First tropical depression of the season may form from 92L

By: Dr. Jeff Masters , 3:38 PM GMT on June 13, 2010

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An unusually large and well-developed African tropical wave for so early in the season has developed midway between the coast of Africa and South America. The storm was designated Invest 92L by the National Hurricane Center yesterday, and has a good chance of becoming the first tropical depression of the Atlantic hurricane season. Surface winds measured by the 8:23am EDT pass of the European ASCAT satellite revealed that 92L already has a closed surface circulation, though the circulation is large and elongated. Top winds seen by ASCAT were about 25 mph. METEOSAT visible satellite loops show a large and impressive circulation that is steadily consolidating, with spiral bands building inward towards center, and upper-level outflow beginning to be established to the northwest and north.


Figure 1. Morning satellite image of Invest 92L.

Climatology argues against development of 92L, since only one named storm has ever formed between Africa and the Lesser Antilles Islands in the month of June--Tropical Storm Ana of 1979 (Figure 2). However, sea surface temperatures (SSTs) underneath 92L are an extremely high 28 - 30°C, which is warmer than the temperatures reached during the peak of hurricane season last year, in August - September. In fact, with summer not even here, and three more months of heating remaining until we reach peak SSTs in the Atlantic, ocean temperatures across the entire Caribbean and waters between Africa and the Lesser Antilles are about the same as they were during the peak week for water temperatures in 2009 (mid-September.) While 92L will cross over a 1°C cooler patch of water on Monday, the storm will encounter very warm SSTs of 28-29°C again by Tuesday.

The disturbance doesn't have to worry about dry air--Total Precipitable Water (TPW) loops show a very moist plume of air accompanies 92L, and water vapor satellite loops show that the center of 92L is at least 300 - 400 miles from any substantial areas of dry air. The 60-day cycle of enhanced thunderstorm activity called the Madden-Jullian Oscillation is currently favoring upward motion over eastern tropical Atlantic, and this enhanced upward motion helps create stronger updrafts and higher chances of tropical cyclone development.


Figure 2. Tropical Storm Ana of 1979 was the only June named storm on record to form between Africa and the Lesser Antilles Islands.

The forecast for 92L
A major issue for 92L, like it is for most June disturbances, is wind shear. The subtropical jet stream has a branch flowing through the Caribbean and tropical Atlantic north of 10° N that is bringing 20 - 40 knots of wind shear to the region. Our disturbance is currently located at 7°N, well south of this band of high shear, and is only experiencing 5 - 15 knots of shear. This moderate amount of shear should allow for some steady development of 92L over the next few days as it tracks west-northwest at 10 - 15 mph. The National Hurricane Center is giving 92L a medium (30% chance) of developing into a tropical depression by Tuesday morning. Based on visible satellite imagery over the past few hours, I believe this forecast is not aggressive enough, and that 92L has a 50% chance of developing into a tropical depression by Tuesday morning. Another factor holding 92L back is its proximity to the Equator. I would give 92L higher chances of developing if it were not so close to the Equator. The system is organizing at about 7°N latitude, which is so close to the Equator that it cannot leverage the Earth's spin much to help it get spinning. It is quite unusual for a tropical depression to form south of 8°N latitude.

The farther south 92L stays, the better chance it has at survival. With the system's steady west-northwest movement this week, 92L should begin encountering hostile wind shear in excess of 30 knots by Thursday, which should be able to greatly weaken or entirely destroy the storm before it gets to the Lesser Antilles Islands. However, residents of the islands--particularly the northern Lesser Antilles--should follow the progress of 92L closely, and anticipate heavy rains and high winds moving through the islands by Saturday or Sunday next weekend. The GFDL and HWRF models are predicting that 92L will develop into a moderate strength tropical storm that will then be weakened or destroyed by the end of the week, before it reaches the islands. This looks like a reasonable forecast.


Figure 3. The departure of sea surface temperature (SST) from average for June 10, 2010. Image credit: NOAA/NESDIS.

Oil spill wind forecast
There is little change to the oil spill wind forecast for the coming two weeks. Light winds of 5 - 10 knots mostly out of the south or southeast will blow in the northern Gulf of Mexico all week, according to the latest marine forecast from NOAA. These winds will keep oil near the coast of Louisiana, Alabama, Mississippi, and the extreme western Florida Panhandle, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range 8 - 16 day forecast from the GFS model indicates a typical summertime light wind regime, with winds mostly blowing out of the south or southeast. This wind regime will likely keep oil close to the coastal areas that have already seen oil impacts over the past two weeks.

Jeff Masters

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2347. KEEPEROFTHEGATE (Mod)
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2346. hercj
Quoting StormW:


LOL! That's an old pic of me...I've since shaved it off! Much easier to take care of.

Yep
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2345. KEEPEROFTHEGATE (Mod)
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2344. ACEhigh
Quoting sailingallover:


It's VERY broad... almost sub tropical even. 10 degrees in diameter!! The center of circulation is over a degree in diameter. Thats huge for a tropical storm. I don't think this can be stressed enough because all that rotating air has a tremendous amount of energy. 92L is not about convection although there is a lot of good convection. You just can't tell because the whole thing is so big it does not look like there is much going on. The burst occurring now just north of the center is as big as most TS's get!!! Right now 92L with it's bands would cover the ENTIRE Caribbean basin.


There is absolutely nothing even remotely subtropical about this system. It has a very large circulation because it arose from a monsoonal trough, similiar to the genesis of many wpac systems. it is DEEPLY tropical!
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2343. gator23
Quoting indianrivguy:


idiots

who is?
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2342. Dakster
Quoting gator23:

It should be called Bacardi Stadium at Burger King field when its done. At least name it for local companies.


Don't forget, paid for on the backs of local tax payers too.
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Quoting Baltimorebirds:
It probally be a tropical storm,and future bonnie should be right in behind it.


ok
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
Quoting gator23:

No GOM for the storm, Hello central America



I don't agree with you now...LOOKS LIKE A GOM event coming! IMO the high will move East allow the storm to come up the West side of the HIGH.....the high will not stay in that position for the entire time.
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Quoting Tazmanian:




i hop i win the best bloger Award
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
Quoting Dakster:


Yes. Although that was 10 names ago... My late grandmother used to call it Joe Robya Stadium. (Because of how expensive everything was/is)


I still do.. I am a serious Dolphin fan.

Zoo great to see you!
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2335. hercj
Quoting StormW:


LOL! Not yet! But if it helps, he and I have the same haircut.

As do I senior.
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2334. cg2916
Quoting MiamiHurricanes09:
Damn you keep catching all the errors, lol. AM.


LOL
Member Since: December 21, 2007 Posts: 13 Comments: 3046
2333. gator23
Quoting Dakster:


It's a good thing we got the new Marlin's stadium - now we can build name recognition. (j/k)

It should be called Bacardi Stadium at Burger King field when its done. At least name it for local companies.
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2331. Dakster
Quoting StormW:


LOL! Not yet! But if it helps, he and I have the same haircut.



Hmmm. Better stay out of South(east) Florida then. Just to be safe.
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Quoting CaneWarning:
The Tony Awards are on folks.




i hop i win the best bloger Award
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
2329. cg2916
Quoting StormW:


LOL! Not yet! But if it helps, he and I have the same haircut.


What haircut? LOL, just messing with you, Storm.
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Ref 2234 go Marlins
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I am not really worried about 92L right now. I am hoping that shear will take care of it down the road. But what does concern me is how early a system is forming so far out in the Atlantic. Gives me a eerie feeling for the rest of the season.
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Wanna know what is really frieghtning! With the strenght of the LOWs rolling off of Africa in about 2 weeks we will get the wonderful world of MJO into the Atlantic Basin.....LOOK AT...the Rough road is just beginning.
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Quoting gator23:

I can guarantee that especially since Dade County doesnt exist anymore. They Changed the name back in 1996 to Miami-Dade County


idiots
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Quoting cg2916:


1:00 AM or PM?
Damn you keep catching all the errors, lol. AM.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2322. Dakster
Quoting gator23:

I will refrainf from asking, but while your at it you might as well call it the Fair the Dade County Youth Fair and Bayside Marketplace by the old name of Pier 6 and the Port of Miami Dodge Island.


Pretty much... Although I would call it "Bayside". The other's are terms still used today. In fact, very recent maps still have the port listed as Dodge Island.

Care to go to the old City of Islandia?
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i say if it was not for the vary warm sea temper 92L will not be has we are seeing it
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
Note: It IS a closed center of circulation and by definition a TD. I'm not arguing that!!
Member Since: September 1, 2009 Posts: 23 Comments: 1007
60% chance of tsf...AOI is red now as of 8pm
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The Tony Awards are on folks.
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2317. gator23
Quoting TampaSpin:



This Steering Layer should leave no doubt where 92L is going.....GEEESSHHHH!

No GOM for the storm, Hello central America
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2316. amd
Quoting IKE:


Especially the area he had circled....western Caribbean...extreme southern GOM...


I'm not sure if 92L will be an organized system by the time it reaches that region, but he did say something extremely important in that video.

The strong high in the central high has been replaced by a strong trough, and the strong high is now ne of the Azores. This means that as long as that high is near the Azores, more and more waves will be able to enter the Caribbean and avoid south America.

Big High now no longer in the central atlantic
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2315. cg2916
Quoting MiamiHurricanes09:
Hourly Update On 92L - 8:00 PM Update



The National Hurricane Center (NHC) have upgraded their chances of possible tropical cyclone formation probability in the next 48 hours to 60%, which can be labeled as "high". Although it is clearly evident using satellite imagery that a tight, consolidated low has developed the National Hurricane Center (NHC) continues to use terms to describe it such as "large" and "broad".

92L continues to lose convection due to the Diurnal Minimum (D-MIN) but has began to develop small pockets of strong thunderstorms over the past hour or so. This trend should stop completely and reverse itself at around 1:00 PM EDT. I believe there is still a very high chance, almost 100%, that 92L will become a tropical depression.

-MiamiHurricanes09



1:00 AM or PM?
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Quoting Drakoen:
Hopefully we will get an Ascat pass.. Crucial...


It was closer than this mornings, but I don't know on which side it will be.

This morning:
2010/06/13 12:23:33 METOP-A 684 (km)

This evening:
2010/06/13 23:27:43 METOP-A 569 (km)
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i be gone for 4 days camping cant wait too see what 92L dos in 4days from now
Member Since: May 21, 2006 Posts: 5091 Comments: 115244
Quoting MiamiHurricanes09:
Aghhhh! I'm going to pull my hair out. It's evident that there is a consolidated closed low and they keep calling it "broad". Plus they contradicted themselves again calling the low "broad" in the TWD and "large" in the outlook.


It's VERY broad... almost sub tropical even. 10 degrees in diameter!! The center of circulation is over a degree in diameter. Thats huge for a tropical storm. I don't think this can be stressed enough because all that rotating air has a tremendous amount of energy. 92L is not about convection although there is a lot of good convection. You just can't tell because the whole thing is so big it does not look like there is much going on. The burst occurring now just north of the center is as big as most TS's get!!! Right now 92L with it's bands would cover the ENTIRE Caribbean basin.
Member Since: September 1, 2009 Posts: 23 Comments: 1007
Quoting Drakoen:
Hopefully we will get an Ascat pass.. Crucial...
Agree 100%.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting taco2me61:

Yes and No
Yes it could come toward the Gulf but it is about 10 days away from that and has alot of shear ahead of it... You see it would have to follow the southernly track for it to make it that far and with the "Hot" waters that are there all I can say is watch out... Now if it follows a more Northerly track it could end it because of to much shear. So on that note we need to just wait and see which way this one will head to....
I hope I was able to help

Taco :o)

thanks!
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The models are not very good at direction until the system has developed, and the initial point is used. Not only that - any model more than five days off has an error rate of about 80%. Its far to early to look at the path after the next 2-3 days with any certainty.
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2306. cg2916
Quoting Hurricanes101:


storms dont develop out in the Atlantic in June, so there really is no way of knowing based on the past what will happen

Well, this whole time, it's been against climatology, why stop now?
Member Since: December 21, 2007 Posts: 13 Comments: 3046
2305. IKE
Quoting cg2916:
Hey, IKE, this blog is getting really interesting and I'm running out of popcorn, could you send me some?


LOL.
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This Steering Layer should leave no doubt where 92L is going.....GEEESSHHHH!
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2303. Dakster
Quoting zoomiami:


I would like to know how they ever expect to build name recognition when the name changes every 10 months.


It's a good thing we got the new Marlin's stadium - now we can build name recognition. (j/k)
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I'm back.

Wow! 500 posts since 6:30!
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Hourly Update On 92L - 8:00 PM Update



The National Hurricane Center (NHC) have upgraded their chances of possible tropical cyclone formation probability in the next 48 hours to 60%, which can be labeled as "high". Although it is clearly evident using satellite imagery that a tight, consolidated low has developed the National Hurricane Center (NHC) continues to use terms to describe it such as "large" and "broad".

92L continues to lose convection due to the Diurnal Minimum (D-MIN) but has began to develop small pockets of strong thunderstorms over the past hour or so. This trend should stop completely and reverse itself at around 1:00 AM EDT. I believe there is still a very high chance, almost 100%, that 92L will become a tropical depression.

-MiamiHurricanes09

Member Since: September 2, 2009 Posts: 130 Comments: 21194
2299. cg2916
Hey, IKE, this blog is getting really interesting and I'm running out of popcorn, could you send me some?
Member Since: December 21, 2007 Posts: 13 Comments: 3046
Quoting Hurricanes101:


storms dont develop out in the Atlantic in June, so there really is no way of knowing based on the past what will happen

all the models have this thing going into the Caribbean or in that general direction. once it gets there where else can it go but in the gulf or to the epac. i can't see it going to the Caribbean and then making a sharp turn to the east coast. but i don't know too much about this stuff. does it seem likely that this storm or wave will take the path that the models have it on?
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2297. ACEhigh
Quoting 1900hurricane:
Out of curiosity, I have always wondered why it is called a Durinal Minimum and Durinal Maximum. Shouldn't it technically be called the Durinal Minimum and Nocturnal Maximum, since the max occurs at night?


First off, its "diurnal", and the name refers to daily cycles- it is the same for tides i.e. diurnal tides are one high and one low/day, semi diurnal are two high and two low...
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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.