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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827. angiest
3:16 PM GMT on August 12, 2010
Quoting robj144:


But that was before satellite, so we don't know how many never hit land.


Exactly. As I recall from reading as well as listening to a well-respected hurricane expert (Dr. Neil Frank), seasons before the advent of satellites are likely to have had multiple missed storms because they formed too far east and never ventured far enough west to be reported. The 1933 season is, I believe, through to have had somewhere between 3 and 5 more storms than officially reported. Additionally, small storms like Marco, even forming in well-traveled waters, may have been missed. I seriously doubt 1914 had a lone tropical cyclone like the official record indicates.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
826. BahaHurican
12:42 AM GMT on August 12, 2010
Conclusions and Observations from Klotzbach's Chart and My Extension Thereof

1. Anybody who expects 12 - 15 named storms this year is well within the climatology. Anybody who expects 19 likely believes there are some climatologically anomolous conditions which would predispose the basin towards much higher than average activity levels, both in term of named storms and in terms of ACE.

2. We can reasonably expect the season to last beyond 1 Nov, regardless of number of named storms and / or ACE. One low ACE season had 15 named storms; another initiated its final storm on 9 Dec.

3. There seems to be no immediately obvious correlation between number of storms and number of major hurricanes. 1950 and 1973 both had 13 named storms; both had their second hurricane form on 20 Aug; both seasons ended in mid-Oct [18th and 16th respectively]. 1950 had eight majors; 1973 had one.

I'm sure there are other things to think about from this data. But it is interesting to note that five of the 7 low or average ACE years took place between 1970 and 1975...
Member Since: October 25, 2005 Posts: 19 Comments: 20742
825. BahaHurican
12:26 AM GMT on August 12, 2010
OK. Here's the second part of my futzing about with Klotzbach's table of La Nina years correlated to date of 2nd hurricane formation. This table references 16 La Nina years from 1950 to 2009 and gives the date of formation of the second hurricane and the seasonal ACE for each year.

I collated some additional data relating to these 16 seasons, then looked for additional trends. I gathered information about the formation date of the FINAL storm in each of these seasons, the total number of named storms, and the total number of major hurricanes.

Final Hurricane Formation Date

The formation date for the final storm of the selected seasons ranged from 4 Oct to 9 Dec, and the mean formation date was 3 November. 9 of the 16, or 56.5%, formed on or after 1 November. [NOTE: while I did not record dissipation dates, many storms forming after 20 Oct continued into November.] 67% of seasons with above-average ACE ended with a storm that formed after 31 Oct; the average date was 4 Nov. Again, 1995 fell into the anomalous category, with its 19th storm forming on 27 Oct.

Total Number of Named Storms

As has been presented in other research, La Nina seasons tend to have above average numbers of named storms. The average of these 16 seasons is 11.81, which can be rounded to 12. The smallest number is 8, seen in the 1956 and 1973 seasons, and of course 1995 has the largest, 19. Interestingly enough, seasons with above average ACE only averaged 0.97 more storms than the sample mean, though they did see 2.21 more storms on average than the 10.57 mean of years that had average and below average ACE. However, even storms with average and below average ACE beat the seasonal average of named storms.

Total Number of Major Storms

For the La Nina years Kotzbach focused on, number of major hurricanes varied from 1 to 8 per season. There was a high correlation between seasonal ACE and number of major storms; average and below average seasons [seven] had a mean of 1.86 cat 3 - 5 hurricanes, while the above 100 ACE seasons averaged 5 major storms. The mean across the set was 3.86 major hurricanes per season. Only one high ACE season, 1954, had fewer than three major hurricanes, and every below 100 ACE season except 1971 and 1973 had at least two major storms.

I'm adding some final conclusions and observations to this stuff in my blog... eventually. I'll post a comment about it when I'm done...
Member Since: October 25, 2005 Posts: 19 Comments: 20742
824. robj144
11:03 PM GMT on August 11, 2010
Quoting BreadandCircuses:
I know 1914 had no hurricanes, I just saw that graphic yesterday, it had 1 lone TS


But that was before satellite, so we don't know how many never hit land.
Member Since: August 19, 2008 Posts: 0 Comments: 825
823. twhcracker
9:02 PM GMT on August 11, 2010
Quoting CaribbeanIslandStorm:

What do you think of this wave close to the islands?


it is very red! and there is a green blob around bermuda that has developed a face like the man in the moon. or is it.... SATAN
Member Since: July 30, 2007 Posts: 6 Comments: 1448
822. twhcracker
8:57 PM GMT on August 11, 2010
Quoting btwntx08:
sry all im having a bad day kristina u accepted my apologize over a month ago somethings it happens plz forgive me


i will forgive you but admit i was thinking gosh, there are a lot bigger fish to fry here than smiley faces :)
Member Since: July 30, 2007 Posts: 6 Comments: 1448
821. twhcracker
8:47 PM GMT on August 11, 2010
Quoting Goldenblack:
fallins...

You are a genius, why doesn't everyone just listen to you! I have no idea why you are here, where all of us know littles are gathered. It must be sooooooo annoying for you to be sooooooo right all the time......just post and post and post and *sigh* no one gets it......lol


he writes in quatrains.
Member Since: July 30, 2007 Posts: 6 Comments: 1448
820. StormGoddess
8:32 PM GMT on August 11, 2010
Hey there everybody! The area around 57W-59W is now extremely suspect. Not one but 2 systems are present there at once. Our yellow circle to the south, and the new addition that 93L has just appeared to have "added".Photobucket
Member Since: June 10, 2010 Posts: 6 Comments: 570
819. rossclick
8:28 PM GMT on August 11, 2010
new blog
Member Since: May 30, 2010 Posts: 0 Comments: 111
818. charlestonscnanny
8:27 PM GMT on August 11, 2010
Levi and Storm W, I agree with ya'll about the east coast being a target this year for a possible hurricane hit. You both have tought me so much in the past 2 years reading and absorbing your knowledge. I live in Summerville/Charleston,SC and remember Hugo slamming into Charleston in 1989. We also had a major snowstorm on Dec. 24 of that year too. Looking forward to learning more and maybe representing my beautiful "lowcountry" on this blog.
Member Since: August 5, 2010 Posts: 0 Comments: 107
817. StormChaser81
8:22 PM GMT on August 11, 2010
Quoting Jeff9641:
Some areas of Port Orange approaching 8". WOW!


Even with Tornado Warning
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816. BahaHurican
8:22 PM GMT on August 11, 2010
I'm still stymied as to why we are seeing so much development of these systems by day in contrast to by night...
Member Since: October 25, 2005 Posts: 19 Comments: 20742
815. tatoprweather
8:21 PM GMT on August 11, 2010
Quoting CaribbeanIslandStorm:

What do you think of this wave close to the islands?


StormW or Levi....I noticed a lot of convection generated today in the system near 55W but at the same time seems that the ULL over Puerto Rico is pulling all that convection way north from the main circulation. Can we expect a strong rain event in the islands or dou you think that the system could develop into something stronger? Appreciate your response.
Member Since: April 29, 2010 Posts: 0 Comments: 136
814. Greyelf
8:18 PM GMT on August 11, 2010
Quoting gbreezegirl:
So much for the update Dr. M. was supposed to give us between 3-4 p.m. I guess there wasn't much to talk about.


See post #804.
Member Since: June 5, 2007 Posts: 18 Comments: 838
813. xcool
8:17 PM GMT on August 11, 2010
new blog
Member Since: September 26, 2009 Posts: 2 Comments: 15603
812. xcool
8:17 PM GMT on August 11, 2010
newwwwwwwwwwwwwwwwwww blog
Member Since: September 26, 2009 Posts: 2 Comments: 15603
811. DoubleAction
8:16 PM GMT on August 11, 2010
I see an elongated funnel like circulation of TD5 forming now west of Tampa, which indicates to me the entire system is slowly getting better organized, it did look like two seperate circulations consolidating to me.
Member Since: August 13, 2008 Posts: 0 Comments: 159
810. gbreezegirl
8:15 PM GMT on August 11, 2010
So much for the update Dr. M. was supposed to give us between 3-4 p.m. I guess there wasn't much to talk about.
Member Since: September 7, 2005 Posts: 0 Comments: 274
808. SLU
8:15 PM GMT on August 11, 2010
Quoting CybrTeddy:
The ECMWF and GFS develop a system off Africa in 92 hours or so.


Well there seems so be some kind of system there but perhaps develop might be too strong a word to use.

The ECMWF takes the system almost due northwards immediately after it gets its toes in the water.
Member Since: July 13, 2006 Posts: 12 Comments: 4734
807. washingaway
8:15 PM GMT on August 11, 2010
Low Cloud Product
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806. Levi32
8:14 PM GMT on August 11, 2010
Quoting AstroHurricane001:
IMO, subtropical hurricanes CAN develop. Hurricane Karl in 1980 developed from the center of a cold-core extratropical storm before turning subtropical.



Sure, the perfect storm was also an example of a "subtropical hurricane" as was Hurricane Vince in 2005.

The debate on it comes from the fact that subtropical cyclones aren't supposed to have wind maxima close to the center, which is a characteristic generally reserved for tropical cyclones. However, if you have such a storm like Karl, Grace, or Vince with wind maxima near the center and the structure of a tropical cyclone, yet it's cold-core aloft, you can't call it fully tropical. There are several different ways you can have a subtropical cyclone which is why even having the term is controversial.
Member Since: November 24, 2005 Posts: 628 Comments: 26460
804. Greyelf
8:14 PM GMT on August 11, 2010
New blog, guys.
Member Since: June 5, 2007 Posts: 18 Comments: 838
801. StormGoddess
8:13 PM GMT on August 11, 2010
Quoting cheetaking:


This visible loop is wild...
NOAA 93L Visible Floater

Wow, that is wild! You can easily see the energy transfer from one area over to the other! :O
Member Since: June 10, 2010 Posts: 6 Comments: 570
800. scott39
8:13 PM GMT on August 11, 2010
Does anybody think TD5 is still TD5?
Member Since: June 13, 2009 Posts: 0 Comments: 6706
799. wayfaringstranger
8:12 PM GMT on August 11, 2010
Just a little quiz here....

What year did we go the longest before having the first hurricane?

What year were there no hurricanes?
Member Since: July 12, 2010 Posts: 0 Comments: 235
798. nwFLstormstalker
8:12 PM GMT on August 11, 2010
Ok, but can someone tell me what the circulation is visible on long range nexrad RADAR out of RED BAY(tallahassee) . this is not a broad circulation....
Member Since: August 24, 2008 Posts: 0 Comments: 51
797. Neapolitan
8:12 PM GMT on August 11, 2010
Better and better...but will it hold? Click the image for full-size. (P.S.--the little island near the lower left is Barbados.)

Member Since: November 8, 2009 Posts: 4 Comments: 13304
796. BFG308
8:12 PM GMT on August 11, 2010
Quoting swlavp:
Post 745...Why all the Anger?


Post 745? I Don't See a Post 745...
Member Since: June 17, 2010 Posts: 2 Comments: 35
795. Prgal
8:11 PM GMT on August 11, 2010
Quoting reedzone:


Interesting, but should move into an environment where it will get squished.. accoridng to Levi.


I saw Levi's video and it was great but according to this page, that blob should pass north of the islands. Link

Member Since: September 7, 2006 Posts: 0 Comments: 918
794. flsky
8:10 PM GMT on August 11, 2010
Tornado warning in SDB right now.
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793. xcool
8:10 PM GMT on August 11, 2010
recon what home
Member Since: September 26, 2009 Posts: 2 Comments: 15603
792. hcubed
8:10 PM GMT on August 11, 2010
Quoting clwstmchasr:


A right hook followed by a left jab then a right ear bite...


...and he still won't post his source about Watts.

If it's his own opinion, fine.

If he's taking info from a site, claiming it as his own and not giving proper credit, well, they have a name for that...

Member Since: May 18, 2007 Posts: 289 Comments: 1639
790. will45
8:09 PM GMT on August 11, 2010
Quoting Tropicaddict:
The HH are in TD5 now, right? What are they finding?


i think they gave up and went home
Member Since: July 18, 2009 Posts: 1 Comments: 994
789. 7544
8:09 PM GMT on August 11, 2010
iz 93ls twin moving west
Member Since: May 6, 2007 Posts: 0 Comments: 6618
788. Greyelf
8:07 PM GMT on August 11, 2010
Quoting btwntx08:
for feeling bad again today i bang myself with my head 5 times


I would suggest against doing that anymore. It's apparent you've done it too much already.
Member Since: June 5, 2007 Posts: 18 Comments: 838
787. RitaEvac
8:07 PM GMT on August 11, 2010
hmmmm.... well gang, so far up to now conditions haven't been favorable since Alex. Everything, invest, depressions just can't get it together. If you would of told me in May we would only have 3 named storms on the 11th of August I would of slept through June and July and the first week of August.
Member Since: July 14, 2008 Posts: 1 Comments: 9625
786. BahaHurican
8:07 PM GMT on August 11, 2010
Quoting AstroHurricane001:


The Central Atlantic Triangle is VERY apparent...and the system near 25N, 50W looks like Bonnie. WHY did the NHC downgrade it to medium-risk on the TWO?!
It fell apart.
Member Since: October 25, 2005 Posts: 19 Comments: 20742
785. Tropicaddict
8:06 PM GMT on August 11, 2010
The HH are in TD5 now, right? What are they finding?
Member Since: September 25, 2007 Posts: 0 Comments: 207
784. CaribbeanIslandStorm
8:06 PM GMT on August 11, 2010
Quoting StormW:


One way to tell (which is why I placed the "L" on the satellite pic) is if you go to the RGB loop, look at the lower cloud deck. Notice how the lower clouds over FL. are moving toward the NW, and then backing and coming down over LA. Then south of the system, you can see how they are coming up from the WSW. You can see where they"meet".

rgb loop


StormW What do you make of this wave near the Antilles ?
783. CybrTeddy
8:05 PM GMT on August 11, 2010
The ECMWF and GFS develop a system off Africa in 92 hours or so.
Member Since: July 8, 2005 Posts: 259 Comments: 23015
782. stormpetrol
8:05 PM GMT on August 11, 2010
93L has split imo to become separate 2 entities both could be TDs or TS imo.
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781. reedzone
8:04 PM GMT on August 11, 2010
Quoting CaribbeanIslandStorm:

What do you think of this wave close to the islands?


Interesting, but should move into an environment where it will get squished.. accoridng to Levi.
Member Since: July 1, 2008 Posts: 13 Comments: 7334
780. TexasGulf
8:03 PM GMT on August 11, 2010
Quoting angiest:


Rita didn't make landfall in Texas, but rather just across the border in LA. ;) And as stated, Ike was not technically a major.


Actually, Rita made landfall at the mouth of the Sabine River, the center of which is the border dividing Texas from Louisiana. Rita made landfall between Sabine Pass, Texas, and Johnson Bayou, Louisiana, at 02:38 CDT on September 24, 2005 as a Category 3 Hurricane with winds at 115 mph. It was directly on the border of the two states. I will agree Louisiana got the worst of it.
Member Since: April 28, 2008 Posts: 0 Comments: 354
779. CaribbeanIslandStorm
8:03 PM GMT on August 11, 2010
Quoting reedzone:
TD5 continues to become better organized, still very broad but the rubber band look is now an oval look, symmetrical.

What do you think of this wave close to the islands?
778. AstroHurricane001
8:03 PM GMT on August 11, 2010
Quoting cheetaking:
This is crazy... I really think this thing split in two. It looks like the old area of convection split off and developed its own surface low, and now the old LLC is firing up intensely. We could end up with two storms out of this one.

This visible loop is wild...
NOAA 93L Visible Floater


Wow, massive convergence over the northeastern component and a circulation setting up after the collapse of the original convection. NE component drifting NE, W component drifting W. We have a co-interacting triangle in the Atlantic, and the southerly part is moving into the Caribbean, what else is new?
Member Since: August 30, 2008 Posts: 8 Comments: 2834

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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.