ATL: IRMA - Post-Tropical - Discussion

[tolakram]

As far as surge and damage, I figured it would be a lot like Ike, with a spread out windfield capable of doing a lot of moderate damage to a wide area. Personally I didn't even consider the surge issue, and I can't find if there were any surge forecasts for places like Jacksonville or not.

Ike counts as "moderate" surge? I was under the impression the surge damage from Ike was really bad (at least when I was in Galveston afterwards basically everything up to the first stories of buildings was gutted and there were boats and walls of debris piled on the highway). The only saving grace of Ike's surge was it was focused on the Bolivar Peninsula instead of going up the Houston Ship Channel. But Bolivar was completely wiped clean.

As far as computer models go it's not possible to reduce it to "let's go with this model over this one." As I have said before, numerical physics simulations can only be a guide, and so someone has to call it somewhere.

No, I was unclear above. I was talking moderate wind damage to a wide area rather than concentrated horrific wind damage. I didn't know what to expect for surge other than what the NHC and NWS forecast. Ike was in a bowl, Irma was swirling around a peninsula. I should have figured it would be bad based on those images from the Bahamas of shallow bays devoid of water, but it just didn't dawn on me that the east coast would experience anything significant. Someone was saying Miami was fairly immune to storm surge based on the ocean topology, and the surge maps seemed to bear this out.

I'm not a met, or a physicist, but I do thing the equation is solvable ... just need more inputs and processing power.

[decgirl66]

North Brevard County checking in. Lost power from 9pm last night till about 7am this morning. Crazy night hearing the winds and rain, and not being able to see. We lost lots of limbs on our big oak tree and had one busted window in our sun room, but we are all alive and well! I vote we cancel the rest of this season!

[RL3AO]

Here are the NHC track errors for Irma. They're sorted small to large and aren't in chronlogical order. Most of the larger errors occurred when Irma had just formed and when Irma neared Florida. Only a small percentage of the errors were outside the cone. On average, 33% of all forecast points go outside the cone.

[EquusStorm]

Has been pretty laid-back so far north of Birmingham. Been raining all day, alternating between drizzle and moderate rain, but wind has been very mild so far, barely gusting over 25 or so. No real risk of flooding locally and our wind risk has been decreased. Power outages shouldn't be too big of a risk this far west if Irma's core keeps weakening, but I suspect the wind will pick up a bit nevertheless as the core passes north of us. Rain is likely to taper off with that big dry slot on the SW side that's coming up in a few hours.

What IS interesting is the temperature - it's been in the 50s all day and we are likely to set minimum high records all throughout the northern part of AL.

[p1nheadlarry]

Spared mostly from Irma. South of US 98 has some road closures but nothing major. Irma paralleling the west coast would have been a bad scenario for us but it went inland east of the forecast track. Spared this time, but also knowing what 2017 has done still watching. CFS showing pretty favorable conditions for October, and some of the forecast setups I've seen are concerning for Florida.

[cfltrib]

Checking in from extreme southwestern North Carolina. We've had on and off light to moderate rain since daybreak. Light wind from the east-southeast through the afternoon. Heavier gust started at 9 pm, but not all that strong. I'd estimate 20-30 mph.
About 80% of friends and family lost power in central Florida last night, but no major damage.

[nascarfan999]

On our local TV News this evening, their meteorologist showed comparative night pictures from space, of roughly the south half of FL. One was I assume weeks or months ago, the other early this a.m. Except maybe for Miami, it looked like freaking South Korea, or Japan, vs. North Korea, I tried to find the pics online but so far have not. The story is not on our station’s website. Can anyone find & post the pics?

I'm not sure if it is the same one, but here is one I saw today. Thanks for reminding me to post it.

 https://twitter.com/nsj/status/907286149986705416




"First look at power outages from one of @NOAASatellites' polar-orbiting birds. First image is "normal", second is post-Irma."

[wxman57]

I'm not sure what tropical characteristics Irma still hangs on to. Looking at the latest surface analysis, I see temps as low as 61F in the center of Irma.

Let's see:

1. Warm core? Nope
2. Organized convection around center? Nope
3. Strongest wind near center? Nope
4. Non-frontal? Nope

I figure the NHC doesn't want to confuse people by calling it post-tropical as they did with Sandy. However, they are now free to issue advisories on "post-tropical" (extratropical) storms.

It appears that Irma was transitioning to extratropical as it tracked up the Peninsula. The wind field nearly tripled in the process, and it lost its core of intense winds. That spared a smaller part of the Peninsula from intense wind damage but caused the whole peninsula to get moderate to strong TS winds with Cat 1 hurricane gusts. Less severe damage, but over a larger area. Plus, the larger wind field meant a much greater fetch for the onshore winds, increasing the setup tide along the east coast, leading to the flooding. All in all, quite a significant impact to the NE Caribbean, Florida, Georgia and S. Carolina. I'm ready for the season to end now...

[scogor]

Checking in from Sarasota. We relocated to a post-Andrew home with hurricane shutters (ours was built in 1985 and although we've made many renovations I did not feel comfortable riding out Irma in our home) about ten minutes north of us. Did not lose power at our safe house and we luckily did not lose power in our neighborhood. Extremely fortunate to have returned to our home earlier today to find numerous large tree limbs and branches in our yard (many close to our home itself) but no damage whatsoever to our home--pool cage untouched, satellite dish intact, etc...a few wood panels from our neighbor's fence collapsed on his side. Spent the rest of the day unpacking and returning our plants, pool furniture, etc. to their customary locations...very, very thankful--my mother-in-law lives in Jacksonville--lost power earlier today and I don't know whether it's been restored.

[ScottNAtlanta]

Weather in Charleston has been bad all day. Lots of storm surge, heavy rain, and winds easily gusting to50-60 mph. Hard to believe how far away the center is from us

[abajan]

A few minutes ago, the last public advisory on Irma was issued.

[stormreader]

A few minutes ago, the last public advisory on Irma was issued.

Great post!

[emeraldislenc]

How many days were Irma a storm!

[romeoblade]

A few minutes ago, the last public advisory on Irma was issued.

Good Riddance.

[cycloneye]

BULLETIN
Tropical Depression Irma Advisory Number 52
NWS National Hurricane Center Miami FL AL112017
1100 PM EDT Mon Sep 11 2017

...IRMA WEAKENS TO A TROPICAL DEPRESSION...
...HEAVY RAINFALL CONTINUES ACROSS THE SOUTHEASTERN UNITED STATES...


SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...32.4N 84.9W
ABOUT 5 MI...10 KM S OF COLUMBUS GEORGIA
ABOUT 95 MI...150 KM SSW OF ATLANTA GEORGIA
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 320 DEGREES AT 15 MPH...24 KM/H
MINIMUM CENTRAL PRESSURE...988 MB...29.18 INCHES

[1900hurricane]

How many days were Irma a storm!

Irma accumulated 12.75 Tropical Storm Days.

[Bunkertor]

I collected pics and vids
https://mega.nz/#!yBd0GD5b!rkD-lWrYwAgZ ... 3oUwMqTZiM

[Bunkertor]

I collected pics and vids on Irma. You can download them here:
https://mega.nz/#!yBd0GD5b!rkD-lWrYwAgZ ... 3oUwMqTZiM

[RL3AO]

Here are the NHC errors over time. All of the points outside the cone occurred early on in Irma's life.

[storm_in_a_teacup]

As far as surge and damage, I figured it would be a lot like Ike, with a spread out windfield capable of doing a lot of moderate damage to a wide area. Personally I didn't even consider the surge issue, and I can't find if there were any surge forecasts for places like Jacksonville or not.

Ike counts as "moderate" surge? I was under the impression the surge damage from Ike was really bad (at least when I was in Galveston afterwards basically everything up to the first stories of buildings was gutted and there were boats and walls of debris piled on the highway). The only saving grace of Ike's surge was it was focused on the Bolivar Peninsula instead of going up the Houston Ship Channel. But Bolivar was completely wiped clean.

As far as computer models go it's not possible to reduce it to "let's go with this model over this one." As I have said before, numerical physics simulations can only be a guide, and so someone has to call it somewhere.

No, I was unclear above. I was talking moderate wind damage to a wide area rather than concentrated horrific wind damage. I didn't know what to expect for surge other than what the NHC and NWS forecast. Ike was in a bowl, Irma was swirling around a peninsula. I should have figured it would be bad based on those images from the Bahamas of shallow bays devoid of water, but it just didn't dawn on me that the east coast would experience anything significant. Someone was saying Miami was fairly immune to storm surge based on the ocean topology, and the surge maps seemed to bear this out.

I'm not a met, or a physicist, but I do thing the equation is solvable ... just need more inputs and processing power.

Ah okay I guess I misunderstood you as saying the surge wasn't going to be bad.
As far the last sentence, that is correct. But that is of course where we're always lacking and so have to make compromises.