Update - Monday, September 5th, 2011, 11:35AM EDT
At 05/09Z, the NWS Hydrometeorological Prediction Center relocated Ex-TD Lee at 30.2N 90.8W - still in Louisiana, and at 05/12Z, NHC used 30.4N 90.2W for an additional model run on Lee. At 05/15Z, the remnants of Lee were located at 30.5N 89.9W with movement over the past 12 hours generally to the east. The extratropical system is about to enter southern Mississippi and move into Alabama tonight.

Hurricane Katia has completed an eyewall replacement cycle - a bit unusual but not unheard of for a Cat II Hurricane - and movement over the past 6 hours has been more to the WNW rather than NW although the 12-hour average is still NW. NHC expects a general NW motion to continue with an eventual turn to the north and northeast. The track has again adjusted slightly to the east, and although Bermuda, North Carolina, Massachusetts, Nova Scotia and Newfoundland are not in the cone, the overall area of tropical storm force winds has been expanded so some gusty winds will be likely in Bermuda and possible elsewhere along the coast as Katia passes by well offshore during the week.

The tropical wave in the far eastern Atlantic has been designated as Invest 95L. At 05/12Z, 95L was located well southwest of the Cape Verde Islands at 9.1N 29.7W with winds of 25 knots and pressure at 1009MB. Movement overnight was to the west at 14 knots. The tropical wave is developing good structure and active convection with additional development likely as the system moves to the west and west northwest over the next few days.
ED

Update - Monday, September 5th, 2011, 12:15AM EDT
Category II Hurricane Katia is located well to the north of the northern Leeward Islands still moving to the northwest at 13mph. Some additional intensification is possible for the next couple of days as Katia continues to move to the northwest, eventually turning to the north and then northeast. Models have adjusted eastward and so has the NHC forecast track. An upper level low near 32N 52W could begin to have more of an influence on the future track of Katia. Bermuda is currently not in the cone, but additional eastward adjustments to the track are possibly so folks in Bermuda still need to closely monitor any changes in Katia's track.

By midweek, Katia will begin to move over cooler SSTs and this should slowly reduce the sustained winds later in the week. With fairly good model consensus, its looking more and more like Hurricane Katia will remain at sea - but continue to monitor Katia for any unexpected changes. High surf and rip currents are anticipated along most of the eastern seaboard, in the Bahamas, and on Bermuda in the week ahead. Check with your local forecast office for details on expected hazardous beach conditions in your area.

NHC has issued its final advisory on Tropical Depression Lee. Winds and convection are both decreasing as Lee transitions to an extratropical cyclone. All Tropical Storm Warnings have been discontinued. Post TD Lee is now moving northeastward in south central Mississippi and will be moving toward northern Alabama over the next couple of days where the system is expected to merge with a shortwave trough. Flooding rains are still expected to move from the central Gulf coast into the Appalachian Mountains.

An active tropical wave near 9N 28W at 05/04Z is the only other noteworthy feature in the basin at this time.
ED

8:30 AM 4 September 2011 Update
Tropical Storm Lee still is still over the coast of south central Louisiana, near Vermillion Bay. Lee is still quite disorganized, with much of the convection gone on the southwest, and northwestern quadrants.

Some strong rain bands are moving through the Florida Panhandle and Alabama today, and will move up through parts of Mississippi, Louisiana, Arkansas, Alabama, Western Georgia and Tennessee over the next few days as lee weakens over land. The tropical storm warning goes from Destin, FL westward to Intracoastal city, LA.

Katia's official forecast has shifted a bit west from yesterday, however most guidance and water vapor analysis still suggests that it most likely will recurve before the United States. The trends will need to be monitored (especially the trends of the UKMet model vs the trends of virtually everything else). But right now there are more factors favoring a recurve.

7:28 AM 3 September 2011 Update
Bands of heavy rain along with tornadoes continue in the Central and Northeastern Gulf coasts, all associated with Tropical Storm Lee. It's still moving northward but still remains rather disorganized, another few days of rain is expected in the area.

Katia's holding as a category 1 hurricane, as it moves northwest, odds have slightly increased that it will recurve before the US.

1:30 PM 2 September 2011 Update
THIRTEEN has been upgraded to Tropical Storm Lee. While Lee is expected to intensify, within still weak steering currents, flooding will likely continue to be the greatest threat.

6:30 AM 2 September 2011 Update
Tropical Depression 13 remains a highly sheared, but active tropical depression.
Right now, the western side of the storm remains fairly dry, while the eastern side is extremely wet. With the shear, if the storm forms it will likely be a larger system without a strong inner core, which would make it highly unlikely to strengthen too much.

It will, however, be enough to bring large amounts of rainfall to the Northern Gulf, and some rainfall to the eastern Gulf. It is possible for the storm to be closer to a hybrid storm than a classic tight core tropical cyclone. Upwelling will also likely prevent too much intensification. The forecast calls for it to be upgraded to a Tropical Storm later today.

Texas it looks like, unfortunately, won't see much from this system.

There is virtually no movement with the storm right now, as the center is relocating more than moving, and the steering currents remain weak, which means days of the system offshore, bringing band after band of rain to Louisiana and surrounds, with heavy rain and the possibility of short lived tornadoes.

Any east facing coastal areas in the Northern Gulf will be prone to some coastal flooding with prolonged easterly winds. Winds will be slow at first, but gradually increasing through the days until the system exits. Rainfall will be very dependent on where the bands go, 5-10" is possible, some places more.

Track wise, pick a place, there is very little skill at forecasting a track of a virtually stationary tropical storm, generally anywhere in the tropical storm Warning area.

Katia remains a tropical storm this morning, and odds still marginally favor it turning out to sea before the United States. The area south of Nova Scotia may have a chance to develop before it gets into areas too cold.

Original Update
Tropical Depression 13 forms in the Gulf of Mexico about 225 miles southwest of the mouth of the Mississippi river.

Tropical Storm warnings are now up for the northern Gulf of Mexico coastline from Pascagoula, Mississippi westward to Sabine Pass, TX.

Tropical Depression 13 is forecast to become Tropical Storm Lee tomorrow. It is expected to move extremely slowly as it approaches the northern Gulf coastline, dumping very heavy rainfall.

TD#!3 is a borderline tropical depression, and is still quite disorganized at the moment and the center may "Reform" a few times before it gets its act together. Those in the Tropical Storm warning area will likely see an extended period of windy conditions with wave after wave of heavy rainfall.

Katia was downgraded to a Tropical Storm being under the influence of shear, it is forecast to regain strength later. Although odds still slightly favor recurve from the US, it is not a healthy margin and needs to be monitored over the next week or so. It appears it will go safely northeast of the Caribbean, however.

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Long term Central Atlantic wide area Water Vapor Satellite for Hurricane Season Peak flhurricane)

Long term West Atlantic wide area Water Vapor Satellite for Hurricane Season Peak flhurricane)