Hurricane Dorian could be a category 4 storm, forecasters say

The map reflects the 11 a.m. hurricane update from the National Weather Service.

Some forecasters now have Hurricane Dorian reaching a category 4 status, according to media reports.

The small eye of Dorian has appeared intermittently in infrared satellite imagery this morning.  Recent reports from a NOAA P-3 aircraft indicate that there is now a double eyewall structure, with a small inner eye only 5 n mi in diameter and a larger 25-n mi diameter outer eyewall. The minimum pressure has fallen to around 986 mb.  The concentric eyewall structure is likely why the aircraft has not found any stronger winds yet in the storm, despite the decrease in central pressure. The initial intensity remains 75 kt for this advisory. 

Aircraft and satellite fixes show that Dorian is moving northwestward, or 325 degrees at 11 kt.  Dorian is forecast to continue moving northwestward during the next 24-36 hours between an upper-level low that will be dropping southwestward across the Florida Straits and a mid-level ridge to the northeast of the hurricane. 

After that time, a ridge is forecast to build to the north of Dorian, which should cause the track to bend back toward the west-northwest. The track guidance becomes more divergent beyond 72 hours, primarily due to model differences in the strength of the ridge and whether a weakness develops in the ridge late in the period.

The new NHC track forecast is virtually unchanged from the previous advisory, and lies very close to the multi-model consensus. It should be noted that the ECMWF, UKMET, and HFIP corrected consensus models remain south of the official forecast.

The spread of the deterministic models and the various ensemble guidance is still considerable at days 4 and 5, and it is too soon to specify where along the Florida east coast the greatest impacts could occur.  Environmental conditions consisting of warm waters and low vertical wind shear along the path of the hurricane should allow for at least steady intensification during the next 2 to 3 days.  With the small inner core and favorable conditions, rapid strengthening also remains a possibility, although not likely in the very short term given the concentric eyewall structure.  The updated NHC intensity forecast calls for Dorian to become a major hurricane on Friday, and shows aslightly higher peak intensity than the previous forecast. The official forecast is at the upper end of the guidance, in best agreement with the HCCA and HWRF models.