By Paul Homewood
The latest NHC bulletin still shows Irma tracking up the west coast of Florida, though they are still no sure where landfall could occur.
As I reported yesterday, the storm degraded somewhat over Cuba, and despite strengthening over water since, wind speeds are at 130 mph. NHC expect that strength to be maintained for another 12 hours before weakening.
This is the full discussion from NHC:
Hurricane Irma Discussion Number 45 NWS National Hurricane Center Miami FL AL112017 500 AM EDT Sun Sep 10 2017
An Air Force Reserve Hurricane Hunter aircraft reported 700-mb flight-level winds of 128 kt in the northeastern eyewall, along with surface wind estimates of 110-115 kt from the Stepped Frequency Microwave Radiometer. In addition, the aircraft data shows that the central pressure has fallen to 928 mb. Based on these data, the initial intensity has been increased to 115 kt, again making Irma a Category 4 hurricane. I
rma has made its long-awaited turn, with the initial motion now 325/7. For the next 36-48 h, the cyclone will be steered generally north-northwestward with an increase in forward speed between a low- to mid-level ridge over the western Atlantic and a developing mid- to upper-level low over the Gulf Coast states and the northern Gulf of Mexico. After that, the system should turn northwestward and then move somewhat erratically near the end of its life as it merges with the low. The tightly-clustered track guidance has changed little since the last advisory, and the new NHC forecast is very close to the previous one. The eye should move across the Lower Florida Keys in the next few hours. After that, the hurricane’s track almost parallel to the west coast of Florida makes it very difficult to pinpoint exactly where Irma will cross the Florida Gulf coast.
Given current trends, some additional strengthening could occur during the next several hours. However, vertical wind shear is increasing over Irma, and the shear is expected to become strong within 24 h. This, combined with land interaction, should cause at least a steady weakening from 12-36 h. The new intensity forecast is slightly lower than that of the previous advisory at those times, but it still calls for Irma to be a major hurricane at its closest approach to the Tampa Bay area. A faster weakening is likely after Irma moves across the Florida Panhandle and starts to merge with the aforementioned upper-level low, and the new forecast follows the trend of the previous one in calling for the system to decay to a remnant low by 72 h and to dissipate completely by 120 h.
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September 10, 2017 at 05:36AM
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