One third of Arctic ice cap now missing; Midwestern floods; tropical update

By: Dr. Jeff Masters , 12:46 PM GMT on August 24, 2007

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Sea ice in the Arctic continues its record decline, thanks to unusually cloud-free conditions and above-average temperatures. For August 21, the National Snow and Ice Data Center estimated that fully one third of the Arctic ice cap was missing, compared to the average levels observed on that date from 1979-2000. Sea ice extent was 4.92 million square kilometers on August 21, and the 1979-2000 average for the date was about 7.3 million square kilometers. Arctic sea ice has fallen below the record low absolute minimum of 4.92 million square kilometers set in 2005 by about 8%, with another 3-5 weeks of the melting season still remaining. Reliable records of sea ice coverage go back to 1979.


Figure 1. Extent of the polar sea ice on August 21, compared to the average for the date from the 1979-2000 period (pink line). Image credit: National Snow and Ice Data Center.

With one third of the Arctic ice cap already gone, and another month of melting to go, we need to consider what effect this will have on weather, climate, and sea level rise. Well, we don't need to worry about sea level rise, since the polar sea ice is already in the ocean, and won't appreciably change sea level when it melts. However, the remarkable melting of the ice cap will likely lead to unusual weather patterns this fall and winter. The lack of sea ice will put much more heat and moisture into the polar atmosphere, affecting the path of the jet stream and the resultant storm tracks. Expect a much-delayed arrival of winter to the Northern Hemisphere again this year, which may lead to further accelerated melting of the ice cap in future years.

Last week, I remarked that the most recent images from the North Pole webcam show plenty of melt water and rainy conditions near the Pole. It turns out that was misleading, since the webcam is on a ship that was headed towards the pole, but had not reached it. There have been rainy conditions at the Pole this summer, and there is some open water there, but this is not uncommon in summer. Shifting ice frequently opens up leads (cracks) with open sea water at the Pole. It was one of these open leads that British swimmer Lewis Gordon Pugh swam in for 18 minutes this July to draw attention to global climate change.


Figure 2. Total rainfall from August 10-22 as estimated by NASA's TRMM satellite.

Midwest flooding
To get an idea of the magnitude of the flooding that has hit the Midwestern U.S. during the past ten days, take a look at the total amount of rain from August 10-22 (Figure 2). We can blame Tropical Storm Erin for the rain in Texas and Oklahoma (up to 11 inches), and for the nine flooding deaths that occurred in those states. However, the unbelievable rain amounts in excess of 20 inches in Minnesota and Wisconsin were primarily due to a frontal system--with the help of some copious moisture pumped northwards by the counter-clockwise circulation around Erin while it spun over Oklahoma.

Tropical update
There are no threat areas in the Atlantic to discuss. Two of our four reliable forecast models, the NOGAPS and ECMWF, are predicting that a tropical depression could form off the coast of Nicaragua on Sunday. The models forecast that this system would move inland over Nicaragua and Honduras by Monday.

I'll have an update on Saturday morning.
Jeff Masters

After Hurricane Dean (sprinter)
Bulldozer trying to clear sand and debris from Norman Manley Highway(Airport Road)
After Hurricane Dean
Findlay Ohio flood (prairieview)
The flood is over, now the cleanup
Findlay Ohio flood

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797. HopquickSteve
1:34 PM GMT on August 25, 2007
I keep looking at the dr.'s ice cap image and something popped into my head. Is Asian (China/Russia/etc.) CO2 emissions much higher than Canada/USA or Europe's? Because the receding is heavily on the asian side and much less on the Euro-American side.

Reasons why one side melts faster?
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795. aardan
1:30 PM GMT on August 25, 2007
Tropicnerd:

The poles experience full light and full dark each year.

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794. Tropicnerd13
1:29 PM GMT on August 25, 2007
would anyone agree? please reply to my super long comment about the shift in light patterns. i think that may be another reason why the north pole's ice is melting.
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793. StormJunkie
1:31 PM GMT on August 25, 2007
What's up thel? Good to see ya!

I thought it was the SC State Bulldogs?

Just spotty rain sg03!

Morning SW, thanks for the update!

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792. extreme236
1:22 PM GMT on August 25, 2007
well that "blob" has become better organized. wouldnt be surprised to see an invest if it keeps going.
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791. thelmores
1:07 PM GMT on August 25, 2007
mornin ya'll......

things are unusually quiet in the tropics..... see we are back to "blob" watchin at 50W.....

Hey SJ..... you ready for the Rajun Cajuns next week? If we can get some improved O-line play, we may have a nice year! :)
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790. extreme236
1:20 PM GMT on August 25, 2007
so StormW you think there is potential for some brief development with that low pressure off the east coast?
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789. extreme236
1:14 PM GMT on August 25, 2007
another good synopsis StormW!
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788. Tropicnerd13
1:10 PM GMT on August 25, 2007
hello everyone. i know dr. masters is correct on his infromation, and i know he is a very knowledgable person, and this doesn't go against him, but when i was learning about the solar system and weather in school, i recall learning about a shift in the light patterns, where the north pole gets darkness for about 40 years and the south pole gets light for about 40 years. right now the north pole is in the stage of light, and has been for a while now, and sinse records that are accurate are only from 1979 to present time, wouldn't that mean that the last stage of light for the north pole wasn't accurately doccumented, therefor leaving us uncertain if this is the worst the ice has been? there is no doubt in my mind that it is, but i just was wondering if this could just be normal because of straight sunlight for 40 years.
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786. Weather456
1:01 PM GMT on August 25, 2007
As of 1200 UTC the TUTT northeast of the Leeward Islands is forecast to weaken resulting in:

current - less than 10 knots
12 hrs forecast - less than 10 knots
24 hrs forecast - less than 10 knots
36 hrs forecast - less than 20 knots

These forecast correspond to the enviroment the wave is expected to be...not just for the central atlantic.
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785. sporteguy03
1:06 PM GMT on August 25, 2007
Hi StormJunkie,
Any rain in SC to beat the heat? FL got pounded last night 3 inches of rain at Disney and great lightning show.
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784. Weather456
12:57 PM GMT on August 25, 2007
Neither the mm5fsu45a model
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783. StormJunkie
12:57 PM GMT on August 25, 2007
Thanks 456, so if anything were to come of it it would be a model fighter.

What about the shear?
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782. Weather456
12:55 PM GMT on August 25, 2007
The models, NOAGAPS, CMC, GFS and UKM seem not develop anything out of this system (central atlantic wave)
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781. StormJunkie
12:49 PM GMT on August 25, 2007
Morning y'all ☺

Well I see there is still a little interest in the 50w area. Any models showing anything for it?
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780. Coyote2007
12:35 PM GMT on August 25, 2007
I was thinking, maybe this arctic melting means my old history teachers were wrong. They always used to tell us that the European explorers searched in vain, following stories of a "Northwest Passage" that turned out not to be true.

Maybe they WERE true. Before the explorers came.
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779. Dakster
12:31 PM GMT on August 25, 2007
Looks like a nice extra-tropical storm...
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778. Weather456
12:27 PM GMT on August 25, 2007
Animation looks even better
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777. Weather456
12:22 PM GMT on August 25, 2007
I'll have an update later this morning on 3 areas of interest, a broad area of low pressure in the BOC, disturbed weather south of Costa Rico and a tropical wave in the Central Atlnatic
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776. Weather456
12:24 PM GMT on August 25, 2007
Here's a smaller pic from 1215 UTC

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774. kmanislander
12:15 PM GMT on August 25, 2007
This is from the buoy in the BOC
The pressure now is relatively low at 1010.8 approx.
The other interesting thing is you can see how the pressure bottomed out from Dean and at the same time the winds were up significantly.
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773. kmanislander
12:11 PM GMT on August 25, 2007
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772. kmanislander
12:08 PM GMT on August 25, 2007
One final item of interest. The 850 mb vorticity map is showing a fair amount of turning right where the blow up is in the BOC

Something else perhaps to keep an eye on ?

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771. Weather456
10:52 AM GMT on August 25, 2007
Picture of the Day



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770. kmanislander
12:04 PM GMT on August 25, 2007
I am out for now but will check in later.
StormW, something new for you to follow now LOL
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769. extreme236
12:03 PM GMT on August 25, 2007
A lot can happen in 97 days Ike lol. Not even at the peak yet. And if la nina does in fact take hold, then it will be a active late season
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768. extreme236
12:01 PM GMT on August 25, 2007
thanks StormW for the link, interesting info. So, what is your take on the disturbance?
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767. IKE
7:00 AM CDT on August 25, 2007
Tropical weather outlook for planet earth....

"Tropical cyclone formation is not expected during the next 48 hours.".....

97 days left in the Atlantic season.
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766. extreme236
11:59 AM GMT on August 25, 2007
Posted By: kmanislander at 11:55 AM GMT on August 25, 2007.

Hi Extreme

They can develop in the ITCZ but the further S the harder it is for them to develop


Thanks for the answer. I figured they could but I knew it is hard for systems to develop the farther south they are
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765. kmanislander
11:59 AM GMT on August 25, 2007
Ivan was first classified as a depression at 9.7N 27.6W

The disturbance near 51W is at about 10.5 N IMO
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763. kmanislander
11:53 AM GMT on August 25, 2007
Hi Extreme

They can develop in the ITCZ but the further S the harder it is for them to develop
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762. extreme236
11:46 AM GMT on August 25, 2007
hey kman are systems able to develop in the itcz? i know ivan was far south
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761. kmanislander
11:37 AM GMT on August 25, 2007
Quikscat only caught the very far E side of it but that bit does show a veering of winds from S through NE

Yesterday this feature was below 10 but it has now risen above 10 and this means it will now track into the Caribbean. The increase in Lat may also aid in development by allowing it to escape from the ITCZ
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760. kmanislander
11:34 AM GMT on August 25, 2007
good morning

10N 51W seems to be trying to organize



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759. mobilebayrat
6:30 AM CDT on August 25, 2007
Is that spin in the gulf an ULL?

We had a nice rain here yesterday, but a few miles down the raod it was bone dry still.
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758. icepilot
5:15 AM CST on August 25, 2007
Posted By: gippgig at 11:58 PM CST on August 24, 2007.

Is there any possibility of the polar ice cap suddenly breaking up like has happened with a couple of the antarctic ice shelves?


Not under the same types of stresses - the top surface of an antarctic ice shelve can be several hundred feet above sea level and while it is floating on water , it is still attached to land or aground on the bottom or both. Basicly it is a glacier that has flowed out and onto the sea. The sea ice has formed, floating, on the water and, except for "fast" ice, is not attached in any significant way to anything. It also does not rise above the sea level to any great height
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757. extreme236
11:25 AM GMT on August 25, 2007
cant something develop in the itcz? i know ivan was about as far south as the itcz
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756. StoryOfTheCane
11:23 AM GMT on August 25, 2007
There is nothing out there to worry about. Completely quiet.

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755. extreme236
11:17 AM GMT on August 25, 2007
um i just noticed that the nhc said that the wave i was watching yesterday east of south america has become better organized. perhaps something might try to spin up?
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753. underthunder
3:56 AM CST on August 25, 2007
well...I'm officially putting in an order for a tropical storm that will drop about a foot of rain in lets say...3 days...at this point...it's the only thing that will save alabama from becoming the next desert....
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752. PensacolaDoug
8:12 AM GMT on August 25, 2007
Cape Verde Islands = CV
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751. PensacolaDoug
8:05 AM GMT on August 25, 2007
i was just actin wierd.



It aint an act.....:)

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750. aspectre
8:05 AM GMT on August 25, 2007
Okay, what the heck does CV in "CV season" stand for?
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749. hurricanehamster
8:00 AM GMT on August 25, 2007
only just notice but

ecmwf has a tropical depression forming IN japan area

makeing land fall as a t.s!
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747. CaptnDan142
7:55 AM GMT on August 25, 2007
Geez, this midwest flooding is really out of control. What's going to happen if the rain keeps coming like this??

Um, bigger floods? (Sorry, couldn't resist)

One of the storms that went through a couple of days ago had winds at 37mph gusting to 56mph.

A friend in Norfolk, NE sent me pics of the trees that were damaged in her yard. In the background of one pic I could see a tree limb laying on a neighbors SUV.

She said there were trees and limbs down all over town, and the flooding has begun.
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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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