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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Quoting HurricaneDean07:
Tropicfreak, lol
Yep, though 2 more storms this month likely wont happen, Maybe one more but anyhow that would put us at Jose and thats if everything works out with all of our current invests...


We also need to watch that area off the east coast and a wave that is about to emerge so yeah could be past Jose. Ok maybe I'm getting too far ahead of myself.
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Quoting Chucktown:


93 is the worst looking entity out of the 4 that we are following...


That's a good thing, since it is the only one likely to significantly threaten anybody if it develops. It's also a bad thing, because the weaker it is, if it does develop, it will be farther west, and more likely to impact land areas.
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Wow TD 6 formed, it formed early enough that it has a decent shot of making it to TS status before it is absorbed.
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Quoting nigel20:

I think 93L will move over an area of lower shear tomorrow.



and that when will see 93L geting here act togeter
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting HurricaneDean07:
Tropicfreak, lol
Yep, though 2 more storms this month likely wont happen, Maybe one more but anyhow that would put us at Jose and thats if everything works out with all of our current invests...


I know, I was kidding around with Taz.
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Quoting Chucktown:


93 is the worst looking entity out of the 4 that we are following...


Yes...but it still certainly has potential down the road.
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Quoting Chucktown:


93 is the worst looking entity out of the 4 that we are following...

I think 93L will move over an area of lower shear tomorrow.
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754. j2008
Quoting Chucktown:


93 is the worst looking entity out of the 4 that we are following...

Its also the one that has the most potential to do damage in the future.
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Tropicfreak, lol
Yep, though 2 more storms this month likely wont happen, Maybe one more but anyhow that would put us at Jose and thats if everything works out with all of our current invests...
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Quoting tropicfreak:


If we had 2 storms in the hot GOM waters then this blog will go crazy.



i like it when the blog gos nuts
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Not to mention TCHP is really high in the Caribbean:


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Quoting Tazmanian:



yup



so many things now we this need two storms in the gulf and there you have it


If we had 2 storms in the hot GOM waters then this blog will go crazy.
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a new ball is fring up with 92L
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting nigel20:

93L


93 is the worst looking entity out of the 4 that we are following...
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Out for now.........See yall later or tomorrow...
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Quoting AllStar17:
92L certainly seems to have some kind of circulation:
Link



of cores its dos or it will not be 92L right now
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting HurricaneDean07:
Forecast for TWO:
92L: 60%
93L: 40%
94L: 60%

Then at 10 PM Advisory:
Tropical storm Franklin
40 Mph ; 1008 MB
Moving ENE at 17 mph


Don't forget about that area off of NC.
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How does 94L have an ATCF, but not 92L?

They'll probably give 92L later on sometime.
Member Since: July 6, 2010 Posts: 113 Comments: 32822
Quoting Tazmanian:



yup



so many things now we this need two storms in the gulf and there you have it


Then we would have 8 storms to watch LOL. I knew the tropics got busy, but never seen it get this busy, looks like 2005 may see some competition.
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Forecast for TWO:
92L: 60%
93L: 40%
94L: 60%

Then at 10 PM Advisory:
Tropical storm Franklin
40 Mph ; 1008 MB
Moving ENE at 17 mph
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92L certainly seems to have some kind of circulation:
Link
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Quoting tropicfreak:


I agree taz could be marked a yellow circle at 10% at 8pm, may even be designated 96L later this evening as well.



yup



so many things now we this need two storms in the gulf and there you have it
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting Tazmanian:



can i have a link too the TCFA site plzs




that means we could see a high ch for 94L then


I agree taz maybe even TD 7 tonight.
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Quoting Tazmanian:
dont for get off the NC coast lol


I agree taz could be marked a yellow circle at 10% at 8pm, may even be designated 96L later this evening as well.
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93L
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Quoting Stormchaser2007:
TCFA went out for 94L.

Not sure if they'll actually post the message.



can i have a link too the TCFA site plzs




that means we could see a high ch for 94L then
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting MississippiWx:
The Atlantic is really challenging the Western Pacific to be the warmest basin in the world.



When talking anomalies, the Atlantic has the unanimous advantage in warmth in the Northern Hemisphere. Sure, we've only had tropical storms so far, but that is going to change.



is the warmest basin
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Quoting Stormchaser2007:
Really cooling down now.



Here is another graphic that shows the cooling of the Pacific,the subsurface waters.

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731. JLPR2
Wow, I have not checked the blog since yesterday and we have TD 6 from a 95L I didn't know existed. XD

And from the looks of it 94L is the most organized of the other three disturbances.
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TCFA went out for 94L.

Not sure if they'll actually post the message.
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A new tropical wave should move off Africa in a next day or two
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Quoting charlottefl:
Wow, shear is really low now across almost the entire basin, that could make for an interesting couple of months...



Don't forget high water temps. Get rid of the dry air and???
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Quoting charlottefl:
Wow, shear is really low now across almost the entire basin, that could make for an interesting couple of months...

interesting come on we are just getting started
Member Since: July 15, 2006 Posts: 178 Comments: 56059
We have Tropical Depression #6, north of Bermuda. Apparently the NHC thinks that it isn't on a front. It should be subtropical, but given the warm-core nature of the system, I won't argue about it getting the name "Franklin" which it is likely to do in an advisory or two.



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Quoting KEEPEROFTHEGATE:

T.C.F.A.
XX/INV/94L
MARK
25N/55W



Wow, TCFA. Likely to see the red crayon out again at 8pm.
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dont for get off the NC coast lol
Member Since: May 21, 2006 Posts: 5091 Comments: 115454
Quoting TropicalAnalystwx13:
Q: Will Tropical Depression Six make it to tropical storm status? If so, how strong?

A. Yes | 40 MPH
B. Yes | 45 MPH
C. Yes | 50 MPH
D. Yes | 60 MPH+
E. No

Q: Will Invest 92L become a tropical depression or stronger over the weekend? If no, then when?

A. Yes
B. No

Q: Will Invest 93L become a tropical depression or stronger over the weekend? If no, then when?

A. Yes
B. No

Q: Will Invest 94L become a tropical depression or stronger over the weekend? If no, then when?

A. Yes
B. No

Not so sure about 93L or 94L...We'll see.
c a a b
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Quoting Tazmanian:
dos anyone no if 92L have a close low ?


I don't think it does, but 94L probably has one.


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Wow, shear is really low now across almost the entire basin, that could make for an interesting couple of months...

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T.C.F.W
06L/TD/F/CX
MARK
34N/66W


T.C.F.A.
XX/INV/94L
MARK
25N/55W


POSS T.C.F.A.
XX/INV/93L
MARK
11.35N/30.30W


POSS T.C.F.A.
XX/INV/92L
MARK
18.85N/45.89W


Member Since: July 15, 2006 Posts: 178 Comments: 56059
By the 8pm advisory

93L 50%

94L 50%

92L 80%

by the 10pm advisory

TD 6 will become T.S. Franklin
Member Since: July 25, 2010 Posts: 0 Comments: 2751
I think 94L is moving wnw already but NAM Model still doesn't know. please someone tell him LOL !!!
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00z UWNMS liked 93L



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The Atlantic is really challenging the Western Pacific to be the warmest basin in the world.



When talking anomalies, the Atlantic has the unanimous advantage in warmth in the Northern Hemisphere. Sure, we've only had tropical storms so far, but that is going to change.

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Quoting bigwes6844:
I mean that is real what you are saying but i feel that we are getting closer to the peak of the season but we will have franklin,gert, harvey,and irene. Trust me we will see jose and katia right after those 4 develop and 2005 will be caught up too somewat. But the writings are on the wall for these 4 storms. so by the beginning of next week we will see all 4 named storms in the atl.


i can say i think we will have gert and harvey out of the 4 but i just dont know about irene
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Q: Will Tropical Depression Six make it to tropical storm status? If so, how strong?

A. Yes | 40 MPH
B. Yes | 45 MPH
C. Yes | 50 MPH
D. Yes | 60 MPH+
E. No

Q: Will Invest 92L become a tropical depression or stronger over the weekend? If no, then when?

A. Yes
B. No

Q: Will Invest 93L become a tropical depression or stronger over the weekend? If no, then when?

A. Yes
B. No

Q: Will Invest 94L become a tropical depression or stronger over the weekend? If no, then when?

A. Yes
B. No

Not so sure about 93L or 94L...We'll see.
Member Since: July 6, 2010 Posts: 113 Comments: 32822
Quoting Tazmanian:



maybe am giveing 94L a 50 too 60% ch at 8pm



what do you see with 92 and 93L and when you think 93L will get it act togeter and get in the game with the rest?



I agree taz, 60% at 8pm. May even warrant a renumber later on in the evening.
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18z GFS running now...

0hrs.


6hrs.
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Quoting Patrap:
Im betting on 99L reaching the GOMEX,

,,,just saying


pre 99l needs to be closely watched
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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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