ATL: IRMA - Post-Tropical - Discussion

[CrazyC83]

One thing is for sure: it is nearly impossible to find and record Recon data when there are three storms going on at once with flights. I think they should use a separate header for each flight (maybe have 5 headers available).

[SoupBone]

Dr. M seems to find it unlikely Irma will ever regain Cat 5 intensity. He mentions it could even potentially weaken to a 3 from interaction with Cuba. At least a bit of good news there, as he was expecting Irma to ramp back up to 185 MPH Yesterday.

Link to this? If true and you're looking for at least something better, this is about all we're going to hear at this point. I really hope this holds true, but even a Cat 3 can be catastrophic in terms of damage and storm surge.

[Langinbang187]

Dr. M seems to find it unlikely Irma will ever regain Cat 5 intensity. He mentions it could even potentially weaken to a 3 from interaction with Cuba. At least a bit of good news there, as he was expecting Irma to ramp back up to 185 MPH Yesterday.

Link to this? If true and you're looking for at least something better, this is about all we're going to hear at this point. I really hope this holds true, but even a Cat 3 can be catastrophic in terms of damage and storm surge.

https://www.wunderground.com/cat6/extremely-dangerous-cat-4-irma-headed-florida

He even says there's a 20% chance it could weaken to a 2.

[AutoPenalti]

Irma is about to encounter some very warm waters.

[p1nheadlarry]

That parameter doesn't steer it. It effects intensification.

How so, does it help with outflow, impart shear on the storm, etc?

It's not a wind map at all, but Theta-E relates to the instability of the atmosphere and potential for convective development (is that accurate as a quick explanation?)

Oh, ok. Still learnin' the ropes

[Bunkertor]

Ouch!
CAPE building up to 4000 in the Keys

this is one of my big concerns!

And not mentioned in the outlook

[GCANE]

Massive Flight Exodus out of FL

[p1nheadlarry]

Ouch!
CAPE building up to 4000 in the Keys

this is one of my big concerns!

Possibly part of the reason some models blow this up near land? In addition to the sauna of the straits..

[jdjaguar]

I'm sure many of you have used this resource before, but for those who are inland like myself, and who are still anxiously following forecast wind speeds, this tabular forecast is very helpful:

http://forecast.weather.gov/MapClick.php?w0=t&w1=td&w2=hi&w3=sfcwind&w3u=1&w4=sky&w5=pop&w6=rh&w7=rain&w8=thunder&w10u=0&w12u=1&w13u=1&AheadHour=0&FcstType=digital&textField1=28.3577&textField2=-82.6995&site=all&unit=0&dd=&bw=&AheadDay.x=60&AheadDay.y=6&AheadDay=48

Very useful. Thnx.

How do you plug in your location? Search box?

[Blown Away]

It's official, my shutter decision in Hobe Sound will be delayed pending 12z Euro run...

[Steve]

Dr. M seems to find it unlikely Irma will ever regain Cat 5 intensity. He mentions it could even potentially weaken to a 3 from interaction with Cuba. At least a bit of good news there, as he was expecting Irma to ramp back up to 185 MPH Yesterday.

Not that good of news. The direct quote is:

...recovery and re-intensify back to its former strength. I’m not expecting Irma to regain Category 5 status, particularly since part of its circulation is now over Cuba, and the core of the hurricane will come very close to the Cuban coast on Friday night and Saturday. Conditions are otherwise favorable for intensification through Sunday, with light wind shear less than 10 knots and very warm ocean waters near 30°C (86°F.) Irma is likely to be a large and very dangerous Category 3 or 4 hurricane with 115 – 140 mph winds when it makes landfall in the Florida Keys between 1 am and 7 am Sunday morning.

[Steve]

Dr. M seems to find it unlikely Irma will ever regain Cat 5 intensity. He mentions it could even potentially weaken to a 3 from interaction with Cuba. At least a bit of good news there, as he was expecting Irma to ramp back up to 185 MPH Yesterday.

Link to this? If true and you're looking for at least something better, this is about all we're going to hear at this point. I really hope this holds true, but even a Cat 3 can be catastrophic in terms of damage and storm surge.

https://www.wunderground.com/cat6/extremely-dangerous-cat-4-irma-headed-florida

He even says there's a 20% chance it could weaken to a 2.

I'll take that bet with anyone.

[Ntxw]

Possibly part of the reason some models blow this up near land? In addition to the sauna of the straits..

There is plenty of warm water temps and conditions for strengthening in the FL straits. It is just a matter what Cuba does to effect her (if any at all) at this point. High CAPE also means increase risk of tornadoes

[dukeblue219]

Very quickly tuning in. Is that an NHC forecast for a possible landfall at about 165mph?

No, that was a personal storm forecast.

edit - the previous poster has addressed it himself.

[Hurricane Andrew]

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

Major Hurricane Irma [11L]
Track, Intensity, and Impact [TI2] Guidance
15z, September 18, 2017
$$

Current Information (11am, NHC, 6hr trend in parenthesis)
Winds: 130kts / 150mph
Pressure: 927mb
Movement: WNW (285) at 14mph

Track
Irma will continue to move on a west-northwesterly heading over the next twenty-four or so hours, and the center may pass within just a couple miles of the Cuban coastline. Beyond twenty-four hours, Irma will begin to feel the influence of an upper-level trough located in the northeastern United States, and model guidance unanimously agrees that at some point, Irma will turn to the north. Model consensus is fairly high, although shifting, that Irma’s center will make landfall in southern Florida, before tracking on a north-northwesterly heading into Georgia. After that, the guidance diverges on the eventual fate of Irma’s remnants.

Uncertainty remains on several extremely important details. How close will Irma come to Cuba? When will Irma turn to the north? How much time will the storm have over the boiling hot waters of the Florida Straight? These are things that, unfortunately, we may not know a real answer to, beyond an estimate, until they happen.

Intensity
11am Friday [Current] - 130kts / 150mph
11am Saturday [+24] - 135kts / 155mph
(Landfall Intensity - 145kts / 165mph)
11am Sunday [+48] - 120kts / 135mph
11am Monday [+72] - 70kts / 80mph
11am Tuesday [+96] - 30kts / 40mph
11am Wednesday [+120] - 25kts / 30mph

If the track of Irma is somewhat uncertain, the intensity is doubly so. The storm maintained category five intensity for a record length of time, but weakened to a still-catastrophic category four early this morning while undergoing an eyewall replacement cycle, or EWRC. This EWRC appears to be complete, and the model consensus shows pressures ceasing to rise by later tonight, and dropping during the day Saturday and all the way up until landfall. The next forty-eight hours will bring Irma’s core over an area of extremely high ocean heat content, with sea surface temperatures ranging from 30 to 32 degrees celcius. Shear will be minimal until landfall, and dry air should not have an impact until after the +48 forecast period.

The only factor that I can see keeping a lid on Irma is a major one; land interaction. Should the hurricane actually make landfall in Cuba, it is possible it may weaken further, perhaps to a category three hurricane. It will then have twelve to eighteen hours over the Florida Straight, more than enough time to regain strength should any further EWRCs fail to materialize. It is worth noting that should the models shift even further west, additional time will be allotted to this hurricane to strengthen, if only a few hours, an effect that would likely be offset by increased land interaction.

Even a category three landfall will have devastating effects across southern Florida. Hurricanes Katrina, Rita, and Wilma were category three storms at their time of landfall. Category four strikes include Hugo, Charley, and Ivan. For an example of category five effects, look at Andrew, or even Irma’s own effects in the Lesser Antilles.

Make no mistake, this storm will have an extreme effect, no matter if it landfalls as a three, a four, or a five. Irma’s size has increased drastically over the past two days, and nearly all of the Florida Peninsula can be expected to experience hurricane force gusts at a minimum.

Impact
Hurricanes have many different impacts, all deadly and heavily damaging, including heavy rain, storm surge flooding, high winds, conventional severe weather, and overall infrastructural damage. Below are summaries for three different zones. Note that these zones can change at any time before and during the event, and this should NOT be used as an evacuation guide.

EXTREME IMPACT
Sustained winds of 100-130mph, with higher gusts.
Heavy coastal flooding from storm surge, especially on the western coast. Flooding may be accentuated by heavy waves.
Rainfall totals of ten or more inches, with hourly rates of one to two inches or higher possible during the peak of the storm.
Flash flooding and street flooding is possible to likely, especially in places with poor drainage, as well as low-lying areas and known flood zones.
Widespread, extended power outages are all but inevitable.
Many areas will be impassable for days or even weeks, especially closer to the coast. Some areas may become uninhabitable for an extended period of times.

SEVERE IMPACT
Sustained winds of 70-100mph, with higher gusts, especially in the southern and eastern portions of the zone.
Significant coastal surge flooding, especially on the western coast. Flooding may be accentuated by heavy waves.
Rainfall totals of six or more inches, with hourly rates of one to two inches or higher possible during the peak of the storm.
Flash flooding and street flooding is possible, especially in places with poor drainage, as well as low-lying areas and known flood zones.
Widespread power outages are likely, and power may remain out for an extended period of time.
Many areas will be impassable for days due to debris, standing water, etc.

SIGNIFICANT IMPACT
Sustained winds of 40-70mph, with higher gusts possible, especially of Irma retains her strength further inland than expected.
Moderate coastal surge flooding is possible in coastal areas, along with heavy wave action.
Rainfall totals of six or more inches, with hourly rates of one to two inches or higher possible during the peak of the storm.
Flash flooding and street flooding is possible, especially in places with poor drainage, as well as low-lying areas and known flood zones.
Scattered to widespread power outages are possible, and power may remain out for several days.


Notes
Emergency response will be hindered, if not rendered impossible, both during and after the event throughout much of eastern and southern Florida. If you haven’t evacuated and want to do so, the time is NOW! Every hour, this storm moves closer to landfall.
Focusing on an exact track is pointless; the swath of hurricane force winds is well over a hundred miles wide, and the swath of tropical storm force winds is triple that. No matter where Irma makes landfall, most of the state will see significant to major effects.
Should Irma make landfall as a category five, the wind and infrastructural impacts in the “EXTREME” zone may be higher than stated above. At this point, residents of southern and southeastern Florida should expect a crippling strike.
This storm is an imminent threat to life. Get out, or get safe.

Can't figure out how to upload an image...imageshack is no longer free.

I wonder if Irma is going onshore of Cuba and struggles to get off the coast for 12-20 hrs. this could possible take her down to Cat 2 or weaker. Hopefully not to recover. Weaker storms tend to move more westerly as well. Possible good news for Miami, not so good for Cuba. Prayers for all involved.

Very quickly tuning in. Is that an NHC forecast for a possible landfall at about 165mph?

No sir, that is my personal forecast. Current NHC forecast, and remember that they have so many more worlds of skill than me, calls for a 145mph landfall. They are the experts, not me. Please remember that.

[Jeffross]

Irma will miss Cuba before this beautiful beast makes landfall on South Florida

[GCANE]

Core about 2 hrs ago.
Massive lapse rate from surface / boundary layer to 600mb.
Looks like its ready for another round, just needs a little juice.

[Hurricane Andrew]

Very quickly tuning in. Is that an NHC forecast for a possible landfall at about 165mph?

No, that was another poster's personal storm forecast. I was concerned people might view it as official the way it was written.

I put in the disclaimer, I apologize for any confusion. Also, Jose is now a cat 4.

[Kenderkin17]

Yeah, it's sad to say but Jose is looking more impressive than Irma right now in terms of presentation. This of course is due to his location over open water, but the scary part is that he is as strong as she is now, and showing signs of more intensification.

Sad to say in that there is another monster of a storm which may threaten land.

[norva]

Dr. M seems to find it unlikely Irma will ever regain Cat 5 intensity. He mentions it could even potentially weaken to a 3 from interaction with Cuba. At least a bit of good news there, as he was expecting Irma to ramp back up to 185 MPH Yesterday.

Link to this? If true and you're looking for at least something better, this is about all we're going to hear at this point. I really hope this holds true, but even a Cat 3 can be catastrophic in terms of damage and storm surge.

https://www.wunderground.com/cat6/extremely-dangerous-cat-4-irma-headed-florida

He even says there's a 20% chance it could weaken to a 2.

I can't even fathom it dropping to a 2 unless it slams into Cuba and stays a while. If I were a betting man I would say high 4/5 is the most likely. It just depends on how much Cuba disrupts it.