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 TropicalAnalystwx13:
It'll be a tough decision for the NHC for whether or not to declare TD Six Franklin. It has lost its organization over the past few hours.





Hardly "tough" if you ask me.
Member Since: Posts: Comments:
1109. KEEPEROFTHEGATE (Mod)



ENTER STAGE RIGHT
Member Since: July 15, 2006 Posts: 163 Comments: 52197
Quoting Thunderpig75:


I've heard that fireballs (meteors with a downward trajectory) are something you only see once per lifetime. I saw one about 15 years ago. Scared the heck out of me for the next 5 minutes until the world didn't end.


yea...I saw one as a teenager.....scared thew snot outta my cousin and me...
Member Since: August 13, 2007 Posts: 0 Comments: 10458
Quoting spathy:


Yep
Oss
Thanks Baha
Did he do it again this year?
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It'll be a tough decision for the NHC for whether or not to declare TD Six Franklin. It has lost its organization over the past few hours.



Member Since: July 6, 2010 Posts: 108 Comments: 30241
34.8n66.8w, 35.6n64.7w have been re-evaluated&altered for TD.6's_12amGMT_ATCF
34.7n66.7w, 35.5n64.7w, 36.1n62.3w are now the most recent positions

Starting at 12August_12amGMT and ending at 13August_12amGMT

The northernmost line-segment is the straightline projection

TropicalDepression6's travel-speed was 23.5mph(37.8k/h) on a heading of 72.2degrees(ENE)
Using straightline projection of the travel-speed&heading derived from the ATCF coordinates for 6pmGMT then 12amGMT :
TD.6 was headed toward passage over Graciosa(Azores)Portugal ~3days6hours from now

Copy&paste 32.5n70.6w, 33.6n68.8w, 34.7n66.7w, 35.5n64.7w-36.1n62.3w, meo, bda, flw, grw, 35.5n64.7w-38.95n27.966w into the GreatCircleMapper for more info

The previous mapping (for 12August_12pmGMT)
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Quoting InTheCone:


Just popping out of lurkdom while it is slow to say that I really enjoy your posts! Hope you stick around - ty!
thanks.

Why you lurkin though? No need to hide lol
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Quoting justsouthofnola:
long time lurker here.....

anyone have a link for the latest gfs loop
or euro


Yep.
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Quoting presslord:
George Noory is discussing the recent epidemic of red/yellow/orange fireballs seen streaking across the skyLink


I've heard that fireballs (meteors with a downward trajectory) are something you only see once per lifetime. I saw one about 15 years ago. Scared the heck out of me for the next 5 minutes until the world didn't end.
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Quoting JrWeathermanFL:
How many names does Jason have?!?!? I already have deleated 7!




i have 34 have jason names
Member Since: May 21, 2006 Posts: 5089 Comments: 114048
Quoting bigwes6844:
Kori let me ask you something, The cold front that is supposed to come down south this weekend. Do you see it stalling out in the GOM and developing? Or anyone else can help me out with it.


Well, about three days ago, the GFS was indicating the possibility of a trough split, so it's something to keep an eye on for sure (although it has since backed off on that solution).

I personally think it will be entirely inconsequential, however, as the associated singular energy, if there is one, is very weak within the models. Nonetheless, it might move slow enough underneath the ridge so that it least warrants attention.
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Quoting KEEPEROFTHEGATE:
06L/TD/F/CX
MARK
36N/61W


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


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


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



Invest 92L does not have a TCFA.
Member Since: July 6, 2010 Posts: 108 Comments: 30241
1098. KEEPEROFTHEGATE (Mod)
06L/TD/F/CX
MARK
36N/61W


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


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


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

Member Since: July 15, 2006 Posts: 163 Comments: 52197
How many names does Jason have?!?!? I already have deleated 7!
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long time lurker here.....

anyone have a link for the latest gfs loop
or euro
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Quoting Tazmanian:




you no if you keep posting photos of crows like that on the blog you be earning a 24hr ban i re call last year a few got ban for posting a photo of fish so i would be care full on how many time you post that in a row
kool good looking out
Member Since: July 25, 2010 Posts: 0 Comments: 2473
George Noory is discussing the recent epidemic of red/yellow/orange fireballs seen streaking across the skyLink
Member Since: August 13, 2007 Posts: 0 Comments: 10458
Quoting gugi182:
I've been noticing behind 93L there is a tropical wave coming out of Africa i don't know if you guys have noticed. i don't know if the National Hurricane Center has notice it as well. It looks like the cape Verde Season is picking up speed.

Indeed it want to picking up, BUT whit all the SAL in the area??? :"(
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1091. ncstorm
Quoting wunderstorm87:

They're rotating around the Atlantic ridge. We already saw this happen with Emily. Part or most of the storm was absorbed by the trough while the rest rotated around the ridge and is now 94L.

Henry Margusity wants 94L to be called Emily. I don't think he has much of a case though given that the majority of it was absorbed by the trough.


so if 92L follows the projected path forecasted by the models, it might come back again for a second round?
Member Since: August 19, 2006 Posts: 13 Comments: 13433
Quoting KoritheMan:


They always bring up 2005. Just ignore it.
Kori let me ask you something, The cold front that is supposed to come down south this weekend. Do you see it stalling out in the GOM and developing? Or anyone else can help me out with it.
Member Since: July 25, 2010 Posts: 0 Comments: 2473
1089. Torgen
Quoting BahaHurican:
I think we've all been feeling a kind of "ominosity" [ok, not a word, but still...] to the season.... we've had too many of these storms with one thing that isn't working right....

Makes u feel like u r waiting for the other shoe to drop....


You mean having a storm that isn't afflicted in some way? ;)
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Quoting bigwes6844:
Or you will be eaten crow for dinner! If you are wrong




you no if you keep posting photos of crows like that on the blog you be earning a 24hr ban i re call last year a few got ban for posting a photo of fish so i would be care full on how many time you post that in a row
Member Since: May 21, 2006 Posts: 5089 Comments: 114048
Quoting KoritheMan:


To my knowledge no, though there certainly been several transpacific storms, such as John in 1994:

What a storm.

Just did some research on it. Amazing that it was able to last 31 days and cover 8000 miles.
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93L's shape looks familiar...
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Quoting spathy:
Question
Who did the contest blog before season about the timing and # of storms?
I dont remember my guess.
Hm. Don't remember anybody actually running it this year. Ossgss did it last year...

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Quoting ncstorm:
can someone explain why these are being force back?


They're rotating around the Atlantic ridge. We already saw this happen with Emily. Part or most of the storm was absorbed by the trough while the rest rotated around the ridge and is now 94L.

Henry Margusity wants 94L to be called Emily. I don't think he has much of a case though given that the majority of it was absorbed by the trough.
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Quoting hurricaneben:
Nobody should give up on this season yet. So maybe this doesn't live up to become some catastrophic land-only year like 2005 for example but this is no 2010 either. I have a bad feeling about what's coming up beginning in just a couple of weeks or so.
I think we've all been feeling a kind of "ominosity" [ok, not a word, but still...] to the season.... we've had too many of these storms with one thing that isn't working right....

Makes u feel like u r waiting for the other shoe to drop....
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1082. gugi182
you could still make it 93L
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Quoting TropicalAnalystwx13:

Needs more ketchup.
Lmao
Member Since: July 25, 2010 Posts: 0 Comments: 2473
Quoting TropicalAnalystwx13:


Hey, I've brought up 2005 today!


I don't know the context of that though, as I just logged on. :P
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1078. gugi182
I've been noticing behind 93L there is a tropical wave coming out of Africa i don't know if you guys have noticed. i don't know if the National Hurricane Center has notice it as well. It looks like the cape Verde Season is picking up speed.
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What about Ioke?
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Quoting farhaonhebrew:
Hello, you realize that each system when forecasting affecting Puerto Rico tends to weaken?

That's is sooooo TRUE!!! OmG I think is cause because of the HAARP located on Lajas, PR,(soutwestern corner of the Island) LOL
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Quoting KoritheMan:


They always bring up 2005. Just ignore it.


Hey, I've brought up 2005 today!
Member Since: July 6, 2010 Posts: 108 Comments: 30241
Quoting BahaHurican:
Pple r bringing up the '05 season pretty regular today, but I don't think we're going to be even as active as last year number-wise. Still don't think we'll get to more than 16 or so.


They always bring up 2005. Just ignore it.
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Quoting hurricaneben:
Nobody should give up on this season yet. So maybe this doesn't live up to become some catastrophic land-only year like 2005 for example but this is no 2010 either. I have a bad feeling about what's coming up beginning in just a couple of weeks or so.


11/28 named storms in 2005 were fish storms.

Interesting huh?
Member Since: July 6, 2010 Posts: 108 Comments: 30241
Quoting Tropicsweatherpr:
Levi,do you see the CV season that is upon us having systems classified in the MDR west of 40W instead of having formations In the Eastern Atlantic near the CV islands because of the persistant monsoon trough?



If I may add to your question. It's called the Main Development Region for a reason, most storms develop in this area. Storms developing in the Eastern Atlantic are far and few between and typically find a quick path out to sea. I keep going back to the super active 2005, not a single storm that formed in the Eastern Atlantic effected land. Only Emily that formed in the MDR went on to strike land. All other storms that did not re-curve and hit land formed west of 60W.
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Quoting stormwatcherCI:
Do you think it has a good chance at development ?


Yes. It just needs to sustain any established convection.
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Pple r bringing up the '05 season pretty regular today, but I don't think we're going to be even as active as last year number-wise. Still don't think we'll get to more than 16 or so.
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Quoting stormpetrol:


I said it before and I'll say it again though I could be totally wrong , 93L will probably be the first real deal of the 2011 Season!!


It does have a good chance to. If it can take advantage of its opportunities, then it could be the first real deal.
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Quoting KoritheMan:


Currently, I'm kind of thinking the model consensus may be a bit too far south, as a pronounced weakness is forecast to develop within the western Atlantic in about three or four days, which should be able to impart some poleward pull on this system.

However, the chances of this entering the Caribbean, especially if it doesn't develop, have increased from yesterday.

I have my doubts, however, as to whether or not it will be able to traverse the entirety of the Caribbean like Don did.
Do you think it has a good chance at development ?
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Quoting bigwes6844:

Needs more ketchup.
Member Since: July 6, 2010 Posts: 108 Comments: 30241
Nobody should give up on this season yet. So maybe this doesn't live up to become some catastrophic land-only year like 2005 for example but this is no 2010 either. I have a bad feeling about what's coming up beginning in just a couple of weeks or so.
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Quoting stormwatcherCI:
Kori, what are your thoughts on 93 L ?


Currently, I'm kind of thinking the model consensus may be a bit too far south, as a pronounced weakness is forecast to develop within the western Atlantic ridge in about three or four days, which should be able to impart some poleward pull on this system.

However, the chances of this entering the Caribbean, especially if it doesn't develop in the near-term, have increased from yesterday.

I have my doubts, however, as to whether or not it will be able to traverse the entirety of the Caribbean like Don did.
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.