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 KEEPEROFTHEGATE:
maybe but it removes the troll


Indeed...with great alacrity, I would suspect...LOL

Could we move him away from the infrastructure a bit before detonation, do you suppose?
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Quoting troy1993:
God I wish I can get a group together and just smash the heck of that Texas ridge..anyone else with me?


Well, there's always Angry Birds.

Mayber they can smash through that ridge...
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Quoting MississippiWx:
GFS has basically dropped any development of 93L. That's an extreme change from what it has been showing.


GFS is trash at this point. Every run has a different dramatic solution.
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Quoting MississippiWx:
GFS has basically dropped any development of 93L. That's an extreme change from what it has been showing.


And extreme flip flops are not to be trusted. This run may be overplaying the current shear which stretches to nearly 40W.

The best advice is to watch and wait.
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Quoting Floodman:


LOL...I've always been partial to bombastic, among other words


He's on You Tube and chases "clear-air mode" radar echoes.

Really funny stuff.
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Quoting Stormchaser2007:
It seems it's becoming less likely that 93L will become a cyclone before moving through the Windward islands.

95L may become a tropical depression or storm tonight or tomorrow.



In fact, it almost looks like 95L is becoming the best looking storm of the season so far. And it is not even named.
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Good morning.

Blog update:

Tropical Tidbit for Friday, August 12th, with Video
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153. JRRP



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12z GFS throws 93L into the BOC as a weak wave which is later absorbed by a developing EPAC storm.

The GFS was 93L's number one fan. Not good to loose it for development.
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Quoting Floodman:


Yes, I have found that the efficacious use of the word judicious can be shrewd or even perspicacious...LOL

I love English! So many ways to repeat oneself


Will have to google this to help me decide whether I should put you on ignore for offensive language.
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Quoting CitikatzSouthFL:

94 is the wicked spawn of Emily. Guess it just wants to go back and check out mama's vacation spot in the Carib!


if 94 develops we shall call it EMILINA...
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Quoting PrivateIdaho:


I just like saying HFAARP.


LOL...I've always been partial to bombastic, among other words
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I keep the gin in the freezer to help conserve ice.
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Quoting CorneliaMarie:
I just like saying HFAARP.

yeah, and Grothar likes AARP....



That is because Grothar does not have a lisp.
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GFS has basically dropped any development of 93L. That's an extreme change from what it has been showing.
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Quoting Floodman:


Yes, I have found that the efficacious use of the word judicious can be shrewd or even perspicacious...LOL

I love English! So many ways to repeat oneself


You can say that again ! ( pun intended )
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92L looks better today

93L needs some help

94L not sure what too say


95L is on its way too a TD or TS
Member Since: May 21, 2006 Posts: 5091 Comments: 114956
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Quoting TampaTom:


My money is on it growing in size, developing scales and hot atomic breath and menacing downtown Tokyo.



I miss the original Godzilla.
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Quoting BahaHurican:
Hence the judicious use of the word judicious....


Yes, I have found that the efficacious use of the word judicious can be shrewd or even perspicacious...LOL

I love English! So many ways to repeat oneself
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Quoting Tampatom:
Eat some peanuts and drink some beer before it happens. It will help you recover from the effects...



Me thinks a Babel fish will help the 850mb vorticity discussion !!!

I'm watching 95L as I will be on the Irish Atlantic coast next week
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What about off the coast of Alabama and Florida does that look like anything that may form into something. I sure hope not.
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Quoting tiggeriffic:


I have CDO...it is like OCD but the letters are in alphabetical order just as they should be.... :)


+10
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Quoting WhoDat1:
(Melting Ice) ..omg.. Soon they'll be trying to get us 2 donate 2 polor bear rescues,,
So much going on in the atlantic,,,why mension ice,,,back to the important stuff..
we are already beginning to see the effects and these effects shall become more intense and destructive with the passage of time and total disappeance of the ice this is a big deal even if you refuse to see it watch wait see faster and faster for you and me
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Quoting Floodman:


Towel...where on earth (or off of it) did I put that blasted towel


Don't forget to put the Babel fish in your ear.
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Quoting Floodman:


Because the loss of ice effects EVERYTHING


EXACTLY...loss of ice means warmer waters EVERYWHERE, warmer waters means storms have a larger basin for development during times when they normally would not, also means that if the waters are warmer then multiple storms in a row would have a greater chance of not fizzling out because it would take longer for the cold water to churn up...ICE MELTING IS A DOMINO EFFECT
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Quoting iamajeepmom:


Yup, thats what ALL the news stations are saying here ... Kansas has tornadoes so I'd be more concerned with that :) And just WHERE did 94 come from?

94 is the wicked spawn of Emily. Guess it just wants to go back and check out mama's vacation spot in the Carib!
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Quoting Stormchaser2007:
It seems it's becoming less likely that 93L will become a cyclone before moving through the Windward islands.

95L may become a tropical depression or storm tonight or tomorrow.



Yeah, with the loss of organization in 93L, the GFS has been less aggressive with it. Things can change right back, though. 93L should have a fairly decent environment ahead of it and should still be watched closely.
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Here is a handy reference guide to convert mbs to feet above sea level. Vorticity at the 850 mb level does not necessarily mean that a system has a surface low. Many systems have been known to have very vigorous 850 mb circulations but little or nothing at the surface. Very often, we see the vort at 850 mbs works its way down to becoming a closed low at the surface.
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now theres a response for ya!

LOL
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Quoting KEEPEROFTHEGATE:


Tsar Bomba... now that's global warming!
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Quoting TampaTom:


Not according to Ford Prefect.


Towel...where on earth (or off of it) did I put that blasted towel
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Flood my friend things are doing well up here,although it looks like our summer is done.We have cooled down drasticly and turned very rainy around 5 inches already this month. Oops,I guess I shouldn't mention the subject or rain around Texans should I?
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Quoting Floodman:


Oh my, a 100 megaton device? That's, well, a bit excessive possibly...
maybe but it removes the troll
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thanks!
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Quoting Squid28:


A note of caution, if you over indulge in the prescribed treatment, especially the hops based brews, you may further exacerbate the very side effects you were originally trying to mitigate......
Hence the judicious use of the word judicious....
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Quoting WhoDat1:
(Melting Ice) ..omg.. Soon they'll be trying to get us 2 donate 2 polor bear rescues,,
So much going on in the atlantic,,,why mension ice,,,back to the important stuff..


Because the loss of ice effects EVERYTHING
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Quoting Squid28:


A not of caution, if you over indulge in the prescribed treatment, especially the hops based brews, you may further excerbate the very very side effects you were originally trying to mitigate......


Not according to Ford Prefect.
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way too many pictures.
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It seems it's becoming less likely that 93L will become a cyclone before moving through the Windward islands.

95L may become a tropical depression or storm tonight or tomorrow.

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Quoting NEwxguy:
79.HOTWHEELS99
You been saying this over and over and over and over all morning.And you wonder why people ignore you,we get your point!!! ****POOF****


My old buddy NEwx! How are things in your neck of these woods?
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Quoting Floodman:


I've heard that...HAARP temporal displacement side effects can be obviated via the judicious use of dry roasted legumes and hops based brewed beverages...


A note of caution, if you over indulge in the prescribed treatment, especially the hops based brews, you may further exacerbate the very side effects you were originally trying to mitigate......
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Quoting KEEPEROFTHEGATE:




Oh my, a 100 megaton device? That's, well, a bit excessive possibly...
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Quoting Floodman:



juuuuust a touch of OCD...LOL


I just like saying HFAARP.
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Hey guys! I know this is a bit much on the pictures, but these are pictures of the heavy storms earlier this week and the flooding it caused! We've gotten this many times this rainy season now but I decided to post pics of the mos recent stuff. The last picture is me standing in the flood waters right in front of my yard! The yard that is mine is the one that has the mail box and the vehicle on the left.
Member Since: August 21, 2008 Posts: 0 Comments: 7400
Quoting Vincent4989:
What to do with Hotwheels:
1.
2.
3. Ignore User


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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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