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

[Spacecoast]

Tropical activity doesn’t reference a calendar hanging on a wall. Just too much hand wringing far too early. IMO of course.

This is very true. Every single month. However, it's been 116 years since a Hurricane formed in March.

Edit: There has never been a Feb NATL Hurricane, ( only 1 Feb TS)

[tolakram]

Tropical activity doesn’t reference a calendar hanging on a wall. Just too much hand wringing far too early. IMO of course.

Are you going to answer the question?

[Kingarabian]

https://twitter.com/AndyHazelton/status/1828569629720989776?t=68O-umqWldugrpc165vtOA&s=19

Probably due to the SOI being negative during June and July.

[weeniepatrol]

I know I’m basically saying down is up, but one reason why the easterly shear was so strong in the eastern mdr was due to westerly surface flow. Westerlies at the surface plus strong easterlies aloft is a much stronger shear than climo trades with strong easterlies aloft. Need the outflow out of Africa to relax. It has relaxed, a bit.

[LarryWx]

Today’s Euro Weeklies could be nicknamed “A Tale of Two Seasons”:

- Weeks 1-3 (9/2-22): remain only at ~50% of climo overall. These haven’t changed much for days other than a gradual decline.

- Week 4 (9/23-29/new week “on the block”): the first forecast for that week is for 120% of climo and it follows the prior week’s modest 70%. So, it’s seeing some kind of sudden change. If it were a reversion to climo, it would be only at 100%, not 120%. Also, this is the first time there has been any week at 120%+ since the 8/16 run. Will be interesting to follow.

Any thoughts?

[chaser1]

https://twitter.com/AndyHazelton/status/1828569629720989776?t=68O-umqWldugrpc165vtOA&s=19

I'm not sure I buy Andy's reasoning regarding the more Nino like troughing in the mid-latitudes as having the role on this season's tropical cyclone output but I do believe there is one point that can clearly be gleaned from the ENSO side of the topic. It became increasingly clear to me starting from around the Spring barrier and each month thereafter, that the much anticipated moderate Summer Nina had continued to be a goal post that was getting pushed back more and more. What effect a cool neutral to weak Nina "might" have on the waning weeks of the Atlantic season has yet to be determined. The point that I wanted to make is this. How different might have Atlantic MDR conditions been had a significant Nina truly began to occur during the May/June/July period? Would we have had the same extent of dry air intrusion that seemingly has occurred? If in fact a warming tropopause is at play (which is interesting from an upper level capping perspective), would that had still played out regardless of any ENSO pattern reversal?

[chaser1]

So what's the red letter date for identifying something is actually odd with this season? Sept 10th? 30th? 1st? I'm not talking storm numbers, I think numbers are silly, but identifying an overall unexpected seasonal issue that is preventing development?

Mine is the Sept 10th. If we're still waiting for the models to show something on the 10th with no activity then there's clearly an unidentified issue that we should be able to learn from. If it picks up and we end up having normal to above normal then while we might bemoan a busted forecast I don't know if there's much to learn, other than seasonal variability can screw with any forecast.

5-10 Sep is a great choice for this.

Ditto, my thoughts as well. Genesis conditions had to be over the top for Beryl to have done what it did. Something not fully clear has since changed. No, the Hurricane Season certainly can not read a calendar.... and perhaps whatever magic ingredient that was present resulting in Beryl, might out of nowhere suddenly reappear. Here's the thing though. It's very soon beyond a forecasting dilemma and practically reaching a point of "now-casting". Meaning if nothin's there... then nothing is actually there. I can almost hear it now LOL. Fast forward to October 10th ".... wow Euro weeklies are on fuego and just look how the MJO is forecast well outside the circle in 1 & 2. After those two sputtering September tropical abortions, it's looking like the last week of October & beginning of November are gonna be gangbuster". I think the models are actually doing a fairly good job. If the Atlantic were getting its MOJO back, I'm willing to bet that the models will suddenly begin to display greater continuity. If little has occured by Sept 10, and models remain fairly flat-line, then chalk it up to whatever you'd like such as Covid causing tropical waves to dry-hack. Of course, no such diatribe can be complete without the prerequisite "Caribbean high oceanic heat" and remember that it only takes one.

I still do think that this season will prove deadly for many. Ask me again in about 2 weeks though

[MarioProtVI]

GFS shows a wavebreaking-induced TUTT by Shanshan obliterating the second wave coming off and seems to persist to the peak of the season around September 10 or so. Clearly something is not right at this point with this season.

I think after this season is done (if it continues at the rate it’s currently doing, which is certainly a good likelihood - hyperactivity is practically out of the question now), some agencies are going to take a big hit for the very high numbers predicted at the start of the season. Clearly something has changed within the atmosphere since late July that’s caused the Atlantic to become hostile for any development. I think this seems like a variation of some of 2013’s problems but different and with some elements of 2022’s issues as well - instead of getting stuck in a spring-like pattern throughout peak season, it seems as though 2024 seems to have gotten stuck in some sort of quasi-late-July pattern and has not advanced since. It also seems like the ENSO may also be a factor, as I’ve read that the pattern resembles a more Nino-like pattern, which is notable due to the fact the EPac activity resembles a Nino-like pattern, despite being only in neutral. I could be wrong with these causes but these are just my two cents for this.

[Teban54]

GFS shows a wavebreaking-induced TUTT by Shanshan obliterating the second wave coming off and seems to persist to the peak of the season around September 10 or so. Clearly something is not right at this point with this season.

I think after this season is done (if it continues at the rate it’s currently doing, which is certainly a good likelihood - hyperactivity is practically out of the question now), some agencies are going to take a big hit for the very high numbers predicted at the start of the season. Clearly something has changed within the atmosphere since late July that’s caused the Atlantic to become hostile for any development. I think this seems like a variation of some of 2013’s problems but different and with some elements of 2022’s issues as well - instead of getting stuck in a spring-like pattern throughout peak season, it seems as though 2024 seems to have gotten stuck in some sort of quasi-late-July pattern and has not advanced since. It also seems like the ENSO may also be a factor, as I’ve read that the pattern resembles a more Nino-like pattern, which is notable due to the fact the EPac activity resembles a Nino-like pattern, despite being only in neutral. I could be wrong with these causes but these are just my two cents for this.

I mean, if Shanshan is the main reason for the shear depicted on the models, that aspect -- the shear alone -- sounds like it's just bad luck like September 2020. Otherwise, shear had been pretty favorable until now, so it's not the same factors causing it vs. whatever other things affecting the season. (That's assuming we trust the model outputs in the first place.)

[Woofde]

So what's the red letter date for identifying something is actually odd with this season? Sept 10th? 30th? 1st? I'm not talking storm numbers, I think numbers are silly, but identifying an overall unexpected seasonal issue that is preventing development?

Mine is the Sept 10th. If we're still waiting for the models to show something on the 10th with no activity then there's clearly an unidentified issue that we should be able to learn from. If it picks up and we end up having normal to above normal then while we might bemoan a busted forecast I don't know if there's much to learn, other than seasonal variability can screw with any forecast.

I think we're already at a point where things are off of where we expected them. We've gone a week without activity and now we're likely looking at another. The seasons this was supposed to compare to (2020 and 2005) only took 1 week off at max during peak season. We are probably already locked in for a minor bust (NS count and ACE missing by a small to medium amount). Forecasts were so high that I would consider an only above average season a bust.

If we do make it to September 10th without any significant activity (I'm talking hurricanes not tropical storms), it will be time to start considering a 2013 level forecast failure. I don't think that is likely, but I also would've thought 2 weeks of nothing in late August would be extremely unlikely so we shall see.

Tropical activity doesn’t reference a calendar hanging on a wall. Just too much hand wringing far too early. IMO of course.

Tropical activity may not reference a calculator, but the Earth's tilt does. Any given season only has so many weeks of warm waters and favorable upper air conditions. Every week of peak season without storms greatly reduces the cap of what can happen. 200+ ACE can't happen overnight.

I'm still not ruling out a season that goes later than the usual and we end solidly hyperactive. It's just that there is a point where time starts to run out.

That's specifically for a season wide perspective though. From a human perspective it obviously only takes one hurricane, and we have to wait till December for that to be over.

[Hammy]

GFS shows a wavebreaking-induced TUTT by Shanshan obliterating the second wave coming off and seems to persist to the peak of the season around September 10 or so. Clearly something is not right at this point with this season.

I think after this season is done (if it continues at the rate it’s currently doing, which is certainly a good likelihood - hyperactivity is practically out of the question now), some agencies are going to take a big hit for the very high numbers predicted at the start of the season. Clearly something has changed within the atmosphere since late July that’s caused the Atlantic to become hostile for any development. I think this seems like a variation of some of 2013’s problems but different and with some elements of 2022’s issues as well - instead of getting stuck in a spring-like pattern throughout peak season, it seems as though 2024 seems to have gotten stuck in some sort of quasi-late-July pattern and has not advanced since. It also seems like the ENSO may also be a factor, as I’ve read that the pattern resembles a more Nino-like pattern, which is notable due to the fact the EPac activity resembles a Nino-like pattern, despite being only in neutral. I could be wrong with these causes but these are just my two cents for this.

The result of this was cooling in late spring and early summer over the north Atlantic--were that the case this year, the pattern would likely be replicated, and a winter-spring like atmosphere would return--it wouldn't simply get stuck in whatever season it occurred. The SSTs couldn't look more different than the months following this event than they do now.

2022 may not be dissimilar though--while the cold pool from 2022 is not present this year, the regions surrounding it are quite a bit above normal in comparison, creating a similar relative difference

[Hurricane2022]

"Spring-like pattern"
"Cooling"
"Some variation of 2013 and 2022 problems"
"Warm pool in Subtropics"
"2014"


Just relax. Keep calm and drink some beer. The activity will pickup soon, even if this busy moment becomes similar to the WPAC burst - 8/4/3 so far - and just some ACE points (~60 now).

As it looks like we're getting out of the August lull, MPI is ready to go with most of the tropical Atlantic now being cat 5 ready. Most of the WCar/Gulf also has an MPI below 900 mb. Shear across almost the entirety of the MDR is also favorable. There are of course other factors at play as well (otherwise we wouldn't have had the lack of activity so far), but shear and MPI seem to favor development right now.

https://i.imgur.com/DvoSEL1.png

https://i.imgur.com/E1I4yL4.gif

[Hammy]

"Spring-like pattern"
"Cooling"
"Some variation of 2013 and 2022 problems"
"Warm pool in Subtropics"
"2014"


Just relax. Keep calm and drink some beer. The activity will pickup soon, even if this busy moment becomes similar to the WPAC burst - 8/4/3 so far - and just some ACE points (~60 now).

If this was directed at my post you're missing your mark--my point was to show what 2013 looked like, because the repeated claims that the same thing is happening this year, or that this year is in any way similar, is beyond absurd as much as the reasons behind 2013 have been discussed.

Some NHC and NOAA mets have brought up 2022 though regarding this, compared to the anomalies to the north and south, could be adding dry air (which is only a factor because of how far north the monsoon is) and likely a factor as to why we haven't seen storms form at that latitude



But you have to admit, it's not look great for the high ACE forecasts when it's four days from September and we're still saying just wait a little longer

The CFS still shows an active late September/October, but it's pushed back the switch flip it's been showing since July to September 19

[al78]

I think after this season is done (if it continues at the rate it’s currently doing, which is certainly a good likelihood - hyperactivity is practically out of the question now), some agencies are going to take a big hit for the very high numbers predicted at the start of the season.

This is why the Tropical Storm Risk forecast documents now contain more qualitative discussion about the anticipated large scale climate factors AND uncertainties in the forecasts of these and unpredictable intra-seasonal factors. To quote from the August forecast document:

"Intra-seasonal factors: Other factors which are impossible to predict such as the strength and frequency of Saharan air outbreaks, and the frequency of tropical upper tropospheric troughs (TUTT) across the tropical Atlantic (both of which inhibit hurricane activity) are not accounted for. For example, in 2013, large scale climate factors were implying an active season; however, widespread subsidence and dry air across the tropical Atlantic, which was unpredictable, countered these otherwise favourable factors. In addition, even in the absence of significant intra-seasonal factors, for a given set of climate factors, a spread in hurricane activity levels can still ensue."

There are always people that focus entirely on the numbers, ignoring the uncertainty and discussion/caveats, and go "hahaha you got it badly wrong", which may be getting more likely with this anti-intellectualism world we now live in, but whatever, ultimately it is a good idea to look at the full picture and judge on that, not a subset of it.

[dexterlabio]

"Spring-like pattern"
"Cooling"
"Some variation of 2013 and 2022 problems"
"Warm pool in Subtropics"
"2014"


Just relax. Keep calm and drink some beer. The activity will pickup soon, even if this busy moment becomes similar to the WPAC burst - 8/4/3 so far - and just some ACE points (~60 now).

As it looks like we're getting out of the August lull, MPI is ready to go with most of the tropical Atlantic now being cat 5 ready. Most of the WCar/Gulf also has an MPI below 900 mb. Shear across almost the entirety of the MDR is also favorable. There are of course other factors at play as well (otherwise we wouldn't have had the lack of activity so far), but shear and MPI seem to favor development right now.

https://i.imgur.com/DvoSEL1.png

https://i.imgur.com/E1I4yL4.gif

The switch has flipped in the wrong basin, apparently.

[Hurricane2022]

"Spring-like pattern"
"Cooling"
"Some variation of 2013 and 2022 problems"
"Warm pool in Subtropics"
"2014"


Just relax. Keep calm and drink some beer. The activity will pickup soon, even if this busy moment becomes similar to the WPAC burst - 8/4/3 so far - and just some ACE points (~60 now).

If this was directed at my post you're missing your mark--my point was to show what 2013 looked like, because the repeated claims that the same thing is happening this year, or that this year is in any way similar, is beyond absurd as much as the reasons behind 2013 have been discussed.

Some NHC and NOAA mets have brought up 2022 though regarding this, compared to the anomalies to the north and south, could be adding dry air (which is only a factor because of how far north the monsoon is) and likely a factor as to why we haven't seen storms form at that latitude

https://i.imgur.com/PcCUbIw.png

But you have to admit, it's not look great for the high ACE forecasts when it's four days from September and we're still saying just wait a little longer

The CFS still shows an active late September/October, but it's pushed back the switch flip it's been showing since July to September 19

oh, sorry

[toad strangler]

I think after this season is done (if it continues at the rate it’s currently doing, which is certainly a good likelihood - hyperactivity is practically out of the question now), some agencies are going to take a big hit for the very high numbers predicted at the start of the season.

This is why the Tropical Storm Risk forecast documents now contain more qualitative discussion about the anticipated large scale climate factors AND uncertainties in the forecasts of these and unpredictable intra-seasonal factors. To quote from the August forecast document:

"Intra-seasonal factors: Other factors which are impossible to predict such as the strength and frequency of Saharan air outbreaks, and the frequency of tropical upper tropospheric troughs (TUTT) across the tropical Atlantic (both of which inhibit hurricane activity) are not accounted for. For example, in 2013, large scale climate factors were implying an active season; however, widespread subsidence and dry air across the tropical Atlantic, which was unpredictable, countered these otherwise favourable factors. In addition, even in the absence of significant intra-seasonal factors, for a given set of climate factors, a spread in hurricane activity levels can still ensue."

There are always people that focus entirely on the numbers, ignoring the uncertainty and discussion/caveats, and go "hahaha you got it badly wrong", which may be getting more likely with this anti-intellectualism world we now live in, but whatever, ultimately it is a good idea to look at the full picture and judge on that, not a subset of it.

This made me think about one of the mets I like to read content on the regular in Michael Lowry. He was recently talking about how individual tropical seasons are usually made up of "fits and starts". As opposed to activity fitting neatly into climatological normal smoothed out by years of averages. He made an analogy that was set up probably for those who aren't fully invested in this. In that basketball, football, etc games are usually not decided on in the first quarter or the first half. No matter how good or bad a team looks. It's the final score that is the only score that matters. This season could still go on the way it is, with these unpredictable factors you mention thwarting what seemingly was set up to be a colossal Atlantic Basin season. But we are still early in the first half.

[Spacecoast]

Today’s Euro Weeklies could be nicknamed “A Tale of Two Seasons”:
- Weeks 1-3 (9/2-22): remain only at ~50% of climo overall. These haven’t changed much for days other than a gradual decline.

- Week 4 (9/23-29/new week “on the block”): the first forecast for that week is for 120% of climo and it follows the prior week’s modest 70%. So, it’s seeing some kind of sudden change. If it were a reversion to climo, it would be only at 100%, not 120%. Also, this is the first time there has been any week at 120%+ since the 8/16 run. Will be interesting to follow.
Any thoughts?

Larry,
The way I interpret these weeklies is there is a +/-20% margin of error.
In other words, if the range is between 0.8-1.2, it is deemed statistically insignificant. Hence the shaded area lights up only when there is a significant deviation from 20 year climate.

Weeks 1-3 forecasts of 0.4,0.5, & 0.7 are significant deviations from climate (especially week 1), whereas week 4 should be considered 'normal' climo. (or within the MoE).

A +/- 20% Margin of Error may seem high, but we are are talking about a forecast 648-816 hours out, so expectations of accuracy should kept in check.
I give ECMWF credit for highlighting this, and applying the Wilcoxon-Mann-Whitney (WMW) test of significance.

[psyclone]

I'm starting to think something might be off and the seasonal forecasting brain trust industrial complex could take a category 5 credibility hit. That's what makes the weather interesting and fun. Maybe as we get into fall and upper levels cool we can get some instability and some storms. In the meantime...not worrying about a monster storm system is a luxury I definitely did not anticipate. I guess we don't know what we don't know...but there's a lot of missing pieces..

[Teban54]

 https://x.com/WxTca/status/1828829025009295584



 https://x.com/MichaelRLowry/status/1828844546089738541