Q&A of the Day – The Relationship Between Saharan Dust & Hurricanes
Each day I feature a listener question sent by one of these methods.
Email: brianmudd@iheartmedia.com
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Today’s Entry: Brian, I’ve noticed that you’ve been providing a daily update on the status of Saharan dust that you hadn’t previously provided along with an update on the tropics. Is it that you feel it’s especially important this season that you’ve chosen to report this way or is it just a change in presentation? The related reporting that I’ve heard discussed has suggested that Saharan dust is typical for this time of year but that it abates later in the season.
Bottom Line: There have been a few times throughout the year I’ve briefly discussed the topic of the importance of this year’s Saharan dust plume in influencing the Atlantic hurricane season. However, it was about two years ago that I most extensively covered the topic. In my story “Climate Change & A Quiet Atlantic Hurricane Season“ I pointed out this: At the forefront of active hurricane predictions has been the topic of climate change. And specifically warmer temperatures, and especially warmer oceans, resulting in increasingly active hurricane seasons. This is logical. It’s a fact that warmer waters are more conducive for tropical development – hence why hurricane season occurs when it does. But there’s a big ‘ole fly in the climate change = ever more hurricanes argument. It’s not analytical. And it’s been on my radar for over two years.
You might have noticed we seemingly have had more Saharan Dust clouds flying over South Florida. It’s not your imagination, we have. I had been researching this because my wife Ashley has asthma and the increasing Saharan Dust activity has meant she’s had to change inhalers, use them more often, and frequently pops Zyrtec. As part of my research into the Saharan Dust I came across a Harvard study in 2020 entitled Climate change affects Saharan dust storms. The lead line says it all: A new groundbreaking study shows that warming planet will make dust storms more intense in the Mediterranean and the Atlantic. Now, without diving into all the specs of the study, the bottom line is this. The past couple of years we have seen a marked increase in Saharan Dust clouds and Harvard’s researchers offer extensive evidence that rising temperatures/climate change is behind it. Few things act as a greater hurricane repellant than massive dust clouds across the entire Atlantic (crossing over into the Gulf).
Last year, when we swung into the El Nino weather pattern during hurricane season, Saharan dust wasn’t as prominent of a factor as the dust wasn’t often making its way here. But this year, as we’ve once again been shifting back to a La Nina weather pattern, the dust has been steadily flowing from coast to coast (Africa to the Americas) almost as though it’s been on a conveyer belt. I suggested this would be the case in my Top 3 Takeaways on April 22nd when I said...Not so fast. If you’re looking for potentially good news, consider this note from The Weather Channel about the upcoming hurricane season that we’ve been told could be “explosive” in terms of its activity. It could be a case of Saharan dust to the rescue. There’s been an unusually high level of Saharan dust kicked up into Europe in recent months due to the impact of last year’s El Nino cycle. While we’re losing the benefit of El Nino in terms of mitigating hurricanes this year, we may be gaining a tailwind of Saharan dust from it. As winds continue to shift further in this direction from Africa as we approach summer, that dust will being making its way towards us. Right now, it looks as though it could continue at unusually high levels through much of the hurricane season. Dry air and dust are a great combination for keeping tropical development at bay. If that happens this season just may not be so “explosive” after all. That is precisely the reason July has proved to be as quiet as it's been (with no tropical development during the month and none expected during the remainder of it) despite what has been predicted to be one of the busiest seasons in recorded history.
According to NOAA’s recent observations, the Atlantic has had about 50% less moisture in the atmosphere with the extensive, consistent, and potentially historic, Saharan dust clouds compared to the typical Atlantic atmosphere. As the Saharan dust has gone, the hurricane season has gone this year. The two early season storms to develop were in the western Gulf of Mexico away from the impact of the Saharan dust layer. It’s common for the pre and early season storms to develop close to land as was the case with those two. Then there’s the one that got away. Hurricane Beryl set records for being the earliest category 4 and 5 storm in history as its devastating effects played out in the southern Atlantic as its strength allowed for multiple landfalls that eventually brought it to the United States. The key for Beryl’s development was that it started out in the southern Atlantic and stayed there, outside of the Saharan dust layer. That may be a key for what we could see going forward this hurricane season and into the future. On that note...
Just Wednesday a new study entitled: Leading role of Saharan dust on tropical cyclone rain-fall in the Atlantic Basin was published in Science Advances and highlighted by Stanford University. Among the studied conclusions was this: Surprisingly, the leading factor controlling hurricane precipitation is not, as traditionally thought, sea surface temperature or humidity in the atmosphere. Instead, it's Sahara dust. Without getting in the weeds of the research the main takeaways were these. Saharan dust has become the single biggest factor in whether tropical formation takes place and how much rain is concentrated in storms that do form.
Warmer temperatures have led to more Saharan dust being sent into the atmosphere. Where there’s Saharan dust it’s unlikely that there will be significant tropical development regardless of how warm water and air temperatures may be. When and where there isn’t Saharan dust however, it’s likely there could be increased developmental activity and stronger storms more regularly. For now, there’s no end in sight to a high level of Saharan dust activity, and with continued high temperatures around the world this summer that’s likely to continue to be the case in coming weeks. For that reason, August, historically the second busiest month of hurricane season, could produce below average activity during what was predicted to potentially be the busiest season in history. The dust is the key this year, and given the warmer average global temperatures, potentially in future years as well. When it’s in the atmosphere at the levels we’ve seen, we should be free from development in the tropics. If and when it’s not around – that’s when it’s time to look out because the activity will be elevated, and those storms will be stronger as was the case with Beryl.