ATL: IRMA - Post-Tropical - Discussion

[WeatherEmperor]

Key point from Eric Blake in the discussion.

In addition, the strongest
members of the recent ensembles are on the southern side on the
consensus, giving some confidence in that approach.

This has been a trend for a couple days. The Euro ensembles that have had Irma as cat 4s and 5s have been the southern most tracks in the ensemble.

So basically the stronger Irma gets the more likely a southern route is to happen?


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[Aric Dunn]

Key point from Eric Blake in the discussion.

In addition, the strongest
members of the recent ensembles are on the southern side on the
consensus, giving some confidence in that approach.

This has been a trend for a couple days. The Euro ensembles that have had Irma as cat 4s and 5s have been the southern most tracks in the ensemble.

So basically the stronger Irma gets the more likely a southern route is to happen?


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the other way around.. the more south irma get the stronger she can become.

[Blinhart]

And she is now a Cat 3 with winds of 115, can see her staying South of the forecast points.

[La Sirena]

Wow....just got in from an appt and BOOM we're at Cat 3. I see the Euro is currently sticking to its guns on that Westerly/SW path.

[KWT]

Key point from Eric Blake in the discussion.

In addition, the strongest
members of the recent ensembles are on the southern side on the
consensus, giving some confidence in that approach.

This has been a trend for a couple days. The Euro ensembles that have had Irma as cat 4s and 5s have been the southern most tracks in the ensemble.

Yep ad now that this a major hurricane I think its probably a trend we need to watch closely. I'm thinking in general terms of a track roughly similar to Irene, maybe just a little north of Irene and slightly flatter. Floyd may also be a close track as well to what I'm thinking. I suspect an east coast threat rather than Florida/Gulf threat but plenty of time for changes still and who knows it ma yet go OTS!

[tropicwatch]

Wow....just got in from an appt and BOOM we're at Cat 3. I see the Euro is currently sticking to its guns on that Westerly/SW path.

The NHC is leaning in that direction to according to the latest NHC Irma discussion.

[ConvergenceZone]

Unfortunately a cat 4/5 near the Leewards/Puerto Rico is becoming less of a potential and more of a likelihood. Still has time to shift some, but its never too soon to start preparing.

So you think that a cat 4 / 5 CANE is highly possible close to the Leewards?

Im not ready to go "highly likely" yet. A track, especially to the north still possible.

I got to hand it to you RL3AO, You nailed the impact of Harvey. You said the outcome would be a biblical natural disaster. Some scoffed at what you said, but you were 100% correct

[Aric Dunn]

For those of you that like to use the climatology websites.. I cant recall there ever being a category 5 east of the isalnds..?

[weathaguyry]

A lot of these analogs that are getting thrown around like Irene, Donna, and Gloria, makes me think that areas north of NC may be in the crosshairs of this, even if it gets pretty far west (Donna crossed Florida and still hit Long Island)

[djones65]

Hugo 1989 was a category 5 east of the Caribbean islands

[La Sirena]

Wow....just got in from an appt and BOOM we're at Cat 3. I see the Euro is currently sticking to its guns on that Westerly/SW path.

The NHC is leaning in that direction to according to the latest NHC Irma discussion.

I just saw that, too. This is certainly going to be interesting....I would hate to see it cross SFLA and run up in the gulf.

[jlauderdal]

Hurricane Irma Discussion Number 6
NWS National Hurricane Center Miami FL AL112017
500 PM AST Thu Aug 31 2017

Irma has become an impressive hurricane with intense eyewall
convection surrounding a small eye. Satellite estimates continue to
rapidly rise, and the Dvorak classifications from both TAFB & SAB
support an initial wind speed of 100 kt. This is a remarkable 50-kt
increase from yesterday at this time.

Microwave and satellite data suggest that an eyewall replacement
cycle could be starting. This isn't surprising given how small the
eye is, and will probably be the first of many eyewall cycles for
this hurricane. Overall, Irma should be in a low-shear environment
for several days, with the intensity controlled by eyewall cycles
and the moderately warm SSTs along the path. Thus the forecast
intensity is leveled off for the next 2 days. After the weekend,
Irma should be moving over much warmer water, with SSTs forecast to
be 29C at the end of the period. All indications are for Irma to be
strengthening by the end of the forecast period, with the NHC
prediction adjusted slightly upward from the previous one, in line
with the extremely low pressures forecast by the global and regional
hurricane models at that time.

Irma continues moving west-northwestward, now at about 10 kt.
There has been no change to the forecast philosophy, with the
hurricane likely to turn westward and west-southwestward over the
next few days due to a building ridge over the central Atlantic. At
long range, however, model guidance is not in good agreement on the
strength of the ridge, resulting in some significant north-south
differences in the global models. I am inclined to stay on the
southwestern side of the model guidance, given the rather consistent
forecasts of the ECMWF and its ensemble. In addition, the strongest
members of the recent ensembles are on the southern side on the
consensus, giving some confidence in that approach.


FORECAST POSITIONS AND MAX WINDS

INIT 31/2100Z 17.3N 34.8W 100 KT 115 MPH
12H 01/0600Z 17.8N 36.2W 105 KT 120 MPH
24H 01/1800Z 18.2N 38.3W 105 KT 120 MPH
36H 02/0600Z 18.3N 40.7W 105 KT 120 MPH
48H 02/1800Z 17.9N 42.9W 105 KT 120 MPH
72H 03/1800Z 16.8N 47.5W 110 KT 125 MPH
96H 04/1800Z 16.0N 52.0W 115 KT 130 MPH
120H 05/1800Z 16.5N 56.5W 120 KT 140 MPH

$$
Forecaster Blake

NHC not buying the GFS runs

Nope, they have been south of guidance since disco #1

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[KWT]

A lot of these analogs that are getting thrown around like Irene, Donna, and Gloria, makes me think that areas north of NC may be in the crosshairs of this, even if it gets pretty far west (Donna crossed Florida and still hit Long Island)

Certainly areas right up the US coast are still in the ballpark, especially if that upper high remains stubborn and only gives way at the last moment, 12z cMC may well go that route looking at it.

ps, I hadn't thought of Gloria, but may not be a bad call either.

[jlauderdal]

The NHC is showing a lot of respect to the Euro and its ensembles in their 5pm update


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They should, the gfs has been off track since yesterday and the future doesn't look correct with the ridge

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[msbee]

I would appreciate some of your expert opinions regarding the Northern Caribbean islands. Could that please be included in your comments whenever you can? because it has to pass us before it gets close to the USA.We in the islands would appreciate regular input on this.
Thanks so much

[gatorcane]

check the models threads. I uploaded image comparisons between GFS and Euro on Harvey hitting Texas so we can compare the long-range forecast. Amazing how off the GFS was on Harvey compared to the Euro.

[Snowman67]

For those of you that like to use the climatology websites.. I cant recall there ever being a category 5 east of the isalnds..?

According to this map, it shows one has.

https://weather.com/storms/hurricane/ne ... -history-0

Edit. It was Hugo in 1989

[OverlandHurricane]

For those of you that like to use the climatology websites.. I cant recall there ever being a category 5 east of the isalnds..?

Ivan?

[Blinhart]

What will be interesting is how much the wind field will grow once the first EWRC happens, because right now she is very small, 15 miles for hurricane and 80 miles for TS.

[KWT]

check the models threads. I uploaded image comparisons between GFS and Euro on Harvey hitting Texas so we can compare the long-range forecast. Amazing how off the GFS was on Harvey compared to the Euro.

Even with Irma the GFS went way too far NW too quickly, to be fair most of the models did but that is just a very small example of how small errors can happen.

Anyway I've gotta say I didn't think we would have major hurricane Irma today, who knows how strong it will be down the line, still wouldn't be shocked if it doesn't become a high 4 or low 5.