Tropical Cyclone Yasa

Cyclone Tracy · Unread post by **Cyclone Tracy** » Sun 13/12/2020 19:15

The latest advanced Dvorak technique satellite estimate shows that 05P is now a category 1 tropical cyclone on the South pacific scale.

Nev · Unread post by **Nev** » Mon 14/12/2020 05:33

Yes, our first named TC of the season, TC Yasa, was named by Fiji Met around 2am this morning…

TROPICAL DISTURBANCE ADVISORY NUMBER B5 ISSUED FROM RSMC NADI
Dec 131403 UTC.

TROPICAL CYCLONE YASA CENTRE 995HPA WAS LOCATED NEAR 15.7S 172.3E AT
131200 UTC. POSITION GOOD POOR BASED ON HIMAWARI-8 IR IMAGERY AND
PERIPHERAL SURFACE REPORTS. CYCLONE MOVING SOUTH SOUTHWEST AT ABOUT
5 KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED
AT ABOUT 35 KNOTS.

EXPECT WINDS ABOVE 33 KNOTS WITHIN 180 NAUTICAL MILES IN NE QUADRANT
AND WITHIN 180 NAUTICAL MILES IN SE QUADRANT
AND WITHIN 120 NAUTICAL MILES IN SW QUADRANT
AND WITHIN 120 NAUTICAL MILES IN NW QUADRANT.

DEEP CONVECTION WRAPPING ONTO SUPPOSED LLCC WITH OVERALL ORGANISATION
IMPROVING. SYSTEM LIES UNDER AN UPPER RIDGE IN A LOW SHEARED
ENVIRONMENT WITH GOOD OUTFLOW TO THE SOUTH AND NORTH. CYCLONIC
CIRCULATION EXTENDS UPTO 500HPA. SST IS AROUND 30 DEGREES CELSIUS.
DVORAK ANALYSIS BASED ON CURVED PATTERN, WITH 0.60 WRAP ON LOG 10
SPIRAL, YIELDING DT=3.0. MET AND PT AGREE. FT BASED ON DT THUS,
YIELDING T3.0/3.0/D0.5/24HRS.

GLOBAL MODELS MOVE THE SYSTEM IN NORTHWARD TRACK AND THEN
SOUTHEASTWARDS WITH FURTHER INTENSIFICATION.

FORECASTS :
AT 12 HRS VALID AT 140000 UTC 16.3S 171.7E MOV SW AT 04 KT WITH 45 KT
CLOSE TO CENTRE
AT 24 HRS VALID AT 141200 UTC 16.2S 171.2E MOV WSW AT 03 KT WITH 50
KT CLOSE TO CENTRE

OUTLOOK :
AT 36 HRS VALID AT 150000 UTC 15.7S 170.8E MOV W AT 02 KT WITH 60 KT
CLOSE TO CENTRE
AT 48 HRS VALID AT 151200 UTC 15.2S 170.8E MOV WNW 02 KT WITH 65 KT
CLOSE TO CENTRE.

THE NEXT TROPICAL DISTURBANCE ADVISORY ON YASA WILL BE ISSUED AROUND
132000 UTC OR EARLIER.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Mon 14/12/2020 08:22

HWRF 12Z projecting a devastating cat 5 eyewall attack on Fiji's Viti Levu this Saturday morning, EC 12Z similar at a high end cat 4.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Mon 14/12/2020 14:39

Developing an eyewall.

Edit: and now upgraded to cat 2.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 15/12/2020 08:08

Core is starting to warm, an eye is appearing.

Nev · Unread post by **Nev** » Tue 15/12/2020 08:42

Yasa just been upgraded to a Severe Cat 3 TC… currently 150 km/h max mean winds and down to 966 hPa according to Fiji Met.

Not looking good for Fiji's main island of Viti Levu on Thu/Fri…

(Edit: As a Cat 5

)

Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 15/12/2020 13:50

Yasa will be loading up with jet fuel on approach to Fiji's Viti Levu with current sea surface temps off the coast 29c and no chance of upwelling weakening. Wind shear is projected to be between 5 to 10 knots over the next 48 hours. Yasa is going to be a top shelf tropical specimen on arrival.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 15/12/2020 14:35

2pm sat pic now giving the ominous truck tyre look. Fiji Met have just upgraded to cat 4, 956 hPa, high 160's km/h wind.

Nev · Unread post by **Nev** » Tue 15/12/2020 16:16

This arvo's track-maps...

Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 15/12/2020 16:50

Quite interesting, both JTWC and Fiji Met are going with EC's 18z path through the middle of the Fijian main Islands which followed the UK's more northern bias in the last couple of days. HWRF and GFS 18Z takes Yasa further south with more land interaction on Viti Levu. HWRF and GFS dropped EC's pants on almost all occasions during the latest Atlantic hurricane season, so this is an interesting call by both agencies.

If Yasa's core moves through the middle of the Islands over water, it will maintain it's strength in the short term and exit SE at a greater speed. Small changes like this can affect longer term paths in the subtropics.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 15/12/2020 21:00

Fiji now coming into the cirrus outflow with the scattering effect producing the classic outer tropical cyclone sunset.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 16/12/2020 05:32

Cat 5, 929 hPa, 205 km/h, gusting to 260 km/h. Core cloud tops have warmed to 8c, crystal clear eye. Yasa is a top shelf.

Awhituobs · Unread post by **Awhituobs** » Wed 16/12/2020 05:37

a Cat 5 before Xmas
wow

Nev · Unread post by **Nev** » Wed 16/12/2020 05:38

And still strengthening…

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 16/12/2020 08:33

Advanced Dvorak satellite estimating method now has Yasa at sustained 132 knots (1 min). 14c core temp. That is now at a Super Typhoon intensity based on that estimate.

tornado · Unread post by **tornado** » Wed 16/12/2020 08:38

Prayers for Fiji. A cat 5 already.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 16/12/2020 11:07

Yasa is now a text book annular tropical cyclone.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 16/12/2020 14:58

Oh boy.....Inner eyewall lightning. Yasa is still maturing.

tornado · Unread post by **tornado** » Wed 16/12/2020 14:59

Cyclone Tracy wrote: ↑Wed 16/12/2020 14:58 Oh boy.....Inner eyewall lightning. Yasa is still maturing.

dam. things are not looking good for fiji.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Wed 16/12/2020 15:57

V-Max has now gone up 140 knots on the ADT method. Yasa is now on the very top shelf and would be a cat 5 Major hurricane on the U.S scale. Pressure down to 914 hPa.

Awhituobs · Unread post by **Awhituobs** » Wed 16/12/2020 17:58

GFS and UKMet? model still has it as a xmas ex cyclone for NZ (flip flopping though)

scottdeb · Unread post by **scottdeb** » Wed 16/12/2020 18:03

Never mind us. Fiji is toast.

Awhituobs · Unread post by **Awhituobs** » Wed 16/12/2020 18:31

Yeah.worse case scenario for them

NZstorm · Unread post by **NZstorm** » Wed 16/12/2020 19:46

EU Wind forecast km/h for 7pm tomorrow. Cyclone moving SE so Nandi may miss it.

Nev · Unread post by **Nev** » Thu 17/12/2020 05:43

Fiji Met currently have Yasa with 240 km/h winds (higher than TC Winston) and down to 906 hPa…

Edit: Updated Nadi Map.

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