Hurricane season this year is expected to be above average, NOAA and others projects

The rest of the tropical season is also expected to be active -- maybe even extremely active -- according to over a dozen entities that forecast the seasonal tropical outlook.

"Nearly all seasonal projections that have been issued by various agencies, institutions and private forecasting companies call for this season to be quite busy," CNN meteorologist Taylor Ward says.

Almost all of the projections call for an above average number of hurricanes -- more than six -- for this season, which begins June 1.

Some are even calling for an "extremely active" season of more than nine hurricanes.

But perhaps the most anticipated forecast is the one from the National Oceanic and Atmospheric Administration (NOAA), which was just released Thursday morning. It calls for an above average season, making the consensus even stronger that the US is headed for an active season.

NOAA's official forecast calls for 13 to 19 named storms, six to 10 of hurricanes, and three to six major hurricanes (category 3 or higher). All of these numbers are above an average season of 12 named storms and six hurricanes.

If this year does end up being an above-average season, it will be the fifth year in a row. According to Gerry Bell, lead hurricane season forecaster with NOAA's Climate Prediction Center, this would break the previous record of four set back in 1998-2001.

This year the average forecast -- for all 13 groups that have submitted to Seasonal Hurricane Predictions -- is eight hurricanes and 17 named storms.

Typically, these early forecasts vary a little bit more.

"In general, the consensus between seasonal hurricane forecasts this year is greater than it has been the past few years," says Phil Klotzbach, research scientist in the Department of Atmospheric Science at Colorado State University

The conditions look favorable for an active season

There are multiple ingredients that forecasters and forecast models consider when generating a seasonal hurricane forecast.

One is sea surface temperatures (SST). These sea surface temperatures are just one of the ingredients needed to fuel hurricanes. The warmer the ocean, the more fuel available for the storms to tap into.

"Sea surface temperatures across much of the Atlantic are running well above normal and have been for the past few months," Ward says. "Since tropical systems feed off of warm sea surface temperatures, this could certainly lead to a more active 2020 Atlantic hurricane season."

"The current Atlantic sea surface temperature setup is consistent with active Atlantic hurricane seasons," says Klotzbach, "with the notable exception of the far North Atlantic, which remains somewhat cooler than normal."

Another consideration is El Niño. When El Niño is present, it reduces Atlantic hurricane activity due to increased vertical wind shear -- changes in wind speed and direction with height that prevent hurricanes from building.

"There is high confidence that El Niño will not inhibit hurricane activity this year," Klotzbach says.

Average conditions or even La Niña conditions create a more favorable environment for tropical storm development.

Most forecast models are pointing to neutral conditions or even La Niña conditions during the season.

NOAA says the El Niño Southern Oscillation is favored -- about a 60% chance -- to remain neutral through the summer. However, hurricane season includes all three of the fall months, so will the neutral conditions stay or change in the fall?

According to the new NOAA release, the El Nino Southern Oscillation (ENSO) conditions are expected to either remain neutral or to trend toward La Niña, meaning there will not be an El Nino present to suppress hurricane activity.

Also, warmer-than-average sea surface temperatures in the tropical Atlantic Ocean and Caribbean Sea, coupled with reduced vertical wind shear, weaker tropical Atlantic trade winds, and an enhanced west African monsoon all increase the likelihood for an above-normal Atlantic hurricane season. Similar conditions have been producing more active seasons since the current high-activity era began in 1995.

The outlier

There is one organization that is a slight outlier. The European Centre for Medium-Range Weather Forecasts, or ECMWF, is forecasting a normal to a slightly above normal season.

Everyone else is predicting an above average number of named storms this season.

The ECMWF seasonal hurricane forecast is derived from a count of vortices spun up by the model during the hurricane season, says Klotzbach.

"Different numerical models often agree on the overall situation, but differ in details of what they predict for drivers of hurricane variability," says Tim Stockdale, a principal scientist at ECMWF.

Each of the forecasting groups uses different techniques to develop its forecast.

One computer model, called NCEP, is showing a strong La Niña development, and also very warm sea surface temperatures in the Gulf of Mexico. Anyone using this model in its forecast would likely predict a higher number of storms.

"The ECMWF model has weaker La Niña development, and sea surface temperature anomalies in the Atlantic are weaker, so both of these factors might give the ECMWF model a less-strong hurricane season than forecasts using NCEP inputs," Stockdale says, referring to the National Centers for Environmental Prediction.

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He also notes that their calibration is based on 1993-2015, and does not take into account the last four years (2016-19), which have been more active.

Those same years, the ECMWF has predicted fewer hurricanes ahead of the season than were observed.

One of the challenges this year is the sea surface temperatures globally, says Stockdale.

There are a lot of unusual anomalies, and it is uncertain how they will play together.

Their forecast computer model can integrate these anomalies in a way past models can't.

"On the other hand, the models still suffer from various tropical biases that mean we cannot be certain that their calculated responses will be correct," Stockdale says.

These forecasts groups have been producing hurricane forecast for decades

Even though these forecasts aren't the official word from NOAA, they aren't something to pass off.

A few of them have been issuing hurricane forecasts long before NOAA. Colorado State University has been doing seasonal projections the longest of any group.

"CSU started their seasonal hurricane forecasts in 1984," says Klotzbach. Of the groups submitting their outlooks to the Seasonal Hurricane Predictions website, the one with the longest track record of forecasts besides CSU is WeatherWorks, which started issuing predictions in 1992.

The Cuban Met Service started issuing seasonal forecasts in 1996. NOAA didn't start its seasonal forecasts until 1998.

Other than Tropical Storm Risk, which also started in 1998, all other groups started their outlooks in 2000 or later.

They are likely correct but the forecasts could be wrong

There is a chance these forecasts could be wrong.

For example, if the tropical Pacific were to become warmer and the tropical Atlantic is colder than predicted, hurricanes would likely be fewer than anticipated. Alternatively, if a robust La Niña develops and the tropical Atlantic remains warmer than usual, the season could be even more active than these predictions suggest.

There is also a chance there is an active season and nothing hits the US coast.

"The best recent example of an extremely active season with no US hurricane landfalls is 2010," Klotzbach says. "That year, we had 12 hurricanes in the Atlantic basin and zero US hurricane landfalls."

Climatologically, about 30% of all Atlantic hurricanes make US landfall, he says.

So the odds of having 12 hurricanes and no US landfall is about 1 in 70.

"We always say that it only takes one big hurricane landfall to be a bad season," says Ward. "So all coastal residents should certainly be paying close attention and have their hurricane plan ready for the upcoming season."