BoB: AMPHAN - Post-Tropical

[Hayabusa]

I don't know what were the UKMET's init'd peaks of Mangkhut and Yutu or even Meranti, but this is the first time I saw the UKMET init a TC below 900 mb, not even Hagibis or Halong was able to achieve this, especially Hagibis was predicted by the UKMET to peak at 878 mb.

And btw Amphan is already near MPI...

01B
TROPICAL CYCLONE 01B 12:00UTC 18May2020
UW-CIMSS Experimental Vertical Shear and TC Intensity Trend Estimates

Current Conditions (from JTWC) :
Latitude : 14:12:08 N
Longitude : 86:21:02 E
Intensity (MSLP) : 898.0 hPa

Max Pot Int (MPI,from Emanuel) : 890.0 hPa
MPI differential (MSLP-MPI) : 8.0 hPa

CIMSS Vertical Shear Magnitude : 7.3 m/s (14.2 kts)
Direction : 148.4 deg

Outlook for TC Intensification Based on Current
Env. Shear Values and MPI Differential
Forecast Interval : 6hr 12hr 18hr 24hr
N N N N

Legend : VF-Very Favorable F-Favorable N-Neutral
U-Unfavorable VU-Very Unfavorable

-- Mean Intensity Trend (negative indicates TC deepening) --
6hr 12hr 18hr 24hr
VF <-3.0mb/ 6hr <-6.0mb/12hr <-9.0mb/18hr <-12.0mb/24hr
F -3.0 - -1.5 -6.0 - -3.0 -9.0 - -4.5 -12.0 - -6.0
N -1.5 - +1.5 -3.0 - +3.0 -4.5 - +4.5 -6.0 - +6.0
U +1.5 - +3.0 +3.0 - +6.0 +4.5 - +9.0 +6.0 -+12.0
VU >+3.0 >+6.0 >+9.0 >+12.0

[Yellow Evan]

https://twitter.com/philipslau681/status/1262412843447533570?s=21

Given the uniquely cold cloud tops and the fact that this managed to warm its eye during an ERC, and that the eye was never too warm to begin with, it’s very difficult to say when exactly this peaked or how strong for that matter.

[aspen]

The original eye has completely filled in now. Still waiting on a new microwave pass to see how the core is progressing.

[aspen]

I’m thinking there’s a better possibility of Amphan being able to recover from its EWRC. Not only does it seem to be coming along rather well, but outflow has greatly improved compared to yesterday, so if it stays that way, the new eye could empty itself out.

[qscdefb]

The earlier 15Z MW pass shows a very lopsided outer eyeball, possibly due to wind shear; models are also predicting shear to increase further. If this strong southerly shear is strong enough, it will inhibit restrengthening, and also restrict the eyewall to the navigable semicircle.

[aspen]

A microwave pass at 19z shows the outer eyewall taking over. While it is thin on the east side due to shear, it’s actually coming along a lot better than I would’ve thought; it’s still rather thick and the inner eyewall is almost gone. Perhaps we could see the new eye try to open tonight into tomorrow?

[1900hurricane]

Eyewall replacement has completed, but ENE shear is beginning to make itself known. Recent microwave imagery shows it eating away at the structure on the eastern side. When viewing water vapor imagery, the thunderstorm anvils to the east of Amphan clearly show the shear vector. The shear direction may become slightly more favorable as guidance shows it gaining a more southerly component as Amphan moves north, but that should be canceled out by the increasing magnitude over the same time frame. My expectation is that Amphan will be weakening from here on out.

[mrbagyo]

 https://twitter.com/pppapin/status/1262530539082313729

[aspen]

https://twitter.com/pppapin/status/1262530539082313729?s=19

I don’t think Amphan is going to have much of a core left by landfall...

[1900hurricane]

Shall we begin again?

[aspen]

What an absolute unit

[shah83]

Is it me or is this not going for quite the large eye?

[1900hurricane]

The easterly shear shows up well in the Port Blair sounding from 00Z. Note the wind switch to easterly (towards Amphan) that maxes out around 25 kt around 200 mb. Winds are a little bit weaker up near EL/tropopause, so most of the shear is sliding beneath the anvil.

[doomhaMwx]

Eye showing up on the periphery of Visakhapatnam radar

[1900hurricane]

 https://twitter.com/1900hurricane/status/1262605621192470529

[1900hurricane]

Shall we begin again?

https://i.imgur.com/4nLWt1M.jpg

Indeed we shall.



(I'm referring to eyewall replacement if you didn't pick up on my crypticness)

[mrbagyo]

The moat is clearly visible in this Elektro L2 shot

[mrbagyo]

[doomhaMwx]

Cyclone Amphan is just about 24hrs away from making landfall over the West Bengal. While it's almost certain now that the cyclone will come ashore there, there is still quite a spread among model guidance with regards to where exactly will the eye/center come ashore. The ECMWF is definitely the most western among the model guidance right now, in that it has Amphan passing very very close to the northern Odisha coast tomorrow(Wednesday) before hitting the coast of West Bengal's Purba Mednipur district that is already near the border with Odisha. Landfall over Odisha cannot even be ruled out on the ECMWF solution. The rest of the guidance have Amphan passing farther from the Odisha coast (but likely still close enough to bring hazards there) before hitting the South 24 Paragnas district or near the border with Bangladesh. The forecast tracks from the JTWC and IMD are in between the model solutions.




As far as I'm aware, the coast of northern Odisha is also prone to storm surges just as how prone the Ganges Delta is. However, there are definitely some factors to consider on how high the surge would be if Amphan does come very close there, such as the cyclone's intensity, size, and angle of approach. The 1999 Odisha Cyclone, which hit the northern part of Odisha, set a benchmark of cyclones hitting this area. Amphan will most probably be weaker but it is much larger in size than the 1999 Cyclone. On the angle of approach, Amphan will be moving north/NNE whereas the 1999 Cyclone made landfall while moving northwestward. I'm not really sure how these factors when combined would affect the storm surge there, again if it does come so close just like what the ECMWF shows. I feel that this is worth mentioning since it's the ECMWF model were talking about here, and the potential impacts to Odisha have not been discussed very much. Anyhow, it's definitely time to watch how the cyclone's movement will be during the next 24hrs.

[mrbagyo]

Easterly shear still at it