ATL: IRMA - Models

[CrazyC83]

Question for the group. Since "the turn" isn't forecast for 6 days, is there anything we should be watching in the models for the next couple of days, to determine if the turn might happen later than currently forecast? I'm asking this as a Northern Gulf Coaster. Thanks for any responses.

I would think that a late turn would require a really, really strong ridge OR a shallower system due to landfall on Hispaniola and Puerto Rico.

[Aric Dunn]

just take a look at the vorticity potential you see that low that just develops.. thats what pushed it north and does not allow the ridging to build back in behind the trough which is what would normally happen..

very odd.. Steve take a look.. its not a second push f the trough.. the trough is gone and this mid to upper low form and drives it north . .

https://www.tropicaltidbits.com/analysi ... 6870117188

[ronjon]

Heading for Pittsburgh again on GFS.

[RL3AO]

Question for the group. Since "the turn" isn't forecast for 6 days, is there anything we should be watching in the models for the next couple of days, to determine if the turn might happen later than currently forecast? I'm asking this as a Northern Gulf Coaster. Thanks for any responses.

If this trough keeps trending stronger and further east in the 5 to 6-day timeframe, that would support a sudden turn a little further east.

[otowntiger]

18z GFS 192 -> 222

Ok- I'm guessing that was some kind of a glitch, lol? A 978 storm would not just disappear like that right at the end . That was almost comical.

[SFLcane]

So basically nerve recking w trend for SFL continues..long ways to go but we certainly are not heading in the right direction.

[northjaxpro]

I pray that trough can catch Irma at the end of the run. We have seen these troughs spare Florida numerous times, like Floyd in 1999.

But you wonder when our luck is going to run out with these cyclones ... This is what makes me feel rather unsettled about this upcoming week.

[AutoPenalti]

just take a look at the vorticity potential you see that low that just develops.. thats what pushed it north and does not allow the ridging to build back in behind the trough which is what would normally happen..

very odd.. Steve take a look.. its not a second push f the trough.. the trough is gone and this mid to upper low form and drives it north . .

https://www.tropicaltidbits.com/analysi ... 6870117188

Maybe it's the government helping us out.


In all seriousness, I'm not really buying this run for the same reason you explained. That low just appears out of nowhere and it just doesn't seem right.

[weathaguyry]

It appears that interaction with the feature over the MS valley slows this thing down and shoots it NW, so this feature will probably be one of the most important

[Aric Dunn]

just take a look at the vorticity potential you see that low that just develops.. thats what pushed it north and does not allow the ridging to build back in behind the trough which is what would normally happen..

very odd.. Steve take a look.. its not a second push f the trough.. the trough is gone and this mid to upper low form and drives it north . .

https://www.tropicaltidbits.com/analysi ... 6870117188

or better yet here
.. its plain as day that the trough is way way gone..

then the low forms and up goes IRMA
https://www.tropicaltidbits.com/analysi ... 3129882812

[stormreader]

Landfall on the 18z gfs is North Carolina at 887mb. There's never been one anywhere close to that to hit North Carolina and I doubt the TCHP would even support such.

I don't buy the stall in at 174-180 time period either...This thing is most likely going to have about the same set-up as Frances.

That "stall" caught my attention. Would mean the model is sensing overall weaker steering at that point. The model then returned to earlier runs forecasting north after that. But that "stall" could be a signal that future runs might not offer the same due north solution in later hours. In other words, don't be surprised if later runs offer a significantly more west component from the point of the "stall" on this run. Will look for that.

[northjaxpro]

I pray that trough can catch Irma at the end of the run. We have seen these troughs spare Florida numerous times, like Floyd in 1999.

But you wonder when our luck is going to run out with these cyclones ... This is what makes me feel rather unsettled about this upcoming week.

[AxaltaRacing24]

I pray that trough can catch Irma at the end of the run. We have seen these troughs spare Florida numerous times, like Floyd in 1999.

But you wonder when our luck is going to run out with these cyclones ... This is what makes me feel rather unsettled about this upcoming week.

The trend is not our friend

[Kingarabian]

18z GFS 192 -> 222

[img]https://i.imgur.com/FlGHKKo.gif[img]

Ok- I'm guessing that was some kind of a glitch, lol? A 978 storm would not just disappear like that right at the end . That was almost comical.

Hi res it does that overland. Here this one is better:

[Aric Dunn]

if that upper low does not form IRMA would have just kept heading w to wnw into the gulf..

[Steve]

just take a look at the vorticity potential you see that low that just develops.. thats what pushed it north and does not allow the ridging to build back in behind the trough which is what would normally happen..

very odd.. Steve take a look.. its not a second push f the trough.. the trough is gone and this mid to upper low form and drives it north . .

https://www.tropicaltidbits.com/analysi ... 6870117188

Yeah, I see that. Looks like a piece splitting down from somewhere or something. I don't know because you can't see a source for how it even develops it. If you run the same map at the North Atlantic level, you can see what I was saying about North of Irma and how it's wrapping around the top between the trough and north of the system. I think it will move NW inland based on that at least toward Ohio or maybe Indiana.

Here's the map with the full North Atlantic view.
https://www.tropicaltidbits.com/analysi ... 318&fh=-18

[Happy Pelican]

As for pressure, one of the big guns on twitter(Ryan?) said that since the GFS was updated, in terms of a storms strength add +50 and that is what the actual mb's will be.

As for the models, this is my gut and my opinion so hear me out, I really think Irma's going to split the difference and head straight up into either the Delmarva or split NJ in half. Again, just my gut. I have that same, uneasy feeling I had with Sandy and yes, I know it's two different systems but something in these models is leading down that train of thought.

Also, if Irma turns in for landfall just a bit north of where the 18Z GFS has her, it still puts NJ in the NE quadrants and we'll see a surge from her and given how bad everything floods since Sandy, it's going set countless homeowners 10 steps back who still aren't finished rebuilding after nearly 5 years.

Again, just my OPINION. Don't take it as a forecast or even remotely serious.

[Vdogg]

GFS slightly east of 12z. Trend toward ECMWF?

I would not say it's a trend towards ECMWF because ECMWF hasn't even trended to itself. It's vacillated wildly between landfall and OTS the past several runs even though it's ensembles have generally favored landfall. Once the Euro starts dialing in on a solution then we can see if other models trend to it or not.

[weathaguyry]

if that upper low does not form IRMA would have just kept heading w to wnw into the gulf..

I'm not sure, without that low, steering currents are fairly weak around hour 150, no giant ridge that would push anything into the gulf, maybe it would meander off of florida if the low wasn't there? Just a total guess.

[hohnywx]

 https://twitter.com/RyanMaue/status/904470166590894080