad circulation and nearby dry air, it constantly struggled until that last bit of intensification over the northernmost Gulf Stream (which was probably higher than its operational peak).

I compared Ernesto to Earl ‘22 even early on in its life, and seeing how this season is a comparable under-performer to 2022, those comparisons are becoming more justified.

The dry air Ernesto was dealing with was being sucked in from quite a distance. A compact storm wouldn't have had that issue - its problems were really structural. You could argue the broad nature of the disturbance Ernesto originated from was an indicator, maybe? Then again, 2020 had the exceptionally broad pre-Isaias.

[Teban54]

 https://x.com/ndgmetchef/status/1830324989435773209

I don't know anyone that thought Debby had struggled. The highest peak NHC had ever forecast for it was 80 kt, which is still a Cat 1, and within the margin of error compared to the actual peak (70 kt). Anyone who seriously expected it to become a major was probably just -removed-.

Debby simply didn’t have enough time despite being over SSTs close to 32C. Perhaps there was an outside chance of it going bananas if the core managed to put itself together quickly.

Ernesto should be the one people point towards as an under-achiever. Forecast to become a MH, but due a combination of its broad circulation and nearby dry air, it constantly struggled until that last bit of intensification over the northernmost Gulf Stream (which was probably higher than its operational peak).

I compared Ernesto to Earl ‘22 even early on in its life, and seeing how this season is a comparable under-performer to 2022, those comparisons are becoming more justified.

A problem with extrapolating the Ernesto vs. Earl comparison to entire seasons is that Ernesto occurred in early August, when dry air is significantly more common than when Earl happened in early September. Even if 2024 plays out like 2022 in the end, this specific comparison still sounds like a coincidence or a broken clock.

Edit: In some sense, Earl vs. Nigel is a much more apt comparison, and obviously that didn't extrapolate to their respective seasons.

[aspen]

I don't know anyone that thought Debby had struggled. The highest peak NHC had ever forecast for it was 80 kt, which is still a Cat 1, and within the margin of error compared to the actual peak (70 kt). Anyone who seriously expected it to become a major was probably just -removed-.

Debby simply didn’t have enough time despite being over SSTs close to 32C. Perhaps there was an outside chance of it going bananas if the core managed to put itself together quickly.

Ernesto should be the one people point towards as an under-achiever. Forecast to become a MH, but due a combination of its broad circulation and nearby dry air, it constantly struggled until that last bit of intensification over the northernmost Gulf Stream (which was probably higher than its operational peak).

I compared Ernesto to Earl ‘22 even early on in its life, and seeing how this season is a comparable under-performer to 2022, those comparisons are becoming more justified.

The dry air Ernesto was dealing with was being sucked in from quite a distance. A compact storm wouldn't have had that issue - its problems were really structural. You could argue the broad nature of the disturbance Ernesto originated from was an indicator, maybe? Then again, 2020 had the exceptionally broad pre-Isaias.

Perhaps. Broad waves do seem to be correlated with an active African Monsoon, something both 2020 and 2024 had (although this year’s Monsoon and AEJ are both unfavorably strong, and other factors are at play too).

What I was initially getting at with the comparison was that both Earl and Ernesto had very similar tracks, both had chances to become a major, and both fell short of expectations due to broad structural issues in La Niña years that unexpectedly underperformed. Perhaps a freak coincidence or a correlation.

[rockice]

We need major experts and science people to get to the bottom of what's going on

[NDG]

 https://x.com/ndgmetchef/status/1830324989435773209

I don't know anyone that thought Debby had struggled. The highest peak NHC had ever forecast for it was 80 kt, which is still a Cat 1, and within the margin of error compared to the actual peak (70 kt). Anyone who seriously expected it to become a major was probably just -removed-.

Debby struggled over the GOM for a whole 24 hrs to try to get a core going but dry air intrusion kept it at bay. Debby making landfall a whole 10 knots below the forecasted 80 knots by the usual conservative NHC says a lot.

The significant strengthening & rapid intensification never happened:

Debby will continue to move over waters of high heat content
and remain in an environment of low vertical wind shear into Monday
morning. Some dry air intrusion over the southwestern portion of
the circulation may have temporarily interrupted the intensification
process. However, given the favorable oceanic and shear
conditions, significant strengthening is expected before landfall.
Rapid intensification is especially likely if Debby acquires a
well-defined inner core.

[Ubuntwo]

https://x.com/ndgmetchef/status/1830324989435773209?s=46

I don't know anyone that thought Debby had struggled. The highest peak NHC had ever forecast for it was 80 kt, which is still a Cat 1, and within the margin of error compared to the actual peak (70 kt). Anyone who seriously expected it to become a major was probably just -removed-.

Debby struggled over the GOM for a whole 24 hrs to try to get a core going but dry air intrusion kept it at bay. Debby making landfall a whole 10 knots below the forecasted 80 knots by the usual conservative NHC says a lot.

The significant strengthening & rapid intensification never happened:

Debby will continue to move over waters of high heat content
and remain in an environment of low vertical wind shear into Monday
morning. Some dry air intrusion over the southwestern portion of
the circulation may have temporarily interrupted the intensification
process. However, given the favorable oceanic and shear
conditions, significant strengthening is expected before landfall.
Rapid intensification is especially likely if Debby acquires a
well-defined inner core.

The hurricane models never truly got above 75 knots, and 65-70kt was the consensus after the relocation + deepening below 1000 mb. Almost all models had a (slight) negative mean intensity bias per UAlbany, i.e., were a touch too weak. In fact, the hurricane models accurately captured a difficulty in getting to hurricane status due to environmental dry air, and most peaked at 60kt before it started organizing in the Gulf. The NHC were all alone at 80kt, applying their own judgement in considering the possibility of RI (where hurricane models are almost always too low). It was a gamble on their part that did not pay off. I don't think Debby is a meaningful indicator.