Will we continue to be protected under this trough

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robbielyn
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Re: Will we continue to be protected under this trough

#21 Postby robbielyn » Fri Jul 27, 2007 4:28 pm

So if these troughs arent as strong as 2006 and intermittent, and wont necessarily prevent landfalls the problem is these troughs carry such high sheer so nothing will form or stay together as long as we have sheer.
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Re: Will we continue to be protected under this trough

#22 Postby Opal storm » Fri Jul 27, 2007 4:33 pm

With a good 2 1/2 months of the most active period of the season ahead of us, I'm not putting all my faith into the cold fronts protecting my area. It all depends on the timing between the front and the storm.
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Re: Will we continue to be protected under this trough

#23 Postby robbielyn » Fri Jul 27, 2007 4:58 pm

yeah well these troughs are more than weekly it seems. The low in the western gulf is being sheered by a trough over california so I really think we are going to be in relative good shape. we have low sst's in the atlantic with the saharan dust blocking the sun from warming up the waters, we have neutral conditions and we have sheer. I am not saying we are home free, we should all be prepared anyways, but I wouldn't be surprised if we have an average season. We'll see still early yet. where is that bermuda high?
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Re: Will we continue to be protected under this trough

#24 Postby Extremeweatherguy » Fri Jul 27, 2007 6:16 pm

robbielyn wrote:yeah well these troughs are more than weekly it seems. The low in the western gulf is being sheered by a trough over california so I really think we are going to be in relative good shape. we have low sst's in the atlantic with the saharan dust blocking the sun from warming up the waters, we have neutral conditions and we have sheer. I am not saying we are home free, we should all be prepared anyways, but I wouldn't be surprised if we have an average season. We'll see still early yet. where is that bermuda high?
Sure, there are low SSTs in parts of the Atlantic..but in the places it matters most (GOM, Caribbean, etc) they are not low at all! In fact, many areas are seeing above normal SSTs there. Also, the SAL has been diminishing over the past week or so, and the "saharan dust" is likely not going to be that big of a deal (compared to normal) during the peak of the season. Also, these troughs are not as constant as you are implying. They are transient and will become more so in August. Latest models, suggest that the bermuda high may even try to build westward in the coming weeks..but even if it does not, the troughs (since they are not as sharp as '06) will only be able to recurve storms north of 25N. Any storms coming through the caribbean will likely not be turned out to sea and could be a threat to the GOM and SE United States. IMO, It is still too early to say that we will be in "good shape" this season.

Current wind shear: http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8sht.html

SSTs: http://www.aoml.noaa.gov/phod/dataphod1/work/HHP/NEW/2007207atsst.png

18z GFS showing high pressure building in...

Day 7: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/fp1_168.shtml

Day 10: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/fp1_240.shtml

Day 13: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/18/fp1_312.shtml
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Re: Will we continue to be protected under this trough

#25 Postby storms in NC » Fri Jul 27, 2007 6:18 pm

[quote="robbielyn"]yeah well these troughs are more than weekly it seems. The low in the western gulf is being sheered by a trough over california so I really think we are going to be in relative good shape. we have low sst's in the atlantic with the saharan dust blocking the sun from warming up the waters, we have neutral conditions and we have sheer. I am not saying we are home free, we should all be prepared anyways, but I wouldn't be surprised if we have an average season. We'll see still early yet. where is that bermuda high?[/quote]

Gone for a run be back later :D
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#26 Postby Steve » Fri Jul 27, 2007 6:29 pm

>>So if these troughs arent as strong as 2006 and intermittent, and wont necessarily prevent landfalls the problem is these troughs carry such high sheer so nothing will form or stay together as long as we have sheer.

No way. It's July. July is usually one of the tropical months where the basin has the most shear (with an a, the double e's are for see-through curtains/pantyhose, etc. :) ). Also, shear can build up a system as much as it can tear one apart. It depends on the position of a tropical system relative to the shear. That's something I learned on Bastardi's videos back in the late 90's or in 2000. You have to section off the setup into quadrants - two of which are sinking air and would serve to be hostile to development while the other two provide lift for the storm and help ventilate it. You can see the effects directly in June and usually in October systems (and specifically in the hybrids).

And even hostile shear doesn't always ring the death knell. Look back at TD #10/TD 12 in 2005 which became Hurricane Katrina. Apparently the old cliche' that what doesn't kill you will make you stronger either was demonstrated or the energy that was to become Katrina was as determined as it could be.

Steve
Last edited by Steve on Fri Jul 27, 2007 6:47 pm, edited 1 time in total.
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#27 Postby Steve » Fri Jul 27, 2007 6:46 pm

>>Just look at that thing dipping all the way doen to N FL..Thats Autumn like!

It is my completely unprofessional opinion as stated last week when Louisiana got a cold front which behind it we finally got back into the 90's and clear skies for a couple of days, that it would take another front or two to come through to complete the pattern change into a summer pattern. It's rained almost every day here in July, and it's not been the typical seabreeze fronts coming in off the Gulf between 10-11am followed by heat and then PM storms. It's mostly been upper boundaries settling in and sticking around providing a triggering mechanism for rain and thunderstorms. So my opinion is that there had to be a few more troughs actually coming through in order for high pressure behind them to begin to build in and eventually merge with the Bermuda High. It's going to happen, and depending on how strong the ridge gets, it could be a repeating pattern, a pulsing pattern or one occasionally interrupted by troughs wherein the pattern alternates between having an open Gulf Coast and open East Coast. We're just going to have to wait to see what happens from mid-August through late September.

Also, it should be noted that the SOI daily returned to positive over the last couple of weeks after being strongly negative. The downstream implications tend to follow 15+/- days for the eastern North America.

http://www.longpaddock.qld.gov.au/Seaso ... SOIValues/

Further, some of the deep waters in the Caribbean and parts of the Gulf of Mexico have more heat content than they did in 2005. And once some of this rain lets up and the rivers are done emptying it out, the waters along the cooler, immediate coasts are going to warm up.

I'm not particularly liking the setup for the southeast.

Some people like to draw parallels to other years based on only one or two factors and then end up calling it an analog. That doesn't work. Every year is different, and every year has different influencing factors. In the absence of a strong El Nino/La Nina, we have to go elsewhere to see what the major factors that affect our hurricane season are (be they the NAO, SST's, African Dust, waves moving too fast, etc.), and we won't really know what the biggest factors were until we look back on the season.

Again, we've got a long way to go. No temporary or transient pattern in the Western Atlantic today is going to mean anything come August or September. And furthermore, the only thing that an east coast trough even plays on are systems that form out in the Atlantic. It doesn't affect some home-spun systems or tropical waves that happen to be crusiing underneath.

Steve
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