ATL: IRMA - Post-Tropical - Discussion

[CrazyC83]

000
URNT15 KNHC 051658
AF309 0811A IRMA HDOB 48 20170905
164930 1712N 05917W 6969 02923 9783 +103 //// 065117 120 088 006 01
165000 1713N 05918W 6969 02942 9798 +108 +101 064112 117 084 001 00
165030 1715N 05920W 6965 02976 9816 +098 //// 060106 107 083 002 01
165100 1716N 05921W 6969 02977 9867 +089 //// 059110 115 077 003 01
165130 1717N 05922W 6972 02990 9888 +091 +091 055103 111 074 006 00
165200 1719N 05923W 6976 02996 9921 +071 //// 051091 097 073 008 01
165230 1720N 05924W 6963 03025 9907 +082 //// 056091 092 070 003 01
165300 1721N 05925W 6974 03021 9922 +086 +083 056087 090 069 002 03
165330 1722N 05927W 6970 03033 9954 +080 +080 050090 092 064 010 00
165400 1724N 05928W 6954 03059 9957 +079 //// 049084 090 064 009 01
165430 1725N 05929W 6973 03048 9954 +083 //// 048076 081 062 004 01
165500 1726N 05930W 6970 03055 9954 +085 +084 050079 080 062 005 01
165530 1727N 05931W 6969 03065 9972 +080 //// 048083 084 061 004 01
165600 1728N 05932W 6961 03078 9973 +079 +077 046080 083 058 004 00
165630 1730N 05933W 6970 03071 9977 +082 +077 049080 081 058 004 00
165700 1731N 05935W 6968 03077 9965 +092 +078 048076 079 056 004 00
165730 1732N 05936W 6968 03076 9961 +096 +078 049074 075 053 002 00
165800 1733N 05937W 6970 03078 9961 +100 +076 052073 074 053 003 00
165830 1735N 05938W 6969 03086 9964 +103 +070 057074 074 049 004 00
165900 1736N 05939W 6970 03083 9964 +103 +068 061074 075 048 005 00
$$
;

[Michele B]

Okay...so it seems a lot of people are fearing they will have to evacuate to a further distance than usual because they are concerned of a Harvey-type inland flooding scenario. I'm not sure how worried you should really be like this and here's why:

1. Harvey parked over Texas for 5 days. Unless Irma's going to be hovering over one location for that long I doubt the rainfall totals will be comparable.
2. As someone who has been through a ton of freshwater flooding, and someone who went to Galveston right after Ike, there really is no comparison between freshwater flooding and storm surge. Unless you live right next to a river or on a mountainside, inland flooding moves a lot more slowly and with less power behind it. As long as you don't venture outside into the floodwaters with a car or on foot you generally can stay safe on upper floor levels. So if you have to choose between surge and inland flooding, choose inland flooding. You might not be able to evacuate away from the path of all impacts.
3. Houston just is uniquely vulnerable to flooding. My neighborhood there floods several times a year due to its unfortunate combination of impermeable soil, countless bayous, and pavement. If you avoid regions like that it won't be as bad.

As far as the fight over whether we can call Irma beautiful or not...
"She's beauty, she's grace; she'll throw a tree in your face."
...as in,
Sometimes you need to use a bit of humor to regain your composure so you can finish preparing.

Thanks for the smile for us all!

It isn't just flooding they're evacuating in this case. It's the fact that without a strong enough structure to hunker down in, this monster could just blow away everything around you.

I'm telling you, I've ALWAYS made sure I've lived in a very strong home, with window coverings and all that, but I'm freaking out a little bit on this one, just because of the sheer STRENGTH of the winds in it.

This is like an F1 tornado coming through. A tornado usually tears through a neighborhood, a house in seconds. This thing could be several HOURS going over. And that's assuming she keep moving at the clip she's going. I don't see anything that indicates she'll slow down or stall like Harvey (that is a blessing) Once that trough picks her up, it'll sling her northward quite quickly, I suspect....I hope...

[Michele B]

"...fluctuations in intensity are likely to occur as eyewall replacement cycles take place...." (The NHC, as its forecast slowly bleeds off strength from Irma 180>175>etc. prior to passage north of Puerto Rico)

-- This makes absolutely no sense to me. They're not predicting an increase in shear or other mitigating factor, and the Virgin Islands present no disruptive profile to the wind. So, why expect weakening?

Irma is now a steady-state, top-ended hurricane with an almost annular-looking core. Allen, David, Mitch, and Isabel showed that such storms can and do supercruise at cat-5 until they approach land (or, in the case of Isabel, plow through howling shear).

Hurricanes rarely maintain a maxed out intensity for long...at this point it's reasonable to expect some fluctuations in intensity. it will be interesting to see if downsloping off the greater Antilles has an adverse impact on the system when it reaches that longitude.

But we're not talking about hurricanes in general; we're talking about specific hurricanes in this particular situation: top-ended ones (not pinholes). Go look at Allen's track: if it weren't for all the Greater Antilles is brushed up against threading the needle, that storm would have been a cat-5 for four solid days.

If the ocean heat content under Iram presently supports a top-ended intensity of 180mph, then the higher heat content west of the storm does not suggest weakening is in the future. If the storm hits a big, mountainous island, it will weaken. If it runs into shear, it will weaken. But on the forecast track they're projecting, there is no logical reason for it to weaken in the next 24hours.

I hear you, Shuriken, but I've never seen a storm maintain that level of intensity for very long, in 60 years of "watching" them.

I don't know if it's - as you say - interaction with a land mass, or something to do with the amount of energy that is expended while being that strong....idk.

I'm just glad to think it WILL weaken. I HOPE it weakens!

[msbee]

Please pray for St Maarten and the northern Caribbean islands

[La Sirena]

Please pray for St Maarten and the northern Caribbean islands

Y'all are definitely in my thoughts and prayers.

[ronyan]

The eye wall currently has winds similar to a moderate EF-4 tornado. 185 mph is ridiculous.

[GCANE]

[SunnyThoughts]

How intense do you guys think this could become before it just isn't scientifically possible for it to get any stronger? I mean there has to be a threshold right. Have there been any thesis or papers written considering how physically possible it is for a cyclone to become?

[txwatcher91]

Here’s a question I haven’t seen answered yet. The FL winds seem a little lower than the surface winds detected by SFMR. I know years ago when it was first introduced they would base it off FL winds and if the SFMR showed higher surface winds they’d discount it. I assume this instrument has been tweaked and is more accurate now??

[Evenstar]

The eye wall currently has winds similar to a moderate EF-4 tornado. 185 mph is ridiculous.

This is exactly what I was thinking. It's like a HUGE tornado. Terrifying.

[storm_in_a_teacup]

Okay...so it seems a lot of people are fearing they will have to evacuate to a further distance than usual because they are concerned of a Harvey-type inland flooding scenario. I'm not sure how worried you should really be like this and here's why:

1. Harvey parked over Texas for 5 days. Unless Irma's going to be hovering over one location for that long I doubt the rainfall totals will be comparable.
2. As someone who has been through a ton of freshwater flooding, and someone who went to Galveston right after Ike, there really is no comparison between freshwater flooding and storm surge. Unless you live right next to a river or on a mountainside, inland flooding moves a lot more slowly and with less power behind it. As long as you don't venture outside into the floodwaters with a car or on foot you generally can stay safe on upper floor levels. So if you have to choose between surge and inland flooding, choose inland flooding. You might not be able to evacuate away from the path of all impacts.
3. Houston just is uniquely vulnerable to flooding. My neighborhood there floods several times a year due to its unfortunate combination of impermeable soil, countless bayous, and pavement. If you avoid regions like that it won't be as bad.

As far as the fight over whether we can call Irma beautiful or not...
"She's beauty, she's grace; she'll throw a tree in your face."
...as in,
Sometimes you need to use a bit of humor to regain your composure so you can finish preparing.

Thanks for the smile for us all!

It isn't just flooding they're evacuating in this case. It's the fact that without a strong enough structure to hunker down in, this monster could just blow away everything around you.

I'm telling you, I've ALWAYS made sure I've lived in a very strong home, with window coverings and all that, but I'm freaking out a little bit on this one, just because of the sheer STRENGTH of the winds in it.

This is like an F1 tornado coming through. A tornado usually tears through a neighborhood, a house in seconds. This thing could be several HOURS going over. And that's assuming she keep moving at the clip she's going. I don't see anything that indicates she'll slow down or stall like Harvey (that is a blessing) Once that trough picks her up, it'll sling her northward quite quickly, I suspect....I hope...

I'm going to confess I don't know much about preparing for wind. All the storms I have been through have been mostly water, whether it be from rain or surge. It's kind of strange if I think about it, because everyone associates the word hurricane with "wind," but my first association is with "water."

[Alyono]

The eye wall currently has winds similar to a moderate EF-4 tornado. 185 mph is ridiculous.

I believe tornadoes are rated based upon the gusts (please correct me if wrong). Thus, the winds are EF5 strength now

[dukeblue219]

How intense do you guys think this could become before it just isn't scientifically possible for it to get any stronger? I mean there has to be a threshold right. Have there been any thesis or papers written considering how physically possible it is for a cyclone to become?

There is such a thing as maximum potential intensity: http://wxmaps.org/pix/hurpot.html and https://en.wikipedia.org/wiki/Tropical_ ... _intensity

Basically, friction with the ocean increases as the cube of windspeed. Evaporation only increases linearly. Eventually there's a point where these forces (and a lot of other stuff) line up and it can't go faster, kind of like the terminal velocity of a rock dropped from a plane.

[jlauderdal]

for sofla and even people that care to watch online...fyi, max mayfield former nhc director is employed by channel 10 so after you catch general hospital tune into pics from gas stations, publix and home depot

Local 10 Special #HurricaneIrma coverage starts at 3pm today @WPLGLocal10, immediately following @GeneralHospital

[CrazyC83]

000
URNT15 KNHC 051708
AF309 0811A IRMA HDOB 49 20170905
165930 1737N 05941W 6969 03086 9973 +096 +068 066074 075 048 006 00
170000 1739N 05942W 6970 03081 9970 +100 +065 067073 074 049 003 00
170030 1740N 05943W 6970 03086 9959 +112 +066 064071 073 048 004 00
170100 1741N 05945W 6968 03098 9966 +113 +064 061070 072 047 001 00
170130 1743N 05946W 6974 03091 9964 +116 +061 062069 072 046 000 03
170200 1744N 05947W 6963 03105 9957 +122 +055 062066 067 047 000 03
170230 1746N 05949W 6970 03103 9969 +118 +054 063065 066 047 000 03
170300 1746N 05950W 6978 03094 9975 +117 +050 064063 064 045 001 00
170330 1747N 05953W 6911 03166 9968 +108 +044 060065 066 045 001 03
170400 1747N 05955W 6690 03433 9967 +090 +029 060070 071 /// /// 03
170430 1748N 05957W 6486 03694 9958 +082 +014 060067 071 /// /// 03
170500 1748N 05959W 6259 03986 9967 +058 +008 058062 066 /// /// 03
170530 1748N 06001W 6020 04303 9962 +040 -004 056058 059 /// /// 03
170600 1749N 06003W 5815 04591 9968 +026 -018 054056 057 040 000 03
170630 1749N 06005W 5728 04732 9984 +018 -025 053055 057 040 000 00
170700 1750N 06008W 5717 04753 9997 +014 -025 054056 057 038 000 00
170730 1750N 06010W 5720 04748 9998 +014 -026 055057 058 035 000 03
170800 1751N 06013W 5721 04749 9994 +017 -031 052056 058 036 000 00
170830 1751N 06015W 5718 04753 0002 +012 -026 054057 058 036 000 03
170900 1752N 06017W 5726 04745 0014 +009 -016 051055 058 036 000 00
$$
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[znel52]

How intense do you guys think this could become before it just isn't scientifically possible for it to get any stronger? I mean there has to be a threshold right. Have there been any thesis or papers written considering how physically possible it is for a cyclone to become?

Well Patricia in the EPAC hit sustained winds of 215mph and a pressure of 872mb so even though this was probably an anomaly we may never see again it technically still has room to grow.

[NDG]

Every time I say she has the best satellite presentation it proves me wrong, she just keeps getting better on satellite.

[Hurricaneman]

Honestly a sub 900mb hurricane is actually quite possible in the Florida straits but my guess is it's going to peak between 900 and 910

[Extratropical94]

How intense do you guys think this could become before it just isn't scientifically possible for it to get any stronger? I mean there has to be a threshold right. Have there been any thesis or papers written considering how physically possible it is for a cyclone to become?

There is such a thing as maximum potential intensity: http://wxmaps.org/pix/hurpot.html

Quite scary that according to these maps the MPI is between 135 and 150 knots at Irma's current location. And she is at 155 and strengthening...

[CrazyC83]

000
URNT12 KNHC 051705
VORTEX DATA MESSAGE AL112017
A. 05/16:38:10Z
B. 16 deg 53 min N
058 deg 53 min W
C. 700 mb 2440 m
D. 160 kt
E. 054 deg 14 nm
F. 138 deg 151 kt
G. 054 deg 15 nm
H. 926 mb
I. 9 C / 3066 m
J. 18 C / 3052 m
K. 13 C / NA
L. CLOSED
M. C24
N. 12345 / 7
O. 0.02 / 1 nm
P. AF309 0811A IRMA OB 21
MAX FL WIND 151 KT 054 / 15 NM 16:33:00Z
MAX OUTBOUND FL WIND 148 KT 299 / 16 NM 16:44:30Z
CNTR DROPSONDE SFC WIND 180 / 4 KT
MAX FL TEMP 19 C 062 / 7 NM FROM FL CNTR
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