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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Check out this loop. Doesn't it appear that the low level flow around the large convective mass W of Fort Myers and Tampa seems to have slowed down as if a main center is trying to form in that area? Maybe its just the differing speed of the images coming across. The center is still incredibly elongated, but I think it's slowly becoming more focused there as the latest 850mb vorticity charts from CIMSS depict.
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Quoting BayouBorn1965:
Thank you, Levi!


Awesome pic. I really miss the ocean.
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MSLP and Surface Winds from the SPC Mesoscale Analysis page...approximately one hour ago...

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Quoting Hurricanes101:
Levi do you think all that rain south of the Tampa/St Pete area is going to come to the Tampa/ST Pete area?


If that eastern center south of Apalachicola continues to lift straight north then ya they could get some of the convection sneaking into the Tampa area, but if the center starts to rotate into the other one closer to the river then it may pull all the thunderstorms away from the west Florida coast and keep people mostly dry. Right now it looks like the eastern center may try to pull back towards the NW in a Fuji-wara type fashion, so Tampa may not get a whole lot of rain, but some is possible.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
Quoting Hurricanes101:
Levi do you think all that rain south of the Tampa/St Pete area is going to come to the Tampa/ST Pete area?


The outer edge is heading our way right now.
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HAHA I just received some mail from a charecter named FLHL2 or something like that...I think he was upset about some mention of 93 and 94 back when they were invest...so I did what any decent person would do...delete

Really, way too much drama. I may just read Storm's blog, then Doc's, and really use that - button.
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Thank you, Levi!
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Looks to me area east of lesser Antilles has the potential to get the first cv designation as it tries to slip under the ull that's killing 93L. Nice flare-up but could be because it is bumping into the southern edge of same ULL. Heads up northern windward's and Puerto Rico.
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Quoting ElConando:



To a point yes but I wouldn't expect too much improvement tomorrow either. It may get to minimal TS status but we'll just have to see.
Well yeah I'm not expecting too much development either, just saying if it will completely vanish like last night.
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Levi do you think all that rain south of the Tampa/St Pete area is going to come to the Tampa/ST Pete area?
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Quoting NASA101:


Not counter-arguing with Levi here but that wave is around 10 Deg East if not further east and has a LONG way to go before it even it enter the waters of the African coast - if this verifies in 2 weeks time then YES it will be some forecast by the models!! :)


I know. That's why I say they could easily drop it but the pattern is one where we should watch underneath the ridge regardless of what the models say anyway. The only reason I traced what the models were showing back to this wave was out of curiosity so I could track it. This looks like the one they are developing and honestly the stuff we're seeing out of the 2-week ensemble means is incredible.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
There is no center reformation... chance of reformation WSW of tampa is near 0%
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Quoting scott39:
Levi, Do you think TD5 is moving 12mph?


12-hour average motion which the NHC uses yes 12 sounds fine. It might be a tad slower in the short-term motion.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
I've been reading the blog all morning, and like many of you, I'm still trying to reconcile in my own mind what is going on. The primary COC appears to be SW of Panama City. There also is an increasing area of thunderstorm activity SW of Tampa. I suspect that the ULL that passed to the north of TD5 last night grab a piece of energy from TD5 while leaving some mid-level circulation from the original TD5. It is that original circulation that appears to be reforming or as some of you are indicating, relocating. Either way, the environment does not look all that favorable for any dramatic strengthening.
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Thought some may be interested in Phil Klotzbach and his expectation of how the rest of the season should evolve. Link
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Quoting Levi32:


That would be the one yes.


Not counter-arguing with Levi here but that wave is around 10 Deg East if not further east and has a LONG way to go before it even it enter the waters of the African coast - if this verifies in 2 weeks time then YES it will be some forecast by the models!! :)
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Quoting extreme236:
StormW/Drak/Levi have all explained numerous times why this season will be well-above average, but if people don't want to listen I guess that's fine.


The conditions might be coming together but it does not mean that a well-above average season "in reality" will occur.
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Quoting Samantha550:
If the center relocates, what are the implications for track and intensity?

Thanks!


Track will be quite a bit farther east, it will be over water longer, will slow down while farther out in deeper water. That said, it will likely not be a good thing since shear as well will be lessening.
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Quoting gordydunnot:
How did Doc. define a subtropical storm, wide area of circulation with the highest winds located away from center.That if it continues to strengthen to hurricane force it would have to tighten up to the point were it would no longer be subtropical, but fully tropical at that point. I think the nhc went with depression on this storm because they wanted to issue updates that drew attention. When they couldn't find ts winds.IMO


It's not subtropical.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
if the LLC is indeed, reforming..and I believe it is....look for the following.

Poor steering currents and lack of initiative for any progress of our little aggravator in the gulf...will mean more time. time for what?

cat 3 in da gulf within 36 hours..imho
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Levi, Do you think TD5 is moving 12mph?
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Quoting tkeith:
Shen warned ya :)

Yeah, I shoulda listened ;)
Member Since: June 27, 2010 Posts: 0 Comments: 760
Quoting troy1993:
So Levi32 when do you feel we might see our first Cape-Verde type hurricane?


Perhaps as soon as 8-10 days from now. The pattern will be conducive for it and there are strong hints coming out of the models right now.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
Quoting Kristina40:
As it turns out my award for "most ignorant post of the day" may have been premature...
Shen warned ya :)
Member Since: November 1, 2004 Posts: 25 Comments: 8924
Quoting Levi32:


It looks double-barreled right now with two strongest spins, one south of Apalachicola and the other SE of the Mississippi River. If it doesn't wrap in the other center to the east the whole thing may end up east of the NHC forecast track, but we'll have to see. There wasn't as much reformation involved as there was just inability of the system to tighten up and feedback, and as a result it lost control and fractured into a broad circulation with multiple centers. It could still try to wrap up some more before landfall though.
Thanks
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347. unf97
Quoting weathermanwannabe:
The jury will be out on TD5 for about 24 hours me thinks until something more definative happens either way. A barely moving disturbance in the Gulf at this time of the year is very frustrating, and, very difficult to forecast.


You ain't kidding. It is also worrisome because as long as it is barely moving over that warm water in the GOM, and the longer it takes for it to make landfall, the intensity forecast will be a big headache with this.
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Quoting TropicalAnalystwx13:
I think this is rhe wave Levi was talking about in the last part of his blog entry:



That would be the one yes.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
Quoting BahaHurican:
Whoa... what's going on at 20W and ITCZ? It's got the best formation chances in the basin...


Yeah, just checked - there is absolutely nothing right now just south of Cape Verde that warrants such a enhanced probability of tropical formation - I never had much faith in these diagrams!!!!
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As it turns out my award for "most ignorant post of the day" may have been premature...
Member Since: June 27, 2010 Posts: 0 Comments: 760
Quoting SouthDadeFish:
Oh. Well that makes sense now. I guess it will depend on how bad it becomes today to see how strong TD 5 will get tomorrow.



To a point yes but I wouldn't expect too much improvement tomorrow either. It may get to minimal TS status but we'll just have to see.
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Quoting scott39:
Thanks for video. Whats your thoughts on coc relocation?


It looks double-barreled right now with two strongest spins, one south of Apalachicola and the other SE of the Mississippi River. If it doesn't wrap in the other center to the east the whole thing may end up east of the NHC forecast track, but we'll have to see. There wasn't as much reformation involved as there was just inability of the system to tighten up and feedback, and as a result it lost control and fractured into a broad circulation with multiple centers. It could still try to wrap up some more before landfall though.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
How did Doc. define a subtropical storm, wide area of circulation with the highest winds located away from center.That if it continues to strengthen to hurricane force it would have to tighten up to the point were it would no longer be subtropical, but fully tropical at that point. I think the nhc went with depression on this storm because they wanted to issue updates that drew attention. When they couldn't find ts winds.IMO
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I am sorry --- but I am beginning to think the the NWS and folks at NOAA are really jumping the gun on these storms --- only 3 named storms this year --- how ever will they be able to sell global warming...even the weather Channel looks like its bought and paid for by the Government.
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Quoting scottsvb:
There is no center reformation that you guys think you see. The elongated center extends from 29N 88W to 29N and 84.5W with the eastern extent the most convergence point. Chance of this making it to a TS is under 10% as it will come ashore NW Florida over the next 12hrs or so
So the whole ball of mess is moving 12mph?
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278. Floodman 11:55 AM CDT on August 11, 2010

Whistling past the Graveyard

Hey Flood, tell that dude to put PanhandleChuck back where he found him!
Member Since: November 1, 2004 Posts: 25 Comments: 8924
I think this is rhe wave Levi was talking about in the last part of his blog entry:

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The jury will be out on TD5 for about 24 hours me thinks until something more definative happens either way. A barely moving disturbance in the Gulf at this time of the year is very frustrating, and, very difficult to forecast.
Member Since: August 8, 2006 Posts: 0 Comments: 9024
There is no center reformation that you guys think you see. The elongated center extends from 29N 88W to 29N and 84.5W with the eastern extent the most convergence point. Chance of this making it to a TS is under 10% as it will come ashore NW Florida over the next 12hrs or so
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Quoting Levi32:


The upper-level environment will likely deteriorate today before beginning to slowly improve tonight and tomorrow.
Oh. Well that makes sense now. I guess it will depend on how bad it becomes today to see how strong TD 5 will get tomorrow.
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So Levi32 when do you feel we might see our first Cape-Verde type hurricane?
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Link

Interesting radar. Too bad I fail at posting them. LOL.
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Quoting Levi32:


The upper-level environment will likely deteriorate today before beginning to slowly improve tonight and tomorrow.
Thanks for video. Whats your thoughts on coc relocation?
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320. Usually is good but there is an awful lot brightness in the loop atm or is it like that during the early afternoon?
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Quoting jasoncoolman2010xx:
look at this map
Whoa... what's going on at 20W and ITCZ? It's got the best formation chances in the basin...
Member Since: October 25, 2005 Posts: 19 Comments: 21883
Great blog Levi! I do think, especially if this relocates that it will wrap up before landfall.
Member Since: July 1, 2008 Posts: 13 Comments: 7361

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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.