Random Chaos
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It really depends on the model as to how far west it will be pushed. (7/5, 06 run) is showing that it will recurve on the western edge of the high in about a week, keeping it out to sea. In comparison, (7/5, 00 run) is keeping the high stronger and further west, taking the storm on a track toward Cuba.
This time period is too far out for accurate forecasts though. When you have two of the major models used for global weather forecasting showing completely opposing solutions at that time range, you can pretty much toss both out and say we have no clue what will happen.
About all that I can tell from the models right now is that Bertha is going to maintain Tropical Storm status for the next few days until it hits more favorable solutions, and then possibly intensify.
I think all of us here on the east coast hope the high pressure ridge weakens, as the calls for.
References:
http://moe.met.fsu.edu/tcgengifs/
http://euler.atmos.colostate.edu/~vigh/guidance/
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typhoon_tip
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For those interested...I have placed a discussion over in the Forecast Lounge regarding the destiny of Bertha, and whether or not there is any threat to the U.S.. Naturally, it is too early to assess that with any confidence/accuracy, but...there are some early thoughts and views that may interest a few of you.
John
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hurricaneguy
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The 18Z models are showing the ridge breaking down again and Bertha turning out to sea around Bermuda. I still think the only land area in danger will be Bermuda.
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typhoon_tip
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The 18Z models are showing the ridge breaking down again and Bertha turning out to sea around Bermuda. I still think the only land area in danger will be Bermuda.
I wouldn't bite to hard into any given 18Z model solution. That, and the 06Z for that matter, are the coarser model runs of the 24 hour cycle. 00Z and 12Z have finer resolution and therefore, superior data ingests. Treat the 18Z runs as just another ensemble member.
John
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weatherguy08
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I did notice that the 00Z BAMS, BAMM, and BAMD models now forecast Bertha to go north of the track. Maybe now that the as well as some of the intensity models are showing Bertha strengthening more than previously anticipated, she will feel that northward pull a little more. The evening forecast from the should/could be interesting.
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scottsvb
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Dont buy into the tropical model runs of the BAMM,LBAR etc......Usually the ,GFS ,ECMWF and Ukmet are the Global Models to follow..with somewhat the . I dont usually give much credit to the . Next 36-48hrs will be important on how far N it will be when the trough tries to interact with Bertha. I agree with the on a stronger system would push her more WNW then NNW when she feels the trough. Or if she stays weaker..she will move more WNW.....until the next weakness moves out into the NW Atlantic. We will have a better idea on Monday.
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danielw
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Three areas to watch in the Central Atlantic:
Tropical Storm Bertha-moving west at 22 mph
New Tropical Wave to the SE of Bertha
Large Heavy Thunderstorm complex NE of the Turks and Caicos Islands.
Or wide angle available here:
Wide Angle Rainbow Enhancement
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craigm
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What is going on at Accu weather? This seems a bit irresponsible, if you ask me, judging from the trends in the models and the time frame we are talking about. Click on the the weather video you won't believe it!
http://hurricane.accuweather.com/hurrica...&stormNum=1
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WeatherNut
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They have been saying for a couple of days now that there should be more of a western component to the track. The models right now are very low confidence. I think it is a bit brazen to show it making a beeline for the Carolina coast though
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Born into Cleo (64)...been stuck on em ever since
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scottsvb
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Well its premature to even speculate a path more than 5 days out. Although the path seems reasonable, he did say things can change. The whole path has todo with the strength of the system and especially if the trough coming off the east coast in a few days picks Bertha up or not... and even if it doesn't will she move west or just meander until the next trough comes early next week. Too much speculation, for now..
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LDH892
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As for Bertha, out past 5 days is still too hard to pin-point with high confidence as others have stated. Looks like surfers along the East Coast may have some better swells/waves next weekend... 
Edited by Ed Dunham (Sun Jul 06 2008 11:33 PM)
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Hugh
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Certainly it is impossible to reliably say more than 5 days out whether Bertha will strike the Carolinas - or anywhere else for that matter. The Accuweather forecast, in terms of projected track, doesn't come as a shock to me, but the speed is too fast, when I look at the model outputs and the forecast.
I expected more of a poleward motion to have begun over the weekend, but it hasn't, so I'm not sold on the storm getting caught up in the trough just yet.
Edit: I just looked back at the advisory archives. In the initial 5-day forecast, the 72HR line read:
72HR VT 06/0600Z 17.5N 40.0W 45 KT
at 06/1500z, Bertha's actual location was 17.4 N...45.1 W. 45 KT
So I guess as far as poleward motion, it's on target based upon the 72 hour forecast, but it's 300nm west of the projected location. Did I do that math right?
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Hugh
Eloise (1975) - Elena and several other near misses (1985) - Erin & Opal (1995) - Ivan (2004)
Edited by Hugh (Sun Jul 06 2008 03:49 PM)
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Genesis
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I dunno....
When I look at the solution it is predicated on the ridge breaking down and the high retrograding NE by several hundred miles.
I find the 's solution rather interesting too - but not persuasive. It keys on a couple of VERY strong impulses north of the Canadian border that allow the ridge to buckle northward and while it takes Bertha almost to the Bahamas before it turns her, it then takes her poleward from there.
NoGaps has an even odder solution, with a massive high coming off the eastern seaboard, basically "pincing" Bertha between the Bermuda high and it, forcing it northward. But that one I buy - if the high shows up in 4-5 days and intensifies as it predicts.
The Wv loop gives some cred to this latter view - but IMHO the movement is too fast. And that, ultimately looks to be the key - if the connection is missed and the trough exits before Bertha gets where it can be influenced, the ridge will rebuild behind that and block polward movement.
So the slower and weaker she is, the more likely she remains westward-bound. Strength and especially speed likely gets her into the connection zone where she can be sucked into the gap as the ridge breaks, and out she'll go.
This far out I wouldn't even attach a probability on an impact on the , although were I in Bermuda I'd be a lot more nervous than being on the East Coast!
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craigm
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Am I seeing things or is this the begining of eyewall formation? A clear microwave pass would help. I think Bertha is approaching Hurricane strength sooner than later just from they way she looks. Outflow is really starting to improve.
http://www.ssd.noaa.gov/goes/flt/t1/loop-rgb.html
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Hugh
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I've been looking at all of the imagery options on SSD... what does pure white on the scale mean in terms of intensity? Not good, I think 
I believe we'll see a Cane tonight, and I'm afraid a much powerful Bertha in on the horizon, if the current satellite is any indication.
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Hugh
Eloise (1975) - Elena and several other near misses (1985) - Erin & Opal (1995) - Ivan (2004)
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weatherguy08
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When you overlay the forecast points onto the satellite loop on the link posted in the post before this one, it looks like Bertha is farther north than the original forecast. We could see even more of a northward shift in the next forecast. Still too early to say if the U.S. is under the gun or not, but it seems like it has becoming less and less likely with the recent models and forecasts from the . I did notice however that the 18Z run of the BAMS has moved south of the forecast as opposed to its earlier position, which may actually indicate that the model has no idea where it's going. In other words, I think the BAMS has been a little inconsistent.
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Random Chaos
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Actually, Hugh, I don't think pure white in and of itself means all that much besides it has quite cold cloud tops. What we need to look for is how curved the imagery is.
Looking at the latest SSD imagery, looks like it's got a part spiral coming off it, placing it somewhere between 2.5 and 3.5 on the scale. Officially, the last call listed on SSD is 3.0, so it really hasn't intensified (as far as SSD is listing), it's just gotten colder (which could be an indication of intensification in progress, but it is not in and of itself an indication of higher intensity).
See for visual reference: http://web.archive.org/web/2005090620254..._guide_to_d.htm
For others:
SSD imagery: http://www.ssd.noaa.gov/PS/TROP/float1.html
SSD intensity (Dvorak numbers): http://www.ssd.noaa.gov/PS/TROP/positions.html
Enjoy!
I'm hoping Bertha goes spinning fish.
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Random Chaos
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Craig, we've got a microwave pass. Not liking what I am seeing.
SSMIS Microwave Pass (1950z, or 3:50pm EDT).
Definite eye defined in the internal storm structure.
Compare to the TMI overpass 3 hours earlier, which was only just starting to show signs of central formation.
(All images via )
[Edit: Fixing bad link]
Edited by Random Chaos (Sun Jul 06 2008 05:04 PM)
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cieldumort
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As noted in the 5PM Discussion, Bertha is intensifying, but currently the MLC and LLC are slightly disjointed. This can be made out in this 1958UTC AMSU Composite 
One can also discern the development of an eye, still in its formative stage.
Given that at this time no appreciable increase in wind shear is on the near-term horizon, and only increases of SST are likely in Bertha's path over the next several days, with this incipient eye, improving co-location of both the MLC and LLC, improving outflow, and more, the forecast calling for Bertha to become our first hurricane of the season looks pretty locked - and quite possibly our first major hurricane (which is not yet the official forecast, but which is entirely within the realm of the plausible, given all outlined above).
The stronger she gets, the more likely she is to respond to any upcoming weakness(es) in the ridge.
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Hugh
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Even though the official forecast does not call for Bertha to become a major came within 5 days, I'd be surprised, given the current trend, if that doesn't happen. As far as responding to weaknesses in the ridge, the more I look at some models, the less I understand... because I don't see the weaknesses in the ridge, at least not within the forecast time period (5 days out).
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Hugh
Eloise (1975) - Elena and several other near misses (1985) - Erin & Opal (1995) - Ivan (2004)
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