2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

[Shell Mound]

https://cyclonicwx.com/data/sst/crw_ssta_global.png

Well, looks like the Atlantic was listening to all of us mock it for its cool MDR and is trying to show something a *bit* different

Here's a closer look at what is going on with the MDR:

https://coralreefwatch.noaa.gov/data_current/5km/v3.1_op/daily/png/ct5km_ssta_v3.1_nwel_current.png

The warming has already stopped and cooling has resumed, according to the latest CDAS data. Additionally, the ongoing WWB is expected to be short-lived and migrate westward, so it is related to the CCKW/MJO passage rather than the ASW. So far there are absolutely no indicators of a substantial long-term warmup, and even the ASW will be insufficient to totally negate the -AMM signature and Atlantic Niño. We will need to see significant, sustained, continuous low-level westerlies to ensure a hyperactive Atlantic season that meets CSU’s call for ACE of ≥ 150. At this point ACE of ≤ 130 seems most plausible.

The MDR is still warming, at least for now.
3 day change in SST:
https://cdn.discordapp.com/attachments/289981599448039425/855128039180468226/oisst_diff_3d_tropatl_2021061600.png

Really, there's more to activity than a 1C difference in sea surface profile, 2+ months before peak season. For Gulf and Caribbean systems SST is almost never an inhibiting factor. A very active WAM, below avg shear, and favorable velocities through ASO look to have a much more profound impact. We might see not see a hyperactive season per se, but above average looks very likely.

I was referring to CSU’s forecast for an ACE of ≥ 150. As of now, actual ACE looks to be far lower. We could still see an above-average season, certainly, but only slightly above average, comparable to 2018–19, in terms of ACE. Given that ENSO looks to be ending up warmer than forecast in the short term, particularly in Niño 1+2, it raises the possibility that VWS and suppression over the Caribbean and MDR may be stronger than expected during ASO. Currently, moreover, the MDR is much cooler than the global tropics and shows no sign of changing significantly any time soon:

[JetFuel_SE]

The warming has already stopped and cooling has resumed, according to the latest CDAS data. Additionally, the ongoing WWB is expected to be short-lived and migrate westward, so it is related to the CCKW/MJO passage rather than the ASW. So far there are absolutely no indicators of a substantial long-term warmup, and even the ASW will be insufficient to totally negate the -AMM signature and Atlantic Niño. We will need to see significant, sustained, continuous low-level westerlies to ensure a hyperactive Atlantic season that meets CSU’s call for ACE of ≥ 150. At this point ACE of ≤ 130 seems most plausible.

The MDR is still warming, at least for now.
3 day change in SST:
https://cdn.discordapp.com/attachments/289981599448039425/855128039180468226/oisst_diff_3d_tropatl_2021061600.png

Really, there's more to activity than a 1C difference in sea surface profile, 2+ months before peak season. For Gulf and Caribbean systems SST is almost never an inhibiting factor. A very active WAM, below avg shear, and favorable velocities through ASO look to have a much more profound impact. We might see not see a hyperactive season per se, but above average looks very likely.

I was referring to CSU’s forecast for an ACE of ≥ 150. As of now, actual ACE looks to be far lower. We could still see an above-average season, certainly, but only slightly above average, comparable to 2018–19, in terms of ACE. Given that ENSO looks to be ending up warmer than forecast in the short term, particularly in Niño 1+2, it raises the possibility that VWS and suppression over the Caribbean and MDR may be stronger than expected during ASO. Currently, moreover, the MDR is much cooler than the global tropics and shows no sign of changing significantly any time soon:

https://i.postimg.cc/tJwhqtJG/2021-MDRGT-1.png

Do you never learn? CDAS has a massive cold bias, especially when there's a SAL outbreak.


CDAS:


CRW:


OISSTv2.1:


This is another reason why that specific CDAS is bad, it's comparing the MDR (10°N to 20°N) to the global tropics (defined as 10°S to 10°N in that graphic).

[Shell Mound]

The MDR is still warming, at least for now.
3 day change in SST:
https://cdn.discordapp.com/attachments/289981599448039425/855128039180468226/oisst_diff_3d_tropatl_2021061600.png

Really, there's more to activity than a 1C difference in sea surface profile, 2+ months before peak season. For Gulf and Caribbean systems SST is almost never an inhibiting factor. A very active WAM, below avg shear, and favorable velocities through ASO look to have a much more profound impact. We might see not see a hyperactive season per se, but above average looks very likely.

I was referring to CSU’s forecast for an ACE of ≥ 150. As of now, actual ACE looks to be far lower. We could still see an above-average season, certainly, but only slightly above average, comparable to 2018–19, in terms of ACE. Given that ENSO looks to be ending up warmer than forecast in the short term, particularly in Niño 1+2, it raises the possibility that VWS and suppression over the Caribbean and MDR may be stronger than expected during ASO. Currently, moreover, the MDR is much cooler than the global tropics and shows no sign of changing significantly any time soon:

https://i.postimg.cc/tJwhqtJG/2021-MDRGT-1.png

Do you never learn? CDAS has a massive cold bias, especially when there's a SAL outbreak.
https://cdn.discordapp.com/attachments/848666910790909983/856076981401681920/g16split.jpg

CDAS:
https://cdn.discordapp.com/attachments/484125418727800843/856082232036294686/mdrssta.png

CRW:
https://cdn.discordapp.com/attachments/484125418727800843/856079168893878282/crw_ssta_graph_atlmdr.png

OISSTv2.1:
https://cdn.discordapp.com/attachments/484125418727800843/856079258362708028/ssta_graph_atlmdr.png

This is another reason why that specific CDAS is bad, it's comparing the MDR (10°N to 20°N) to the global tropics (defined as 10°S to 10°N in that graphic).

You are correct. I shall no longer rely on CDAS during SAL outbreaks and easterly trade surges. Also, I shall heed your point about the MDR vs. the global tropics.

[jconsor]

Disagreement between the CFS and EPS/JMA for Jul.

 https://twitter.com/yconsor/status/1406653716313382914

[Shell Mound]

This will definitely decrease the odds of an active season if it verifies, given that it implies an inactive MDR during July, which correlates negatively with ACE:

 https://twitter.com/webberweather/status/1406635328765521921



 https://twitter.com/webberweather/status/1406636710130196489



 https://twitter.com/AndyHazelton/status/1406642802889461768



 https://twitter.com/webberweather/status/1406656868412395522




Incidentally, a less active peak season in the deep tropics would also decrease the risk of a Cat-4+ hit on the U.S., given a less active MDR/Caribbean.

[jconsor]

 https://twitter.com/yconsor/status/1406611188104978434

[Hammy]

https://twitter.com/yconsor/status/1406611188104978434

This seems like a significant change over the last three seasons.

[Kingarabian]

This will definitely decrease the odds of an active season if it verifies, given that it implies an inactive MDR during July, which correlates negatively with ACE:

https://twitter.com/webberweather/status/1406635328765521921
https://twitter.com/webberweather/status/1406636710130196489
https://twitter.com/AndyHazelton/status/1406642802889461768
https://twitter.com/webberweather/status/1406656868412395522

Incidentally, a less active peak season in the deep tropics would also decrease the risk of a Cat-4+ hit on the U.S., given a less active MDR/Caribbean.

Nino 1+2 warming is also playing a role in this above average shear forecast from the CFS for July.

[Yellow Evan]

CFS has been trying to dissipate the ASW for years and it's almost always been wrong.

[cycloneye]

The counter by Blake.

 https://twitter.com/EricBlake12/status/1406708269121425409

[Kingarabian]

I don't think the ASW will vanish like the CFS is trying to show, but it might have competition since there has been some sort of standing wave near 150E/160E for a while now.


There remains a good amount of warm subsurface anomalies beneath the Nino regions that are beginning to surface. This is probably throwing some of the modeling off as well.

[Yellow Evan]

I don't think the ASW will vanish like the CFS is trying to show, but it might have competition since there has been some sort of standing wave near 150E/160E for a while now.
https://i.imgur.com/UNxgcLo.png

There remains a good amount of warm subsurface anomalies beneath the Nino regions that are beginning to surface. This is probably throwing some of the modeling off as well.

 https://twitter.com/cyclonicwx/status/1406714982931238912

[Kingarabian]

I don't think the ASW will vanish like the CFS is trying to show, but it might have competition since there has been some sort of standing wave near 150E/160E for a while now.
https://i.imgur.com/UNxgcLo.png

There remains a good amount of warm subsurface anomalies beneath the Nino regions that are beginning to surface. This is probably throwing some of the modeling off as well.

[url]https://twitter.com/cyclonicwx/status/1406714982931238912?s=21[url]

Maybe we need to wait till the end of July to have a full 90 day average to see what's going on. Even in that graphic, from April 16-May18 forcing over Africa was the strongest globally. But from May18-June17 whatever that is near 150E/160E, the forcing there was just as strong. Looks like we have two persistent areas this year. But seeing that ENSO will likely flip to negative, the ASW should be favored.

[cycloneye]

Keep these very knowlegable and interesting discussions going about what is and may go on in the next few weeks.

[aspen]

2020’s seasonal indicators seem straightforward compared to all of this. Competing rising branches, different ENSO regions warmer/cooler than the other, models flip-flopping from an active setup to a much weaker ASW/Africa-IO rising branch, debate over how favorable the SST setup is and will be, etc. Seems like every week there’s something new that could potentially cause 2021 to abruptly become an unfavorable (or not as favorable) season for TC activity.

[toad strangler]

2020’s seasonal indicators seem straightforward compared to all of this. Competing rising branches, different ENSO regions warmer/cooler than the other, models flip-flopping from an active setup to a much weaker ASW/Africa-IO rising branch, debate over how favorable the SST setup is and will be, etc. Seems like every week there’s something new that could potentially cause 2021 to abruptly become an unfavorable (or not as favorable) season for TC activity.

No different than any other year IMO. The same conversations went on last year in regards to SST's, SAL, Shear, etc as they do every year regardless of the outlooks that the professionals produce. Meanwhile, what IS actually happening early on, is pretty darn active. So I'm leaning towards the pro seasonal product output right now while gleaning what I can from place like this that can be so good many times. Every year it gets a bit easier to sift through the gray matter. We'll see!

[aspen]

2020’s seasonal indicators seem straightforward compared to all of this. Competing rising branches, different ENSO regions warmer/cooler than the other, models flip-flopping from an active setup to a much weaker ASW/Africa-IO rising branch, debate over how favorable the SST setup is and will be, etc. Seems like every week there’s something new that could potentially cause 2021 to abruptly become an unfavorable (or not as favorable) season for TC activity.

No different than any other year IMO. The same conversations went on last year in regards to SST's, SAL, Shear, etc as they do every year regardless of the outlooks that the professionals produce. Meanwhile, what IS actually happening early on, is pretty darn active. So I'm leaning towards the pro seasonal product output right now while gleaning what I can from place like this that can be so good many times. Every year it gets a bit easier to sift through the gray matter. We'll see!

Well, this is only my second year monitoring the tropics throughout the entire pre-season and season, and I’m not a pro met, so many of these seasonal indicators are still confusing to varying degrees. They’ll get somewhat easier to understand the more seasons I monitor with everyone else here.

[Ubuntwo]

Moderate MDR/Caribbean warming continues. Some cooling in the Gulf from pre-Claudette.

[tolakram]

2021 doesn’t need to have a super early MDR hurricane like Beryl, but last year I went through every season from 1980 to present day and found a strong correlation between MDR or AEW-based storms/hurricanes in July and overall season activity. Accounting for 2020 (which had 3 AEW July systems, two of which became hurricanes), the average season numbers are:
—16.9 named storms
—9.0 hurricanes
—4.1 majors
—160.29 ACE

For seasons that had any non-AEW-based July system, even if they also had a tropical wave born system as well, the average is much lower:
—13.4 named storms
—6.6 hurricanes
—2.9 majors
—115.40 ACE

So yes, July activity is a very strong sign of what the rest of the season could be like. However, the fact that a lot of things are attempting to form this early does make the predictions for an above-average season more likely…unless there’s a sudden shift to +ENSO.

Bringing this over here, since it was used as a source.

This article also says an Active July portends a higher ACE season.

https://www.wunderground.com/cat6/farewell-don-watching-hilary

2017 ended up at 226 ACE after 2.5 systems in July.

What this doesn't say is the typical ACE for seasons with lower July activity.

[CyclonicFury]

2021 doesn’t need to have a super early MDR hurricane like Beryl, but last year I went through every season from 1980 to present day and found a strong correlation between MDR or AEW-based storms/hurricanes in July and overall season activity. Accounting for 2020 (which had 3 AEW July systems, two of which became hurricanes), the average season numbers are:
—16.9 named storms
—9.0 hurricanes
—4.1 majors
—160.29 ACE

For seasons that had any non-AEW-based July system, even if they also had a tropical wave born system as well, the average is much lower:
—13.4 named storms
—6.6 hurricanes
—2.9 majors
—115.40 ACE

So yes, July activity is a very strong sign of what the rest of the season could be like. However, the fact that a lot of things are attempting to form this early does make the predictions for an above-average season more likely…unless there’s a sudden shift to +ENSO.

Bringing this over here, since it was used as a source.

This article also says an Active July portends a higher ACE season.

https://www.wunderground.com/cat6/farewell-don-watching-hilary

2017 ended up at 226 ACE after 2.5 systems in July.

What this doesn't say is the typical ACE for seasons with lower July activity.

I believe 2017 only had about 1 ACE in July. 2004 had 0. You don't always need an active June or July for a strong hurricane season. I think it's possible we could see a hurricane in July, but you don't see one every year.