Tropical Depression Five a heavy rain threat; the smoke clears in Moscow

By: Dr. Jeff Masters , 3:23 PM GMT on August 11, 2010

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Tropical Depression Five is currently weak and disorganized, but it has the potential to organize into a potent rain-maker that may bring extremely heavy rains to Louisiana, Mississippi, Alabama, and Georgia over the next four days. Outer rain bands from TD 5 are already affecting the New Orleans region, where as much as two inches of rain has fallen in isolated regions. TD 5 has only limited heavy thunderstorm activity at present, thanks to an infusion of dry air early this morning from an upper-level low pressure system over the Gulf of Mexico. However, TD 5 is steadily recovering from this blow, and water vapor imagery shows the atmosphere is moistening in the eastern Gulf of Mexico as TD 5 builds more heavy thunderstorms. Wind shear is currently a moderate 10 - 15 knots over TD 5, and water temperatures are very warm, 31°C. The Hurricane Hunters have left TD 5, and a new aircraft is scheduled to arrive this afternoon.


Figure 1. Morning radar image of TD Five from the New Orleans radar.

Forecast for TD 5
The latest SHIPS model forecast predicts that wind shear will drop to the low range, 5 - 10 knots, by tonight, and remain low for the remainder of TD 5's life. The main hindrance to development will be the current large, disorganized nature of the storm's circulation. Without a tight, well-defined center of circulation, it will take time for the storm to intensify, and I don't expect TD 5 will have time to become more than a 50 mph tropical storm. NHC is giving TD 5 just a 2% chance of reaching hurricane strength. The main threat from TD 5 will be rainfall. This is a slow-moving storm, and the steering currents pushing the storm towards the coast are expected to weaken Thursday and Friday. TD 5 will likely slow to a crawl on Thursday and Friday, moving at just 3 - 5 mph. This will allow the storm to dump very heavy rains in excess of eight inches in isolated regions.

93L
There is not much new to report on the tropical wave (Invest 93) in the middle Atlantic Ocean that has been close to tropical depression status for three days now. The disturbance has a well-defined surface circulation, but only a limited amount of heavy thunderstorm activity, thanks to dry air aloft and wind shear of 10 - 20 knots. Wind shear is expected to stay in the moderate range, 10 - 20 knots, over the next three days, which is low enough that 93L could become a tropical depression at any time during that period. NHC is giving 93L a 70% chance of developing into a tropical depression by Friday morning. The GFS, GFDL, and HWRF models predict 93L will develop, and the GFDL forecasts that the storm will become a hurricane. A strong trough of low pressure moving across the central Atlantic is recurving 93L to the north, and the system should only be a concern to shipping interests. None of the reliable computer models are forecasting tropical cyclone development in the Atlantic over the next seven days, other than for 93L.

Moscow's air clears, but it is still extraordinarily hot
A thunderstorm blew through Moscow early this morning, bringing a little rain and a very welcome shift of wind direction. The wind shift freed the city from the persistent wild fire smoke that had plagued the city for seven straight days. Temperatures at Moscow's Domodedovo airport hit 35°C (95°F) today, the 29th day in row that temperatures have exceeded 30°C (86°F) in Moscow. The average high temperature for August 11 is 21°C (69°F). Moscow's high temperatures have averaged 15°C (27°F) above average for the first eleven days of August--a truly extraordinary anomaly. There is some modest relief in sight--the latest forecast for Moscow calls for high temperatures of 30 - 31° (86 - 88°F) Thursday through Sunday. This is still 20°F above normal, but will be a welcome change from the extreme heat of the past two weeks. Long range forecasts from the ECMWF and GFS models show no major change to the ridge of high pressure locked in over Russia, for at least the next seven days. However, both models suggest that a trough of low pressure may be able to erode the ridge significantly 8 - 10 days from now, bringing cooler temperatures of 5°C (8°F) above average.

Next update
I'll have an update this afternoon between 3 - 4 pm EDT.

Jeff Masters

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Great blog Levi! I do think, especially if this relocates that it will wrap up before landfall.
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Quoting washingaway:
Low Cloud Product
Great loop. Seems like the circulation is becoming more focused farther SE, right on the NW edge of the convection.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
Quoting SouthDadeFish:
Yes, which is why I'm confused. I thought things were going to become more favorable, but shear looks to at least be temporarily increasing in the area.


The upper-level environment will likely deteriorate today before beginning to slowly improve tonight and tomorrow.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
323. unf97
Quoting angiest:


How far away from Tampa?


If there is a reformation, it would be approximately 100-150 miles off the coast of Tampa.
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Quoting angiest:


How far away from Tampa?


If it did relocate,Approximately 140 miles to the south-west of Tampa.
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Always nice to see the ESL by LSU Imagery here.

Its good stuff.
Member Since: July 3, 2005 Posts: 428 Comments: 129853
Low Cloud Product
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Quoting btwntx08:

a relocation of the coc wsw of tampa


How far away from Tampa?
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Quoting btwntx08:

for anyone else not ike
BTWN... check u wundermail.
Member Since: October 25, 2005 Posts: 19 Comments: 22730
Quoting btwntx08:

a relocation of the coc wsw of tampa
The point I was making with the Football analogy, is that the whole area is just sitting there. And it doesnt look like its moving 12mph. It could very well be relocating.
Member Since: June 13, 2009 Posts: 0 Comments: 6912
Quoting ElConando:


Seems so. I haven't had a good beat on it since yesterday.

Watch it, you are close to crude there!! LOL
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If the center relocates, what are the implications for track and intensity?

Thanks!
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It almost appears that TD 5 wants a "do over"...
Member Since: June 27, 2010 Posts: 0 Comments: 760
Most recent model runs on TD5.
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Member Since: July 3, 2005 Posts: 428 Comments: 129853
I think the center is relocating , you are right bro.
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Interesting how the NAM deals with TD5 vs GFS.

Also interesting is how the NAM picks up on a system out of the Carribean.

Link
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Looks like TD 5 has some tricks under her sleves. If the COC is reforming SE of where it is forcasted I dare to say all bets are off then for a Cat 1 or maybe even Cat 2. That new suspect COC is way south of where they have it currently positioned. Any thoughts?
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Hadnt noticed the new blog as I was typing a message on the old one. Oops.

Short and sweet: I believe, as has been mentioned, that we are seeing a new LLC formation just east of the current low marked.



A close inspection of the vort map shows gradients of the 'current' low with a newly deeper 850mb mark just off the coast of florida. I believe this is directly associated with the ball of convection near the area, and we will see this become the new center over the next few hours.

The moisture train between this area and the ULL is just that, a moisture train, and isnt real evidence of a broad LLC.

Just my opinion.
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Good morning all.

Blog Update:

Tropical Tidbit for Wednesday, August 11th, with Video
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting Keys99:


Wow, looks at those two lows in the SH, really nice looking storms.
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Quoting extreme236:


"ALTHOUGH THE UPPER-LEVEL PATTERN IS FORECAST TO GRADUALLY BECOME
MORE CONDUCIVE FOR STRENGTHENING..."
Yes, which is why I'm confused. I thought things were going to become more favorable, but shear looks to at least be temporarily increasing in the area.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
Back again, TD5's coc now is at 26.4N 85.2W by my best estimate, so a westward motion seems to be in order although it's hard to see the exact surface spin with it tilted east to west. It also has freed itself from the ULL and should begin to take advantage of closing off it's western side. East side is looking pretty good overall and outflow getting better established. Also the water vapor imagery shows new banding breaking free into the NE quadrants. Pretty neat system.
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Quoting extreme236:


Agreed. NHC has got to be annoyed with this thing lol


Seems so. I haven't had a good beat on it since yesterday.
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Quoting btwntx08:

yes also notice very low shear in the carribean
Very true. Looks quite hospitable at the moment.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
Nola Roux Updates TD-5
Member Since: July 3, 2005 Posts: 428 Comments: 129853
Photobucket
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Quoting wayfaringstranger:


Kristina I am still contemplating my next Ironman at PC. Whats it like for an ocean swim in October?


Probably a bit chilly depending on how late in October. The Gulf was super hot this year though so it might stay warmer longer. The weather is usually in the low 80's early on in October so you should be fine.
Member Since: June 27, 2010 Posts: 0 Comments: 760
Quoting extreme236:


Agreed. NHC has got to be annoyed with this thing lol
I know I am, and im not even forecasting. LOL
Member Since: June 13, 2009 Posts: 0 Comments: 6912
Quoting SouthDadeFish:
The ridge is starting to make itself known... Shear starting to increase.


"ALTHOUGH THE UPPER-LEVEL PATTERN IS FORECAST TO GRADUALLY BECOME
MORE CONDUCIVE FOR STRENGTHENING..."
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Quoting DestinJeff:
1500 UTC ... odd things, man.

Vorticity becoming more focused in the convective mass west of Tampa.
Member Since: August 12, 2007 Posts: 11 Comments: 2448
Quoting SQUAWK:


Don't try to teach a pig to sing. It wastes your time and it annoys the pig.
WOW!!! WE have blogging pigs?!?!?! Amazing!!!! Call CNN!!!! No wonder we forecast better than NHC, even....

LOL

[sorry, couldn't resist...
Member Since: October 25, 2005 Posts: 19 Comments: 22730
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288. IKE
12Z CMC...
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Have a nice afternoon everyone. Will be back for the Doc's update at 4.
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Quoting reedzone:


That proves my point on the relocation, notice stronger vorticity where I see the new swirl...


Agreed. NHC has got to be annoyed with this thing lol
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Quoting Kristina40:
I guess I'd better go out and swim my laps before it starts raining. I'm in PC as well Eagle.


Greetings Kristina...You should be fine...most of the rain has remained off-shore...I would expect to see some in an hour or two based on the radar. Take care.

Very Respectfully,

Jon
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Quoting Kristina40:
I guess I'd better go out and swim my laps before it starts raining. I'm in PC as well Eagle.


Kristina I am still contemplating my next Ironman at PC. Whats it like for an ocean swim in October?
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Quoting Patrap:
Roger Dat,..Jon
trailing rains vector LIX next 72 to 96 hrs over
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Quoting btwntx08:

not buying that
what are you buying?
Member Since: June 13, 2009 Posts: 0 Comments: 6912
Quoting DestinJeff:
1500 UTC ... odd things, man.



That proves my point on the relocation, notice stronger vorticity where I see the new swirl...
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263. btwntx08 12:51 PM EDT on August 11, 2010

I was just looking at the updates; they have the "low" marked at due south of Mobile sandwiched between two ULL cells.....I'm wondering if NHC is going to downgrade it later today due to a lack of any organized COC.
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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