As we discussed in Monday’s newsletter, August is a big month for the Atlantic hurricane season.
Tropical activity typically picks up markedly compared to June and July, especially by later in the month.
The two systems we’re monitoring this week in the Atlantic will stay out to sea, so today we’ll look ahead to factors influencing the Atlantic in the weeks ahead and what we might expect this August.
Sea Surface Temperatures
The Atlantic continues to shatter records for warmth this hurricane season. July was easily the hottest July on record across the typical hurricane breeding grounds – from the Atlantic main development region to the Gulf of Mexico.
A multitude of factors are driving the warmth, including much weaker than average trade winds and less Saharan dust in the skies above to catch the sunlight before it reaches the ocean.
Nothing appears in the cards to rein in the warmth this August, unfortunately, as trade winds stay weak and already sparse dust outbreaks taper off heading into September. Of course, water temperatures are only part of the story.
Wind Shear
Wind shear to tropical systems acts like pruning shears to garden hedges – it lops off budding thunderstorm tops before they can grow and organize.
The more shear, the better.
Wind shear has been a mixed bag so far this summer. In June, the shear was well below average in the Atlantic, but this July, shear was more typical and even above average through the Caribbean.
During El Niño years like this one, we’d expect wind shear to run high in the Atlantic. While July could be a bridge to higher shear in August from a strengthening El Niño, our extended range computer models suggest otherwise – advertising lighter wind shear into the latter half of August.
Dry and Sinking Air
Hurricanes thrive off soupy tropical air, so dry air can be a big impediment to development. So far this season, we’ve seen lots of sinking air in the Atlantic, especially through the western part of the Atlantic.
This sinking air tends to warm and dry out the atmosphere, putting the lid on developing storms. The sinking air we’ve observed is a hallmark of El Niño, so it’ll likely continue to plague the Atlantic into August. The drier air works in our favor, but is it enough to counteract the rising air from very warm waters lurking beneath?
Putting the Puzzle Pieces Together
With extreme warmth in all the hurricane hot spots and models forecasting relatively light wind shear heading deeper into August, the overall configuration looks to favor storm activity this month.
The big wildcard will be El Niño’s influence on the Atlantic – primarily from sinking air and wind shear not detected in our models.
For now, forecast models aren’t sniffing out anything too concerning in the next week or two, but we’ll keep our eye on the trends as the Atlantic hits its stride later this month.