Tropical Weather Discussion...Tropical Depression 3 continues to slowly become more organized, and has become Tropical Storm Bonnie as of 5p.m. Hurricane hunters have found winds strong enough to classify the system as a tropical storm. The storm continues to spin near the Bahamas, and will approach the Florida Keys Friday. Only a slow strengthening is expected.
Tropical Storm Bonnie Advisory
...Season's third tropical system remains becomes season's second Tropical Storm...Tropical Storm Bonnie...
4p.m. CDT Thursday, July 22, 2010
Latitude: 22.9 N
Longitude: 75.4 W
This position is 200 miles SE of Nassau, Bahamas and 415 miles ESE of Key West, Florida. This is also 1,240 miles SE of Lake Charles.
Maximum sustained winds: 40 mph w/ higher gusts. Bonnie is still in its infancy state, and is still showing signs of strengthening, despite wind shear to the NW of the storm. Slow strengthening is expected as the environment over the storm remains marginally favorable for further development. This storm is still poorly organized, and further re-location of the low-level center is possible as it becomes more organized.
Movement: NW or 310 degrees @ 14 mph. A turn to the WNW and an increase in forward speed is expected on Friday. On this track, TD 3 will move through the Florida Keys and Florida Straits Friday, and into the SE Gulf of Mexico late Friday. An eventual WNW track will bring the system in the general direction of the Louisiana coast late Sunday into Monday.
Pressure: 29.71" or 1006 mb.
Watches/Warnings...There are no changes to the watches and warnings that were issued with the inception of TD 3 this morning. The government of the Bahamas continues the Tropical Storm Warning for the Central and Northwestern Bahamas. A Tropical Storm Warning also remains in effect for the East Coast of Florida from Golden Beach southward including all of the Florida Keys and Florida Bay, and for the West Coast of Florida to Bonita Beach.
A Tropical Storm Watch remains in place to the North of the Tropical Storm Warning area on the East Coast of Florida from Golden Beach to Jupiter Inlet including Lake Okeechobee.
A Tropical Storm Warning means that Tropical Storm conditions are expected within the warning area generally in about 36 hours. A Tropical Storm Watch means that Tropical Storm conditions are possible within the watch area generally within 48 hours.
Rainfall...Rainfall totals of 2-4" are expected to occur over South Florida, with higher amounts of 4-6" possible in some locations. Rainfall totals of 3-5" are expected over the Bahamas, with higher totals up to near 7" expected in isolated locales.
Winds...Winds near Tropical Storm force will spread over the Central and Northwestern Bahamas tonight and Friday, and into South Florida on Friday.Conditions will deteriorate over South Florida beginning late tonight.
Storm Surge...Storm surge levels will rise 1-2' above ground level over South Florida, the Florida Keys and the Bahamas.
Discussion #2...There is no change in strength with this advisory. TD 3 continues to battle shear on its W and NW flank. This is as a result of a Westward moving upper level low over the Eastern Gulf. The ULL is showing signs and accelerating, and becoming further removed from the flow around TD 3. If this occurs, then an environment that will be more conducive for development will take over. It is still uncertain if this will occur. There is much uncertainty in the intensity forecast for TD 3. Nearly all of the forecast models suggest that this system will never reach hurricane status. Some of the models indicate that the shear will remain strong, and eventually kill the system over the Eastern Gulf, and it would only reach the coast as an open wave. The majority of the models, however, keep this system as a tropical storm through landfall. Given the shear out ahead of the system, and the steady forward motion, there is no reason to believe that this system will be more than a tropical storm.
I caution you that while the current projections call for Bonnie to remain a tropical storm until landfall, there is the possibility that degeneration could occur if the shear strengthens, or it could feasibly reach minimal hurricane status- category 1 before landfall. As for landfall, everything still suggests that landfall will occur somewhere on the Louisiana coast Sunday evening or as late as Monday morning. Some of the latest models suggest a reduction in forward speed as the storm pulls into the Central Gulf Saturday. Bonnie will be steered around the periphery of the Bermuda High to its North, and by the current created by the ULL out ahead of the system. Tropical systems always follow the path of least resistance, and can often follow the flow carved up by a previous synoptic scale feature. This appears to be the case with Bonnie. On the current path, the window of opportunity for possible landfall will be between 4p.m. Sunday and 4a.m. Monday. The current official track has been shifted to the right (East) of the first official track this morning. This would make landfall around Vermilion Bay Sunday afternoon. The storm is still in its early stages, and shifts in the forecast track are quite common early on as the center re-locates and models adjust. The official forecast track is essentially a reflection of this, and the models remain clustered over Louisiana. I still believe everyone from the Upper Texas Coast, say near GLS (Galveston) to MOB (Mobile, Alabama) should remain on their toes and closely monitor the future developments of Bonnie.
Tropical Storm Watches will likely be issued for a portion of the Gulf Coast Friday. This should include SW Louisiana. Warnings will be hoisted most likely on Saturday. Conditions should go downhill from E to W across the Bayou State beginning late Saturday, and more significantly on Sunday. Rain chances and wind speeds will increase as Bonnie approaches the coast. Tropical storm conditions should be experienced along the coast by Sunday afternoon continuing through Monday morning. Winds will increase across the entire forecast area, but will decrease incremently the further N and W you go. The main impacts across Louisiana will be in the form of heavy rainfall from the tropical rain bands on Sunday and Monday. The outer rain bands may begin affecting portions of the forecast area on Saturday with moisture lingering over the area through Tuesday. Winds in the 50-60 mph range will be likely along the coast, and 40-50 mph seems likely across the I-10 corridor from Lake Charles to Lafayette. Of course, the worst of the weather will occur to the right (East) of the center of circulation. Where exactly the worst of the weather will occur at this point remains to be seen. It all hinges on the actual track of the storm. It is not so important to just focus on the black line which depicts the center of the storm. Most of the adverse weather conditions will be to the East of the center in this situation. The coastal parishes will stand to see minor storm surge flooding likely on the order of 3-4' to the right of the center. A tornado threat will also materialize to the right of the center as the system moves onshore, and begins to spin down on Monday. Heavy rainfall of 5-10" will also be expected across the forecast area. The most uncertain part of this whole storm will be, what happens to the oil. Unfortunately, Bonnie will track over or very near the Deepwater Horizon Oil Spill site, and through much of the associated slick over the Gulf waters. The strong winds and seas associated with Bonnie will likely drive additional oil towards the coast. It remains to be seen how much oil will move inland, and exactly which areas will be affected. The steering currents will allow this storm to keep moving once it moves inland, but a turn more toward the North is expected near the end of the forecast period as the system rounds the base of the Bermuda high. Everything should be out of our hair as we get into Tuesday with a return to a more normal summer pattern at that time.
The graphical representation will not show that this system is a Tropical Storm, but a special update was sent during this writing to indicate that it was. A full advisory was not issued at that time.
That's all for now. I will have the next complete update just after 10p.m. tonight. The complete forecast discussion with specific information about what type of weather we can expect from Bonnie here across SW Louisiana will follow shortly thereafter.
Have a good evening & God bless!
-DM-
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