TS Isaac forms and is a threat to the US
TS Isaac has formed in the C ATL. He has 40mph winds, pressure of 1006mb, and is moving W at 18mph per the latest NHC advisory. I was at first TD9 and has been steadily organizing. Earlier when aircraft recon was investigating TD9 they found TS force winds so the NHC named TD9 TS Isaac. Isaac's formation brings the number of TS's this year to 9 which is above average. Isaac's satellite appearance has been steadily improving over the past 6 hours. Shear has lessened which is allowing convection to cover the center. Pressure has slowly been dropping with the convection increasing. While Isaac is a large storm his tropical storm force wind field is very small. This will change as he is expected to continue to strengthen. Isaac is currently competing with an area of convection to his south, he is still moving a little too fast, and is battling some dry air. This is preventing him from really taking off. But with shear decreasing and his forward speed slowing some dry air is becoming less of an issue. The forecast for Isaac is pretty tricky right now and there is a big ? mark as to where he will go. Any wobble can affect his intensity/track as he could go over Hispaniola/Cuba, just to the north, or just to the south. Models have been somewhat trending toward a S FL landfall right now but consistency isn't there for a serious call. looking at the latest steering map Isaac should continue W to WNW day or so before going NW due to a trough. Then this is where the models break apart. The ECWMF, which usually does great except for most of this year, takes Isaac into the GOM and intensifies it to a major hurricane. While the GFS, the other really reliable model, takes Isaac into S FL. But the GFS ensemble members take him all over the map. This is why there is no set in stone track for now. Once again looking at the steering map and forecast of the trough and Bermuda high, I think Isaac will make somewhat brief landfalls in Haiti and Cuba and the get pulled NNW and possibly brush FL and then make a final landfall between Jacksonville, FL to the SC/NC border. As for intensity, I think Isaac will hit Haiti as a 80mph hurricane and then weaken back to a TS due to hand interaction. Then Isaac will move NW and come close to Miami, FL before either moving inland some or staying offshore. Either way Isaac should go more N and make intensify to a cat2/3. I think a Savannah, GA to Charleston, SC area for landfall as a cat2 is probable. Anyone from the Leeward Islands to PR to Hispaniola/Cuba to FL and the rest of the SE US coast needs to watch Isaac as he is still unpredictable right now. This not an official NHC forecast and anyone looking for the official forecast or is making a life or death decision needs to go to the NHC for that. My forecast track for Isaac and a satellite view can be seen below. This blog will have a new home at my website weathergrab.com but will still remain seen on WU, come check it out. I'll have an update on Isaac and 96L tomorrow.