2020 Indicators: SST's / SAL / MSLP / Steering / Shear / Instability / Sat Images

[BYG Jacob]

I knew the hand-wringing over SST anomalies would look silly.

[toad strangler]

I knew the hand-wringing over SST anomalies would look silly.

It really is one of the most remarkable phenomenons I've seen on this forum at least this year. WAY TOO MUCH emphasis on the smallest negative anomalies .... as if there were icebergs developing out there. Anyway ......

 http://twitter.com/DylanFedericoWX/status/1269246334357381121

[toad strangler]

 https://twitter.com/BenNollWeather/status/1269316874174595072

[BYG Jacob]

When even the Euro has the Atlantic being active...

[Kazmit]

I knew the hand-wringing over SST anomalies would look silly.

It really is one of the most remarkable phenomenons I've seen on this forum at least this year. WAY TOO MUCH emphasis on the smallest negative anomalies .... as if there were icebergs developing out there. Anyway ......

http://twitter.com/DylanFedericoWX/status/1269246334357381121?s=20

People sometimes forget that negative anomalies mean that water is cooler than normal, not that it is too cold for storms to form. Like, instead of 85 degree water, it's 82 degree water. It's still gonna be warm enough to support a hurricane!

[AnnularCane]

People sometimes forget that negative anomalies mean that water is cooler than normal, not that it is too cold for storms to form. Like, instead of 85 degree water, it's 82 degree water. It's still gonna be warm enough to support a hurricane!

I wonder if the deep blue colors might sometimes give the impression that the water is a lot cooler than it actually is.

[cycloneye]

When you see ECMWF having this, I do this.

 https://twitter.com/webberweather/status/1269433326726774784

[Shell Mound]

 https://twitter.com/AndyHazelton/status/1269440928940425223



 https://twitter.com/webberweather/status/1269446258323787777



 https://twitter.com/webberweather/status/1269444382408740868



 https://twitter.com/AndyHazelton/status/1269441129495306240

[Shell Mound]

Based on those tweets, the June ECMWF monthly output for September 2020 suggests a strong +NAO (hence stronger trades and higher MSLP over the MDR/Caribbean) and a lot of anticyclonic wave-breaking (AWB) due to a pronounced mid-oceanic TUTT over the central subtropical Atlantic. Note that the ITCZ is displaced well to the south of its typical location. This pattern also results in a cooler MDR vs. June 2020, including current conditions. The fact that the subtropical ridge is situated farther north due to the strong +NAO could also allow more storms to either a) curve out to sea or b) continue westward into Central America. Again, this is not a forecast, but a summary of the latest ECMWF forecast for September 2020. Nevertheless, the past several ECMWF runs have been rather insistent on cooling down the MDR/Caribbean by September 2020. How reliable is the long-range ECMWF for synoptic-level forecasting, e.g., in terms of the NAO?

[CyclonicFury]

June ECMWF seasonal calling for about 11 tropical storms from July onward, with ~5.5 hurricanes and ~85 ACE. Even with a La Niña and warmer than normal MDR, the ECMWF continues to predict below average activity. This signal would be worth considering more if not for the model's awful verification.

[StruThiO]

June ECMWF seasonal calling for about 11 tropical storms from July onward, with ~5.5 hurricanes and ~85 ACE. Even with a La Niña and warmer than normal MDR, the ECMWF continues to predict below average activity. This signal would be worth considering more if not for the model's awful verification.

[Shell Mound]

June ECMWF seasonal calling for about 11 tropical storms from July onward, with ~5.5 hurricanes and ~85 ACE. Even with a La Niña and warmer than normal MDR, the ECMWF continues to predict below average activity. This signal would be worth considering more if not for the model's awful verification.

What about the points that I raised above? The June ECMWF seasonal shows a rather unfavourable pattern in place by September. Why does it?

[CyclonicFury]

June ECMWF seasonal calling for about 11 tropical storms from July onward, with ~5.5 hurricanes and ~85 ACE. Even with a La Niña and warmer than normal MDR, the ECMWF continues to predict below average activity. This signal would be worth considering more if not for the model's awful verification.

What about the points that I raised above? The June ECMWF seasonal shows a rather unfavourable pattern in place by September. Why does it?

I'm not sure why the pattern looks unfavorable, but FWIW, the anomaly maps use a 1993-2016 climatology period which is mostly during the active era. The ECMWF seasonal Atlantic forecasts seemed more accurate before 2010, but have really struggled during the last four years. The model seems to have a major dry bias over Africa as I posted about a few weeks ago.

[Shell Mound]

June ECMWF seasonal calling for about 11 tropical storms from July onward, with ~5.5 hurricanes and ~85 ACE. Even with a La Niña and warmer than normal MDR, the ECMWF continues to predict below average activity. This signal would be worth considering more if not for the model's awful verification.

What about the points that I raised above? The June ECMWF seasonal shows a rather unfavourable pattern in place by September. Why does it?

I'm not sure why the pattern looks unfavorable, but FWIW, the anomaly maps use a 1993-2016 climatology period which is mostly during the active era. The ECMWF seasonal Atlantic forecasts seemed more accurate before 2010, but have really struggled during the last four years. The model seems to have a major dry bias over Africa as I posted about a few weeks ago.

I was referring to the fact that the past several ECMWF runs have been consistently cooling down the MDR by peak season and showing strong VWS (TUTT). Why?

[WeatherEmperor]

June ECMWF seasonal calling for about 11 tropical storms from July onward, with ~5.5 hurricanes and ~85 ACE. Even with a La Niña and warmer than normal MDR, the ECMWF continues to predict below average activity. This signal would be worth considering more if not for the model's awful verification.

What about the points that I raised above? The June ECMWF seasonal shows a rather unfavourable pattern in place by September. Why does it?

The Euro has been showing an unfavorable background state in the ATL for 2016, 2017, 2018 and 2019. It has been wrong for each of those years.

Conditions "can" be unfavorable, but it is almost impossible for these seasonal forecasts to predict that little tiny short window of opportunity that allows a TC to explode into a Cat 5 at the worst possible time ala Matthew 2016 and Dorian 2019 and Michael 2018 and the list goes on. It is these sudden, unexpected "nobody saw this coming" Cat 5 supporting conditions that come out of nowhere that scares people and the last 4 years are proof of that


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[cycloneye]

If the ECMWF is right, there will be increasing trades in MDR by June 15 that would cool some the waters. GFS also has strong Azores high of 1035 mbs.

[jconsor]

 https://twitter.com/cyclonicwx/status/1269717866477228036

[SFLcane]

 https://twitter.com/AlexLubbers2/status/1269803734621548544

[Shell Mound]

https://twitter.com/cyclonicwx/status/1269717866477228036

On the other hand, the EC suggests a significant -AMO trend by peak season, owing to a +NAO, and suggests a strong TUTT near the Lesser Antilles.

How reliable is the EC in terms of long-range synoptic and SST forecasts? We all know that the EC has a dry bias in regard to the WAM...

[cycloneye]

Shell Mound, I guess if the S2K poll was still open you would have changed the numbers (Again) from the 20/13/8 ACE: 260