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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I'll have a new post by 1pm Saturday.

Jeff Masters

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The 12pmATCF on 93L is absurdly late, possibly even stopped. So...

19.5n50.0w has been re-evaluated&altered for 92L's_12pmGMT_ATCF
19.3n50.5w, 19.5n53.2w are now the most recent positions

25.4n56.1w, 25.7n57.1w, 26.4n58.4w have been re-evaluated&altered for 94L's_12pmGMT_ATCF
25.4n56.2w, 25.8n57.2w, 26.4n58.3w, 27.1n59.4w are now the most recent positions

Starting at 12August_12pmGMT and ending at 13August_12pmGMT

The westernmost grouping of red dots represents 94L's path,
and the easternmost grouping represents 92L's path.

Copy&paste 25.0n55.4w, 25.4n56.2w, 25.8n57.2w, 26.4n58.3w, 27.1n59.4w, bda, 17.8n45.1w, 18.6n46.9w, 19.1n48.7w, 19.3n50.5w, 19.5n53.2w, bgi, pls into the GreatCircleMapper to make your own map to tinker with.

The previous mapping (for 13August_6amGMT)

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37.3n61.2w has been re-evaluated&altered for TS.Franklin's_12pmGMT_ATCF
37.4n60.8w, 38.6n58.9w are now the most recent positions

Starting at 12August_12pmGMT and ending at 13August_12mGMT

The northernmost line-segment is the straightline projection

TropicalStormFranklin's travel-speed was 22.2mph(35.7k/h) on a heading of 50.8degrees(NE)
Using straightline projection of the travel-speed&heading derived from the ATCF coordinates for 6amGMT then 12pmGMT :
TS.Franklin was headed toward passage over Gortaforia,Ireland ~4days14hours from now

Copy&paste 34.7n66.7w, 35.5n64.7w-36.2n62.6w, 36.2n62.6w-37.4n60.8w, 37.4n60.8w-38.6n58.9w, kir, 37.4n60.8w-52.03n10.1w into the GreatCircleMapper for more info

The previous mapping (for 13August_6pmGMT)
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1608. ncstorm
Quoting GTcooliebai:
It had the makings of another Andrew if that would've happened. Most of the area around Tampa is either at or below sea level, so storm surge would be the worst part of the storm for us.


Yes, his grandmother was reinforcing her home with as many sand bags as she could..it was stressed that everyone do this because they knew the flooding was going to be terrible..
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Quoting GTcooliebai:
It had the makings of another Andrew if that would've happened. Most of the area around Tampa is either at or below sea level, so storm surge would be the worst part of the storm for us.


Don't forget all the GLASS downtown!
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Invest 98E seems to be getting it's act together nicely. Seems like it could be a threat later on to the Hawaiian islands if it develops.





1. AN AREA OF LOW PRESSURE CENTERED ABOUT 1075 MILES SOUTHWEST OF THE
SOUTHERN TIP OF BAJA CALIFORNIA CONTINUES TO SHOW SIGNS OF
ORGANIZATION. CONDITIONS APPEAR TO BE CONDUCIVE FOR A SLOW
DEVELOPMENT OF THIS SYSTEM DURING THE NEXT COUPLE OF DAYS. THIS
SYSTEM HAS A MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL
CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WEST-SOUTHWESTWARD OR
WESTWARD AT AROUND 10 MPH.
Member Since: June 21, 2010 Posts: 0 Comments: 528
1605. ncstorm
Quoting tropicfreak:


Models have been really consistent in taking it towards Bermuda, they may need to watch this..

yes I agree..it seems storms have ramped up near Bermuda this season..
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Quoting ncstorm:


my son was in Tampa at the time when Charley was supposed to hit and they had closed the airports down..they were predicting it to be very bad in Tampa if Charley had come through there..I hate it for the folks that did get Charley but at the same time, I think it would have been much worse if it came in at Tampa..
It had the makings of another Andrew if that would've happened. Most of the area around Tampa is either at or below sea level, so storm surge would be the worst part of the storm for us.
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Quoting bohonkweatherman:
I am thinking end of August or early Sept. but I have been hearing this for like 6 months now. :)


Lol. Yeah. You may be right though. September is when Texas gets most of its landfalls. So maybe that's a sign it will break down. :)
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1602. ncstorm


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Quoting bohonkweatherman:
I am thinking end of August or early Sept. but I have been hearing this for like 6 months now. :)

The Llano river watershed is what we need to get this rain, even if it doesn't make it to Austin (suicide by Hill Country). Large squall lines like this tend to 'trip' when falling into the hills, dump their H20 load, then dissipate. This watershed is the quickest route to putting water into the Highland Lakes.
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Quoting Patrap:
Size matters greatly in a Hurricane...always,,
LOL best laugh of the day so far.
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Quoting ncstorm:






Models have been really consistent in taking it towards Bermuda, they may need to watch this..
Member Since: September 2, 2006 Posts: 110 Comments: 6814
Quoting Vincent4989:
INITIATE MERGE ALARM!
The one prediction I made about 94L yesterday, was that it would slow down and wait for 92L. That's what I would of expected, based upon past observations of two systems about to merge.

Further, I believe they'll both annihilate one another, and move westward as a giant wave into the GOM.

From there is beyond my ability to guess.

Our first Fujiwara of the season?
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1597. Patrap
Size matters greatly in a Hurricane...always,,
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1596. ncstorm
Quoting GTcooliebai:
And it happened on a Friday the 13th, you guys were unlucky, folks in Tampa Bay got lucky!


my son was in Tampa at the time when Charley was supposed to hit and they had closed the airports down..they were predicting it to be very bad in Tampa if Charley had come through there..I hate it for the folks that did get Charley but at the same time, I think it would have been much worse if it came in at Tampa..
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Quoting charlottefl:
Morning everyone, hard to believe it's been 7 years since Charley made landfall here:



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
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1594. yoboi
Quoting jasoniswildman20x1:
fish storm and out to sea


where is it going
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Quoting stillwaiting:
do they ever really come to our area???,macdill has the sheilds up!!
sorry to say, but I believe our luck will run out soon enough.
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Quoting hurricanejunky:
On the 7th anniversary...

Remembering Hurricane Charley: http://bit.ly/nsPFSf








Member Since: September 2, 2006 Posts: 110 Comments: 6814
Quoting charlottefl:
Morning everyone, hard to believe it's been 7 years since Charley made landfall here:

Please don't remind me, you're making me feel so old.
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Quoting charlottefl:
Morning everyone, hard to believe it's been 7 years since Charley made landfall here:

And it happened on a Friday the 13th, you guys were unlucky, folks in Tampa Bay got lucky!
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Quoting GPackwood:


Rain in Dallas! Not Houston, unfortunately.


All I have to do is book a flight that goes thru Houston in the PM and I can guarantee I will have a weather delay! Anybody want to pay for my trip to Vegas? I will go thru Houston on my way there and back just for you! Actually, I could always go to NOLA via Houston on Continental (if I was desperate.) Guaranteed rain.

Seriously, I empathize and sympathize with you people. S FL is still in a drought but at least we have been getting rain. I remember the year FL was burning (was it around 2000?), though, and it was NO FUN!
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1588. ncstorm




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Quoting AtHomeInTX:


Yeah, yeah, I know. I still want it to break down. Lol. So I'm day dreaming. But it could happen. One day. Maybe. :)
I am thinking end of August or early Sept. but I have been hearing this for like 6 months now. :)
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1586. gtodude
Quoting charlottefl:
Morning everyone, hard to believe it's been 7 years since Charley made landfall here:



Yes it is amazing to think that 7 years ago was a really horrible time for a lot of us here in Punta Gorda/Port Charlotte as well as other places too. It's amazing to see Punta Gorda standing tall after what had happened. The rebuild of Charlotte County as a whole has been one of great leaps and bounds. In fact, IMHO, downtown Punta Gorda is much better now than prior to Charley.
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http://www.stormsurfing.com/cgi/display.cgi?a=carib _height

Caribbean wave forecast. Uses GFS.
Member Since: August 28, 2008 Posts: 0 Comments: 250
Quoting charlottefl:
Morning everyone, hard to believe it's been 7 years since Charley made landfall here:



True that brotha. I was in SE Cape Coral and it was a wild couple of hours.
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Quoting bohonkweatherman:
The upper-level high left southeast Arizona last night and is centered east of El Paso this morning. It's return towards Central Texas will be marked by no rain chances after today along with continued triple-digit heat. Details can be found on your YNN 8 Day Forecast.


Yeah, yeah, I know. I still want it to break down. Lol. So I'm day dreaming. But it could happen. One day. Maybe. :)
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Quoting AussieStorm:

Sorry, was trying to be humorous.

lol
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I have to be somewhere in half an hour so must sign off now but will drop in later to see what's going on.

BFN
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Quoting Jedkins01:
Told you guys these things weren't coming to Florida! lol
do they ever really come to our area???,macdill has the sheilds up!!
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Quoting WeatherNerdPR:

lol So?

Sorry, was trying to be humorous.
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Quoting Chicklit:
Hi everyone...I see we finally have rain in Texas!




Rain in Dallas! Not Houston, unfortunately.
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Quoting CybrTeddy:


I agree, here's the latest MJO forecast from the Ensemble GFS. We'll be seeing upward motion entering our basin pretty good soon, that will cause less sinking dry air around 93L to lift and we'll see gradual organization in the Caribbean if it attempts to develop into a tropical cyclone. But you are right, in terms of a threat to land, things are pretty quiet and should remain so the next 48 hours.


The MJO is very close and it is forecast to hang around for quite some time. We could see a two to three week period of heightened activity starting in a couple of days.
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Quoting emcf30:


There has only been 1 fish storm so far this year not counting what Franklin will end up doing.

Correct, Cindy has been the only non land affecting storm so far.

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Quoting AussieStorm:

That's the WU symbol and web address. lol

lol So?
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Quoting AtHomeInTX:
C'mon high BREAK DOWN! Lol



Monitoring possible gulf system in the Tropics...

Posted: Aug 13, 2011 6:49 AM CDT
By Patrick Vaughn

A tropical wave around Latitude 12N...Longitude 34W will be monitored closely over the coming week. While there are three other systems in the Tropical Atlantic, it appears that they will not make it to the Gulf of Mexico (GOM). The fourth system has a decent chance to do so. It appears weak at this time, but there are signs, from model forecasts, that it will develop. This forecast is based upon the reliable European Model. The wave is expected to move into the Eastern Caribbean Monday Night, August 16th. The pivotal day will be a week later on Monday Night August 22nd. From there, it becomes murky on where the storm will head. It appears there are two possible tracks it could take. During this time, blocking upper-level high pressure will be over Texas and over the Bahamas. The storm may turn north and move in-between the two highs towards Mobile to the Florida Panhandle in a weakness. The second possible path will be to just continue moving west, cross the Yucatan and slide under the Texas High and make a final landfall in Mexico. Should the high over Texas weaken then things will become interesting. At this point, though it looks like Southeast Texas is in good shape, but we will closely monitor model trends over the coming week.


The upper-level high left southeast Arizona last night and is centered east of El Paso this morning. It's return towards Central Texas will be marked by no rain chances after today along with continued triple-digit heat. Details can be found on your YNN 8 Day Forecast.
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Hesitant about even posting this, scared I'll run it away :P


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Quoting kmanislander:


Good morning. Hot and sunny. The daily shower of rain.
Pretty much routine for now, and let's hope it stays that way although this could be a potentially dangerous year for the Caribbean.

Right now the Atlantic is fairly stable aloft which is acting to inhibit TS formation but that is unlikely to last for much longer.


I agree, here's the latest MJO forecast from the Ensemble GFS. We'll be seeing upward motion entering our basin pretty good soon, that will cause less sinking dry air around 93L to lift and we'll see gradual organization in the Caribbean if it attempts to develop into a tropical cyclone. But you are right, in terms of a threat to land, things are pretty quiet and should remain so the next 48 hours.
Member Since: July 8, 2005 Posts: 259 Comments: 23012
On the 7th anniversary...

Remembering Hurricane Charley: http://bit.ly/nsPFSf
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1569. emcf30
Quoting prcane4you:
How many fish storms this year? All of them.


There has only been 1 fish storm so far this year not counting what Franklin will end up doing.
Member Since: August 7, 2010 Posts: 0 Comments: 1933
Hi everyone...I see we finally have rain in Texas!


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Quoting CybrTeddy:
Good morning kman, how are things in your area?


Good morning. Hot and sunny. The daily shower of rain.
Pretty much routine for now, and let's hope it stays that way although this could be a potentially dangerous year for the Caribbean.

Right now the Atlantic is fairly stable aloft which is acting to inhibit TS formation but that is unlikely to last for much longer.
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Quoting bohonkweatherman:
Austin does not have a chance of rain today, High Pressure moving East from West Texas today is suppose to dominate? We shall see, highs the next 7 to 10 days 105 to 107, darn high pressure system. Rain may get within 100 miles of Austin though if not closer.

If that storm can make it another 100 miles, we should have enough moisture across a widespread area to encourage the 4pm convective tstorms, further destabilizing the high for at least a few days.
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Quoting WeatherNerdPR:

92L...

That's the WU symbol and web address. lol
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Good morning kman, how are things in your area?
Member Since: July 8, 2005 Posts: 259 Comments: 23012
Quoting txjac:



Hopefully it holds together and we get rain ...I cant believe how excited I am just for rain and clouds ...hopefully thunder too ...love thunder
Austin does not have a chance of rain today, High Pressure moving East from West Texas today is suppose to dominate? We shall see, highs the next 7 to 10 days 105 to 107, darn high pressure system. Rain may get within 100 miles of Austin though if not closer.
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Quoting gulfbreeze:
What is that in the lower right?

You need an eye exam..... He already said it was in the lower right when he posted the image.
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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.