Tropical Storm Dorian -- The first Cape Verde Storm

Tropical Depression 4 - later Dorian

Over the next 8-10 weeks disturbances from West Africa will increase in intensity as they emerge from the coast every 3-5 days.  By the middle of August, it is possible that every 1 out of 3  disturbances will develop into a tropical depression, storm or hurricane as it moves across the Atlantic.  Some fraction of these will become major hurricanes.  Throughout the summer thus far the steering currents for tropical cyclones have been been oriented to carry storms from east to west.  Whether this pattern will continue is uncertain, but if it significant fraction of these tropical cyclones may threaten the Caribbean, Central America, Gulf of Mexico, Eastern US seaboard and Bermuda.
Some of these disturbances will cause flash flooding and wind damage before leaving the African continent threatening life and property.

When I look at all of the data, it is still difficult to know if the genesis of Dorian is a sign of things to come.  The dust coming from the Sahara has been plentiful making the overall environment unfavorable for tropical disturbances to develop into tropical cyclones.  The next 10 days or so will tell much about the month of August.

Cape Verde storms as they are often called form in August because the waters have warmed, the African Easterly Waves are more intense and dust retreats to the north.   When this happens, they can pose a threat to the people of the Cape Verde Islands-- especially the capital (Praia).

Tropical Cyclone Dorian is expected to continue west over the next 5 days.

5 day track of Tropical Storm Dorian

But as you can tell, unless it is picked up by a trough, it will continue to move west with an aim on the Bahamas, the keys and Florida.  The GFS forecast has it turning north and possibly threatening the East Coast but it is much too early to tell and the skill of the models are not great for tropical systems 144 hours out. 

The early projections were 13-20 storms.  The next few weeks will tell if that is an accurate call, but I expect the waves to amplify as they move across West Africa.  The waters will be warmer and but the flow over the western atlantic will become more complicated, with vertical shear and mid-latitude troughs having a greater influence on the strength and direction of westward moving tropical disturbances.   
But for reference, in
2005 there were 27 named storms - by July 25th there were 6 named storms - today we are at 4
2008 there were 17 named storms - by July 25th there were 4 named storms- today we are at 4
2010 there were 19 named storms - by July 25th there were 2 named storms- today we are at 4
2011 there were 18 named storms - by July 25th, there were 3 named storms- today we are at 4
2012 there were 19 named storms - by July 25th there were 4 named storms- today we are at 4


So if there is going to be a busy season, we are on par with other busy seasons and should not let our guards down.  Remember.. Hurricanes are the deadliest and most destructive forms of storms because of their scale, power, various forms of destruction (wind, flooding, storm surge) and duration. 

Stay tuned,  the Cape Verde season has kicked off.