Hurricane Helene,Analysis,Sat Pics,Models Thread

[ronjon]

SkeetoBite Graphic of Models

What is LBAR track thinking?

Luis, it's very similar to the 12Z run of NOGAPs.

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

[Lowpressure]

Model spreads are getting worse. Not so sure the ridge will develop the weakness to the degree first thought. Even some signs of the second(Tues) trough not being as strong now. Cycloneye, I would watch this with a careful eye, something strange here with so many things going on and Gordo nearly stationary. I still say some nw followed by a flattening out to the wnw for a while.

[Evil Jeremy]

3 posts in a row from diffrent people stating basicially the same thing! dont see that every day here!

[trugunz]

[WeatherTracker]

when does the nhc expect this system to turn to the nw?

[HurricaneHunter914]

I don't even think the NHC knows where Helene is going now.

[SouthFloridawx]

Maybe Bermuda should pay attention to this one afterall.

http://cimss.ssec.wisc.edu/tropic/real- ... 8dlm2.html

[Praxus]

Wow look how long 1938 maintained hurricane and tropical storm winds overland...assuming that's accurate.

edit - no wonder, that's the famous 'long island express' storm, worst hurricane ever to hit the northeast -

http://en.wikipedia.org/wiki/New_Englan ... ne_of_1938

[WeatherTracker]

SkeetoBite Graphic of Models

What is LBAR track thinking?

Luis, it's very similar to the 12Z run of NOGAPs.

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

isnt the LBAR the most inaccurate model?

[hcane27]

Actually ... for Helene so far the LBAR is off by an average of 96 miles ... but most of that comes at the 72 hr time frame .... the NGPS is off by an average of 94 miles ... compared with the GFDL which has been off an average of 101 miles and the UKMET which has been off by an average of 106 miles .....

[Evil Jeremy]

SkeetoBite Graphic of Models

What is LBAR track thinking?

Luis, it's very similar to the 12Z run of NOGAPs.

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

isnt the LBAR the most inaccurate model?

with Helene, yea. overall, its so-so.

[skufful]

SkeetoBite Graphic of Models

What is LBAR track thinking?

Luis, it's very similar to the 12Z run of NOGAPs.

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

Allright, somebody help me here. Why does this model keep Helene West, or even south of West? The high seems to dissapate above it. What are the "synoptics?"

[pgoss11]

Good question- any pro mets have an answer or what the model might be seeing?

[SouthFloridawx]

LBAR - A Nested Barotropic Hurricane Track Forecast Model

LBAR is a dynamical track prediction model. LBAR is the NHC's implementation of the GFDL VICBAR model. (VICBAR stands for Vic Ooyama's Barotropic model.) The model is initialized with deep layer mean winds and geopotential heights from a mass-weighted average of the 850, 700, 500, 400, 300 and 200 mb levels. Analyses are produced on three nested grids: (1) a fixed synoptic domain 27.5 S to 67.5 N, 10 E to 140 W; (2) a storm environment 50 degree latitude-longitude box centered on the current storm location; and (3) a vortex domain circle of 7.4 degree (about 800 km) radius centered on the current storm location. Domain_Map

The synoptic scale analysis is obtained directly from the NCEP global spectral model analysis. The storm environment domain analysis is produced with a two-dimensional spectral application of finite element representation, using all available data (rawindsondes, cloud drift winds, aircraft observations, etc.), with the NCEP global model analysis used as a low level background field. The vortex domain analysis consists of synthetic observations representing storm circulation and current storm motion. The vortex is prescribed to be the same size and intensity in all directions (axisymmetric), with winds increasing linearly from the center to the radius of maximum winds. Wind speeds beyond the radius of maximum winds are prescribed to decrease exponetially to the edge of the storm. In the event of multiple tropical cyclones, synthetic vorticies are included for each storm.Rankine_Vortex

The simplicity of barotropic models means they can be run quickly on inexpensive computers. In the LBAR prediction model, the shallow water equations are solved on a series of nested grid meshes on a Mercator projection. The inner meshes move to remain centered on the storm, while the outer mesh is fixed geographically. Time-dependent boundary conditions from the NCEP Global Forecast System model run are applied outward from a transition zone between 1500 and 2500 km. LBAR runs on a 6-hr forecast cycle and produces forecasts out to 120 hr.

Strengths: LBAR runs quickly (the hurricane specialists can view the output of the 1200 UTC LBAR run before they have to complete their 1500 UTC package). LBAR performs best early in the hurricane season (before fronts penetrate into the subtropics) and on storms that move primarily westward and only move slowly northward. LBAR outperforms all the statistical track guidance models, and its skill in the 12-36 hr time frame is comparable to that of the more complex baroclinic models.

Weaknesses: LBAR does not perform well whenever there is significant vertical wind shear, or when there are multiple, interacting storms.

http://www.srh.noaa.gov/ssd/nwpmodel/ht ... l.htm#LBAR

[wxman57]

A98E is on crack

A98E isn't a very sophisticated "model", it basically uses statistics of past storms that formed in the same area combined with very limited output from the GFS. The "98" part means that it was developed in 1998. You should never follow this model.

LBAR is no better, usually. It very rarely ever has a clue, and when it appears to match some of the better models, it's by accident.

Here is a plot of the dynamic models (BAM, LBAR, Climo models removed). There has been very little change over the past few days. The only possible land mass that Helene might remotely threaten is Bermuda, and it will likely pass far enough east of Bermuda so that all the island would see is high clouds associated with outflow.

[CalmBeforeStorm]

Good question- any pro mets have an answer or what the model might be seeing?

I'm not a Pro Met but I did sleep at a Holiday Inn Express last night. The GFS, GFDL and UKMET all develope a mid level cut-off low off the mid atlantic states that creates the flow that would recurve Helene. The NOGAPS doesn't develope this low and allows a small ridge to devolpe over her.

[pgoss11]

Thank you all for your explanations-

[skufful]

A98E is on crack

A98E isn't a very sophisticated "model", it basically uses statistics of past storms that formed in the same area combined with very limited output from the GFS. The "98" part means that it was developed in 1998. You should never follow this model.

LBAR is no better, usually. It very rarely ever has a clue, and when it appears to match some of the better models, it's by accident.

Here is a plot of the dynamic models (BAM, LBAR, Climo models removed). There has been very little change over the past few days. The only possible land mass that Helene might remotely threaten is Bermuda, and it will likely pass far enough east of Bermuda so that all the island would see is high clouds associated with outflow.

You obviously don't like the "nogaps" models, especially the one that tracks to west. Im ignorant here, so, what are "Nogaps," and why don't you like them?

[CalmBeforeStorm]

Good question- any pro mets have an answer or what the model might be seeing?

I'm not a Pro Met but I did sleep at a Holiday Inn Express last night. The GFS, GFDL and UKMET all develope a mid level cut-off low off the mid atlantic states that creates the flow that would recurve Helene. The NOGAPS doesn't develope this low and allows a small ridge to devolpe over her.

You can see the cutoff low now over NC in this WV loop. Most models continue to develop it and move it off the coast.

http://www.ssd.noaa.gov/goes/east/nwatl/loop-wv.html

[skufful]

Good question- any pro mets have an answer or what the model might be seeing?

I'm not a Pro Met but I did sleep at a Holiday Inn Express last night. The GFS, GFDL and UKMET all develope a mid level cut-off low off the mid atlantic states that creates the flow that would recurve Helene. The NOGAPS doesn't develope this low and allows a small ridge to devolpe over her.

Well Holiday Inn man, help me here. When you look at the animation, at the end, the high is to the right. Why does Helen not track North?