ATL: IRMA - Models

[Ken711]

Canadian 12Z

Close to the GFS Position at 96 hours (Sunday morning) and ends up hitting NC later.

HWRF looking big and bad at 920mb moving toward Miami at 87 hours. At 96 hours it's about 1/2 degree East and 1/4 degree South of Miami hedging closer. This will be the most watched hurricane in history if the new runs end up verifying. Remember, we're now within 5 days where the track accuracy markedly improves.

How accurate has CMC been with Irma's track?

[SouthFLTropics]

Brutal runs from the HMON and the HWRF...HWRF with the eyewall scraping the coast moving North. I'll post that section of the run once it's complete.

[Evil Jeremy]

I remember like it was yesterday when the GFDL was the darling new model after nailing Katrina's swing through South Florida...that didn't last long.

I remember like it was yesterday when the HWRF was introduced with the intention of replacing the GFDL.... that didn't last long either.

[chris_fit]

That's a decent shift W and I call that Landfall...

[Voltron]

Question:

In earlier runs, the models had Irma puling a Hugo and going up through Raleigh North. Not it is doing this bending where it hits between Savannah and Charleston and going NW into the states and up through Western NC. What is causing that and is there a component that would shift it more North once it hits in SC say?

Look at Canada and the strong High Pressure coming down into Ontario and NY State or thereabouts. Looks to be a pretty strong high (though not all that big) that comes over top and forces it that way. It's a trend we started talking about a week ago or so and in my mind was the one thing that would force a landfall regardless of whether or not it ever hit Florida. Remember that the circulation around a high is clockwise, and the circulation of a low is counter clockwise. It can't realistically (though I'm sure it's happened a time or two) bounce off the south of that airmass and go East. It would have to follow the path of least resistance as fluids usually do (air is essentially a volume of fluids). Hope that helps. If not, run your models at the North American level rather than CONUS or W Atlantic and you can see how it unfolds. The trough lifts out and the high comes down in its place. It's one example of what they call a "block" or "blocking high."

thanks that is very helpful, I missed that so sorry! So this could be off some and it could be more the the North straight depending on the blocking ridge and where located then

[tolakram]

12z euro init

[AutoPenalti]

Noticeable west shift on the HWRF.

[tolakram]

HWRF animation

[Steve]

Canadian 12Z

Close to the GFS Position at 96 hours (Sunday morning) and ends up hitting NC later.

HWRF looking big and bad at 920mb moving toward Miami at 87 hours. At 96 hours it's about 1/2 degree East and 1/4 degree South of Miami hedging closer. This will be the most watched hurricane in history if the new runs end up verifying. Remember, we're now within 5 days where the track accuracy markedly improves.

How accurate has CMC been with Irma's track?

Not very good beyond 12-24 hours. It's not the worst, but it's relatively bad.

Also, at 108 hours, HWRF still has the center offshore but the eyewall along the coast at Boynton Beach/Delray Beach, West Palm Beach. Shows 932 so probably still a Cat 4. HWRF so far has the center offshore but the eyewall right along the beaches. There's some pricey real estate along the A1A corridor.

[WxGuy1]

Topic is temporarily locked.

Euro runs at 1:45PM, HWRF is running now.

Too much back and forth in here, and frankly I don't care where you think it's going unless you are a model (not that kind of model ), or are interpreting a model. There's too much thinking without enough evidence in here and it's not helpful.

It will be unlocked shortly.

Think of all the effort and time that has been spent on Storm2K analyzing each model run out to 120+ hours down to nearly the mile, only for it to be rendered nearly useful in 6 hours when the next run of the model(s) come(s) in.

Frankly, we can guarantee that the current models will not be 100% correct. Who am I to tell anyone how to spend his/her time, but this thread currently has more than 8000 posts (!) and is more than 400 pages long. I mean absolutely no disrespect to any specific posters/participants here, but there are a lot of "We'll have to wait and see what X model says [at some future run]" and really overanalyzing the models. Of course "the next few runs" will tell us a lot, but that's almost always the case. Tomorrow, we'll see posts like "Wow, the next run will be extremely important" and "The atmosphere will be better sampled tomorrow, so tomorrow's runs will be the most important yet", which are fine but really obvious.

Now, for something more relevant to specific model output for Irma... Any brush with the mountainous terrain of Hispaniola or eastern Cuba should cause some detrimental impact on Irma. Although very, very bad for those areas (!), it would be of some benefit to the U.S. coastal communities. The wiggles and waggles that the models continue to show are normal in my experience, and I'd reiterate that it's really not worth the time right now to analyze each model run from each model down to the mile.

Would land interaction before the turn also increase the possibility of a larger wind field and hence surge?

That's a good question. I'm really not sure how much we know about the factors that modulate the size of tropical cyclones. In my experience, cyclones *tend* to get larger as they "age", but this certainly isn't always the case. We've certainly seen tropical cyclones in the past that grow with time, even if max sustained winds don't increase. The absolute "damage potential" of a larger but perhaps not as intense cyclone may be greater than that of a smaller but very intense cyclone. Wilma caused a lot of damage when it crossed Florida in 2005, even though it was "only" a mid-range Cat 3 that weakened into a Cat 2 during the time is traversed the state. Wilma caused ~$20 BILLION in damage in Florida. Matthew was similar intensity when it was near the coast of Florida (max sustained ~120 mph), but caused "only" $3 billion in damage in Florida (according to Wiki at least).

[tolakram]

[RL3AO]

Euro a little faster still. That's a big part of why the models have shifted east. Reaches the turning point before the ridge builds back in.

[Steve]

Hey Voltron,

This should answer your question fully. Run this NAM 12km resolution 12Z and look up toward the Great Lakes toward the end of the run. At 72 hours the high is centered across Wisconsin. 84 Hours it's on the U.P. of Michigan. It's a progressive high in that it's moving west to east (progressing) across the northern tier. If NAM went out farther, it comes east and blocks a NE alleyway out to sea. I only suggest this for overview, not for track of Irma.
https://www.tropicaltidbits.com/analysi ... 0&ypos=468

It may make more sense to you to look at it in shaded colors as well. Look at the 500mb Height & Anomalies. Red is high pressure. Blue is low pressure. Watch the evolution as the Trough lifts out, and this should explain better than I can what happens. The high is basically NE/N and NW of Irma which is why it has the west hook.
https://www.tropicaltidbits.com/analysi ... 0&ypos=601

[MatthewsRevenge]

Can't tell if Euro has changed much from 00z? Probably has but I can't tell, we'll have to see where it goes in 15 minutes.

[MatthewsRevenge]

Heading to the Bahamas but could still go NW here:

[bonjourno]

Levi's server is certainly getting a workout. Think I'll just wait for the model images to pop up here instead of constantly trying to F5...

[tolakram]

[SouthFLTropics]

GEFS Ensembles for your afternoon viewing displeasure...

[SouthFLTropics]

GEFS Ensemble 06z to 12z Trend...MAJOR DIFFERENCES

[tolakram]