ATL: IRMA - Models

[SFLcane]

06z GFS ensembles are up the spine of Florida..

[tolakram]

[chaser1]

That model bias map is fascination...EVERY single model has been too far east...hmm...

Model bias map? Could you repost?

[ronjon]

Interesting that the most southern individual ensemble runs of the 06z GFS are the furthest west into Florida - this will be something to watch the next few days based on the actual track of Irma and might hint at the eventual landfall point in Florida.

[USTropics]

That model bias map is fascination...EVERY single model has been too far east...hmm...

Model bias map? Could you repost?

Positional error by forecast hour:


Model positional bias:


You can find these type of charts here - http://www.atmos.albany.edu/facstaff/tang/tcguidance/

[Steve H.]

Interesting that the most southern individual ensemble runs of the 06z GFS are the furthest west into Florida - this will be something to watch the next few days based on the actual track of Irma and might hint at the eventual landfall point in Florida.

Good point and it makes perfect sense. Watch the southern points on Friday/early Saturday.

[adam0983]

What is the timing according to the latest models for palm beach,broward and dade county.

[RL3AO]

Model positional bias:
[img]https://i.imgur.com/ycZf6mR.png

You can find these type of charts here -

And the biased corrected models and ensembles that the NHC has is probably the main reason they've been to the left of many models. NHC looks at a lot more stuff than a TV met has time to look at. Really should listen to the NHC at this point.

[Spoomsister]

Does anyone know of a link with animated radar overlayed with forecast points? I can not seem to find one.

[p1nheadlarry]

Model positional bias:
[img]https://i.imgur.com/ycZf6mR.png

You can find these type of charts here -

And the biased corrected models and ensembles that the NHC has is probably the main reason they've been to the left of many models. NHC looks at a lot more stuff than a TV met has time to look at. Really should listen to the NHC at this point.

I said it yesterday in jest, but local/national news should have the NHC website URL at the bottom of the screen like the coverage is an 80's telethon.

[AutoPenalti]

Did the GEFS ensembles shift west again? Sorry guys I just woke up, we are doing final preps for evacuation.

We leave tonight.

[Cuda]

That model bias map is fascination...EVERY single model has been too far east...hmm...

Model bias map? Could you repost?

Positional error by forecast hour:


Model positional bias:


You can find these type of charts here - http://www.atmos.albany.edu/facstaff/tang/tcguidance/

Just a thought, but wouldn't the east bias have more to do with underestimating forward speed than steering? Right now the storm is moving, mostly E-W. That positional bias is mostly influenced by speed of the storm. Whereas, where it really matters it'll be moving N/S and the east bias at that point would be more of a steering error than a speed error....

Or am I thinking of this wrong?

[Steve]

06Z HMON begins "landfalling" (Bay Falling) with landfall against the park islands in Biscayne Bay at 72 hours. Pressure is probably way overdone at 876mb. The eyewall takes a track along the coast to West Palm Beach/Jupiter where it goes offshore. It finally landfalls again just on the north side of the Savannah River (SC Side of the border) around 99 hours at 939mb pressure. This would be probably Cat 3 but weakening at that point. I think it's relatively stronger at 2nd Landfall than some of the runs that landfall more into Florida because it has less land interaction. Alternatively, it's much weaker than the models that keep Irma offshore of Florida and consequently bring it into the GA/SC Coast around 900mb. The way I'm leaning is that I think HMON is overdone on pressure both at first landfall/landtouch (876mb) and overdone at second landfall, which based on what I think will happen, is more likely to be 950's, 960's or even 970's.
https://www.tropicaltidbits.com/analysi ... 0&ypos=734

06Z NAVGEM is much farther up the west coast of Florida. NAVGEM comes up through the FL Keys, is just offshore of Cape Coral at 84 hours, and landfalls around hour 90 near Sarasota/Longboat Key/Bradenton/St. Pete Beach. It's up in NE FL by 108 hours, moves into Southern Georgia and never comes back offshore. I think the NAVGEM shows Irma to be weaker than it is which may have calibrated the track too far west.
https://www.tropicaltidbits.com/analysi ... 0706&fh=90

[SEASON_CANCELED]

Did the GEFS ensembles shift west again? Sorry guys I just woke up, we are doing final preps for evacuation.

We leave tonight.

storm is still days away. That cone could slide to bermuda or Brownsville. Ive seen it happen...the cone is self correcting..so it looks like its never wrong. Its really only 99% accurate 24 hours out...and even then you get situations like Charlie where it turns direction at the last minute

[AutoPenalti]

FWIW, Eric Webb is mentioning about how GFS is showing the east outlier because of a slow down in the trough.

[tolakram]

Did the GEFS ensembles shift west again? Sorry guys I just woke up, we are doing final preps for evacuation.

We leave tonight.

storm is still days away. That cone could slide to bermuda or Brownsville. Ive seen it happen...the cone is self correcting..so it looks like its never wrong. Its really only 99% accurate 24 hours out...and even then you get situations like Charlie where it turns direction at the last minute

No, it's timing dependent. http://www.nhc.noaa.gov/aboutcone.shtml

[caneman]

FWIW, Eric Webb is mentioning about how GFS is showing the east outlier because of a slow down in the trough.

What does this,mean? Storm goes more west or east?

[Ken711]

FWIW, Eric Webb is mentioning about how GFS is showing the east outlier because of a slow down in the trough.

Does that mean it will continue to trend east in successive runs?

[AutoPenalti]

FWIW, Eric Webb is mentioning about how GFS is showing the east outlier because of a slow down in the trough.

Does that mean it will continue to trend east in successive runs?

It means that it might go east than forecasted.
It's based off of the last runs.

We'll see if it changes at 12z.

This is what he has to say about the Euro

 https://twitter.com/webberweather/status/905653419247001603




 https://twitter.com/webberweather/status/905655953541873664




I think he's known to favor the GFS more, can anyone else chime in on this?

[tolakram]

It means that it might go east than forecasted.
It's based off of the last runs.

What's his experience and verification record compared to the NHC. He might be awesome but I'm skeptical of skeptics this late in the game. The GFS error rate is large and has been right of actual track almost constantly, if not constantly.