Nate: Not

Unfortunately, Nate never got far enough to north to be picked up by the wind currents that might have taken it up toward Texas. Now, a newly developing high pressure center will cut Nate off from any chance of easing the drought in Texas.

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A Ray of Hope for Texas

The clump of clouds in the southern Gulf is now Tropical Storm Nate. My earlier posting (see below) discussed that potential path of Nate as being toward Louisiana and that may still be the case. However, some of the models and the National Hurricane Center are taking Nate on a more northerly course. That might — might — bring some moisture in south and east Texas.

However, the storm currently is under very weak steering currents, so this is only educated speculation at this point. Little movement is forecast for Nate for the next day or two.

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A Very Troubling Computer Model

If I had to choose a single computer model to use when analyze and forecast tropical storms and hurricanes, it would be the European Consortium for Medium Range Forecasting Model (ECMWF). It is showing the system now in the Bay of Campeche moving north and strongly intensifying.

This is the forecast for Monday evening showing either a hurricane or tropical storm south of Louisiana.

But, on Thursday, the storm is forecast to have weakened, but has hardly moved.

Another hazard: Tropical storm or hurricane indicated by arrow. It is what is now
tropical storm #14 (see satellite graphic above).

It is too soon to worry about wind speeds or wind location. It is not too soon to be concerned about more heavy rain in the region, given the 15+” that fell with T.S. Lee.

It would be wonderful if the storm were to take a more western path and move into Texas. That is not out of the question.

But, any path farther east than Texas will result in major problems.

Tropical Outlook

Here is the 7pm CDT updated outlook from the National Hurricane Center.

Please let me run down the four weather systems for you:

  • Katia. Not worried about it affecting the U.S. except for rip currents along the East Coast.
  • System #1 in the southern Gulf. Worth watching.
  • System #2 east of Barbados. Probably not a problem.
  • T.D. #14, I think this will bear watching starting this weekend. 
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Tornado Risk Today…

…in the Southeast due to the remains of T.S. Lee.

There is a tornado watch currently in effect:

click to enlarge

Note that the probability of tornadoes is “high.”

The threat is expected to spread east during the day. A 15% probability of tornadoes is relatively high. In fact, anyone in the brown-yellow-red areas should be aware of the latest bulletins if thunderstorms approach.

Update on Tropical Storm Lee

Below is the AccuWeather radar regional radar. I have circled the center of Lee which is just inland over Vermillion Bay, LA moving slowly northeast. 

Here is the National Hurricane Center’s forecast for Lee’s future movement. S = tropical storm and D = tropical depression.  
Between 25,000 and 30,000 are without power at the present time. 
Here is the 24-hour (note: not storm total) rainfall ending 7am Central time this morning. There are several areas that received more than 10 inches. 
Here is the predicted rainfall from now until 8am Eastern Friday morning.
So, what do you do to prepare if you are in an area where heavy rain is predicted?
Most cities’ web sites have flood plain maps for at least the 100-year flood plain. For example, a flood map for Philadelphia is here. If you live in or near a flood plain, please fill your car’s tank with gas, and think about what you would need if you have to evacuate. 

Tornado Threat With Lee

Tornado watch until 10am and I expect this to be extended. As meteorologist Chris Saindon pointed out, there is plenty of wind momentum aloft to cause damaging winds near the ground in addition to the small-size tornadoes likely in this situation. Thanks, Chris!

Update on Lee’s Flooding Threat

Here is the current AccuWeather composite radar at 7:45am CDT. I have added arrows to show the direction of movement of the rainfall. In this case, heavy rain keeps falling over the same areas, adding up to some tremendous amounts.

The flooding threat seems to be increasing from Tropical Storm Lee. Here is an AccuWeather display of estimated rainfall from the NWS radar in New Orleans:

click to enlarge any graphic

Already rainfall amounts of 4″ or more (red) are common in southeast Louisiana. And, the 4″ amounts (note slightly different color scale) are being experienced near the AL-FL border.

While Lee is expected to have sustained winds of 65 mph (with gusts to 75 mph) at landfall which will cause trees to be uprooted with power failures; extensive, widespread flooding will be the worse problem. Why? Because even though 2-6″ have already fallen, storm total rainfall forecasts have been revised upward. 

An additional 19″ of rain is forecast for New Orleans with ≥15″ for Mobile, Gulfport and Hattiesburg! People living in these areas should be prepared for major flooding and evacuations.

And, the threat doesn’t stop in the South.

The bright yellow is 7″ which includes Birmingham and Asheville. That’s plenty of rain to cause at least some flooding. But, as Lee merges with a cold front, the heavy rains continue into the Northeast with about 7″ forecast around Harrisburg.

Here is a map of rainfalls for the last two weeks that includes the rains from Irene:

Where the heavy rains from Lee overlap the areas with saturated soils from Irene, major flooding may redevelop. 

Update on Katia and Lee

I’ve looked over some late data as well as the 10pm National Hurricane Center discussions and no change is necessary to my discussion about Lee below in terms of strength or movement.

However, the bullseye of heaviest rainfall has been moved slightly farther east by one of the new computer models. The bright yellow area is a forecast of  20 to 24″ of rain.

Regardless of the exact position of the heaviest rain, people along the I-10 corridor from New Orleans to the Florida border should be prepared for excessive rainfall and major flooding. This may include washing out major highways and rail traffic.

With regard to Katia, enjoy the weekend. I still believe it is unlikely she will strike the U.S., but even if she does, there will be sufficient time to take precautions after the holiday weekend is over.

Tropical Storm Lee and the Threat of Major Flooding

Lee continues to move very slowly north then turn north northeast.

Winds are expected to be around 65 mph with a few higher gusts when the storm makes landfall.

However, the more serious threat is not the wind, it is the rain.  A few spots in far southeast Louisiana have already recorded more than 4″ of rain.

Radar estimate of rainfall amounts. Darker yellow ≥4″, note small
spot over the Mississippi Delta

On top of what has already fallen, more than 20″ additional is forecast to fall.

NWS rainfall forecast

Major flooding will likely occur and it is quite possible numerous roadways will be washed out in southeast Louisiana and southern Mississippi. There is also a threat of major flooding in west central and northern Alabama where above normal rain has fallen the last 30 days.

If you look at the above map, the melding of Lee along with a cold front could bring heavy rain into New England the first of next work week. The NWS rainfall forecast shows moderate amounts. However, the ECMWF model, from AccuWeather, shows some locations getting more than five inches (dark maroon color) in the Northeast and Middle Atlantic States. Given that some of these areas received heavy rain from Irene, it may cause rivers to rise again.

ECMWF model via AccuWeather’s PRO web site.

It is too soon to pin down how much threat there is to the Middle Atlantic and New England regions but I would advise residents of these areas to continue to monitor the weather forecasts.

I believe this is another major disaster in the making — one of the seemingly endless weather disasters of 2011.

Tropical Trouble!

Rain has already started on the Gulf coast as Tropical Storm Thirteen creeps north at 2 mph. Given the long duration, storm totals may exceed 20″ in spots. Winds could be 50+ mph as the storm intensifies slightly over the weekend.

The flood risk with this system is very high. As I was doing last week at this time, I urge people living in these areas — even if you are in an area that does not traditionally flood — to be prepared in case an evacuation is necessary.

And, tropical storm Katia continues in the Atlantic. There is nothing to worry about for the next five days. However, starting Tuesday, the U.S. east coast will need to begin to pay attention. I still doubt that Katia will get to the U.S. coast but she will be close enough that — after you’ve enjoyed the weekend — you’ll ant to monitor the storm.

Tropical Depression Forming

An Air Force hurricane hunter is going to investigate the system west east of Cancun. It will likely be named a tropical depression later today. It is currently moving west northwest.

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