19 August 2011

Is This Irene In The Making??

Posted by Dan Satterfield



Hires NWP model indicating a hurricane near Cuba in 5 days. WARNING- this is just one forecast from one model and it should only be used as one piece of information in a forecast; average errors of greater than 500 miles are the norm in 5 day NWP tropical system forecasts.

While Tropical Storm Harvey is approaching Honduras, the most interesting system in the tropics is called Invest97L, and it may be about to become Tropical Storm Irene. There are several numerical weather prediction (NWP) models today that are developing this wave into a strong tropical storm and a few into a hurricane. A word of caution here, the models do this rather frequently and are often wrong.

There is some good reason to believe they may be right this time, and one reason is as simple as the date; it’s late August and prime time for Atlantic hurricanes. 97L will be moving into an area of greater instability in the next 48 hours and the wind shear aloft (that can kill a tropical system) is very light. I suspect the folks at the NHC in Miami will be sending a plane to look at this system over the weekend.

For those who live along the coasts, this is a good time to review your hurricane plans and supplies…


The bigger the temperature difference between low and high levels, the more unstable the atmosphere is. This image from CIRA indicates that 97L will be moving into an area of greater instability shortly. Notice the higher instability around the windward islands.

Another strong tropical wave is coming off of the coast of Africa and it too has potential to develop. We are now in the season for the Cape Verde type storms that track across thousands of miles of warm water before making landfall. Stay tuned and I’ll post an update over the weekend.