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 SQUAWK:


Aren't we supposed to be heading back into La Nina?


We could - there is a La Niña Watch in effect.
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Boy boy...I leave you guys for a year and I come back to shower curtains, trolls, grammar issues...nice to see some things never change :) I also noticed the crayons were left out at the NHC. Could be an interesting remainder of the season...
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Quoting tropicfreak:


Isn't it on the same frontal boundary as 95L?


Yes.
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Quoting kmanislander:


Last year was La Nina, this year is neutral. Two different set ups that will likely produce a different result this year. The troughs are unlikely to hang around the eastern Seaboard for all of the season.


Aren't we supposed to be heading back into La Nina?
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Quoting TropicalAnalystwx13:
My bets are on this becoming Invest 96L over the weekend.



Isn't it on the same frontal boundary as 95L?
Member Since: September 2, 2006 Posts: 110 Comments: 6878
Quoting HOTWHEELS99:
i agree with all the local weather channels here in florida they say we should have a similar pattern like last year with the east coast staying safe all season ( lets hope that is the case so far so good )
Hmmm... Guess it never hurts to hope. But who gave them the crystal ball?
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Quoting HOTWHEELS99:
i agree with all the local weather channels here in florida they say we should have a similar pattern like last year with the east coast staying safe all season ( lets hope that is the case so far so good )


Last year was La Nina, this year is neutral. Two different set ups that will likely produce a different result this year. The troughs are unlikely to hang around the eastern Seaboard for all of the season.
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Quoting TropicalAnalystwx13:
My bets are on this becoming Invest 96L over the weekend.





me too
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Quoting HOTWHEELS99:
dry air and wind shear should have 93 doing what emily did if it even makes it


Have you even looked at this....



93L is on the left. It is under 10-15 kt shear.

Doesn't look like dry air is anywhere near 93L either.



What have you got to say for yourself?
Member Since: September 2, 2006 Posts: 110 Comments: 6878
My bets are on this becoming Invest 96L over the weekend.

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95L

92L
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The arrangement of the circles in a tidy line is reminiscent of how hotspots move over time.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting MississippiWx:


95L could very easily be a TD at the 5pm update...still depends on warm-core/attachment to frontal boundary.
I completely agree. Appears to be the only thing stopping it from becoming a cyclone.

What we're seeing right now kinda reminds me of 2005 when we were seeing cyclones developing left and right in random locations.

*Gasp* I just made a 2005 comparison...sorry blog.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting BahaHurican:
Explains the no change in the NHC prognosis...

I gotta admit, this is the one of these four that I think has serious chances to do damage... 94L looks like it's setting up for some strange interaction w/ 92L; no knowing what's the deal until we see what happens w/ that... though position there is good enough to maybe impact stuff... depending on how the high shifts around...



The High will not let 93L recurve before 60W. By the time it reaches the Islands the high will stretch all the way back to the Bahamas. If 93L survives to develop into something the odds of striking the Islands from 14 N and higher look to me to be quite high. Beyond 60W it could be pretty much due West through the NW Caribbean or WNW close to Hispaniola. Way too early for that call.
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What happens if 92L and 94L get intertwined and slow down...then 93L comes up on the southern flank and gets involved? I'll try a poll.
Would that be a:
1. Fujiwara
2. Double Fujiwara
3. This isn't your grandma's fujiwara
4. Son of Fujiwara
5. make your own guess
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Quoting TropicalAnalystwx13:
What the heck happened in the Atlantic basin? We have Invest 92L, Invest 93L, Invest 94L, Invest 95L. Will we get an Invest 96L?

There is a really good chance that 95L becomes TD #6/Franklin sometime later on tonight or tomorrow. I'd give it a 90%/~100% chance.

There is a good chance that 92L becomes something over the weekend. I think the chances need to be slightly higher, near 60% or so. This will probably be a fish storm, since it won't be affecting anybody directly.

The chances for 93L are not as high as the first two, but still pretty high. 93L's poor appearance can be partly contributed to separating from the ITCZ. I'd give it about a 40% chance, just as the NHC has.

Lastly, Invest 94L is probably the least organized out of all four of the AOIs. It is disorganized and doesn't really have a good chance at developing within the next few days. I think the NHC nailed it with a 20% chance.




could we see some in like we saw back in july off the E ocast could that be come some in
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Quoting Tazmanian:






here your shower curtain



and with every shower curtain.. 'Here's yer SIGN!'
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What the heck happened in the Atlantic basin? We have Invest 92L, Invest 93L, Invest 94L, Invest 95L. Will we get an Invest 96L?

There is a really good chance that 95L becomes TD #6/Franklin sometime later on tonight or tomorrow. I'd give it a 90%/~100% chance.

There is a good chance that 92L becomes something over the weekend. I think the chances need to be slightly higher, near 60% or so. This will probably be a fish storm, since it won't be affecting anybody directly.

The chances for 93L are not as high as the first two, but still pretty high. 93L's poor appearance can be partly contributed to separating from the ITCZ. I'd give it about a 40% chance, just as the NHC has.

Lastly, Invest 94L is probably the least organized out of all four of the AOIs. It is disorganized and doesn't really have a good chance at developing within the next few days. I think the NHC nailed it with a 20% chance.
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Quoting KEEPEROFTHEGATE:


Oh, no, not again! KOG is having a bad day...infrastructure be damned!
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Quoting Stormchaser2007:


95L could very easily be a TD at the 5pm update...still depends on warm-core/attachment to frontal boundary.
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Quoting CorneliaMarie:
428. TampaTom 3:56 PM EDT on August 12, 2011 +0
First, our guest Troll speaks as if he can foretell the tropical future several weeks out...

Next, he goes ALL CAPS on us...

What's next? A shower curtain?



either that or tourettes syndrome....


En Espanol, of course...
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Going out to sea


Not going out to sea


Going out to sea


Going out to sea
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Hello to all "you nuts".....j/k (couldn't resist) :P You are otay in my book....I kinda like nutty folks.....

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Member Since: June 9, 2007 Posts: 4 Comments: 15923
First, our guest Troll speaks as if he can foretell the tropical future several weeks out...

Next, he goes ALL CAPS on us...

What's next? A shower curtain?
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Triple play...

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Quoting kmanislander:
I just love this blog, would make a good book LOL

Two things of current interest with 93L. The first is that it is now in an area of about 20 knots of shear and moving into a lower shear environment over the course of the next 24 horus. The second is that the 850 mb vorticity trails the surface feature by about 200 miles or so. Until that changes development will be real slow.

Conclusion ?. By tomorrow night it may start to look better
Explains the no change in the NHC prognosis...

I gotta admit, this is the one of these four that I think has serious chances to do damage... 94L looks like it's setting up for some strange interaction w/ 92L; no knowing what's the deal until we see what happens w/ that... though position there is good enough to maybe impact stuff... depending on how the high shifts around...

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Quoting MississippiWx:
92L has a vigorous mid-level circulation that could make its way down to the surface with a little help from convection later:




but 92L has got in march better looking
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Quoting JNCali:
So... when the polar ice all melts... granted we'll lose a bit of real estate,  but won't it be nice being able to drink all that ocean water since it will be fresh??


If the ice is already in the water it will not raise sea level that much (actually not at all). The additonal warmth allowed into the atmosphere due to less reflectivity will, however, allow for a substantial warming causing glacial melt and THAT will certainly increase sea level...as well as reduce the amount of potable water on the planet
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I just started my blog.. just so I can use the ignore list.. feeling guilty and giddy at the same time...
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Quoting Grothar:


Grothar, hey where u image has this storm isn't it just about where Emily was at one time?

sheri
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92L has a vigorous mid-level circulation that could make its way down to the surface with a little help from convection later:

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Quoting pottery:

You learn Fast, young Fellow.
Not bad for a guy in the middle of nowhere.... lol

Quoting Magical:
You people are nuts!
Nothing new there... lol... read ur PM... we'll still be here afterwards...
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Quoting Magical:
You people are nuts!
Giving 'nuts' a bad name
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Quoting tiggeriffic:


i like mine frozen with sliced strawberries


You're a strange and wondrous woman
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What is south of 95L? Pre-96L maybe?
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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.