ATL: IRMA - Models

[Emmett_Brown]

IRMA is south of even the 6 hour GFS track already. That should tell you something not to mention the model has been right-biased for most of this storm. Remember when it showed it going north of the Leewards several days ago?

Yep, the 0z Euro was much closer to predicting the current position.

[Mouton]

I don't care what models they are posting...there is a trend, there is a cone. As of the last many models have shown, they are still inside the cone, just more on the rightish side now. That may and will probably change again. For me, I am having a lot of trouble seeing what is causing a 90 degree sharp turn in the projected path. I do notice the angle of attack from St Maartin seems to be showing an increasing NW direction. If this were to continue, it would miss the entire east coast, a path I do not fathom happening. The current long term path of the GFS and Euro I believe shows two left bends, one abreast of Hispaneola and one above the Fl/Ga line. That seems to indicate to me higher pressures to the NE, building, receding, rebuilding hence the movement in the models from left to right and back again IMO. 4 days out now and the throat of the cone is narrowing for S Florida.

[bsidella]

What drives the average person crazy are the shifts and being told not to concentrate on the center. Ok then why put in a center line at all? Obviously that line draws in your focus and you can tell a person a thousand times "wet paint" and most will put a finger on it. The model shifts for this storm have been crazy. With all the billions spent on hurricane modeling we cannot see 5 days into the future how in the hell can anyone look ahead 10-50 years with Global Warming models.

[tolakram]

We can't control what the media show or what people believe. Every time this happens (every year land is threatened) the story is the same. I did not hear what the announcer said, I only see a single picture frame. Let's drop this discussion, it's not constructive. Let's also drop the trend east vs west silliness. We went through this with Matthew and it trended back west the next day before finally ending up just barely off the coast of Florida.

[HurricaneEric]

Really starting to get annoyed by all these spaghetti plots of deterministic models, half of which are trash. I know many on this board understand what they mean and that they can change, but from social media, I get the feeling a good chunk of the public is being deceived.

Use the ensembles to your advantage. Even in the notoriously under-dispersive GEFS, there are still multiple members that hit FL, including the west side of FL. The EC ensembles are actually centered on FL. The ensembles are designed to represent the amount of uncertainty in a given forecast. With the large spread in the members, it is clear there is a lot we are still unsure about in the track forecast of Hurricane Irma. Anyone within this spread should not let their guard down. There is a reason the NHC's cone is as wide as it is. This is a tricky forecast. Prepare for the worst and hope for the best.

Sorry for the rant.

Agreed. There already seems to be a premature sigh of relief here in Miami. This is so irresponsible and unfortunately these news stations showing the spaghetti models just exacerbates the issue. Already know some people down here saying it'll recurve before FL and Miami is safe, even here on this board...

Please DO NOT make assumptions based off one run of models. As stated by SouthDadeFish and tolakram, plenty of the ensembles have this over Florida as well as the cone. This premature sigh of relief is approaching very dangerous territory. Lets be a little more informed and reasoned when we talk or post about this and understand that anywhere within the cone of uncertainty is in play.

[ColdFront77]

People are not educated enough about this stuff, they think lines are shifting east means that it's out to sea or that it won't be threatening SFL. I have friends who shared that same exact plot and are all angry at me and telling me that "I'm scarying people for no reason, I knew this was going out to sea to begin with, it's not coming, I bought all this stuff for no reason", little do they know that they can change right back to the spine.

The issue is if the meteorologist bluntly said that they will not shift and that the models are forecast guidance, not an actual forecast. It truly ridiculous if he did not show the National Hurricane Center's official forecast track and the more reliable hurricane forecast models.

Showing the ensemble model runs are just as important to show in circumstances like this as well.

[nativefloridian]

So Local 10 showed fellow viewers this spaghetto plot.


upload an image

Not sure why but they really hammered it hard.

That's very irresponsible of them IMO...I can't believe they are showing that on TV

Why is that irresponsible? Models are models, they need to understand all of the information and be informed to make a decision, this is massive people movement we are talking about. If the models continue to trend east and up the coast to the carolinas as projected then that is great news for FL.

Great news for FL? I agree with the comments made about the media (tv & social) underplaying the seriousness of this storm and how large this storm is if it veers just offshore! Is that being irresponsible? IMO, I say yes! This storm is much larger than the width of the State of Florida and there are too many living in Florida now that have no idea what it's like to go through a catastrophic hurricane. Being born and raised in South Florida, since 1957, I've been through my share of TS/Hurricanes and I will be first to say that the most important thing is to not let your guard down regardless of what this or that model says. Please pay attention to the NHC's forecast as, I feel, they are the most reliable source of information! OK, I'm done with my rant....and thanks for listening. I'll be moving this comment to discussion thread.

[USTropics]

Why are folks saying that South Florida is looking better? Actually it looked better yesterday with the core passing around Key West. Now the consensus of the GFS and ECMWF has the core just offshore the SE Coast of Florida coming in from the SOUTH raking the entire SE Florida coastline. If that track holds, Matthew's impacts on SE Florida will pale in comparison! Matthew came in from the SE and was far enough away SE Florida to not cause a big issue.

Here is what the best performing model is doing. Things are looking better? I don't think so:

its about the trend, if the trend continues its good but the danger is now we coudl take a direct hit where yesterday it looked as though it had a chance to go into the gulf and that seems to be decreasing...our risk for a direct hit has actually increased today but so has east of us...high stakes for sure

Good point. Also, on that Euro run, there are 24 hour increments between positions.... so it is possible that a direct SFL landfall occurs but is not visible due to the time increment.

Also want to reiterate that models should not be the only tool when making a reliable forecast. The NHC has a plethora of other tools at their disposal, including decades of experience doing this for a living. Always follow the NHC cone and advisories.

Models have errors (the ECMWF, our best performing model, has a positional error of 120 nautical miles for Irma at 96 hours). Model bias has also been to the right at hour 96:

[Jevo]

The GFS has already missed it's first 6z plot to the South... I'm feeling that the Euro may have corrected itself and the GFS still may be the Easterly outlier.

[shawn6304]

its about the trend, if the trend continues its good but the danger is now we coudl take a direct hit where yesterday it looked as though it had a chance to go into the gulf and that seems to be decreasing...our risk for a direct hit has actually increased today but so has east of us...high stakes for sure

Good point. Also, on that Euro run, there are 24 hour increments between positions.... so it is possible that a direct SFL landfall occurs but is not visible due to the time increment.

The ECMWF solution was uncomfortably close to landfall:



You can get high-resolution images for ECMWF now at http://weather.us.

this is actually worse then a landfall in some ways as in the fact that it will not decrease while still over water.

[Jevo]

[sma10]

Why are folks saying that South Florida is looking better? Actually it looked better yesterday with the core passing around Key West. Now the consensus of the GFS and ECMWF has the core just offshore the SE Coast of Florida coming in from the SOUTH raking the entire SE Florida coastline. If that track holds, Matthew's impacts on SE Florida will pale in comparison! Matthew came in from the SE and was far enough away SE Florida to not cause a big issue.

Here is what the best performing model is doing. Things are looking better? I don't think so:

And this doesn't even show the intermediate points between the 24hr jumps. The hi-res shows the western eyewall raking Miami, FLL and PBI at ~925mb

[Blown Away]

And then Ryan Maue tweets this... :
 https://twitter.com/RyanMaue/status/905419696740151296

Some amateur analysis, Irma appears to be just S or on the mean consensus... Most of the N consensus tracks curve E of Florida...

[Recurve]

We can't control what the media show or what people believe. Every time this happens (every year land is threatened) the story is the same. I did not hear what the announcer said, I only see a single picture frame. Let's drop this discussion, it's not constructive. Let's also drop the trend east vs west silliness. We went through this with Matthew and it trended back west the next day before finally ending up just barely off the coast of Florida.

Thank you!
This "only we are smart enough to look at models" discussion is pointless. ABC Ch. 10 in Miami has had Max Mayfield on staff since he left the NHC. Don't worry about Miami stations underplaying the threat. They are doing hours of coverage. Slamming them for one frame is off-topic. Let's save the media-metanalysis for post-storm.

[Category6]

Really starting to get annoyed by all these spaghetti plots of deterministic models, half of which are trash. I know many on this board understand what they mean and that they can change, but from social media, I get the feeling a good chunk of the public is being deceived.

Use the ensembles to your advantage. Even in the notoriously under-dispersive GEFS, there are still multiple members that hit FL, including the west side of FL. The EC ensembles are actually centered on FL. The ensembles are designed to represent the amount of uncertainty in a given forecast. With the large spread in the members, it is clear there is a lot we are still unsure about in the track forecast of Hurricane Irma. Anyone within this spread should not let their guard down. There is a reason the NHC's cone is as wide as it is. This is a tricky forecast. Prepare for the worst and hope for the best.

Sorry for the rant.

Amateur here, don't know much about models. Can you explain the difference between the singular model tracks posted on here and the ones you see on the news vs. the ensembles? Thanks!

My attempt at explaining:

Basically, different organizations run a main model (deterministic), if you will, at a relatively high spatial resolution, using the best observations we have. Then we also run ensembles, which are slightly lower resolution versions of the same model (for the most part) that try to account for things we are unsure of. For example, one ensemble member may have a stronger ridge to the N of Irma than the deterministic model to account for potential error in observations or a lack of observations. Another ensemble member may have a stronger trough than the deterministic model. As a result, the outcome of the ensemble simulations will be different. By running many different ensemble simulations, we hope to capture the total range of realistic possible outcomes. We can then use this information to get an idea for what the probability of a certain outcome is. If many ensemble members are predicting a similar outcome, then that forecast is believed to be more likely.

That explanation was crudely summarized and those mets more familiar with modeling can feel free to correct anything I said.

More info here: https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/global-ensemble-forecast-system-gefs

Thanks! this was very insightful.

[stormreader]

I'm having a tough time buying into the E of Fl track. Anything is possible, but knowing that all models show no escape route to the east further north, the longer term trend to the west, and the reluctance ( I think rightfully so) for the NHC to move the track further east, I still think most, if not all, S Fl will be in the right-front quadrant. I also think that the earlier S dip the Euro had over Cuba will be "smoothed over" (think that already happened on its last run). So storm should keep to WNW over water just about all the way to the tip of Fl. I'll stay with a landfall at Naples. but I think in any case, with overall trends, and what I said earlier, a trek off the Fl coast to the east is less likely.

[stormreader]

I'm having a tough time buying into the E of Fl track. Anything is possible, but knowing that all models show no escape route to the east further north, the longer term trend to the west, and the reluctance ( I think rightfully so) for the NHC to move the track further east, I still think most, if not all, S Fl will be in the right-front quadrant. I also think that the earlier S dip the Euro had over Cuba will be "smoothed over" (think that already happened on its last run). So storm should keep to WNW over water just about all the way to the tip of Fl. I'll stay with a landfall at Naples. but I think in any case, with overall trends, and what I said earlier, a trek off the Fl coast to the east is less likely.

[p1nheadlarry]

Can someone give me an understanding about why there seems to be a discrepancy between the West/East tracks? My feeling all along is that it would glide up the coast, but I abandoned that idea for FL/FL gulf side idea.

From what I can tell, it's how the models are handling the shortwave that is in the northwest. Timing and strength, which seem to be harder for shortwaves than normal troughs, will determine when the ridging to the north of Irma starts to weaken and allow an escape to the north. Easterly-tracking models have a stronger shortwave.

[Vdogg]

NHC will probably put the 5 day point just off the Palm Beach County coast. Models can still shift back West, but it's looking slightly better for South Florida this morning.

You called it. It shifted ever so slightly east.

[stormreader]

Seems slow at this site. Checking to see if posts are going through.