The area of focus for tropical cyclone activity for the next two weeks (and possibly the rest of the month) is going to be the Eastern Pacific, with Invest 96E a possible long range Hawaii threat. The remnants of Tropical Depression Four have lost organization since yesterday and regeneration has become very unlikely. In addition, Saharan Dust and a Suppressed Kelvin Wave is expected to limit any development of African tropical waves in the near future.

East Pacific: Eugene continues to weaken, Invest 96E very close to tropical depression status – and a possible long-term threat to Hawaii

Hurricane Eugene weakened to a tropical storm late Monday night and has continued to weaken today as it moves into progressively cooler waters. As of 2:00 p.m. PDT (5:00 p.m. EDT) Tuesday, Eugene was centered near 21.7°N 120.0°W, and was moving northwestward at about 9 mph. Maximum sustained winds were 45 knots (50 mph) with an estimated minimum pressure of 1001 mb. Eugene is currently over sea surface temperatures of 23°C (73.4°F), which is typically too cool for tropical cyclone formation. Eugene is also entering a drier, more stable environment as it moves northwestward. This should soon cause Eugene’s remaining deep convection to dissipate, and Eugene is expected to degenerate into a remnant low tomorrow when it becomes completely devoid of deep convection. Eugene is not a threat to land, other than causing high surf along the Baja California Peninsula.

In addition to Eugene, Invest 96E was designated in the East Pacific and has rapidly organized today. Some banding features have developed, and deep convection has been persisting for most of the day. The National Hurricane Center (NHC) gives 96E a 90 percent chance of development within 48 hours and five days. 96E is very close to tropical depression status and will likely be classified as Tropical Depression Six-E at 8:00 p.m. PDT (11:00 p.m. EDT). Model support for the development of 96E is strong. 96E is expected to take a more westward track than previous East Pacific storms this year, and is likely to eventually emerge into the Central Pacific basin. Global models predict that this system could be in the vicinity of the Hawaiian Islands in about ten days. This system has the potential to strengthen into a hurricane before it encounters the cooler waters of the Central Pacific basin, which typically limits strong hurricanes from affecting Hawaii.

Dry air limiting regeneration of TD Four and development of new tropical waves in the Atlantic

Dry air has limited the development of both the remnants of Tropical Depression Four, as well as the tropical wave in the eastern Atlantic that the GFS previously predicted to become a significant hurricane. None of the most recent GFS, ECMWF, CMC and UKMET model runs develop either of these systems. Most of the deep convection associated with both systems has diminished today, and tropical cyclone formation is not expected. The unfavorable conditions that limited development are likely associated with an unfavorable Kelvin Wave which has increased wind shear and dry air across the Atlantic basin.

The GFS model totally failed at predicting the genesis of the tropical wave, while the ECMWF model picked up on the unfavorable conditions much sooner. The wave has now been removed from the NHC’s Tropical Weather Outlook. Interestingly, the ECMWF model was actually the first model to predict development of the wave, but eventually dropped it shortly after the GFS began to show development. The GFS model predicted the development of a tropical cyclone in the eastern Caribbean for at least 16 runs in a row, while the new GFS Parallel model showed very little development. The GFS Parallel model is expected to replace the current GFS on July 19. I personally think this is a great upgrade and will have much less in the way of “ghost storms” in the Atlantic basin.

It should be stressed that the activity in the East Pacific and inactivity in the Atlantic is very typical of the month of July, and is not an indicator that the upcoming Atlantic season is going to be inactive. The East Pacific averages three to four named storms, two hurricanes, and one major hurricane for July. In contrast, the Atlantic averages one named storm for the month of July and a hurricane every two or three years, with a major hurricane very rare in the month.  Last season, the East Pacific had seven named storms form in the month of July, while the Atlantic had none. Both seasons ended up above the long-term average.

I will be back for an update tomorrow on 96E, which appears to be the only imminent tropical cyclone in the near future. 96E will likely be upgraded to Tropical Depression Six-E, perhaps even Tropical Storm Fernanda, by the time of the next post.