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

[AnnularCane]

Is neutral more favorable than La Nina?

[Teban54]

Is neutral more favorable than La Nina?

I think there were extensive discussions of this last year, when almost everyone expected a La Nina, possibly a strong one. You can refer to the 2024 thread, but my vague recollection (which can jolly well be wrong) is:

• ENSO generally doesn't really hinder activity unless it's warm neutral or warmer.
• Strength of La Nina is correlated with tracks more often than with levels of activity. Cool neutral and weak La Ninas are often associated with greater US threats (as seen from last year), while stronger La Ninas often end up affecting the Caribbean more instead.
• However, any correlations are weak (compared to the combination of all other factors), and not necessarily causal.

[WaveBreaking]

Unrelated to ENSO, but the cool pool in the Central Atlantic has been warming while the MDR and far North Atlantic have been cooling despite the strong -NAO in place. Essentially a weakening of the +++AMO the Atlantic’s been in since 2023. The seasonal models show a warm blob taking the place of the current cool blob, which would suggest instability issues for the MDR.

[cycloneye]

Unrelated to ENSO, but the cool pool in the Central Atlantic has been warming while the MDR and far North Atlantic have been cooling despite the strong -NAO in place. Essentially a weakening of the +++AMO the Atlantic’s been in since 2023. The seasonal models show a warm blob taking the place of the current cool blob, which would suggest instability issues for the MDR.

https://i.imgur.com/nU3Zwff.gif
https://i.imgur.com/NAe18Lr.png

The gulf is the warmest part of the basin right now but Caribbean Sea is warm beneath the surface.

[Long John]

Unrelated to ENSO, but the cool pool in the Central Atlantic has been warming while the MDR and far North Atlantic have been cooling despite the strong -NAO in place. Essentially a weakening of the +++AMO the Atlantic’s been in since 2023. The seasonal models show a warm blob taking the place of the current cool blob, which would suggest instability issues for the MDR.

https://i.imgur.com/nU3Zwff.gif
https://i.imgur.com/NAe18Lr.png

We are not in a strong -NAO; in fact, we are barely even in -NAO

[WaveBreaking]

Unrelated to ENSO, but the cool pool in the Central Atlantic has been warming while the MDR and far North Atlantic have been cooling despite the strong -NAO in place. Essentially a weakening of the +++AMO the Atlantic’s been in since 2023. The seasonal models show a warm blob taking the place of the current cool blob, which would suggest instability issues for the MDR.

https://i.imgur.com/nU3Zwff.gif
https://i.imgur.com/NAe18Lr.png

We are not in a strong -NAO; in fact, we are barely even in -NAO

I feel like the only reason the -NAO isn’t appearing to be as strong is due to it being west-based. And ignore what I said about the NAO anyways since I forgot that it was positive from late January into the first half of February.

[Long John]

Unrelated to ENSO, but the cool pool in the Central Atlantic has been warming while the MDR and far North Atlantic have been cooling despite the strong -NAO in place. Essentially a weakening of the +++AMO the Atlantic’s been in since 2023. The seasonal models show a warm blob taking the place of the current cool blob, which would suggest instability issues for the MDR.

https://i.imgur.com/nU3Zwff.gif
https://i.imgur.com/NAe18Lr.png

We are not in a strong -NAO; in fact, we are barely even in -NAO

I feel like the only reason the -NAO isn’t appearing to be as strong is due to it being west-based. And ignore what I said about the NAO anyways since I forgot that it was positive from late January into the first half of February.

https://i.imgur.com/wBP7Ggn.png

https://www.cpc.ncep.noaa.gov/products/ ... .sprd2.png

[cycloneye]

We will see how the sst's be in the comming months, but right now the MDR is not warm and then come those two words "is early".

[USTropics]

100 day countdown until the official start of hurricane season is upon us! It's a bit too early to start looking at climate models for peak season with any reasonable degree of certainty, but I do think the models are starting to agree on what we should expect in April/May. Here is a quick roundup of the top 3 climate models for SSTA and May:

NMME


CanSIPS


CFS


What the models agree on for the North Atlantic at this point for May:

Polar jet stream continues to flex through spring
This doesn't exactly come as surprise given the current state of the atmosphere (i.e., heavy leaning La Nina over CONUS, even if the ENSO index doesn't represent this given the background state). During La Nina, the polar jet stream tends to position itself over the NE CONUS during late winter/early spring. Those cold anomalies off the northeast coast are a dead giveaway we are likely to continue to see a parade of mid-latitude systems through at least April.


MDR features neutral/slight warm anomalies
As cycloneye posted above, the MDR doesn't have a giant head start on warm anomalies this season as it did last year. Here is the configuration from last year:


Compared to this year:


Subtropics are cooking
While you would think cold anomalies off the northeast coast would lead to some cooling of the subtropics, this region is dominantly driven by wind shear anomalies. Since there is sort of a lag effect here, let's take a look at zonal wind anomalies from April:


We can see significantly reduced zonal winds over the subtropics, and this is leading to the +warm anomalies in the subtropics and more neutral anomalies over the MDR.

Upwelling along the western African coast
Also in the in zonal wind anomalies above, you can see this red/orange tongue over the coast of Africa in April (enhanced trade winds). This is the primary driver of upwelling along the western coast of Africa.

Atlantic 'La Nina'
Off the map a bit, but there are hints of an Atlantic Nina developing by April/May. In combination with the coastal upwelling off of Africa, this may hinder MDR warmth propagation through May/June.



Again, this is just looking at some of the precursors for hurricane season in May and not a forecast for hurricane season. There are mixed signals currently on the climate models with MDR anomalies and Atlantic configuration in ASO, but I would currently hedge towards a +warm subtropical anomaly configuration. Let's see how this progresses through the spring predictability barrier and reevaluate in April.

[DorkyMcDorkface]

100 day countdown until the official start of hurricane season is upon us! It's a bit too early to start looking at climate models for peak season with any reasonable degree of certainty, but I do think the models are starting to agree on what we should expect in April/May. Here is a quick roundup of the top 3 climate models for SSTA and May:

NMME
https://i.imgur.com/kpYBy8O.png

CanSIPS
https://i.imgur.com/TnI6PmB.png

CFS
https://i.imgur.com/umdHxCH.png

What the models agree on for the North Atlantic at this point for May:

Polar jet stream continues to flex through spring
This doesn't exactly come as surprise given the current state of the atmosphere (i.e., heavy leaning La Nina over CONUS, even if the ENSO index doesn't represent this given the background state). During La Nina, the polar jet stream tends to position itself over the NE CONUS during late winter/early spring. Those cold anomalies off the northeast coast are a dead giveaway we are likely to continue to see a parade of mid-latitude systems through at least April.
https://i.imgur.com/mNdcGSv.png

MDR features neutral/slight warm anomalies
As cycloneye posted above, the MDR doesn't have a giant head start on warm anomalies this season as it did last year. Here is the configuration from last year:
https://i.imgur.com/CjSIXYM.png

Compared to this year:
https://i.imgur.com/AENx1EP.png

Subtropics are cooking
While you would think cold anomalies off the northeast coast would lead to some cooling of the subtropics, this region is dominantly driven by wind shear anomalies. Since there is sort of a lag effect here, let's take a look at zonal wind anomalies from April:
https://i.imgur.com/r3qX2Mi.png

We can see significantly reduced zonal winds over the subtropics, and this is leading to the +warm anomalies in the subtropics and more neutral anomalies over the MDR.

Upwelling along the western African coast
Also in the in zonal wind anomalies above, you can see this red/orange tongue over the coast of Africa in April (enhanced trade winds). This is the primary driver of upwelling along the western coast of Africa.

Atlantic 'La Nina'
Off the map a bit, but there are hints of an Atlantic Nina developing by April/May. In combination with the coastal upwelling off of Africa, this may hinder MDR warmth propagation through May/June.
https://i.imgur.com/noxQlNj.png


Again, this is just looking at some of the precursors for hurricane season in May and not a forecast for hurricane season. There are mixed signals currently on the climate models with MDR anomalies and Atlantic configuration in ASO, but I would currently hedge towards a +warm subtropical anomaly configuration. Let's see how this progresses through the spring predictability barrier and reevaluate in April.

Appreciate the analysis...as it stands right now it seems the general seasonal indicators aren't quite as favorable looking as they were around this time last year, but then again I'd imagine it'd be pretty difficult to replicate the +++AMO signature we saw in the Atlantic last year

[cycloneye]

The countdown for the upcomming 2025 season is on with 99 days left, so let's turn active this and other threads in this talking tropics forum.

https://www.timeanddate.com/countdown/g ... sive&csz=1

[Category5Kaiju]

I do think that coming out of two years with unnaturally warm (if not record-breaking) MDR warmth has kind of spoiled us. What we're seeing now, with a rather lukewarm MDR at this point of the year, is more "normal," sorta speak.

But also some food for thought. Here's 2017, at around this point in time.



While in no way am I saying that I expect 2025 to be like 2017, I do think that 2017 may not be a terrible analog year for this year, considering how 2016/2024 were heavily backloaded and active La Nina years, as well as how 2017 and what is likely to occur later this year may witness a double dip -ENSO event. But notably, just by looking at 2017's ssta map at this point in the year, you probably would've never imagined the season to end up as a +220 ACE one with multiple Category 5 hurricanes and 10 hurricanes in a row. And, guess what? This year ended up more active than 2024. Just really shows how MDR warmth is a key factor, but not the entire picture.

[Teban54]

I do think that coming out of two years with unnaturally warm (if not record-breaking) MDR warmth has kind of spoiled us. What we're seeing now, with a rather lukewarm MDR at this point of the year, is more "normal," sorta speak.

But also some food for thought. Here's 2017, at around this point in time.

https://www.star.nesdis.noaa.gov/pub/socd/mecb/crw/data/5km/v3.1_op/image_plain/daily/ssta/png/2017/ct5km_ssta_v3.1_20170221.png

While in no way am I saying that I expect 2025 to be like 2017, I do think that 2017 may not be a terrible analog year for this year, considering how 2016/2024 were heavily backloaded and active La Nina years, as well as how 2017 and what is likely to occur later this year may witness a double dip -ENSO event. But notably, just by looking at 2017's ssta map at this point in the year, you probably would've never imagined the season to end up as a +220 ACE one with multiple Category 5 hurricanes and 10 hurricanes in a row. And, guess what? This year ended up more active than 2024. Just really shows how MDR warmth is a key factor, but not the entire picture.

This map also gives the impression of a La Nina Modoki (west-based Nina) for 2016-17, which I hadn't thought of before. Another similarity to current SSTs.

[cycloneye]

 https://x.com/cyclonicwx/status/1893493528363139572

[WaveBreaking]

There’s this inverted trough that’s patrolling the MDR rn; a sign of what’s to come.

[chaser1]

There’s this inverted trough that’s patrolling the MDR rn; a sign of what’s to come.

https://i.imgur.com/rnY413A.gif

For what it is, I'd say rather impressive for late February. That's quite some Easterly surge for this time of year

[WeatherBoy2000]

 https://x.com/cyclonicwx/status/1893493528363139572

The one notable thing different about now and pre-2023 is the lack of warmth in the western subtropics/north Atlantic:



vs now:

[cycloneye]

Still #3.

[weeniepatrol]

Still #3.

https://i.imgur.com/g7Lqq2E.jpeg

Yep. Just because we are much cooler than last year so far doesn’t mean we aren’t still well above average. Very important to not lose sight of that fact.

[WaveBreaking]

Still #3.

https://i.imgur.com/g7Lqq2E.jpeg

Crazy how the current MDR SSTs, while cooler than 2024’s, are still at the average values for May. That’s 2 months ahead of schedule. If we weren’t spoiled by 2023 and 2024’s ridiculous MDR temps, then maybe this season would be getting more attention at this point (barring exhaustion from the hyperactive season we had last year).