BoB: AMPHAN - Post-Tropical

[doomhaMwx]

Probably faster intensification now? Looks like Amphan is still able to fend off the swath of dry air to its west. It's probably not an issue, or maybe "not yet".

[Hayabusa]

UKMET 17/00z has 899 mb peak

[Nancy Smar]

SALIENT FEATURES:-
VORTEX (AMPHAN) OVER SE BAY & N/HOOD :-
VORTEX (AMPHAN) OVER CENTRAL PARTS OF SOUTH BAY & N/HOOD HAS
FURTHER INTENSIFIED NOW LAY CENTERED NEAR 11.7N/86.0E (.) A BANDING
EYE IS OBSERVED IN THE VISIBLE IMAGERY. INTENSITY T4.0 RPT T 4.0 (.)
CURVED BAND PATTERN (.) ASSTD BKN LOW/MED CLOUDS WITH EMBDD INT
TO V INT CONVTN OVER BAY BET LAT 7.5N TO 14.0N LONG 81.0E TO 89.0E
(.)

The latest Dvorak analysis from IMD is T4.0 so that Amphan could be classified as a VSCS later today.

Very Severe Cyclonic storm AMPHAN lies over central parts of south Bay of Bengal. To intensify into Extremely severe cyclonic storm during next 24 hours and cross West Bengal and Bangladesh coast during 20th afternoon/evening.

[Abdullah]

UKMET 17/00z has 899 mb peak

Where can you find the UKMET for the North Indian Ocean (in graphic preferably)? I've heard they're good with intensity.

[Nancy Smar]

UKMET 17/00z has 899 mb peak

Where can you find the UKMET for the North Indian Ocean (in graphic preferably)? I've heard they're good with intensity.

https://tgftp.nws.noaa.gov/data/raw/fx/fxxt04.egrr..txt

[Abdullah]

The storm is now called "Very Severe Cyclonic Storm Amphan"

UKMET 17/00z has 899 mb peak

Where can you find the UKMET for the North Indian Ocean (in graphic preferably)? I've heard they're good with intensity.

https://tgftp.nws.noaa.gov/data/raw/fx/fxxt04.egrr..txt

Anywhere I can convert this to a graphic? I can make do without, but I'd like to see that (I've seen others on this website).

[Hayabusa]

The storm is now called "Very Severe Cyclonic Storm Amphan"

Where can you find the UKMET for the North Indian Ocean (in graphic preferably)? I've heard they're good with intensity.

https://tgftp.nws.noaa.gov/data/raw/fx/fxxt04.egrr..txt

Anywhere I can convert this to a graphic? I can make do without, but I'd like to see that (I've seen others on this website).

I plot the UKMET into a graphic if you mean the ones I post in this thread.

[Abdullah]

The storm is now called "Very Severe Cyclonic Storm Amphan"

https://tgftp.nws.noaa.gov/data/raw/fx/fxxt04.egrr..txt

Anywhere I can convert this to a graphic? I can make do without, but I'd like to see that (I've seen others on this website).

I plot the UKMET into a graphic if you mean the ones I post in this thread.

https://i.imgur.com/DrwpFW3.png

https://i.imgur.com/e0F2Rpq.png

Perfect! Thanks for doing this!

[aspen]

The GFS is back to being aggressive with Amphan and forecasts a 933 mbar storm near landfall. The Euro goes down to 939 mbar and ICON goes even further to 928 mbar, the lowest I’ve seen from it in a long time. While the Euro has Amphan peak near landfall, the ICON and the GFS runs predict peak intensity in the 12-24 hours before landfall, with the storm weakening afterwards.

The HWRF has calmed down a bit and “only” shows a 929 mbar peak. However, this is right at landfall in Bangladesh.

[aspen]

10:29z microwave pass shows an almost complete eyewall. If it fully solidifies and keeps itself stable, then we could see a phase of RI commence later today.

https://rammb-data.cira.colostate.edu/t ... 171029.gif

[Abdullah]

Pressure down to 975 millibars as of 12Z best track.

I can't find any info for pressure on the JTWC or IMD sites, though.

[aspen]

The storm is now called "Very Severe Cyclonic Storm Amphan"

https://tgftp.nws.noaa.gov/data/raw/fx/fxxt04.egrr..txt

Anywhere I can convert this to a graphic? I can make do without, but I'd like to see that (I've seen others on this website).

I plot the UKMET into a graphic if you mean the ones I post in this thread.

https://i.imgur.com/DrwpFW3.png

https://i.imgur.com/e0F2Rpq.png

What’s the pressure at 20N? That looks like it’s sub-900 mbar.

[Highteeld]

Eyewall isn't balanced, but it's closed. Probably 80 knots if i had to guess intensity

[Hayabusa]

The storm is now called "Very Severe Cyclonic Storm Amphan"



Anywhere I can convert this to a graphic? I can make do without, but I'd like to see that (I've seen others on this website).

I plot the UKMET into a graphic if you mean the ones I post in this thread.

https://i.imgur.com/DrwpFW3.png

https://i.imgur.com/e0F2Rpq.png

What’s the pressure at 20N? That looks like it’s sub-900 mbar.

It's 899 mb, that's the lowest pressure also labeled on the 2nd plot graphic but on the 1st graphic the annotation is based on the max wind which in this case 105 kt at 900 mb.

[Abdullah]

The storm is now called "Very Severe Cyclonic Storm Amphan"



Anywhere I can convert this to a graphic? I can make do without, but I'd like to see that (I've seen others on this website).

I plot the UKMET into a graphic if you mean the ones I post in this thread.

https://i.imgur.com/DrwpFW3.png

https://i.imgur.com/e0F2Rpq.png

What’s the pressure at 20N? That looks like it’s sub-900 mbar.

899.0 millibars.

[Highteeld]

01B
TROPICAL CYCLONE 01B 12:00UTC 17May2020
UW-CIMSS Experimental Vertical Shear and TC Intensity Trend Estimates

Current Conditions (from JTWC) :
Latitude : 12:09:06 N
Longitude : 86:24:00 E
Intensity (MSLP) : 976.0 hPa

Max Pot Int (MPI,from Emanuel) : 890.0 hPa
MPI differential (MSLP-MPI) : 86.0 hPa

CIMSS Vertical Shear Magnitude : 8.5 m/s (16.5 kts)
Direction : 127.8 deg

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

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

[1900hurricane]

The eyewall is much better on the NOAA-19 pass for sure, and you can see the effects of this on satellite imagery now. Amphan is once again firing an extensive area of -80ºC or colder tops over the center. The dry air does still lurk about though. You can easily see the green wedge of it to the north and west of the TC, and it continues to wrap around in a more diluted state to the south, as seen in the lighter hues of blue. The large circulation has drawn in the dry air mass and slowed its early rapid development, bit it appears to have done a fairly good job mixing it out for now.

As Amphan moves north, it is going to be in a very good position to diagnose any kind of undercutting shear with the Point Blair sounding site in the Nicobar Islands immediately upstream. The obs are worth keeping an eye on for sure.

Intensity wise, I feel like JTWC has been running a little low in general with Amphan. Early Dvorak analyses were too low in my opinion, and that may have put them behind the curve from the start. Now, microwave estimates are coming in considerably higher than the JTWC estimates, even with RMWs that appear very reasonable to me (28 km/15 nm from JTWC for the 0403Z METOP-A estimate of 89 kt/960 mb). This potential discrepancy in intensity analysis is probably throwing off some of the more reliable statistical intensity guidance like SHIPS and LGEM, and Amphan is probably stronger right now than either of those solutions ever indicate. On the opposite extreme, the CHIPS members are going full Tip Black Hole and likely way overdoing intensity due to some of the limiting factors discussed above. Overall, I think the HWFI/HWRF intensity estimates (wind, not necessarily pressure) may have the best overall handle, and I would probably lean those number pretty hard. The 12Z HWFI goes up to 121 kt, which I think is very reasonable given the current picture, although given that I think the current estimate is a little lowballed, I might move it up 12-24 hours up in time frame, from tau 48 to tau 24-36.

[SouthDadeFish]

Recent convective trends are concerning. I think RI is a distinct possibility over the next 24-36 hours.

 https://twitter.com/MikeFischerWx/status/1262029102573330433

[aspen]

The eye is starting to open up. There are already a couple of W pixels on Dvorak imagery: https://rammb-data.cira.colostate.edu/t ... 171400.jpg

[aspen]

W eye with B pixels inside a CDG ring...perhaps 90-100 kt now?

https://rammb-data.cira.colostate.edu/t ... 171500.jpg