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

[Category5Kaiju]

https://twitter.com/BenNollWeather/status/1347932140168597505

Yeah that tweet is pretty striking to say the least. I know this is simply a model run and that many things can change going forward, but there has been a very consistent trend in these models toward a cool neutral or even weak La Nina with the Atlantic warming up very nicely. That basically will always favor at least somewhat of an active Atlantic, and to be fair I'm not really going to consider this as a likely 2013 repeat due to how extraordinary and rare the conditions that occurred during that season were. I think as of now we should consider in the back of our heads that 2021 could possibly be another above average season.

[ElectricStorm]

https://twitter.com/BenNollWeather/status/1347932140168597505

Yeah that tweet is pretty striking to say the least. I know this is simply a model run and that many things can change going forward, but there has been a very consistent trend in these models toward a cool neutral or even weak La Nina with the Atlantic warming up very nicely. That basically will always favor at least somewhat of an active Atlantic, and to be fair I'm not really going to consider this as a likely 2013 repeat due to how extraordinary and rare the conditions that occurred during that season were. I think as of now we should consider in the back of our heads that 2021 could possibly be another above average season.

Yeah I never consider any season as a potential 2013 repeat... Probably ever. But then again, I never really considered any season as a 2005 repeat. Then 2020 shoved that in my face, so I guess anything is possible at this point. Also on a side note, if 2021 does end up being above average, then all 6 name lists will have been used for an active season consecutively... That's kinda neat

[CyclonicFury]

Right now my top analogs for 2021 are 1996, 1999, 2008, and 2011. All of these years are post-moderate or stronger Niña events since the active era began in 1995. The mean of these seasons averages out to 15 named storms, 8 hurricanes, and 5 major hurricanes, with an ACE of 154.

It's extremely unlikely 2021 will come anywhere close to 2020's raw numbers. I am leaning above average right now, but lots can change since we haven't passed the SPB yet. However, I don't think a 2006-like rapid El Niño is likely, since the atmosphere is still solidly Niña like (the 30 day SOI came in at a whopping +19) and historically no first year La Niña this strong has ever been directly followed by an El Niño. I expect to see 2006 mentioned a lot this spring because it followed the previous record breaking season, but the difference in ENSO between the two years early on is very significant.

[chaser1]

https://twitter.com/BenNollWeather/status/1347932140168597505

Yeah that tweet is pretty striking to say the least. I know this is simply a model run and that many things can change going forward, but there has been a very consistent trend in these models toward a cool neutral or even weak La Nina with the Atlantic warming up very nicely. That basically will always favor at least somewhat of an active Atlantic, and to be fair I'm not really going to consider this as a likely 2013 repeat due to how extraordinary and rare the conditions that occurred during that season were. I think as of now we should consider in the back of our heads that 2021 could possibly be another above average season.

That's a reasonable perspective and pretty much how I am broadly anticipating the 2021 Atlantic Season to present. The early broad brush-stroke suggests that La Nina conditions and potentially warmer Atlantic SST's would lend to at least slightly more favorable conditions for tropical cyclone development. With that in mind the bigger questions to me will be "What will be the basin area hot-spots where genesis and storm tracks will primarily occur", "Where and how strong will the dominant mid level ridging pattern occur in the North Atlantic this upcoming season", "Will we tend to see smaller or larger tropical cyclones develop and how will this along with their points of origin ultimately imply an increased or decreased risk to the Caribbean & landfall points further west"?

There is no telling how long the upcoming season will truly play out but my own analysis is that there is a tendency for one hurricane season to tend to pick up where the prior season left off. While that is certainly an overly broad and general statement especially when taking Climo into consideration, I'm simply implying that I think that it would not be overly surprising to see two or more T.S.'s form in the GOM and West Caribbean prior to June 15. Thereafter though, I'd expect a more normal and typical progression of future tropical cyclone genesis to occur during the following couple of months. Presently, long range ENSO forecasts suggest that Pacific SST's will begin moderating from peak Nina toward normal as we approach the Fall. That leaves me with the broad assumption that an earlier and more abrupt end to Atlantic basin activity would be apt to occur compared to what 2020 displayed. My guess is that we might see 2-3 named storms form after October 1st rather then the 7 that developed in Oct/Nov of 2020. As for any current assumption that Atlantic SST's may be projected to be warmer then average, that just isn't enough of an early take away by itself to assume how this will impact the season as a whole, other then to suggest one potential favorable variable that may aid to expand a broader (geographic) range and potential earlier genesis of tropical cyclones. Depending on other atmospheric conditions in place and which area's of the basin are experiencing higher then normal SST's will only then better imply if and where an increased risk of RI might occur during the season.

LAST YEAR, NOAA predicted that 2020 would have a 60 percent chance of above normal season with 13 to 19 storms, 6 to 10 hurricanes, and 3 to 6 major hurricanes. What ultimately occurred this past season could not be reasonably predicted, blew past those numbers and was clearly record setting. I believe that NOAA and CSU will forecast a very similar forecast for the upcoming 2021 Atlantic Season, with the final outcome being within the higher end of that numeric range (atm, i'm thinking around 17/10/5). What I question the most are which future indicators will best shed light suggesting WHERE in the Atlantic basin will the greatest threat & impact potentially occur. Hopefully those tea-leaves will become slightly more telling by late Spring.

[Category5Kaiju]

Right now my top analogs for 2021 are 1996, 1999, 2008, and 2011. All of these years are post-moderate or stronger Niña events since the active era began in 1995. The mean of these seasons averages out to 15 named storms, 8 hurricanes, and 5 major hurricanes, with an ACE of 154.

It's extremely unlikely 2021 will come anywhere close to 2020's raw numbers. I am leaning above average right now, but lots can change since we haven't passed the SPB yet. However, I don't think a 2006-like rapid El Niño is likely, since the atmosphere is still solidly Niña like (the 30 day SOI came in at a whopping +19) and historically no first year La Niña this strong has ever been directly followed by an El Niño. I expect to see 2006 mentioned a lot this spring because it followed the previous record breaking season, but the difference in ENSO between the two years early on is very significant.

Yes I agree wholeheartedly, just because 2020 went Greek like 2005 does not mean the seasons and their circumstances (as well as the possible impacts on the subsequent season) are the same. In fact, the only similarities between 2020 and 2005 from my understanding are they went Greek and had above average sst anomalies in the MDR. Other than that 2020 had a strong MDR storm (looking at you Teddy..) that 2005 lacked, but 2005's ACE score was 250, which is way more than 2020's 180 (thanks to those 4 Cat 5s especially in 2005). In addition, 2005 was a bit front-loaded with the powerful July hurricanes while 2020 was very backloaded with the powerful November hurricanes and weak summer storms. So yes, with a plethora of differences to be delineated as well as the fact that 2020's La Nina is way stronger than 2005, the "oh, because 2020 went Greek like 2005 means 2021 will be inactive and dead like 2006" idea is flawed.

[toad strangler]

Right now my top analogs for 2021 are 1996, 1999, 2008, and 2011. All of these years are post-moderate or stronger Niña events since the active era began in 1995. The mean of these seasons averages out to 15 named storms, 8 hurricanes, and 5 major hurricanes, with an ACE of 154.

It's extremely unlikely 2021 will come anywhere close to 2020's raw numbers. I am leaning above average right now, but lots can change since we haven't passed the SPB yet. However, I don't think a 2006-like rapid El Niño is likely, since the atmosphere is still solidly Niña like (the 30 day SOI came in at a whopping +19) and historically no first year La Niña this strong has ever been directly followed by an El Niño. I expect to see 2006 mentioned a lot this spring because it followed the previous record breaking season, but the difference in ENSO between the two years early on is very significant.

Yes I agree wholeheartedly, just because 2020 went Greek like 2005 does not mean the seasons and their circumstances (as well as the possible impacts on the subsequent season) are the same. In fact, the only similarities between 2020 and 2005 from my understanding are they went Greek and had above average sst anomalies in the MDR. Other than that 2020 had a strong MDR storm (looking at you Teddy..) that 2005 lacked, but 2005's ACE score was 250, which is way more than 2020's 180 (thanks to those 4 Cat 5s especially in 2005). In addition, 2005 was a bit front-loaded with the powerful July hurricanes while 2020 was very backloaded with the powerful November hurricanes and weak summer storms. So yes, with a plethora of differences to be delineated as well as the fact that 2020's La Nina is way stronger than 2005, the "oh, because 2020 went Greek like 2005 means 2021 will be inactive and dead like 2006" idea is flawed.

Welp, when you have multiple storms RI close in or just before landfall ACE begins to look rather silly in determining the impacts or activity between seasons. ACE is tremendously flawed when used that way.

[CrazyC83]

Seasonal forecasting this far out is always challenging. I agree, at this time there is nothing to suggest that 2021 will be quiet and the indicators suggest above average to insanely hyperactive.

If 2021 is another year like 2020, I wonder if there will be quite a few changes to the procedures, such as naming rules?

[Category5Kaiju]

Seasonal forecasting this far out is always challenging. I agree, at this time there is nothing to suggest that 2021 will be quiet and the indicators suggest above average to insanely hyperactive.

If 2021 is another year like 2020, I wonder if there will be quite a few changes to the procedures, such as naming rules?

Yeah that is an interesting thought indeed, and with the current and expected conditions in the Atlantic I actually would not be surprised if this season defies expectations and goes over 21 NSs (maybe not 30 or somewhere near that, but who knows?). You should refer to the "Greek retirement" thread for more detailed info on some suggestions for new naming schemes, but in summary I do think that *if* in case the 2021 season does go over 21 named storms, the WMO will either implement a new 7th normal name auxiliary list or hop onto List 2 (so the 22nd storm would be Alex, and the 23rd would be Bonnie, then Colin, Danielle, and so forth for however many additional storms).

[cycloneye]

-NAO hanging on.

 https://twitter.com/webberweather/status/1348978790962253824

[cycloneye]

Wet MDR for peak of season.

 https://twitter.com/BenNollWeather/status/1349010244001693696

[Shell Mound]

Wet MDR for peak of season.

https://twitter.com/BenNollWeather/status/1349010244001693696

Steering currents look pretty similar to ‘20’s on that chart: tracks toward the Caribbean (just what Central America needs...not!), the Bay of Campeche, and the easternmost Gulf of Mexico, with a streak of above-average precipitation situated south of the Canadian Maritimes, too. Note the very dry anomalies over the Sargasso Sea and eastern subtropical Atlantic, indicating yet another strong, basin-wide Bermuda High in place. The main difference is that classical La Niña conditions appear to be much more well established than at the same time in ‘20, with upward motion solidly focused on the Maritime Continent and pronounced dry anomalies over the equatorial Pacific. What is rather scary is that the African monsoon appears to be as robust as ever, and the tongue of below-average precipitation over the Gulf of Guinea indicates a solid +AMO configuration (warm MDR, cool Gulf of Guinea). In fact, the setup almost looks even more conducive than on the early forecasts for ‘20. That hint of above-average precipitation in the BoC was also present on the early models in ‘20 and ended up precipitating an active west-central GoM. The steering currents on the NMME look ominously similar to those of ‘20, which is the last thing Gulf Coasters need!

[Category5Kaiju]

Wet MDR for peak of season.

https://twitter.com/BenNollWeather/status/1349010244001693696

Steering currents look pretty similar to ‘20’s on that chart: tracks toward the Caribbean (just what Central America needs...not!), the Bay of Campeche, and the easternmost Gulf of Mexico, with a streak of above-average precipitation situated south of the Canadian Maritimes, too. Note the very dry anomalies over the Sargasso Sea and eastern subtropical Atlantic, indicating yet another strong, basin-wide Bermuda High in place. The main difference is that classical La Niña conditions appear to be much more well established than at the same time in ‘20, with upward motion solidly focused on the Maritime Continent and pronounced dry anomalies over the equatorial Pacific. What is rather scary is that the African monsoon appears to be as robust as ever, and the tongue of below-average precipitation over the Gulf of Guinea indicates a solid +AMO configuration (warm MDR, cool Gulf of Guinea). In fact, the setup almost looks even more conducive than on the early forecasts for ‘20. That hint of above-average precipitation in the BoC was also present on the early models in ‘20 and ended up precipitating an active west-central GoM. The steering currents on the NMME look ominously similar to those of ‘20, which is the last thing Gulf Coasters need!

Yeah I do wonder though if the eastern Gulf being wetter than normal would mean the West Coast of Florida may see more impacts, at least during the JJA timeframe.

[weeniepatrol]

 https://twitter.com/BenNollWeather/status/1349739549685997577

[SFLcane]

https://twitter.com/BenNollWeather/status/1349739549685997577

Very active look to the African monsoon. Yikes!

[aspen]

For the last month, the Caribbean and MDR have been running about 0.3-0.6C above average. The Gulf has cooled significantly since it peaked at a whopping 1.0C above average in November, but it remains around average for this time of year.

[Shell Mound]

The past five seasons have been heavily Gulf-centric in terms of hurricane impacts on the CONUS. Maybe 2021 will shift toward the East Coast (Carolinas).

As for numbers, I’m going with 16/9/5, along with an ACE of ~210. I’m thinking fewer storms than in 2020, but the majors may be longer-lived this time.

Notably, the northwestern subtropical Atlantic is much warmer than it was at this time in 2020. If this persists, it could suppress the deep tropics.

 https://twitter.com/antmasiello/status/1357898431377920000

[CyclonicFury]

Several tweets about my thoughts on the 2021 Atlantic hurricane season, including the latest NMME forecast for JAS.
 https://twitter.com/CyclonicFury/status/1359244391391649796

[ClarCari]

Ughhh

At the expense of being a tinyy bit political, after the U.S. Capitol Riots and an insane end to a U.S. presidency (amongst other world leadership issues) and COVID-19 still being a big deal, 2021 is shaping to be a “make it double” to 2020’s “prepare for trouble”.

Stuff can obviously still change, but history and meteorological precedent points to an extreme unlikelihood of a suppressive Atlantic this upcoming season.
40 named storms, 30 named storms, 20..., 16.., it doesn’t even matter.. all are on the table still and more importantly depending on other factors, the Cape Verde season could roar awake more than ever this upcoming season after a less than stellar performance last season.

2004 and 2017 and maybe even worse are my biggest fears this season...

The models so far have been consistent even more so than 2005-2006 models which were unsure till an El Niño formed last second coming from a weak Cool-Neutral phase. Everyday that 05-06 warm switch becomes more and more hopeless as this current La Niña holds a firm grip and hardly any models support the chance of a warm-phase let alone anything warmer and the Atlantic SST’s show ZEROOOO chance of cooling considerably.

The only things that kept the ATL at least somewhat in check last year were the record SAL July outbreak and an uncommon string of recurving strong Typhoons influencing the TUTT.
...These are not the type of things to rely on this upcoming season, just like the hopeless 05-06 warm ENSO switch comparison.

Being wrong would be nice, but nothing of these early pre-season indicators are giving much hope of a break from the above-average activity we’ve seen in the ATL since 2016 sadly.

[Shell Mound]

CONUS Hurricane Strikes: 2016–20
Year.....Total...GoM.....EC
2016....2........1..........1
2017....3........3..........0
2018....2........1..........1
2019....2........1..........1
2020....6........5..........1
YYYY....15......11........4

CONUS Hurricane Strikes: CyclonicFury’s Analog Years (1996, 1999, 2008, 2011)
Year.....Total...GoM.....EC
1996....2........0..........2
1999....3........2..........1
2008....3........3..........0
2011....1........0..........1
YYYY....9........5..........4

If these analogs mean anything, maybe 2021 will feature more of a balance between GoM and EC hurricane landfalls than the past five seasons. We shall see. Based on historical data, the more pronounced Niña signature in the oceanic-atmospheric conditions (including +NAO via -ENSO/-PDO feedback), the stronger/farther northeast the Bermuda-Azores High, meaning hurricanes tend to make landfall farther north/east along the CONUS. Weakly Niña or cool neutral ENSO signature means less of a strongly -PDO/+NAO, hence storms making landfall farther south/west, e.g., in the GoM or on the Florida peninsula vs. the Carolinas/Mid-Atlantic. Stronger Niñas actually tend to suppress total NS due to outflow from the greater proportion of stronger hurricanes in the MDR. Bottom line: if the current trend toward a stronger global Niña signature persists through ASO, then we may see more of a hurricane threat to the East Coast north of peninsular Florida vs. the Gulf-centric activity we’ve tended to see over the past five seasons. After all, during strong(-er) Niñas storms tend to develop farther east in the MDR and become stronger, hence more opportunity to turn northward along the U.S. East Coast.

[HurricaneEnzo]

CONUS Hurricane Strikes: 2016–20
Year.....Total...GoM.....EC
2016....2........1..........1
2017....3........3..........0
2018....2........1..........1
2019....2........1..........1
2020....6........5..........1
YYYY....15......11........4

CONUS Hurricane Strikes: CyclonicFury’s Analog Years (1996, 1999, 2008, 2011)
Year.....Total...GoM.....EC
1996....2........0..........2
1999....3........2..........1
2008....3........3..........0
2011....1........0..........1
YYYY....9........5..........4

If these analogs mean anything, maybe 2021 will feature more of a balance between GoM and EC hurricane landfalls than the past five seasons. We shall see. Based on historical data, the more pronounced Niña signature in the oceanic-atmospheric conditions (including +NAO via -ENSO/-PDO feedback), the stronger/farther northeast the Bermuda-Azores High, meaning hurricanes tend to make landfall farther north/east along the CONUS. Weakly Niña or cool neutral ENSO signature means less of a strongly -PDO/+NAO, hence storms making landfall farther south/west, e.g., in the GoM or on the Florida peninsula vs. the Carolinas/Mid-Atlantic. Stronger Niñas actually tend to suppress total NS due to outflow from the greater proportion of stronger hurricanes in the MDR. Bottom line: if the current trend toward a stronger global Niña signature persists through ASO, then we may see more of a hurricane threat to the East Coast north of peninsular Florida vs. the Gulf-centric activity we’ve tended to see over the past five seasons.

CycloneFurys analogs are not painting a good picture for my neck of the woods in ENC. 3 of those 4 years featured significant impacts from storms and some of NCs most notorious Hurricanes. 96' - Bertha and Fran, 99' - Floyd and Dennis(TS), 11' - Irene

ENC has also featured a landfalling Hurricane in each of the last 3 seasons. 18' -Florence 19' -Dorian 20' -Isaias. Matthew also caused massive flooding as it passed in 16. Coincidentally this time period reminds me of the mid-to-late 90s activity we saw here.