Isaac is now a Tropical Storm, but is expected to become a hurricane within 48 hours, possibly a Category 2 hurricane by the time it reaches the U.S. mainland (which looks more likely with each passing hour).
Isaac is still an entry level Tropical Storm with winds gusting over 50 mph, but sustained just in the 40+ category range. Barometric pressure is only slowly falling, so a rapid intensification in the next 12 hours seems unlikely. But some slow strengthening is likely. Here is the latest forecast track from the NHC.
U.S. models now bring Isaac up the West Coast of Florida.
The latest GFS run now brings Isaac up the west (Gulf) coast of Florida between Monday and Wednesday of next week (with a much greater risk from Naples and Sarasota to Tampa), more in line with the European (ECMWF) model.
Officials with the GOP Convention are hanging on every update from the National Hurricane Center. The convention is slated to start August 27th in Tampa. http://www.washingtonpost.com/national/distant-tropical-threat-includes-florida-possibly-during-next-weeks-gop-convention/2012/08/21/8bab6d1e-ebc8-11e1-866f-60a00f604425_story.html
The European (ECMWF) model
The European (ECMWF) model continues to push Isaac into the Gulf of Mexico, with a possible Louisiana or Florida panhandle landfall by Thursday or Friday of next week. The overall threat appears to be shifting from the east coast of Florida to the west coast of Florida, but the entire state will feel the wrath of Isaac early next week.
As you can see, where Isaac heads in the next 60 hours plus is still a “fluid situation”. Often these storms can have wobbles, something we have not seen yet. Upper level steering winds from the Atlantic Ridge to its north continue steering it west at around 16 mph. I personally like to mix in a little history into my weather forecasting for tropical system. Here is what the analog chart for Isaac looks like.
Notice how often storms that formed in the same area turned north just before Florida and then curved out to the Atlantic.
This far out is would be crazy to speculate on a storms exact path after 48 hours. Optimistically, I hope the trend of curving north will continue which would push it farther east from the Southeast U.S. by this weekend. For those in the Carolinas go about your normal day to day life, but do check in with us about this storm over the next few days. Because the track is so uncertain at this point, Chief Meteorologist Paul Douglas says “People from Galveston to New Orleans to Pensacola, Tampa and Miami need to stay alert and start thinking about their family’s hurricane plans.”
Meteorologist Rob Koch
Follow me on Twitter @RobKochWNTV