ATL: IRMA - Post-Tropical - Discussion

[PandaCitrus]

Can someone explain the NHC 11PM advisory weakens Irma to 140MPH in the Florida Keys. Is there going to be shear? Are they forecasting Cuba to disrupt the core? Are they afraid to predict a Cat 5 on landfall in Florida?

It just doesn't make sense considering the oceanic heat content around South Florida is the highest in the entire Atlantic Basin. If Irma did 185MPH where he is now, there's no reason he can't do 200 in the Gulf Stream waters that are warmer.

If Irma doesn't hit Cuba, are they just praying for an eyewall replacement cycle? What's preventing a Cat 5 Florida landfall?

[smithtim]

real intense hurricane double eyewalls occasionally do what just happened.. not often though..

Does it mean reached peak and will sustain current structure until something in environment ( e.g. land interactions, change in sea temperature/ depth ) causes it to decrease??

Or did those prior storms mentioned continue to deepen?

[eastcoastFL]

Did the wind field shrink? Ts is the same but the hurricane force winds was 60 miles out and now it's 50?

[Aric Dunn]

real intense hurricane double eyewalls occasionally do what just happened.. not often though..

Does it mean reached peak and will sustain current structure until something in environment ( e.g. land interactions, change in sea temperature/ depth ) causes it to decrease??

Or did those prior storms mentioned continue to deepen?

Good Question. its something that is not well understood..

[nascarfan999]

Automated C-Man station in Barbuda.

http://www.ndbc.noaa.gov/station_page.php?station=bara9

One tip, if you click on the "Water Level" link right above the measurements it will take you to a page with graphs, the pressure readout in mb, and, as the name suggests, water levels at the gauge to measure surge. I don't know the science of it, but interesting to see the water temperature already down 3* and falling.

[RL3AO]

Can someone explain the NHC 11PM advisory weakens Irma to 140MPH in the Florida Keys. Is there going to be shear? Are they forecasting Cuba to disrupt the core? Are they afraid to predict a Cat 5 on landfall in Florida?

Too many uncertainties. If it stays north of Cuba it'll be stronger. If it goes over Cuba it will be weaker. They have to make ONE forecast which means a hedge down the middle.

[drewschmaltz]

real intense hurricane double eyewalls occasionally do what just happened.. not often though..

Does it mean reached peak and will sustain current structure until something in environment ( e.g. land interactions, change in sea temperature/ depth ) causes it to decrease??

Or did those prior storms mentioned continue to deepen?

Ok, so here's a question ... (of the many I've lost below the fold in the past half hour)... what's the maximum wind speed that has seen a successful ERC? Maybe double wind maxima occurs at this intensity, but replacement does not occur, just merging...

[CrazyC83]

000
URNT15 KNHC 060257
AF305 1111A IRMA HDOB 33 20170906
024830 1819N 06158W 6966 03133 0005 +107 +072 070066 066 046 004 00
024900 1818N 06157W 6971 03126 9987 +121 +072 069067 067 047 004 00
024930 1817N 06156W 6964 03131 9992 +117 +071 067066 066 048 005 00
025000 1816N 06155W 6970 03123 9991 +119 +071 065065 065 048 005 00
025030 1815N 06154W 6966 03129 9994 +115 +071 062064 065 049 005 00
025100 1814N 06152W 6967 03126 9994 +110 +071 059063 064 051 006 00
025130 1812N 06151W 6966 03124 9996 +108 +071 057063 063 052 005 00
025200 1811N 06150W 6970 03119 0003 +102 +070 057066 069 053 005 00
025230 1810N 06149W 6967 03117 0000 +103 +070 059072 072 052 006 00
025300 1809N 06148W 6969 03113 9991 +109 +068 059072 073 054 005 00
025330 1808N 06146W 6966 03114 9984 +110 +067 056071 072 054 005 00
025400 1807N 06145W 6967 03109 9995 +099 +067 055072 073 055 006 00
025430 1806N 06144W 6967 03105 9998 +093 +066 054071 073 054 006 00
025500 1805N 06143W 6969 03098 9991 +095 +065 053075 076 055 005 00
025530 1803N 06142W 6967 03097 9992 +088 +064 057077 079 056 006 00
025600 1802N 06141W 6967 03089 9989 +086 +062 058080 083 058 006 00
025630 1801N 06140W 6967 03083 9975 +092 +060 060079 080 058 005 00
025700 1800N 06138W 6967 03075 9976 +084 +058 059081 082 059 005 00
025730 1759N 06137W 6961 03075 9969 +083 +057 059086 087 062 005 00
025800 1758N 06136W 6967 03060 9945 +097 +056 062086 087 063 003 00
$$
;

[Aric Dunn]

Can someone explain the NHC 11PM advisory weakens Irma to 140MPH in the Florida Keys. Is there going to be shear? Are they forecasting Cuba to disrupt the core? Are they afraid to predict a Cat 5 on landfall in Florida?

It just doesn't make sense considering the oceanic heat content around South Florida is the highest in the entire Atlantic Basin. If Irma did 185MPH where he is now, there's no reason he can't do 200 in the Gulf Stream waters that are warmer.

If Irma doesn't hit Cuba, are they just praying for an eyewall replacement cycle? What's preventing a Cat 5 Florida landfall?

at some point you have to look back at previous hurricanes... they rarely stay cat 5 or even 4 for very long without ERC or other issues. its better to forecast some slight weakening than to lie and say it will be 185 mph for 5 days..
the potential is there for a cat 5 but there are a lot of variables ...

[CryHavoc]

Can someone explain the NHC 11PM advisory weakens Irma to 140MPH in the Florida Keys. Is there going to be shear? Are they forecasting Cuba to disrupt the core? Are they afraid to predict a Cat 5 on landfall in Florida?

It just doesn't make sense considering the oceanic heat content around South Florida is the highest in the entire Atlantic Basin. If Irma did 185MPH where he is now, there's no reason he can't do 200 in the Gulf Stream waters that are warmer.

If Irma doesn't hit Cuba, are they just praying for an eyewall replacement cycle? What's preventing a Cat 5 Florida landfall?

Our intensity forecasts are usually extremely conservative.

[Snowman67]

Weather starting to go downhill in Aruba and Barbuda.

Edit: Antigua and Barbuda.

Yup. Winds up to 55mph and pressure down to 29.28

https://www.accuweather.com/en/ag/codri ... ather/2302

[Raebie]

Cone shifts north and east some.

That doesn't look like a shift. It looks like a progression.

[Sanibel]

Creepy dead calm again here tonight with the crickets like last night...You can see the gradient delineation in the direction of Irma in the thin cirrus in the full moon...


Getting mother out tomorrow and up to Charleston...Too risky to chance...

[Aric Dunn]

geeezz. last frame of the radar.. ! feel really bad for whoever is on that tiny island.. and the next one and the other after.. and PR since unles it wobbles NE PR is likely going to have the strongest winds the islands has ever experienced and likely in san juan..
http://barbadosweather.org/Composite/ki ... site=Sabre

[meriland29]

I see there is a live webcam for St. Barts as well as the BVI, but is there one for Barbuda?

[SoupBone]

Creepy dead calm again here tonight with the crickets like last night...You can see the gradient delineation in the direction of Irma in the thin cirrus in the full moon...


Getting mother out tomorrow and up to Charleston...Too risky to chance...

Happened before Harvey too. Posters prepping hopefully.

[Ken711]

Cone shifts north and east some.

That doesn't look like a shift. It looks like a progression.

Yes like a progressive shift north.

[Evenstar]

Someone very close to me was named "Irma". Not a very common name at all, anymore. Have to ask the priestess, but seems like a lot of power in that name.

Alarmingly, my Dad wanted to name me Irma (grandmother's middle name), but my Mom put the kibosh on that (thank gawd). I've hated that name ever since I heard that story. My inner voodoo priestess tells me this is not a good sign.

I remembered how eerily correct everyone's feelings were early on, how uncanny.

Irma's got some powerful voodoo, to be sure. Maybe that's why she was so worrisome from the moment she left the coast of Africa. Very powerful voodoo indeed.
(I just hope she doesn't take my hatred of the name Irma personally...)

[Aric Dunn]

pretty much two eyewalls merged to become one really thick crazy.... EYEWALL>> !!

[Noles2016]

A shift of 20 miles or so in the 5 day range is rather insignificant given the margin of error...