ATL: IRMA - Post-Tropical - Discussion

[KBBOCA]

Latest update from NWS Key West.

Extreme wind threat.
Extreme storm surge threat.



 https://twitter.com/NWSKeyWest/status/905933005759414272

[Steve]

Is it a bit irresponsible for this promet to be posting this?

it feels a bit hyperbolic

@RyanMaue
Based on size of Hurricane #Irma + Category 4/5 landfall winds/surge & track up I-75 to Atlanta, are we contemplating a Trillion $ disaster?

Wing nut and hype media. He should be better than that. Call attention to the storm, not click bait for your Twitter. Trillion dollars is beyond preposterous.

[Extratropical94]

917.8 extrapolated, but keep in mind that we've already had 7 mb errors with these readings.

[Michele B]

Is it a bit irresponsible for this promet to be posting this?

it feels a bit hyperbolic

@RyanMaue
Based on size of Hurricane #Irma + Category 4/5 landfall winds/surge & track up I-75 to Atlanta, are we contemplating a Trillion $ disaster?

Yes, I quibble a lot with Ryan Maue's tweets. Most of his info is sound, but he does go for the sensationalist approach at times. Sadly with Irma, most of his sensationalism early on proved right on target, so I've downplayed my criticism of him.

But I agree with you, this latest tweet seems over done.

Jury's still out. He may be right on this one.

[Sciencerocks]

000
URNT15 KNHC 072336
AF309 1811A IRMA HDOB 18 20170907
232630 2052N 07125W 6967 02842 9658 +131 +089 209088 090 091 010 00
232700 2053N 07126W 6963 02823 9626 +142 +090 212093 094 091 007 00
232730 2054N 07128W 6964 02799 9593 +151 +087 213097 099 089 007 00
232800 2055N 07129W 6969 02776 9585 +137 +090 213101 103 086 003 00
232830 2056N 07131W 6965 02754 9559 +136 +087 212104 105 087 000 00
232900 2057N 07132W 6967 02724 9524 +142 +082 212109 110 088 000 00
232930 2058N 07133W 6966 02690 9477 +151 +081 212114 116 093 000 03
233000 2100N 07135W 6965 02650 9430 +152 +096 214116 117 097 000 00
233030 2101N 07136W 6965 02597 9382 +144 +103 213120 120 100 002 00
233100 2102N 07137W 6957 02545 9341 +120 +116 211109 120 102 004 00
233130 2103N 07139W 6975 02479 9276 +138 +111 213083 097 100 003 03
233200 2104N 07140W 6961 02461 9219 +164 +112 213060 074 077 004 00
233230 2105N 07142W 6970 02435 9188 +180 +103 213037 052 054 002 00
233300 2106N 07144W 6966 02429 9187 +172 +106 217016 030 031 001 03
233330 2107N 07145W 7006 02371 9178 +176 +106 217001 011 019 000 00
233400 2108N 07147W 6957 02432 9178 +171 +101 060010 014 016 001 00
233430 2109N 07148W 6967 02420 9187 +164 +109 056018 021 019 002 00
233500 2111N 07149W 6965 02429 9195 +161 +109 063027 030 029 002 00
233530 2112N 07151W 6964 02439 9203 +160 +107 064037 041 034 002 00
233600 2113N 07152W 6969 02444 9219 +158 +101 056047 051 045 001 00
$$
;

This part of the eye wall appears to be quite weak! Only cat3 winds.

[NDG]

SE quadrant definitely weaker but that's where is missing an inner eyewall, pressure remains low.

232930 2058N 07133W 6966 02690 9477 +151 +081 212114 116 093 000 03
233000 2100N 07135W 6965 02650 9430 +152 +096 214116 117 097 000 00
233030 2101N 07136W 6965 02597 9382 +144 +103 213120 120 100 002 00
233100 2102N 07137W 6957 02545 9341 +120 +116 211109 120 102 004 00
233130 2103N 07139W 6975 02479 9276 +138 +111 213083 097 100 003 03
233200 2104N 07140W 6961 02461 9219 +164 +112 213060 074 077 004 00
233230 2105N 07142W 6970 02435 9188 +180 +103 213037 052 054 002 00
233300 2106N 07144W 6966 02429 9187 +172 +106 217016 030 031 001 03
233330 2107N 07145W 7006 02371 9178 +176 +106 217001 011 019 000 00
233400 2108N 07147W 6957 02432 9178 +171 +101 060010 014 016 001 00
233430 2109N 07148W 6967 02420 9187 +164 +109 056018 021 019 002 00
233500 2111N 07149W 6965 02429 9195 +161 +109 063027 030 029 002 00
233530 2112N 07151W 6964 02439 9203 +160 +107 064037 041 034 002 00

[SEASON_CANCELED]

turnpike is overwhelmed. would advise to use back roads

I love the back roads for evacuations. Used them to get far from Jacksonville/Matthew last year (and back). They're generally empty, more peaceful, and you get to see new sights.

There are (going by drudge) thousands of cars abandoned because they ran out of gas on the pike

Not confirmed

[SkeetoBite]

If it goes up the spine, Orlando wouldn't get devastating winds would it? We just moved from there and have a fair number of friends I need to start working on if this is predicted to hold together bizarrely well over land.

So, I think you should be prepared for significant winds in Orlando. NHC graphic to follow as soon as I find it.

Here's the latest windspeed probabilities from NHC.
http://www.nhc.noaa.gov/text/refresh/MI ... 2058.shtml

If I'm reading it correctly, 63% cumulative percent chance of sustained winds of 58 MPH; 42% cumulative probability of winds 74 MPH.

Also, look at your forecast office (Melbourne FL). They have a graphical weather forecast which shows you the risks ahead. It takes a bit of playing with to figure out, but here's Sunday night wind gusts:
https://graphical.weather.gov/sectors/mlb.php

For Sunday night, gusts in Orlando could reach 89 knots (102 MPH)!

To make these images more useful; convert KTS to MPH by Multiplying knots by 1.151

[Aric Dunn]

pressure is down a few mB for sure.. need the dropsonde though..

[Kingarabian]

Doesn't look like a cat.5 anymore. I know it's the weaker side but the winds are barely 120kts -- unless im missing something.

[AdamFirst]

Sitting back and watching some football, as this is probably one of the last normal days we got.

Gotta help prep my job tomorrow for the storm.

[CrazyC83]

For those who don't want to evacuate: you may not get help from the north for several days.

Florida is a peninsula. With the only land routes to the north, they will have to come that way. Problem is that the storm is going in that direction and will remain dangerous at least through Monday or Tuesday. FEMA and private aid will NOT drive through hurricane conditions, so that means outside help may not come until midweek even if they wanted to help sooner.

I'd suggest having at least 7-10 days worth of supplies if staying back, not just 72 hours.

[facemane]

Can someone please explain to me how this system is to turn right .. I mean can something this big just hit the brakes and turn right??

Absolutely it can. A strong cyclone tends to move poleward. A blocking high pressure ridge to the north is the reason they move west or northwest in the Atlantic basin. If the ridge get's weakened,the storm will seek it out and move more north.

[Extratropical94]

SE quadrant definitely weaker but that's where is missing an inner eyewall, pressure remains low.

232930 2058N 07133W 6966 02690 9477 +151 +081 212114 116 093 000 03
233000 2100N 07135W 6965 02650 9430 +152 +096 214116 117 097 000 00
233030 2101N 07136W 6965 02597 9382 +144 +103 213120 120 100 002 00
233100 2102N 07137W 6957 02545 9341 +120 +116 211109 120 102 004 00
233130 2103N 07139W 6975 02479 9276 +138 +111 213083 097 100 003 03
233200 2104N 07140W 6961 02461 9219 +164 +112 213060 074 077 004 00
233230 2105N 07142W 6970 02435 9188 +180 +103 213037 052 054 002 00
233300 2106N 07144W 6966 02429 9187 +172 +106 217016 030 031 001 03
233330 2107N 07145W 7006 02371 9178 +176 +106 217001 011 019 000 00
233400 2108N 07147W 6957 02432 9178 +171 +101 060010 014 016 001 00
233430 2109N 07148W 6967 02420 9187 +164 +109 056018 021 019 002 00
233500 2111N 07149W 6965 02429 9195 +161 +109 063027 030 029 002 00
233530 2112N 07151W 6964 02439 9203 +160 +107 064037 041 034 002 00

The decayed part of the inner eyewall still has higher winds than the outer eyewall. Two wind maxima clearly visible on the last two datasets.

[Aric Dunn]

very distinct double wind maximum.

[1900hurricane]

Considering the current state of eyewall replacement, I still think we're 12-18 hours away from returning to a single eyewall with a clearing eye. The outer eyewall does appear to be gaining dominance on microwave imagery, but considering the large radius of the outer eyewall, it may take some time for it to fully kill of the inner eyewall.

I should also mention that eyewall replacement is still rather unpredictable, even as it is occurring. I've seen plenty of storms botch eyewall replacement for whatever reason and end up in a structural flux. I've also seen systems complete massive eyewall replacement projects in relatively short periods of time when I fully didn't expect it to even complete. Eyewall replacement has kicked my butt in the past, and I'm sure it will in the future. Whether it does here in this instance with Irma remains to be seen.

Putting you on the spot, an average time between ERC's for Cat 4's and 5's might be???? or is it something not that well understood?

I'd say about 24 hours, but it is something that has rather large variance. Some systems have pulled it off in as short a time as <12 hours, but there are others that can show little to no progression for multiple days and end up getting stuck with two relatively well formed concentric eyewall, which kills the pressure gradient in the core but also greatly increases wind radii. How to predict the duration of eyewall replacement ahead of time is a low skill affair though since there is still much we need to learn on the topic.

[KBBOCA]

A good NPR article with a pretty detailed round up of devastation caused by Irma to the Northern Leewards, British & US Virgin Islands & Puerto Rico
http://www.npr.org/sections/thetwo-way/ ... icane-irma

Thankfully the death toll seems to still be remarkably low given the immense physical destruction of so much property.

[NDG]

Doesn't look like a cat.5 anymore. I know it's the weaker side but the winds are barely 120kts -- unless im missing something.

The pressure has not gone up and it has not sampled the NW quadrant yet.

[Steve]

Come on Michelle. Lets be serious. If it hits 100B, it will be one of only two storms in history though we are still counting Harvey. If it hits 175B, it will be the only one. So multiply that times six.

People believe anything nowadays.

[hurricaneCW]

Doesn't look like a cat.5 anymore. I know it's the weaker side but the winds are barely 120kts -- unless im missing something.

Perhaps it's weaker but pressure is still very low and the majority of models showed some weakening over the next 24 hrs before restrengthening in the straits.