ATL: IRMA - Models

[curtadams]

What's crazy, the GFS/Euro are stronger than HWRF...

As a number of posters have pointed out, the GFS typically grossly overestimates the pressure strength of large typhoon-like storms. I don't know about the Euro's biases but in general the HWRF is already pretty bullish so the Euro probably just unable to estimate the pressure of this storm either. The HMON is obviously off the deep end and there's not really any excuse since it's supposed to be a hurricane model and not a general model. It needs some reprogramming. The only concern I have with the HMON result that the crazy result indicates the storm is too strong for the HMON's programming - which is a bit concerning.

I would expect the storm to be somewhat weaker than the HWRF's prediction, based on the known biases of the models. Of course, model failures notwithstanding, we're looking at a high likelihood of a near-record or record storm rampaging through the Bermudas in a week and that's quite bad enough even if sub-900 pressure is very unlikely.

[northjaxpro]

A storm projected to be massive in size when in the Bahamas next weekend, I would find. it hard for it to make such an abrupt right turn shown above. The storm would have to slow down and make a gradual turn imo.

[eastcoastFL]

Another look at the hard right turn before reaching SE Florida. Have to say, if it ends up doing something like that, talk about a nail biter and yet another lucky escape for a South Florida (and yet another not so lucky hit on the Bahamas). You can't rule it out but seems a bit suspicious especially looking at the ensembles:

I don't not like the looks of that. I'd have to say even if it's supposed to come close but not make landfall I'm going to be heading towards the pan handle.

[RL3AO]

A reminder that Bastardi's forecast is not a model and should not be put in this thread. Feel free to put it into the discussion thread.

[jdjaguar]

What's crazy, the GFS/Euro are stronger than HWRF...

As a number of posters have pointed out, the GFS typically grossly overestimates the pressure strength of large typhoon-like storms. I don't know about the Euro's biases but in general the HWRF is already pretty bullish so the Euro probably just unable to estimate the pressure of this storm either. The HMON is obviously off the deep end and there's not really any excuse since it's supposed to be a hurricane model and not a general model. It needs some reprogramming. The only concern I have with the HMON result that the crazy result indicates the storm is too strong for the HMON's programming - which is a bit concerning.

I would expect the storm to be somewhat weaker than the HWRF's prediction, based on the known biases of the models. Of course, model failures notwithstanding, we're looking at a high likelihood of a near-record or record storm rampaging through the Bermudas in a week and that's quite bad enough even if sub-900 pressure is very unlikely.

First up, lesser Antilles, Bahamas, Florida, then maybe Bermuda

[mitchell]

Anyone have a good idea of what size waves that would create in those fairly shallow seas.

If the seas are really that shallow, then the wave height would be "depth-limited"

For example, max wave height in shallow waters is about 60% of depth. When waves reach that height, they begin shoaling (breaking) and can get no higher. So in 50 feet of water without abrupt changes in bathymetry, no matter the wind speed or duration, waves heights will generally not exceed about 30 feet.

[CrazyC83]

Based on some of the models trending towards the coast or up the spine of the state,what conditions would or could the west coast of Florida Such as Sarasota,St.Petersburg, Tampa exspect?

not much...one of the biggest mistake meteorologists make is overstating impacts on west side of storm. We had nothing of note from Matthew.....it's bad if you are in eyewall...but shore of that, west side of a hurricane is the place to be..

Corpus Christi was at the fringe of the west eyewall of Harvey and only had category 1 conditions at most (a big mistake for those saying "we survived Harvey" if a future storm threatened them).

[CrazyC83]

A storm projected to be massive in size when in the Bahamas next weekend, I would find. it hard for it to make such an abrupt right turn shown above. The storm would have to slow down and make a gradual turn imo.

Most models DO slow down Irma in that area too - that is terrible news for the Bahamas though. Almost like pulling a Joaquin.

[otowntiger]

00z Guidance... TVCN Consensus buying into R turn...

Yeah, but look at the ensembles though, +50% have them right over FL.

LOL. I think the TVCN track is a "shout-out" to the Florida protective shield

lol. Looks like they literally run hard into a brick wall.

[txwatcher91]

Based on some of the models trending towards the coast or up the spine of the state,what conditions would or could the west coast of Florida Such as Sarasota,St.Petersburg, Tampa exspect?

not much...one of the biggest mistake meteorologists make is overstating impacts on west side of storm. We had nothing of note from Matthew.....it's bad if you are in eyewall...but shore of that, west side of a hurricane is the place to be..

Corpus Christi was at the fringe of the west eyewall of Harvey and only had category 1 conditions at most (a big mistake for those saying "we survived Harvey" if a future storm threatened them).

A few key differences with Irma though is that models have the wind field MUCH larger than Harvey’s was. Harvey was fairly compact for hurricane force winds but Irma will be much larger. Also, the enhancement from the high pressure to the north will heighten the pressure gradient. With Irma, a pass of the western eyewall within 50 miles of FL as a cat 5 would likely bring sustained hurricane force winds to coastal areas based on the Euro and GFS output.

[northjaxpro]

A storm projected to be massive in size when in the Bahamas next weekend, I would find. it hard for it to make such an abrupt right turn shown above. The storm would have to slow down and make a gradual turn imo.

Most models DO slow down Irma in that area too - that is terrible news for the Bahamas though. Almost like pulling a Joaquin.

Yeah that's what I thought of course in my years of analysis when they get this size I can't ever recall seeing a massive tropical cyclone making such a abrupt movement change like that image showed above. Yes, any slow down or near stall will be catastrophic in the Bahamas at the intensity that the models are showing it to be at that time so we will watch and just hope for the best scenario, but it's looking very very ominous that Irma is going to get very close to the Florida East Coast by next weekend.

[otowntiger]

Another look at the hard right turn before reaching SE Florida. Have to say, if it ends up doing something like that, talk about a nail biter and yet another lucky escape for a South Florida (and yet another not so lucky hit on the Bahamas). You can't rule it out but seems a bit suspicious especially looking at the ensembles:

. Yep. Very odd. Another view of the brick wall run, lol.

[Michele B]

A storm projected to be massive in size when in the Bahamas next weekend, I would find. it hard for it to make such an abrupt right turn shown above. The storm would have to slow down and make a gradual turn imo.

Most models DO slow down Irma in that area too - that is terrible news for the Bahamas though. Almost like pulling a Joaquin.

Yeah that's what I thought of course in my years of analysis when they get this size I can't ever recall seeing a massive tropical cyclone making such a abrupt movement change like that image showed above. Yes, any slow down or near stall will be catastrophic in the Bahamas at the intensity that the models are showing it to be at that time so we will watch and just hope for the best scenario, but it's looking very very ominous that Irma is going to get very close to the Florida East Coast by next weekend.

My experience has been that if/when a storm stops, or slows waaay down, it's getting ready to make a change in direction. So if it were to stop, or slow considerably over the Bahamas, I would expect the very sharp northerly turn after that.

[SapphireSea]

Based on some of the models trending towards the coast or up the spine of the state,what conditions would or could the west coast of Florida Such as Sarasota,St.Petersburg, Tampa exspect?

not much...one of the biggest mistake meteorologists make is overstating impacts on west side of storm. We had nothing of note from Matthew.....it's bad if you are in eyewall...but shore of that, west side of a hurricane is the place to be..

I had mentioned this before when Matthew was threatening S. Florida. Mets often "Hype" (state, but a bit overstated) the west side of the storm, and often times aside from gusts and rain it is not particularly life threatening unless you scrape the eye-wall or the storm begins to phase.

If anything the life-threatening impact from Irma if she stays far enough away (and on approach) is the incredibly high heat-index values. I can imagine model temp and humidity data push 110+ Heat Index values ahead. Dangerous stuff, esp when everyone goes about business as usual because a storm -may- turn away and forget its impacts already exists. (Heat, Surf).

[Weatherboy1]

Another look at the hard right turn before reaching SE Florida. Have to say, if it ends up doing something like that, talk about a nail biter and yet another lucky escape for a South Florida (and yet another not so lucky hit on the Bahamas). You can't rule it out but seems a bit suspicious especially looking at the ensembles:

. Yep. Very odd. Another view of the brick wall run, lol.

I think these "right angle" turns are highly suspect. A turn from WNW to NW to N is much more likely in my opinion. Question is, how close to the coast does that happen? Or could it happen inland? Still too far out to say. But gonna be some late nights here if this keeps up!

[Blinhart]

Another look at the hard right turn before reaching SE Florida. Have to say, if it ends up doing something like that, talk about a nail biter and yet another lucky escape for a South Florida (and yet another not so lucky hit on the Bahamas). You can't rule it out but seems a bit suspicious especially looking at the ensembles:

. Yep. Very odd. Another view of the brick wall run, lol.

Wonder what NHC is going to say with these models basically stopping in 5 days? I think that is pretty much what these models are saying.

[SapphireSea]

Another look at the hard right turn before reaching SE Florida. Have to say, if it ends up doing something like that, talk about a nail biter and yet another lucky escape for a South Florida (and yet another not so lucky hit on the Bahamas). You can't rule it out but seems a bit suspicious especially looking at the ensembles:

I think these "right angle" turns are highly suspect. A turn from WNW to NW to N is much more likely in my opinion. Question is, how close to the coast does that happen? Or could it happen inland? Still too far out to say. But gonna be some late nights here if this keeps up!

Storms can turn on a dime figuratively. If steering collapses it will meander a few miles W, few miles N, few miles E, few miles S etc in small loops. We saw this with Matthew; most of the time if the influence of the ridge to the W of the storm is not strong enough and the E ridge stronger, it will meander and move generally NNE. I think the way the heights are presented still favor a stall and N-NNE motion chasing the trough before the possibility of a ridge bridging, or another catching it.

[toad strangler]

Let's just hope the consistent W shifts end or that hard right can be a knockout punch for FL

[northjaxpro]

Most models DO slow down Irma in that area too - that is terrible news for the Bahamas though. Almost like pulling a Joaquin.

Yeah that's what I thought of course in my years of analysis when they get this size I can't ever recall seeing a massive tropical cyclone making such a abrupt movement change like that image showed above. Yes, any slow down or near stall will be catastrophic in the Bahamas at the intensity that the models are showing it to be at that time so we will watch and just hope for the best scenario, but it's looking very very ominous that Irma is going to get very close to the Florida East Coast by next weekend.

My experience has been that if/when a storm stops, or slows waaay down, it's getting ready to make a change in direction. So if it were to stop, or slow considerably over the Bahamas, I would expect the very sharp northerly turn after that.

Correct.

[Aric Dunn]

We know why the models are turning sharp north. Its a ramdom mid to upper low that forms over the mississippi valley that lifts it north.. they are probably not
going to say nothing.. but like most its extremely unlikely