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.

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

Jeff Masters

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I am however gonna call for a recurve of TD6 before I go.
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Aww man,
well played ameister.
;)
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BULLETIN
TROPICAL DEPRESSION SIX ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062011
500 PM EDT FRI AUG 12 2011

...TROPICAL DEPRESSION FORMS NORTH OF BERMUDA...MOVING AWAY FROM THE
UNITED STATES AND BERMUDA...


SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...36.0N 63.9W
ABOUT 260 MI...420 KM N OF BERMUDA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...ENE OR 65 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...1011 MB...29.85 INCHES
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Tropical Depression SIX Storm Archive
...TROPICAL DEPRESSION FORMS NORTH OF BERMUDA...MOVING AWAY FROM THE UNITED STATES AND BERMUDA...
5:00 PM EDT Fri Aug 12
Location: 36.0°N 63.9°W
Max sustained: 35 mph
Moving: ENE at 16 mph
Min pressure: 1011 mb
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Quoting CybrTeddy:
TD6 on NHC site, predicted to peak at 45 mph. Seems reasonable.
I agree with with their reasoning. Not enough time to become anything big, but just enough to knock off another name.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
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OK now that the boss has left and left tigger in charge I'm gonna bounce on outa here too. Have a good weekend everyone.
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Seems they aren't ruling out the possibility of it becoming a 60 mph storm.

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TD6 on NHC site, predicted to peak at 45 mph. Seems reasonable.
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000
WTNT21 KNHC 122051
TCMAT1

TROPICAL DEPRESSION SIX FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062011
2100 UTC FRI AUG 12 2011

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL DEPRESSION CENTER LOCATED NEAR 36.0N 63.9W AT 12/2100Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE EAST-NORTHEAST OR 65 DEGREES AT 14 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1011 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 36.0N 63.9W AT 12/2100Z
AT 12/1800Z CENTER WAS LOCATED NEAR 35.7N 64.7W

FORECAST VALID 13/0600Z 37.0N 61.4W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 40NE 50SE 40SW 0NW.

FORECAST VALID 13/1800Z 38.5N 57.8W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 60SE 50SW 0NW.

FORECAST VALID 14/0600Z 39.8N 53.9W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 60SE 50SW 0NW.

FORECAST VALID 14/1800Z 40.6N 49.8W...POST-TROP/EXTRATROP
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 60NE 75SE 50SW 20NW.

FORECAST VALID 15/1800Z...MERGED WITH FRONT

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 36.0N 63.9W

NEXT ADVISORY AT 13/0300Z

$$
FORECASTER CANGIALOSI/STEWART
Forecast to be 45 mph Franklin then die in 2 days
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000
WTNT21 KNHC 122051
TCMAT1

TROPICAL DEPRESSION SIX FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062011
2100 UTC FRI AUG 12 2011

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL DEPRESSION CENTER LOCATED NEAR 36.0N 63.9W AT 12/2100Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE EAST-NORTHEAST OR 65 DEGREES AT 14 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1011 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 36.0N 63.9W AT 12/2100Z
AT 12/1800Z CENTER WAS LOCATED NEAR 35.7N 64.7W

FORECAST VALID 13/0600Z 37.0N 61.4W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 40NE 50SE 40SW 0NW.

FORECAST VALID 13/1800Z 38.5N 57.8W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 60SE 50SW 0NW.

FORECAST VALID 14/0600Z 39.8N 53.9W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 60SE 50SW 0NW.

FORECAST VALID 14/1800Z 40.6N 49.8W...POST-TROP/EXTRATROP
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 60NE 75SE 50SW 20NW.

FORECAST VALID 15/1800Z...MERGED WITH FRONT

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 36.0N 63.9W

NEXT ADVISORY AT 13/0300Z

$$
FORECASTER CANGIALOSI/STEWART
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NHC issuing advisories on TD SIX
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000
WTNT21 KNHC 122051
TCMAT1

TROPICAL DEPRESSION SIX FORECAST/ADVISORY NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062011
2100 UTC FRI AUG 12 2011

THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.

TROPICAL DEPRESSION CENTER LOCATED NEAR 36.0N 63.9W AT 12/2100Z
POSITION ACCURATE WITHIN 20 NM

PRESENT MOVEMENT TOWARD THE EAST-NORTHEAST OR 65 DEGREES AT 14 KT

ESTIMATED MINIMUM CENTRAL PRESSURE 1011 MB
MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT.
WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL
MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT.

REPEAT...CENTER LOCATED NEAR 36.0N 63.9W AT 12/2100Z
AT 12/1800Z CENTER WAS LOCATED NEAR 35.7N 64.7W


FORECAST VALID 13/0600Z 37.0N 61.4W
MAX WIND 35 KT...GUSTS 45 KT.
34 KT... 40NE 50SE 40SW 0NW.

FORECAST VALID 13/1800Z 38.5N 57.8W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 60SE 50SW 0NW.

FORECAST VALID 14/0600Z 39.8N 53.9W
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 50NE 60SE 50SW 0NW.

FORECAST VALID 14/1800Z 40.6N 49.8W...POST-TROP/EXTRATROP
MAX WIND 40 KT...GUSTS 50 KT.
34 KT... 60NE 75SE 50SW 20NW.

FORECAST VALID 15/1800Z...MERGED WITH FRONT

REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 36.0N 63.9W

NEXT ADVISORY AT 13/0300Z

$$
FORECASTER CANGIALOSI/STEWART
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting leofarnsworth:
Should TD6 end up a named storm, it would be the third, I guess they are called, 'cut off lows' that the models missed. It is concerning that meteorologists are so reliant on their models that they repeatedly miss these obvious situations.


How did the meteorologists miss this one? The NHC had this area highlighted for the past 3 days when it had little model support.
Member Since: July 15, 2006 Posts: 17 Comments: 10160
Quoting P451:
IR wise not the coldest cloud tops with TD6



Still not convinced about the frontal system issue.



It was the same way with Cindy though, so it's probably not enough to go against classifying it. Well, take away the "probably", as NHC classified it :P
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Quoting angiest:


Is either system close enough to be considered a CV storm if they suddenly developed today?

One or both may develop, but it doesn't look like either one is a true CV storm at this point.


They would still develop pretty far out the waves are African waves unlike 94 l and td 6
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Tropical Storm soon? Why not. Not seeing much in the way of Dry Air.
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This is really not something you see every day...4 tropical disturbances in the Atlantic with only one tropical depression in the Western Pacific...

Member Since: July 15, 2006 Posts: 17 Comments: 10160
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Should TD6 end up a named storm, it would be the third, I guess they are called, 'cut off lows' that the models missed. It is concerning that meteorologists are so reliant on their models that they repeatedly miss these obvious situations.
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TD06
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Quoting Floodman:
OKay kids, I'm out...got work to finish, errands to run, etc...try not to burn the joint down while I'm out, okay?


Leave Tigger in charge - we'll be fine.
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OKay kids, I'm out...got work to finish, errands to run, etc...try not to burn the joint down while I'm out, okay?
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I think this year will be a North and East gulf year(with some storms sneaking into west gulf, and CV storms will do an earl track, but some might hit the US...
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Quoting weatherh98:


Yet it still may be


Is either system close enough to be considered a CV storm if they suddenly developed today?

One or both may develop, but it doesn't look like either one is a true CV storm at this point.
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Quoting tiggeriffic:


roflmbo...i have been known to fly off the handle but never spin outta control lol...never would get mad at ya Flood...MUAH


Or me you, hon...
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TD6 seems to be an entity unto it's own, evident by the outflow appearing to the north of the surface low... i think seeing that might have triggered the classification. it is attached to the frontal system, yet has a distinct consolidation separated from it.
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Quoting P451:


I'm not so sure if it is fully detached. Would like to have a real time surface analysis. On satellite it's clearly interacting with the frontal system.

Cindy seemed attached for days as did Bret...in fact they were on the same front.

While all three are/were clearly tropical lows all three still interacted with the frontal systems they were born from - and that would appear to go against the NHC guidelines.

I think they should be named. I just think the rule needs to be updated in some form. In it's present form these are three systems that violate the rule put in place by the same agency that upgraded the systems.


Well, if the system has a warm core and has its own closed low, that may make it hard to say it is still part of the front, even if they are moving in tandem. That front has a cold core low attached to it somewhere, and any other lows that may be attached to it should be cold core as well.
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Quoting angiest:


92L and 93L each receive a false start penalty for making think the CV season was here.


Yet it still may be
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Quoting Ameister12:
First advisory on TD6 should be out in a couple minutes.

Get your fingers on that F5 key.


My finger is glued to it.
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Tropicfreak,
i only gave 94L A/B Choices cuase after the weekend, it will only have maybe a day before the front that picks up TD6 will pick 94L up...
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We are getting hammered by a thunderstorm here....Gusts have to be over 40 MPH. Its exactly like a tropical storm - torrential rain, strong wind, loud...
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Quoting ncstorm:


which goes to show you, weather is unpredictable..


You are exactly right, mother nature don't care what the models say, she does her own thang!
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First advisory on TD6 should be out in a couple minutes.

Get your fingers on that F5 key.
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Well it has been fun. Ya'll keep a "weather eye" on the tropics for me during the weekend. I will be occassionally turning on whatever weather channel shows the satelitte images. See you on Monday. Play nice:)
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Quoting Floodman:


Uh huh...uncontrolled force of nature; sort of a Hurricane Tig? I can see that...remind to try to stay on your good side


roflmbo...i have been known to fly off the handle but never spin outta control lol...never would get mad at ya Flood...MUAH
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A very interesting start to July-August with several tropical storms and this current pseudo "cluster" of hurricane wannabees headed out into the Central Atlantic (with the exception of the potential future of 93L). Gonna be really interesting to see what happens when the real CV big dog hurricanes start forming and where they will end up going but it is certainly way too early to declare a season of fishes like last year. The overall pattern is never etched in stone, nor, completely identical to a prior or analog year.
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Quoting tropicfreak:
95L was probably the least expected to become Franklin, until today.


92L and 93L each receive a false start penalty for making think the CV season was here.
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Quoting tropicfreak:
95L was probably the least expected to become Franklin, until today.

As they say in sports, a big upset.


which goes to show you, weather is unpredictable..
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95L was probably the least expected to become Franklin, until today.

As they say in sports, a big upset.
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Quoting tiggeriffic:


roflmbo...sure ya did...like i said...i resemble that remark...never have been one to be controlled lol


Uh huh...uncontrolled force of nature; sort of a Hurricane Tig? I can see that...remind to try to stay on your good side
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Quoting TampaTom:
Would this Franklin work?



No, wait, this is the male Franklin name...

I'm part of your Chain of Fools...


Ever since I got Franklin the Turtle stuck in my head for this storm, I will have a hard time taking it too seriously. Fortunately, it looks like TD6 will become Franklin and be a minimal threat to anyone.
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Quoting weatherh98:


What's that???


..That's Bret.
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Quoting weatherh98:


What's that???


Tropical Storm Bret.
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Quoting Stormchaser2007:
Similar to Bret...



What's that???
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Quoting CybrTeddy:
ZCZC MIATCDAT1 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM FRANKLIN DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT SAT JUL 23 2005

FRANKLIN...THE STORM...NOT THE FORECASTER...HAS BECOME A LITTLE
BETTER ORGANIZED OVERNIGHT.


so how do you know that FRANKLIN the FORECASTER didn't clean out his closet and become better organized too? snicker snicker
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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.