Bonnie barely alive

Tropical Depression Bonnie is barely clinging to life. Wind shear of 25 knots and dry air from an upper-level low pressure system over the Gulf of Mexico are taking their toll on Bonnie, which is now just a swirl of low clouds accompanied by a small clump of heavy thunderstorms on the north side of the center of circulation. These thunderstorms are now visible on New Orleans long range radar, and will arrive in coastal Louisiana early this afternoon, well ahead of the center. The Hurricane Hunters are in Bonnie, and have found a much weaker storm with top winds of just 30 mph.


Figure 1. Morning satellite image of Tropical Depression Bonnie. At the time, Bonnie had sustained winds of 30 mph.

Forecast for Bonnie
The current NHC forecast for Bonnie looks good, with the storm making landfall in Louisiana near 9pm CDT Saturday night. According to the latest tide information, this will be near the time of low tide. This will result in much less oil entering the Louisiana marshlands than occurred during Hurricane Alex in June. That storm brought a storm surge of 2 - 4 feet and sustained winds of 20 - 30 mph that lasted for several days, including several high tide cycles. Bonnie will be lucky to be a tropical depression at landfall, and should only create a storm surge of 1 - 2 feet that will come at low tide. This will result in a storm tide level that will inundate land to at most one foot above ground level.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Elsewhere in the tropics
There are no other threat areas of concern today. The only model calling for possible tropical development in the next week is the NOGAPS model, which predicts a strong tropical disturbance could form off the coast of Nicaragua in the Southwest Caribbean about a week from now.

Next update
The next updates will be by wunderground meteorologists Rob Carver and Shaun Tanner. I'm taking advantage of a break in the tropical action to take a few days away. I'll be back blogging on Friday, at the latest.

Jeff Masters