My 3rd and final Atlantic hurricane season update/outlook.

This will go into my thoughts and analysis on the upcoming Atlantic Hurricane Season. I will go over the factors that look to make this a very active season.

Part 3 is going to go into more depth on what I perceive to be the major risk for the 2020 hurricane season.  

The assumptions behind this forecast are (a) the persistence of the current North Atlantic sea surface temperatures (NAO) including the Maine Development Region (MDR), (b) the development of mild El Nino Southern Oscillation  (ENSO) being currently neutral and heading for negative conditions by late summer and early fall 2020, and (c) climatological mean conditions for the NAO that looks to be in place for fall winter 2020-2021.

The outlook makes the assumption you’ve read my first two installment of 2020s outlook. If you haven’t read them:

Part 1 can be found here

Part 2 can be found here

June 1^st marks the beginning of the 2020 Atlantic Hurricane Season. But, for the sixth consecutive year, the Atlantic Hurricane Season saw an early start.  The end of the season is November 30^th. So, we will have a long time to get through.

NOAA will release their official 2020 Atlantic hurricane outlook on the 21st at 11 am. Interested in seeing how different it will be from what I've posted. 

Tropical Storm Arthur:

What was to become Arthur, was a wave of low pressure moving over the Florida Straits on May 14 and 15 where it caused flooding across southern Florida and the Keys. On may 16^th the wave became Tropical Depression 1. Six hours later TD1 was upgraded to Tropical Storm Arthur. Arthur moved north northeast just missing the Outer Banks of North Carolina on the morning of May 18^th. Arthur curved out to sea, and was labeled a post tropical cyclone on May 19^th.  Arthur was a short-lived tropical storm. As of May 19^th, Colorado State University shows Arthur has an accumulated cyclone energy (ACE) index value of 2.0.

What is ACE? ACE is calculated by added the tropical cyclones wind speed through its life cycle. The sum of a season is the total ACE each Tropical Cyclone accumulated. The seasons ACE is based on the number, strength and duration of all the tropical cyclones during the season.

Years that are important to consider:  

The years in the Atlantic Basin that saw the most hurricanes (listed in order) 2005, 2010, 1969, 1995, 1950, 1933, 1887, 2017, 2012, 1998, 1916, 1893,1886, 1878, 1870.

The years in the Atlantic Basin that saw the most named storms (listed in order) 2005, 1933, 2012, 2011, 2010, 1995, 1887, 2019, 1969, 2017, and 1936.

The ten most active hurricane seasons (based on ACE values) in the Atlantic Basin, are (listed in order) 1933, 2005, 1893, 1926, 1995, 2004, 2017, 1950, 1961, and 1998. Each of these seasons saw ACE index values of 181.8 or higher.

The most active hurricane seasons in the Atlantic, since the satellite era (based by ACE index). (ranked 10 to 1) 2010, 1996 and 1969 tied for 8^th, 2003, 1999, 1998, 2017, 1995 and 2004 are tied for 2^nd, 2005.

Note before the satellite era there could have been tropical cyclones that escaped notice.

My analog seasons are 1933, 1952, 1953, 1959, 1995, 1996, 1998, 2003, 2005, , 2008, 2010 and 2017. But based on current conditions I also have to consider 2007 and 2013 as analogs (anti-analogs if you will) Out of the ten most active seasons, five are part of the analog seasons for this 2020 hurricane outlook.  Also, something to take note of, the years 1933, and 2017 saw named storms in May. The years 1933, 1995, 2005, and 2017 saw named storms in June.

Out of the seasons that had the highest number of hurricanes, only 1998 failed to produce at least one storm by the end of June.

When looking at the satellite era the hyperactive seasons 2005, 2008, and 2017 had cool Springs and had no El Nino.

If you look at all these seasons, many of the same years are seen repeatedly. That’s because patterns and teleconnections matter.

This year has a lot of similarities to many of these active and in some cases hyperactive seasons.

Teleconnections:

NOAA Coral Reef Watch

Tropical Tidbits

Tropical Cyclones require warm ocean temperatures to form. Looking at the charts, we see the Sea Surface Temperature (SST) in the Gulf of Mexico (GOM) are well above average. They also show much of the rest of the Atlantic has above average SST.

So how did we get here?

The 2019-2020 winter was fairly lackluster across much of the eastern CONUS. One of the major reasons for that, was the North Atlantic Oscillation (NAO) and its cousin the Arctic Oscillation stayed positive for the majority of the winter. So, with the predominate Southeast ridge over much of the East Coast, there were no real blockbuster storms.  The result of that is the water off the East Coast of the U.S. had plenty of time to warm up, and warm up it has.

Then during the 2^nd half of March, the AO and NAO went negative resulting in blocking high pressure to setup over Greenland.  This redirected the jet stream, and caused an predominate trough with a northwest flow. This allowed colder air to finely enter the pattern here in the CONUS. The below average temperatures went through April into the first part of May. But now the pattern has flipped, thus allowing for ridging to develop over the eastern U.S.  The teleconnections are signaling that from here forward, we should see predominate ridging once again over the eastern U.S.  The cool spring hasn’t really reduced the SST off the East Coast. So here we are, with a perfect SST pattern to produce plenty of tropical mischief. 

 The Pacific:

At this time the El Nino Southern Oscillation (ENSO) is still neutral. It is still likely that a weak to moderate La Nina will form later this year. Another factor that leads me to believe we will see a La Nina this year is the Indian Ocean Dipole (IOD). Many times, we see a La Nina form the year after a positive IOD, and last year we saw one of the most intensely positive IODs on record La Nina produces less wind shear in the Atlantic, which often leads to more and stronger tropical cyclones. We also have a positive Atlantic Multidecadal Oscillation (AMO) that is ongoing.

The MJO is signaling a ridge here in the East, once we get into summer. Many of the high impact years with landfalling tropical cyclones, had a very similar pattern.  The JMA is showing a lot of support for the MJO staying primarily in phases 2,3,4, which are the favorable phases needed for an active season. Phase 2 and 3 would increase the threat to the East Coast.

The JMA and the CFSv2 do support a favorable pressure pattern in the Atlantic.

The Atlantic:

The SST anomalies across much of the Atlantic, including the MDR are running roughly 1 F-2 F above average.

With the warm SST in the GOM and off the East Coast, we will have to be on the lookout for the possibility of explosive development, remember Michael.

The pattern that looks to be setting up, should allow the SST anomalies in the Atlantic Basin to get even warmer.

Cape Verde systems could be a concern this season. Warm SST and lower wind shear will make it easier for tropical waves to move off the West Coast of Africa and make it all the way across to the western Atlantic. Cape Verde hurricanes take there name from the Cape Verde Islands a few hundred miles off the West African Coast. 

I believe we will see several tropical cyclones track west of or over Bermuda, coming close to or even impacting the U.S. East Coast. The Mid Atlantic and New England are going to be at a higher risk for impacts this season.

The Euro Seasonal is showing a June, July August precipitation pattern that is along my idea of a real threat to the East Coast this season .

WeatherBell Analytics

Impacts:

A big Bermuda High will most likely set up by mid-summer. This will help steer the tropical waves westward. Where it sets up, will be factor in if it influences tropical cyclones to head into the Gulf or up the Eastern Seaboard. In 2005 the Bermuda High expanded south and east, which helped steer tropical cyclones into the GOM rather than up the East Coast or going out to sea. 2005 was considered a neutral ENSO season.  During La Nina there is greater chance for tropical cyclones to track into or along the East Coast. With the odds for a mid to late season La Nina developing in the Pacific, we will have to keep that possibility in mind. The Northeast/New England is long overdue for a hurricane strike. So, while there is no guarantee New England will see a landfalling tropical cyclone in 2020. But y’all have to keep the possibility in the back of your head, giving the likelihood of a very active season ahead.  

Florida and the Southeast Coast could have a busy season.  I think the Gulf is going to be another hot spot for development this season

The setup to have hurricanes impacting the East Coast of the CONUS, are above average pressure over the north Atlantic off the New England and Mid Atlantic coast. This would allow for lower average pressure off the Southeast Coast, Caribbean, into the GOM. The lower pressure areas would have more upward motion (lift). The same upward motion needed for thunderstorms holds true for hurricanes as well.

Here are the areas we're going to have to pay a lot of attention

. 

My call for the Atlantic Basin is that it will be hyperactive and one of the most active in history. 20-30 named storms, 9-14 hurricanes, 4-8 will become major hurricanes (Cat 3 or better). Ace index is going to be between 150 and 190.  I expect to see at least a few U.S. landfalls, some of them most likely will be major. Those along the Central and East Gulf Coast could see a very active season. The Mid Atlantic Region and Northeast will also see an increased likelihood of tropical cyclone impacts, with at last a couple of landfalls very possible.

  

The hyperactive season I’m forecasting doesn’t mean any storms will make landfall on the U.S (2010 is a good example). But the high number of tropical cyclones and the idea of above average homegrown activity, does greatly increase the odds. Regardless if this is an active season or not. It only takes one hurricane to bring devastation and loss of life. So, my advice is to be ready and prepare a plan just in case something comes your way.

That's it, hope you enjoyed my thoughts.