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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Looking at 94L, 92L, and 93L.. its almost impossible to tell which one might become Gert first they are all really disorganized this morning. Basing this entirely off model support, but I'd stick my neck out slightly for 92L to become Gert then 93L becoming Harvey next week. There's an equally likely chance 92L won't develop and 93L will become Gert and vice versa.
Member Since: July 8, 2005 Posts: 259 Comments: 23856
1659. ackee
Iam trying to figure what going on with 93L shear seem very low DIR air seem to somewhat of a factor but system just seem have even lost its spin think NHC need deactivate 93L for now just my view
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Quoting Landfall2004:


Even to the untrained eye, this speaks volumes. Is that circular pattern off FL how we got Jeanne back after she meandered off in 2004? We called it the Fujiwama!
Jeanne, IIRC, was following a trough out, lost the steering [Nward] and then got pushed west by the re-expanding high. That was one scenario that the models were considering with Emily, may she rest forever....

This situation is a bit different.
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Quoting Tazmanian:
SPECIAL TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM PDT SAT AUG 13 2011

FOR THE EASTERN NORTH PACIFIC...EAST OF 140 DEGREES WEST LONGITUDE..

FIRST VISIBLE SATELLITE IMAGES INDICATE THAT THE LOW PRESSURE SYSTEM
CENTERED ABOUT 1100 MILES SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA HAS BECOME BETTER ORGANIZED...AND A TROPICAL DEPRESSION
COULD BE FORMING. IF THIS DEVELOPING TREND CONTINUES...ADVISORIES
WILL BE INITIATED LATER TODAY. THIS SYSTEM HAS A HIGH CHANCE...70
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES GENERALLY WESTWARD AT AROUND 10 MPH.
Now watch them get a Hurricane to make it 6 straight.
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1656. hydrus
Quoting tropicfreak:








I lived at Twin Palms Marina, About a hundred feet from the Andy Rossi street sign...Went to high school with his grand kids. Looks a liitle different out there these days..
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Quoting ackee:
what will become of 93L

A TS
B TD
C OPen wave
D disscipate


A

Could quite possibly become a hurricane.
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Quoting tropicfreak:


They are warm enough.


Storms have made it out there, though it's not a common thing. I'd think it would be more likely in an el Nino, though.
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Quoting Landfall2004:


So, just how many "ignore" lists am I on? :<(


Not on mine.
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Quoting gugi182:
93L is at 10% can someone explain me why and if there's any chance of it reviving?


You have to remember that 10% only defines the next 48 hours. If you had to affix a percentage for the entire duration of the tropical wave, it'd prob be 50%? The 10% is just the next 48 hours, not forever.
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Quoting Landfall2004:


Even to the untrained eye, this speaks volumes. Is that circular pattern off FL how we got Jeanne back after she meandered off in 2004? We called it the Fujiwama!


Hey there, don't have anyone on ignore...lol...I was hoping one of the experts would answer....I'm just not qualified :}
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1650. PGIgirl
I can't believe I almost forgot Charlie. 7 years ago today the eye of that guy passed directly over my house in PGI. Took landscaping, pool cage, roof tiles and a strip of gutter, but left the house intact and dry. Wisely we had "got the he__ out"! Thank you State of Florida for the "post-Andrew" building codes! Anything built after those were enforced pretty much held together when the winds were clocked at 145 knots at the airport just east of our house. Please no major landfalls anywhere this year.
Member Since: Posts: Comments:
SPECIAL TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM PDT SAT AUG 13 2011

FOR THE EASTERN NORTH PACIFIC...EAST OF 140 DEGREES WEST LONGITUDE..

FIRST VISIBLE SATELLITE IMAGES INDICATE THAT THE LOW PRESSURE SYSTEM
CENTERED ABOUT 1100 MILES SOUTHWEST OF THE SOUTHERN TIP OF BAJA
CALIFORNIA HAS BECOME BETTER ORGANIZED...AND A TROPICAL DEPRESSION
COULD BE FORMING. IF THIS DEVELOPING TREND CONTINUES...ADVISORIES
WILL BE INITIATED LATER TODAY. THIS SYSTEM HAS A HIGH CHANCE...70
PERCENT...OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS
AS IT MOVES GENERALLY WESTWARD AT AROUND 10 MPH.
Member Since: May 21, 2006 Posts: 5091 Comments: 114914
Quoting Landfall2004:


So, just how many "ignore" lists am I on? :<(
Well, I just got on, so I know ur not on mine... lol going back now to read earlier posts, but if u r talking abt 92L and 94L, I'm watching these two with great interest...
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TD 6E might form soon according to the Special TWO a few minutes ago
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1646. ackee
what will become of 93L

A TS
B TD
C OPen wave
D disscipate
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Quoting OracleDeAtlantis:
It's pretty clear that 92L is outpacing 94L at this point, and will contribute a nice shot of moisture into the mix of these two. It could get interesting if both deepen with the combined moisture.

I'm expecting 94L to continue slowing down, due to the lower pressure exerted by 92L's wave, but by how much I'm not sure. I can say one thing, this type of interaction is virtually impossible for the models to accurately predict.

If they were to combine, even as wave of low pressure, they could in theory, begin to weaken one another at first, pushing them both further west than anticipated now, because they would essentially become one giant wave of low pressure. Might even become some kind of superwave moving West.

This will be the most interesting interaction so far this season between two adjacent systems, I believe. We all may get an education in the Fujiwara effect.
"Some level" is correct ....

How about one giant tropical wave moving west into the GOM?

So far, so good ... except I don't think they're going to the GOM.

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1644. ackee
seem 94L 92L might devlop further the RACE on how will become GERT first
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Quoting GTcooliebai:
You know what now that you mention it Bonnie brought more winds to our area as it moved north of us and made landfall along the Big Bend Area. I stayed put and decided to ride out Charley the day before it hit I remember in school everyone had their eyes glued to the t.v. and my last class was band & the teacher had us put all the instruments in the middle of the room. The morning before the storm was suppose to hit, I heard sirens going off outside as I was walking over to my Grandma's, when I returned home about an hr. later I turned on the news & Tampa's mayor Pam Iorio was talking & at that same moment the person conducting the interview got word from one of the local met. that Charley had begun its right hand turn well before it was expected.
lucky for you not for us Charley's turn brought extensive damage here in Port Charlotte but that damage would have been Much worse is Tampa
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1642. txjac
Quoting DFWjc:
It's been nice with two out of last three days of rain, the 100 consecutive streak over, I'm am soooo thankful for the cooler weather here in North Texas!!


Quit keeping it all to yourself!! Send some to Houston please! lol
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Quoting stillwaiting:
i can remember sarasota area beingbin lockdown mode,we ewaited and charlry never came,lucky for us ,could you imagine what he would have done to srq???,i "rode out" charley at a friends house at benneva and bee rdige area,and as you stated not a gust over 30mph and maybe .50 inches,as a matter of fact the feeder band that came thru the night prior was much strongervwith 50mph winds and about a inch an about 45min


Yeah I think we came as close to a category4 as a person can get without seeing any damage. It's only going to make people shrug off the next storm that comes our way. We call it the "Sarasota bubble"
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Morning everybody. I guess they upgraded to Franklin this a.m.? Wasn't nothing on the NHC site at ll p.m......

Also saw the "good" news re 93L.... though this could be bad news if it means we get a definite Caribbean tracker out of it...

Taking it easy today...
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1638. HCW
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1637. DFWjc
It's been nice with two out of last three days of rain, the 100 consecutive streak over, I'm am soooo thankful for the cooler weather here in North Texas!!
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Quoting Landfall2004:


Even to the untrained eye, this speaks volumes. Is that circular pattern off FL how we got Jeanne back after she meandered off in 2004? We called it the Fujiwama!


So, just how many "ignore" lists am I on? :<(
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1635. 900MB
Quoting tropicfreak:


I see it too.



Looks like a wave for now, but it's weather, anything can happen.
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Quoting stillwaiting:
i can remember sarasota area beingbin lockdown mode,we ewaited and charlry never came,lucky for us ,could you imagine what he would have done to srq???,i "rode out" charley at a friends house at benneva and bee rdige area,and as you stated not a gust over 30mph and maybe .50 inches,as a matter of fact the feeder band that came thru the night prior was much strongervwith 50mph winds and about a inch an about 45min
You know what now that you mention it Bonnie brought more winds to our area as it moved north of us and made landfall along the Big Bend Area. I stayed put and decided to ride out Charley the day before it hit I remember in school everyone had their eyes glued to the t.v. and my last class was band & the teacher had us put all the instruments in the middle of the room. The morning before the storm was suppose to hit, I heard sirens going off outside as I was walking over to my Grandma's, when I returned home about an hr. later I turned on the news & Tampa's mayor Pam Iorio was talking & at that same moment the person conducting the interview got word from one of the local met. that Charley had begun its right hand turn well before it was expected.
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Quoting WeatherNerdPR:
Eww, 94L is naked...

Hey 94L! (sarcastically) Nice outfit dude! pfff bwahahaha!!!!
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Quoting gugi182:
93L is at 10% can someone explain me why and if there's any chance of it reviving?


It's looking anemic now, but it'll probably revive as it approaches the Caribbean.
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Quoting gugi182:
93L is at 10% can someone explain me why and if there's any chance of it reviving?


It is lacking a lot of convection, and it will likely revive.
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1630. gugi182
93L is at 10% can someone explain me why and if there's any chance of it reviving?
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Quoting EYEStoSEA:


Even to the untrained eye, this speaks volumes. Is that circular pattern off FL how we got Jeanne back after she meandered off in 2004? We called it the Fujiwama!
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Quoting WeatherfanPR:
Possible Low developing ?

Link


WxLogic pointed that out a couple of hours ago.... looks like it broke off of 94L and jogged SW... some of the models pick it up... in fact... I vaguely remember one on Wed. or Thurs. that showed it.
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Quoting EYEStoSEA:


Looking at that it looks like it may brush the Canadian Maritimes.
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Quoting WeatherfanPR:
Possible Low developing ?

The NAM in its recent runs really wants to develop that area and move it towards the Bahamas, something to keep an eye on.
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Quoting Klolly23:


That image is wild. I live in northwestern Sarasota county only 30 mins from where the eye of Charley made landfall and the highest winds we had didn't even top 30mph
i can remember sarasota area beingbin lockdown mode,we ewaited and charlry never came,lucky for us ,could you imagine what he would have done to srq???,i "rode out" charley at a friends house at benneva and bee rdige area,and as you stated not a gust over 30mph and maybe .50 inches,as a matter of fact the feeder band that came thru the night prior was much strongervwith 50mph winds and about a inch an about 45min
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Eww, 94L is naked...
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1621. msphar
don't count on it, its a graveyard for storms
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Possible Low developing ?

Link


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...FRANKLIN STRENGTHENS SLIGHTLY OVER THE NORTH ATLANTIC BUT REMAINS NO THREAT TO LAND...
11:00 AM EDT Sat Aug 13
Location: 39.0°N 57.9°W
Max sustained: 45 mph
Moving: ENE at 22 mph
Min pressure: 1004 mb
Member Since: July 8, 2005 Posts: 259 Comments: 23856
Quoting msphar:
98E will never make it to Hawaii. the water is too cold out there.


They are warm enough.


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Quoting WeatherfanPR:
something is trying to develop near 23n and 63w and moving wsw !!!


I see it too.

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weatherfan, what and where. can you post a map
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1615. msphar
98E will never make it to Hawaii. the water is too cold out there.
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1614. rod2635
Water vapor loop still showing a lot of dry air out there between the Antilles and CV. Current crop of invests may end up being sacrificial moisture lambs to allow the next series a reasonable chance of development.
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something is trying to develop near 23n and 63w and moving wsw !!!
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1612. ncstorm
The NE/Midatlantic is looking at some type of storm up there next week
day 5 Seas level Pressures and Fronts

Day6

Day7
another Frontal boundary off the east coast and 93L affecting the Islands
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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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