African dust to thin next week

JACKSONVILLE, Fla. – The massive batch of dry dusty Saharan air smothering Jacksonville since Thursday is going to start thinning Monday.

The forecast is keeping it thick Sunday before upper winds begin to flush it southeast of our area Monday. You should expect bluer skies Monday and improving air quality.

Microscopic grains of desert sand lofted into the air rode across the Atlantic to Texas before whipping back across Florida this week. It usually thins out over the eastern Caribbean Sea before reaching Florida.

This one has been the thickest on record. The dust is suspended about 2-2.5 miles up and can extend down to a mile above ground. It does not accumulate on the ground like ash from a wildfire.

Puerto Rico saw their skies fill with dust, reducing visibility. Saharan dust typically causes beautiful sunsets yes, but it can also cause air quality alerts.

Dr. Sunil Joshi, an allergy and asthma doctor in Jacksonville, said the dust can have an unhealthy impact on those with respiratory concerns.

“If you have asthma, it can cause the classic asthma symptoms of coughing, wheezing, shortness of breath or chest tightness,” Joshi said.

Joshi suggests that if you start to feel unwell, you should go inside and close all windows to keep the dust out of your home.

“If you suffer with allergies or asthma in particular, I think people who have other respiratory conditions, including COPD (chronic obstructive pulmonary disease) or congestive heart failure also have to really be concerned about this too because it can certainly affect your lungs and decrease your ability to transfer oxygen to your bloodstream, which can become a major problem for people who suffer with chronic lung disease,” Joshi said.

You can always check your air quality before heading out by going to the Florida Department of Environmental Protection website and click on air quality.

Compared to islands around the Lesser Antilles or Puerto Rico the level of dust will not be as high over Florida. In fact it typically stays suspended in air currents in well above the ground according to WJXT Meteorologist Mark Collins. Trace amounts do reach the surface. He says the dusting over millions of years has resulted in coloring the soils throughout Florida with red hues from the small amounts of iron laced in the fallout.

The cloud of fine suspended sediments should be around Florida on Wednesday, enhancing the sunrise and sunsets. Vivid skies are enhanced by the dust scattering out all but the reddest hues when the sun sits low on the horizon.

Aesthetics aside, the dry sinking motions of the Saharan Air Layer (SAL) tends to suppress hurricane activity. Dust outbreaks typically occur every year during June and July before fading in early August, which is when hurricane frequency picks up.

The plume of brown colors on the GOES-East satellite show where the thickest areas of dust exist from the middle of the Atlantic back to the African coast.

The same Bermuda High that provides a steady onshore breeze typically during the Jacksonville summer also directs the dust westward.

Eventually, the transport ends late in the summer as the high shifts south and wetter tropical waves moving off of Africa rinse out the air.