Thursday, July 25, 2019

"Hurricane Outlook May Change For The Worse As El Niño Fades"

But what about the Saharan Air Layer?*
From Freightwaves via Benzinga:
El Niño is weakening, but this isn't good for those wanting an uneventful hurricane season. El Niño – warmer-than-normal sea surface temperatures (SSTs) in the central and eastern Pacific – is a primary atmospheric regulator of hurricane activity, and it typically suppresses the development of storms in the Atlantic basin. It's a potentially bad sign that El Niño is showing signs of fading just as the heart of hurricane season arrives.

The El Niño effect
A weakening El Niño in the coming months may lead to increased activity, according to the National Oceanographic and Atmospheric Administration's (NOAA) Climate Prediction Center (CPC). El Niño alters the atmospheric flow of winds around the world, resulting in high altitude wind shear, which hampers Atlantic tropical cyclone activity.

During El Niño, fewer hurricanes and major hurricanes (Category 3 or stronger) develop in the deep tropics from African easterly waves. NOAA officials said in early July that a transition from El Niño to a weaker neutral phase is expected in the next month or two and could last through fall and winter. The effect is so critical to hurricane patterns that NOAA's seasonal hurricane prediction puts a great amount of emphasis on the seesawing Pacific cycle.
Evolution of the 2019 hurricane season outlook. Source: Colorado State University
The latest outlooks from NOAA and Colorado State University's (CSU) Department of Atmospheric Science called for near-normal Atlantic hurricane activity due to predicted El Niño activity. CSU increased its predicted number of hurricanes and major hurricanes by just one since its original forecast in April. But if the El Niño effect ends sooner than expected, more hurricanes could develop from African easterly waves in the deep tropics during the months that are typically the busiest for the Atlantic season – August through October.

These systems potentially have a greater likelihood of becoming major hurricanes and of eventually threatening Caribbean islands and the U.S. The chances of a hurricane making landfall can increase substantially during a La Niña, or during a deteriorating El Niño like the one that has evidently just begun.
Impact on trucking and freight...

*From opening day of the 2019 season:
June 1, 2019
Re/Insurance: With Today's Start of the Official Hurricane Season, A Look At Various Forecasts
The most interesting factor at the moment, more interesting even than the SAL (Saharan Air Layer) if you can believe that, is the El El Niño/Southern Oscillation. 
(just kidding about the SAL, it doesn't really come into play until those long-haul Cape Verde storms start running later in the season)
As noted a couple weeks ago in "Hurricane Watch: Australia's Bureau of Meteorology Lowers Odds of Full-Blown El Niño":
Long time readers know the El Niño/Southern Oscillation, through a couple teleconnections influences the North Atlantic hurricane season. Stronger/longer El Niño tends to correlate with fewer hurricanes, La Niña tends toward more 'canes....
...Look for later hurricane season forecasts to add one or two more hurricnes than the earlier guesses.
The BOM is one of our big three public sources on ENSO conditions, along with Columbia Uni/IRI and the US. NOAA.
For El Niño Modoki situations Japan's Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is the go-to.
Finally, the comment thread on this NOAA page seems to be leaning toward a Modoki:...
And it's not just a less powerful El Niño that raises the chances for a more active hurricane season.
Should the above mentioned Modoki variation be the summer-of-2019 story we hark back to this 2009 post:
New Type Of El Nino Could Mean More Hurricanes Make Landfall
And a few days later: