Something strange is happening with the weather over the Atlantic ocean. When tropical storm Elsa sped from the open waters of the tropical Atlantic into Barbados sustained hurricane force winds of 74mph (65knots) buffeted the island and Elsa was upgraded to hurricane status. This would be no big deal in September, but Elsa is the earliest fifth tropical storm to form in the Atlantic. Moreover, it formed in the open waters of the Atlantic’s main development region. Conditions are usually unfavorable in this region in July because of wind shear and dry Saharan air air aloft.
Tropical storm Danny should not have formed at all. The National Hurricane Center pegged it as having a 10% chance of developing into a named storm, but it did. June storms usually form from disturbances in the deep Caribbean or from lows that develop off of frontal boundaries that dive into the Gulf of Mexico or the Gulf Stream region of the Atlantic. Danny formed from instability from a cold upper level disturbance, a weather development normally seen in September or October.
This early summer the subtropical subsidence high pressure areas, such as the Bermuda high and the Pacific high are north of there normal positions. The heat dome that usually forms over the Colorado Plateau in late June was displaced into the Pacific northwest. In effect, the tropics and subtropics have expanded this spring and early summer, with stunning impacts.
I just flew from the east coast to the west coast in what for me was record time. We had tail winds over Texas. Typically east to west flights encounter head winds from the west, but not yesterday. There has been a solid polar jet stream for late June and early July, but it’s tighter to the pole. What’s missing has been the high level westerly subtropical jet stream and the high level wind shear that’s normally seen over the Atlantic off the east coast of North America. Elsa is facing very light shear between the low level winds and high level winds. That’s very unusual for early July.
I just reviewed maps of ocean heat contents of the north Atlantic. The heat content has been very high since 2016. Each year shows variations, but the high heat content has led to elevated tropical storm activity since 2016. July 1 heat contents in 2016, 2020 and 2021 are surprisingly similar but this year there’s a little less heat in the tropics and a little more heat on the north wall of the Gulf Stream on it’s east side. The strong early start to this year’s storm season is not explained by more ocean heat in the tropics than last year or 2016.
It’s too early to tell what impacts Elsa might have on the continental United States and it doesn’t appear to be heading towards Puerto Rico or the Virgin Islands. Interactions with Hispaniola, Jamaica and Cuba are possible. Haiti and Cuba appear to be at greatest risk of a hurricane landfall.
What ever happens with Elsa, it’s time to prepare for another intense hurricane season along the Gulf and east coasts of the United States. Everyone living in the Caribbean needs to be storm ready. Atmospheric conditions have been exceptionally favorable for storm development so far this season. Given the high hurricane activity level we’ve seen since 2016, expect another intense peak of hurricane activity in late August, September and October.