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

[cycloneye]

Adrian, I posted the Webb twit already
6 minutes before yours so will deleite it.

Hey!

Joking no problem my friend. Should be another crazy year

Yeah

[tolakram]

Web twit? I didn't say it!

[cycloneye]

NHC is talking here.

 https://twitter.com/pppapin/status/1384874387497799683




 https://twitter.com/pppapin/status/1384880541988704261

[Category5Kaiju]

The thermodynamics with the SST anomalies as well as the predicted strong WAM sure point toward an active Atlantic; I wonder why some of these models make the Atlantic dry though. That is really perplexing imho

[jconsor]

Here are the ECMWF forecast 200 mb velocity potential anomaly charts for Jul, Aug and Sep. Note the persistent -VP anomaly centered over Africa through this period. Past several days of CFS runs have a similar VP setup for Jul-Sep. If this were to verify it would favor an early start to development in the MDR and an active season overall. These charts are from http://seasonal.meteo.fr/content/PS-previ-cartes





Note the subtle cooling from the central Pacific to near the dateline between Jun and Sep, along with warming in the tropical Atlantic and slight cooling from about 20-40N in the Atlantic subtropics. (From https://climate.copernicus.eu/charts/c3s_seasonal/). Having tropical Atl SST anomalies higher than the equatorial Pacific (and similar to slightly higher than the equatorial western Indian Ocean) is consistent with the VP forecast shown above.

[cycloneye]

Webb has this other one.

 https://twitter.com/webberweather/status/1384878398607175680

[aspen]

Webb has this other one.

https://twitter.com/webberweather/status/1384878398607175680

The more things progress, the more this is looking like a 2018-esque year: a neutral or slightly warm ENSO with a below-average Caribbean and more EPac activity than the previous year, but with an extremely strong WAM that offsets those problems and leads to an active year with some big MDR storms, as well as the potential for an early MDR start. The differences from 2018 include the fact that even a weak Niño is unlikely to be around by ASO, and the SST pattern has been much better than 2018 at this time.

If the MDR is quite favorable but the Caribbean is full of shear and dry air, perhaps we could see storms like Beryl and Issac: low-riding Cat 1s that got obliterated as they reached the Lesser Antilles.

[Category5Kaiju]

Webb has this other one.

https://twitter.com/webberweather/status/1384878398607175680

The more things progress, the more this is looking like a 2018-esque year: a neutral or slightly warm ENSO with a below-average Caribbean and more EPac activity than the previous year, but with an extremely strong WAM that offsets those problems and leads to an active year with some big MDR storms, as well as the potential for an early MDR start. The differences from 2018 include the fact that even a weak Niño is unlikely to be around by ASO, and the SST pattern has been much better than 2018 at this time.

If the MDR is quite favorable but the Caribbean is full of shear and dry air, perhaps we could see storms like Beryl and Issac: low-riding Cat 1s that got obliterated as they reached the Lesser Antilles.

Quite interestingly, it has been nearly 14 years (2007 the latest) when we actually had a long-track and powerful hurricane traverse the Caribbean. Seems like in recent years (with 2020 the exception of course) the frequency of very powerful Caribbean storms has decreased for some reason.

[toad strangler]

Webb has this other one.

https://twitter.com/webberweather/status/1384878398607175680

The more things progress, the more this is looking like a 2018-esque year: a neutral or slightly warm ENSO with a below-average Caribbean and more EPac activity than the previous year, but with an extremely strong WAM that offsets those problems and leads to an active year with some big MDR storms, as well as the potential for an early MDR start. The differences from 2018 include the fact that even a weak Niño is unlikely to be around by ASO, and the SST pattern has been much better than 2018 at this time.

If the MDR is quite favorable but the Caribbean is full of shear and dry air, perhaps we could see storms like Beryl and Issac: low-riding Cat 1s that got obliterated as they reached the Lesser Antilles.

Quite interestingly, it has been nearly 14 years (2007 the latest) when we actually had a long-track and powerful hurricane traverse the Caribbean. Seems like in recent years (with 2020 the exception of course) the frequency of very powerful Caribbean storms has decreased for some reason.

It's just the tropics being the tropics.

The CSU outlook has opened my eye the most. About 5 weeks to go before I ramp up preps.

[Shell Mound]

Webb has this other one.

https://twitter.com/webberweather/status/1384878398607175680

The more things progress, the more this is looking like a 2018-esque year: a neutral or slightly warm ENSO with a below-average Caribbean and more EPac activity than the previous year, but with an extremely strong WAM that offsets those problems and leads to an active year with some big MDR storms, as well as the potential for an early MDR start. The differences from 2018 include the fact that even a weak Niño is unlikely to be around by ASO, and the SST pattern has been much better than 2018 at this time.

If the MDR is quite favorable but the Caribbean is full of shear and dry air, perhaps we could see storms like Beryl and Issac: low-riding Cat 1s that got obliterated as they reached the Lesser Antilles.

Quite interestingly, it has been nearly 14 years (2007 the latest) when we actually had a long-track and powerful hurricane traverse the Caribbean. Seems like in recent years (with 2020 the exception of course) the frequency of very powerful Caribbean storms has decreased for some reason.

 https://twitter.com/webberweather/status/1384878942482354186



Regarding 2018: the SST configuration in the Pacific might be a bit less favourable in 2021, given east-based + anomalies in NINO 1/2 → more sinking and VWS.

[DorkyMcDorkface]

I would anticipate more warming of the Tropical Atlantic and Canary Current real soon. Models are showing a widespread relaxation of trades in these regions.


https://i.ibb.co/7K7f60G/0420.png
https://i.ibb.co/CtykrLd/8c87fa43-6d77-4624-8d74-73045b22b2b9.gif
https://i.ibb.co/s2BKXJQ/ecmwf-u850a-Mean-atl-fh120-240-1.gif

Should have probably elaborated about this more, so here ya go.

Low pressure couples with the warm SSTs associated with the Canary Current, thus reinforcing the -NAO pattern that will help to relax trades significantly for a while.




And those SSTs over there are well above average, I may add...

[cycloneye]

There are more nuggetts from Mr Noll.

 https://twitter.com/BenNollWeather/status/1385277720045801484

[DorkyMcDorkface]

Webb has this other one.

https://twitter.com/webberweather/status/1384878398607175680

The more things progress, the more this is looking like a 2018-esque year: a neutral or slightly warm ENSO with a below-average Caribbean and more EPac activity than the previous year, but with an extremely strong WAM that offsets those problems and leads to an active year with some big MDR storms, as well as the potential for an early MDR start. The differences from 2018 include the fact that even a weak Niño is unlikely to be around by ASO, and the SST pattern has been much better than 2018 at this time.

If the MDR is quite favorable but the Caribbean is full of shear and dry air, perhaps we could see storms like Beryl and Issac: low-riding Cat 1s that got obliterated as they reached the Lesser Antilles.

Quite interestingly, it has been nearly 14 years (2007 the latest) when we actually had a long-track and powerful hurricane traverse the Caribbean. Seems like in recent years (with 2020 the exception of course) the frequency of very powerful Caribbean storms has decreased for some reason.

I've noticed a strange decadal pattern when it comes to those "Caribbean Cruiser" systems. They were abundant in the 1980's and 2000's, but they seemingly disappeared in the 1990's and 2010's. I'm sure there's an explanation behind it, but I do find it mildly intriguing is all.

[AnnularCane]

Quite interestingly, it has been nearly 14 years (2007 the latest) when we actually had a long-track and powerful hurricane traverse the Caribbean. Seems like in recent years (with 2020 the exception of course) the frequency of very powerful Caribbean storms has decreased for some reason.

I've noticed a strange decadal pattern when it comes to those "Caribbean Cruiser" systems. They were abundant in the 1980's and 2000's, but they seemingly disappeared in the 1990's and 2010's. I'm sure there's an explanation behind it, but I do find it mildly intriguing is all.

With such a pattern, maybe they'll be back in the 2020's?

[SFLcane]

The more things progress, the more this is looking like a 2018-esque year: a neutral or slightly warm ENSO with a below-average Caribbean and more EPac activity than the previous year, but with an extremely strong WAM that offsets those problems and leads to an active year with some big MDR storms, as well as the potential for an early MDR start. The differences from 2018 include the fact that even a weak Niño is unlikely to be around by ASO, and the SST pattern has been much better than 2018 at this time.

If the MDR is quite favorable but the Caribbean is full of shear and dry air, perhaps we could see storms like Beryl and Issac: low-riding Cat 1s that got obliterated as they reached the Lesser Antilles.

Quite interestingly, it has been nearly 14 years (2007 the latest) when we actually had a long-track and powerful hurricane traverse the Caribbean. Seems like in recent years (with 2020 the exception of course) the frequency of very powerful Caribbean storms has decreased for some reason.

I've noticed a strange decadal pattern when it comes to those "Caribbean Cruiser" systems. They were abundant in the 1980's and 2000's, but they seemingly disappeared in the 1990's and 2010's. I'm sure there's an explanation behind it, but I do find it mildly intriguing is all.

I believe Some of it's related to decadal SST shifts I guess and linked to shifts in the Walker Circulation. Recently patterns have favored more rising motion over Africa and subsidence near the Caribbean and keep in mind global warming leads to warmer SST at higher latitudes. Increasing the range of latitudes that can support TCs but also weakening the Hadley Cell at lower latitudes (like the Caribbean). All in all a combo of oscillations and long-term shifts. We had none for a long time, then got Eta, Iota, Delta, etc last year.

[Category5Kaiju]

Quite interestingly, it has been nearly 14 years (2007 the latest) when we actually had a long-track and powerful hurricane traverse the Caribbean. Seems like in recent years (with 2020 the exception of course) the frequency of very powerful Caribbean storms has decreased for some reason.

I've noticed a strange decadal pattern when it comes to those "Caribbean Cruiser" systems. They were abundant in the 1980's and 2000's, but they seemingly disappeared in the 1990's and 2010's. I'm sure there's an explanation behind it, but I do find it mildly intriguing is all.

I believe Some of it's related to decadal SST shifts I guess and linked to shifts in the Walker Circulation. Recently patterns have favored more rising motion over Africa and subsidence near the Caribbean and keep in mind global warming leads to warmer SST at higher latitudes. Increasing the range of latitudes that can support TCs but also weakening the Hadley Cell at lower latitudes (like the Caribbean). All in all a combo of oscillations and long-term shifts. We had none for a long time, then got Eta, Iota, Delta, etc last year.

True, and after nearly 12 years of no Cat 4 or stronger storms appearing in the WCAR, it really did seem like a switch flipped last year and then we got those storms.

[NotSparta]

Just look at the similarity in location between the SSTAs and the low pressure! Seems to be some SST coupling here

[cycloneye]

Very interesting discussion here about the -NAO and warming SSTA's.

 https://twitter.com/cyclonicwx/status/1385728490494889986




 https://twitter.com/cyclonicwx/status/1385613107662307328

[Shell Mound]

Source

2021 has featured the ninth-highest ACE generation over the WPAC prior to 1 May. Of the top fifteen years on this spreadsheet, per ONI, nine ended up with El Niño: 1958, 1976, 1979, 1982, 1997, 2002, 2004, 2015, and (arguably) 2019. Three years—1956, 1962, and 1967—ended up with cool neutral ENSO. 1959 ended up with dead neutral ENSO, while 2003 ended up with warm neutral ENSO. So roughly two-thirds of the years ended up with either warm neutral or + ENSO. Therefore, I expect ENSO to play a role in counteracting the +AMO and active African monsoon by imparting convectively driven outflow and hence enhanced VWS, along with sinking air, over the Caribbean and westernmost MDR during ASO. However, the key is whether the warm anomalies in the equatorial Pacific will be concentrated in NINO 1/2 or NINO 3.4/4. If the latter, then VWS over the Caribbean and MDR would be much less. 1958, 2002, 2004, and 2019 each featured “Modoki”-type SST signatures in the equatorial Pacific during ASO. If one excludes these years as well as 2003 (whose warmest SST anomalies in the equatorial Pacific were also west-based) from the sample, then the remaining, east-based, + ENSO years—1976, 1979, 1982, 1997, and 2015—largely featured OTS MH tracks relative to the CONUS, aside from Frederic (1979). So east-based warm neutral or + ENSO is less favourable to MH landfalls and hyperactivity than west-based/“Modoki”-type warm neutral or + ENSO.

[Shell Mound]

The +PMM signature, coupled with + anomalies in NINO 1/2, would likely favour more VWS, sinking air, and a stronger TUTT over the Caribbean and western MDR. As I mentioned previously, years with the warmest anomalies concentrated in NINO 1/2 also tend to feature fewer MH landfalls on the CONUS vs. west-based or “Modoki”-type warm neutral or + ENSO setups. So even with the active African monsoon and a +AMO in place (though the warm Gulf of Guinea is more of a -AMO look), the above configuration in the Pacific is not conducive to a highly impactful season in terms of MH impacts on the CONUS or the Caribbean. The Caribbean and southwestern Atlantic would be either hostile or blocked by a trough or both. 2018 did feature Michael and Florence, but it was a “Modoki”-type (west-based + ENSO) year, not an east-based warm neutral or + ENSO. A dangerous setup would be reversed, with the + anomalies in NINO 3.4/4 and the cool in NINO 1/2. (Incidentally, I don’t think a single Atlantic season with both ACE ≥ 150 and east-based warm neutral/+ ENSO has been registered since 1950. Yet CSU’s April forecast has consistently underestimated seasonal ACE since 2016, and this April’s forecast calls for hyperactivity and an ACE of 150.)