"Dorian" Encounters the Hostile Conditions....
has found itself amongst the very dry mid & upper level air & is beginning to encounter the increasing west & southwest shear. The hostile environment is evident on satellite images. Maps below show the pitfalls ahead for "Dorian" including:
** A huge slug of very dry mid & upper level air is ahead over the Central Atlantic -- see the water vapor image -- 5th image below. The rust color is extremely dry air.
** Wind shear picks up dramatically over the Central Atlantic between Puerto Rico & about 50 degrees W (see last image below). There is then a small area of much lower shear followed by another area of high southwesterly shear environment over the W. Atlantic in association with a persistent upper level trough near the U.S. east coast.
Global forecast models remain less than enthusiastic about this system...& with good reason. At this point, the NHC maintains a tropical storm to north of Puerto Rico by early next week moving into the SE Bahamas by midweek. At least some semblance of an upper level trough still looks to be over the Western Atlantic next week (roughly where there is a trough now - see 4th satellite image below) which would probably continue/reinforce shear & also encourage a northwest or north turn (with the strong Bermuda high fairly far to the east/northeast over the Atlantic) in the long term. The shallow (weak) nature of the system -- if "Dorian" remains weak -- should allow the system to move along quickly...possibly steered more by the low level winds vs. mid/upper level flow....unless there is more strengthening than I currently expect. This implies more west/northwest movement next week as the European model has been indicating placing a weak system -- possibly merely a wave -- near Fl. about midweek. The GFS model has been bouncing back & forth between a stronger system & a weak one &, therefore, has been more inconsistent on a track. When a model run shows a stronger "Dorian", the track is more north with earlier recurvature....when showing a weaker system then a more west movement. The GFS has recently shifted more south with a very weak system moving across the Northern Caribbean.So....at this point...
.I remain on the side of "Dorian" being relatively weak -- or even dissipated -- once it moves or tries to move into the SW Atlantic next week. IF there were to be any effects on the First Coast, it would be the middle &/or end of next week & these effects -- right now
-- would appear to be relatively minor.
Tropical waves moving west off the coast of Africa are showing little organization with few concerns for at least the next week as it appears now.
Forecast models plot below courtesy S. Fl. Water Management District (excellent agreement into early next week)....ultimate forecast will hinge on the trough remaining near the east coast which would tend to cause recurvature -- to at least some degree -- ... & whether or not "Dorian" can survive the generally hostile environment (shear) it will encounter in the long term.