ATL: IRMA - Post-Tropical - Discussion

[brghteys1216]

Question for the pros just out of curiosity. How accurate are NWS hourly wind forecasts? Are they usually conservative? Please note I am not manking any decisions based off of this and I am in a safe place. Just genuinely curious.

http://forecast.weather.gov/MapClick.ph ... =graphical

[jasons2k]

The anemometer at Marathon is out...

[Sciencerocks]

000
URNT15 KNHC 100357
AF302 2911A IRMA HDOB 25 20170910
034730 2428N 08006W 6977 03022 //// +077 //// 138070 073 057 005 01
034800 2427N 08008W 6970 03027 9916 +084 //// 140073 075 056 004 01
034830 2426N 08009W 6965 03031 9918 +085 +080 142074 074 056 004 00
034900 2424N 08010W 6966 03026 9911 +087 //// 139076 078 059 004 01
034930 2423N 08011W 6973 03014 9913 +083 //// 141078 078 060 007 01
035000 2422N 08013W 6966 03019 9913 +079 //// 141078 078 060 008 01
035030 2421N 08014W 6968 03012 9909 +077 //// 140078 079 062 012 05
035100 2420N 08015W 6969 03007 //// +076 //// 141078 080 056 013 05
035130 2419N 08016W 6965 03007 //// +082 //// 139081 083 058 010 01
035200 2418N 08018W 6965 03003 9882 +086 //// 136081 083 061 007 01
035230 2416N 08019W 6965 03001 9874 +092 //// 138079 080 061 006 01
035300 2415N 08020W 6969 02992 9873 +091 //// 137080 084 062 006 01
035330 2414N 08021W 6965 02992 //// +085 //// 145080 082 062 009 01
035400 2413N 08023W 6964 02987 //// +089 //// 147080 081 061 013 01
035430 2412N 08024W 6968 02980 //// +087 //// 146079 081 065 014 05
035500 2411N 08025W 6965 02981 //// +085 //// 149075 078 /// /// 05
035530 2410N 08026W 6968 02975 //// +085 //// 150074 076 065 013 05
035600 2409N 08027W 6962 02977 //// +093 //// 147069 072 064 010 01
035630 2408N 08029W 6967 02968 //// +092 //// 148067 069 062 007 01
035700 2406N 08030W 6967 02963 //// +092 //// 146068 070 064 007 01
$$

[cheezyWXguy]

The double wind maxima outside the core is likely putting a ceiling on the amount it can intensify, but it doesn't appear to be altogether preventing it. Just saw radar velocities in the NE quad at 158.8 mph. If such winds can be verified by Recon, that would be more than enough to upgrade this to a cat4. Even if they aren't verified, the general trend that radar presents is that the core is definitely still getting better organized and the windfield is intensifying. Radar velocities were only about 115mph about 5 hours ago, and about 130mph about 2 hours ago.

[romeoblade]

Harvey, and now Irma have all but proved to me that the Saffir Simpson Hurricane Scale is a broken way of categorizing storms. Categorizing an event on wind speed alone is patently dangerous, and creates a skewed perception of reality by the layperson. Irma might not be a category 4 or 5 storm any longer, but it certainly has an expansive hurricane force wind field that is atypical of you average land-falling cat 2/3 and a storm surge threat that might be catastrophic under the right conditions. It is time to do away with this scale as the sole way of categorizing an operational tropical cyclone, and institute a new system that will better relay the specific threats of a storm to the public.

Well said, and I agree!

[SuperMarioBros99thx]

What's making the GFS predict a NE shift after making landfall somehwere near Fort Meyers??? ...

Well... that through to the north of Irma.

[bamajammer4eva]

Why does the eyewall look more like a football than being round?

[Sciencerocks]

000
URNT15 KNHC 100407
AF302 2911A IRMA HDOB 26 20170910
035730 2405N 08031W 6968 02957 //// +094 //// 144064 067 065 007 01
035800 2404N 08032W 6970 02952 //// +096 //// 143065 066 066 008 01
035830 2403N 08034W 6967 02948 9795 +113 +107 144068 069 066 006 00
035900 2402N 08035W 6969 02942 9793 +110 //// 145072 073 065 004 01
035930 2401N 08036W 6967 02941 9794 +097 //// 144076 078 066 006 01
040000 2400N 08037W 6971 02926 9785 +100 //// 143076 079 067 010 01
040030 2359N 08039W 6967 02925 9780 +105 //// 141077 078 067 009 01
040100 2357N 08040W 6966 02923 9776 +104 +100 140079 080 066 005 00
040130 2356N 08041W 6969 02913 9771 +102 +098 139082 082 067 007 00
040200 2355N 08042W 6966 02907 9762 +100 //// 138082 083 068 007 01
040230 2354N 08044W 6971 02893 9755 +097 //// 138084 085 067 006 01
040300 2353N 08045W 6962 02895 //// +088 //// 140088 090 069 011 01
040330 2352N 08046W 6964 02880 //// +093 //// 139089 090 070 008 01
040400 2351N 08047W 6968 02861 //// +088 //// 138091 092 071 012 05
040430 2349N 08049W 6956 02863 //// +085 //// 138095 096 075 018 01
040500 2348N 08050W 6967 02834 //// +082 //// 137100 102 078 024 01
040530 2347N 08051W 6970 02813 //// +073 //// 136104 106 078 024 01
040600 2346N 08052W 6939 02830 //// +082 //// 145104 107 088 038 01
040630 2345N 08053W 6978 02756 //// +083 //// 144106 108 093 042 01
040700 2344N 08054W 6968 02740 //// +087 //// 146106 110 097 043 01
$$

[SuperMarioBros99thx]

Why does the eyewall look more like a football than being round?

I don't know. Probably some interaction of Cuba might be cause of this.

[Macrocane]

RECON has not found stronger winds yet but we can't deny the increase in organization:
-Eye has cleared out
-Cloud tops have cooled down
-Core is getting more symmetric.

A better organizations means faster restreghtening.
Anyway, we shouldn't be obsessed with wind speed. Storm surge can be pretty bad in "weaker hurricanes" as Ike, Sandy and Matthew taught us.

[Blinhart]

The double wind maxima outside the core is likely putting a ceiling on the amount it can intensify, but it doesn't appear to be altogether preventing it. Just saw radar velocities in the NE quad at 158.8 mph. If such winds can be verified by Recon, that would be more than enough to upgrade this to a cat4. Even if they aren't verified, the general trend that radar presents is that the core is definitely still getting better organized and the windfield is intensifying. Radar velocities were only about 115mph about 5 hours ago, and about 130mph about 2 hours ago.

So another words we are just waiting on these winds to work their way down to the surface. If they work all the way down to the surface at 160 MPH it would be a Cat 5.

I'm looking at the radar that there is a possible second eyewall that is about 75 to 100 miles from the center basically cutting the storm into two separate entities. So is it possible we could see the inner eye stay with the storms in between the inner and outer eye stay there and increase their speeds. I think it is trying to do something not seen often or ever.

[CaptinCrunch]

From our local professional met.

Irma has made the move to due NW as of 10 PM CDT and will eventually turn even more to the north and will pass close to Key West in the morning on her way to Naples/Fort Myers/Tampa during the afternoon and evening Sunday.

The good news is she continues to weaken slightly, down to 120 mph. The bad news is, once she gets to the other side of the Keys, the waters are significantly warmer and could allow Irma to regain Cat 4 strength briefly before moving into SW Florida.

[Blinhart]

Why does the eyewall look more like a football than being round?

I don't know. Probably some interaction of Cuba might be cause of this.

Eye walls are typically not a concentric circle, there are meso-vortices inside the eye that cause it to look oblong.

[jasons2k]

You can see the outflow is expanding in all quadrants. It will be awhile before shear disrupts Irma.

[Blown Away]

Finally seeing close to due N tug..

[Sciencerocks]

000
URNT15 KNHC 100417
AF302 2911A IRMA HDOB 27 20170910
040730 2343N 08055W 6965 02724 //// +100 //// 153099 110 106 029 01
040800 2342N 08057W 6970 02685 //// +113 //// 152091 094 108 024 01
040830 2341N 08058W 6963 02673 //// +129 //// 151092 093 113 012 05
040900 2340N 08059W 6973 02632 9448 +121 //// 153087 090 109 012 01
040930 2340N 08101W 6963 02614 9409 +128 //// 157081 084 089 013 05
041000 2339N 08102W 6963 02588 9359 +150 //// 154066 079 071 005 01
041030 2338N 08104W 6970 02558 9322 +167 +158 151044 060 063 003 00
041100 2337N 08105W 6967 02555 9311 +170 +155 151030 038 039 001 00
041130 2336N 08107W 6968 02547 9311 +162 +159 143015 025 019 002 00
041200 2335N 08108W 6966 02545 9313 +156 //// 078002 011 017 000 05
041230 2334N 08110W 6965 02550 9317 +155 //// 331012 016 017 000 01
041300 2332N 08111W 6970 02550 9327 +153 //// 325025 031 016 001 05
041330 2333N 08113W 6963 02570 9331 +159 +145 333039 042 039 001 00
041400 2334N 08114W 6965 02570 9322 +173 +147 344048 052 042 002 00
041430 2334N 08115W 6969 02572 9331 +174 +144 354060 063 051 001 03
041500 2335N 08117W 6967 02590 9353 +169 +141 002071 077 064 004 00
041530 2336N 08118W 6962 02621 9377 +172 +121 005077 080 081 002 03
041600 2337N 08119W 6957 02637 9394 +163 +123 008077 081 085 002 00
041630 2338N 08119W 6967 02627 9405 +156 +129 014084 085 090 001 00
041700 2339N 08120W 6970 02640 9423 +152 +130 018088 089 097 002 00
$$

[bjackrian]

Pressure at 931 extrap, but recon pass appears to support 110 kt surface winds in NE quad.

040730 2343N 08055W 6965 02724 //// +100 //// 153099 110 106 029 01
040800 2342N 08057W 6970 02685 //// +113 //// 152091 094 108 024 01
040830 2341N 08058W 6963 02673 //// +129 //// 151092 093 113 012 05
040900 2340N 08059W 6973 02632 9448 +121 //// 153087 090 109 012 01
040930 2340N 08101W 6963 02614 9409 +128 //// 157081 084 089 013 05
041000 2339N 08102W 6963 02588 9359 +150 //// 154066 079 071 005 01
041030 2338N 08104W 6970 02558 9322 +167 +158 151044 060 063 003 00
041100 2337N 08105W 6967 02555 9311 +170 +155 151030 038 039 001 00
041130 2336N 08107W 6968 02547 9311 +162 +159 143015 025 019 002 00
041200 2335N 08108W 6966 02545 9313 +156 //// 078002 011 017 000 05
041230 2334N 08110W 6965 02550 9317 +155 //// 331012 016 017 000 01
041300 2332N 08111W 6970 02550 9327 +153 //// 325025 031 016 001 05

[meriland29]

She is really looking her part on the floater radar, look at how the eye has reformed in the past few hours...I am not a pro-met or anything, but that looks quite...

[Alyono]

I'll be shocked if NHC goes 110 kts, since they didn't really believe the 105 kts last time (they threw out the 101 kt sfmr). The data was flagged, so it may not be given as much value

[FLpanhandle91]

Pressure at 931 extrap, but recon pass appears to support 110 kt surface winds in NE quad.

040730 2343N 08055W 6965 02724 //// +100 //// 153099 110 106 029 01
040800 2342N 08057W 6970 02685 //// +113 //// 152091 094 108 024 01
040830 2341N 08058W 6963 02673 //// +129 //// 151092 093 113 012 05
040900 2340N 08059W 6973 02632 9448 +121 //// 153087 090 109 012 01
040930 2340N 08101W 6963 02614 9409 +128 //// 157081 084 089 013 05
041000 2339N 08102W 6963 02588 9359 +150 //// 154066 079 071 005 01
041030 2338N 08104W 6970 02558 9322 +167 +158 151044 060 063 003 00
041100 2337N 08105W 6967 02555 9311 +170 +155 151030 038 039 001 00
041130 2336N 08107W 6968 02547 9311 +162 +159 143015 025 019 002 00
041200 2335N 08108W 6966 02545 9313 +156 //// 078002 011 017 000 05
041230 2334N 08110W 6965 02550 9317 +155 //// 331012 016 017 000 01
041300 2332N 08111W 6970 02550 9327 +153 //// 325025 031 016 001 05

Still a potent storm. Supports 125 mph with pressure still dropping. Still plenty of time to strengthen. Do NOT write off this storm folks.