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

[Category5Kaiju]

I'm going to put this into pretty plain words: the fact is we had the first major hurricane form on August 20, which is earlier than what happened nearly 13 years of the 18 years since at least 2004 regarding this same event. Interpret that info however you want, but imho this is really an indication that the Atlantic is primed for intense activity in the not-so-distant future.

[ElectricStorm]

I'm going to put this into pretty plain words: the fact is we had the first major hurricane form on August 20, which is earlier than what happened nearly 13 years of the 18 years since at least 2004 regarding this same event. Interpret that info however you want, but imho this is really an indication that the Atlantic is primed for intense activity in the not-so-distant future.

I don't think a major that early is an indicator by itself. 2009 had Bill before 8/20 but it was a slow season. 2015 had Danny in August and it was a slow season as well. 2007 had Dean early but other than that and Felix it was a slow season. So I don't think an early major is an indicator by itself. However... The fact that we had one of the earliest MDR hurricanes on record, combined with the early major, and the fact that the season is already 8/3/1 with no signs of slowing down is a better indicator that the season will be active. IMO

[Steve]

Is the MJO typically less of a factor during the peak months?

Grain of salt as I've only been watching it a few seasons - but not that I've noticed. It does what it does. It will occasionally return to the center/neutral phase based on convective activity in the Indian and Pacific Oceans. Sometimes it's not the dominant signal. Maybe you have a La Nina or El Nino coming on strong. Sometimes you'll have a really strong +/-NAO, +/- EPO or whatever being the dominant driver of activity. There could be extreme SST anomalies or blocking patterns that influence more.

It really just depends on what's going on out there in the atmosphere from around the date line east to the Indian Subcontinent and then what's on the table in the Atlantic. The convective influence propagates west to east. Sometimes the MJO doesn't even make it into the Atlantic Basin as the impulse is too weak to get this far "east."

[weeniepatrol]

I don't think a major that early is an indicator by itself. 2009 had Bill before 8/20 but it was a slow season. 2015 had Danny in August and it was a slow season as well.

Strong el nino years. Poor examples

[Shell Mound]

Well, Henri certainly continued the trend of storms mostly underperforming thus far, Grace notwithstanding.

Are you trolling? What value does this post add to this thread?

I was referring to the fact that several models at one point or another showed most of the storms becoming stronger than they actually did, save Grace. For example, there were models that showed Elsa, Fred, and Henri becoming stronger than they actually did. As far as Henri is concerned, several areas that expected to receive heavy rainfall, especially in portions of Connecticut and Massachusetts, have thus far received far less rain than actually verified, fortunately, though locally Henri came closer to matching forecast totals, primarily in portions of New Jersey and New York State.

Models underestimated the shear over Henri. Why trust them? They have consistently shown more favourable conditions than have actually ended up verifying, at least insofar as shear and dry air are concerned, especially in the MDR.

I agree, so why trust them when they show no activity?

My perception was that the models were showing conditions becoming more conducive too soon, so I trust their “corrections” that show less favourable conditions.

[tolakram]

I was referring to the fact that several models at one point or another showed most of the storms becoming stronger than they actually did

That's what I call cherry picking. You have to choose the runs that under performed. I can cherry pick as well, but instead I neither declare the season hyper active or slower than expected, I just observe because neither one of us will be able to correctly predict the rest of the season.

12Z GFS and Euro from last Monday. Which storms under performed?





If I had an older model run handy I could declare Elsa as over performing near the Islands.

[Teban54]

One advantage that 2021's CV season has over 2020 is the lack of recurving WPAC typhoons. Between late August and early September 2020, the WPAC produced three back-to-back recurving typhoons (Bavi, Maysak and Haishen). They induced a strong TUTT in the Atlantic just in time for the peak season, and sheared most of the CV storms present during that time such as Paulette, Rene and Vicky. It was part of the reason why 2020's CV season was a lot more anemic than expected pre-season (save Teddy).

The 2021 WPAC season looks even less active during this time frame than last year, so a typhoon-induced TUTT is likely out of consideration (though TUTTs may still exist for other reasons).

[aspen]

Welp, that escalated quickly.

[ElectricStorm]

I don't think a major that early is an indicator by itself. 2009 had Bill before 8/20 but it was a slow season. 2015 had Danny in August and it was a slow season as well.

Strong el nino years. Poor examples

That's why I'm saying an early major by itself isn't a good indicator. But the early major combined with everything else so far is

[Category5Kaiju]

Welp, that escalated quickly.
https://i.imgur.com/h4oQJgc.png

If all three theoretically become named storms before August’s end, we would only be two storms behind last year’s pace and one storm behind 2005’s pace. Either way, I seriously think we are in for another high NS count, above average and very active year. We’ll see, but as I have mentioned in an earlier post a month or so ago, reaching Adria and the aux list may not be a very far-fetched notion.

[aspen]

This frenzy of storms in late August through early September reminds me a bit of 1995, if all of the predicted systems and AOIs develop. 1995 saw Humberto and Iris form in the MDR and recurve (potentially similar to 97L and 98L, except 97L won’t develop until the subtropics), and were then followed by the classic MDR long-tracker Luis. Interesting how Humberto and Iris didn’t leave a break in the ridge that lasted long enough for Luis to find an exit, which is something that could happen with 97L, 98L, and the system the Euro/EPS/CMC develops on August 31st/September 1st.

If 97L, 98L, soon-to-be-99L (the Gulf system), and the turn-of-the-month MDR system all develop within the next 240hr, we’ll be at Larry by the first few days of September, two weeks ahead of 2017 and just behind 1995. Some of these systems could have the potential to become hurricanes. 12 systems by September 1st would could us on track for another 20 or more NS year. I don’t see any season cancel or bearish predictions continuing for much longer with the massive potential over just the next ten days.

[JetFuel_SE]

One advantage that 2021's CV season has over 2020 is the lack of recurving WPAC typhoons. Between late August and early September 2020, the WPAC produced three back-to-back recurving typhoons (Bavi, Maysak and Haishen). They induced a strong TUTT in the Atlantic just in time for the peak season, and sheared most of the CV storms present during that time such as Paulette, Rene and Vicky. It was part of the reason why 2020's CV season was a lot more anemic than expected pre-season (save Teddy).

The 2021 WPAC season looks even less active during this time frame than last year, so a typhoon-induced TUTT is likely out of consideration (though TUTTs may still exist for other reasons).

Vicky was mostly sheared by Teddy's outflow iirc.

[Zonacane]

 https://twitter.com/stormchasernick/status/1429889885670871045

[AlphaToOmega]

https://twitter.com/stormchasernick/status/1429889885670871045

I am very ready for a Minnesota hurricane.

[Hammy]

One advantage that 2021's CV season has over 2020 is the lack of recurving WPAC typhoons. Between late August and early September 2020, the WPAC produced three back-to-back recurving typhoons (Bavi, Maysak and Haishen). They induced a strong TUTT in the Atlantic just in time for the peak season, and sheared most of the CV storms present during that time such as Paulette, Rene and Vicky. It was part of the reason why 2020's CV season was a lot more anemic than expected pre-season (save Teddy).

The 2021 WPAC season looks even less active during this time frame than last year, so a typhoon-induced TUTT is likely out of consideration (though TUTTs may still exist for other reasons).

2020 also had an overactive WAM, leading to gyre waves or systems simply ending up too far north:
Isaias was a sprawling mess in the MDR
Laura took quite a long time to consolidate due to competing waves
Nana's wave was trackable for awhile but again took days to actually separate from the monsoon trough
Paulette was actually flung north over cooler water (and closer to an Azores ULL) by the gyre to it's west
Rene came off at around 15N, surrounded by dust, and then proceeded to move NW over cooler waters
Vicky similarly came off close to 15N and moved NW, pushing it into Teddy's outflow channel
Even Teddy (one of only three storms to become a hurricane east of 60W, and the only one in the tropical Atlantic) took days to finally consolidate due to how sprawling the wave was.

I am curious as to why the tropical Atlantic still seems less than favorable at the moment, as the models (at least in the short term) point to another heavily west and north-based burst of activity.

[aspen]

One advantage that 2021's CV season has over 2020 is the lack of recurving WPAC typhoons. Between late August and early September 2020, the WPAC produced three back-to-back recurving typhoons (Bavi, Maysak and Haishen). They induced a strong TUTT in the Atlantic just in time for the peak season, and sheared most of the CV storms present during that time such as Paulette, Rene and Vicky. It was part of the reason why 2020's CV season was a lot more anemic than expected pre-season (save Teddy).

The 2021 WPAC season looks even less active during this time frame than last year, so a typhoon-induced TUTT is likely out of consideration (though TUTTs may still exist for other reasons).

2020 also had an overactive WAM, leading to gyre waves or systems simply ending up too far north:
Isaias was a sprawling mess in the MDR
Laura took quite a long time to consolidate due to competing waves
Nana's wave was trackable for awhile but again took days to actually separate from the monsoon trough
Paulette was actually flung north over cooler water (and closer to an Azores ULL) by the gyre to it's west
Rene came off at around 15N, surrounded by dust, and then proceeded to move NW over cooler waters
Vicky similarly came off close to 15N and moved NW, pushing it into Teddy's outflow channel
Even Teddy (one of only three storms to become a hurricane east of 60W, and the only one in the tropical Atlantic) took days to finally consolidate due to how sprawling the wave was.

I am curious as to why the tropical Atlantic still seems less than favorable at the moment, as the models (at least in the short term) point to another heavily west and north-based burst of activity.

The tropical Atlantic likely won’t be unfavorable for much longer. Some of the models have shown the TUTT backing down, and/or a potential MDR long-tracker forming in 8-10 days. SAL should also die down after this last outbreak.

The waves this year have had much better luck than last year. The precursors for Elsa, Fred, and Grace were all at normal to low latitudes, and were more compact than the massive sloppy gyre waves of 2020. 98L is also quite a healthy looking wave, although there’s no guarantee it develops.

[tolakram]

I am curious as to why the tropical Atlantic still seems less than favorable at the moment, as the models (at least in the short term) point to another heavily west and north-based burst of activity.

My guess is some long term pattern we don't yet understand. I haven't reviewed all the past years, I'm wondering if we had a similar stretch of western based seasons.

[Iceresistance]

I am curious as to why the tropical Atlantic still seems less than favorable at the moment, as the models (at least in the short term) point to another heavily west and north-based burst of activity.

My guess is some long term pattern we don't yet understand. I haven't reviewed all the past years, I'm wondering if we had a similar stretch of western based seasons.

Most of the powerful storms in 2005 & 2020 were western-based . . .

2005


2020

[tolakram]

I am curious as to why the tropical Atlantic still seems less than favorable at the moment, as the models (at least in the short term) point to another heavily west and north-based burst of activity.

My guess is some long term pattern we don't yet understand. I haven't reviewed all the past years, I'm wondering if we had a similar stretch of western based seasons.

Most of the powerful storms in 2005 & 2020 were western-based . . .

2005
https://s9.gifyu.com/images/1745px-2005_Atlantic_hurricane_season_summary_map.png

2020
https://s9.gifyu.com/images/1745px-2020_Atlantic_hurricane_season_summary_map.png

Right, but why? There's a narrative of late that we aren't getting long tracking CV storms like we used to. Is this really true?

[AlphaToOmega]

My guess is some long term pattern we don't yet understand. I haven't reviewed all the past years, I'm wondering if we had a similar stretch of western based seasons.

Most of the powerful storms in 2005 & 2020 were western-based . . .

2005
https://s9.gifyu.com/images/1745px-2005_Atlantic_hurricane_season_summary_map.png

2020
https://s9.gifyu.com/images/1745px-2020_Atlantic_hurricane_season_summary_map.png

Right, but why? There's a narrative of later that we aren't getting long tracking CV storms like we used to. Is this really true?

2017 would say otherwise