by Glenn "Hurricane" Schwartz
As Fiona goes through the Caribbean Friday, it was still rather disorganized. A couple of things were preventing significant intensification:
1) Big blob of convection (darkest colors) was not under the center of circulation due to too much wind shear. The shear map clearly showed a lot of it near and ahead of Fiona:
Those red lines show areas of highest shear. And the legend at the bottom says red is "unfavorable".
2) Too much dry air around the storm. You can see it as the "bluish" colors north and west of Fiona. As it tries to intensify it will pull some of that dry air into the storm-another factor "unfavorable" for significant development.
This is why the great majority of computer models continue to suggest little if any intensification over the weekend and even next Monday (after 72 hours, things change).
And what about the track? There seems to be more and more agreement that the threat of a direct Florida hit continues to drop. The U.S. East Coast also seems like a minimal threat, too. The many computer models are showing a curve northward if Fiona maintains strength or intensifies. Only the weaker solutions track Fiona more to the west.
Are those tracks consistent with history? They sure are. Look at the historical "analogs", showing similar locations at this time of year. Looks a lot like the current forecasts, doesn't it?
So, at least into early next week, the threats are to the Leeward Islands, Puerto Rico, Hispaniola, and the Southeast Bahamas. Torrential rains, flooding, and even mudslides are possible, especially in areas with mountains. Patterns could change later next week.
Glenn "Hurricane" Schwartz firstname.lastname@example.org