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

[aspen]

2021 is one of a handful of years with a deep tropics MDR system, so once again looking to see the average of similar years, I limited this sample to seasons after 1980 with at least one July system born from an AEW east of 70W and south of 25N, regardless of intensity. The seasons that fit this criteria are 1989, 1990, 1995 (just barely), 1996, 1998, 2003, 2005, 2008, 2013, 2017, 2018, and 2020. Their average numbers are:
—17.3 named storms
—9.1 hurricanes
—3.9 majors
—162.80 ACE

I then decided to remove 2013 from the calculations, because despite having two July MDR systems, the season’s H, MH, and ACE total were destroyed by the abnormal collapse of the THC, thereby making it an outlier due to the occurrence of a rare event. The new average is:
—17.5 named storms
—9.7 hurricanes
—4.3 majors
—174.32 ACE

Since 2021 now falls into this category with Hurricane Elsa, it is quite probable that the year ends up with 15-19 named storms, 7-10 hurricanes, 3-5 majors, and an ACE total of at least 140-150.

[Category5Kaiju]

On the other hand, does Elsa’s compact size while intensifying over the Windwards suggest that it is less representative of background conditions than a larger TC?

In other words, does the fact that Elsa was a relatively small system suggest that it says less about overall conditions in 2021 than a larger system might have...?

July storms aren't typically that large in the first place as pressures in that part of the Atlantic in early July are generally higher than in August and September. Even Emily in 2005 (the most active July on record, and the strongest July hurricane on record) was small through most of it's life prior to crossing the Yucatan and spreading out. Both Berthas in 1996 and 2008 were also fairly small once they organized.

The fact that Elsa is weakening in the Caribbean, unlike storms in June/July 1933 and 2005, suggests this season is likely to be less favourable than those two.

I don’t mean any offense, but I strongly disagree with this notion. The fact that we had Elsa by itself is a warning sign for what is to come, and here’s a list of very bad hurricane seasons that did not have a July MDR hurricane: 2004, 2017, 1969, 2020. I think this season has shown to overachieve based on this metric alone, and if anything the fact that Elsa survived an otherwise hostile ECAR and took a cruiser-like path may suggest that we could even see the return of Caribbean cruisers later this season assuming this is an indication that conditions in this region of the Atlantic are abnormally favorable.

[AlphaToOmega]

2021 is one of a handful of years with a deep tropics MDR system, so once again looking to see the average of similar years, I limited this sample to seasons after 1980 with at least one July system born from an AEW east of 70W and south of 25N, regardless of intensity. The seasons that fit this criteria are 1989, 1990, 1995 (just barely), 1996, 1998, 2003, 2005, 2008, 2013, 2017, 2018, and 2020. Their average numbers are:
—17.3 named storms
—9.1 hurricanes
—3.9 majors
—162.80 ACE

I then decided to remove 2013 from the calculations, because despite having two July MDR systems, the season’s H, MH, and ACE total were destroyed by the abnormal collapse of the THC, thereby making it an outlier due to the occurrence of a rare event. The new average is:
—17.5 named storms
—9.7 hurricanes
—4.3 majors
—174.32 ACE

Since 2021 now falls into this category with Hurricane Elsa, it is quite probable that the year ends up with 15-19 named storms, 7-10 hurricanes, 3-5 majors, and an ACE total of at least 140-150.

I would exclude 1989 and 1990 for being -AMO. With that, the seasons with early July MDR activity are 1995, 1996, 1998, 2003, 2005, 2008, 2017, 2018, and 2020. In that case, the averages are:
—18.66 storms
—10.22 hurricanes
—4.88 major hurricanes
—186.77 ACE

Based on these analogs alone, a reasonable forecast for 2021 would be 18-19 storms, 10-11 hurricanes, 4-5 major hurricanes, and 180-190 ACE.

[Deshaunrob17]

1998 season was an interesting year IMO. The year before we had the super elnino . During 1998 , La Niña signal started to build from the west in the Pacific . However, when September came, this Eastern Pacific still had residual El Niño signal as it was still pretty anomalously warm. Even though the eastern side of the Pacific was warm, we had Hurricane Gorges and Hurricane Mitch in the Caribbean. However, the Caribbean wasn’t too active compared to the MDR (I’m guessing the the residual warm pool in the Epac).

I’m looking at this. Year and it seems like the Eastern side of the Pacific taking quite some time to cool down . The Central Pacific seems neutral.. Not too sure about it being a heavy Caribbean year, but definitely looks like it will be a heavy MDR year

[aspen]

According to CSU, we’re up to 8.0 units of ACE so far. Maybe it’ll be up to 10 units by the time Elsa dissipates, very impressive for the first week of July. In fact, this is roughly the average ACE by early August.

http://tropical.atmos.colostate.edu/Realtime/

[cycloneye]

Fear August.

 https://twitter.com/webberweather/status/1411727983174328322

[aspen]

Fear August.

https://twitter.com/webberweather/status/1411727983174328322

The enhanced CCKW following the suppressive wave will probably lead to a spike in TC activity starting in the last third of July. That’s when I think we’ll get our next hurricane and maybe even the first major.

[AlphaToOmega]

A suppressed MJO phase does not exclude subtropical development.

[Hammy]

On the other hand, does Elsa’s compact size while intensifying over the Windwards suggest that it is less representative of background conditions than a larger TC?

In other words, does the fact that Elsa was a relatively small system suggest that it says less about overall conditions in 2021 than a larger system might have...?

July storms aren't typically that large in the first place as pressures in that part of the Atlantic in early July are generally higher than in August and September. Even Emily in 2005 (the most active July on record, and the strongest July hurricane on record) was small through most of it's life prior to crossing the Yucatan and spreading out. Both Berthas in 1996 and 2008 were also fairly small once they organized.

The fact that Elsa is weakening in the Caribbean, unlike storms in June/July 1933 and 2005, suggests this season is likely to be less favourable than those two.

By that same logic, you could have said that because Isaias was weakening in the Bahamas suggests 2020 wouldn't be as favorable as 2019.

Fear August.

https://twitter.com/webberweather/status/1411727983174328322

The enhanced CCKW following the suppressive wave will probably lead to a spike in TC activity starting in the last third of July. That’s when I think we’ll get our next hurricane and maybe even the first major.

What I'm taking from this is that July is essentially trying to behave like August, given how often the middle of August itself has had complete lulls only to heat up at the end.

[AlphaToOmega]

The one advantage the Atlantic has over the East Pacific is subtropical development. I do not think subtropical storms form in the East Pacific (if they do, they must be EXTREMELY rare), but they are quite common in the Atlantic. This year, both the subtropics and the tropics are forecasted to have above-average sea surface temperatures, which would enhance both tropical and subtropical activity.

[Kingarabian]

The one advantage the Atlantic has over the East Pacific is subtropical development. I do not think subtropical storms form in the East Pacific (if they do, they must be EXTREMELY rare), but they are quite common in the Atlantic. This year, both the subtropics and the tropics are forecasted to have above-average sea surface temperatures, which would enhance both tropical and subtropical activity.

They do form but they're not classified.

[Category5Kaiju]

Also interesting thing to note: once Elsa hits Florida, we would be ahead of 2020 in the number of NS landfalls in the continental US based on when we are in the calendar.

[aspen]

It is only July 5th, and there is a Caribbean Cruiser that was a MDR hurricane and had the chance to become a major. If the Atlantic was able to pump this out in a historically “eh” month, what will it be putting out once ASO arrives? The position of the ITCZ, as posted by Hammy, seems to be better for MDR activity, so therefore it could favor more low-riders that turn into Caribbean Cruisers.

[CyclonicFury]

After Elsa, the Atlantic will likely have a lull. The exact duration of how long is hard to predict, but it would not be surprising to not see a TC form for 2-3 weeks. That being said, there's always potential for unexpected short lived weak storms. With the upcoming suppressed CCKW, we could see a significant SAL outbreak as well. Then it'll be season cancel season.

I'd expect the Atlantic to really get going in late August, as usual. Maybe a few named storms and even a hurricane before then.

[AlphaToOmega]

As of now, most tropical cyclogenesis has been in the subtropics (Ana, Bill, and Danny). One of these was in May; the two others were in June. We would see 1-2 tropical cyclones form in the subtropics in July. The latest CFSv2 run shows a suppressed phase until ~July 19. At that point, activity should ramp up again.

[Category5Kaiju]

After Elsa, the Atlantic will likely have a lull. The exact duration of how long is hard to predict, but it would not be surprising to not see a TC form for 2-3 weeks. That being said, there's always potential for unexpected short lived weak storms. With the upcoming suppressed CCKW, we could see a significant SAL outbreak as well. Then it'll be season cancel season.

I'd expect the Atlantic to really get going in late August, as usual. Maybe a few named storms and even a hurricane before then.

While I agree with you, I think the GFS has been hinting at some development in the WCAR as early as next week. We'll see if that verifies, but this just shows you that even during a suppressed phase how activity can still occur.

[AlphaToOmega]

It is also possible for major hurricanes to form in the subtropics. This is what happened with Hurricane Epsilon (2020).

[Category5Kaiju]

Or Hurricane Alex back in 2004, that became a Cat 3 at an unusually high latitude

[captainbarbossa19]

This is probably one of the most favorable SST patterns for an active season
https://www.tropicaltidbits.com/analysis/models/cfs-mon/2021070400/cfs-mon_01_ssta_global_2.png

Somehow, I think the western part of the basin may be more favorable compared to the MDR yet again this season. Wind shear sure has been relatively low in the Caribbean lately.

[AlphaToOmega]

This is probably one of the most favorable SST patterns for an active season
https://www.tropicaltidbits.com/analysis/models/cfs-mon/2021070400/cfs-mon_01_ssta_global_2.png

Somehow, I think the western part of the basin may be more favorable compared to the MDR yet again this season. Wind shear sure has been relatively low in the Caribbean lately.

Last year's SST pattern was horrible for MDR development. The MDR was practically below-average. I am not seeing that on the forecast.