Sunday, dusty Sunday...

[Coconuts]

On Thursday, the National Weather Service issued an advisory that a large cloud of Saharan dust would arrive today, and it certainly did. Here's a Spice Cam shot from yesterday; some dust, but still reasonably clear visibility. Note the relative contrast of Thatch Cay and Great Hans Lollik, a bit lower and to its right:

Saturday

Thatch Cay is a bit over four miles away; Great Hans Lollik is over twice as far, and as such provides a great way to quickly assess visibility.
Now look at the view this morning, with the dust having arrived:

Sunday, dusty Sunday

What a difference a day makes! Great Hans Lollik is now barely visible.
Fortunately, dust can leave as quickly as it arrives, either carried away by the trade winds, or washed out of the air by rain.

Here is a Virgin Islands News article on the NWS advisory:
http://virginislandsdailynews.com/news/ ... -1.1702010

As previously posted, a very handy five day forecast of Saharan dust is available here: http://forecast.uoa.gr/dustindx.php. If you click "Animate", and then "Play" at the top of the new page that loads, you can watch the five day forecast play out. The numbers are dust density in micrograms per cubic meter.

Oh, and here is a NASA image of a giant dust cloud leaving the west coast of Africa:

Huge dust storm

All the best,

Kevin

[Jeff&Cindy]

Played the animation. Trying to understand this a little better.

Is this fairly consistent from year to year, or is this 'season' worse than others (or normal)?

Is there a 'season' for this? Because I don't recall hearing about this during our visits to STJ (always in February)

[Coconuts]

Jeff&Cindy: Yes, there is definitely a "dust season", and coming in February, you would have always missed it. Waves of dust come and go, but tend to start showing up in mid April, and continue on and off until around mid September. That's not to say that you can't have great clear skies during the summer, just that you want to have blue ocean surrounding the VI on the animation, and not be in one of the darker brown patches. This season is pretty typical; as the two photos a day apart in the original post show, some days are dusty; others clear. The potential for dust can impact the views of distant islands, but on the plus side, rental rates are lower, and those "frigid", barely 80 F waters of February climb to as high as 87 degrees in mid to late summer.

I've posted to this effect before, but much of the very fertile soil of the Amazonian rain forest arrived over the millennia as Sahara dust. It is also thought to suppress hurricane development. Increasing levels of Sahara dust as that desert has become more arid are thought to be partly to blame for coral die-offs. And of course, the dust can affect people with asthma or other respiratory diseases.

[Edit: Here it is Thursday, and most of the dust from Sunday to Wednesday has left the territory:

Thursday

All the best,

Kevin

[54b]

Thank you, Kevin. Most helpful post on the Sahara Dust I've seen thus far.

Been going to STJ for several years and always in June. I never really noticed the dust until last June when we must have had a particularly "dusty week" because it looked like that picture from last Sunday most of the time we were there. Kind of bummed me out.

We're headed back in a few days and I've been paying attention to that tracker you linked. Looks like the dust will be a little less dense this time, so hoping for a few more blue sky days on this go round.

Thanks again.

[psufan]

54b -we visited around the same time as you last year and agree that the dust was a bit disappointing. We just got back before this last wave and other than a few hazier days, it wasn't nearly as bad as last year. Hope it moves in your favor this year too.

[54b]

Good to know, thanks, PSUFan.