Tropical cyclone - EX-TC season 2019-20 Sth Pacific / Oz

[Cyclone Tracy]

It's that time of year again with the official 2019/20 season kicking off this Friday 1st November. NIWA and Fiji Met are forecasting around average for the South Pacific while the BoM are going for below normal in its jurisdiction.

[Cyclone Tracy]

All models starting to show a strengthening south pacific convergence zone nearer to the equator by the end of this week. Current sea surface temperatures in this region are around 30c with the 26c line dropping now down to 20 degrees south of the equator. The South Pacific tropics are starting to move into summer mode.

SPCZ 22 Nov.jpg

Water temp 1711.jpg

[Awhituobs]

I notice a cooler than normal SST in the Coral sea currently?

[Cyclone Tracy]

Invest 90P is now being monitored by multiple agencies near the Solomon Islands. Low pressure at 1006 hPa, winds around 10 to 15 knots. Deep convection north and north west of the circulation with cloud tops pushing through -100c. Conditions will become more favourable early next week with less wind shear in the region. Vanuatu will be watching closely.

Invest 90P.jpg

[Jarrodrin]

What are the odds of this cyclone clearing up before Tuesday?

[Nev]

Fiji Met expect TD 01F/90P to be named by tomorrow morning and a Cat 2 by Tuesday morning.
JTWC also issued a TC Formation Alert yesterday arvo.

TD 01F-90P Nadi Track-map - Nov 23, 1322z.png

TD 01F-90P Hima rb - Nov 23, 1600z.JPG

[Awhituobs]

that will be the earliest TC for some years?

[Nev]

that will be the earliest TC for some years?

Yes, except for TC Liua named on Sep 27 last year - the earliest-forming TC on record in the South Pacific.

[Awhituobs]

I forgot about that one
but that one was a real outlier...not even in the normal season

[Nev]

TC Rita was named by Fiji Met this evening.

TC Rita - Nadi Track-map - Nov 24, 0847z.png

TC Rita - JTWC Track-map - Nov 24, 0900z.gif

[Cyclone Tracy]

Rita is looking much stronger this morning with low vertical wind shear assisting, Archer / Dvorak method currently have her near 60 knots and getting closer to Cat 2 (Cat 1 Hurricane) status. Wind shear should shred her by mid week but there is quite a bit of uncertainty on her track 72 hours from now.

[Cyclone Tracy]

Rita is still a little ugly but showing signs that her core is warming along with a couple isolated lightning strikes as she attemps to build an eyewall.

Edit: Latest satellite max wind estimation is coming in around 65 knots (1 min sustained) which unofficially puts her well into Cat 2 Fijian scale level.

TC Rita 1.30pm NZT 2511.jpg

[Nev]

Wow! Fiji Met also upgraded Rita to a high end Cat 2 this arvo and expect this little midget to tip Cat 3 tonight.

TC Rita - Nadi Track-map - Nov 25, 0148z.png

[Nev]

Cat 3 now, just 24 hours after being named…

TC Rita - Nadi Track-map - Nov 25, 0729z.png

[Cyclone Tracy]

Interesting 7 day adjustment for sea surface temperatures. Sub-tropics / mid latitude wise, the large polar low is currently stabilising the Tasman sea temps and the formidable positive IOD is starting to break down NW of OZ. No clear sign of the cross equatorial flow to kick start the Australian monsoon but a large monsoon gyre has dropped to the south east of the Philippines in the last few days.

5 Dec 7 day SST.jpg

[Awhituobs]

different readings:
https://www.weatherzone.com.au/climate/ ... jsp?c=ssta

ah I see now your chart is the change data

[Cyclone Tracy]

EC and a few other models are starting to hint at some cross equatorial flow around Christmas relating to the monsoon trough including a weak north westerly flow from Indonesia towards Australia. Still hard to tell when the monsoon trough will move into the southern hemisphere but smalls signs are starting to appear. The South Pacific convergence zone also slightly intensifies in the same period.

Monsoon trough SPCZ.jpg

[Nev]

Mod Note: See separate thread for TC Sarai named today.

[Cyclone Tracy]

Monsoon trough well on the way into the southern hemisphere by early next week under the MJO influence. Invest 91S now in place for a disturbance south of Indonesia. A second disturbance to the east of Darwin also may have to be looked at closely. The BoM could become busy next week around the tropics.

[Cyclone Tracy]

Invest 91S now officially a tropical Low off W.A. Should become Tropical cyclone Blake tomorrow evening NZT.

[Cyclone Tracy]

Invest 92S is now up and running for the tropical depression currently 350km NE of Darwin. Latest EC 18Z run continues to produce a cat 1 around 250 km NE of Darwin late Thursday evening local time. The 18Z run has moved the system 100km closer to the Van Dieman gulf compared to the 12z run.

[Cyclone Tracy]

TC Blake becomes the first named Australian region cyclone of the season.

[Willoughby]

The tropical low centred 32 nautical miles north of Milingimbi, Arnhem Land is expected to be named Claudia tonight and become a threat to northern coast communities.

image.png

Track is eerily similiar to that of damaging TC Marcus that hit Darwin in March 2018.

[Cyclone Tracy]

Yes, I see what you mean. I was looking at the old TC Marcus thread earlier and the Marcus BoM track map is almost identical to the latest map.

Cloud tops are near -95c in the last hour on a hot tower near the circulation centre. Tough system to forecast for the BoM with shear and land friction in play.

[Willoughby]

A chain of redeveloping supercells this afternoon (continuing right now) south of the Warruwi radar site, as the low draws closer. Tornadoes with this activity appears to be highly likely.