Tropical Storm Danny likely to be named today

By: Dr. Jeff Masters , 1:25 PM GMT on August 26, 2009

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First-light satellite images of the tropical wave (92L) a few hundred miles northeast of the Bahama Islands show that the system has developed an organized surface circulation, and 92L will likely be named Tropical Storm Danny later today. This morning's QuikSCAT pass confirms the presence of a surface circulation, and the satellite saw top winds of 50 mph in a cluster of thunderstorms well east of the center. Wind shear has dropped to the moderate range, 10 - 15 knots. The upper-level low 92L is moving underneath has plenty of dry air in it, and the upper low is injecting this dry air into 92L's west side, keeping and heavy thunderstorm activity from developing on that side. The Hurricane Hunters are in 92L, and have found surface winds up to 57 mph so far this morning. NHC continues to give 92L a high (greater than 50% chance) of developing into a tropical depression by Thursday afternoon.


Figure 1. Water vapor satellite image from 8:15 am EDT 8/26/09 showing dry air associated with an upper-level low pressure system to the west of 92L's center of circulation. Image credit: NOAA/SSD.

The forecast for 92L
As 92L continues to plow through the upper low, the low will weaken, and wind shear is expected to decline to the low range, 5 - 10 knots, by tonight. However, the upper-level low will continue to dump dry, cold air into 92L through Thursday afternoon, slowing down development. By Thursday night, when 92L should be several hundred miles off the coast of northern Florida, the upper-level low may be weak enough and far enough away that 92L will find itself in a region with light upper level anticyclonic winds, which would favor more rapid development. Most of the intensity models, including the GFDL, HWRF, and SHIPS model, forecast that 92L will become a hurricane by Friday. However, this favorable environment will not last long, since a strong trough of low pressure will be approaching the U.S. East Coast on Friday. This trough will bring high wind shear of 20 - 30 knots by Friday night. This trough should be strong enough to turn 92L to the north. The models have come into better agreement keeping 92L offshore as it passes North Carolina, though the storm is certainly capable of giving the Outer Banks a direct hit. As 92L passes North Carolina, it should start heading north-northeast, with a second landfall likely Saturday night or Sunday morning somewhere between Massachusetts and Nova Scotia. At that time, 92L is likely to be a strong tropical storm or weak Category 1 hurricane, with winds in the 55 - 80 mph range. It currently appears that 92L will not bring tropical storm-force winds to the Bahamas or to Florida.

Elsewhere in the Atlantic
The models have been inconsistently predicting formation of several tropical waves coming off the coast of Africa over the next week, and I am going to stop mentioning these forecasts until we get two models predicting the same thing, several model runs in a row.

I'll have an update later today.

Jeff Masters

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Quoting bcwolf303:
WxLogic there are so many different links to charts and maps on StormW and TampaSpins page I am trying to narrow down what I am looking at. It is information overload. I am looking for charts or maps that will help me understand what are the visual clues as far as a tropical wave becoming a named storm. And also any charts or maps that will help me understand steering better. I imagine people have different opinions on which images they find helpful. I'm trying to start with the basics and learn one thing or two things at a time. I'm no pro, obviously just very fascinated by these storms.


I haven't seen him around much this year, probably because I've too busy to do much lurking, but StormJunkie has a page with tons of information - from the basics on up.....
www.stormjunkie.com
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Ike which charts do you follow/ find most helpful?
Member Since: August 23, 2009 Posts: 0 Comments: 16
Acemett...Please don't say the f word...

I'm outa here before I get banned by Taz...see ya...
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Quoting Weather456:


Thanks but the webpage I was looking for. The webpage the image came from.


my bad...here ya go.....
http://my.sfwmd.gov/portal/page?_pageid=3194,21328260,3194_21169354:3194_21260384&_dad=portal&_sche ma=PORTAL
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Quoting IKE:


To me, there's way too many charts on TS's blog.


LOL
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Quoting bcwolf303:
WxLogic there are so many different links to charts and maps on StormW and TampaSpins page I am trying to narrow down what I am looking at. It is information overload. I am looking for charts or maps that will help me understand what are the visual clues as far as a tropical wave becoming a named storm. And also any charts or maps that will help me understand steering better. I imagine people have different opinions on which images they find helpful. I'm trying to start with the basics and learn one thing or two things at a time. I'm no pro, obviously just very fascinated by these storms.


I believe you can start with this one CIMSS... it has a little bit of everything... mostly current data and past... which you can use to correlate with current events... then you can start venturing into Forecast models such as GFS, ECMWF, etc... and making your own deductions...

Finally, read the NHC discussions as they'll give you a lot of information on how High/Lows interact and other weather events and their behavior.
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Quoting IKE:


Hello, from the NW side of 285.

Has it go east of NC/SC and make landfall in New England.

Looks like most of the convection stays on the east side of Danny on the GFS.


Hello from east of 87 and south of 98! Good to see lots of shear in the GOM, sure would be nice if it stayed that way through November!
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Quoting pearlandaggie:
weather456...

http://my.sfwmd.gov/sfwmd/common/images/weather/track.gif


Thanks but the webpage I was looking for. The webpage the image came from.
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Quoting PGIFL:
Weather 456 -
Available from South Florida Water Management Dirict, whose regulations extend into the glades.
FWH


thanks but I actually wanted the webpage
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weather456...

http://my.sfwmd.gov/sfwmd/common/images/weather/track.gif
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502. JLPR
it seems all of Danny's winds are on the north side
the Bahamas seem to have lucked out =]

Member Since: September 4, 2007 Posts: 36 Comments: 5223
501. IKE
Quoting bcwolf303:
WxLogic there are so many different links to charts and maps on StormW and TampaSpins page I am trying to narrow down what I am looking at. It is information overload. I am looking for charts or maps that will help me understand what are the visual clues as far as a tropical wave becoming a named storm. And also any charts or maps that will help me understand steering better. I imagine people have different opinions on which images they find helpful. I'm trying to start with the basics and learn one thing or two things at a time. I'm no pro, obviously just very fascinated by these storms.


To me, there's way too many charts on TS's blog.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting WxLogic:


12Z GFS is bringing that system to the Carib in 120HR or so... or by Monday.


Link?
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498. PGIFL
Weather 456 -
Available from South Florida Water Management Dirict, whose regulations extend into the glades.
FWH
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Quoting JLPR:


does it look like a weak llc? =P

yes I am thinking we will have 94L later today
or sometime tomorrow
Member Since: June 13, 2009 Posts: 2 Comments: 12716
P451...please delete your entries for 2007, 2001,1995, and 1989...much appreciated...
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495. IKE
Quoting WxLogic:


Indeed... also it seems the negative NAO might be starting to kick in as there's more ridging going on... but of course we'll really see if that's the trend as we approach those days.


Agree. I was just fixing to state what you just said. After this coming trough the pattern appears to change. Could be trouble for the Caribbean and GOm if that verifies.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting JLPR:


thank you for the answer im a disaster at steering layers lol


Hehe...
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Great. A hurricane in the Bay of Fundy. Not a pleasant thought.
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WxLogic there are so many different links to charts and maps on StormW and TampaSpins page I am trying to narrow down what I am looking at. It is information overload. I am looking for charts or maps that will help me understand what are the visual clues as far as a tropical wave becoming a named storm. And also any charts or maps that will help me understand steering better. I imagine people have different opinions on which images they find helpful. I'm trying to start with the basics and learn one thing or two things at a time. I'm no pro, obviously just very fascinated by these storms.
Member Since: August 23, 2009 Posts: 0 Comments: 16
Quoting IKE:


Looks like it continues on to the west, or just slightly north of west.

No recurving with that wave through 180 hours.


Indeed... also it seems the negative NAO might be starting to kick in as there's more ridging going on... but of course we'll really see if that's the trend as we approach those days.
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Quoting IKE:


Looks like it continues on to the west, or just slightly north of west.

No recurving with that wave through 180 hours.
no worrries if and when it gets close to florida, im going to turn on my fan and blow it north again, like i'm doing now for danny..
Member Since: August 18, 2009 Posts: 0 Comments: 157
485. NEwxguy 9:46 AM PDT on August 26, 2009
Amy,since when do you try to make your life easier,I thought you liked the more difficult road


point taken...I'm off my game today...thanks for setting me straight...
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487. IKE
Quoting WxLogic:


12Z GFS is bringing that system to the Carib in 120HR or so... or by Monday.


Looks like it continues on to the west, or just slightly north of west.

No recurving with that wave through 180 hours.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
486. JLPR
Quoting WxLogic:


For now it sure looks it will have a the Azores High along with the Bermuda high to push this one through the CATL on a general W to WNW direction for the time being. (subject to change).


thank you for the answer im a disaster at steering layers lol
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Amy,since when do you try to make your life easier,I thought you liked the more difficult road.
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484. JLPR


does it look like a weak llc? =P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting Weather456:
Does anyone know where I get this image



lol... huh!!!
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and then we will have the dreaded f storm

Oh man....can't we just skip f and go onto g...my life would be so much easier....
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Quoting Barbados:


Coudn't agree with you more JLPR. Are there any ridges/high pressure building to steer things westwards or is everything for the time being expected WNW?


For now it sure looks it will have a the Azores High along with the Bermuda high to push this one through the CATL on a general W to WNW direction for the time being. (subject to change).
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Does anyone know where I get this image

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SW shear is just really messing with any chance Danny has to organize.
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Quoting tornadodude:
Great View of Danny
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Quoting JLPR:
so everyone is ignoring the tropical wave south of the CV islands O_O



its looking very good and no comments about it? xD


Couldn't agree with you more JLPR. Are there any ridges/high pressure building to steer things westwards or is everything for the time being expected WNW?
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Quoting bcwolf303:
Was my question so dumb that no response was deemed necessary? Oh well, back to lurking. I can pick up a bit just by reading the blog.


In a way you kind of answer your own question hehe... as you stated... if you look at Tampa's and StormW's page you'll get the most reliable sites most of us use to track these systems. So you can book mark those links they have and check them out any time.

In regards the most reliable model... you'll typically follow the ECMWF as it has been doing well for a long time.
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Good Afternoon

Tropical Update
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YES i love the CMC doomcast runs. Cat 5 into just west of NYC!

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Quoting HopquickSteve:
Morning! So 93L became danny and not 92? With all of these storms so close to each other... How much does someone want to bet that someone starts ranting about the "Fujiwhara Effect" as all of the storms follow the omniscient "XTRP"?

Link


No,92 became Danny,93 was in the SW Carr.
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Great View of Danny
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468. JLPR
and the Ukmet keeps insisting in developing Erika out of the wave south of the CV islands



NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 72 HOURS
FORECAST POSITION AT T+ 72 : 12.4N 34.7W

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
00UTC 29.08.2009 12.4N 34.7W WEAK
12UTC 29.08.2009 13.4N 37.2W WEAK LITTLE CHANGE
00UTC 30.08.2009 13.9N 40.3W WEAK LITTLE CHANGE
12UTC 30.08.2009 14.4N 43.3W WEAK LITTLE CHANGE
00UTC 31.08.2009 15.5N 45.1W WEAK LITTLE CHANGE
12UTC 31.08.2009 16.2N 46.5W WEAK LITTLE CHANGE
00UTC 01.09.2009 16.1N 47.3W WEAK LITTLE CHANGE
Member Since: September 4, 2007 Posts: 36 Comments: 5223

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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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