Tropical & Extra Tropical cyclone season 2017/18

[Cyclone Tracy]

TC FEHI struggling with wind shear but still maintaining a Cat 1 status. Starting to approach 26c Sea surface temperatures. Transition to an extratropical cyclone likely to occur within the next 30 hours.

[NZ Thunderstorm Soc]

Transition to an extratropical cyclone likely to occur within the next 30 hours.

Why do they call it an extratropical cyclone ?
What does extratropical mean?
The newreader on RNZ at 4am this morning whist reading the marine or shipping forecast read out the situation and when coming across the word extratopical regarding TC Fehi, she said "whatever that means"

[Willoughby]

Transition to an extratropical cyclone likely to occur within the next 30 hours.

Why do they call it an extratropical cyclone ?
What does extratropical mean?
The newreader on RNZ at 4am this morning whist reading the marine or shipping forecast read out the situation and when coming across the word extratopical regarding TC Fehi, she said "whatever that means"

Have a read here:
http://www.aoml.noaa.gov/hrd/tcfaq/A7.html

[Cyclone Tracy]

TC Fehi is now in transition ET phase and will be an ex tropical cyclone very soon. Upper level winds have increased and initial interaction with the jet stream has commenced.

Refer to NZ thread associated with its further path as an extratropical cyclone viewtopic.php?f=2&t=5784

[Cyclone Tracy]

Signs of a large tropical depression below the south pacific convergence zone around 8th February on today EC ensemble 12z, one to keep an eye on

[Cyclone Tracy]

An invest 97P is now in place for a likely tropical depression to form in the next 48 hours. Low is showing small signs of circulation with sustained winds of 15 knots around the forming LLCC near Vanuatu. Ensembles across EC and GEFS of 72 members are quite in sync to around 168 hours. EC ensemble now starting to show low possibilities of a strong cyclone within 8 days.

Longer term impact on NZ as normal will depend on the position and strength of the High pressure ridge. GFS of multiple runs has an impact on the upper North Island around Feb 16 and 17 but this is a low level of confidence IMO this far out. Current water temperatures around the upper NI are between 24 to 25c, this is around 3 to 4c above normal.

[Cyclone Tracy]

Early signs of a possible tropical disturbance near Fiji, Vanuatu and New Caledonia in early March are starting to appear on the EC ensemble 2102 12Z.

[03Stormchaser]

Early signs of a possible tropical disturbance near Fiji, Vanuatu and New Caledonia in early March are starting to appear on the EC ensemble 2102 12Z.

Any update on this? And where can you access these models?

[Cyclone Tracy]

Latest EC ensemble 2402 12Z increases chances of a tropical disturbance becoming a depression in early to mid March near Fiji, Vanuatu and New Caledonia as the Walker cell shows signs of a pulse.

@03Stormchaser , it's on a subscription only membership and not freely available.

[Willoughby]

No need to really pay - the data is also here for free: https://weather.us/model-charts/euro/gr ... 1200z.html

[Cyclone Tracy]

No need to really pay - the data is also here for free: https://weather.us/model-charts/euro/gr ... 1200z.html

It only gives the main EC model on a 48 hour projection on the probability analysis though , unless I'm missing something?

[Willoughby]

It only gives the main EC model on a 48 hour projection on the probability analysis though , unless I'm missing something?

The probability sets of what they offer is from the EC Ensemble Prediction System - same with the Extreme Forecast Index charts - so same data just different time appropriation.

[03Stormchaser]

No need to really pay - the data is also here for free: https://weather.us/model-charts/euro/gr ... 1200z.html

Cheers Will

[Cyclone Tracy]

EC ensemble run 25102 12Z showing a likely depression around Nth Queensland in 48 to 96 hours, also becoming a chance south of Fiji as well. Becoming cyclones in the 144 to 240 hours is still unlikely at this stage.

[Cyclone Tracy]

EC ensemble run 0903 12Z showing a likely tropical depression near the Solomon Islands moving SW and a cyclone becoming more likely by 96 to 144 hours. If a cyclone were to develop, the ridge position would force it SW towards SE Queensland. After this point, global models disagree on whether it rounds the ridge towards NZ or becomes a landphoon over Australia.

[Cyclone Tracy]

JTWC now classifying the tropical depression south of he Solomon Islands as a Tropical cyclone. BoM use a different criteria and if met, she will be named Linda. She will be up against some brutal wind shear in the coming days, so is likely to be shredded as she moves close to Queensland.....but if she stalls, environments can change

[Cyclone Tracy]

Tropical cyclone Linda has been born

[jamie]

The Aussie Facebook pages are analysing this one to death.

[Willoughby]

The Aussie Facebook pages are analysing this one to death.

It's all a bit ridiculous.

[Cyclone Tracy]

TC Linda currently being shredded like a cabbage. Won't be a cyclone for too much longer. It's been a quiet season so far in the Coral sea, making the Queenslanders get a little too excited when something spins

MJO is missing in action and will be for another week or so but the equatorial Rossby wave continues to increase the cross-equatorial flow. NT and WA could have a decent cyclone on their hands soon. There is also increasing chances of another tropical disturbance around the Solomon islands in the next 8 to 10 days with the flow continuing. IMO, I'm starting to see signs of a big finish to the TC season below the south pacific convergence zone from the end of March.

[Willoughby]

Expecting something close to here shortly:

JTWC:

(2) AN AREA OF CONVECTION (INVEST 92S) HAS PERSISTED NEAR
10.5S 134.4E, APPROXIMATELY 235 NM EAST-NORTHEAST OF DARWIN,
AUSTRALIA. ANIMATED ENHANCED INFRARED SATELLITE IMAGERY DEPICTS
PERSISTENT FLARING CONVECTION ABOVE A BROAD, CONSOLIDATING LOW LEVEL
CIRCULATION CENTER. VERTICAL WIND SHEAR IS LOW (10 KNOTS) DUE TO A
POINT SOURCE OVER 92S THAT IS FUELING ADEQUATE DIVERGENCE ALOFT. SEA
SURFACE TEMPERATURES ARE VERY WARM (27-29 CELSIUS) AND WILL SUPPORT
FURTHER DEVELOPMENT. GLOBAL MODEL GUIDANCE FAVORS 92S REACHING
TROPICAL STORM STRENGTH AFTER TAU 24 AS IT REMAINS QUASI-STATIONARY
BEFORE TRACKING SOUTHWEST. HOWEVER, THERE EXISTS SOME UNCERTAINTY
WHETHER 92S WILL TRACK OVER WATER ALONG THE COAST OR OVER LAND.
MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS.
MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE
POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE
WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.

http://www.bom.gov.au/products/IDR772.loop.shtml#skip

EC and ICON solutions looking the most realistic at this point.

[Cyclone Tracy]

and there it is. TC watch now in place for the N.T. Chances of a St Pat's day TC for Darwin looking more likely.

[Cyclone Tracy]

Tropical disturbance chances continue to increase around March 26th south of the Solomon Islands with a possible cyclone now a low chance soon after on the EC ensemble 1503 12Z run.

[Cyclone Tracy]

EC ensemble 1803 12Z becoming confident of a tropical depression around the Solomon Islands TD breeding ground by Thursday and increases chances of a Tropical cyclone to affect New Caledonia by the weekend.

[Cyclone Tracy]

Next in line from the current Monsoon trough over northern Oz. Significant cross equatorial flow is pushing into a strong south easterly flow making the monsoonal lows spin hard when they get going.

She will be named TC Nora if all goes according to plan and will be a gulf beast quite quickly with the projected favourable conditions.