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What a Difference a Day Makes!

PostPosted: Fri Oct 03, 2014 8:40 am
by Coconuts
On island for this lowest of the low season, and for the most part, the weather has been excellent. No storms in an exceptionally quiet Atlantic hurricane season, and only one day in two weeks that was a rain-out (and even that began with on and off sun). As recently as yesterday, the visibility was excellent; on Thursday, Vieques and Culebra were easily seen from Gifft Hill (45 miles), and on Wednesday I could even make out the southern slope of El Yunque on Puerto Rico - 65 miles away!

We awoke today to an entirely different panorama, as I had expected from a look at the University of Athens dust forecast. Here is a view from the deck at Coconuts on Thursday; my lens isn't wide angle enough to capture the whole panorama in one image, so French Cap to Great St. James isn't visible, or Great Cruz Bay, but the scene from St. Thomas to Great Hans Lollik is really nice and crisp:
Panorama Thursday.jpg
Panorama on Thursday

Now here is the same view, taken this morning (Friday). The dust plume rolled in overnight. I had noticed during the evening that the stars were all pretty faint.
Panorama Friday.jpg
Panorama on Friday

And here are the respective dust forecasts from the great site at the University of Athens (http://forecast.uoa.gr/dustindx.php):
Dust forecast Thursday.jpg
Dust forecast on Thursday; plume on the way

Dust forecast Friday.jpg
Dust forecast on Friday; plume has arrived

By the end of October, dust such as this will have mostly tapered off. From April to now, however, it is a bit of a dice roll as to the clarity on any given day. Fortunately, dust plumes can depart as quickly as they arrive.

Edit: While it has been known for some time that most of the soil in the Amazonian rainforest was transported from Africa as Sahara dust, and that the dust plays a role in discouraging hurricane formation, Sahara dust has recently won a new kudo. It appears, from recent research at the University of Miami, that the Great Bahama Bank and the Bahama islands came about due to fertilization of the sea water with iron-rich Sahara dust, which led to massive cyanobacteria blooms, which in turn produced the carbonate that makes up the bank and islands. Cool!
http://rsmas.miami.edu/news-events/pres ... mas-great/

All the best,

Kevin

Re: What a Difference a Day Makes!

PostPosted: Fri Oct 03, 2014 9:43 am
by betsyv
Hi Kevin,
We will be on island in the next few weeks. I will take the dust if it keeps away the rain....Of course if I could have none of either I'd be a very happy visitor.

We fell in love with the island last year and are bringing family this year, Hopefully it will all live up to the expectations I have built up in them... :D

Re: What a Difference a Day Makes!

PostPosted: Fri Oct 03, 2014 12:22 pm
by SamanthaL
I'm with Betsy, we will be on island for a week in 2 weeks. I'm really hoping the dust is gone by then, but will take it over rain!

That first picture is just GORGEOUS!

Re: What a Difference a Day Makes!

PostPosted: Fri Oct 03, 2014 1:05 pm
by Backtotheislands
Kevin, please keep us posted! I'm hoping the dust will dissipate by Wednesday or Thursday, but, like everyone else, prefer the dust to rain and storms!

Re: What a Difference a Day Makes!

PostPosted: Fri Oct 03, 2014 1:42 pm
by Coconuts
Betsy, Samantha, and BTTI: The U of A website dust forecast already goes out five days, so simply scrolling down to the bottom of the "Select Period" list just to the left of the dust map will let you see what is coming. Do note that they use the European standard for day and month; October 4th is "04.10.2014".

Better yet, simply click the "Animate" button below the "Select Period" list, and then "Play" on the new page that loads. This will animate the next five days of dust forecasts. Pay attention to the numbers on the dust clouds; low ones (under 10) can be barely noticeable. Above 20 begins to really affect the visibility. These numbers are micrograms per cubic meter.

Hope things clear up for your visit!

Edit: Samantha: Thanks for your comment on the first photo. I used no image enhancement; it really is that blue! FWIW, that's a Julie Mango to the right of the sundial, a banana plant to its upper left, a fruiting papaya at image center, and a key lime, Barbados cherry, and another banana plant on the far left.

All the best,

Kevin