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

[NotSparta]

If the NAO is strongly positive during the same timeframe, then the coolish MDR + any EPAC convection + TUTT + ITCZ-related VWS could really kill the CV season.

EPAC convection looks suppressed, and you can't have the TUTT and an active ITCZ shearing the tropics at the same time. If the ITCZ is that strong, all the upper level heat release and -VP generation will severely stunt the TUTT

Do you think the active ITCZ could partly offset the coolish MDR (implied stability) and thus still produce some large storms, à la Frances, Ivan, or Irma?

https://twitter.com/DerekOrtt/status/1415076770743832581

Well the cool anomalies aren't really where the ITCZ so as long it doesn't move into the cooler waters there's no real stability at that latitude. Wouldn't be surprised to see some genesis modes similar to Elsa where a low latitude wave gets helped by low level westerly surges

[Teban54]

Question from a newbie: So it seems like several 2021 VP forecasts, as well as analyses of past active seasons, show sinking air in the western MDR, Caribbean and Gulf. Why is that not a negative factor?

[aspen]

If the NAO is strongly positive during the same timeframe, then the coolish MDR + any EPAC convection + TUTT + ITCZ-related VWS could really kill the CV season.

EPAC convection looks suppressed, and you can't have the TUTT and an active ITCZ shearing the tropics at the same time. If the ITCZ is that strong, all the upper level heat release and -VP generation will severely stunt the TUTT

Do you think the active ITCZ could partly offset the coolish MDR (implied stability) and thus still produce some large storms, à la Frances, Ivan, or Irma?

https://twitter.com/DerekOrtt/status/1415076770743832581

I’m thinking that due to the active and south-displaced ITCZ, we could see tracks similar to Dennis, Ivan, Felix, Maria, and Dorian — low-latitude genesis in the western half of the MDR or very close to the Lesser Antilles, where the systems either continue west (Ivan, Felix) or turn north earlier (Dennis, Maria, Dorian). This would indeed offset the possible negative impacts of an SST configuration like this: any developing waves would remains out of the way of cooler SSTs and stable air. An alternative possibility is that we get MDR storms like Paulette and Teddy, where they don’t reach their peak until they get north of 20N and into the subtropics. However, the strong ridging forecasts that SFLcane has been posting could prevent this.

Or this season becomes yet another year of west-based development and a lackluster MDR compared to the Caribbean and Gulf.

[AlphaToOmega]

EPAC convection looks suppressed, and you can't have the TUTT and an active ITCZ shearing the tropics at the same time. If the ITCZ is that strong, all the upper level heat release and -VP generation will severely stunt the TUTT

Do you think the active ITCZ could partly offset the coolish MDR (implied stability) and thus still produce some large storms, à la Frances, Ivan, or Irma?

https://twitter.com/DerekOrtt/status/1415076770743832581

I’m thinking that due to the active and south-displaced ITCZ, we could see tracks similar to Dennis, Ivan, Felix, Maria, and Dorian — low-latitude genesis in the western half of the MDR or very close to the Lesser Antilles, where the systems either continue west (Ivan, Felix) or turn north earlier (Dennis, Maria, Dorian). This would indeed offset the possible negative impacts of an SST configuration like this: any developing waves would remains out of the way of cooler SSTs and stable air. An alternative possibility is that we get MDR storms like Paulette and Teddy, where they don’t reach their peak until they get north of 20N and into the subtropics. However, the strong ridging forecasts that SFLcane has been posting could prevent this.

Or this season becomes yet another year of west-based development and a lackluster MDR compared to the Caribbean and Gulf.

Just like 2005 and 2020

It is quite interesting that the most active hurricanes seasons (2005 and 2020) were not heavy MDR seasons.

[SFLcane]

Do you think the active ITCZ could partly offset the coolish MDR (implied stability) and thus still produce some large storms, à la Frances, Ivan, or Irma?

https://twitter.com/DerekOrtt/status/1415076770743832581

I’m thinking that due to the active and south-displaced ITCZ, we could see tracks similar to Dennis, Ivan, Felix, Maria, and Dorian — low-latitude genesis in the western half of the MDR or very close to the Lesser Antilles, where the systems either continue west (Ivan, Felix) or turn north earlier (Dennis, Maria, Dorian). This would indeed offset the possible negative impacts of an SST configuration like this: any developing waves would remains out of the way of cooler SSTs and stable air. An alternative possibility is that we get MDR storms like Paulette and Teddy, where they don’t reach their peak until they get north of 20N and into the subtropics. However, the strong ridging forecasts that SFLcane has been posting could prevent this.

Or this season becomes yet another year of west-based development and a lackluster MDR compared to the Caribbean and Gulf.

Just like 2005 and 2020

It is quite interesting that the most active hurricanes seasons (2005 and 2020) were not heavy MDR seasons.

No, but they did have much warmer SSTs in the Caribbean and Western Atlantic than we have now.

[Category5Kaiju]

Interesting sst setup to say the least. I do wonder though if that EGULF cool wake is from Elsa.

[captainbarbossa19]

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

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

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

Interesting sst setup to say the least. I do wonder though if that EGULF cool wake is from Elsa.

Looks like the MDR may be beginning to heat up. It is certainly not too late for the MDR to recover in time for peak season activity. The Gulf can quickly rebound too in a few weeks. An example of this was last year with Hurricane Hanna cooling the western Gulf. By the time Hurricane Laura arrived, the Gulf had completely recovered from the previous cooling.

[Teban54]

EPAC convection looks suppressed, and you can't have the TUTT and an active ITCZ shearing the tropics at the same time. If the ITCZ is that strong, all the upper level heat release and -VP generation will severely stunt the TUTT

Do you think the active ITCZ could partly offset the coolish MDR (implied stability) and thus still produce some large storms, à la Frances, Ivan, or Irma?

https://twitter.com/DerekOrtt/status/1415076770743832581

I’m thinking that due to the active and south-displaced ITCZ, we could see tracks similar to Dennis, Ivan, Felix, Maria, and Dorian — low-latitude genesis in the western half of the MDR or very close to the Lesser Antilles, where the systems either continue west (Ivan, Felix) or turn north earlier (Dennis, Maria, Dorian). This would indeed offset the possible negative impacts of an SST configuration like this: any developing waves would remains out of the way of cooler SSTs and stable air. An alternative possibility is that we get MDR storms like Paulette and Teddy, where they don’t reach their peak until they get north of 20N and into the subtropics. However, the strong ridging forecasts that SFLcane has been posting could prevent this.

Or this season becomes yet another year of west-based development and a lackluster MDR compared to the Caribbean and Gulf.

Teddy actually reached Cat 4 just south of 20N, and peaked at 120 kts at 20.4N. Close enough to be considered in MDR imo.

Edit: Also, even such a scenario can also be potentially damaging. Florence '18 is a great example: it was pretty far north by the time it weakened to a TS, before it continued west, entered the (anomalously) warm subtropical region, and became a Cat 4 threatening the US mainland.

[GrayLancer18]

Looks like things might be quiet into August but will get wild from Sep into October.

 https://twitter.com/webberweather/status/1415342177136386051

[Category5Kaiju]

After the past recent years, it almost seems as if hurricane season has been shifted later into the calendar year; what I mean by this is it has been a while since we last saw a season with a lot of August and September activity with little October activity rather than the more recent patterns of little August activity but a lot of September and October activity. In fact, the past active stretch of seasons since 2016 did not feature their first major hurricane until late August or so. I wonder if 2021 will follow this trend or if it will surprise us with a major hurricane earlier than late August or so.

[Shell Mound]

I suspect that the very +NAO and enhanced WAR during ASO implies that the U.S. may be less at risk in 2021 than, say, Central America. 2007 comes to mind.

With more homegrown and subtropical development vs. formation in the MDR, I suspect that ACE will likely underperform relative to expectations once again.

[Category5Kaiju]

I suspect that the very +NAO and enhanced WAR during ASO implies that the U.S. may be less at risk in 2021 than, say, Central America. 2007 comes to mind.

While I am definitely not implying in any way that I'd rather have the storms hit other countries in any way, I really hope Central America does not experience another 2007 per se; they've had enough with Eta and Iota from last year.

[psyclone]

This thread has added 14 pages in a week. One thing i've noticed over the years...when there's lots happening here, there's nothing happening out there. Here's to hoping for another month of this at a minimum.

[Category5Kaiju]

This thread has added 14 pages in a week. One thing i've noticed over the years...when there's lots happening here, there's nothing happening out there. Here's to hoping for another month of this at a minimum.

When there's an active storm (especially one that is threatening land or becoming a very powerful threat), I could only imagine how quiet the indicators thread would be but the thread dedicated to that storm extremely busy.

[psyclone]

This thread has added 14 pages in a week. One thing i've noticed over the years...when there's lots happening here, there's nothing happening out there. Here's to hoping for another month of this at a minimum.

When there's an active storm (especially one that is threatening land or becoming a very powerful threat), I could only imagine how quiet the indicators thread would be but the thread dedicated to that storm extremely busy.

This is true and i thoroughly enjoy both the discussion and the downtime. We're probably going to have a season that's at least somewhat above normal so enjoy the intermission.

[BYG Jacob]

The southern, and much warmer, band of the MDR is colocated with the ITCZ currently.

[Stormybajan]

The way I see it, theres more positive signals in the atlantic than negative. Im not sure stability realistically will be a problem, hasnt the last 5 years generally had "below average instability" from that chart I see every once in a while? Look where we are with 5 above average seasons in a row. The ITCZ right now I am not sure if it is indeed more south than usual for mid July, or not, but it does look quite convectively active to me..in a negative MJO background state.However, the big factor as I've stated before is the return of cool neutral or weak La Nina conditions which means less shear overall in the Atlantic basin. Finally, based on the SST set up right now favoring the lower MDR region I must say that I am still extremely wary of a strong Hurricane moving through the islands and then into the caribbean big or small in size

[MarioProtVI]

I suspect that the very +NAO and enhanced WAR during ASO implies that the U.S. may be less at risk in 2021 than, say, Central America. 2007 comes to mind.

With more homegrown and subtropical development vs. formation in the MDR, I suspect that ACE will likely underperform relative to expectations once again.

Let’s see how this post stacks up in real time later on (likely will be wrong) You said Florida wouldnt be at risk last year and we know how that turned out. Things can change quickly, and I think the MDR and ACE will outdo predictions by a bit.

[Category5Kaiju]

I suspect that the very +NAO and enhanced WAR during ASO implies that the U.S. may be less at risk in 2021 than, say, Central America. 2007 comes to mind.

With more homegrown and subtropical development vs. formation in the MDR, I suspect that ACE will likely underperform relative to expectations once again.

Let’s see how this post stacks up in real time later on (likely will be wrong) You said Florida wouldnt be at risk last year and we know how that turned out. Things can change quickly, and I think the MDR and ACE will outdo predictions by a bit.

Florida did not get hit with any major hurricanes last year though, but it did still experience some TS hits, like from Eta. I do think this year may be different though. If Gulf ridging is not strong this year, then the predicted strong ridging over Eastern Canada could send storms westward but allow them to curve northward (kind of like what we saw with Elsa), and this would almost certainly put Florida at risk later this season if the ridging pattern comes to fruition.

[Yellow Evan]

 https://twitter.com/yconsor/status/1415261077580009473