Friday, May 27, 2016

8 Things to Know About the 2016 Atlantic Hurricane Season

Jon Erdman
Published: May 26,2016

The 2016 Atlantic hurricane season is upon us.
One prominent suppressor of tropical activity is absent. Does that mean the recent stretch of relatively few U.S. hurricane landfalls will continue?
Let's step through some of the interesting changes and other items to watch this season.
(MORE: Hurricane Central)

1.) El Niño is Gone

As the 2015 hurricane season kicked off, a moderate El Niño was already in place, intensifying to the strongest El Niño since 1997 by late in the season.
Starting in late winter 2016, this previously record-tying El Niño fizzled rapidly.
Strong El Niños are known to produce strong wind shear – a large change in wind speed and/or direction with height that acts to either keep tropical cyclones from forming or rip apart any existing storms.
Last season, the only two named storms that tried to approach the Caribbean – Danny and Erika – both fizzled, thanks to the strongest wind shear on record since 1979 for that area, according to Colorado State University tropical meteorologist Dr. Phil Klotzbach.
(MORE: 2015 Hurricane Season Recap)

2.) More Named Storms Expected

Lacking the strong El Niño, it loads the dice toward an increased chance of tropical cyclones surviving into the Caribbean Sea, or forming there in 2016, particularly later in the season as El Niño disappears farther in the rear-view mirror.
This is just one factor weighing into a small uptick in the total number of named storms forecast by The Weather Company and Colorado State University.
(MORE: 2016 Hurricane Season Outlook)
As we've noted numerous times, tropical cyclone-suppressing wind shear and dry air can be, and have been, in place in the absence of El Niño in recent years.
Suffice it to say, the forecast is more uncertain this season.

3.) Landfall(s)? That's a Good Question ...

Named StormsHurricanesCat. 3+ HurricanesU.S. Hurricane Landfalls
1998141033
19834311
19738410
196611732
195810750
The table above shows Atlantic season statistics in five previous hurricane seasons following strong El Niños, using the El Niño intensity classification scheme from consultant meteorologist Jan Null.
As you can see, there's quite a spread, ranging from a record low four named storms in 1983 to 14 such storms in 1998.
The 1998 season featured seven U.S. landfalling tropical cyclones, three of which – Bonnie, Earl, and Georges – were hurricanes at landfall.
Despite only four named storms in 1983, two of those made U.S. landfall, including Cat. 3 Hurricane Alicia in southeast Texas.
This again illustrates the poor correlation between the number of named storms or hurricanes and landfalls.
And, regarding some seasonal landfall forecasts out there, we'll just let current National Hurricane Center Director Dr. Rick Knabb lay it out.


4.) Hurricane Apathy?

U.S. hurricane landfalls the last 10 years. Note: Sandy in 2012 is not shown since it officially made landfall as a non-tropical cyclone.
This is a concern every season, but the recent dearth of U.S. hurricane landfalls is in record territory.
First, it's been nearly two years since the last U.S. hurricane landfall, when Arthur grazed eastern North Carolina over the Fourth of July holiday in 2014.
Arthur has been the only U.S. hurricane landfall since Superstorm Sandy.
From 2006 to 2015, only 13 percent of Atlantic hurricanes have impacted the mainland U.S., according to Klotzbach – a record low for any 10-year period during the satellite era (since the mid-1960s).
Florida's decade-plus-long hurricane drought has been well-covered. Klotzbach also noted Texas has also gone over seven years since its last hurricane landfall (Ike).
Such long gaps in hurricane activity like the one we are seeing can lead to complacency among residents, and millions of new residents near the coast have likely never experienced a hurricane.

5.) Less Active Seasons Ahead?

Atlantic Multidecadal Oscillation from 1880 through February 2013.



























The North Atlantic Ocean undergoes sea-surface temperature changes lasting 20 to 40 years that have an influence on hurricane season activity, among other things.
The so-called Atlantic Multidecadal Oscillation shifted into a warmer phase beginning in 1995, which has been found to correlate to a higher number of tropical storms becoming strong hurricanes, but not necessarily to the number of tropical storms or low-end hurricanes.
Recently, however, Klotzbach, among others, have noted the AMO has trended toward the cooler phase since late 2014.
Given this is a "multidecadal" signal, it may still not be obvious yet that we have indeed shifted to a cool AMO phase this season, and we don't yet have the ability to predict when this will occur.
It'll be another variable to monitor that may have implications for the next several hurricane seasons.

6.) NHC Storm Surge Threat Map Live

Example of a storm surge forecast map from the National Hurricane Center.
(NHC Storm Surge Unit)
In most hurricanes, it's water – not wind – that claims lives.
Potentially the most prolific killer in a stronger hurricane is storm surge, a term used to describe the rise in water level above normal tide in coastal areas as the hurricane's wind pushes water ashore.
To more clearly communicate the danger, the National Hurricane Center has rolled out storm surge forecast maps which, instead of past forecasts relative to high or low tide, simply tell you how much water you can expect above ground level using a simple color code.
While the forecast doesn't include waves riding atop the surge, or any additional water rise from heavy rainfall or rivers draining toward coastal areas, it is meant to give you an idea of the threat in the simplest terms possible.
For more on this new product, check out the National Hurricane Center's writeup.

7.) Greater Inland Flood Threat For Some?

Ninety-day rainfall departures from average, in inches, over the South ending May 25, 2016, illustrating the wet southern Plains and Lower Mississippi Valley, but dry Southeast.





















One of the underrated dangers of tropical cyclones, no matter the intensity, is rainfall flooding. This, of course, can occur hundreds of miles inland from the coast.
Heading into the 2016 hurricane season, parts of Texas, Louisiana, Arkansas and west Tennessee have been soaked by one of their top 10 wettest springs on record. This included a deluge of over two feet of rain in March for parts of Louisiana, and what was described as the worst flooding since Allison in 2001 in the Houston metro area one month later.
Clearly, a landfalling tropical cyclone, particularly a slow-mover early in the season, could be disastrous for this area.

8.) New 'I' and 'T' Names

2016 Atlantic hurricane season names, with the new names replacing ones retired from 2010 denoted by red boxes. Alex is italicized since it was a hurricane in January, prior to the start of the season.
Atlantic and eastern Pacific tropical cyclone name lists typically repeat every six years, unless one is so destructive and/or deadly that a committee from the World Meteorological Organization, which selects the names, votes to retire that name from future lists.
(MORE: 2015's Retired Names | The Complete Retired Names List Since 1954)
In 2010, Hurricanes Igor and Tomas were retired, and are replaced in 2016 by "Ian" and "Tobias."
Igor was the most destructive hurricane in 75 years to hit Newfoundland in September 2010. Tomas was the latest-in-season hurricane on record to strike the Windward Islands, hammering St. Lucia with high winds, flooding and mudslides, while triggering additional flooding and mudslides in Haiti.
If you live where hurricanes and tropical storms threaten, you should be prepared every hurricane season, regardless of how long it's been since the last one, or what hurricane season outlooks say.
After all, it only takes one storm to turn any hurricane season into a disaster.
(MORE: Are You #HurricaneStrong?)
Jonathan Erdman is a senior meteorologist at weather.com and has been an incurable weather geek since a tornado narrowly missed his childhood home in Wisconsin at age 7.

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