Tropical Storm Bertha Model Runs

[Derek Ortt]

Those who were adamantly sticking to an early recurvature are being forced to strongly reconsider their original views at this critical juncture. We are rapidly approaching the stage where it's becoming very tempting to discard the model guidance's solutions shown in the chart (above). Bertha continues to move west; in fact, it is even potentially passing just south of the next TPC forecast position (again). The model "cluster" indicates a current WNW movement and a slightly slower forward speed, when that is clearly not the case.

if it is passing south of the forecast point, it is passing less than a whole 20NM south

[Thunder44]

The 12z Euro has recurvature in five to seven days, east of 70W.

[hiflyer]

looks like getting some better data tomorrow to help the models..but not the Gulfstream

ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK. (AMENDED)
A. POSSIBLE AIR FORCE FLIGHT ON TS BERTHA,
8/18Z, 20N 57W.
3. BEGIN 12 HRLY FIXES 9/12Z IF NECESSARY.

[NDG]

Yeah, right over Bermuda according to ECM's 12z run.

[cycloneye]

12z HWRF recurves around 61w as a hurricane:

http://moe.met.fsu.edu/cgi-bin/hwrftc2. ... =Animation

[Frank2]

Hmmm they start it at 17.8 yet the Dvorak suggests 17.4, thats quite a large difference in terms of intial starting points!

I think they were using the Frank "theory" mentioned earlier...

[cycloneye]

12z GFDL recurves it around 61w as a cat 2 hurricane.

http://moe.met.fsu.edu/cgi-bin/gfdltc2. ... =Animation

[vacanechaser]

Hmmm they start it at 17.8 yet the Dvorak suggests 17.4, thats quite a large difference in terms of intial starting points!

I think they were using the Frank theory mentioned earlier...

lol... gotta give you that one.... lol...



Jesse V. Bass III
http://www.vastormphoto.com
Hurricane Intercept Research Team

[wxmann_91]

most models, except for HWRF have been OUTSTANDING on Bertha

There is no reaosn to totally discount them... unless one does not like what they say

Yeah, I see no reason to discount the models. The East Coast trough in about 4-5 days doesn't lie...it's recurving.

[KWT]

GFDL is very quick to break the ridge down and also has it as a cat 1/2 for a lot of its journey, that probably explains why its so far east in terms of track. Interestingly thats a little close to Bermuda.

[cycloneye]

12z NOGAPS also recurves,this one at 65w to end near Bermuda as a hurricane.

http://moe.met.fsu.edu/cgi-bin/ngptc2.c ... =Animation

[Frank2]

vacanechaser,

Thanks - I was a graduate of the Radar O'Reilly School, Ottumwa, Iowa...

LOL

[KWT]

In some ways a track a little to the west of what some models are showing may not be a bad thing as some of the further easterly models are really close to Bermuda, a track a little further west should keep this over water.

[Aric Dunn]

sorry but the models dont have a very good handle on the initial conditions let alone 3 to 4 days down the road..

they are flaping in the wind right now..

[Aric Dunn]

the 18z bamm and bamd both show a west turn thats a first for both of them... maybe a sign of things to come..

so thats now the gfs, bamm,bamd,ukmet,cmc showing a west turn

[Frank2]

Well, they are all definetly better clustered (for a recurve) in those last two runs...

I would discount the westward jogs - they look spurious to me...

[Aric Dunn]

Well, they are definetly better clustered (for a recurve) in those last two runs...

yeah but now half are turning west and the others are still north.. so the disagreement is getting worse again..

[KWT]

There is two groups thats clear, the GFS, UKMO and CMC take this off towards the USA whilst the ECM and the other two main high resolution models take it to the NW/N towards the end of the run.

Lest us forget that the easterly track models take this damn close to Bermuda...

[cycloneye]

Those models that recurve have a hurricane (GFDL a cat 2) and those models that not recurve have a weaker Bertha.

[KWT]

Yep that seems to be the case, I think that something down the middle is seemingly the most likely option out there, I think the GFDL is recurving too quickly but the others probably are too far south and weak with Bertha. I think it will get to 32N by 67W IMO.