ATL: IRMA - Post-Tropical - Discussion

[Kingarabian]

Looks like Irma is quietly doing an Eyewall Replacement Cycle. Irma's eye and windfield would likely expand once it's finished.

[img]https://www.nrlmry.navy.mil/tcdat/tc17/ATL/11L.IRMA/gmi/89h/2degreeticks/20170901.0546.gpm.x.89h.11LIRMA.100kts-967mb-175N-351W.40pc.jpg[/mg]

Can't be a major with that structure. I suspect the real Irma grand show will begin in 2-3 days when it's east of the islands.

[Digital-TC-Chaser]

I would estimate on the inner core brightness ring on this micro 95/100kt storm.

[Nightwatch]

she already looks like a monster to me. I wonder what it will bring

[mrbagyo]

[northjaxpro]

Irma's inner core structure is gradually getting better as of this early morning hour. It is beginning to get that deep convection wrapping around the eye.

I would estimate at least 100 kts currently. Irma is a very intense, well organized tropical cyclone for sure!!

[WeatherGuesser]

Hurricane Irma Advisory Number 8
NWS National Hurricane Center Miami FL AL112017
500 AM AST Fri Sep 01 2017

...IRMA HOLDING STEADY WITH 115-MPH WINDS...


SUMMARY OF 500 AM AST...0900 UTC...INFORMATION
----------------------------------------------
LOCATION...18.2N 36.5W
ABOUT 840 MI...1350 KM WNW OF THE CABO VERDE ISLANDS
ABOUT 1665 MI...2680 KM E OF THE LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WNW OR 300 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...967 MB...28.56 INCHES


WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
At 500 AM AST (0900 UTC), the center of Hurricane Irma was located
near latitude 18.2 North, longitude 36.5 West. Irma is moving
toward the west-northwest near 12 mph (19 km/h). A turn toward the
west is expected by tonight, followed by a turn toward the
west-southwest on Saturday.

Maximum sustained winds remain near 115 mph (185 km/h) with higher
gusts. Irma is a category 3 hurricane on the Saffir-Simpson
Hurricane Wind Scale. Fluctuations in strength, up or down, are
possible during the next few days, but Irma is expected to
remain a powerful hurricane through the weekend.

Hurricane-force winds extend outward up to 15 miles (30 km) from the
center, and tropical-storm-force winds extend outward up to 90 miles
(150 km).

The estimated minimum central pressure is 967 mb (28.56 inches).


HAZARDS AFFECTING LAND
----------------------
None


NEXT ADVISORY
-------------
Next complete advisory at 1100 AM AST.

[WeatherGuesser]

Hurricane Irma Discussion Number 8
NWS National Hurricane Center Miami FL AL112017
500 AM AST Fri Sep 01 2017

After rapidly strengthening on Thursday, Irma appears to have
leveled off in intensity. The eye of the hurricane remains
evident in satellite images, but it has occasionally been cloud
filled. The deep convection in the eyewall has been fairly
symmetric, and the Dvorak CI-numbers from TAFB and SAB have held
steady at 5.5/102 kt. Based on these data, the initial wind
speed remains 100 kt for this advisory.

Although Irma is in a very low wind shear environment, the hurricane
is moving over only marginally warm SSTs and is in close proximity
to dry air. The models respond to these conditions by showing
little change in strength or some weakening during the next couple
of days. Thereafter, Irma is expected to move into a more favorable
thermodynamic environment while remaining in low wind shear
conditions, which should allow the hurricane to intensify. It
should be noted that major hurricanes like Irma often undergo
eyewall replacements that can cause fluctuations in strength, but
unfortunately these internal dynamics can not be forecast with any
accuracy. The NHC intensity forecast is identical to the previous
one and lies near the high end of the model guidance.

Irma is moving west-northwestward at 10 kt to the south of a
subtropical high pressure system. This high is forecast to
strengthen and build westward during the next few days, which
should cause the hurricane to turn to the west in about 24 hours and
then move to the west-southwest over the weekend. By the end of the
forecast period, Irma is expected to move on the south side of the
high, which should cause the storm to turn back to the west or
west-northwest. Although the models agree on this overall scenario,
they differ slightly on the strength and orientation of the high and
the intensity of Irma. These differences have caused a fair amount
of north-south spread. The NHC intensity forecast lies near the
middle of the guidance envelope through day 4, but leans toward the
southern end at day 5, in favor of the ECMWF and HCCA models.

FORECAST POSITIONS AND MAX WINDS

INIT 01/0900Z 18.2N 36.5W 100 KT 115 MPH
12H 01/1800Z 18.5N 38.2W 100 KT 115 MPH
24H 02/0600Z 18.4N 40.5W 100 KT 115 MPH
36H 02/1800Z 18.2N 42.9W 100 KT 115 MPH
48H 03/0600Z 17.6N 45.2W 105 KT 120 MPH
72H 04/0600Z 16.5N 49.3W 110 KT 125 MPH
96H 05/0600Z 16.5N 53.5W 115 KT 130 MPH
120H 06/0600Z 17.5N 58.0W 120 KT 140 MPH

$$
Forecaster Cangialosi

[Bizzles]

Obviously still a far far away but when can we expect to start seeing recon missions?

[wxman57]

Obviously still a far far away but when can we expect to start seeing recon missions?

Probably no recon (manned) until next Tuesday at the earliest, once it's west of 50W. I would think that the Global Hawk would be flying missions before then.

I've noticed that the Euro has tended to be too far left/south this season (Cindy/Harvey as examples), while the GFS/CMC have tended to recurve too early. Actual track has tended to be in between the two, generally closer to the Euro than the GFS/CMC. Interesting that the overnight Euro recurves east of the U.S. Way too early to be confident in that. I think a SE U.S. hit is quite possible. Maybe 30-40% chance of Irma entering the Gulf.

[Bizzles]

Gotcha thanks!

[stormreader]

Obviously still a far far away but when can we expect to start seeing recon missions?

Probably no recon (manned) until next Tuesday at the earliest, once it's west of 50W. I would think that the Global Hawk would be flying missions before then.

I've noticed that the Euro has tended to be too far left/south this season (Cindy/Harvey as examples), while the GFS/CMC have tended to recurve too early. Actual track has tended to be in between the two, generally closer to the Euro than the GFS/CMC. Interesting that the overnight Euro recurves east of the U.S. Way too early to be confident in that. I think a SE U.S. hit is quite possible. Maybe 30-40% chance of Irma entering the Gulf.

Your observations are interesting. Following the board, so many are swept up in hourly runs. East coast talk running high right now. Almost no one looking at the GOM anymore. So when you say 30-40% chance of GOM, I take notice. Still too far out to know the configurations of the trough-ridge set up.

[TheStormExpert]

Obviously still a far far away but when can we expect to start seeing recon missions?

Probably no recon (manned) until next Tuesday at the earliest, once it's west of 50W. I would think that the Global Hawk would be flying missions before then.

I've noticed that the Euro has tended to be too far left/south this season (Cindy/Harvey as examples), while the GFS/CMC have tended to recurve too early. Actual track has tended to be in between the two, generally closer to the Euro than the GFS/CMC. Interesting that the overnight Euro recurves east of the U.S. Way too early to be confident in that. I think a SE U.S. hit is quite possible. Maybe 30-40% chance of Irma entering the Gulf.

What about S.FL?

[otowntiger]

Obviously still a far far away but when can we expect to start seeing recon missions?

Probably no recon (manned) until next Tuesday at the earliest, once it's west of 50W. I would think that the Global Hawk would be flying missions before then.

I've noticed that the Euro has tended to be too far left/south this season (Cindy/Harvey as examples), while the GFS/CMC have tended to recurve too early. Actual track has tended to be in between the two, generally closer to the Euro than the GFS/CMC. Interesting that the overnight Euro recurves east of the U.S. Way too early to be confident in that. I think a SE U.S. hit is quite possible. Maybe 30-40% chance of Irma entering the Gulf.

thanks as always for your insight wxman57. Tho it's hard not to get caught up in the run to run model swings. It's a good reminder to stay vigilant and with it being so far out there also no need for any body to panic. I do however believe there is plenty of reason for optimism that statistically, climatologically historically these storms are generally swept out to sea. Obviously it doesn't always happen, therefore the need to be aware..

[northjaxpro]

Obviously still a far far away but when can we expect to start seeing recon missions?

Probably no recon (manned) until next Tuesday at the earliest, once it's west of 50W. I would think that the Global Hawk would be flying missions before then.

I've noticed that the Euro has tended to be too far left/south this season (Cindy/Harvey as examples), while the GFS/CMC have tended to recurve too early. Actual track has tended to be in between the two, generally closer to the Euro than the GFS/CMC. Interesting that the overnight Euro recurves east of the U.S. Way too early to be confident in that. I think a SE U.S. hit is quite possible. Maybe 30-40% chance of Irma entering the Gulf.

Your observations are interesting. Following the board, so many are swept up in hourly runs. East coast talk running high right now. Almost no one looking at the GOM anymore. So when you say 30-40% chance of GOM, I take notice. Still too far out to know the configurations of the trough-ridge set up.

Read my post in the Irma Models Thread regarding my analysis of Irma potentially "pumping the ridge". It is because of this factor which unfortunately may help bring a major possibility of impacting Irma and having bring the cyclone possibly toward the Gulf Coast region staring down the proverbial gun.

[K4Gators]

Obviously still a far far away but when can we expect to start seeing recon missions?

Probably no recon (manned) until next Tuesday at the earliest, once it's west of 50W. I would think that the Global Hawk would be flying missions before then.

I've noticed that the Euro has tended to be too far left/south this season (Cindy/Harvey as examples), while the GFS/CMC have tended to recurve too early. Actual track has tended to be in between the two, generally closer to the Euro than the GFS/CMC. Interesting that the overnight Euro recurves east of the U.S. Way too early to be confident in that. I think a SE U.S. hit is quite possible. Maybe 30-40% chance of Irma entering the Gulf.

I'm in central Florida, and I tend to wait until things are pretty sure to head to the store, but for this one I think I'll go get water and supplies this weekend!

[Nimbus]

Irma is rolling west precisely following the NHC forecast points.
Currently it appears the official NHC track is going to keep the core winds north of the islands.
There is an ULL in front of Irma pacing west at the same speed which is currently enhancing outflow.
I have pretty good confidence in the official forecast before it becomes a shotgun wedding.
As far as Florida and the gulf I agree with WXman57, there is likely a lack of skill at that range to detect much of a probability anomaly.

[tolakram]

SLIDER

http://rammb-slider.cira.colostate.edu/?sat=goes-16&sec=full_disk&x=19415.5&y=7084.5&z=5&im=12&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&p%5B0%5D=1&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&s=rammb-slider

[WeatherGuesser]

Tho it's hard not to get caught up in the run to run model swings.

No, it's really easy. Just don't pay much attention to them. I never even look at them or the Model threads in general. I wait for NHC to make their forecasts and go with those.

[WeatherGuesser]

I think I'll go get water and supplies this weekend!

Again I have to ask, why 'go and get water'? Why not have empty milk, juice or other jugs on hand and fill them from the tap a day or two ahead? And why not have other supplies like batteries and canned or dry goods on hand always? Fuel for generators and lamps should be on hand too, though it would have to be used since it can go bad.

[GCANE]

I am seeing moderate rain rate on three satellites this morning.
Looks like Irma is on cruise control.
Given the mid-level dry air and low lapse-rate core structure, looks like intensity will be steady for a while.
However, Irma is rolling in a massive amount of low-level moisture (fuel) as depicted on MIMIC-TPW.
She'll crank up down the road, especially given the near ideal upper-level forecast.


http://tropic.ssec.wisc.edu/real-time/m ... anim=html5