Danielle a hurricane; TD 7 forming off coast of Africa

By: Dr. Jeff Masters , 2:18 PM GMT on August 24, 2010

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Hurricane Danielle has stopped intensifying and is now looking a bit ragged this morning, but remains a respectable Category 1 hurricane with 80 mph winds. The intensity of Danielle's heavy thunderstorms has waned in the past few hours, and the organization of the storm is less impressive. This is probably due do strong upper-level winds out of the west that are creating a moderate 10 - 20 knots of wind shear, and injecting some of the dry air from the Saharan Air Layer (SAL) that surrounds Danielle. Danielle is over warm 28°C water, but is far from any land areas.


Figure 1. Morning satellite image of Tropical Storm Danielle (left side of image) and the forming Tropical Depression Seven (right side of image.)

Forecast for Danielle
A powerful trough of low pressure over the mid-Atlantic Ocean will begin to pull Danielle more to the northwest by Wednesday, keeping Danielle well to the east of Bermuda. Most of the models predict that this trough will be strong enough to fully recurve Danielle out to sea. It is possible that Danielle could eventually threaten Newfoundland, Canada, but it currently does not appear that any other land areas will be at risk from this storm. History suggests that a storm in Danielle's current location has only a 20% chance of making landfall on the U.S. East Coast. If Danielle passes east of Bermuda, as forecast, these percentages drop to less than 5%. As far as intensity goes, it is looking unlikely that Danielle will attain major hurricane status (115+ mph winds.) There is enough dry air and wind shear affecting the storm today that it will take several days for the storm to recover its strength, making it less likely the storm can hit Category 3.

The formation of Danielle is remarkable in this it was successfully forecast by the GFS model nearly two weeks in advance. The ECMWF and NOGAPS models also did a good job of predicting Danielle's formation a week in advance. The models are getting better and better each year at forecasting genesis of tropical cyclones, though a successful 1-week forecast of genesis is still a rarity. For example, none of the models foresaw the development of 96L until just 3 - 4 days ago.


Figure 2. Plot showing historically the percent chance of a tropical cyclone in a given location impacting the U.S. East Coast. For storms in Danielle's current position (orange hurricane symbol), about 20% of them go on to hit the U.S. East Coast. For storms in 96L's current location (red circle with a "?" in it), the odds are also 20%. Image credit: Bob Hart, Florida State University.

96L (soon to be Tropical Depression Seven)
Satellite images suggests that a tropical wave (96L) that emerged off the coast of Africa yesterday morning has developed a closed circulation, low-level spiral bands, and an increasing amount of heavy thunderstorms. While this morning's ASCAT pass does not show a clear closed circulation, satellite estimates of 96L's strength support calling this a 30 mph tropical depression. It is likely that this storm will be designated Tropical Depression Seven later today. 96L is already bringing heavy rain and strong, gusty winds to the southern Cape Verde Islands. Winds were sustained at 26 mph at Mindelo in the northwest Cape Verde Islands this morning, and 24 mph at Praia, the station closest to the center of 96L. Both stations were reporting widespread dust, due to strong winds blowing Saharan dust from the coast of Africa. However, water vapor satellite images show that only a modest amount of dry air is accompanying this dust, and dry air is currently not a major detriment to 96L. Wind shear is about 10 - 20 knots, and sea surface temperatures are warm, 28°C.

Forecast for 96L/Tropical Depression Seven
Wind shear is predicted to remain low, 5 - 10 knots, for the next four days. SSTs will cool a bit to 27°C by Thursday, but this is still above the 26.5°C threshold for hurricane development. Dry air will probably be the main inhibiting factor for 96L. Most of the intensity forecast models bring 96L to hurricane strength by four days from now, and this is a reasonable forecast. 96L should become Tropical Storm Earl later today or on Wednesday, and will probably bring sustained winds of 40 mph to the southernmost Cape Verdes Islands tonight and Wednesday.

The long range fate of 96L remains unclear. The storm is being steering by the same ridge of high pressure steering Danielle, and will initially follow a track similar to Danielle. 96L may encounter the cold waters stirred up by Danielle at times this week, inhibiting development. As 96L approaches the central Atlantic five days from now, the storm will encounter the same mid-Atlantic trough that will be steering Danielle, and 96L should turn more to the northwest. It is unclear at this point whether this trough will be strong enough to fully recurve 96L out to sea, east of Bermuda. This will, in part, depend upon how strong Danielle gets. A stronger Danielle is likely to create more of a break in the ridge of high pressure steering 96L, encouraging the storm to turn north and recurve out to sea. A weaker Danielle will make 96L more likely to miss recurvature, and follow a track to the west or west-northwest towards the U.S. East Coast early next week. History suggests that a storm in 96L's current location has only a 20% chance of making landfall on the U.S. East Coast.

When will the Caribbean and Gulf of Mexico get active?
The large scale atmospheric circulation over the Caribbean and Gulf of Mexico currently features relatively dry, stable, sinking air. This is due, in part, to the Madden-Julian oscillation (MJO). The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased. The latest MJO forecast from the GFS model calls for the wet phase of the MJO to move into the Caribbean during the first week of September. However, keep in mind that forecasts of MJO activity 1 - 2 weeks in advance are not very skillful. The GFS model forecast of MJO activity made two weeks ago did fairly well for the first week, but poorly for the second week of the forecast.

Tropical Storm Frank spares Mexico
Over in the Eastern Pacific, Tropical Storm Frank has moved away the coast far enough from the Mexican coast to no longer pose a heavy rainfall threat, and all tropical storm warnings have been dropped.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. I'll focus on Danielle, Earl, and Frank, and discuss the possibilities of a hyperactive Atlantic hurricane period coming during the first week of September.

Today's show will be 30 - 45 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

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Try this again, NHC did a forecast on 96L

18Z Interpolated


AL 96 2010082418 03 OFCI 0 130N 253W 30 0 LO
AL 96 2010082418 03 OFCI 12 138N 283W 35 0 DB
AL 96 2010082418 03 OFCI 24 146N 313W 40 0 DB
AL 96 2010082418 03 OFCI 36 156N 343W 47 0 DB
AL 96 2010082418 03 OFCI 48 166N 370W 54 0 DB
AL 96 2010082418 03 OFCI 48 166N 370W 54 0 DB
AL 96 2010082418 03 OFCI 60 176N 396W 59 0
AL 96 2010082418 03 OFCI 60 176N 396W 59 0
AL 96 2010082418 03 OFCI 72 184N 422W 64 0 DB
AL 96 2010082418 03 OFCI 72 184N 422W 64 0 DB
AL 96 2010082418 03 OFCI 84 192N 449W 69 0
AL 96 2010082418 03 OFCI 96 201N 473W 72 0 DB
AL 96 2010082418 03 OFCI 108 211N 493W 72 0
AL 96 2010082418 03 OFCI 120 223N 510W 70 0 DB
Member Since: Posts: Comments:
Quoting palmasdelrio:
According to the latest coordinates, 96 is moving SW. Any ideas on whether it's going to move in the same direction as Danielle, or is it going to continue to the west later on?


In the early stages with invests, the center position tends to get jumped around by the atcf

does not necessarily mean it is moving in that direction, just that they are relocating the center
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694. xcool
WHXX01 KWBC 241823
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1823 UTC TUE AUG 24 2010

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL962010) 20100824 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
100824 1800 100825 0600 100825 1800 100826 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 13.0N 25.3W 13.7N 28.5W 14.5N 31.9W 15.0N 35.0W
BAMD 13.0N 25.3W 14.0N 27.6W 14.9N 30.0W 15.9N 32.4W
BAMM 13.0N 25.3W 14.0N 27.9W 15.1N 30.9W 16.1N 33.9W
LBAR 13.0N 25.3W 13.4N 28.6W 14.1N 32.3W 14.8N 35.8W
SHIP 30KTS 38KTS 47KTS 56KTS
DSHP 30KTS 38KTS 47KTS 56KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
100826 1800 100827 1800 100828 1800 100829 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 15.8N 37.8W 16.9N 43.3W 17.6N 49.2W 18.0N 54.7W
BAMD 17.1N 34.7W 19.1N 39.1W 21.0N 43.0W 22.9N 46.7W
BAMM 17.2N 36.8W 18.5N 42.5W 19.2N 48.2W 19.7N 53.5W
LBAR 15.8N 39.3W 17.1N 45.1W 17.9N 48.3W .0N .0W
SHIP 63KTS 74KTS 76KTS 79KTS
DSHP 63KTS 74KTS 76KTS 79KTS

...INITIAL CONDITIONS...
LATCUR = 13.0N LONCUR = 25.3W DIRCUR = 270DEG SPDCUR = 20KT
LATM12 = 13.0N LONM12 = 21.0W DIRM12 = 284DEG SPDM12 = 22KT
LATM24 = 11.4N LONM24 = 17.3W
WNDCUR = 30KT RMAXWD = 40NM WNDM12 = 25KT
CENPRS = 1008MB OUTPRS = 1011MB OUTRAD = 125NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM
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Pay no attention to the ATCF headings, they're often wrong.

Look to the TCGM.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
692. xcool
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690. Skyepony (Mod)
AF301 chucked a dropsonde at the Gulf disturbance too.
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According to the latest coordinates, 96 is moving SW. Any ideas on whether it's going to move in the same direction as Danielle, or is it going to continue to the west later on?
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Danielle to retain hurricane status at 5pm advisory unless later altered.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting Cotillion:
AL, 06, 2010082418, , BEST, 0, 171N, 475W, 65, 990, HU, 64, NEQ, 25, 15, 0, 25, 1011, 240, 20, 0, 0, L, 0, , 0, 0, DANIELLE, D,


Heading of 240?!
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found a very cool youtube video with dr masters.

its an noaa flight into hurricane gilbert

Link
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Well this is one Bermudian that has been paying attention to what Storm & Levi have been saying.
Thank you for all of your efforts.
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12z ECMWF has Danielle going up east of Bermuda and blows her up into a major hurricane.

Also notice Earl weakening south of her due to the upper-level environment being far less than perfect. With Danielle likely to get fairly large, Earl passing by to her south and getting caught up in her skirts would be bad for him until Danielle can get well out of the way.

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000
WHXX01 KWBC 241837
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1837 UTC TUE AUG 24 2010

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE DANIELLE (AL062010) 20100824 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
100824 1800 100825 0600 100825 1800 100826 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 17.1N 47.5W 18.4N 50.5W 19.4N 53.2W 20.2N 55.2W
BAMD 17.1N 47.5W 18.2N 49.6W 19.6N 51.6W 21.0N 53.4W
BAMM 17.1N 47.5W 18.2N 50.2W 19.3N 52.4W 20.3N 53.9W
LBAR 17.1N 47.5W 18.4N 50.2W 19.8N 53.2W 21.1N 56.1W
SHIP 65KTS 60KTS 61KTS 61KTS
DSHP 65KTS 60KTS 61KTS 61KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
100826 1800 100827 1800 100828 1800 100829 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 20.9N 56.5W 24.0N 57.6W 29.6N 60.1W 32.4N 63.1W
BAMD 22.5N 55.2W 25.5N 59.0W 28.4N 62.2W 32.1N 63.0W
BAMM 21.6N 55.2W 25.2N 57.8W 29.5N 61.2W 32.7N 62.6W
LBAR 22.6N 58.6W 26.0N 62.9W 29.7N 63.6W 33.4N 61.7W
SHIP 64KTS 73KTS 87KTS 87KTS
DSHP 64KTS 73KTS 87KTS 87KTS

...INITIAL CONDITIONS...
LATCUR = 17.1N LONCUR = 47.5W DIRCUR = 295DEG SPDCUR = 18KT
LATM12 = 15.7N LONM12 = 44.0W DIRM12 = 281DEG SPDM12 = 16KT
LATM24 = 15.2N LONM24 = 40.7W
WNDCUR = 65KT RMAXWD = 20NM WNDM12 = 85KT
CENPRS = 990MB OUTPRS = 1011MB OUTRAD = 240NM SDEPTH = D
RD34NE = 120NM RD34SE = 90NM RD34SW = 60NM RD34NW = 90NM

$$
NNNN
Member Since: August 23, 2008 Posts: 7 Comments: 5300
AL, 06, 2010082418, , BEST, 0, 171N, 475W, 65, 990, HU, 64, NEQ, 25, 15, 0, 25, 1011, 240, 20, 0, 0, L, 0, , 0, 0, DANIELLE, D,
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Latest vis loop shows CDO reforming..let's see if it holds up
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Quoting StormW:


No way!
Good afternoon StormW...I think my question got ate by the blog....what do you think the chance is for Danielle to keep WNW? Thanks in advance
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ok then the map needs to put the first part of Colins' track lol
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Quoting StormW:


Well, I've always had a theory...Hurricanes do not go to school, and do not care about Calculus, and Differential Equations, and don't read computer model guidance outputs.


I never doubted you Storm. :)
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Quoting Levi32:


ZCZC MIATCPAT1 ALL
TTAA00 KNHC DDHHMM
BULLETIN
HURRICANE DANIELLE ADVISORY NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010
500 AM AST TUE AUG 24 2010

...DANIELLE REACHES CATEGORY TWO STATUS...FAR OUT AT SEA...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...15.9N 44.6W
ABOUT 1110 MI...1790 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/HR
PRESENT MOVEMENT...W OR 280 DEGREES AT 20 MPH...32 KM/HR
MINIMUM CENTRAL PRESSURE...973 MB...28.73 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


oh ok
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671. CJ5
She is getting her act back together. Covering CDO, Convection over the center and outflow becoming more symetrical. Could see another blow up like yesterday afternoon.
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Quoting Engine2:
Loving Storm's sarcasm as he has been taking heat all week for relying on his experience and what he sees in the patterns not just the models!


Thats it though! It's the current pattern that we need to use more then the models. The pattern clearly showed me that Bill was to swipe New England when the models and NHC had it recurving around where Danielle is *forecast* to recurve. I really think the NHC relies more on the models then the pattern. Alex was *forecasted* to hit southern Mexico when the pattern and steering layers showed a WNW to NW movement, putting the borderline of TX/MX more at risk.
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Quoting Hurricanes101:


did any advisory come out that officially made her a CAT 2?


Yes

SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...15.9N 44.6W
ABOUT 1110 MI...1790 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/HR
PRESENT MOVEMENT...W OR 280 DEGREES AT 20 MPH...32 KM/HR
MINIMUM CENTRAL PRESSURE...973 MB...28.73 INCHES

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hey stormw what do you think of the gfs track for 96l think the other models will come west and or south or will recurve be it hits 50
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Quoting markot:
earl will be threat to fl. down the road.....and another disturbance is close to coming off african coast..
any facts to back that up?
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Quoting reedzone:


Welcome to my world...
'


Reedzone said this was going to hit Miami when it came off africa 5-6 days ago. Then again, if we went by him, we would be on the Greek Alphabet by now. :)
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Quoting Hurricanes101:


did any advisory come out that officially made her a CAT 2?


ZCZC MIATCPAT1 ALL
TTAA00 KNHC DDHHMM
BULLETIN
HURRICANE DANIELLE ADVISORY NUMBER 11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010
500 AM AST TUE AUG 24 2010

...DANIELLE REACHES CATEGORY TWO STATUS...FAR OUT AT SEA...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...15.9N 44.6W
ABOUT 1110 MI...1790 KM E OF THE LESSER ANTILLES
MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/HR
PRESENT MOVEMENT...W OR 280 DEGREES AT 20 MPH...32 KM/HR
MINIMUM CENTRAL PRESSURE...973 MB...28.73 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.
Member Since: Posts: Comments:
663. Skyepony (Mod)
AF301 went out in the gulf today too & flew through that in the gulf, 1 pass with the SFMR on. Wind shift there Maybe some 30kt winds..
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Quoting Levi32:


She was a Cat 2 last night but should never have been upgraded in my opinion....but she was between 2 of the advisories.


did any advisory come out that officially made her a CAT 2?
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Quoting Hurricanes101:
WU 2010 tracking map is screwed up

first off, where is the first part of Colins' track?

second, why is there an orange hurricane symbol for Danielle? She has yet to be a Category 2 storm, or did I miss something?


She was a Cat 2 last night but should never have been upgraded in my opinion....but she was between 2 of the advisories.
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Quoting swlavp:
StormW has been saying that all along.


Actually a few of us here has been predicting a more westward motion.. The high is stronger then what the models showed, and allowed the 1st weakness to miss Danielle.
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Quoting StormW:


No way!
Loving Storm's sarcasm as he has been taking heat all week for relying on his experience and what he sees in the patterns not just the models!
Member Since: February 27, 2006 Posts: 0 Comments: 482
Quoting reedzone:


An epic model shift StormW, it all puts Bermuda at a much higher risk.
StormW has been saying that all along.
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WU 2010 tracking map is screwed up

first off, where is the first part of Colins' track?

second, why is there an orange hurricane symbol for Danielle? She has yet to be a Category 2 storm, or did I miss something?
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Quoting Levi32:
Say hi to Danielle's brand new CDO.





CDO is spreading quickly, whatever was messing with the storm core has been ejected.
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Quoting StormW:
Back for a short.


An epic model shift StormW, it all puts Bermuda at a much higher risk.
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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.