Forecast Track About the Same, Isaac Has Passed Haiti

…Forecast track basically unchanged. Slowed a little. Projected northern Gulf landfall around 2 a.m. Wednesday on Florida Panhandle mostly likely between Pensacola and Panama City. “Skinny black line” officially lies near the Walton/Bay County line right now (for comparison purposes only – the cone of uncertainty stretches now from Slidell LA to Fort Lauderdale FL).

…Models are in pretty good agreement, with tracks tigghtly clustered around Destin to Panama City.

…Most of the intensity outputs from the models are in agreement as well. Isaac should be a category one hurricane at landfall.

…Isaac didn’t weaken much as it passed over the mountainous terrain of southwestern Haiti.  It lost 10 mph in intensity.

…Top winds are 60 mph. Advisory central pressure was estimated at 992 mb but an Air Force plane found a central pressure of 1000 mb at 5:39 a.m. Flight level winds were 68 mph, so intensity of 60 mph still is good.

…Now back over the water over the Windward Passage between Cuba and Hispaniola

…By noon CDT, the center will land in eastern Cuba. Moving northwest at 16 mph, the center should re-emerge over water by this evening over the Florida Straits. It will become a hurricane Sunday.

…Tropical storm conditions will begin in the Florida Keys Sunday morning with about an 11% chance there will be hurricane conditions of 75 mph with gusts to 90 mph Sunday afternoon.

…The center will cross the Keys (probably around Marathon) around 11 p.m. Sunday evening.

…Preparations need to be completed in Keys today. State of Emergency declared for Monroe County FL.

…Evacuations not ordered for Keys, but people in low lying areas and homeless people urged to go to shelters which are open. Good thing not having to evacuate, because weather is terrible this morning in Keys with storms all along the Overseas Highway. Severe thunderstorm warnings in effect for Keys around Key Largo this morning as well.

…The morning weather over South Florida this morning is because of that trough that is loving east over Florida.

…Isaac will spend Monday moving northwest over the eastern Gulf. It will intensify (most likely slowly, we hope) and should have top winds of 90 mph by late Monday evening when it will be about 90 miles west southwest of Tampa.

…Tampa will see tropical storm force winds by early Monday morning and will have them through early Tuesday morning.

…Hurricane warnings are in effect as far north as Fort Myers, but expect tropical storm warnings over nearly the entire Peninsula.

…Orlando will see tropical storm force winds at times on Monday.

…Isaac should slow and start a north northwest turn Tuesday morning as it makes its final approach to the coast.

Arrival of tropical storm force winds:
Apalachicola…late Monday evening
Panama City…shortly after midnight Monday night
Destin…around sunrise Tuesday

…Landfall should come around midnight Tuesday night, probably between Panama City and Destin.

Hurricane force winds will be felt over about a 75 mile wide area. Strong tropical storm force winds (greater than 58 mph) will be felt over about a 150 mile swath and tropical storm force winds (39 mph or higher) will be felt over a 275 mile swath.

…Hurricane warnings will likely be issued late Sunday or early Monday for the coast. On this track and size, and level of forecast uncertainty, the hurricane warning will likely run from Pensacola to Apalachicola.

…Conditions will start to deteriorate after midnight Monday night in the projected landfall area, so plan to get most of your preparations done Monday along the Gulf Coast across the Florida Panhandle.

…Could Isaac be stronger than forecast? Definitely and we will have to be ready for that. It is going to be a large hurricane, which is bad since its affects will be felt over a wide area. But large hurricanes don’t tend to intensify as fast. And being a little closer to Florida is probably in our favor. But it will have a feast of warm water to gorge itself on.

IMPACT ON CENTRAL ALABAMA
…If this track materializes, Isaac will spread heavy rain northward over Central Alabama late Tuesday night and Wednesday. Rain and storms will be likely on Wednesday. It will be quite windy, with winds averaging 30-50 mph with higher gusts. There could be a few tornadoes east of the track as well, but they should be of the small, short lived variety mainly.

HEAVY RAIN
There is a rift between the models as to the eventually track. The 0z GFS turned it quickly northeast into Georgia, affecting only Southeast Alabama with heavy rain. The 06z GFS takes a little more westerly track, still into Georgia, but affecting more of Alabama.

The European moves it slowly up into Mississippi, giving Central Alabama 1-2 inches of rain.

So, if the storm starts taking a more northeasterly track, as the GFS is suggesting by late Wednesday, most of the rain will fall east of I-65. We will just have to wait and see.

Category: Tropical