2025 Indicators: SST's, MSLP, Shear, SAL, Steering, Instability (Day 16+ Climate Models)

[LarryWx]

Here’s a post I made elsewhere on 9/13/24:

9/12/24 Euro Weeklies mean ACE progs (% of climo for the week) (Euro climo based on 2004-23):

9/16-22: 6 (40%)(has been BN)

9/23-29: 14 (110%)(has been NN)

9/30-10/6: 16 (170%)(has been AN)(16 is climo of peak week of 9/9-15)

10/7-13: 10 (140%)(has been AN)

- So, the week of 9/30-10/6 is forecasted by the current Weeklies to be the busiest in terms of ACE. This run is essentially predicting peak climo ACE 3 weeks late despite 9/30-10/6 climo already being down 40% from its peak!

- As the above shows along with prior runs, the Weeklies have been consistent with a BN late Aug through mid Sept, a NN late Sept, and AN 1st 2 weeks of Oct. So, these signals are rather strong.

- This is the 4th run in a row having 9/30-10/6 the busiest week.

- So, this run is predicting ACE to be ~107 as of Oct 13th. (I added a point for 9/13-5 though there may be none.)

[WeatherBoy2000]

Though 8/4-10 dropped due to no support likely partially related to little support for the current MDR AEW, the Euro Weeklies are slightly more ominous than yesterday’s for August’s ACE as a whole:

% of 2005-24 averages:
8/4-10: 80% (slightly lower than yest.)
8/11-17: 190% (slightly higher than yest.)
8/18-24: 210% (much higher than yest.)
8/25-31: 110% (same as yest)

Taken as a whole, these probably imply a prog of ~38 ACE for next month fwiw. Please don’t shoot the innocent messenger!

Not trying to shoot the messenger lol but do keep in mind these really did not do well last year. The drop inside 2 weeks but high values outside of it is a red flag. Wouldn't be surprised if next time this week we see the 8/11-17 come down too

I hope so! But unfortunately my clear recollection of last year (also I saved some of those EW progs in addition to looking back at 2024 posts) was that when the Euro Weeklies locked in either active or inactive vs climo from several weeks out that those weeks did quite well.

For example, it had many, many days in a row of active weeks forecasted for mid to late June of ‘24, which verified well. It then forecasted from several weeks out the 3 week long peak season lull accurately with well under 100% of normal on run after run after run.

Subsequently, it was spot on with consistently forecasting the near record high ACE of the 3 week long period of late Sept through mid Oct, which included some insanely high %s of normal ACE for early to middle Oct. Remember those very tall green boxes going so high that they literally went off the chart?

So, if these active mid to late Aug weeks were to maintain themselves for, say, over the next week, I’ll probably then be starting to take them seriously.

Yeah all models and forecasters failed to predict what happened during the peak the last year, it was a complete anomaly. Even if we don't see a super active peak, seeing something to the extent of 2024 again with an -enso/above normal mdr ssts is very unlikely.

[LarryWx]

Here’s a 9/3/24 post I made about the Euro Weeklies:

Today’s Euro Weeklies added a new week, Sep 30-Oct 6, and that week is quite active vs climo. In addition the week before is also progged to be active as has been the case on many runs.

So this run suggests that activity will pick up markedly next week though would still be below avg. After a similar subsequent week, activity is suggested to pick up substantially in late Sep and continue into early Oct vs climo:

9/3/24 Euro Weeklies (EW) mean ACE projections as % of climo:
9/2-8: 20% per yest.’s run (meaning ACE of 3)
9/9-15: 60% (meaning ACE of 10)(climo peak week)
9/16-22: 70% (meaning ACE of 11)
9/23-29: 130% (meaning ACE of 17)(vs peak wk climo of 16)
9/30-10/6: 140% (new week)(meaning ACE of 13)

So, today’s EW progs by week are 3-10-11-17-13 meaning two most active weeks are at the end despite climo having dropped off substantially from peak by then. That would get 2024 to ~110 ACE as of Oct 6.
——————————

Here’s a 8/26/24 EW related post from me:

Euro Weeklies are still not giving in to more active. Sunday’s had member mean of 27 ACE for the next 4 weeks vs 1991-2020 avg of 58. If relative quiet were to verify, they’d deserve major kudos for being so persistent. Regardless, they’re still calling for some activity and not anywhere near dead.

[cycloneye]

 https://x.com/BenNollWeather/status/1950934224367976808

[cycloneye]

 https://x.com/webberweather/status/1951307307523944664

[WeatherBoy2000]

 https://x.com/webberweather/status/1951438827605860369



 https://x.com/webberweather/status/1951444296986665448



 https://x.com/webberweather/status/1951448646911926442



Regardless of how active the season ends up being, this is a threatening pattern for the US as we head into the peak.

[StormWeather]

 https://x.com/webberweather/status/1951438827605860369



 https://x.com/webberweather/status/1951444296986665448



 https://x.com/webberweather/status/1951448646911926442



Regardless of how active the season ends up being, this is a threatening pattern for the US as we head into the peak.

I’m not quite sure I understand? Can you explain it?

[WeatherBoy2000]

 https://x.com/webberweather/status/1951438827605860369



 https://x.com/webberweather/status/1951444296986665448



 https://x.com/webberweather/status/1951448646911926442



Regardless of how active the season ends up being, this is a threatening pattern for the US as we head into the peak.

I’m not quite sure I understand? Can you explain it?

Andy Hazelton explains it better here:

 https://x.com/AndyHazelton/status/1951443947592532030



This pattern generally blocks storms in the western Atlantic from recurving and instead drives them into the US.

[Category5Kaiju]

I really hope not, but some of these recent analyses on the ridging pattern makes me wonder if we may be in for a high-risk season for the East Coast of the US (Florida included), something we haven't seen in a while.

[DorkyMcDorkface]

 https://x.com/MassachusettsWx/status/1951557330233163909

[cycloneye]

JB more bullish.

 https://x.com/BigJoeBastardi/status/1951674733847535995

[Cpv17]

I really hope not, but some of these recent analyses on the ridging pattern makes me wonder if we may be in for a high-risk season for the East Coast of the US (Florida included), something we haven't seen in a while.

You should definitely have included the Gulf, not just the EC. I think we should all be paying attention equally from the Caribbean, the EC, and the Gulf states.

[LarryWx]

The jury is obviously far from a decision for the overall 2025 NATL season. Yes, YTD NATL ACE has been very low (1.5 vs 1951-2024 avg of ~9) through this morning with it at 64th highest out of the last 75 seasons. And being that low this far into the season does increase the chance for a quiet rest of season somewhat, which I’d love to see for a change. And yes, there are two new areas in the EPAC that may develop this week. However:


1. The EPAC is currently still at only 28 ACE vs a normal of 47 meaning it’s now ranked at only 39 of the last 55 seasons.

2. We have weak La Ninalike conditions, which are typically conducive for an active rest of season.


3. The following other relatively quiet through now NATL seasons (under 5 ACE vs normal of 9) were active the rest of the season:



Season: Total season’s NATL ACE

1969: 148 and that was El Niño (don’t have EPAC pre-1971); only 1 storm as of now (not an H) with 17 others still to come and not til Aug 10th+

2017: 225 and EPAC was then way up at 74 (12/54); no H yet with 10 H/6 MH still to come Aug 7th+

2019: 132 and EPAC ACE was then up at 45; only 2 storms as of now with 16 more to come and not til Aug 20th+

1980: 148

1999: 176; only 1 storm through now (not an H) with 11 others to come and not til Aug 18th+ including 5 MH

2004: 227 and that was El Niño; only 2 storms through now with 13 more to come Aug 9th+ including 9H/6 MH

1998: 181 and EPAC was then up at 55 (14/54); only one storm as of now (not an H) with 13 more to come, including 10 H and not til Aug 19+

1955: 158 (don’t have EPAC pre-1971); only 2 storms through now (no H yet) with 9H/4 MH still to come

1967: 125 (don’t have EPAC pre-1971); only 1 storm as of now with 12 more to come and not til Aug 28+

From this list: 1969, 2017, 2019, 2004, and 1998 should especially get one’s attention.



4. The Euro Weeklies, which overall did well last year with its several week out predictions, have been forecasting an active August for the last 5 days.

5. The various ensemble runs have been active both in the MDR as well as off of NC. The current TWO is already highlighting two areas.

6. The MJO is headed for phases 1 and 2, two often active phases during August.

————————
Edit:  In summary, whereas the very low ACE as of this morning is typically a slightly bearish indicator the rest of the season as a whole, my points 1-6, above, suggest that an active rest of the season is at the very least still a reasonable possibility and may actually still be favored.

[ScottNAtlanta]

Looking at the wave north of PR and it foreshadows what is going to be happening for a good part of the season. Waves come off Africa looking robust with spin, they lose convection as they move west, then they get to the sweet spot where the current wave is and then they blow up. I think there is going to be a lot of those going forward.

[Keldeo1997]

 https://x.com/webberweather/status/1952535346530648315



 https://x.com/webberweather/status/1952543359257751612

[chaser1]

THAT pattern could well result in another one or more insurance companies to go belly-up!

Good segway for the next poll!
Total Number of Named Storms to Make Landfall This Year.
We're "officially" sitting at two thus far. I'll throw in right now, with 5 more (total of 7 landfalls) for the year.

[LarryWx]

For those wanting a relatively quiet season like myself, the new Euro seasonal NATL forecast is not what you want to see. It has substantially increased from the near normal of last month’s forecast, which had ~125 ACE, to today’s ~155. This is estimated by taking its 130% of normal for Sept+ and adding the 1.5 prior to Aug and its latest Weeklies forecast for Aug, which is now at ~40, well AN.

The implied total seasonal # of NS has risen from 15 to ~17-18. The # of H has risen from 6 to ~7.5.

The concentration of tracks at/near the Conus has risen from very slightly BN to AN.

[chaser1]

Whoa! What a difference a day makes? The Atlantic ITCZ seems to really be waking up with an impressive increase in convection. For that matter, the area of disturbed weather over and just east of the Eastern Bahamas is starting to catch my eye.

[Hurricane2022]

 https://x.com/webberweather/status/1952886993651941790


 https://x.com/webberweather/status/1952889571169210503

[DorkyMcDorkface]

 https://x.com/webberweather/status/1952886993651941790


 https://x.com/webberweather/status/1952889571169210503

This feels like jumping the gun, no? I know Webb has been persistently bearish on his seasonal outlook but there's been model/ensemble support for TCG in the tropical Atlantic for the first two weeks of this month for a while now. If there were nothing in the pipeline appearing on the guidance I would agree, but that's not the case.