Four invests in the Atlantic; fair weather in Arctic to drive rapid sea ice loss

By: Dr. Jeff Masters , 3:38 PM GMT on August 12, 2011

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It's a busy day in the tropical Atlantic, with the National Hurricane Center tracking four areas of interest (Invests.) None of these systems is a danger to any land areas over the next three days. The disturbance of most concern is the one farthest from land, a tropical wave that emerged from the coast of Africa two days ago. This wave, (Invest 93L), is located about 500 miles southwest of the Cape Verde Islands, and is moving westward at 15 - 20 mph. Recent visible satellite loops show that 93L has lost some of its heavy thunderstorms since yesterday, and the system is poorly organized, though there is a good deal of spin to the system. There is dry air to its north that is interfering with development. The SHIPS model and University of Wisconsin CIMSS wind shear analysis are showing high wind shear in excess 20 knots affecting 93L, which has undoubtedly contributed to the storm's loss of organization. Sea surface temperatures are 27.5°C, which is one degree above the 26.5°C threshold usually needed to support a tropical storm.


Figure 1. Morning satellite photo of the four Invests in the Atlantic today.

Forecast for 93L
High wind shear above 20 knots is predicted along 93L's path through Saturday afternoon, followed by a drop to the moderate range, 10 - 20 knots, for the succeeding four days. This should allow the storm to organize over the weekend. The latest 00Z and 06Z model runs of the four best models for predicting tropical storm formation (GFS, ECMWF, NOGAPS, and UKMET), have only one model, the GFS, that is indicating significant development of 93L. This model brings 93L near the northern Lesser Antilles Islands by Wednesday. NHC gave 93L a 40% chance of developing into a tropical depression by Sunday morning in their 8am outlook. Given 93L's recent struggles, I'd put these odds at 30%.

92L
An African wave midway between the northern Lesser Antilles Islands and the coast of Africa, near 18°N 45°W, is moving west-northwest at 20 mph. This system, (Invest 92L), is being given a 40% chance of development by NHC. Recent visible satellite loops show a modest amount of heavy thunderstorm activity, but no signs of a surface circulation. A Windsat pass from 8:04 am EDT this morning also showed no surface circulation, and noted top winds of around 35 mph. Water vapor satellite loops show that a large area of dry air surrounds 92L, and this dry air is causing problems for the storm. The SHIPS model and University of Wisconsin CIMSS wind shear analysis are showing moderate wind shear of 10 - 20 knots affecting 92L. Sea surface temperatures are 27 - 27.5°C, which is a degree above the 26.5°C threshold usually needed to support a tropical storm.

Forecast for 92L
Moderate wind shear of 10 - 20 knots is predicted along 92L's path over the coming five days, which should allow the storm to organize if it can handle the dry air surrounding it. The latest 00Z and 06Z model runs of the four best models for predicting tropical storm formation (GFS, ECMWF, NOGAPS, and UKMET) show weak development or no development of 92L, and NHC gave 92L a 40% chance of developing into a tropical depression by Sunday morning in their 8am outlook. A steady west-northwest motion for 92L is predicted by all of the models, which should make the storm miss the Lesser Antilles by a comfortable margin. However, Bermuda may be at risk from 92L next week.

94L
A broad low pressure system about 700 miles northeast of the northern Lesser Antilles Islands has developed a small amount of heavy thunderstorm activity, and may be a threat to become a tropical depression early next week. This system, (Invest 94L), is currently headed west-southwest at 10 mph, but is expected to turn northwest later today. Recent visible satellite loops show some spin to the cloud pattern at middle levels of the atmosphere, but no signs of a surface circulation. This system is also battling dry air, which is keeping the its heavy thunderstorms relatively meager. The SHIPS model is showing moderate wind shear of 10 - 20 knots affecting 94L. Sea surface temperatures are 28°C.

Forecast for 94L
Moderate wind shear of 10 - 20 knots is predicted along 94L's path over the coming five days, which should allow slow development, if it can handle the dry air surrounding it. None of our reliable models for predicting tropical storm formation (GFS, ECMWF, NOGAPS, and UKMET) show no development of 94L, and NHC gave 94L just a 20% chance of developing into a tropical depression by Sunday morning in their 8am outlook. Bermuda is the only land area that needs to be concerned with 94L.

95L
The final invest out there is an area of disturbed weather along on old frontal boundary several hundred miles off the coast of North Carolina. This sytem, Invest 95L, is headed northeastwards out to sea, and is not a threat to any land areas.



Figure 2. Arctic sea ice extent on August 11, 2011, was the 2nd lowest on record for the date. The Northeast Passage and Northwest Passage (southern route) were both ice-free. Image credit: UIUC Cryosphere Today.

Arctic sea ice poised to undergo record decline in mid-August
A strong high pressure system with a central pressure of 1035 mb has developed over the Arctic north of Alaska, and will bring clear skies and warm southerly winds to northeast Siberia and the Arctic during the coming week, accelerating Arctic sea ice loss. Widespread areas of northeastern Siberia are expected to see air temperatures 4 - 12°C (7 - 22°F) above average during the coming week, and the clockwise flow of air around the high pressure system centered north of Alaska will pump this warm air into the Arctic. Arctic sea ice extent, currently slightly higher than the record low values set in 2007, should fall to to its lowest extent for the date by the third week of August as the clear skies and warm southerly winds melt ice and push it away from the coast of Siberia. This weather pattern, known as the Arctic Dipole, was also responsible for the record sea ice loss in 2007, but was stronger that year. The weather conditions that led to the 2007 record were quite extreme--one 2008 study led by Jennifer Kay of the National Center for Atmospheric Research showed that 2007's combination of high pressure and sunny skies in the Arctic occur, on average, only once every 10 - 20 years. The 2011 summer weather pattern in the Arctic has not been nearly as extreme as in 2007, but the total sea ice volume has declined significantly since 2007, leading to much loss of old, thick, multi-year ice, making it easier to set a new low extent record with less extreme weather conditions. The GFS model is predicting that the Arctic Dipole will weaken by 8 - 15 days from now, with cloudier weather and weaker high pressure over the Arctic. This should slow down the rate of Arctic sea ice loss to very near the record low values observed in 2007. It remains to be seen if 2011 Arctic sea ice extent will surpass the all-time low set in September 2007; it will be close, and will depend on the weather conditions of late August and early September, which are not predictable at this time. It is already possible to sail completely around the North Pole in ice-free waters through the Northeast Passage and Northwest Passage, according to sea ice maps maintained by the UIUC Cryosphere Today website. This marks the fourth consecutive year--and the fourth time in recorded history--both of these Arctic shipping routes have melted free. Mariners have been attempting to sail these passages since 1497. This year, the Northeast Passage along the north coast of Russia melted free several weeks earlier than its previous record early opening.

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Jeff Masters

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1711. SLU
Quoting Tazmanian:







i dont call this better looking to me
Quoting tropicfreak:





??????


The circulation is better defined now than it was at first light this morning. Deep convection is still lacking but there signs of development.
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Quoting Joanie38:
Hello everyone:) So what is the outlook for 93L? I keep hearing it might go into the GOM..is this a possibility?

TIA :)



un less 93L starts geting it act togeter wish is vary weak right now in fac i dont even think there a low lift with it any more all so i think its a open wave it olny has a 10% ch right now
Member Since: May 21, 2006 Posts: 5091 Comments: 115439
Quoting charlottefl:


I would mount it on the roof, but it's surrounded by large oak trees, it's on a post in an open field across the street right now. So at least it's in the open. I'm gonna take a look at it again today and see if I can't figure something out.
Just sounds like you need a longer pole. Should be able to get something 11/12 ft long, mount and wire it up, then dig out the 2 ft to stabilize...

Member Since: October 25, 2005 Posts: 19 Comments: 22687
1708. usa777
Quoting Joanie38:
Hello everyone:) So what is the outlook for 93L? I keep hearing it might go into the GOM..is this a possibility?

TIA :)

93 is looking rough this morning
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93L's other problem is his enemy 92L, which because something (that line SW of 92L) is connecting both of them.
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Quoting charlottefl:
Ok everyone, I have a question, maybe a little off topic, but weather related. I have a anemometer that's mounted at about 5 ft, cause I haven't been able to figure out a permanent way to mount it higher as of right at the moment. Is there any way to take the readings it's recording and adjust based on the height, or is it too much guess work. I'll get it mounted higher later on it's just a matter of finding the right spot.

charlottefl...I have mine at 20ft and sometimes the wind is stronger at ground level than up at 20ft.
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Quoting Tazmanian:







i dont call this better looking to me


I agree with you taz, it looks pretty bbad but the other guy does have a point it looks like a nice coc
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Hello everyone:) So what is the outlook for 93L? I keep hearing it might go into the GOM..is this a possibility?

TIA :)
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Quoting SLU:
94L is getting better defined and the center appears to be tightening up. I needs more deep convection to be called a TD. Meanwhile 92L is in very bad shape now.

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i dont call this better looking to me
Member Since: May 21, 2006 Posts: 5091 Comments: 115439
1702. lhwhelk
Quoting cajunkid:
glad to see Texas is getting "some" rain
Not in the Brazosport area. At this point, even 2-3 inches wouldn't make any difference at all. We really need a minor tropical storm, or maybe some training. NOTHING major, please.
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Quoting hydrus:
The vorticity 850mb shows the South Florida blob spinning up quick...Link


split off from 94 l???
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1700. msphar
Sorry, I was remembering Iniki from memory and 1992 was a long time back in the memory banks.
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Quoting hydrus:
I lived on Kings Highway then..That storm tore us apart and almost killed my neighbors...Super bad day
My folks have a house on Manasota key and were spared. Just 20 miles north and they would have been like North Captiva. Split in two.
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Quoting charlottefl:


Yeah, we were at St. Joseph's, and it pretty much destroyed the hospital...
Was then and still 1 mile from exit 170 off kings hwy only scars left are dead trees snapped in half
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Quoting GTcooliebai:
Yep, I wonder what is the record for most Hurricanes in a row over there?

I think 8 consecutive hurricanes in 1992 is the record.
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Quoting tropicfreak:



Remember that troughs aren't as strong in the summer. This isn't October, it's August.


Well not necessarily. Keep in mind that the trough pattern is strong this year, similar to the last few years. It all depends on what's dominant. In this case most of this summer the trough has been dominant, as we head into September, the trough will likely only be stronger.

However, its like the trough is constantly in control, we have has brief periods where the high bridges across far enough to where a tropical cyclone could threaten the Southeast if one where present at the time. As the number of systems increases as we head into September, it does increase the chance of a landfall in the Southeast U.S. However keep in mind that with the trough being overall more dominant this year again. I would say the chances of landfalling hurricanes is lower than normal comparatively speaking for how active the season will be in terms of numbers. I believe Florida has a particularly lower than normal chance of a hurricane landfall.

Now, I am not saying no hurricanes will make landfall this year like last year. I'm just saying, they are lower than normal. However, I would say they are at least a bit higher than last year anyway.
Member Since: August 21, 2008 Posts: 0 Comments: 7993
Atlantic update

Fish - Fish - Fish - Fizzle
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Quoting CybrTeddy:


I don't think so, 94L is encountering pretty good shear and getting dry air blasted into its core right now.



Quoting SLU:
94L is getting better defined and the center appears to be tightening up. I needs more deep convection to be called a TD. Meanwhile 92L is in very bad shape now.

Image and video hosting by TinyPic


??????
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Quoting hydrus:
I lived on Kings Highway then..That storm tore us apart and almost killed my neighbors...Super bad day


Yeah, we were at St. Joseph's, and it pretty much destroyed the hospital...
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TS Franklin developed today from the disturbance over the Gulf Stream that by yesterday, was under the warmest water of all four invests. The exceptional heat of the Gulf will continue to fuel a high potential for tropical storm generation over this portion of the North Atlantic and the possibility of extratropical storms downstream in Europe.
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1690. Grothar
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1689. hydrus
Quoting wayne0224:
Was not a fun day in Charlotte county as I lost everything. agree no major landfalls.
I lived on Kings Highway then..That storm tore us apart and almost killed my neighbors...Super bad day
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glad to see Texas is getting "some" rain
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1686. SLU
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1685. Dennis8
?
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Quoting EYEStoSEA:
That area east of Nicaragua looks suspicious....
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Quoting wayne0224:
None that i know of Mine is 10ft above the peak of my roof using 2in clamps and a rigid pipe dowel.


I would mount it on the roof, but it's surrounded by large oak trees, it's on a post in an open field across the street right now. So at least it's in the open. I'm gonna take a look at it again today and see if I can't figure something out.
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Quoting msphar:
Part of the problem is that it has to hang together for something like 33 degrees of Westing and good bit of Northing. Its located at 122W currently. Hilo is at 20N 155W That is a long run for any storm. Plus the water temp and then the twin towers of Kea and Loa helping to deflect. Then the rest of the islands curve Northwest from there.

Storms have reached these but it is rare. There was one back in the 80s, Iniki I think it was called and it devastated the garden island (Kauai) but it was a major storm to hang together for that long distance.


Iniki occured in the early 90s.
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Quoting EYEStoSEA:


TY, Baha :)


Thx to you both! :<)
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Quoting charlottefl:
Ok everyone, I have a question, maybe a little off topic, but weather related. I have a anemometer that's mounted at about 5 ft, cause I haven't been able to figure out a permanent way to mount it higher as of right at the moment. Is there any way to take the readings it's recording and adjust based on the height, or is it too much guess work. I'll get it mounted higher later on it's just a matter of finding the right spot.
None that i know of Mine is 10ft above the peak of my roof using 2in clamps and a rigid pipe dowel.
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Quoting 12george1:

Well, coincidentally, the Atlantic has had 6 consecutive tropical storms.
Yep, I wonder what is the record for most Hurricanes in a row over there?
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Quoting tropicfreak:


A

Could quite possibly become a hurricane.
best chance of being a major so far
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Quoting Bobbyweather:

So I guess 94L is not going to form anytime soon?


I don't think so, 94L is encountering pretty good shear and getting dry air blasted into its core right now.
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1676. msphar
Part of the problem is that it has to hang together for something like 33 degrees of Westing and good bit of Northing. Its located at 122W currently. Hilo is at 20N 155W That is a long run for any storm. Plus the water temp and then the twin towers of Kea and Loa helping to deflect. Then the rest of the islands curve Northwest from there.

Storms have reached these but it is rare. There was one back in the 80s, Iniki I think it was called and it devastated the garden island (Kauai) but it was a major storm to hang together for that long distance.
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Good morning, everyone.
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1674. hydrus
The vorticity 850mb shows the South Florida blob spinning up quick...Link
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1673. SLU
94L is getting better defined and the center appears to be tightening up. I needs more deep convection to be called a TD. Meanwhile 92L is in very bad shape now.

Image and video hosting by TinyPic
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1672. ackee
I have seen what happen to 93L sometimes happen to some system before condtion are right but system just falls apart can never predict mother Nature
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There is almost nothing left of 93L:
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Quoting BahaHurican:
Jeanne, IIRC, was following a trough out, lost the steering [Nward] and then got pushed west by the re-expanding high. That was one scenario that the models were considering with Emily, may she rest forever....

This situation is a bit different.


TY, Baha :)
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Quoting PGIgirl:
I can't believe I almost forgot Charlie. 7 years ago today the eye of that guy passed directly over my house in PGI. Took landscaping, pool cage, roof tiles and a strip of gutter, but left the house intact and dry. Wisely we had "got the he__ out"! Thank you State of Florida for the "post-Andrew" building codes! Anything built after those were enforced pretty much held together when the winds were clocked at 145 knots at the airport just east of our house. Please no major landfalls anywhere this year.
Was not a fun day in Charlotte county as I lost everything. agree no major landfalls.
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Quoting GTcooliebai:
Now watch them get a Hurricane to make it 6 straight.

Well, coincidentally, the Atlantic has had 6 consecutive tropical storms.
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Ok everyone, I have a question, maybe a little off topic, but weather related. I have a anemometer that's mounted at about 5 ft, cause I haven't been able to figure out a permanent way to mount it higher as of right at the moment. Is there any way to take the readings it's recording and adjust based on the height, or is it too much guess work. I'll get it mounted higher later on it's just a matter of finding the right spot.
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93L is vary weak at this time all most look like a open wave
Member Since: May 21, 2006 Posts: 5091 Comments: 115439
1665. IKE

Quoting ackee:
Iam trying to figure what going on with 93L shear seem very low DIR air seem to somewhat of a factor but system just seem have even lost its spin think NHC need deactivate 93L for now just my view
93L does look like it's heading to deactivation.
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1664. Thrawst
Quoting WeatherNerdPR:
Eww, 94L is naked...


PUT some clothes ON!
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Quoting CybrTeddy:
Looking at 94L, 92L, and 93L.. its almost impossible to tell which one might become Gert first they are all really disorganized this morning. Basing this entirely off model support, but I'd stick my neck out slightly for 92L to become Gert then 93L becoming Harvey next week. There's an equally likely chance 92L won't develop and 93L will become Gert and vice versa.

So I guess 94L is not going to form anytime soon?
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1662. hydrus
CMC has a small low hitting South Florida and 93 heading toward Jamaica.Link
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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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