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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I think our luck is running out as 94L will likely be the first real threat of the year.
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take a look at the track of TD 13

Member Since: May 21, 2006 Posts: 5091 Comments: 115239
just keep all the storms to the east coast this year so they all have a chance to go out to sea.
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759. Relix
Oh wait I made a little... mistake!!!

At 67W it would be at 19N. SOOO.... 63W it would be around 18.2N. Almost direct impact to PR =P.
Member Since: August 3, 2006 Posts: 0 Comments: 2725
That AEW over the Togo area is looking so good because it's still over land. I'll be very interested to see if CV islands report a surface low with it as it passes, though. These waves can look great over WAfrica, only to fizzle out over the very different environment of the EAtl.
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757. Relix
Quoting JRRP:
18 GMT 08/28/09 11.0N 36.0W 25 1010 Invest
00 GMT 08/29/09 11.3N 37.9W 25 1010 Invest


.3N Gain
1.9W Gain

Estimate if current track sticks
At around 60W it would be close to 19.0... of course this is if it keeps going the same way or if the COC doesn't reform, also.. it's a pretty basic thing what I did, but could give an estimate on the track.

Member Since: August 3, 2006 Posts: 0 Comments: 2725
Navy Back up site
Member Since: March 19, 2009 Posts: 0 Comments: 1421
754. JRRP
18 GMT 08/28/09 11.0N 36.0W 25 1010 Invest
00 GMT 08/29/09 11.3N 37.9W 25 1010 Invest
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Good NIght All, What are the chances of 94L coming my way?
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751. Relix
Quoting StormW:
Here ya go...put THIS in motion...look on the continent.

EUMETSAT


Looks impressive
Member Since: August 3, 2006 Posts: 0 Comments: 2725
Methinks 94 isn't immune to a bit of dry air.
(Black on the WV is dry, regardless of what the SAL plot shows.)


Like I said, if it would go ahead and develop, it would recurve earlier. Not sure it can.
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Still lots of options for 94L given its current state and location:

- fizzle out before reaching Lesser Antilles
- shrivel up in the dry air of the E Car
- hang on to rotation and bomb out west of JA
- dawdle along to the WNW, passing near PR and potentially threatening the Bahamas and SE US
- get its act together and head off to the NW into the ATL

or any possible combination u can think of after that.....

The only one I think has a low probability at this point is the first one. I think it will make it at least to 60W as an area of potential development. After that, it will depend on what conditions are like (and IMO, also how far north it is...).
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Hi Storm,

I have seen a few people mention here tonight that there have been no model runs on 94L since this morning. Some have said it is because they are going to drop it. What is your opinion on why there have been no updates?
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745. IKE
...DANNY MOVING NORTH-NORTHEASTWARD AT A FASTER FORWARD SPEED...


11:00 PM EDT Fri Aug 28
Location: 31.4N 74.9W
Max sustained: 40 mph
Moving: NNE at 12 mph
Min pressure: 1006 mb



TROPICAL STORM DANNY DISCUSSION NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL052009
1100 PM EDT FRI AUG 28 2009

DANNY REMAINS A POORLY ORGANIZED TROPICAL STORM. THE STRONGEST
WINDS AND LARGEST AREAS OF CONVECTION ARE STILL WELL SOUTHEAST OF
THE CENTER...ALTHOUGH SOME DISORGANIZED CONVECTION HAS RECENTLY
FORMED NEAR THE CENTER. JUST-RECEIVED QUIKSCAT DATA SHOWS ONE
RELIABLE-LOOKING 35 KT VECTOR SOUTHEAST OF THE CENTER...SO THE
INITIAL INTENSITY REMAINS 35 KT. ANALYSES FROM CIMSS AT THE
UNIVERSITY OF WISCONSIN INDICATE ABOUT 15 KT OF SOUTHWESTERLY
VERTICAL WIND SHEAR AS DANNY IS BECOMING EMBEDDED IN FLOW BETWEEN
AN UPPER-LEVEL ANTICYCLONE NEAR 26N71W AND THE POWERFUL UPPER-LEVEL
TROUGH MOVING NORTHEASTWARD THROUGH THE SOUTHEASTERN UNITED STATES.

DANNY HAS CONTINUED ITS ERRATIC MOTION THIS EVENING. JUST
BEFORE SUNSET...THE EXPOSED CENTER APPEARED TO BE MOVING NORTH-
NORTHEASTWARD OR NORTHEASTWARD. SINCE THEN...THE CENTER HAS
DISAPPEARED UNDER CIRRUS CLOUDS...BUT IT SEEMS TO BE MOVING MORE
NORTHWARD AT A FASTER PACE. THE INITIAL MOTION IS AN UNCERTAIN
020/10. OTHER THAN THAT...THE TRACK FORECAST SCENARIO IS
UNCHANGED. DANNY SHOULD ACCELERATE INTO THE WESTERLIES...MOVING
GENERALLY NORTH-NORTHEASTWARD FOR THE FIRST 24 HR OR SO...FOLLOWED
BY A TURN TO THE NORTHEAST AND EVENTUALLY EAST-NORTHEASTWARD. THE
NEW FORECAST TRACK IS NUDGED TO THE EAST OF THE PREVIOUS TRACK
BASED ON THE INITIAL POSITION AND MOTION...AND LIES ALONG THE LEFT
EDGE OF THE TIGHTLY CLUSTERED TRACK GUIDANCE MODELS THROUGH 48 HR.
THE TRACK CALLS FOR THE CENTER TO PASS EAST OF CAPE HATTERAS IN
ABOUT 12 HR...SOUTHEAST OF CAPE COD IN 24-30 HR...AND NEAR OR OVER
NOVA SCOTIA AND NEWFOUNDLAND IN 36-48 HR.

DANNY IS ABOUT OUT OF TIME TO STRENGTHEN AS A TROPICAL CYCLONE...AS
VERTICAL SHEAR OVER THE SYSTEM IS FORECAST TO INCREASE
SIGNIFICANTLY OVER THE NEXT 12-24 HR. AFTER THAT...THE SYSTEM
SHOULD UNDERGO EXTRATROPICAL TRANSITION. THE INTENSITY FORECAST IS
THE SAME AS THE PREVIOUS ADVISORY...CALLING FOR A LITTLE
INTENSIFICATION WHILE DANNY IS STILL TROPICAL...LITTLE CHANGE IN
STRENGTH THROUGH EXTRATROPICAL TRANSITION...THEN SOME
INTENSIFICATION AS AN EXTRATROPICAL LOW OVER THE NORTH ATLANTIC.

AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT SHOULD ARRIVE IN
DANNY AROUND 06Z TO BETTER DETERMINE THE POSITION AND INTENSITY.
AS DANNY BECOMES EXTRATROPICAL...ITS EXPANDING WIND FIELD MAY
IMPACT THE COAST OF NEW ENGLAND. THESE POTENTIAL IMPACTS WILL BE
HANDLED WITH GALE WARNINGS AND OTHER PRODUCTS ISSUED BY LOCAL NWS
OFFICES IN THAT REGION.

FORECAST POSITIONS AND MAX WINDS

INITIAL 29/0300Z 31.4N 74.9W 35 KT
12HR VT 29/1200Z 34.7N 73.8W 40 KT
24HR VT 30/0000Z 39.5N 70.1W 40 KT
36HR VT 30/1200Z 44.0N 64.5W 40 KT...EXTRATROPICAL
48HR VT 31/0000Z 47.3N 58.1W 40 KT...EXTRATROPICAL
72HR VT 01/0000Z 51.5N 45.0W 40 KT...EXTRATROPICAL
96HR VT 02/0000Z 53.5N 30.0W 45 KT...EXTRATROPICAL
120HR VT 03/0000Z 56.0N 14.0W 50 KT...EXTRATROPICAL

$$
FORECASTER BEVEN

Member Since: June 9, 2005 Posts: 23 Comments: 37858
744. JLPR
Quoting spathy:
I know all are looking at Danny and 94L.
But any thoughts on that next wave a couple of days from African coast?


it looks impressive =\
Member Since: September 4, 2007 Posts: 36 Comments: 5223
"The ensemble mean had been opposing the ensemble mean all week"

I think I am tired...that was goofy.
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Quoting StormW:


Oh...I know you didn't...I just couldn't figure out why I would be Norm...he has hair! LOL!!


Lol. Just the favorite, lovable and witty part.
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Quoting Codaflow:
Weather's holding out just nicely for launch tonight. Cross your fingers folks. There are lots of very tired, but hardworking people out here at KSC.


Fingers and toes crossed! There was some great work done resolving the pv12 valve issue.
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Quoting StormW:


Thanks for answering! A lot of stuff there.

I wish things were different at home so I could go back and finish working toward my degree. But until then...I'll just keep forecasting.

I wish you could, too. I cannot imagine anyone trying to do those courses via the internet, but...

Can you believe that we ran a sensitivity analysis comparing WRF results (with a hurricane) in NWP with 3 different physics packages for the convective parameterization? As undergrads? I promise, I never missed NWP class. (ok, I didn't miss many over the course of years, either, but you get the idea).
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738. JLPR
Quoting CaribBoy:
94L is clearly rotating based on IR satellite loop : Loop


yep
Member Since: September 4, 2007 Posts: 36 Comments: 5223
94L is clearly rotating based on IR satellite loop : Loop
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Quoting homelesswanderer:


Ok. My turn. ????????


Double the ??????. Kids these days...
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734. JLPR
well im starting to get a little nervous with 94L
=\
it keeps heading mostly west and if it goes waaay to west it may end up making the north turn at the Lesser Antilles so I hope it develops already and starts moving wnw or nw =]
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting Stormchaser2007:


They're acting...foolish to put it lightly.

Thats why they're irregulars.


Ok. My turn. ????????
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94L model runs are starting to scare me. I am in Houston and I have a trip planned to Canada on 9/12....I hope this doesn't mess things up.

I know its a long shot and its a ways away but it looks like Ike.
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Quoting Codaflow:
Weather's holding out just nicely for launch tonight. Cross your fingers folks. There are lots of very tired, but hardworking people out here at KSC.
Good to see you again. Thanks as always for the onsite launch information as time permits of course. 'Know you're busy.
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Space Shuttle Discovery is set to launch at 11:59 p.m. EDT tonight! So cool to watch a night launch in Florida!
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Quoting Tazmanian:
92L got name Danny??? that was the bigets move i have evere seen the nhc made in my life Danny dos not even look like a name storm it is sick has a bone why on earth did they name it for a TD would have benn better for this sick liite storm
Taz, Danny would have gotten a name, even if it was STS Danny. It had all the requirements, including at one time 50+ kt winds. Plus it had enough model support to make it worth the name.

It's not the first messy storm we've seen......
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Quoting StormW:


Looking at the current model info on the MJO, there is still upward motion from about 30W to Africa, and a small area of weak downward motion near the Lesser Antilles. So for the most part, we are looking at slight upward to neutral conditions. The model forecast still calls for upward motion over the Atlantic Basin through the 1st week of Sept. I think the models are still having a hard time with a concrete initialization, and that may be what is affecting them.


The ensemble mean had been opposing the regular GFS result all week. I've been calling it the battle of wits. The ensemble mean has been winning all week, too. Seems like GFS is incapable of giving us even a few days of good MJO forecast right now.

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Quoting Codaflow:
Weather's holding out just nicely for launch tonight. Cross your fingers folks. There are lots of very tired, but hardworking people out here at KSC.

Is the shuttle still go for launch?
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Quoting StormW:


???????


I was referring to Norm on Cheers. Every time he walks in the bar everybody greets him like they do you in here. Because he's a favorite and a regular as you are here. Didn't mean nothing bad by it. :)
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Niño 3.4 has been warming up lately.

Member Since: March 19, 2009 Posts: 0 Comments: 1421
Quoting StormW:


Hey aggie!

Been meaning to ask you...how was the MET program you went through?

Well, I have to say, it had it's ups and downs.

We had an excellent exposure to theory and a lacking exposure to real-world application, in my opinion.

My favorite courses in the program happened to be mostly optional (at the time): Atmo chem, NWP, air pollution met
Don't misunderstand me; I enjoyed physical climatology, dynamics, atmo physics, severe, and tropical, but they were so much theory and so little application, I feel that I use them very little. No need to derive the radiative transfer equation at a real job.
Could I whip you up a particulate dispersion model in Fortran, C, Matlab, or IDL using what I learned in air po met and NWP? Sure. Learned how to answer real-world questions in those courses.
Some other things were tough to enjoy.

We had a new prof from Washington State that knew a lot about monsoons in India lecturing a bunch of gulf coast natives about hurricanes. We corrected her hundreds of times.

We had no actual radar study course, though one should have been connected to the severe course.
If I had to do it over again, I would consider A&M, but I might look around at bit harder at the course-style and talk to a few recent grads...somehow. I find U South Alabama to be a neat program with good profs (I know a few) and a decent curriculum (I know a few grads, too).

However, there are few other programs where the school on your degree opens doors as well as one from A&M. The program more than satisfies the requirements for NWS jobs. And the undergrad met program at A&M has a stellar reputation among those in the field.
One huge positive I can say is that I have heard that a lot of the optional courses I took simply are not offered to undergrads in most programs. I don't know of another program that offers Atmo chem. Or one in which undergrads actually run WRF, MM5, and BAMM (yes, we did).

I do have to thank A&M for a lot of those unusual courses available there, likely due to the program's size, as they had a lot do to with the career opportunities I have enjoyed since.
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Quoting mobilegirl81:

Whats with the irregulars here tonight?


They're acting...foolish to put it lightly.

Thats why they're irregulars.
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http://cimss.ssec.wisc.edu/goes/rt/images/conus/band03/usgscb03.09241.0100.gif
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Quoting Stormchaser2007:


??

AS IT MOVES
WESTWARD AT AROUND 15 MPH.
look where it says: "Movement: W at 21 mph"

There's a "transparent" anvil cloud next to the launch site - per NASA TV. What the heck?
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Quoting Stormchaser2007:


Dont mind them.

Whats with the irregulars here tonight?
Member Since: August 31, 2008 Posts: 0 Comments: 833
Quoting canesrule1:
20-30 mph


Whoooa! Usually when they move that fast, doesn't it impede their potential for intensification??
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712. Relix
The slow lat could be an inhibitor as well. Coriolis effect? So many factors... I am tired and rambling now so nevermind me =P
Member Since: August 3, 2006 Posts: 0 Comments: 2725

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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.