Major Hurricane Irma

[OSUmetstud]

1 minute ago, Windspeed said:

Irma's banding features came back strong last night. So much for my earlier thoughts that Irma might evolve into an annular donut. The moisture envelope around Irma looks pretty good now and what dry air exists in the mid levels to the north seems inconsequential or is moistening. There is a really nice band out in front of Irma that is firing out of that same environment.

Never been a huge fan of the annular thing.  I'd rather have a deep tropical cat 5 (Wilma, Gilbert, Mitch etc.) any day of the week than Isabel. 

[NJwx85]

Irma wasn't looking it's hottest a few hours ago, but seems to be recovering again. It might have ingested some drier air. 

[Hazey]

When you see global models depicting pressures of low 900's and high 800's consistently, for days, you don't discount. They all see a prime feeding ground for deep intensification. Especially the GFS. This has all the earmarks of becoming one badass cane.

[NJwx85]

2 minutes ago, OSUmetstud said:

Never been a huge fan of the annular thing.  I'd rather have a deep tropical cat 5 (Wilma, Gilbert, Mitch etc.) any day of the week than Isabel. 

Annular hurricanes are always interesting because we still don't truly understand how they form or why. Annular hurricanes also typically don't undergo ERC, so they can maintain higher intensities longer. I don't really see it making a big difference either way with Irma because the conditions once NW of Puerto Rico should be about as favorable as possible.

[NJwx85]

Just now, Hazey said:

When you see global models depicting pressures of low 900's and high 800's consistently, for days, you don't discount. They all see a prime feeding ground for deep intensification. Especially the GFS. This has all the earmarks of becoming one badass cane.

Please excuse this if it belongs in banter, but the same could have been said about the 50"+ amounts for Harvey which many people dismissed as overdone despite good model continuity and concencus.

[LibertyBell]

1 minute ago, NJwx85 said:

Please excuse this if it belongs in banter, but the same could have been said about the 50"+ amounts for Harvey which many people dismissed as overdone despite good model continuity and concencus.

And also the fact that Harvey was strengthening right up to landfall, Cat 4 landfalls are extremely rare.  It's one thing to see a Cat 4/5 in the middle of the ocean, quite another to see one making landfall.

[USCG RS]

Please excuse this if it belongs in banter, but the same could have been said about the 50"+ amounts for Harvey which many people dismissed as overdone despite good model continuity and concencus.

 

The problem becomes even up to ten years back, this type of overdoing was commonplace with models and the reductions were about 15-20% lower to compensate for this ( This comes from a discussion with a good friend of mine who works as a met and various classes over the years - for citation purposes). That being said, lately even some of the more extreme model predictions come up short. Mets, especially those who are from an older generation, are in an unprecedented time period, and one which they have not been prepared for. Anyway, that my two cents and humble opinion.

 

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[Akeem the African Dream]

Irma really dipping SW.  Models are probably going to need to keep adjusting south and west.

This could get pretty far west before having a significant turn northward

[Random Chaos]

11 minutes ago, NJwx85 said:

Annular hurricanes are always interesting because we still don't truly understand how they form or why. Annular hurricanes also typically don't undergo ERC, so they can maintain higher intensities longer. I don't really see it making a big difference either way with Irma because the conditions once NW of Puerto Rico should be about as favorable as possible.

From what I recall, annular hurricanes typically occur in less than ideal environments, generally lower SSTs and light shear. So I doubt we will see annular in Irma's case.

[bluewave]

10 minutes ago, Hazey said:

When you see global models depicting pressures of low 900's and high 800's consistently, for days, you don't discount. They all see a prime feeding ground for deep intensification. Especially the GFS. This has all the earmarks of becoming one badass cane.

That region has the warmest SST's along the storm track. It's also a spot where Irma will get a jet entrance region assist. So it make sense that the models deepen the hurricane most there.

 

 

[LibertyBell]

4 minutes ago, USCG RS said:

The problem becomes even up to ten years back, this type of overdoing was commonplace with models and the reductions were about 15-20% lower to compensate for this ( This comes from a discussion with a good friend of mine who works as a met and various classes over the years - for citation purposes). That being said, lately even some of the more extreme model predictions come up short. Mets, especially those who are from an older generation, are in an unprecedented time period, and one which they have not been prepared for. Anyway, that my two cents and humble opinion.

 

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This is exactly why I don't believe in "climo."  How much of this is anthropogenic-induced isn't even the point (although big precip events are on the increase), the point is that the climate isn't static and has never been.  Actually nothing in nature or the universe is static (not even at absolute zero- helium is still a liquid at that temp!)  What was "climo" 50 years ago isn't "climo" today and won't be "climo" 50 years from now.

[LibertyBell]

2 minutes ago, bluewave said:

That region has the warmest SST's along the storm track. It's also a spot where Irma will get a jet entrance region assist. So it make sense that the models deepen the hurricane most there.

 

 

Thanks, Chris, the point about the jet entrance region assist is an important one, because we have seen plenty of times that when TC crossed over very warm SST they didn't get as energized as we thought they would.

[Windspeed]

Annular hurricanes are always interesting because we still don't truly understand how they form or why. Annular hurricanes also typically don't undergo ERC, so they can maintain higher intensities longer. I don't really see it making a big difference either way with Irma because the conditions once NW of Puerto Rico should be about as favorable as possible.

 

 

Well it is certainly hard to predict but there does seem to be a connection to a moderately dry enough environment in the mid levels to suppress the development of strong convective banding. And though they do typically hold their eyewall structures longer due to negligible outter banding or an absence of banding convection, they seem to initially need a large ERC to form a large eyewall and reach some kind of state of equilibrium. Perhaps Irma's moisture envelope is just too pronounced for this to occur and a bad prediction by yours truly.

[SN_Lover]

GFS out to hour 18. Not much change. 

[weatherboy80]

Actually slightly north through 36-48h ...

[salbers]

Has it been mentioned that it is a separate piece of energy that becomes the cutoff pulling Irma west, after the higher amplitude trough lifts out. This piece is presently west of Northern California, so would be interesting to track its consistency with short term dprog/dt plots and with satellite data.

[LandofLincoln]

6 minutes ago, weatherboy80 said:

Actually slightly north through 36-48h ...

Not really.

[Hazey]

Please excuse this if it belongs in banter, but the same could have been said about the 50"+ amounts for Harvey which many people dismissed as overdone despite good model continuity and concencus.

Good point hence maybe those insanely low pressures are not that far fetched. We'll see.

[weatherboy80]

2 minutes ago, LandofLincoln said:

Not really.

Correct - More or less the same through 72

[Vice-Regent]

9 minutes ago, weatherboy80 said:

Actually slightly north through 36-48h ...

I suspect the cutoff ULL may drag Irma East of the 6z positioning before resuming a NW trajectory. Even on visible satellite it looks to be heading a shade north of W. We are still in the game for sure.

[SnoSki14]

Irma's eventual size is what worries me, we could be looking at a disasterous and widespread storm surge over some very vulnerable real-estate and our resources are already stretched thin. 

There will still be flooding in Texas if/when Irma hits land. 

[SN_Lover]

PR might get some effects the way these trends are going. Ridge to the North stronger this run than 6z. 

[LibertyBell]

2 minutes ago, SnoSki14 said:

Irma's eventual size is what worries me, we could be looking at a disasterous and widespread storm surge over some very vulnerable real-estate and our resources are already stretched thin. 

There will still be flooding in Texas if/when Irma hits land. 

We might have to look at nontropical comparisons just because of sheer size.  Ash Wednesday 1962 and Dec 1992 come to mind.

[larrye]

38 minutes ago, NJwx85 said:

Please excuse this if it belongs in banter, but the same could have been said about the 50"+ amounts for Harvey which many people dismissed as overdone despite good model continuity and concencus.

No one's discounting the pressures that the models are forecasting. Only that they are likely overdone. The way I see it, the Harvey situation is different because it was caused by a stall and some kind of blocking or lack of steering. Could there be a hurricane that is deeper in pressure than anything seen before? Sure. Just like there can be a record low or high temperature for a location that's never been seen before. But in attempting to forecast, you take the norms/odds of an anomaly into consideration.

[packfan98]

The SW trend continues on the gfs thus far through hr 108.

[Random Chaos]

Z500 looks nearly identical as the last two GFS runs.

[StormFollowerUSA]

To me based from NHC and Accuweather this is looking like a Florida Lamdfall


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[SN_Lover]

I think it's safe to say the odds of a OTS storm are diminishing. Correct me here, but it appears all the CONUS players are onshore now. Might change in the future, but that's where things stand now. 

[DopplerWx]

yea a tick sw this run, and stronger thru 126

[Wow]

watch that little piece of energy coming right behind the trough over the N Plains at 120.. that could be a big player here if the trough bypasses entirely.