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bluewave

2011-2016 MDR Dry Air And Stability Issues

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Increase in 500 mb drying of the Tropical Atlantic basin became noticeable around 2011. This feature has been common since then during the 

June to September period. Numerous systems during the peak of the hurricane season have had issues with dry air. The 2011-2016 era has

experienced the driest air on record extending across the MDR region of the Atlantic and Caribbean. This dry air is a bit of a mystery

to forecasters with some theories revolving around tropical drying related to changes in the Hadley circulation.

 

A second unknown is what has been causing this dry air to relax during Octobers since 2011? This reduction in dry air for October

has resulted in an historic run of major October hurricanes. The strongest hurricanes of 2011, 2012, 2014, 2015, and 2016 have all

occurred during the month of October.

 

Strongest hurricanes of season since 2011 in October:

2011...Ophelia...Cat 4....940 mb

2012...Sandy.....Cat 3....940 mb

2014...Gonzalo..Cat 4....940 mb

2015...Joaquin...Cat 4....935mb

2016...Matthew..Cat 5....934 mb...Nicole second strongest of season

 

Record 500 mb dry air over Tropical Atlantic basin June-September 2011-2016

 

 

 

 

Relaxation of dry air October 2011-2016

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Interesting tidbit as usual Blue.  We know there is typically a 'secondary peak' of tropical activity in October (peak being around sept 10), but having our strongest storms of the year all coming in October is certainly not something we have seen recently. Do you know if there is anything in the tropical record that would show an equal period of time with the strongest Atlantic storms occurring in October?

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On October 14, 2016 at 10:36 AM, tdp146 said:

Interesting tidbit as usual Blue.  We know there is typically a 'secondary peak' of tropical activity in October (peak being around sept 10), but having our strongest storms of the year all coming in October is certainly not something we have seen recently. Do you know if there is anything in the tropical record that would show an equal period of time with the strongest Atlantic storms occurring in October?

While we had numerous hurricane seasons in the past with the strongest hurricane development in October, the amount of suppression during recent Septembers

is something that really stands out before the October rebound.

 

Here are some great stats from Phillip Klotzbach:

https://mobile.twitter.com/philklotzbach?p=s

Oct. 1-14 had produced more ACE than 1/1-9/30 in the Atlantic only once in the last century prior to this year (1962).

October 2016 has produced the most Atlantic major hurricane days in any October since 1893.
 
Hurricane #Matthew has produced more ACE in the first 5 days of October than all Atlantic TCs in Sept. of 2014 & Sept. of 2015 combined.
 
Atlantic ACE during September from 2013 thru 2016 is the lowest 4-year combined September ACE since 1911-1914
 
Atlantic TCs have generated 66 ACE units so far this month - the most on record (since 1851) between 10/1-10/16.
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Here are similar graphics to what was originally posted by Bluewave, in 2016. The graphics in the original post seem to have disappeared. The abnormally dry and perhaps abnormal downward motion (positive omega = downward motion) over the 6 yr period of 2011-2016 might help to explain the lack of strong Cape Verde type systems tracking across the MDR, for years.

VgKK4qG.png

yBcfHgy.png

 

 

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Is it just me, or has it actually been that SAL/Saharan dust/abundance of dry air is becoming more and more of a problem each year with tropical development.

 

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Plot Twist:  wouldn't it be something if it turned out climate change was causing drying in the Sahara which in turned was promoting a continuous existence of strong SAL that, in turn, was damping down the Atlantic basin.

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In the end, it may mean more boom and bust tropical cyclone activity with accumulated cyclone energy reductions in the Atlantic MDR when the Pacific Basin is in hyperdrive. This is my initial impression. I am also aware that the Sahara Desert was green during the HCO and Eemian. If climate change is the cause of MDR drying, then we should expect more changes going forward.

Food for thought, the Sahara is the source region for the Saharan Air Layer (SAL). Feel free to move this to the climate forum.

Sahara greening may intensify tropical cyclone activity worldwide

https://www.sciencedaily.com/releases/2017/06/170608073356.htm

journal.pone.0076514.g004

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Intriguing information.  It shows how changes in one part of the world affect the other as the planet seeks to achieve a new balance.  This might also explain the spike in Eastern Pac storms and the rise in intensity thereof.

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