ATL: Ex COLIN - Discussion
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Re: ATL : Tropical Depression Four - DISCUSSION
Probably dumb question, How reliable are the forecast of the bermuda high??? The reason i ask this is,they are forecasting td4 to find a weakness and go more nw. I remember Frances and Jeanne were blocked by the high. Thanks for any info. Mel
Last edited by mel38 on Mon Aug 02, 2010 6:13 pm, edited 1 time in total.
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Re: ATL : Tropical Depression Four - DISCUSSION
tolakram wrote:Gladstone wrote:ColinDelia wrote:What is a "5-WAVE PROGRESSIVE PATTERN"?
I believe the 5-Wave Pattern being referenced is the Polar Vortex. This vortex can take only one of two forms, either a 3-Wave or a 5-Wave pattern. Each 'wave' is a lobe on the vortex.
The best way to view this is from the North Pole:
http://raleighwx.easternuswx.com/models ... TNH120.gif
(Hello everyone!)
Thanks for the info gladstone, and welcome!
Thank you tolakram. And I should add that another poster here was correct in noting the 3-Wave pattern produces deeper troughs (something you may want to keep an eye on as winter approaches!)
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Convection is pretty good right now, still holding the ball look but if anything the center looks right on the eastern sidem thats the classic sign of a SAL surge occuring and easterly shear possibly occuring...this system may well end up heading westwards further then expected right now but we will see!
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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products
Re: ATL : Tropical Depression Four - DISCUSSION
Looks a little west but could be a satellite illusion.
What is that big swipe of shear pushing off the NE quadrant in a pointed shape? The Ridge?
What is that big swipe of shear pushing off the NE quadrant in a pointed shape? The Ridge?
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Whats pretty interesting is if anything the latest convective burst is a little WSW of the previous one, thats not what you'd expect with a system that is progged to head WNW, at least unless its starting to get sheared...
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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products
Re: ATL : Tropical Depression Four - DISCUSSION
It looks slightly better than a few hours ago, but it still is probably just below TS strength. It looks like it is undergoing some easterly shear...it appears the center of circulation is east of the convection, which doesn't surprise me given the speed it is going. If it doesn't slow down, it will have a difficult time getting going, and will be very vulnerable when the TUTT becomes a factor.
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- wxman57
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Re: ATL : Tropical Depression Four - DISCUSSION
Don't try to estimate movement by looking at the convective blob, as it's not the center. The center is east of the convection and is not necessarily moving in the exact same direction or at the same speed. And don't judge intensity based upon that convective blob. The current convection appears to be outrunning the LLC (if there is an LLC). I had been measuring a movement of that blob of storms toward 282 degrees at close to 20 kts this morning. Currently, I'm estimating a 6-hr LLC movement toward 275-280 deg at close to 15 kts of the weak LLC.
It's nowhere near a TS, and there may be questions as to whether it even has an LLC. Low-level easterly flow appears to have increased, knocking convection west of any LLC. Models indicate it will remain on the western side of any upper-level anticyclone, in moderate shear. The big debate in the office today was whether it would even survive past 48-72 hrs. My vote was for yes (would survive), as I just don't trust model shear forecasts as far as I can throw them. But I don't know it'll get as strong as the NHC is forecasting. Too many negatives appear to be in its path. Good news for the NE Caribbean Islands.
Long-term, can't rule out an East U.S. Coast threat, but I'm not too worried for them yet. This does not have the markings of a big and dangerous hurricane. More like a sheared moderate TS.
It's nowhere near a TS, and there may be questions as to whether it even has an LLC. Low-level easterly flow appears to have increased, knocking convection west of any LLC. Models indicate it will remain on the western side of any upper-level anticyclone, in moderate shear. The big debate in the office today was whether it would even survive past 48-72 hrs. My vote was for yes (would survive), as I just don't trust model shear forecasts as far as I can throw them. But I don't know it'll get as strong as the NHC is forecasting. Too many negatives appear to be in its path. Good news for the NE Caribbean Islands.
Long-term, can't rule out an East U.S. Coast threat, but I'm not too worried for them yet. This does not have the markings of a big and dangerous hurricane. More like a sheared moderate TS.
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Classic SAL set-up Wxman57, looking at the images even on IR its pretty obvious that its now in the SAL region. Easterly shear with the mid levels streaming ahead faster is a trademark SAL signature and even though the worst of it is to the north right now the shear is still hitting it.
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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products
THE CURRENT 5-WAVE PROGRESSIVE PATTERN
Don't have GARP like wxman57, but will draw trough axes on 500-mb analysis at 12Z.

Don't have GARP like wxman57, but will draw trough axes on 500-mb analysis at 12Z.

Last edited by supercane on Mon Aug 02, 2010 6:44 pm, edited 1 time in total.
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- ConvergenceZone
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Re:
KWT wrote:Models really do seem quite suggestive of this system recurving and we are starting to get to the time where recurving becomes increasingly likely.
The system is looking pretty good now though, the NHC may well be tempted to upgrade this one, but doesn't look like its going to have a long shelf-life!
I agree KWT, once the TULL gets a hold of this storm, its going to rip it to shreds, and it's not going to take much to rip it apart either, since it's only going
to be a tropical storm.
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If the center is right on the eastern edge of the convection like it is suspected to be then the NHC will probably not upgrade yet, the Dvorak agencies are pretty close to 35kts though...
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Re: ATL : Tropical Depression Four - DISCUSSION
Gladstone wrote:This vortex can take only one of two forms, either a 3-Wave or a 5-Wave pattern. Each 'wave' is a lobe on the vortex.
Not quite right. From http://weatherfaqs.org.uk/node/145:
These long-waves are key elements in the atmospheric circulation, and can be traced well into the stratosphere. At any one time, there are between 3 and 7 such waves, the number in any particular latitude band dependent upon a fine balance between the speed of the airflow through the trough/ridge system and the wavelength.
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- ConvergenceZone
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Re:
rreedbug3 wrote:Looks like a TS to me. I bet this will go on to become a hurricane down the road... A big season for hurricanes this one is!
What's your reasoning to think this will be a hurricane? I haven't heard one forecaster even remotely predict this based upon the conditions its heading into....I would be absolutely shocked if this became a hurricane. the conditions don't exist, nor will they exist(if you look at the maps) to support a hurricane. Only a drastic change in the path into to the carib would give in a shot down the road, but even then it will encounter some shear along the way.
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Re: Re:
ConvergenceZone wrote:
I agree KWT, once the TULL gets a hold of this storm, its going to rip it to shreds, and it's not going to take much to rip it apart either, since it's only going
to be a tropical storm.
Indeed and if it doesn't make TS status in the next 24hrs conditions only get worse downstream so it may struggle to get there but still time for that to occur. I do think easterly shear is occuring right now.
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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products
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Re: Re:
ConvergenceZone wrote:rreedbug3 wrote:Looks like a TS to me. I bet this will go on to become a hurricane down the road... A big season for hurricanes this one is!
What's your reasoning to think this will be a hurricane? I haven't heard one forecaster even remotely predict this based upon the conditions its heading into....I would be absolutely shocked if this became a hurricane. the conditions don't exist, nor will they exist(if you look at the maps) to support a hurricane. Only a drastic change in the path into to the carib would give in a shot down the road, but even then it will encounter some shear along the way.
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