NIO: OCKHI - Post-Tropical

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euro6208
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Re: NIO: OCKHI - Severe Cyclonic Storm

#21 Postby euro6208 » Fri Dec 01, 2017 8:44 am

wxman57 wrote:Remember, the JTWC is not the official RSMC for any basin. The IMD is the RSMC. They are still classifying Ockhi as a tropical storm (severe tropical cyclone). I'm not saying they're correct, but they're the official source. I think winds are in the 70-80 kt range now.


Yes we know that but JTWC uses the 1 min average winds that we are accustomed to. Only CPHC and NHC carries this. So it's a good comparison to the other agencies...IMD...JMA...BOM...ETC.
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Re: NIO: OCKHI - Severe Cyclonic Storm

#22 Postby 1900hurricane » Fri Dec 01, 2017 9:00 am

IMD used 3 minute sustained winds, which is very similar to the 1 minute sustained winds used by the American tropical forecasting agencies. In fact, the NHC/CPHC/JTWC and IMD Dvorak tables are nearly identical (from here).

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Re: NIO: OCKHI - Severe Cyclonic Storm

#23 Postby euro6208 » Fri Dec 01, 2017 9:14 am

No one is saying that JTWC is the official agency. Here in the WPAC, you always hear how it isn't the official agency. Just deal with it. Truth is 1 min will always lead JMA's 10 min winds. JMA calling a 60 knot TS is already a 1 min typhoon when converted. The disparity grows as a system becomes stronger.
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Re: NIO: OCKHI - Severe Cyclonic Storm

#24 Postby 1900hurricane » Fri Dec 01, 2017 1:20 pm

Structure remains pretty good, but dry air is indeed wrapping in from the west, as I suspected.

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Re: NIO: OCKHI - Severe Cyclonic Storm

#25 Postby Imran_doomhaMwx » Fri Dec 01, 2017 5:32 pm

Minicoy island in the southern Lakshadweep islands has been raked by the eyewall of Cyclone Ockhi, as its eye/center passed just to the north. At 09Z(2:30pm IST) Friday, a station in Minicoy recorded a westerly wind speed (appears to be sustained winds) of 120kph and a SLP of 989mb.

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A microwave image from earlier.
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Re: NIO: OCKHI - Very Severe Cyclonic Storm

#26 Postby Imran_doomhaMwx » Sat Dec 02, 2017 1:20 am

IMD calling this a Very Severe Cyclonic Storm.
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Re: NIO: OCKHI - Severe Cyclonic Storm

#27 Postby mrbagyo » Sat Dec 02, 2017 1:31 am

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Re: NIO: OCKHI - Very Severe Cyclonic Storm

#28 Postby Imran_doomhaMwx » Sat Dec 02, 2017 3:47 am

Category 2 by JTWC since 00Z today...
03B OCKHI 171202 0000 9.4N 71.5E IO 85 970
03B OCKHI 171202 0600 9.9N 71.0E IO 85 959


Lookin' quite impressive! :

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Re: NIO: OCKHI - Severe Cyclonic Storm

#29 Postby Digital-TC-Chaser » Sat Dec 02, 2017 5:57 am

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Updated: 2017-12-02T10:52:03Z
ECMWF ENSEMBLE Tropical Cyclones and Disturbances 2017120200
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Re: NIO: OCKHI - Severe Cyclonic Storm

#30 Postby Imran_doomhaMwx » Mon Dec 04, 2017 5:18 am

Ockhi weakening over the eastern Arabian Sea...

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Re: NIO: OCKHI - Severe Cyclonic Storm

#31 Postby Imran_doomhaMwx » Mon Dec 04, 2017 5:22 am

Heavy rainfall threat is still there for southern Gujarat state and northern Maharashtra state, however... Some coastal areas may see total rain accumulations near 100mm(4in) until Wednesday morning/afternoon IST.

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Re: NIO: OCKHI - Severe Cyclonic Storm

#32 Postby Digital-TC-Chaser » Mon Dec 04, 2017 10:19 pm

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With the shear and cool water ahead this system may not be a cyclone @ landfall.
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Re: NIO: OCKHI - Severe Cyclonic Storm

#33 Postby Imran_doomhaMwx » Tue Dec 05, 2017 3:50 pm

Nothing much left...

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Re: NIO: OCKHI - Severe Cyclonic Storm

#34 Postby CrazyC83 » Tue Dec 05, 2017 9:12 pm

Imran_doomhaMwx wrote:Minicoy island in the southern Lakshadweep islands has been raked by the eyewall of Cyclone Ockhi, as its eye/center passed just to the north. At 09Z(2:30pm IST) Friday, a station in Minicoy recorded a westerly wind speed (appears to be sustained winds) of 120kph and a SLP of 989mb.

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A microwave image from earlier.


That suggests the minimum pressure (or at least at that time) was 982mb, due to the uncertainty of the sustaining period. I'd estimate that 85 kt is a reasonable peak intensity given that reading and the minimal structural change afterward (given the low latitude and fast motion, 982 would likely translate to cat 2).
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Re: NIO: OCKHI - Severe Cyclonic Storm

#35 Postby 1900hurricane » Wed Dec 06, 2017 12:00 am

CrazyC83 wrote:
Imran_doomhaMwx wrote:Minicoy island in the southern Lakshadweep islands has been raked by the eyewall of Cyclone Ockhi, as its eye/center passed just to the north. At 09Z(2:30pm IST) Friday, a station in Minicoy recorded a westerly wind speed (appears to be sustained winds) of 120kph and a SLP of 989mb.

[images removed]
A microwave image from earlier.


That suggests the minimum pressure (or at least at that time) was 982mb, due to the uncertainty of the sustaining period. I'd estimate that 85 kt is a reasonable peak intensity given that reading and the minimal structural change afterward (given the low latitude and fast motion, 982 would likely translate to cat 2).

Here's what I got using your 982 mb pressure estimate and other info from the b-deck using KZC:

Using a 982 mb central pressure, 9 kt forward speed,
74 nm average TS radius, and 8.8º latitude, KZC outputs
a 73 kt 1 min wind velocity with an OCI of 1008 mb.


The 06Z estimate from December 1st was 70 kt, which looks fairly reasonable at that moment in time to me.
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