NZ Weather Forum

looks like a new TC is forming?

Yes, JTWC this morning raised the chances of the tropical low near Vanuatu becoming a TC in the next 12-24 hours from medium to high.

JTWC have also issued a TC Formation Alert, with some interesting wording...

Upper-level analysis reveals extensive poleward and equatorward outflow, low to moderate (10-20 knot) vertical wind shear, and a zesty 29-30C sea surface temperature, paint the picture of a very conducive environment for tropical development.

they must be bored lol

Fiji Met expecting to name our developing tropical low by morning...

JTWC has issued their first TC advisory and track-map...

Looking good with increasing deep convection overnight and decreasing wind shear. Should be named fairly soon.

Hmm... Unlike JTWC, Fiji Met not yet convinced this low has reached TC status.

potential for it to be able to follow the departing high pressure (that is coming in) and head down this way
timing is crucial and a lot of variables

TC Fili was named by Fiji Met this afternoon. So thought it might warrant its own thread.

Westerly wind shear due to the subtropical jetstream running aloft was a little stronger than expected today, displacing convection to the east of Fili's LLCC. Despite that, convection has still ramped up today and, with plenty of moisture and shear easing, Fili should peak tomorrow before cooler SST's begin to take their toll.

Fili was upgraded to Cat 2 by Fiji Met this morning and expected to peak at Cat 3 by tomorrow morning.

latest Euro model run as it hitting the NI next tuesday as a strong ex TC
so one to watch!

And ukmo has it coming down in the Tasman. One to watch for sure

GFS has been the best performer out of the main models for this system over the last 7 days.

Fili's robust convection earlier today has been hindered by dry air entrainment from the west this afternoon. However, with relatively lower shear over the next 12 hours, Fiji Met are still hopeful that Fili may reach Cat 3 by morning, although JTWC not so optimistic. After that, increasing shear and cooler SST's should see a gradual weakening in Fili's intensity. Fiji Met currently have Fili with a peak of 60 kt max winds and central pressure down to 977 hPa.

The ACCESS (UKMET?) Model is very aggressive with a very deep ex TC passing over the NI

Early forecasts mean nothing, but East Coast could get a battering next week. Hopefully FILI stays offshore and kicks up some nice clean waves. Keeping an eye on the models, and one eye on the surf forecasts.

Central deep convection has flared and expanded overnight. However, Fili's feeder bands have also unraveled and fragmented, especially along its southern flank where shear is stronger. Fili will probably begin extratropical transition in the next 24-36 hours and may even dissipate before then as it encounters an increasingly harsh environment.

Latest GFS is pretty committed to a line over or near the NI, the Euro split between a curve to the northeast then death in the sub-tropics, and a passage over the seas north of the ni.

Dry air and high southwesterly shear taking its toll on Fili today, with deep central convection being sheared to the east of its partially exposed LLCC. Fiji Met have max winds down to 50 kts and central pressure up to 986 hPa.

Fili downgraded to Cat 1 overnight by Fiji Met with 45 kt max winds. Deep convection well sheared to the east of its partially exposed LLCC.

none of the models can agree currently on exact the future movement
It seems to be holding a SE course more than the models had predicted..so far

GFS indicates that x Fili will cross over the North Island on last nights map

Fili looks to have veered a little more south from its earlier predicted SE course. Model consensus also now more in agreement, with it looking increasingly more likely that after transition Fili will reintensify as a formidable subtropical low, before impacting the North Island from next Tuesday to Thursday. Might need another thread for that though.