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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1311. FlaLily
Anybody comment on this....
http://www.meteorological-lies.com/Emily2.html
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Quoting SherwoodSpirit:


Danke. :)

By the way, I stole that African image from this site.
Link

It's one of my favorites.


Adding it to my collection...

Want a bunch of them I use? Check this link and use the ones that have anim in it...

Link
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Quoting nofailsafe:


Unless it's a repeat of Allison (2001).


It came back around to us on a Friday, trash day for the neighborhood where we were trying to sell our old house. I got a call later that night that our trash cans, which were sitting on our curb, had floated down the street and into the bayou. He said he tried to catch them - but they were just moving too fast. Luckily no damage to either of the houses - we were luckier than a lot of people.
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1308. JLPR2
This is going to sound ridiculous but the Xtrap is basically the consensus. xD
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Das repost
Member Since: June 9, 2007 Posts: 4 Comments: 15864
1306. Seawall
Different models views for 93L
Image and video hosting by TinyPic
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1305. JLPR2
Impressive how the models have shifted since 93L was designated.
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Quoting sunlinepr:


Excellent post...


Danke. :)

By the way, I stole that African image from this site.
Link

It's one of my favorites.
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Quoting OracleDeAtlantis:



Geeze, I'm quoting myself now. I guess it's time for bed.

Bring me my meds!

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Quoting SherwoodSpirit:
Ok, lessee if I understand where everything is right now...
I think I got everything right here, except maybe ex-Emily because I haven't watched to see where her remains went.



Don't forget about that AOI off NC. Did I wake presslord?
Member Since: September 2, 2006 Posts: 110 Comments: 6874
Quoting SherwoodSpirit:
Ok, lessee if I understand where everything is right now...
I think I got everything right here, except maybe ex-Emily because I haven't watched to see where her remains went.



Excellent post...
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Quoting OracleDeAtlantis:
Emily split into two parts. Half became 94L, and the other half is what you're looking at, I think.

I don't know what half went in what direction, however. I'm not sure if the mid to upper level vorticity went northeast, and the surface went south, then southwest. Someone with more experience than I, can probably come up with some better imagery, showing this.

94L is half of Emily, I do know that.

The Wicked Witch of the East is still alive, but the ruby slippers may be missing, we'll have to wait and see.


Geeze, I'm quoting myself now. I guess it's time for bed.
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1299. j2008
Quoting tropicfreak:
j2008 that track has Ivan written all over it.

Sure is an unsettleing thought isnt it? Lets hope for the best out of it.
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Quoting nofailsafe:


Unless it's a repeat of Allison (2001).
Oh no!!!! not that. Keep the storms moving! Not stall!
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Quoting rv1pop:
OK. I saw a link that looked good to use with my old, slow computer. I have found that WU will sometimes double post, if I do not wait the 5 minutes after I post for WU to update before trying to go on to something else (IE. even another website). It appears you have a faster computer and would not see this.

It happens to me quite often... I post something and if I try to fix or correct it, when I re Post, it duplicates...

That's what happened... I tried to fix the new duplicated post... with that tool for saving animations... and the guy reports me....

So the best win win situation, is to ignore me...
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Quoting sunlinepr:


Thanks...TT....
I'm feel very relaxed....... He did put me on ignore... ;-)

alright cool.

How's life going in Puerto Rico?
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Quoting SherwoodSpirit:
Ok, lessee if I understand where everything is right now...
I think I got everything right here, except maybe ex-Emily because I haven't watched to see where her remains went.

Emily split into two parts. Half became 94L, and the other half is what you're looking at, I think.

I don't know what half went in what direction, however. I'm not sure if the mid to upper level vorticity went northeast, and the surface went south, then southwest. Someone with more experience than I, can probably come up with some better imagery, showing this.

94L is half of Emily, I do know that.
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Quoting SherwoodSpirit:
Ok, lessee if I understand where everything is right now...
I think I got everything right here, except maybe ex-Emily because I haven't watched to see where her remains went.



All abooooard~~!
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j2008 that track has Ivan written all over it.
Member Since: September 2, 2006 Posts: 110 Comments: 6874
Quoting MississippiWx:


Lol...It's all good. We are pretty gun-shy when it comes to hurricanes along the Central Gulf Coast since we had a pretty rough go of it 2008 and before...Just know that we have no threat at all for now.
kool with me
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Ok, lessee if I understand where everything is right now...
I think I got everything right here, except maybe ex-Emily because I haven't watched to see where her remains went.

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Quoting Thundercloud01221991:


he removed it after I posted.... he had just linked to a site and 3 posts later linked to it again... and no I am not a troll

I removed the post... I am sorry I understand typos... I just am fed up with the troll action here so I overreacted.
Sunlinepr is definitely not a troll.

Check join dates and post counts when wondering if someone is a troll. The later the date and the lower the number, the more likely its a troll. Usernames/handles can be a dead give away sometimes as well.
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Quoting bigwes6844:
Mississippi U know me i get real nervous if something does try to make it into the GOM. Just look at the water temps. But i understand what u mean by that though


Lol...It's all good. We are pretty gun-shy when it comes to hurricanes along the Central Gulf Coast since we had a pretty rough go of it 2008 and before...Just know that we have no threat at all for now.
Member Since: July 15, 2006 Posts: 17 Comments: 10189
Quoting bigwes6844:
now i know we are but forget that give me a T.S. before a darn Hurricane


Unless it's a repeat of Allison (2001).
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Quoting tropicfreak:


Well maybe not. The US is wayyy overdue
now i know we are but forget that give me a T.S. before a darn Hurricane
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1286. j2008
Quoting tropicfreak:


Through the yucatan and cuban passage.

Spells nothing but trouble.

Its a very bad time of year to have a cyclone in the Caribbean, and Gulf. Its gonna get scary if 93 desides to wonder in.
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Quoting MississippiWx:


Lol...You take these model runs too seriously.

1. Anything beyond the Eastern Caribbean should be discounted since it is so far out in time.

2. 93L's development chances are iffy for now. If we actually get a developed tropical cyclone, then we can start trying to nail down track.
Mississippi U know me i get real nervous if something does try to make it into the GOM. Just look at the water temps. But i understand what u mean by that though
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Quoting MississippiWx:
Pointless to post, but at 228 headed back WNW as the trof lifted out quickly..



Through the yucatan and cuban passage.

Spells nothing but trouble.
Member Since: September 2, 2006 Posts: 110 Comments: 6874
Quoting MississippiWx:
Makes landfall in South Texas at the end of the run. Lol. End of the run is just for humor:



If it does make a Texas landfall I think a lot of that is going to depend on the position and strength of the ridge we've got sitting on us. If it retains its strength it seems like a Mexico or S. Texas landfall would be likely were it to make it that far. Northwest gulf coast not so likely unless the ridge backs off.
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1282. rv1pop
Quoting Thundercloud01221991:


he removed it after I posted.... he had just linked to a site and 3 posts later linked to it again... and no I am not a troll
OK. I saw a link that looked good to use with my old, slow computer. I have found that WU will sometimes double post, if I do not wait the 5 minutes after I post for WU to update before trying to go on to something else (IE. even another website). It appears you have a faster computer and would not see this.
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Makes landfall in South Texas at the end of the run. Lol. End of the run is just for humor:

Member Since: July 15, 2006 Posts: 17 Comments: 10189
Quoting bigwes6844:
so maybe a mexico landfall hopefully


Well maybe not. The US is wayyy overdue
Member Since: September 2, 2006 Posts: 110 Comments: 6874
1279. pottery
Quoting JLPR2:
Seems the GFS thinks 93L is one of those systems that just doesn't strengthen with nice TCHP and windshear, the only thing that I think could actually be a problem is SAL.

Very little SAL west of 93.
The problem that it has/will have in the future is dry air.
Not a lot of moisture west of it.
Look at the Mid-Level WV.
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Quoting TomTaylor:
calm down sunline.

Just some guy over reacting


Thanks...TT....
I'm feel very relaxed....... He did put me on ignore... ;-)

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Quoting bigwes6844:
Mississippi please tell me this is a joke. That look like a gustav type of path it may do. WOW i hope thats not right or well be in deep trouble here on the Gulf Coast


Lol...You take these model runs too seriously.

1. Anything beyond the Eastern Caribbean should be discounted since it is so far out in time.

2. 93L's development chances are iffy for now. If we actually get a developed tropical cyclone, then we can start trying to nail down track.
Member Since: July 15, 2006 Posts: 17 Comments: 10189
Quoting JLPR2:
Seems the GFS thinks 93L is one of those systems that just doesn't strengthen with nice TCHP and windshear, the only thing that I think could actually be a problem is SAL.




If you watch the SAL loop, you'll see that it flares back up towards the end. Interestingly, the 'great red spot' off the coast of Florida seems to be softening up a bit. There's not a lot further west though, as would be expected.

SAL Movie (CIMSS)
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Quoting MississippiWx:
Pointless to post, but at 228 headed back WNW as the trof lifted out quickly..

Mississippi please tell me this is a joke. That look like a gustav type of path it may do. WOW i hope thats not right or well be in deep trouble here on the Gulf Coast
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1274. JLPR2
Seems the GFS thinks 93L is one of those systems that just doesn't strengthen with nice TCHP and windshear, the only thing that I think could actually be a problem is SAL.
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Quoting rv1pop:
Are you for real? The blog is so slow or I would not respond. With the number of comments you should not be a troll, but who knows. I saw nothing posted that was out of line. What gives?



he removed it after I posted.... he had just linked to a site and 3 posts later linked to it again... and no I am not a troll

I removed the post... I am sorry I understand typos... I just am fed up with the troll action here so I overreacted.
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Quoting sunlinepr:


Man, Please, I beg you... put me on ignore...

It was a typo.... But remember... put me on ignore...
calm down sunline.

Just some guy over reacting
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Quoting MississippiWx:
192...Headed north, feeling the weakness from the big trof to the north...

oh boy... just hope it doesn't go into Gulf of Mexico.
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1270. ackee
I think the GFS track seem possble the longer 93L takes the more south and west it tracks we be keeping a close eye on 93L IN JAMAICA DEAN the past close by round about the same time
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Pointless to post, but at 228 headed back WNW as the trof lifted out quickly..

Member Since: July 15, 2006 Posts: 17 Comments: 10189
Quoting nofailsafe:


If it does cross the Yucatan by that point it might not have a lot of strength, ideally if it were to do that it would either dissipate quickly over land or over the GOM (The latter option doesn't sound too likely.) Once it interacts with land though, you've got something that is somewhat less certain. If it sustains itself then regardless of where it ends up afterwards, it's got a lot of nice toasty gulf waters to pass over.
yeah thats wat fears me the most is that we may see a horrible storm in the GOM and eat up that water that may increase it. I hope it does interfer with land. That track that the GFS has it going to a dangerous path.
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1267. rv1pop
Are you for real? The blog is so slow or I would not respond. With the number of comments you should not be a troll, but who knows. I saw nothing posted that was out of line. What gives?

Quoting Thundercloud01221991:


you already posted this... if you post it again I will have to report you
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192...Headed north, feeling the weakness from the big trof to the north...

Member Since: July 15, 2006 Posts: 17 Comments: 10189
93L will not be hitting mexico in this run
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Quoting Seawall:
The Global IR, what goes around, comes around.
Link


I love that visual...it just fascinates me how everything works to and from....:)
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Quoting bigwes6844:
so maybe a mexico landfall hopefully


If it does cross the Yucatan by that point it might not have a lot of strength, ideally if it were to do that it would either dissipate quickly over land or over the GOM (The latter option doesn't sound too likely.) Once it interacts with land though, you've got something that is somewhat less certain. If it sustains itself then regardless of where it ends up afterwards, it's got a lot of nice toasty gulf waters to pass over.
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Quoting j2008:

They dont do an update at 4am but I think they might do a special advisory if thats what your refering to.
On a GOM situation on 93L I think it cant be ruled out. I think we all need to keep our eyes on it, could be pretty bad.
oh okay i thought they do 6 hrs every update but it will be very scarry because the GOM is really warm as hell!!! Haven't had a real storm to get here since DON
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Quoting MississippiWx:
156:



Models will keep updating and taking in consideration if the system stays as a wave or if it turns into a TS...
The weaker, the farthest it will go West...
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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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