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

[SFLcane]

https://twitter.com/ericblake12/status/1418183722713616384

I would lean towards the ECMWF. The GEFS has had serious problems with VP anomalies.

Well…, EPS blew the transition. GEFS and CFS was the only one showing the WPAC amplification.

[aspen]

The current ACE total is so high that it’ll take until August 15th or 16th to match the climatological mean on CSU, assuming no storms form between now and mid-August. That means Atlantic ACE will be either near or above-average if the EPac/TUTT shear the western Atlantic for the next 3 weeks, so when something significant does finally form, the basin will be back on track to be ahead of the norm.

A lot of Elsa’s ACE was artificially inflated past the islands, given that the NHC tended to give it higher MSW than surface + recon data suggested. (See earlier posts by wxman57 on this.) It was definitely a hurricane over the islands, but I doubt it regained hurricane status in the Gulf, and for much of its time as a “TS” it was either a low-end one or briefly an open wave. Plus, Claudette and Danny were borderline cases at best, and might not have been classified just a decade or so earlier. Therefore, I think actual ACE generation to date has been at least a bit lower than indicated.

Danny was without a doubt a TC, despite being weak and sheared and short-lived. That closed LLC was plain as day.

[Shell Mound]

https://twitter.com/ericblake12/status/1418183722713616384

I would lean towards the ECMWF. The GEFS has had serious problems with VP anomalies.

Well…, EPS blew the transition. GEFS and CFS was the only one showing the WPAC amplification.

 https://twitter.com/webberweather/status/1417907023350468610



 https://twitter.com/webberweather/status/1417856286235021317



 https://twitter.com/webberweather/status/1417858201538736130



 https://twitter.com/webberweather/status/1417861362563301377



 https://twitter.com/EricBlake12/status/1417862273432006665



 https://twitter.com/AndyHazelton/status/1417864202715291648



 https://twitter.com/webberweather/status/1417924453078638592

[cycloneye]

The battle between the models rages on.

 https://twitter.com/AndyHazelton/status/1418190117529870346




 https://twitter.com/cyclonicwx/status/1418190574558007301

[AlphaToOmega]

The battle between the models rages on.

https://twitter.com/AndyHazelton/status/1418190117529870346

https://twitter.com/cyclonicwx/status/1418190574558007301

Euro: Atlantic; Pacific
GEFS: Pacific; Atlantic
JMA: Atlantic; Pacific

This is our climate model consensus.

[Category5Kaiju]

I wonder when the last season was that these models had such enormous disagreements, oh man

[Teban54]

So it seems like according to the models, the expected return of favorable conditions have been pushed back from late July to early August and now to mid August?

Not trying to cancel the season - I've always expected nothing to form before August 20 in most seasons - but I do wonder if such "trends" in model forecasts will continue, or will they stop just in time for the peak season.

[AlphaToOmega]

So it seems like according to the models, the expected return of favorable conditions have been pushed back from late July to early August and now to mid August?

Not trying to cancel the season - I've always expected nothing to form before August 20 in most seasons - but I do wonder if such "trends" in model forecasts will continue, or will they stop just in time for the peak season.

Only one model is pushing it back to mid-August. The others still thing late July is when favorable conditions will return.

[Category5Kaiju]

So it seems like according to the models, the expected return of favorable conditions have been pushed back from late July to early August and now to mid August?

Not trying to cancel the season - I've always expected nothing to form before August 20 in most seasons - but I do wonder if such "trends" in model forecasts will continue, or will they stop just in time for the peak season.

The fact that we’re highly likely about to enter a La Niña phase again soon and the fact that we already had 5 storms, with one MDR hurricane in July (something only 6 other recorded years have had, all of which became hyperactive) make me want to believe otherwise. I cannot imagine why the Atlantic would not be the NH favored season come ASO in this kind of year, I think the signals are there and strong enough. Maybe not a 30 NS season like last year, but active seems likely imho

[AlphaToOmega]

The season is just like 2017 in terms of lulls and bursts of activity. The first burst of activity this season, there were four storms (Bill, Claudette, Danny, and Elsa). The first of activity in 2017, there were two storms (Bret and Cindy). Therefore, the background state of 2021 is twice as favorable as the background state of 2017. 2017 had 17 storms, 10 hurricanes, and 6 major hurricanes. If the background state really is twice as favorable as 2017, we would have 34 storms, 20 hurricanes, and 12 major hurricanes this season.

[SFLcane]

I still think 10th-20th sometime the Atlantic becomes prime for development.

[Category5Kaiju]

The season is just like 2017 in terms of lulls and bursts of activity. The first burst of activity this season, there were four storms (Bill, Claudette, Danny, and Elsa). The first of activity in 2017, there were two storms (Bret and Cindy). Therefore, the background state of 2021 is twice as favorable as the background state of 2017. 2017 had 17 storms, 10 hurricanes, and 6 major hurricanes. If the background state really is twice as favorable as 2017, we would have 34 storms, 20 hurricanes, and 12 major hurricanes this season.

While I would agree that the overall background state is decently favorable and that 2017 is a great example of an active season that suddenly came to life in late August, I am not sure if a 34/20/12 season is realistic for the Atlantic. Maybe the WPAC, but I personally think (and this is based on a pretty small sample size), but if you were to have a season with a storm count in the high 20s or low 30s at least, then we should be at the J storm or so by early next month. I think a 20 NS count total (or maybe slightly more or less) is still very plausible, and don't get me wrong, a 20 NS season would be the third most active Atlantic season recorded if it verifies.

[jconsor]

W Pacific TC activity has a significant suppressive influence on favorability for TC activity in the Carib and W. Atlantic, but less influence in the eastern Atlantic.

 https://twitter.com/yconsor/status/1418208498102333445




 https://twitter.com/AndyHazelton/status/1418204793588224003

[aspen]

I still think 10th-20th sometime the Atlantic becomes prime for development.

I agree that’ll be the start of peak favorability in the Atlantic, but I still think we’ll get a substantial system
— at least a strong TS from an AEW — in the next 2-3 weeks. August 1-10th would just be the warm-up, depending on which model wins out.

[Shell Mound]

Source

[jconsor]

MH landfalls are too infrequent (especially since 1950s) to gauge much correlation. I'll try to look for hurricane landfalls or cat 2+ landfalls and see if there is a correlation.

https://twitter.com/yconsor/status/1417117743200063489

https://twitter.com/stormchaserjs/status/1417118883463503875

Based on the data, there seems to be an inverse correlation between SST in the western Atlantic and (M)H landfalls on Southeast Florida. Am I correct?

Bump for jconsor

[jconsor]

JMA scenario of rising cell in Western Pacific continuing to dominate into mid-Aug is unlikely to verify, in my view.

 https://twitter.com/yconsor/status/1418228999285874692




 https://twitter.com/yconsor/status/1418229889300418563

[Category5Kaiju]

Perhaps as an easier reference, I'll pull up some timelines of some of the past years that people have been comparing and hypothesizing 2021 to resemble; notice how in many cases the actual intense bulk of the season does not begin until mid-August or so.

1933 (much like what CSU predicts 2021 to be, it was also a 20 NS season with one MDR hurricane in July):


1961 (also had an MDR hurricane in July):


1996 (also had an MDR hurricane in July and was almost a second year La Nina):


2001 (was an analog year CSU provided earlier this season and many people have been suggesting some track similarities):


2004 (based on the steering patterns expected by peak season for 2021 as well as a decent number of low latitude-born systems):


2008 (was an analog year CSU provided earlier this season and was also a second year La Nina):


2011 (was an analog year CSU provided earlier this season and was also a second year La Nina):


2013 (I mean, people never cease to compare a given season with this year at any point, especially early in the season; 2021 is no exception):


2017 (was an analog year CSU provided earlier this season and was also a second year La Nina with very high land impacts):


2020 (2021 comes at the heels of this very active year):

[CyclonicFury]

Perhaps as an easier reference, I'll pull up some timelines of some of the past years that people have been comparing and hypothesizing 2021 to resemble; notice how in many cases the actual intense bulk of the season does not begin until mid-August or so.

1933 (much like what CSU predicts 2021 to be, it was also a 20 NS season with one MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b421e37dac1e01b00a61fef2736d5f0.png

1961 (also had an MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b9dff2050afdd757b583a9fa1b47195.png

1996 (also had an MDR hurricane in July and was almost a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/1c95b41abbf2e2c96d0b49c159d390a7.png

2001 (was an analog year CSU provided earlier this season and many people have been suggesting some track similarities):
https://upload.wikimedia.org/wikipedia/en/timeline/90ba223b3671d4c8191b5dbcf7dd2385.png

2004 (based on the steering patterns expected by peak season for 2021 as well as a decent number of low latitude-born systems):
https://upload.wikimedia.org/wikipedia/en/timeline/d4d50aebce18875a0269ef4032684bb4.png

2008 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/e885c0aa78907642b05e266a1f80e9f0.png

2011 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/92af13febe68158251323e54eda45350.png

2013 (I mean, people never cease to compare a given season with this year at any point, especially early in the season; 2021 is no exception):
https://upload.wikimedia.org/wikipedia/en/timeline/b675c21952cf6e33f9e0e6ce7499d7be.png

2017 (was an analog year CSU provided earlier this season and was also a second year La Nina with very high land impacts):
https://upload.wikimedia.org/wikipedia/en/timeline/155d6cf6cbab384ff37c09d69ff253e9.png

2020 (also had an MDR hurricane in July, and 2021 comes at the heels of this very active year):
https://upload.wikimedia.org/wikipedia/en/timeline/035706c7b11bc4ee05424c6f4d0f2a89.png

2020 did not have a MDR hurricane in July. Isaias did not become a hurricane until it was near Hispaniola.

[InfernoFlameCat]

Perhaps as an easier reference, I'll pull up some timelines of some of the past years that people have been comparing and hypothesizing 2021 to resemble; notice how in many cases the actual intense bulk of the season does not begin until mid-August or so.

1933 (much like what CSU predicts 2021 to be, it was also a 20 NS season with one MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b421e37dac1e01b00a61fef2736d5f0.png

1961 (also had an MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b9dff2050afdd757b583a9fa1b47195.png

1996 (also had an MDR hurricane in July and was almost a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/1c95b41abbf2e2c96d0b49c159d390a7.png

2001 (was an analog year CSU provided earlier this season and many people have been suggesting some track similarities):
https://upload.wikimedia.org/wikipedia/en/timeline/90ba223b3671d4c8191b5dbcf7dd2385.png

2004 (based on the steering patterns expected by peak season for 2021 as well as a decent number of low latitude-born systems):
https://upload.wikimedia.org/wikipedia/en/timeline/d4d50aebce18875a0269ef4032684bb4.png

2008 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/e885c0aa78907642b05e266a1f80e9f0.png

2011 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/92af13febe68158251323e54eda45350.png

2013 (I mean, people never cease to compare a given season with this year at any point, especially early in the season; 2021 is no exception):
https://upload.wikimedia.org/wikipedia/en/timeline/b675c21952cf6e33f9e0e6ce7499d7be.png

2017 (was an analog year CSU provided earlier this season and was also a second year La Nina with very high land impacts):
https://upload.wikimedia.org/wikipedia/en/timeline/155d6cf6cbab384ff37c09d69ff253e9.png

2020 (also had an MDR hurricane in July, and 2021 comes at the heels of this very active year):
https://upload.wikimedia.org/wikipedia/en/timeline/035706c7b11bc4ee05424c6f4d0f2a89.png

2020 did not have a MDR hurricane in July. Isaias did not become a hurricane until it was near Hispaniola.

Hannah was a hurricane in july
Edit(wad not MDR my bad)