…Hurricane Joaquin has rapidly intensified over the last 24 hours to a major hurricane…
…Imminent danger to the Bahamas / Concern increasing for the east coast of the U.S…
At 10 pm this Wednesday evening, Hurricane Joaquin was located about 90 miles east of San Salvador, Bahamas. Air force Reserve Hurricane Hunter aircraft indicate that maximum sustained winds have increased to 115 mph, and Joaquin is now a major / category 3 / hurricane.
Model guidance is in reasonably good agreement that the storm will move slowly southwest over the next 24 to 36 hours, bringing dangerous hurricane conditions to the following locations:
* Central Bahamas including Cat Island, the Exumas, Long Island,
Rum Cay, and San Salvador
* Northwestern Bahamas including the Abacos, Berry Islands,
Eleuthera, Grand Bahama Island, and New Providence, but excluding
Andros Island and Bimini
Joaquin is expected to turn toward the northwest and north Thursday night or Friday – and this is when the forecast turns tricky.
A strong band of mid-level winds currently extends from the Northern Rockies to the Central Plains. This jet segment is forecast to nose into the deep south, and eventually lead to a cut off low in the vicinity of southern Alabama by Friday afternoon. Most reliable guidance points to an interaction between the cutoff low and Joaquin, with an evolution that slings the hurricane northwestward and eventually westward into the Carolina coast. Should this scenario play out, the potential exists for a variety of dangerous weather – especially near and north of the eye location. The 18z GFS suggests that the westward movement of the hurricane will accelerate late Saturday and early Sunday. A quick westward motion would mean that the system will still be quite strong well inland, meaning an increased area of damaging wind potential. Of possibly greater concern would be flooding. Much of the Carolinas and Virginia have been experiencing flooding, and numerous flood and flash flood watches and warnings are currently in effect. The amount of rainfall that a hurricane would bring could lead to catastrophic flooding.
Now to the biggest forecast issue. The ECMWF is and has been forecasting Joaquin to stay well offshore, with very little impact to the east coast. This is important because the ECMWF has proven to be a very reliable model when it comes to tropical storms and hurricanes. It is best known for its handling of Hurricane Sandy in 2012.
From the latest discussion from the National Hurricane Center:
Confidence in the details of the forecast after 72 hours remains
low, since we have one normally excellent model that keeps Joaquin
far away from the United States east coast. The range of possible
outcomes is still large, and includes the possibility of a major
hurricane landfall in the Carolinas.
A hurricane watch for a portion of the U.S. coast could be
required as early as Thursday evening.