The tropics are quiet

By: Dr. Jeff Masters , 1:11 PM GMT on September 06, 2009

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Considering that this is historically the peak week of the Atlantic hurricane season, the tropics are quiet. There is an area of disturbed weather in the middle Atlantic (95L) that NHC has been mentioning in their Tropical Weather Outlook the past day, but this disturbance is entering a region of high wind shear and is not a threat to develop.

A strong tropical wave with plenty of rotation is emerging off the coast of Africa this morning, and this wave is a good candidate to show some development this week as it heads west-northwest over the Atlantic. The wave is under about 15 knots of wind shear, and is being developed by several models, including the GFS and ECMWF. However, the models show that this new wave will be pulled northwestward by a strong trough of low pressure this week, and it appears unlikely that the wave will make the long crossing of the Atlantic necessary to threaten any land areas. Another wave with plenty of spin will emerge from the coast of Africa two days from now, and will also have a chance to develop.


Figure 1. Morning satellite image of 95L and a new tropical wave with potential to develop, emerging from the coast of Africa.

An area of concentrated thunderstorms has developed off the North Carolina coast in association with the remains of an old cold front. This system is under about 20 - 30 knots of shear, and is not tropical. However, it will bring heavy rain just offshore of North Carolina's Outer Banks today as it slides north-northeastward along the coast.

I'll have an update Monday.

Jeff Masters

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Yes, tennis at the Open is amazing...Africa also very interesting! Soggy day in the Outer Banks. have a good one everyone!
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Quoting Weather456:
The models show an upper trough digging across the Eastern United States and secluding offshore the SE USA, that is the where the surface low develops and deepens. This setup up is highly subtropical or non tropical similar to 90L this year and Andrea 2007, among others.
correct, somewhat like Danny 09' and Andrea 07' and you stated.
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The models show an upper trough digging across the Eastern United States and secluding offshore the SE USA, that is the where the surface low develops and deepens (probably with the help of some other triggers). This setup up is highly subtropical or non tropical similar to 90L this year and Andrea 2007, among others.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
can someone give me a good link to see the GOM and Atlantic ocean for satelite the one on WU is really full of interfearance and is all jumpy today so I cant really look at it. Thanks in advance
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06z GFS takes the wave emerging of of Africa, moving W, then NW, and then N.
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Quoting Ameister12:
I guess September won't be that quiet from what I'm seeing on the models.


huh? from what I am hearing,there isn't much to worry about.
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BBL
Thank You 456 for you input on things this morning.... You all have a great day

Taco :0)
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The African wave just coming off the coast is a beauty.

... it appears unlikely that the wave will make the long crossing of the Atlantic necessary to threaten any land areas. JM
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Quoting extreme236:
When I see the ECMWF developing something I pay attention to it, since its been very accurate this season.
correct, I do the same.
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Enjoy the rest of the Labor Day Weekend in the US Folks...Good sports on through tommorow and time to watch some more tennis and football..... :)
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Wow just looked at some maps around the gomex and man things are just hostile in most locations.

Nice to see during peak.
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Good morning,
The feature parallel to the coast of the Carolinas, seems to be a trough that left behind a LLC and thus the GFS forms it. The hurricane in the central Atlantic seems to be the wave emerging off the coast of Africa.
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A recurvature will most likely happen with this new African wave emerging given that I expect it will strengthen quickly given the current conditions and shear staying to north because of the anticyclone over it, which is very impressive and protecting it from any effects of shear. Given the potential strength of this disturbance already a recurvature is most likely as it is deeper.
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Quoting TheDawnAwakening:
... Gulf of Mexico has too much wind shear for anything to develop. So the two favorite areas right now for development remain with the wave emerging off the African west coast and the disturbance off the SC coastline.

ShearMap
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Tropical depression may form this week

Elsewhere in the tropics
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Cyclone phase diagrams indicate the feature offshore the SE USA will be non tropical. the CMC has the feature become warm-core but only after it retrograde back over land due to high pressure

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Maybe something hybrid....Blah
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Quoting hurricane23:


In terms of any impacts on the U.S. i see none and trust me ive viewed the models BUT as stated without much ridgeing in place look for things to stay out to sea.The GFS in particular seems to be spinning up that wave with a recurve around 40-45w.


I wasn't referring to a US threat, that appears very unlikely with this new wave. I was just referring to development.
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Great 850 MB vort with African Wave.


Impressive Anti-Cyclone with the African Wave.


Good Organization


Little SAL, most to the North.


Model Support by quite a few models including the ECMWF and the GFS.
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Quoting AussieStorm:

An area of concentrated thunderstorms has developed off the North Carolina coast in association with the remains of an old cold front. This system is under about 20 - 30 knots of shear, and is not tropical. However, it will bring heavy rain just offshore of North Carolina's Outer Banks today as it slides north-northeastward along the coast.

Jeff Masters



Ooops, I didn't realize Dr. Masters posted a new blog.
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When I see the ECMWF developing something I pay attention to it, since its been very accurate this season.
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Quoting extreme236:


Guess your missing all those models developing that new wave then?


In terms of any impacts on the U.S. i see none and trust me ive viewed the models BUT as stated without much ridgeing in place look for things to stay out to sea.The GFS in particular seems to be spinning up that wave with a recurve around 40-45w.
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There is a low level circulation developing seen on 850mb vorticity charts as well as visible satellite imagery. Mid level rotation is a little in the 500mb level, but it is increasing. Wind shear is still around 20 to 30 knots, but it is decreasing nonetheless. Well this shear axis is to the north of the developing low level circulation. Both low and mid level developing circulations appear to be stacked well. Shear over the disturbance is roughly 15-20 knots and is decreasing. Thunderstorm activity is strong and roughly mainly north of the developing circulation with some storms over the low. This looks extratropical right now, but if it can remain roughly stationary then conditions look to become more favorable with especially favorable SSTs as it sits over the Gulf Stream. Gulf of Mexico has too much wind shear for anything to develop. So the two favorite areas right now for development remain with the wave emerging off the African west coast and the disturbance off the SC coastline.
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Quoting hurricane23:


Possible low developing up near SC but does not look tropical to me.

An area of concentrated thunderstorms has developed off the North Carolina coast in association with the remains of an old cold front. This system is under about 20 - 30 knots of shear, and is not tropical. However, it will bring heavy rain just offshore of North Carolina's Outer Banks today as it slides north-northeastward along the coast.

Jeff Masters
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Quoting extreme236:


Guess your missing all those models developing that new wave then?


Apparently, but its not like 23 to forget that.
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Quoting Chicklit:
So nothing is happening nor is forecast to happen, correct?
CaribLoop
GOMexLoop


gomex under high shear, there are numbers and a little vort on a feature near coastal central mex but....



nothing too alarming
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Quoting kimSCbeaches:
Ahhhh... What is going on off the SC coast????


good question
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Quoting Weather456:


I was about to post it. The ridge stationed over the NE USA/NW Atlantic. That blocking pattern would be ideal for subtropical cyclogensis.

NWAtlLoop
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Quoting kimSCbeaches:
Ahhhh... What is going on off the SC coast????


Possible low developing up near SC but does not look tropical to me.
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Quoting hurricane23:
With very little ridgeing and unfavorable upper conditions across the most of the eastern tropcial atl iam really not expecting much in the way of development anytime soon.

This quiet period during peak is much welcomed on my end.

adrian


Guess your missing all those models developing that new wave then?
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Good Morning....As much as I enjoy tracking tropical storms and this Blog for the past four seasons, and as Dr. M. has noted, reality is starting to set in during the peak of this season. Looks like the forecasts for a normal to below normal season due to Enso conditions and the like is coming to pass. That might seem "boring/bust" to some but is really a blessing for those who live in the areas affected by the Season. Also wondering if we might be seeing the close of the active multi-decadal cycle and a gradual shift to a less active phase.....We'll have to see what happens over the next 2-3 seasons in terms of overall activity..........WW
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Quoting TampaSpin:
If anyone needs current graphics my web stays current 24-7

-Great site, Tampa! thanks for the link.
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Quoting serialteg:
The wave in the middle of the Atl reaching low shear finally

CatlLoop
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definitely getting more breezy here in southeast NC
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Ahhhh... What is going on off the SC coast????
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Quoting BurnedAfterPosting:


What really catches my eye though is the ridge, it looks like it holds for now


I was about to post it. The ridge stationed over the NE USA/NW Atlantic. That blocking pattern would be ideal for subtropical cyclogensis.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
With very little ridgeing and unfavorable upper conditions across the most of the eastern tropcial atl iam really not expecting much in the way of development anytime soon.

This quiet period during peak is much welcomed on my end.

adrian
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So nothing is happening nor is forecast to happen, correct?
CaribLoop
GOMexLoop
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The wave in the middle of the Atl reaching low shear finally
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Quoting Weather456:
Now the ECMWF is showing a low pressure area developing along the outerbanks in 120 hrs, around the same time frame as the GFS/GFDL merge but the source of genesis comes from the current stalled out feature. That feature moves NE and becomes extratropical.



it also shows an elongated area of vorticity, likely a dying front or very long surface trough, extending from the extratropical feature above, with the tail end condolencing offshore Texas in 1 week.



What really catches my eye though is the ridge, it looks like it holds for now
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Glad the weather is not spoiling the Golf... looking forward to watching Mike Weir win today :)


AOI

AOI

AOI

AOI
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Quoting AussieStorm:

It wont stop the loonies from coming in and causing a stir.






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Good Morning. I hope everyone is enjoying the weekend. Watching a lot of great tennis with the U.S. Open!

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I guess September won't be that quiet from what I'm seeing on the models.
Member Since: August 9, 2009 Posts: 10 Comments: 5026
The CMC also shows a similar feature

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Now the ECMWF is showing a low pressure area developing along the outerbanks in 120 hrs, around the same time frame as the GFS/GFDL merge but the source of genesis comes from the current stalled out feature. That feature moves NE and becomes extratropical.



it also shows an elongated area of vorticity, likely a dying front or very long surface trough, extending from the extratropical feature above, with the tail end condolencing offshore Texas in 1 week.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Michfan:
Now the boredom settles in. TBH the blog needs it after the past week.

It wont stop the loonies from coming in and causing a stir.
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Now the boredom settles in. TBH the blog needs it after the past week.
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Quoting Weather456:
The GFS/GFDL merge is showing that a surface trough develops over the SE GOM and tracks across Florida and along the US East Coast, deepens it rather significantly offshore SC. It also shows Fred in the Eastern Atlantic


Looks like Fred and Grace.
Member Since: August 9, 2009 Posts: 10 Comments: 5026
The GFS/GFDL merge is showing that a surface trough develops over the SE GOM and tracks across Florida and along the US East Coast, deepens it rather significantly offshore SC. It also shows Fred in the Eastern Atlantic

Member Since: July 24, 2005 Posts: 407 Comments: 19076

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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.