Dry air Impacts on Senegal Rain

So the question that we struggle with is how did this situation come about??  It is a bit technical, but anytime you have a factor that last more than a few weeks, there is a large scale pattern that is at work.  Below I have a few examples of satellite based rainfall movies of how the dry air near the coast is disrupting precipitating system.

Case 1 July 23-24

This is a line of convection that formed during the evening and moved towards the coastline.  Under normal conditions, this type of storm would definitely reach Dakar with heavy rain.  The opposite happens in this case where the observations show that dry air is locked in 200 meter.


Case 2 (Squall line from Mali
July 31 - August 1

In the second case, a relatively strong squall line came across Mali and entered eastern Senegal during the early morning hours.  At 0600 UTC (2 AM US east coast)  the picture show rain rates and the squall line entering eastern Senegal.  But the dry air is still locked in Senegal.  Here is the movie of the line today.

The good news is that even Dakar, did receive some rain this afternoon. But the situation
needs to be watched.