Hurricanes & Heat

Eastern Pacific Hurricane Parade Continues; Record Ocean Heat Energy in the Atlantic

By: Jeff Masters and Bob Henson , 3:04 PM GMT on July 18, 2016

The Eastern Pacific’s unending parade of tropical cyclones continues. The latest member of the show is Hurricane Estelle, which got its name Friday night. Joining the party Tropical Storm Agatha started on July 2 have been Category 4 Hurricane Blas, Category 2 Hurricane Celia, Category 3 Hurricane Darby, and soon-to-be Category 1 Hurricane Estelle (Estelle was a high-end tropical storm with 70 mph winds at 11 am EDT Monday.) This puts us well ahead of climatology: the Eastern Pacific usually does not see its fifth named storm until July 22, its fourth hurricane until August 12, and its second major hurricane until August 19. An average season has 15 named storms, 8 hurricanes, and 3 major hurricanes.

Figure 1. VIIRS visible satellite image of ex-Hurricane Celia, Hurricane Darby, and Tropical Storm Estelle taken on Sunday afternoon, July 17, 2016. Image credit: NASA.

Frank and Georgette on the way?
In their 8 am EDT Monday Tropical Weather Outlook, NHC identified two more areas of possible tropical cyclone formation in the Eastern Pacific off the Pacific coast of Mexico. They gave 2-day and 5-day odds of development of 0% and 20% to one area, and 0% and 50% to the other. Both the European and GFS models show the potential for these areas of concern to become Tropical Storm Frank and Tropical Storm Georgette by late this week or early next week–though the models are not as gung-ho about developing these systems as they were for Agatha, Blas, Celia, Darby, and Estelle. The two potential new storms are expected to take a track to the west or west-northwest away from or parallel to the coast Mexico. The July record for named storms forming in the Eastern Pacific is seven, set in 1985, according to NHC hurricane scientist Eric Blake. If we get a Tropical Storm Georgette this year, that would tie the July record.

The Atlantic remains quiet–but beware of this year’s ocean heat content!
As is usually the case when the Eastern Pacific is active, the Atlantic is quiet. This inverse correlation in activity occurs because the conditions over the Eastern Pacific driving this July’s bounteous activity–surface low pressure and rising air–creates a compensating area of sinking air over the tropical Atlantic. This sinking air creates surface high pressure and dry weather–the antithesis of conditions needed for tropical cyclone formation. There are no tropical cyclone threat areas in the Atlantic to discuss today, and none of the reliable models for tropical cyclone formation is predicting development during the coming five days. Don’t expect to see much activity in the Atlantic until the Eastern Pacific’s burst of activity slows down. When we finally do get the surface low pressure, rising air, low wind shear, plentiful low to mid-level moisture and an African tropical wave needed to spawn an Atlantic hurricane, watch out. Record to near-record levels of heat energy are in the Atlantic in the Caribbean, Gulf of Mexico and waters surrounding the Bahamas (Figure 2), exceeding even the heat energy that was available during the notorious Hurricane Season of 2005. This year’s high levels of ocean heat content in the Atlantic increases the odds of dangerous rapidly-intensifying major hurricanes if the other conditions needed for intensification are present.

Figure 2. Total oceanic heat content (called the Tropical Cyclone Heat Potential, or TCHP) in kilojoules per square centimeter (kJ/cm^2), for July 15 for the years 2005 – 2016. TCHP was at near-record or record values over much of the Caribbean, Gulf of Mexico, and waters surrounding the Bahamas in July 2016. TCHP in excess of 90 kJ/cm^2 (orange colors) is commonly associated with rapid intensification of hurricanes. Image credit: NOAA/AOML.