cieldumort
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While a technical La Niña for the coming fall and winter is not a sure bet (forecast is about a 55-60% chance), even the cooler bias is useful in forecasting activity trends in the Atlantic basin for at least the rest of this year.
ENSO neutral conditions actually tend to be even somewhat more favorable for big-time banner years (2005, 2017, etc.) overall, but La Niña is very supportive of active to hyperactive Atlantic seasons.
Speaking just about the months of October, Octobers during La Niñas are usually about 50% more active than neutral - and October is right around the corner.
A few other things La Niñas can usually be counted on for: Increasing odds of sub-tropical cyclone formation, many of which go on to become fully tropical. Also, lowering of shear over the Caribbean, thus helping cook up and fuel deeply warm-cored tropical cyclones there.
This lowering of shear over the Caribbean heading into the back-half of this already hyperactive 2017 season raises some alarm bells, especially for the Yucatan, Cuba, Florida, the Bahamas, Georgia, the Carolinas, and Bermuda. Many late-season tropical cyclones that begin in the Caribbean go on to impact these areas. (See image below)
Dr. Ryan Truchelut recently touched on all this with a good article in the Tallahassee Democrat (Link).
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cieldumort
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Above: WSI Proprietary Atmospheric Index
Credit: Dr. Michael Ventrice @MJVentrice PhD in tropical meteorology
Meteorological Scientist with The Weather Company and IBM Watson
As is not at all just about ocean temperatures, but also very much about how the air above the ocean behaves, the WSI AEI product is informative, and has been showing 2017 in an atmospheric La Niña state all year.
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Keith B
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Quote:
"So what is this telling us?"
If that question is in reference to the AEI image above, the image shows the index values for the current year (2017) and years that WSI has determined to be analogs. It tells two main stories: 1) Per their methodology, the atmosphere has been in a La Niña state all year, and 2) There may be some similar (analog) years with 2017 (2005 among them, in the image above).
For potential influences a La Niña can have on Atlantic hurricane seasons, here are some sites worth reading:
Impacts of El Niño and La Niña on the hurricane season
La Niña, El Niño, and Atlantic Hurricane Damages in the United States
Wikipedia La Niña
Hope that provides some answers  - Ciel
Edited by cieldumort (Fri Sep 22 2017 01:17 AM)
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cieldumort
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Keith B
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Loc: FL, Orange County
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Quote:
Quote:
"So what is this telling us?"
If that question is in reference to the AEI image above, the image shows the index values for the current year (2017) and years that WSI has determined to be analogs. It tells two main stories: 1) Per their methodology, the atmosphere has been in a La Niña state all year, and 2) There may be some similar (analog) years with 2017 (2005 among them, in the image above).
For potential influences a La Niña can have on Atlantic hurricane seasons, here are some sites worth reading:
Impacts of El Niño and La Niña on the hurricane season
La Niña, El Niño, and Atlantic Hurricane Damages in the United States
Wikipedia La Niña
Hope that provides some answers - Ciel
-----
Thank you for the info Ciel.
--------------------
Keith Boyer N4TRN
Orange County ARES
Asst. Emerg. Coord. (AEC) Skywarn Orange County, FL
http://www.ocares.org/
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cieldumort
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cieldumort
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cieldumort
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cieldumort
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And still counting...
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cieldumort
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cieldumort
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2017 with yet another first. Amazing.
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cieldumort
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Here's how the season looked at the end of September*
* Post-season analysis has not been completed. One or more of the above cyclones may be adjusted up, or down (more possibly up - looking at Jose, others, as candidates)
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cieldumort
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Here's how Accumulated Cyclone Energy (ACE) during the current 2017 year-to-date* stacks up against entire prior hurricane seasons from 1950-
2017 is already in the Top 10 (#6 as of today), and would need to add 49 more ACE units to overtake the entire 2005 (Satellite era ACE record) Atlantic Hurricane Season. That's a lot, but there are still three months left in the year, and this season has the potential to run long (as did 2005).
* Post-season analysis has not been completed. One or more of the above cyclones may be adjusted up, or down (more possibly up - looking at Jose, others, as candidates)
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cieldumort
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Another data point very consistent with Active Eras. Not much doubt left anyway, but another stat worth noting.
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cieldumort
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cieldumort
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cieldumort
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Ophelia - adding to the amazing records set this year
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cieldumort
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Playing catch up with the Hyperactive 2017 updates. There have been so many..
On October 11, Ophelia became the 10th consecutive Atlantic hurricane, 'tying the all-time record set in 1878 and equaled in 1886 & 1893' - Dr. Klotzbach.
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cieldumort
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Surpassing 2005, already
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cieldumort
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Ophelia. Location, location, location.
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