NOAA Calls for Near-Average 2016 Atlantic Hurricane Season; Other Groups Go Bigger

In its first outlook for the 2016 Atlantic hurricane season, issued Friday, NOAA’s Climate Prediction Center is calling for near-normal activity as the most likely outcome. The NOAA outlook predicts a 70 percent likelihood of 10 - 16 named storms, 4 - 8 hurricanes, and 1 - 4 major hurricanes (Category 3 or higher on the Saffir-Simpson Hurricane Wind Scale). These numbers include Hurricane Alex, which developed in January over the northeast Atlantic. If we take the midpoint of these ranges, NOAA is calling for 13 named storms, 6 hurricanes, and 2.5 major hurricanes. This is very close to the 1981-2010 seasonal averages of 12 named storms, 6 hurricanes, and 3 major hurricanes. NOAA/CPC forecaster Gerry Bell stressed: “This is a more challenging hurricane season outlook than most because it’s difficult to determine whether there will be reinforcing or competing climate influences on tropical storm development.” NOAA is projecting a 30 percent chance of an above-normal season and a 25 percent chance of a below-normal season.

One factor that looks increasingly likely to push the system toward a more active season is the likelihood of weak to moderate La Niña conditions by late summer. La Niña favors hurricane development in the Atlantic by reducing the amount of vertical wind shear that tends to prevail over the region. The latest monthly NOAA/IRI probabilistic outlook, issued May 19, calls for a 70-75% chance of La Niña conditions by late summer/early autumn. Several other forecasting groups are now predicting a considerably busier-than-usual season, as detailed below.



TSR predicts an above-average Atlantic hurricane season: 17 named storms
The May 27 forecast for the 2016 Atlantic hurricane season made by British private forecasting firm Tropical Storm Risk, Inc. (TSR) is calling for a total of 17 named storms, 9 hurricanes, 4 major hurricanes, and an Accumulated Cyclone Energy (ACE) of 130 for the period June through December. This is a major shift from TSR’s April 9 forecast, which called for a near-average season with 12 named storms, 6 hurricanes, 2 major hurricanes, and an ACE of 80. The changes are the result of a trend toward negative North Atlantic Oscillation (NAO) conditions, which favor warmer peak-season waters in the main development region of the tropical Atlantic, as well as the increasing likelihood of La Niña.

CSU predicts a near-average Atlantic hurricane season: 13 named storms
A near-average Atlantic hurricane season is likely in 2016, said the hurricane forecasting team of Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU) in their latest seasonal forecast issued April 14. They called for an Atlantic hurricane season with 13 named storms, 6 hurricanes, 2 major hurricanes, and an Accumulated Cyclone Energy (ACE) of 93 (these numbers all take Alex into account.) The next CSU forecast is due on June 1, and will receive a lot of media attention--it will be their first seasonal hurricane forecast issued without Dr. Bill Gray's authorship, as he passed away last month. Our April 14, 2016 blog post has more on CSU's most recent forecast.

UKMET office predicts a slightly above-average Atlantic hurricane season: 14 named storms
The UKMET office forecast for the 2016 Atlantic hurricane season, issued May 12, calls for slightly above-normal activity, with 14 named storms, 6 - 10 hurricanes, and an ACE index of 125 occurring during the period June - November. In contrast to the statistical models relied upon by CSU, TSR, and (to a lesser extent NOAA), the UKMET forecast is done strictly using a dynamical global seasonal model, the Met Office GloSea5 system.

The Weather Company predicts a slightly above-average Atlantic hurricane season: 14 named storms
The April 27 forecast from The Weather Company is calling for a near-average Atlantic hurricane season with 14 named storms, 8 hurricanes, and 3 major hurricanes.

Penn State predicts an exceptionally above-average Atlantic hurricane season: 19 named storms
Here's a forecast worth paying attention to: the April 25 forecast made using a statistical model by Penn State's Michael Mann and alumnus Michael Kozar called for an extremely active Atlantic hurricane season with 19 named storms (expected range: 14 to 24). Their prediction was made using statistics of how past hurricane seasons have behaved in response to sea surface temperatures (SSTs), the El Niño/La Niña oscillation, the NAO, and other factors. The statistical model assumed that in 2016 the late-April +0.88°C departure of temperature from average in the Main Development Region (MDR) for hurricanes in the tropical Atlantic would persist throughout hurricane season, a moderate La Niña would form this fall, and the NAO would be near average. If no La Niña forms, their model predicts reduced activity: 16 named storms.

The PSU team has been making Atlantic hurricane season forecasts since 2007, and these predictions have done well, except for in 2012, when an expected El Niño did not materialize:

2007 prediction: 15 named storms, Actual: 15
2009 prediction: 12 named storms, Actual: 9
2010 prediction: 23 named storms, Actual: 19
2011 prediction: 16 named storms, Actual: 19
2012 prediction: 11 named storms, Actual: 19
2013 prediction: 16 named storms, Actual: 14
2014 prediction: 9 named storms, Actual: 8
2015 prediction: 7 named storms, Actual: 11

NCSU predicts an above-average Atlantic hurricane season: 15 - 18 named storms
The April 15 forecast from North Carolina State University (NCSU), called for an above-average Atlantic hurricane season with 15 - 18 named storms, 8 - 11 hurricanes, and 3 - 5 major hurricanes. They use a statistical model encompassing more than 100 years of past Atlantic hurricane activity to make their forecasts.

Coastal Carolina University predicts a near-average Atlantic hurricane season: 13 named storms
The May 7 forecast from Coastal Carolina University called for a near-average Atlantic hurricane season with 13 named storms, 7 hurricanes, and 3 major hurricanes.

Cuban Met service predicts a near-average Atlantic hurricane season: 12 named storms
The May 4 forecast from the Cuban Meteorological Service, INSMET, called for a near-average Atlantic hurricane season with 12 named storms and 7 hurricanes. The forecast is based on a statistical prediction model developed by Ballester, González and Pérez (2010).

Little change to 91L approaching the Southeast U.S. coast
There hasn't been a lot of change to the story of Invest 91L, which we detailed in a post put up at noon EDT on Friday. An Air Force hurricane hunter aircraft was in the storm Friday afternoon, and we'll wait to make a new post on 91L until the mission is complete.

Jeff Masters and Bob Henson