Wednesday, August 22, 2012
Perhaps the biggest change at 11 a.m. was the uncertainty. It seemed as if the NHC's meteorologist were more certain of Isaac's track and intensity with the 5 a.m. advisory. Now one of the computer models predicts Isaac will be so weakened by a trip over the Dominican Republic that it will not respond to the atmospheric weakness and will drift westward into the Gulf of Mexico.
But the overall consensus still points to Florida. And forecasters say the intensity prediction, in effect, is a guess. It all depends on whether the storm crosses a lot of land before approaching Florida.
By the way, most computer tracks take the remnants into the Carolinas next Tuesday and Wednesday.
I'll be watching for the next update at 5 p.m. It also will be interesting to see what the National Weather Service's office in Greer says about next week, in its mid-afternoon update.
Earlier post (9:30 a.m.): Tropical Storm Isaac would get secondary attention most years, but it was the lead story on many network newscasts Wednesday morning, and for good reason.
Computer models are nearly unanimous in predicting Isaac will be over or near Florida by next Monday morning -- just in time for the start of the Republican National Convention. And it is expected to be a hurricane, possible Category 2, when that happens.
And if you extend the storm track a bit, and take into account the possible atmospheric steering patterns next week, it would appear as if the Carolinas will be in the path of Isaac's remnants.
First for the facts.
At 8 a.m., Isaac was a rather weak tropical storm, with top winds of 45 mph. It was centered about 200 miles east of the island of Guadeloupe, in the Lesser Antilles. Isaac was moving west at 19 mph and is expected to strengthen Wednesday and Thursday.
Tropical storm warnings are posted for the Lesser Antilles and for Puerto Rico and the Virgin Islands (both the U.S. and British). A hurricane watch is up for Puerto Rico and the Virgin Islands. And a tropical storm watch is hoisted on the north coast of the Dominican Republic.
The computers predict Isaac will strengthen into a Category 1 hurricane and cross part of the Dominican Republic, then pass over eastern Cuba. At that point, it will be Sunday night, and Isaac is then forecast to move into the very warm waters of the Florida Straits and approach the Keys with 90 mph winds.
Some computer models take Isaac up the Gulf Coast, providing a direct threat to the Republican National Convention in Tampa. Other models predict the storm will cross the center of the Sunshine State. And others take Isaac up the Atlantic coast.
To me, a bigger question is the effect of the mountainous Dominican Republic (10,000-foot peaks) on the storm. Those mountains could turn Isaac into tropical road kill. Then again, if the expected hurricane brushes past the island of Hispaniola, watch out!
I heard the mayor of Tampa talking this morning about evacuations and calling off the convention, which must be a horror scenario to Republican Party officials. But that kind of talk is very premature. A lot can happen between now and then.
What about the Carolinas?: Oh, yes, there's that issue.
By the time Isaac reaches Florida, it will be sucked north by a weakness between high pressure in the Atlantic and another system to the west. The storm will be moving generally northward. If you draw some lines, that takes the remnants across South Carolina and North Carolina next Tuesday and Wednesday.
In 2004, Hurricane Frances struck Florida and curved north, bringing a record-setting tornado outbreak to South Carolina, and some twisters into the Charlotte region. Frances also produced incredible flooding in the North Carolina mountains.
I noticed this morning that the local National Weather Service office is starting to take notice. In his morning discussion, meteorologist Neil Dixon mentioned the possibility that tropical rainfall could move into the western Carolinas sometime Tuesday.
And what about 96L? You might remember the other cluster of storms, following about 1,000 miles behind Isaac. It's still there, and it'll probably become a tropical storm sometime Wednesday afternoon.
However, all the computer models take that system northwest through the Atlantic, then curve it northward -- far, far east of the United States.
Posted by Steve Lyttle at 8:55 AM