BoB: AMPHAN - Post-Tropical

[aspen]

01B AMPHAN 200518 1200 14.0N 86.3E IO 145 901

Called it, but I’m genuinely surprised the JTWC actually went with that. They’ve been doing a great job with Amphan so far.

[Hypercane_Kyle]

Amphan is now the strongest cyclone ever recorded in the Bay of Bengal, beating out the 1999 storm by a significant margin.

[MarioProtVI]

Amphan is now the strongest cyclone ever recorded in the Bay of Bengal, beating out the 1999 storm by a significant margin.

Not yet, you’re going by the JTWC’s pressure (901), which even though I think is a reasonable guess, it is overridden by the IMD (the RSMC of this basin), who has it at 930 pending 12z update which will probably drop to ~920 or so.


This is really shaping up to be the worst storm to impact Bangladesh since then and could potentially kill thousands if preparations are not taken into action. We can only hope it somehow strikes a sparsely popular area that causes few fatalities.

[aspen]

Amphan is now the strongest cyclone ever recorded in the Bay of Bengal, beating out the 1999 storm by a significant margin.

I think I heard about a re-analysis of the Odisha cyclone suggesting it had winds of ~155 kt, so it might’ve been even stronger than Amphan is now.

[mrbagyo]

Triple concentric eyewall?
This EWRC would further increase the radius of maximum wind.

[aspen]

Perhaps the partial third eyewall will blend into the second. That’s what seems to be happening to me.

[Crostorm]

[al78]

An eyewall replacement cycle can be a double edged sword. It lowers the peak wind, but can also increase the radius of damaging winds, which in itself increases the height of the storm surge. I recall this happened with Katrina in 2005, it weakened from cat 5 to cat 3 at landfall but the breadth of the storm grew considerably, and the peak storm surge was near 30 ft.

Does anyone know how effective the cyclone warning and evacuation systems are in the Ganges delta, and what tghe capacity of the shelters is compared to the number under threat?

[doomhaMwx]

VIS satellite shot at sunset
05-18-2020 11:45am UTC

[Yellow Evan]

2020MAY18 001500 5.5 950.8 102.0 5.5 5.7 6.8 1.7T/6hr OFF OFF OFF OFF -44.87 -85.71 EYE -99 IR -15.5 13.25 -86.44 ARCHER MSG1 53.4
2020MAY18 004500 5.5 950.8 102.0 5.5 5.8 6.8 1.7T/6hr OFF OFF OFF OFF -44.29 -85.22 EYE -99 IR 70.9 13.25 -86.42 ARCHER MSG1 53.3
2020MAY18 011500 5.7 942.3 107.2 5.7 6.1 6.9 1.7T/6hr OFF OFF OFF OFF -41.20 -85.18 EYE 7 IR 70.9 13.26 -86.41 ARCHER MSG1 53.3
2020MAY18 014500 5.7 942.3 107.2 5.7 6.2 6.9 1.7T/6hr OFF OFF OFF OFF -36.21 -84.72 EYE 9 IR 70.9 13.27 -86.38 ARCHER MSG1 53.3
2020MAY18 021500 5.9 937.7 112.4 5.9 6.4 6.9 1.7T/6hr OFF OFF OFF OFF -39.05 -84.34 EYE 8 IR 70.9 13.31 -86.40 ARCHER MSG1 53.3
2020MAY18 024500 6.1 933.1 117.4 6.1 6.6 6.9 1.7T/6hr OFF OFF OFF OFF -34.46 -84.31 EYE 9 IR 70.9 13.33 -86.35 ARCHER MSG1 53.3
2020MAY18 031500 6.2 930.9 119.8 6.2 6.4 6.7 2.7T/12hr OFF OFF OFF OFF -50.03 -83.96 EYE -99 IR 70.9 13.35 -86.40 ARCHER MSG1 53.4
2020MAY18 034500 6.2 930.9 119.8 6.2 6.4 6.7 2.7T/12hr OFF OFF OFF OFF -47.24 -83.92 EYE -99 IR 70.9 13.37 -86.38 ARCHER MSG1 53.3
2020MAY18 041500 6.3 928.6 122.2 6.3 6.5 6.6 2.7T/12hr OFF OFF OFF OFF -55.38 -83.61 EYE -99 IR 70.9 13.44 -86.40 ARCHER MSG1 53.4
2020MAY18 044500 6.4 926.3 124.6 6.4 6.5 6.6 2.7T/12hr OFF OFF OFF OFF -54.33 -83.34 EYE -99 IR 70.9 13.45 -86.38 ARCHER MSG1 53.4
2020MAY18 051500 6.4 926.3 124.6 6.4 6.6 6.6 NO LIMIT OFF OFF OFF OFF -51.65 -83.33 EYE -99 IR 70.9 13.50 -86.36 ARCHER MSG1 53.3
2020MAY18 054500 6.5 924.0 127.0 6.5 6.6 6.7 2.7T/12hr OFF OFF OFF OFF -46.04 -83.49 EYE -99 IR 70.9 13.52 -86.31 ARCHER MSG1 53.3
2020MAY18 061500 6.5 924.0 127.0 6.5 6.7 6.9 2.7T/12hr OFF OFF OFF OFF -36.46 -84.25 EYE -99 IR 70.9 13.48 -86.31 ARCHER MSG1 53.3
2020MAY18 064500 6.5 924.0 127.0 6.5 6.8 6.9 2.7T/12hr OFF OFF OFF OFF -35.96 -84.32 EYE 8 IR 71.3 13.58 -86.31 ARCHER MSG1 53.3
2020MAY18 071500 6.6 923.2 129.6 6.6 6.8 6.8 NO LIMIT OFF OFF OFF OFF -42.86 -84.13 EYE 7 IR 71.3 13.52 -86.35 ARCHER MSG1 53.3
2020MAY18 074500 6.7 920.6 132.2 6.7 6.9 6.9 NO LIMIT OFF OFF OFF OFF -38.00 -84.32 EYE 8 IR 71.3 13.66 -86.38 ARCHER MSG1 53.4
2020MAY18 081500 6.7 920.6 132.2 6.7 6.9 6.9 NO LIMIT OFF OFF OFF OFF -33.25 -84.36 EYE 9 IR 71.3 13.62 -86.35 ARCHER MSG1 53.4
2020MAY18 084500 6.8 918.1 134.8 6.8 6.9 7.0 3.2T/18hr OFF OFF OFF OFF -30.41 -84.58 EYE 9 IR 71.3 13.65 -86.39 ARCHER MSG1 53.4
2020MAY18 091500 6.8 918.0 134.8 6.8 6.7 6.7 NO LIMIT OFF OFF OFF OFF -49.40 -84.53 EYE -99 IR 71.3 13.75 -86.48 ARCHER MSG1 53.5
2020MAY18 094500 6.8 918.0 134.8 6.8 6.9 7.0 3.2T/18hr OFF OFF OFF OFF -30.41 -84.14 EYE 11 IR 71.3 13.80 -86.44 ARCHER MSG1 53.5
2020MAY18 101500 6.8 918.0 134.8 6.8 7.0 7.1 3.2T/18hr OFF OFF OFF OFF -19.49 -83.20 EYE 10 IR 71.3 13.81 -86.46 ARCHER MSG1 53.5
2020MAY18 104500 6.8 918.0 134.8 6.8 6.9 6.9 NO LIMIT OFF OFF OFF OFF -23.58 -82.22 EYE 11 IR 14.8 13.88 -86.49 ARCHER MSG1 53.6
2020MAY18 111500 6.9 915.4 137.4 6.9 7.1 7.2 3.2T/18hr OFF OFF OFF OFF -6.82 -81.74 EYE 12 IR 39.0 13.91 -86.53 ARCHER MSG1 53.6
2020MAY18 114500 6.9 915.4 137.4 6.9 7.0 7.0 NO LIMIT OFF OFF OFF OFF -15.04 -81.47 EYE 14 IR 39.0 14.01 -86.59 ARCHER MSG1 53.7
2020MAY18 121500 7.0 912.7 140.0 7.0 7.2 7.2 NO LIMIT OFF OFF OFF OFF -4.47 -81.58 EYE 14 IR 39.0 14.07 -86.55 ARCHER MSG1 53.7
2020MAY18 124500 7.0 912.7 140.0 7.0 7.2 7.2 NO LIMIT OFF OFF OFF OFF -3.31 -82.00 EYE 15 IR 39.0 14.12 -86.59 ARCHER MSG1 53.7
2020MAY18 131500 7.0 910.7 140.0 7.0 7.2 7.2 NO LIMIT OFF OFF OFF OFF -2.66 -81.54 EYE 12 IR 39.0 14.20 -86.62 ARCHER MSG1 53.8
2020MAY18 134500 7.1 907.6 143.0 7.1 6.9 6.9 NO LIMIT OFF OFF OFF OFF -14.29 -80.22 EYE 12 IR 39.0 14.29 -86.62 ARCHER MSG1 53.8
Utilizing history file /data2/misc/ADTV9.0/scripts/history/01B.ODT
Successfully completed listing

[Yellow Evan]

Old but ERC progressing. Still badass that the eye managed to warm during it though.

[1900hurricane]

Port Blair, Nicobar Islands 12Z sounding. Classic tropical profile featuring a tropopause/EL higher than 100 mb.

[doomhaMwx]

150kts peak huh

[mrbagyo]

Russia's Elektro-L2 satellite this past morning

[Yellow Evan]

 https://twitter.com/andyhazelton/status/1262361539778170880

[NotoSans]

 https://twitter.com/philipslau681/status/1262412843447533570

[Hayabusa]

UK init at 894 mb

[mrbagyo]

UK init at 894 mb

https://i.imgur.com/LogkIE1.png

https://i.imgur.com/i8my8Ov.png

That UKMET model track is almost a noontime landfall (local time)



Noontime = maximum surge

[Jr0d]

A slight wobble can make a huge difference. If Amphan goes a little east and the Hooghly River is west side of the storm, the surge will be significantly lower or even suck water out lowering the river/sea level.

A little more of an easterly track, the Hooghly River will have a devastating surge that will affect Kolkata.

The best case scenerio will be for the worst of the storm to impact the Sundarban refuge. This still will bring surges up the rivers and into the villages in Bangladesh.

I hope the warnings are getting out and the locals are taking the necessary steps to protect themselves.

[aspen]

Low-res microwave pass from 14z shows the EWRC well in effect: