Saharan Dust invasion

[Rocky Rascovich]

Greetings!
With this paltry, pathetic storm season starting to wind down, eyes start turning toward the tropics... and so far this season has been short of what has been expected. Thismorning I checked out the TPC's site and read that an unusually dense cloud of Saharan dust has started its trek across the Atlantic... This is not unusual for dust clouds to make it across the ocean this time of year... but if you look at the satellite link below....(this updates so you better look soon as of 1400gmt 7/23) this dust cloud is indeed thick... so thick that its supressing convection... and probably the usual warming at the surface.

I would love some feedback on why this phenomenon occurs every year... whats led to this particular event... and the eventual outcome of this season. I'm not a tropical weather expert... but I do agree that we will be signifigantly below last years numbers as far as named storms are concerned... SST's are a couple of degrees lower than normal in the central and eastern Atlantic... and there is talk amongst the more seasoned climotologists that an el nino may be on the horizon... which as you know, can supress tropical activity. Perhaps Jim Leonard and other tropical experts can chime in here. Below is the satellite link.

http://weather.msfc.nasa.gov/GOES/goeseastfull.html

Rocky&family

 

[Jim Leonard]

Rocky,
Us tropical fanatics have gotten a little spoiled after the 2004/2005 hurricane seasons. We have to remember first that the 2004 season did not really start until August 1st. 2005 was an extreme event one that we probably will not see anything similar for many hundreds of years in the future. There were 27 named storms which shattered the old record of 21 in 1933. According to reliable records there has been no seasons with more than 19 storms other than 1995 and 2005. The 2005 storm numbers even beat the western pacific which averages 30 tropical storms each year, something that has never happend before since records were kept.
The Saharan dust outbreak we see on satellite this morning is a common occurence during the late spring and summer. We here in south Florida see this junk come through after every tropical wave crosses our longitude especially from mid-June through mid-August. Later in the summer the tropical waves become more convective so less dust makes all the way across the atlantic. Also the chances the waves become tropical cyclones which helpes dispurse the dust.
The current dust outbreak is following a wave and vorticity center near latitude 15N and longitude 40W. The dust is usually associated with a cap much like we see on the plains. The eastern atlantic sst's are cooler especially before late August than the western atlantic so convective temperature is rarely reached unless the SST's are unusually warm or the system makes it to warmer sst's in the western part of the atlantic basin where the sst's are warmer.
One should remember historically some of the most distructive hurricanes come along after the 20th of August. July is normally a real quiet period during the season mainly the surface pressures are at their highest of anytime during the hurricane season.