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

[Stormybajan]

That SOI is looking EXTREMELY POSITIVE.
https://www.longpaddock.qld.gov.au/soi/

For the members who dont know when you say Extremely Positive, what it means?

It means the 30-day average is extremely positive. The pressure in Tahiti is much higher than the pressure in Darwin, so winds blow from Tahiti to Darwin from east to west. This is indicating strong easterly winds in the Pacific.

Soo essentially.. the atmosphere is coupling and heading towards La Nina? Not good.

[Category5Kaiju]

At this point I think the question would be "how strong can this La Nina get?" I really hope it's not weak as historically weak La Ninas have been associated with the more active and damaging hurricane seasons compared to strong or moderate La Ninas.

[toad strangler]

At this point I think the question would be "how strong can this La Nina get?" I really hope it's not weak as historically weak La Ninas have been associated with the more active and damaging hurricane seasons compared to strong or moderate La Ninas.

Just cool neutral ENSO has been enough in the past.

[SFLcane]

 https://twitter.com/sammyhadiwx/status/1415703069229260800

[cycloneye]

At this point I think the question would be "how strong can this La Nina get?" I really hope it's not weak as historically weak La Ninas have been associated with the more active and damaging hurricane seasons compared to strong or moderate La Ninas.

Just cool neutral ENSO has been enough in the past.

Cool neutral brought the latest big landfall, Maria. In my case I prefer la Niña as PR landfalls have been way less.

[USTropics]

For those more interested in the Atlantic equatorial mode (or Atlantic Nino), I've broken down the four main varieties (early-termination, persistent, early-onset, late-onset; there are 4 mixed-signals as well but for brevity sake will not include those) with descriptions/observations and various anomaly composites. The anomaly images include SSTAs, precipitation rates, 500mb heights, mid-level relative humidity, zonal 10m winds, meridional 10m winds, and omega 200mb velocity potential. This is broken into seasonal outlooks: (1) December, January, February (DJF); (2) March, April, May (MAM); (3) June, July, August (JJA); and (4) September, October, November (SON). First, here is a description/observations of each of the four major types of Atlantic Nino:

Early termination
Years: 1974, 1991, and 1996
SSTA observations: Rapid and complete termination of Atlantic Nino and warm equatorial Atlantic SSTAs shortly after August. From December-May, SSTAs in the tropical North Atlantic (TNA) are typically cooler and SSTAs in the tropical South Atlantic (TSA) are typically warmer.
Precipitation observations: Precipitation over West Africa/sub-Sahel region (0-10N latitude) persists only through July-August. Reduced precipitation over northeastern South America from April-May.
Mode observations: -AMM develops in DJF and persists through MAM. Cold SSTAs in the equatorial Pacific along with La Nina conditions are exhibited in boreal winter.
Wind observations: Positive northeasterly wind anomalies in TNA and positive northwesterly wind anomalies in TSA during MAM.

Persistent
Years: 1963, 1973, 1984, 1987, 2010, 2016, and 2019
SSTA observations: Strong SSTAs observed in the Atlantic Nino area and warm equatorial Atlantic SSTAs that continue through the end of the year.
Precipitation observations: Precipitation is enhanced over northeastern South America September-December but exhibits reduced rainfall in this region from January-May.
Mode observations: Strong Pacific El Nino events during the preceding boreal winter are typical.
Wind observations: Weak trade wind anomalies in both hemispheres from December-May. Increased southwesterly wind anomalies located directly off the west coast of Africa reduces coastal upwelling (reinforcing Atlantic Nino).

 
Early onset
Years: 1988, 1995, 1998
SSTA observations: Gradual development of equatorial warm SSTAs starting in January but begin to dissipate as early as March. Southwest Africa develops warm SSTAs in DJF. Cooler SSTAs are common in TNA from December-May. Positive SSTAs are confined to the eastern equatorial Atlantic region.
Precipitation observations: Increased precipitation is typically not observed over West Africa/sub-Sahel region before July, and especially between the months of January-April. West Africa/sub-Sahel region exhibits increased precipitation anomalies between the months of July-August. South America experiences enhanced precipitation from April-May.
Mode observations: Strong Pacific El Nino events during the preceding boreal winter are typical.
Wind observations: Persistent interhemispheric wind anomalies from December-May.

Late onset
Years: 1949, 1951, 1968, 1981, 1993, and 2018
SSTA observations: A sudden and late development of warm equatorial SSTAs that begin in May and peak in June. Warm SSTAs persist through much of boreal summer in the Atlantic Nino and equatorial Atlantic region.
Precipitation observations: Enhanced precipitation rates are observed over West Africa and the sub-Sahel region from July-October. Neutral precipitation rates over northeastern South America are observed from July-October. Reduced rainfall over the Sahelian region (10-20N latitude) is reduced during June-September (i.e., a weakened West African monsoon during boreal summer).
Wind observations: Neutral wind anomalies are typical from December-May.

Anomaly composites

SSTAs


Precipitation Rates


500mb Heights


Mid-level RH


Zonal 10m Winds


meridional 10m winds


Omega 200mb Velocity Potential

[Category5Kaiju]

For those more interested in the Atlantic equatorial mode (or Atlantic Nino), I've broken down the four main varieties (early-termination, persistent, early-onset, late-onset; there are 4 mixed-signals as well but for brevity sake will not include those) with descriptions/observations and various anomaly composites. The anomaly images include SSTAs, precipitation rates, 500mb heights, mid-level relative humidity, zonal 10m winds, meridional 10m winds, and omega 200mb velocity potential. This is broken into seasonal outlooks: (1) December, January, February (DJF); (2) March, April, May (MAM); (3) June, July, August (JJA); and (4) September, October, November (SON). First, here is a description/observations of each of the four major types of Atlantic Nino:

Early termination
Years: 1974, 1991, and 1996
SSTA observations: Rapid and complete termination of Atlantic Nino and warm equatorial Atlantic SSTAs shortly after August. From December-May, SSTAs in the tropical North Atlantic (TNA) are typically cooler and SSTAs in the tropical South Atlantic (TSA) are typically warmer.
Precipitation observations: Precipitation over West Africa/sub-Sahel region (0-10N latitude) persists only through July-August. Reduced precipitation over northeastern South America from April-May.
Mode observations: -AMM develops in DJF and persists through MAM. Cold SSTAs in the equatorial Pacific along with La Nina conditions are exhibited in boreal winter.
Wind observations: Positive northeasterly wind anomalies in TNA and positive northwesterly wind anomalies in TSA during MAM.

Persistent
Years: 1963, 1973, 1984, 1987, 2010, 2016, and 2019
SSTA observations: Strong SSTAs observed in the Atlantic Nino area and warm equatorial Atlantic SSTAs that continue through the end of the year.
Precipitation observations: Precipitation is enhanced over northeastern South America September-December but exhibits reduced rainfall in this region from January-May.
Mode observations: Strong Pacific El Nino events during the preceding boreal winter are typical.
Wind observations: Weak trade wind anomalies in both hemispheres from December-May. Increased southwesterly wind anomalies located directly off the west coast of Africa reduces coastal upwelling (reinforcing Atlantic Nino).

 
Early onset
Years: 1988, 1995, 1998
SSTA observations: Gradual development of equatorial warm SSTAs starting in January but begin to dissipate as early as March. Southwest Africa develops warm SSTAs in DJF. Cooler SSTAs are common in TNA from December-May. Positive SSTAs are confined to the eastern equatorial Atlantic region.
Precipitation observations: Increased precipitation is typically not observed over West Africa/sub-Sahel region before July, and especially between the months of January-April. West Africa/sub-Sahel region exhibits increased precipitation anomalies between the months of July-August. South America experiences enhanced precipitation from April-May.
Mode observations: Strong Pacific El Nino events during the preceding boreal winter are typical.
Wind observations: Persistent interhemispheric wind anomalies from December-May.

Late onset
Years: 1949, 1951, 1968, 1981, 1993, and 2018
SSTA observations: A sudden and late development of warm equatorial SSTAs that begin in May and peak in June. Warm SSTAs persist through much of boreal summer in the Atlantic Nino and equatorial Atlantic region.
Precipitation observations: Enhanced precipitation rates are observed over West Africa and the sub-Sahel region from July-October. Neutral precipitation rates over northeastern South America are observed from July-October. Reduced rainfall over the Sahelian region (10-20N latitude) is reduced during June-September (i.e., a weakened West African monsoon during boreal summer).
Wind observations: Neutral wind anomalies are typical from December-May.

Anomaly composites

SSTAs
https://i.imgur.com/BCIsyX0.png

Precipitation Rates
https://i.imgur.com/OVhAKYa.png

500mb Heights
https://i.imgur.com/qe4Lasa.png

Mid-level RH
https://i.imgur.com/k6A6gGN.png

Zonal 10m Winds
https://i.imgur.com/mgApW38.png

meridional 10m winds
https://i.imgur.com/x02UFFA.png

Omega 200mb Velocity Potential
https://i.imgur.com/nRk9zBS.png

Damn that was a very informative and useful post.

[Shell Mound]

 https://twitter.com/AndyHazelton/status/1415669244658806787

[cycloneye]

For those more interested in the Atlantic equatorial mode (or Atlantic Nino), I've broken down the four main varieties (early-termination, persistent, early-onset, late-onset; there are 4 mixed-signals as well but for brevity sake will not include those) with descriptions/observations and various anomaly composites. The anomaly images include SSTAs, precipitation rates, 500mb heights, mid-level relative humidity, zonal 10m winds, meridional 10m winds, and omega 200mb velocity potential. This is broken into seasonal outlooks: (1) December, January, February (DJF); (2) March, April, May (MAM); (3) June, July, August (JJA); and (4) September, October, November (SON). First, here is a description/observations of each of the four major types of Atlantic Nino:

Early termination
Years: 1974, 1991, and 1996
SSTA observations: Rapid and complete termination of Atlantic Nino and warm equatorial Atlantic SSTAs shortly after August. From December-May, SSTAs in the tropical North Atlantic (TNA) are typically cooler and SSTAs in the tropical South Atlantic (TSA) are typically warmer.
Precipitation observations: Precipitation over West Africa/sub-Sahel region (0-10N latitude) persists only through July-August. Reduced precipitation over northeastern South America from April-May.
Mode observations: -AMM develops in DJF and persists through MAM. Cold SSTAs in the equatorial Pacific along with La Nina conditions are exhibited in boreal winter.
Wind observations: Positive northeasterly wind anomalies in TNA and positive northwesterly wind anomalies in TSA during MAM.

Persistent
Years: 1963, 1973, 1984, 1987, 2010, 2016, and 2019
SSTA observations: Strong SSTAs observed in the Atlantic Nino area and warm equatorial Atlantic SSTAs that continue through the end of the year.
Precipitation observations: Precipitation is enhanced over northeastern South America September-December but exhibits reduced rainfall in this region from January-May.
Mode observations: Strong Pacific El Nino events during the preceding boreal winter are typical.
Wind observations: Weak trade wind anomalies in both hemispheres from December-May. Increased southwesterly wind anomalies located directly off the west coast of Africa reduces coastal upwelling (reinforcing Atlantic Nino).

 
Early onset
Years: 1988, 1995, 1998
SSTA observations: Gradual development of equatorial warm SSTAs starting in January but begin to dissipate as early as March. Southwest Africa develops warm SSTAs in DJF. Cooler SSTAs are common in TNA from December-May. Positive SSTAs are confined to the eastern equatorial Atlantic region.
Precipitation observations: Increased precipitation is typically not observed over West Africa/sub-Sahel region before July, and especially between the months of January-April. West Africa/sub-Sahel region exhibits increased precipitation anomalies between the months of July-August. South America experiences enhanced precipitation from April-May.
Mode observations: Strong Pacific El Nino events during the preceding boreal winter are typical.
Wind observations: Persistent interhemispheric wind anomalies from December-May.

Late onset
Years: 1949, 1951, 1968, 1981, 1993, and 2018
SSTA observations: A sudden and late development of warm equatorial SSTAs that begin in May and peak in June. Warm SSTAs persist through much of boreal summer in the Atlantic Nino and equatorial Atlantic region.
Precipitation observations: Enhanced precipitation rates are observed over West Africa and the sub-Sahel region from July-October. Neutral precipitation rates over northeastern South America are observed from July-October. Reduced rainfall over the Sahelian region (10-20N latitude) is reduced during June-September (i.e., a weakened West African monsoon during boreal summer).
Wind observations: Neutral wind anomalies are typical from December-May.

Anomaly composites

SSTAs
https://i.imgur.com/BCIsyX0.png

Precipitation Rates
https://i.imgur.com/OVhAKYa.png

500mb Heights
https://i.imgur.com/qe4Lasa.png

Mid-level RH
https://i.imgur.com/k6A6gGN.png

Zonal 10m Winds
https://i.imgur.com/mgApW38.png

meridional 10m winds
https://i.imgur.com/x02UFFA.png

Omega 200mb Velocity Potential
https://i.imgur.com/nRk9zBS.png

The best post of 2021 at Talking Tropics forum so far. This is what we want to see posted more often as in depth discussions is the best way to help the members understand with clarity the theme on hand. Keep these comming USTropics.

[USTropics]

Here is a breakdown of Atlantic activity for the above mentioned Atlantic Nino varieties. Warning though, the sample size is too small to really glean definitive information. Overall takeaway is we generally see above-average to active Atlantic seasons, especially if we remove seasons that exhibited a strong Pacific El Nino during boreal summer:

[Category5Kaiju]

Here is a breakdown of Atlantic activity for the above mentioned Atlantic Nino varieties. Warning though, the sample size is too small to really glean definitive information. Overall takeaway is we generally see above-average to active Atlantic seasons, especially if we remove seasons that exhibited a strong Pacific El Nino during boreal summer:

https://i.imgur.com/FLKXGmb.png

How many of those years were second-year La Nina years though? Given the likely and plausible direction w'ere headed in I decided to comb through the years past 1995 to see if any of those years were second-year La Nina years, and while I could be wrong, it looks like none of those years seem to fit that definition.

[AlphaToOmega]

Here is a breakdown of Atlantic activity for the above mentioned Atlantic Nino varieties. Warning though, the sample size is too small to really glean definitive information. Overall takeaway is we generally see above-average to active Atlantic seasons, especially if we remove seasons that exhibited a strong Pacific El Nino during boreal summer:

https://i.imgur.com/FLKXGmb.png

How many of those years were second-year La Nina years though? Given the likely and plausible direction w'ere headed in I decided to comb through the years past 1995 to see if any of those years were second-year La Nina years, and while I could be wrong, it looks like none of those years seem to fit that definition.

I believe 1996 was second-year La Nina.

[USTropics]

Here is a breakdown of Atlantic activity for the above mentioned Atlantic Nino varieties. Warning though, the sample size is too small to really glean definitive information. Overall takeaway is we generally see above-average to active Atlantic seasons, especially if we remove seasons that exhibited a strong Pacific El Nino during boreal summer:

https://i.imgur.com/FLKXGmb.png

How many of those years were second-year La Nina years though? Given the likely and plausible direction w'ere headed in I decided to comb through the years past 1995 to see if any of those years were second-year La Nina years, and while I could be wrong, it looks like none of those years seem to fit that definition.

1996 and 1984 would be the closest to a double dip La Nina:

[Category5Kaiju]

Here is a breakdown of Atlantic activity for the above mentioned Atlantic Nino varieties. Warning though, the sample size is too small to really glean definitive information. Overall takeaway is we generally see above-average to active Atlantic seasons, especially if we remove seasons that exhibited a strong Pacific El Nino during boreal summer:

https://i.imgur.com/FLKXGmb.png

How many of those years were second-year La Nina years though? Given the likely and plausible direction w'ere headed in I decided to comb through the years past 1995 to see if any of those years were second-year La Nina years, and while I could be wrong, it looks like none of those years seem to fit that definition.

1996 and 1984 would be the closest to a double dip La Nina:
https://i.imgur.com/70NRXVf.png

Ah yes that's right, 1996 was almost a La Nina but it was operationally a cool neutral year if using the "at least 5 consecutive 3-month anomaly of -0.5C or less" definition.

[USTropics]

How many of those years were second-year La Nina years though? Given the likely and plausible direction w'ere headed in I decided to comb through the years past 1995 to see if any of those years were second-year La Nina years, and while I could be wrong, it looks like none of those years seem to fit that definition.

1996 and 1984 would be the closest to a double dip La Nina:
https://i.imgur.com/70NRXVf.png

Ah yes that's right, 1996 was almost a La Nina but it was operationally a cool neutral year if using the "at least 5 consecutive 3-month anomaly of -0.5C or less" definition.

Of course the issue with using 1984 is the background SSTA state due to negative AMO:


Here is Atlantic activity where we had an Atlantic El Nino signature and filtering out —AMO years (any year between 1965-1995):

[AlphaToOmega]

As of now, SSTs in the Nino 3.4 region are expected to be below-average. The CFSv2 forecasts weak La Nina conditions by August-September-October. An important thing to note is that none of the ensemble members forecast +ENSO conditions, meaning the chances of +ENSO are practically 0%.

[Category5Kaiju]

As of now, SSTs in the Nino 3.4 region are expected to be below-average. The CFSv2 forecasts weak La Nina conditions by August-September-October. An important thing to note is that none of the ensemble members forecast +ENSO conditions, meaning the chances of +ENSO are practically 0%.
https://i.postimg.cc/ZqM0TfJ2/nino34-Sea.gif

If that verifies and a weak La Nina does come to fruition...all I am going to say is buckle up.

[SFLcane]

Oh oh I am starting to see something resembling a +AMO trend over the last couple weeks.

[Shell Mound]

Reanalyses are a poor dataset to use for SST. It's best to use a dataset that is designed for ocean temperatures.

NOAA OI SST maps show that of the five years I mentioned that had Atlantic Niños and a flip from -AMM to +AMM by peak season, two (2008 and 2019) had July MDR SSTs that were slightly warmer than 2021 to date, and three (1996, 1999 and 2003) were cooler. Note that I use a broad definition of the MDR (10 to 20N and 20W to 90W).

https://i.ibb.co/hfp645Z/oisst-anom-14d-tropatl-2021071300.png
https://i.ibb.co/MgH9Gz0/oisst-anom-28d-tropatl-2019073000.png
https://i.ibb.co/YkvCkkY/oisst-anom-28d-tropatl-2008073000.png
https://i.ibb.co/56KtkCj/oisst-anom-28d-tropatl-2003073000.png
https://i.ibb.co/P5TTM9t/oisst-anom-28d-tropatl-1999073000.png
https://i.ibb.co/8jYhz2c/oisst-anom-28d-tropatl-1996073000.png

The main problem, then, is that July 2021 to date seems to be much cooler in the MDR and have more of a -AMM/-AMO than any of the years that you mentioned.

https://i.ibb.co/FBsRY5j/Ska-rmavbild-2021-07-15-kl-13-43-25.png
https://i.ibb.co/w4rVwLG/Ska-rmavbild-2021-07-15-kl-13-42-30.png

Clearly, 2021 has more of a hurdle to overcome in the AMM/AMO department than any of the other years to date. The -IOD/-ENSO could help somewhat, however.

Thank you for clarifying. Of the five years mentioned, the three that featured a cooler MDR to date ultimately yielded intense long-trackers such as Bertha, Edouard, Fran, Hortense, and Isidore (1996); Cindy, Floyd, and Gert (1999); and Fabian, Isabel, and Kate (2003). In particular, Edouard, Floyd, Gert, Fabian, and Isabel were all at least ≥ 125 kt at their respective peak intensities, and either Edouard or Floyd or both may have briefly attained Cat-5 status. Storms such as these belong to the same class as other intense CV long-trackers like Ivan (2004), Igor (2010), and Irma (2017)—several of which have been notorious “I” storms. Interestingly, the years that featured a cooler MDR than 2021 to date ended up with more intense activity in the MDR than did the two years that were slightly warmer. Additionally, the years that were cooler than 2021 to date ended up with more seasonal ACE (in the range of 166 to 177) than the years that were warmer. Given that 2021 will likely feature -IOD/-ENSO during ASO, the likelihood of a suppressed EPAC should further act to enhance the MDR for long-trackers. We could easily see multiple long-tracking majors in the MDR during ASO, in light of the years mentioned above. An enhanced MDR + projected steering currents favouring peninsular FL and the western Gulf → potentially significant trouble for portions of the CONUS and the southwestern Caribbean. If one takes into account “unofficial” indicators such as this—that happen to reinforce the “official” ones mentioned in this thread—then we could see multiple Cat-4+ threats to portions of the CONUS and Caribbean during ASO. A blend of 1943, 1945, 1949, 1961, 1996, 1999, and 2003 yields some rather unpleasant outcomes, as the following illustration of Category-2+ cyclones from those seasons suggests:



Note that the favoured regions of impact are the western Gulf Coast (principally TX), the SW Caribbean, southern peninsular FL, and eastern NC.

[cycloneye]

Oh oh I am starting to see something resembling a +AMO trend over the last couple weeks.

https://i.postimg.cc/Z5YRS0kh/1626-BBEF-177-E-41-B1-8-D88-EBE9-DD6568-C3.jpg

Hi Adrian. What are those signs that you are seeing?