Tropical Storm Emily struggled through most of last night and today with disorganization, an aftereffect of its multivortex structure as an unnamed disturbance. However, it has become better stacked today, with convection blowing up over its center. It still has a long way to go, despite its more pleasing appearance in satellite photos.
Steering in the short term is straightforward. Emily has been generally on the left side of the forecast track for most of the day, and it is now expected to make landfall in the Dominican Republic as a tropical storm. Weaker systems generally weather the mountains better than stronger ones, provided that they do not linger in the area; therefore dissipation of the system seems comparatively unlikely.
Models conclude that trough will miss Emily
The models have largely converged on a scenario in which the trough that is to weaken the Bermuda High will be gone before it can force the full recurvature of Emily. The ridge is expected to build back in, and the GFS shows the hurricane being trapped off the coast of Florida, unable to move ashore because of another ridge, stalling until a shortwave trough lifts it away. The GFDL and HWRF models, which take their input from the GFS, both show a very close approach to the east coast of Florida, with the HWRF showing near-hurricane-force winds onshore. The NOGAPS shows this same scenario without the stall. In this scenario, a landfall on the Outer Banks of North Carolina occurs, followed by a pull up the Atlantic seaboard (offshore) and out to sea.
The Canadian model shows a very weak system, probably no more than a mild tropical storm, making landfall on the east coast of Florida and then being merged into the shortwave. I should observe that the Canadian model now shows the first low strengthening to 988 mb at sea and reducing the Bermuda High to its winter stage (the Azores High), which does not seem remotely reasonable to me for an August system. I am not putting a lot of faith in this aspect of the Canadian solution.
The European model also shows a “screwy” solution, amplifying the shortwave trough to 992 mb at sea, while completely dissipating Emily over Hispaniola. Although unlikely in my opinion, dissipation of the tropical storm is certainly possible, as yesterday’s blog entry said, but I am having great difficulty believing that either of the baroclinic low pressure systems involved in this will reach 990 mb levels. The first trough is currently located in New England producing a severe weather risk, and it is analyzed at 1002 mb.
Bottom line, I am giving a highly skeptical eye to anything that destroys the Bermuda High at the beginning of August and amplifies low pressure cores to winter levels, especially when they have not been doing this consistently. Any land-free recurvature of Emily depends entirely on such “bombs,” and the approach to the East Coast will be so close that a weaker trough or shortwave will make all the difference in the world in what wind speeds are felt onshore and whether landfall occurs.
Gulf Coast threat decreases… for now
As should be apparent, the threat to the Gulf Coast states has decreased over the course of the day (with a caveat). The current thinking is that the trough will lift Emily northward enough to miss an entrance into the Gulf of Mexico. However, this could change if the storm stays south and west enough, or the trough is weaker than expected at sea.