After spending ten days in meteorological limbo-land frustrating forecasters as an “Invest”, 99L finally developed into Tropical Depression Nine, confirmed a NOAA hurricane hunter aircraft late Sunday afternoon. But the storm isn’t done perplexing us yet—the model predictions for the future intensity of the storm remain wildly divergent, even if we now have growing confidence that this storm will track into the coast of Florida north of Tampa on Thursday.Here's the Cone of Uncertainty for 9:
Satellite images on Sunday evening showed a steady increase in the intensity and areal coverage of TD 9’s heavy thunderstorms, though Key West radar showed only a few spiral bands trying to form near the center. The depression is not likely to organize quickly, as it was dealing with wind shear that was a moderately high 15 - 20 knots. TD 9 was also struggling with dry air, as seen on water vapor satellite imagery. Sea surface temperatures (SSTs) remained favorable for development, though, near 30 - 30.5°C (86 - 87°F)....
... Intensity forecast for TD 9
The SHIPS model on Sunday afternoon predicted moderately favorable conditions for intensification, with wind shear falling to a moderate 10 - 15 knots, Monday through Wednesday. SSTs will be a very warm 30°C (86°F), and mid-level relative humidity was predicted to be a reasonably moist 65 - 70%. However, the usually reliable European and GFS models showed little to no development of TD 9 in their latest 12Z Sunday (8 am EDT) runs. Our best intensity model, the HWRF model, had TD 9 rapidly intensifying into a strong Category 2 hurricane just before landfall. Other intensity models like the DSHIPS and LGEM models had TD 9 as a borderline Category 1 hurricane at landfall. This storm’s history has been to under-perform....MORE
Monday, August 29, 2016
Hurricane Watch: "Invest 99L Finally Develops Into Tropical Depression 9 in the Florida Straits"