ATL: IRMA - Models

[capepoint]

I still have trouble believing that a storm this strong will turn on a dime. A more rounded turn would carry it further west and expose more of Fla to the east eyewall.

[txwatcher91]

FWIW, a key piece of the puzzle seems to be the finger ridge extending across Florida and the energy in the Midwest. The Euro has a much stronger ridge, for longer, thus driving the storm further south and into Cuba before the turn begins. The GFS quickly breaks this ridging down due to the shortwave being stronger and initial HP weakening faster. In these scenarios I like to use the NAM for a synoptic setup; inside 48 hours it shows the much weaker finger ridge and although it’s not great with TC track it IS good with synoptic setups under 48 hours. This is why you see the early 00z guidance and 18z guidance mostly trending north and east. They are breaking that ridge down faster.

[Zarniwoop]

18Z HWRF run

Ugh.

I know we're too many days out to be exact, but as an ex-Florida resident, that makes me feel ill.

[gulfcoastdave]

For those in the panhandle west of apalachicola...
I would say at this point the model agreement is good that you will be on the west side of this storm. Yes, storms have missed the northeast turn like Katrina and Ivan, but that was 12 years ago. Models are arguably better. Not saying it won't happen, and the models still have time to change. it wouldn't take a "huge" swing to put Pensacola or even Alabama in play but its seeming less likely by the day. If I lived in Tallahassee I would be prepping. If I lived in Pensacola I'd be watching and make sure i have the pieces in place to move prep to completion quickly. Just my 2 cents and not a forecast...

I am watching as I am near Pensacola but have my daughter at FSU...I am watching to see if I need to have her leave on Friday. It will curious to see when the turn occurs.

[Javlin]

I just take issue with that right turn.I think of hurricanes as mass and it's in motion a cargo ship may take a mile or two to make a full turn.If Irma stalls then I can see it but either way it looks like FL takes a raking even if starts on the W Coast side first back E.

[MatthewsRevenge]

Remember for all those who think this will push east, this is still five days away. Either models will go back west by tomorrow night or we'll see a split between those pushing west and those pushing east and Florida will still be caught in the crossfire.

[ronjon]

Just looked at the CIMSS steering layers. A 962mb system will indeed track further west vs a sub 940mb system which will be further east. If this is true, then the GFS solution is not that crazy.

Is that todays steering? Undoubtedly will change the next 3-5 days.

[txwatcher91]

Remember for all those who think this will push east, this is still five days away. Either models will go back west by tomorrow night or we'll see a split between those pushing west and those pushing east and Florida will still be caught in the crossfire.

The energy that will cause this to make the turn is inside 84 hours and becoming better modeled. The east coast of FL is the most likely track imo, a Floyd analog looks very reasonable here still. When you have an excellent model like the NAM inside 48 hours that’s showing such a weak finger ridge... and then models start to trend towards that, it’s something to take note of and consider. The NAM is excellent at picking up patterns and changes inside 48 hours that other models simply miss or play catch up on.

Those questioning the hard right turn haven’t seen and experienced past hurricanes that did. It can, and does, happen if the pattern supports it. All models agree on the north turn it’s just a matter of how long before that happens.

[Dean4Storms]

I think the GFS is behind on that shortwave now seen here in imagery north of Montana in Canada......
https://atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+24

When you look at the forecast here, you see it way behind in time as the yellow area dropping down into the central US, it even pinches a piece rapidly SE which looks suspect to me...step it forward from 00 hours...GFS does not show it north of Montana till 36hr.
https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=us&pkg=pv330K&runtime=2017090518&fh=0

[MatthewsRevenge]

Remember for all those who think this will push east, this is still five days away. Either models will go back west by tomorrow night or we'll see a split between those pushing west and those pushing east and Florida will still be caught in the crossfire.

The energy that will cause this to make the turn is inside 84 hours and becoming better modeled. The east coast of FL is the most likely track imo, a Floyd analog looks very reasonable here still. When you have an excellent model like the NAM inside 48 hours that’s showing such a weak finger ridge... and then models start to trend towards that, it’s something to take note of and consider. The NAM is excellent at picking up patterns and changes inside 48 hours that other models simply miss or play catch up on.

Those questioning the hard right turn haven’t seen and experienced past hurricanes that did. It can, and does, happen if the pattern supports it. All models agree on the north turn it’s just a matter of how long before that happens.

IDK. GFS was quite terrible with Harvey last time... which is why some of us are wondering if this shortwave is really going to happen.

[Cflstorm]

In my humble opinion, after years of watching and learning, I do not believe that NHC will adjust in the 11 pm advisory because the Euro doesn't run until after midnight.

[Bocadude85]

Remember for all those who think this will push east, this is still five days away. Either models will go back west by tomorrow night or we'll see a split between those pushing west and those pushing east and Florida will still be caught in the crossfire.

The energy that will cause this to make the turn is inside 84 hours and becoming better modeled. The east coast of FL is the most likely track imo, a Floyd analog looks very reasonable here still. When you have an excellent model like the NAM inside 48 hours that’s showing such a weak finger ridge... and then models start to trend towards that, it’s something to take note of and consider. The NAM is excellent at picking up patterns and changes inside 48 hours that other models simply miss or play catch up on.

Those questioning the hard right turn haven’t seen and experienced past hurricanes that did. It can, and does, happen if the pattern supports it. All models agree on the north turn it’s just a matter of how long before that happens.

How do you explain the 18Z GFS ensemble mean that is significantly west of the OP run? When the ensembles don't agree with the op run that is usually a clue that there is something funky. Go through the GFS ensemble mean since 12z this morning..they have all been west of the op run. The NHC doesn't base their forecast off one model..they have other models available to them that are not available to the public.

[txwatcher91]

Remember for all those who think this will push east, this is still five days away. Either models will go back west by tomorrow night or we'll see a split between those pushing west and those pushing east and Florida will still be caught in the crossfire.

The energy that will cause this to make the turn is inside 84 hours and becoming better modeled. The east coast of FL is the most likely track imo, a Floyd analog looks very reasonable here still. When you have an excellent model like the NAM inside 48 hours that’s showing such a weak finger ridge... and then models start to trend towards that, it’s something to take note of and consider. The NAM is excellent at picking up patterns and changes inside 48 hours that other models simply miss or play catch up on.

Those questioning the hard right turn haven’t seen and experienced past hurricanes that did. It can, and does, happen if the pattern supports it. All models agree on the north turn it’s just a matter of how long before that happens.

IDK. GFS was quite terrible with Harvey last time... which is why some of us are wondering if this shortwave is really going to happen.

The shortwave is shown on all models, including the Euro. The timing is the difference, a faster and/or stronger one breaks the ridge down faster. A weaker or slower shortwave doesn’t. The GFS did very well with Harvey leading up to landfall as did the Euro. We will find out a lot more tomorrow once this is tracking north of Puerto Rico. If it’s really close to them then Euro will be right and if it’s further north then that gives weight to the GFS idea. All the models I’ve seen for the western coast of FL barely pass Irma north of Hispaniola and PR.

[invest man]

Just looked at the CIMSS steering layers. A 962mb system will indeed track further west vs a sub 940mb system which will be further east. If this is true, then the GFS solution is not that crazy.

Is that todays steering? Undoubtedly will change the next 3-5 days.

It will be interesting to see if Euro will initialize at the present pressure. Can't help but think that the depth of pressure has some kind of impact on track. Maybe since GFS runs twice to Euros 1 that it may take longer for it to catch up with current trends. Again wasn't it yesterday's Euro early run missing Hatteras to the east? My concern is the trend of U.K. It seemed pretty good last year in this area. However I'm just an amateur observer. IM

[Javlin]

Well us here along the NGOM are forecast to have lows in the 60's till Monday and I mean 61'62' if this happens I cannot see Irma getting that far in the GOM.

[txwatcher91]

Remember for all those who think this will push east, this is still five days away. Either models will go back west by tomorrow night or we'll see a split between those pushing west and those pushing east and Florida will still be caught in the crossfire.

The energy that will cause this to make the turn is inside 84 hours and becoming better modeled. The east coast of FL is the most likely track imo, a Floyd analog looks very reasonable here still. When you have an excellent model like the NAM inside 48 hours that’s showing such a weak finger ridge... and then models start to trend towards that, it’s something to take note of and consider. The NAM is excellent at picking up patterns and changes inside 48 hours that other models simply miss or play catch up on.

Those questioning the hard right turn haven’t seen and experienced past hurricanes that did. It can, and does, happen if the pattern supports it. All models agree on the north turn it’s just a matter of how long before that happens.

How do you explain the 18Z GFS ensemble mean that is significantly west of the OP run? When the ensembles don't agree with the op run that is usually a clue that there is something funky. Go through the GFS ensembles since 12z this morning..they have all be west of the op run. The NHC doesn't base their forecast off one model..they have other models available to them that are not available to the public.

Ensemble means are great tools outside 120 hours but OP runs are a little better inside that mark, imo. The Euro was way west of its ensemble mean, as well, so by the same reasoning it should be discounted Yes the ensembles are west of the OP for the GFS but that doesn’t necessarily mean it’s right, or wrong. I’ve seen many of these storms over the years that are forecast to make a hard right turn and usually it occurs faster and sooner than anticipated. Also, I explained why the OP run has added weight since the NAM synoptic setup concurs with the GFS and the 18z HWRF also made a significant north shift through most of its run to match that also. There is plenty of time for further adjustments but the east of Florida track is what I’ve thought would happen all along and I’m sticking with it, along with my Floyd 99 analog.

[Bamagirl2408]

Well us here along the NGOM are forecast to have lows in the 60's till Monday and I mean 61'62' if this happens I cannot see Irma getting that far in the GOM.

Hey- in Mobile its just Wed-Fri. 62-68 degrees on 7 day but yes. Definately coming tomorrow night on forecast.

[SFLcane]

 https://twitter.com/Wxmanms1/status/905251461285675008

[Digital-TC-Chaser]

00Z plots - quite a number of models have shifted east. Note Euro is not on this plot. Look closely: TVCN (consensus track) is just east of Florida:

[Michele B]

I just take issue with that right turn.I think of hurricanes as mass and it's in motion a cargo ship may take a mile or two to make a full turn.If Irma stalls then I can see it but either way it looks like FL takes a raking even if starts on the W Coast side first back E.

You can see the storm does stall at the southern tip of FL before making the turn.

That clip above goes very fast, so it's hard to see, but if you watch it, it looks like the storm just quits moving for about 6 hours, or maybe 9, I couldn't actually time it - it's going too fast.

It CAN turn, if it stops like that for that many hours. I hope NOT, as that will bring it right up and into my back yard, but I do see how it can make that abrupt turn....I don't like it, but I can see it.