ATL: IRMA - Post-Tropical - Discussion

[FLpanhandle91]

The 00Z run is forecasting Irma to bomb to 916 mb at 12Z this morning as she landfall in Key West.

GFS is saying a pressure drop of about 14 mb from now til landfall in Key West.

Well, it will probably be in the 922 -925 range I think on her approach in 5 hours from now.

But. I it is plausible to happe

That possibility will come to fruition within the next couple hours IMO. Irma's inner eye-wall is completely gone. If she can close off her outer eye-wall completely before she hits the shear her core's vertical presentation diminishes, then I can see even further strengthening than 922-925.

[Aric Dunn]

The 00Z run is forecasting Irma to bomb to 916 mb at 12Z this morning as she landfall in Key West.

GFS is saying a pressure drop of about 14 mb from now til landfall in Key West.

Well, it will probably be in the 922 -925 range I think on her approach in 5 hours from now.

But it is plausible to happen.

not likely with the current set up.. unless something changes its pushing the upper limit of its intensity due to the upper environment.

[bamajammer4eva]

Severe weather (tornado) risk is Enhanced with 10% in Eastern FL

...Florida and adjacent south Atlantic coastal areas...
The northward forecast track of Irma, along (near and just west of)
Gulf coastal areas, could allow for an appreciable risk for
longer-lived supercells across at least the interior peninsula and
Atlantic coastal areas, with northward/northwestward storm motions
tending to be aligned with the major axis of the peninsula. North
through east of the center of Irma, lower/mid tropospheric
hodographs are forecast to be large to extreme in size, with
considerable clockwise curvature, more than supportive of potential
for sustained low-level mesocyclones, and the risk for tornadoes
within the more moist and potentially unstable boundary layer air.
The extent of this potential will considerably hinge on boundary
layer warming between the stronger convective bands pivoting around
the circulation center of Irma. This remains unclear at the present
time, but at least a few tornadoes appear possible, particularly
during the daytime hours within a corridor between the Greater Miami
metro area and Orlando/Melbourne.

Continuing tornado potential late this evening into daybreak Monday
becomes more unclear farther to the north, particularly across and
inland of Georgia/Carolina coastal areas, where near-surface wind
fields may maintain a northerly component, emanating from a
dry/potentially cool environment associated with expansive surface
ridging centered over the lower Great Lakes region.

[Sciencerocks]

000
URNT15 KNHC 100717
AF302 2911A IRMA HDOB 45 20170910
070730 2433N 08207W 6965 02975 9832 +104 //// 075070 072 101 013 05
070800 2432N 08206W 6969 02969 9833 +102 //// 074071 072 065 003 01
070830 2431N 08205W 6969 02964 9816 +111 //// 073063 071 059 010 01
070900 2430N 08204W 6959 02973 9826 +101 //// 073070 074 058 012 05
070930 2429N 08203W 6955 02974 9814 +108 //// 071064 073 058 014 05
071000 2428N 08202W 6950 02974 9805 +111 //// 061054 060 058 012 05
071030 2427N 08200W 6964 02954 9781 +127 +118 049051 053 058 006 00
071100 2426N 08159W 6970 02946 9777 +128 +115 048053 053 058 005 00
071130 2424N 08158W 6971 02941 9767 +133 +116 051054 055 051 003 00
071200 2423N 08157W 6966 02943 9761 +135 +113 049055 056 053 002 00
071230 2422N 08155W 6967 02936 9762 +129 +114 047056 057 057 002 00
071300 2421N 08154W 6970 02928 9742 +143 +108 047056 057 060 001 00
071330 2420N 08153W 6971 02920 9732 +147 +106 047060 062 060 001 00
071400 2418N 08151W 6967 02919 9729 +143 +105 044063 063 059 001 00
071430 2417N 08150W 6970 02909 9722 +144 +097 043061 064 059 002 00
071500 2416N 08149W 6970 02901 9714 +143 +091 041060 060 062 001 00
071530 2415N 08147W 6970 02893 9696 +153 +089 042061 062 063 002 00
071600 2414N 08146W 6962 02893 9685 +155 +092 042062 063 061 003 00
071630 2412N 08145W 6974 02870 9676 +154 +091 043065 065 060 003 00
071700 2411N 08143W 6970 02867 9670 +148 +097 048072 073 062 004 00
$$

[bob rulz]

Since 1851, there has never been a year with two landfalling storms of cat 4+ intensity in the CONUS. We may be hours from history...

What about 1915?

The Galveston hurricane was a category 4, but the New Orleans hurricane was downgraded to a category 3 at landfall in the re-analysis project, as can be seen on page 21 of the re-analysis report here:
http://www.aoml.noaa.gov/hrd/Landsea/reanal_1911-20.pdf

And I recognize this is off-topic so I won't continue this discussion. But it at least does clear up the historical record about category 4 landfalls in the United States. According to official reports, this will be the first time assuming Irma maintains cat 4 intensity (and there's no reason to suspect it won't), but obviously the further back you go, the less reliable the records become.

[brghteys1216]

How accurate are the NWS hourly wind estimates? What do you think we should expect in terms of sustained and gust winds in Orlando?

[hiflyer]

Hurricane force 70 miles either side could surprise a few west coasters inland...15 inches rain on the peninsula going be interesting after that june storm caused major flooding Broward....hopefully SFWMD got the levels down this time. Only one commercial aircraft approaching florida...Taca going to NYC coming up on the coast above Tampa from the gulf...not expecting any airports open for commercial before Monday at the earliest now I hear...

[northjaxpro]

Seems to me Irma is walling off that shear for the moment. She may have about a 6-8 hour window to intensify significantly Aric.

[Sciencerocks]

000
URNT15 KNHC 100727
AF302 2911A IRMA HDOB 46 20170910
071730 2410N 08142W 6963 02861 9665 +140 +098 046075 077 063 005 00
071800 2409N 08141W 6966 02845 9660 +132 +099 046077 078 063 007 00
071830 2408N 08140W 6973 02820 9650 +124 +110 047082 083 065 006 00
071900 2407N 08138W 6972 02806 9626 +131 +110 045087 089 068 008 00
071930 2405N 08137W 6969 02789 9603 +133 +096 043092 095 074 006 00
072000 2404N 08136W 6967 02771 9572 +140 +107 041099 100 077 007 00
072030 2403N 08134W 6972 02739 9547 +138 +098 040102 103 080 018 00
072100 2402N 08133W 6961 02722 9538 +114 //// 037100 103 090 028 01
072130 2401N 08132W 6964 02677 9498 +123 //// 033103 110 102 036 01
072200 2400N 08131W 6981 02609 9400 +135 //// 026087 096 104 016 05
072230 2359N 08129W 6954 02612 9340 +190 +132 028073 084 090 004 00
072300 2358N 08127W 6977 02559 9320 +181 +150 028051 067 069 003 00
072330 2357N 08126W 6969 02552 9300 +182 +153 036038 043 043 001 03
072400 2356N 08124W 6969 02538 9283 +187 +136 048024 034 031 002 00
072430 2355N 08122W 6972 02525 9274 +187 +133 066013 020 021 000 03
072500 2354N 08121W 6969 02525 9274 +181 +140 106006 010 020 000 00
072530 2352N 08120W 6971 02519 9266 +190 +135 230011 018 020 001 00
072600 2351N 08119W 6970 02528 9268 +197 +132 242026 031 022 001 03
072630 2350N 08117W 6971 02541 9285 +192 +140 233040 046 052 002 03
072700 2349N 08115W 6956 02577 9310 +183 +145 225058 064 071 002 00
$$
;

[Aric Dunn]

Seems to me Irma is walking off that shear for the moment. She may have about a 6-8 hour window to intensify significantly Aric.

it is a big system.. but pressure is pressure.. you can already see the tilt .. it will limit the intensification .. unless something changes. right now the the upper/mid level circ is not all that aligned..

very clear. https://weather.msfc.nasa.gov/goes/abi/ ... and14.html run loop you can see the inflow at the lower level .. the eye will not clear out like that..

[Bunkertor]

Thought, i imgur one, too

[northjaxpro]

00Z GFS bombs out Irma at 911 mb @ 18Z this afternoon as she landfalls between Fort Myers and Naples.

[northjaxpro]

Yeah, Aric I can see the issue of the vertical alignment with the inner core on that image you gave above.

[caneman]

According to Dennis Phillips the significant weaking won't occur from shear til North of Tampa

[AJC3]

06Z GFS bombs out Irma at 911 mb @ 18Z this afternoon as she landfalls between Fort Myers and Naples.

You mean the 00Z GFS. The 06Z cycle won't be running for another couple hours.

[bob rulz]

Maybe that will keep it from RI, but it won't keep it from steady intensification. Could still drop a few mb and gain 10mph before landfall imo. And I still wouldn't be surprised to see it gain more, either.

[caneman]

06Z GFS bombs out Irma at 911 mb @ 18Z this afternoon as she landfalls between Fort Myers and Naples.

You mean the 00Z GFS. The 06Z cycle won't be running for another couple hours.

Thoughts on the shear AJ? How much more strengthening if any, when would it start to weaken?

[AJC3]

06Z GFS bombs out Irma at 911 mb @ 18Z this afternoon as she landfalls between Fort Myers and Naples.

You mean the 00Z GFS. The 06Z cycle won't be running for another couple hours.

Thoughts on the shear AJ?

Looks legit based upon the position of the short wave trough. The issue is twofold. 1. The shear is divergent, which isn't nearly as detrimental and tends to enhance poleward outflow. 2. The well established upper level anticyclone should be able to fight off the shear initially.

Still, the southern eyewall has remained open for several hours now. We'll see what the next few hours brings...

[Sciencerocks]

000
URNT15 KNHC 100737
AF302 2911A IRMA HDOB 47 20170910
072730 2349N 08113W 6966 02592 9336 +188 +124 216074 076 085 002 03
072800 2348N 08112W 6967 02615 9383 +162 +136 220088 097 102 003 00
072830 2347N 08110W 6955 02667 9455 +129 //// 222111 115 104 006 01
072900 2346N 08108W 6974 02679 9486 +134 +125 213116 118 100 008 00
072930 2345N 08107W 6957 02727 9517 +132 +124 210114 118 097 008 00
073000 2345N 08106W 6974 02733 9569 +112 //// 208111 113 090 012 01
073030 2344N 08104W 6959 02774 9590 +116 //// 207108 110 084 009 01
073100 2343N 08103W 6961 02792 9624 +106 //// 208103 106 080 010 01
073130 2342N 08101W 6967 02802 9644 +104 //// 206103 104 076 010 01
073200 2342N 08100W 6965 02817 9648 +114 +099 207099 102 075 010 00
073230 2341N 08059W 6961 02837 9662 +115 +101 208095 097 074 008 00
073300 2340N 08057W 6967 02843 9670 +120 +101 208091 093 073 006 00
073330 2339N 08056W 6965 02857 9684 +120 +107 207090 091 071 006 00
073400 2339N 08054W 6961 02873 9692 +123 +107 208088 089 070 005 00
073430 2338N 08053W 6967 02876 9691 +137 +099 207085 088 067 005 00
073500 2337N 08051W 6958 02898 9707 +132 +099 209082 085 065 004 00
073530 2336N 08050W 6964 02898 9718 +130 +098 210080 081 064 003 00
073600 2335N 08048W 6969 02902 9720 +135 +102 209079 080 064 001 00
073630 2335N 08047W 6962 02916 9731 +131 +105 207079 079 063 001 00
073700 2334N 08045W 6961 02924 9734 +134 +110 207078 079 060 002 00
$$
;

[northjaxpro]

Yes the 0Z GFS is what I meant, sorry gang!! It is 3:45 a.m. and I guess I am half asleep following Irma lol...