ATL: IRMA - Models

[Frank P]

Stays just off the coast..

[Hurricane Andrew]

Onshore: ECM, UKMET, HMON, CMC, NHC
Offshore: GFS, HWRF, NAM

[MrJames]

18z GFS Ensembles

[Hurricane Andrew]

GFSENS way east...what on earth is going on?

[tolakram]

GEFS

[tolakram]

GFSENS way east...what on earth is going on?

Have you ever looked at the GEFS trend?

[Frank P]

It just amazes me how the center of Irma just kinda snakes around the contour of the SE FL coastline and never makes landfall per the latest HWRF model run... just incredible

[Steve]

18Z HWRF just misses the SE Tip of FL this run similar to the GFS. It's still got 30 hours to go to see where it landfalls on the SE Coast.

HWRF run:
https://www.tropicaltidbits.com/analysi ... 0&ypos=200

Note 84 hours on the HWRF which is at 2:00am EDT Sunday morning. That appears to be the strongest it gets.
https://www.tropicaltidbits.com/analysi ... s=0&ypos=0

HMON which is semi-suspect in my mind (the model itself, not the run), hits South Miami at 84 hours (again, Sunday 2am), comes back out by 96 hours after sliding between Lake Okeechobee and the East Coast and then landfalls again in Southern Georgia. Route is as follows:

Miami > Hialeah > Sunrise > Hollywood > Pembroke Pines/Ft. Lauderdale > Pompano Beach > Boca Raton > Boynton Beach > Lake Worth > Port St. Lucie > Fort Pierce > Vero Beach and back out around Cocoa Beach.

^^ Hopefully that's not the track, because that's a very populated corridor.

[Digital-TC-Chaser]

Think this will do me with the models. Can't see any point from here'in following
any model other than the NHC official track.

[tolakram]

Reminder to those newer to the models thread.

This is not the discussion thread and we try and keep strictly on topic.

Random comments without data will be removed. Questions about model runs are fine, or how to interpret models, I don't want people to hesitate to ask questions. Posts that are removed are generally:

trending
hope this continues
I think blank is blank
I don't think blank

Nothing personal but what someone thinks is not what this thread is about.

Unfortunately sometimes people post in here by accident instead of the discussion thread. During busy times we may delete rather than move these.

Thankyou.

[otowntiger]

The models will fluctuate 20-30 miles one way or another each run I would imagine..overall not much of a change with the 18z GFS. If you correct for its right bias then you would have a Florida landfall most likely.

If the Euro was to trend east overnight then I would consider it more.

It probably will, just not as much as yesterday, and the next run will move back west, just not as much as the day before. I could go on ...

. I agree- when the models get tight and clustered like this they are pretty well locked. This also means that the NHC track is essentially set as well. If there are any 'nudges' they will be small but for Miami sake let's hope they are east. Our local Met here seemed to intimate that any shifts would be east. Let's hope!

[stormreader]

Think this will do me with the models. Can't see any point from here'in following
any model other than the NHC official track.

Almost enough to drive you crazy (watching them so closely). Still very considerable ensemble spread at the latitude of S Fl. Perhaps wake up tomorrow morning and check Euro.

[syfr]

Is there a pointer explaining how models become NHC predictions? I've watched enough models here over the years to recognize that they're volatile and biased, but a pointer to a layman's explanation as to how order is made out of the chaos of models would be really useful for me and probably others.

[PandaCitrus]

In looking at the ensembles, the ones that hit west coast of FL/go into the gulf seem to want to hit Cuba. Are we going to eliminate those possibilities soon? It appears that Irma is making an ever so slight more northerly move now. Am I right that slight north deviations now can have dramatic impacts to if its Miami or goes to the east?

When are we going to KNOW or are we going to be wobble watching till Sunday morning?

[HDGator]

18Z HWRF just misses the SE Tip of FL this run similar to the GFS. It's still got 30 hours to go to see where it landfalls on the SE Coast.

HWRF run:
https://www.tropicaltidbits.com/analysi ... 0&ypos=200

Note 84 hours on the HWRF which is at 2:00am EDT Sunday morning. That appears to be the strongest it gets.
https://www.tropicaltidbits.com/analysi ... s=0&ypos=0

HMON which is semi-suspect in my mind (the model itself, not the run), hits South Miami at 84 hours (again, Sunday 2am), comes back out by 96 hours after sliding between Lake Okeechobee and the East Coast and then landfalls again in Southern Georgia. Route is as follows:

Miami > Hialeah > Sunrise > Hollywood > Pembroke Pines/Ft. Lauderdale > Pompano Beach > Boca Raton > Boynton Beach > Lake Worth > Port St. Lucie > Fort Pierce > Vero Beach and back out around Cocoa Beach.

^^ Hopefully that's not the track, because that's a very populated corridor.

That 18Z run may technically be a miss for landfall but that model really shows a damaging wind field on Irma. Even though the center of the eye is ~40 miles of the east coast of Florida, it's still being raked by 160+ kt winds. At the same time, the Bahamas are seeing slightly higher winds on the eastern edge. This model highlights that a small miss east of Florida coast is still going to have catastrophic wind damage on a highly developed coastline.

[stormreader]

Models keep insisting and taunting East coast Florida residents and visitors on keeping this JUST offshore.

The "big tease". Euro still onshore as of latest run (S Fl). Next 2 Euro runs might go a long way toward telling story. 1am and 1pm Thursday.

[Ken711]

Onshore: ECM, UKMET, HMON, CMC, NHC
Offshore: GFS, HWRF, NAM

Where can I find the latest UKMET?

[tolakram]

Is there a pointer explaining how models become NHC predictions? I've watched enough models here over the years to recognize that they're volatile and biased, but a pointer to a layman's explanation as to how order is made out of the chaos of models would be really useful for me and probably others.

I'm not sure there is a simple explanation. Here's the NHC page: http://www.nhc.noaa.gov/modelsummary.shtml

My amateur interpretation is that the models and their strengths and weaknesses are know, or learned, and all of these go into making the forecast track. Maybe science plus some art? Bottom line is, as they say.

NHC provides detailed information on the verification of its past forecasts with a yearly verification report (http://www.nhc.noaa.gov/verification/verify3.shtml). On average, NHC official forecasts usually have smaller errors than any of the individual models. An NHC forecast reflects consideration of all available model guidance as well as forecaster experience. Therefore, users should consult the official forecast products issued by NHC and local National Weather Service Forecast Offices rather than simply look at output from the forecast models themselves. Users should also be aware that uncertainty exists in every forecast, and proper interpretation of the NHC forecast must incorporate this uncertainty. NHC forecasters typically discuss forecast uncertainty in the Tropical Cyclone Discussion (TCD) product. NHC also prepares probabilistic forecasts that incorporate forecast uncertainty information ( http://www.nhc.noaa.gov/aboutnhcprobs.shtml ).

[stormreader]

Models keep insisting and taunting East coast Florida residents and visitors on keeping this JUST offshore.

The "big tease". Euro still onshore as of latest run (S Fl). Next 2 Euro runs might go a long way toward telling story. 1am and 1pm Thursday.

In other words, if each of the next two Euro runs show landfall in S Fl, I think that will add tremendous credence toward that scenario. Just in case some in SE Fl need one more final confirmation as to the seriousness of the situation.

[RL3AO]

Is there a pointer explaining how models become NHC predictions? I've watched enough models here over the years to recognize that they're volatile and biased, but a pointer to a layman's explanation as to how order is made out of the chaos of models would be really useful for me and probably others.

I'm not sure there is a simple explanation. Here's the NHC page: http://www.nhc.noaa.gov/modelsummary.shtml

My amateur interpretation is that the models and their strengths and weaknesses are know, or learned, and all of these go into making the forecast track. Maybe science plus some art? Bottom line is, as they say.

NHC provides detailed information on the verification of its past forecasts with a yearly verification report (http://www.nhc.noaa.gov/verification/verify3.shtml). On average, NHC official forecasts usually have smaller errors than any of the individual models. An NHC forecast reflects consideration of all available model guidance as well as forecaster experience. Therefore, users should consult the official forecast products issued by NHC and local National Weather Service Forecast Offices rather than simply look at output from the forecast models themselves. Users should also be aware that uncertainty exists in every forecast, and proper interpretation of the NHC forecast must incorporate this uncertainty. NHC forecasters typically discuss forecast uncertainty in the Tropical Cyclone Discussion (TCD) product. NHC also prepares probabilistic forecasts that incorporate forecast uncertainty information ( http://www.nhc.noaa.gov/aboutnhcprobs.shtml ).

The biased corrected ensembles (somewhat like Ventrice posts on Twitter) are probably the biggest tool they use that most of us don't have access to.