Danny still weak

By: Dr. Jeff Masters , 7:32 PM GMT on August 28, 2009

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Tropical Storm Danny continues to look unhealthy, with an exposed low-level center and the main heavy thunderstorms well to the east. The center is oval instead of circular, which may portend that this center will dissipate and a new center will form under the heaviest thunderstorm activity. Danny has more of the appearance of a subtropical storm than a tropical storm on satellite imagery, and this structure will slow down any potential intensification. The amount of heavy thunderstorm activity has increased in the past few hours, though no thunderstorms have formed near the center. The latest Hurricane Hunter mission found one small spot of 45 mph surface winds between 1 - 3 pm EDT today, so Danny may barely qualify as a tropical storm. Danny's center may have begun moving to the north over the past hour, giving confidence that the storm's strongest winds and rain will stay offshore of North Carolina tonight and Saturday morning.


Figure 1. Afternoon satellite image at 3:03 pm EDT of Danny, showing the exposed swirl of clouds where Danny's center is, well displaced from the heaviest thunderstorm activity to the east. The center is oval-shaped and not circular, the sign of a weak circulation.

The forecast for Danny
With wind shear at 15 knots this afternoon, and forecast to increase to 20 knots tonight and 30 knots Saturday morning, it is unlikely Danny will be able to strengthen to more than a 50 mph tropical storm. Dry air from the upper-level low that has been keeping Danny disorganized continues to be a problem for the storm, as well. Most of the intensity forecast models continue to insist Danny will strengthen, but they have been doing a very poor job forecasting the intensity of Danny. With Danny's heavy thunderstorms all on the east side of the storm, it is unlikely that North Carolina or New England will feel tropical storm force winds from Danny when it scoots past on Saturday. Large swells from Danny creating high surf along the beaches of New England will be the primary hazard from the storm.

Massachusetts hurricane history
Two tropical storms have affected Massachusetts in the past decade, though neither of these storms brought sustained winds of tropical storm force (39 mph) to the state. Tropical Storm Beryl of 2006 just missed Cape Cod as a weak tropical storm with 45 mph winds. Beryl brought wind gusts to tropical storm force to Nantucket Island, and a 1 foot storm surge. Tropical Storm Hermine hit southeast Massachusetts on August 31, 2004, as a minimum-strength tropical storm with 40 mph winds. No land stations in Massachusetts reported tropical storm force winds during Beryl. The last time Massachusetts measured tropical storm force winds was in 1997 during that year's version of Tropical Storm Danny. Chatham recorded sustained winds of 44 mph, and Nantucket had 43 mph winds. The last time Massachusetts had hurricane force winds was in 1991 during Hurricane Bob, which hit Rhode Island as a Category 2 hurricane. Provincetown, Massachusetts measured sustained winds of 98 mph, gusting to 115 mph, and Buzzard's Bay received a 15 foot storm surge.

Invest 94L
The well-organized tropical wave (94L) mid-way between Africa and the Lesser Antilles Islands continues to be a threat to develop into a tropical depression in the next day or two. Water vapor satellite loops show that 94L has moistened the region surrounding it considerably today, and the storm is not ingesting as much dry air as this morning. However, visible satellite loops show only a small amount of heavy thunderstorm activity near the circulation center, which is broad and elongated from east to west. Shear is low, about 10 knots, and is expected to remain low, 5 - 10 knots, over the next five days. The waters are warm enough to support development, 27°C, and are expected to remain in the 27 - 28°C range over the next five days. It appears that 94L needs another 1 - 3 days to develop a well-formed circulation and become a tropical depression, given the favorable environment. NHC is giving 94L a medium (30 - 50% chance) of developing into a tropical depression by Sunday. Most of the models predict 94L will Be affected by two troughs of low pressure over the next week, which will pull the storm far enough north so that it will miss the Lesser Antilles Islands. It is then probable that 94L will be forced to the west again as the high pressure ridge steering the storm builds back in. The possible long-term threat to the U.S. East Coast is impossible to evaluate at this time.

I'm in New York City this weekend for my cousin's wedding, so will not be blogging again until Monday morning. In my absence, wundergound's severe storms expert, Dr. Rob Carver, will be posting in my blog Saturday and Sunday.

Jeff Masters

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Quoting Weathermandan:


Does anybody else see some definitive rotation under the convection with Danny, moving SOUTH?


Yep..the big loop de loop maybe.
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I can't wait for the 11pm advisory, if indeed that spin under the convection I'm seeing verifies, but I'm not too convinced because the same thing happened yesterday and it was nothing. Difference is that tonight it looks like there's banding? o.O
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94L, on the other hand, is a little more interesting, imo.

But I'm a generic sort of person.
Not into freakish drama.
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Quoting connie1976:


The same path as Bill?
no he means a, "oh no florida is screwed!" type of path
Danny is about the weirdest freak of a TS I have ever seen.
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Man I just can't wait for that "tropical wave" from Miami to make it up here to Tallahassee on Sept. 7th. GO NOLES
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Quoting Weathermandan:


Does anybody else see some definitive rotation under the convection with Danny, moving SOUTH?


Hmmmmmm...
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Quoting Funkadelic:


Strength is a factor but right now it has a slight WNW movement, and by the time it reaches the islands, it will feel a "Slight" pull north but then flatten out to more of a western track. The only way it makes it into the Carribean is if it falls apart tonight and drifts WSW as an open wave.

Ok thanks, that makes better sense.
Member Since: August 31, 2008 Posts: 0 Comments: 833
Quoting cyclonekid:
Interesting BAMD model sinks Danny to the SE.


94L


Does anybody else see some definitive rotation under the convection with Danny, moving SOUTH?
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000
ABNT20 KNHC 282343
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT FRI AUG 28 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM DANNY...LOCATED ABOUT 300 MILES SOUTH OF CAPE HATTERAS NORTH
CAROLINA.

A BROAD AREA OF LOW PRESSURE LOCATED ABOUT 1035 MILES WEST-SOUTHWEST
OF THE SOUTHERNMOST CAPE VERDE ISLANDS CONTINUES TO PRODUCE
DISORGANIZED SHOWERS AND THUNDERSTORMS. ALTHOUGH THIS SYSTEM HAS
CHANGED LITTLE THIS EVENING...CONDITIONS APPEAR FAVORABLE FOR
GRADUAL DEVELOPMENT OVER THE NEXT COUPLE OF DAYS AS IT MOVES
WESTWARD AT AROUND 15 MPH. THERE IS A MEDIUM CHANCE...30 TO 50
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER ROBERTS/BEVEN


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I am not impressed with 94L right now. It's going to have to slow down to develop some decent convection around the center. On that latest quikscat it looks like a broad circulation with multiple developing centers. Going to be a while before it gets to TD status. This season is so boring. The year of the shear and dry air. Easterlies are killing off these waves coming off Africa. By the time they get to the west something is ready to tear them apart or send em out to sea. There is going to have to be a big pattern change for anything to get going for the remaining of the season. I expected this. This is an El Nino year after all.
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Quoting emeraldcoast:


mobilegirl ... please use restraint, we don't say the I-word around Pensacola Beach !!!!!

Sorry, like the dog.
Member Since: August 31, 2008 Posts: 0 Comments: 833
TROPICAL STORM DANNY INTERMEDIATE ADVISORY NUMBER 10A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL052009
800 PM EDT FRI AUG 28 2009

...DANNY NOW MOVING NORTH-NORTHEASTWARD WITH NO CHANGE IN
ORGANIZATION...

A TROPICAL STORM WATCH IS IN EFFECT FOR THE NORTH CAROLINA COAST
FROM CAPE LOOKOUT NORTHWARD TO DUCK...INCLUDING THE PAMLICO AND
ALBEMARLE SOUNDS. A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM
CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA...IN THIS CASE...
WITHIN 24 HOURS. A TROPICAL STORM WARNING MAY BE REQUIRED FOR
PORTIONS OF THIS AREA TONIGHT.

INTERESTS ELSEWHERE FROM THE CAROLINAS NORTHWARD TO NEW ENGLAND AND
THE CANADIAN MARITIMES SHOULD MONITOR THE PROGRESS OF DANNY.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA
OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR NATIONAL METEOROLOGICAL SERVICE.

AT 800 PM EDT...0000 UTC...THE CENTER OF TROPICAL STORM DANNY WAS
LOCATED NEAR LATITUDE 30.9 NORTH...LONGITUDE 75.1 WEST OR ABOUT
300 MILES...480 KM...SOUTH OF CAPE HATTERAS NORTH CAROLINA AND ABOUT
765 MILES...1230 KM...SOUTH-SOUTHWEST OF NANTUCKET MASSACHUSETTS.

DANNY IS MOVING TOWARD THE NORTH-NORTHEAST NEAR 8 MPH...13 KM/HR.
A GENERAL NORTHWARD TO NORTH-NORTHEASTWARD MOTION IS EXPECTED WITH
AN INCREASE IN FORWARD SPEED DURING THE NEXT COUPLE OF DAYS. ON
THIS TRACK...THE CENTER OF DANNY IS EXPECTED TO PASS OFFSHORE OF
THE OUTER BANKS OF NORTH CAROLINA EARLY SATURDAY...PASS OFFSHORE OF
SOUTHEASTERN NEW ENGLAND ON SATURDAY NIGHT AND MOVE NEAR THE
CANADIAN MARITIMES SUNDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH...65 KM/HR...WITH HIGHER
GUSTS. SOME SLIGHT STRENGTHENING IS POSSIBLE TONIGHT...WITH LITTLE
CHANGE IN INTENSITY EXPECTED ON SATURDAY. DANNY IS EXPECTED TO
BECOME EXTRATROPICAL ON SATURDAY NIGHT.


TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 175 MILES...280 KM
MOSTLY TO THE SOUTHEAST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB...29.71 INCHES.

LARGE SWELLS FROM DANNY ARE EXPECTED TO PRODUCE DANGEROUS SURF
CONDITIONS AND LIFE-THREATENING RIP CURRENTS ALONG THE U.S. EAST
COAST DURING THE NEXT DAY OR TWO. PLEASE CONSULT STATEMENTS ISSUED
BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE FOR MORE
DETAILS.

...SUMMARY OF 800 PM EDT INFORMATION...
LOCATION...30.9N 75.1W
MAXIMUM SUSTAINED WINDS...40 MPH
PRESENT MOVEMENT...NORTH-NORTHEAST OR 30 DEGREES AT 8 MPH
MINIMUM CENTRAL PRESSURE...1006 MB



THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL
HURRICANE CENTER AT 1100 PM EDT.

$$
FORECASTER BEVEN
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Quoting emeraldcoast:


mobilegirl ... please use restraint, we don't say the I-word around Pensacola Beach !!!!!

Or the Caribbean
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Quoting emeraldcoast:


mobilegirl ... please use restraint, we don't say the I-word around Pensacola Beach !!!!!


Or in the Cayman Islands for that matter!!!
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393. Relix

Member Since: August 3, 2006 Posts: 0 Comments: 2716
1st time i have seen the nhc ues this word wish i highlight in bold

000
ABPZ20 KNHC 282333
TWOEP
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
500 PM PDT FRI AUG 28 2009

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

SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A LOW PRESSURE AREA
LOCATED ABOUT 210 MILES SOUTH-SOUTHWEST OF ACAPULCO MEXICO HAVE
BECOME SIGNIFICANTLY BETTER ORGANIZED DURING THE PAST SEVERAL HOURS
AND A TROPICAL DEPRESSION APPEARS TO BE FORMING. IF THIS TREND
CONTINUES...ADVISORIES WOULD BE INITIATED TONIGHT OR TOMORROW
MORNING. THE LOW IS MOVING WEST-NORTHWESTWARD NEAR 10 MPH AND THERE
IS A HIGH CHANCE...GREATER THAN 50 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.
Member Since: May 21, 2006 Posts: 5091 Comments: 114965
Interesting BAMD model sinks Danny to the SE.


94L
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Quoting mobilegirl81:

I know its not Ivan, but when Ivan was where 94L is looks similar.


mobilegirl ... please use restraint, we don't say the I-word around Pensacola Beach !!!!!
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Quoting Funkadelic:


It is not going anywhere near the Carribean hun, most likely scenario will be going north of Puerto Rico, and towards the Bahamas region.

What about the strength being an inhibiting factor on the influence of being pulled north?
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Quoting Funkadelic:


It is not going anywhere near the Carribean hun, most likely scenario will be going north of Puerto Rico, and towards the Bahamas region.


The same path as Bill?
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could that low over Georgia merge with Danny?
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Quoting stormpetrol:

Nice quikscat of 94L , looks like the center is around 11N/35W.pretty defined imo.


Proobably will see red at 8pm.
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Quoting Ameister12:
Danny is looking better.
CoC is looking a litlle less exposed.
I wouldn't say that. Yes, it has some convection to the W of the COC. But, wouldn't give up hopes. Wait till another COC forms under the deep convection. Then we may see somethin impresive. But even then, it may not be a hurricane. :) IMO
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Quoting ackee:
agree wonder if we see another ivan from 94L only time will tell

Its just that Ivan dodged south america, but are upper level winds going to be hostile if it reaches that carribean, that is the question.
Member Since: August 31, 2008 Posts: 0 Comments: 833
Has anyone "done the math" to figure out exactly how fast 94L is moving. It does appear to be flying across the screen on the Visible Sat Loop...
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This is the year of the troughs so the general concensus of models & mets would be a more northerly shift, could very well be the case, sames a similar pattern so far to 2006, rather than 2004, imo.
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379. Relix
Quoting serialteg:
I sense a worked-up met frenzy, just like with Ana and Bill. Relix is already jittery lol


=P it's fun trying to figure where they are going, don't blame me! Haha
Member Since: August 3, 2006 Posts: 0 Comments: 2716
I sense a worked-up met frenzy, just like with Ana and Bill. Relix is already jittery lol
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377. ackee
Quoting mobilegirl81:

I know its not Ivan, but when Ivan was where 94L is looks similar.
agree wonder if we see another ivan from 94L only time will tell
Member Since: July 15, 2008 Posts: 0 Comments: 1371
Quoting Weather456:
A track similar to Dean again is unlikely. The high would have to be very strong and persistent. Some northward motion is expected with 94L but gosh its almost at 40W so it better hurry up.

I know its not Ivan, but when Ivan was where 94L is looks similar.
Member Since: August 31, 2008 Posts: 0 Comments: 833
374. Relix
What I meant with my previous statement was that, well... I think the models were using the 10N lat as a starting point right? 1 degree to the north can change some things. It all depends, its too early and there's no developed system just yet. Tomorrow will quite probably be the day we have our next TD. Also, it's moving at a nice pace. It should be around the Antilles by late Monday, early Tuesday, be it in front or to the north. I am leaning 60% Atlantic, 40% Caribbean. I do think the first through will miss it, but seeing as Dr Master and the models are all stubbornly putting it over the islands I am leaning to that, BUT... I cannot turn a blind eye to the fact it's still to the south with no northerly component at all and still undeveloped.
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Quoting DDR:
Good evening 456
Do you think 94L will make it to the islands?


not sure, maybe a bit closer than Bill but not 100% sure.
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If it reaches the Carribean, will it be sheared in 3 days?
Member Since: August 31, 2008 Posts: 0 Comments: 833
A track similar to Dean again is unlikely. The high would have to be very strong and persistent. Some northward motion is expected with 94L but gosh its almost at 40W so it better hurry up.
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the back E is haveing a vary early Autumn this year
Member Since: May 21, 2006 Posts: 5091 Comments: 114965
Quoting AllStar17:


I do not think it will

I don't think so either, but I don't think 94L will go as far North as the models are suggesting now, but who knows I'm usually far off the mark anyways :)
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368. DDR
Good evening 456
Do you think 94L will make it to the islands?
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367. ackee
I just think 94L will likely miss the trough dont think models have good handle on the system
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Quoting stormpetrol:
94L reminds of Dean in 2007 with all the convection west of COC til it finally got its act together.

The way things are going with the storms wanting to pull north, imo, it probably will not end up where Dean went.
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365. IKE
Quoting PcolaDan:

That's the guy that dumped all the rain here yesterday and dropped pressures a fair amount.


Same here in Defuniak Springs. Heavy rains yesterday afternoon.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting stormpetrol:
94L reminds of Dean in 2007 with all the convection west of COC til it finally got its act together.


why go so far back, just go back a week or two when we had 90L
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94L reminds of Dean in 2007 with all the convection west of COC til it finally got its act together.
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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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