Tropical & Extra Tropical cyclone season 2017/18

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Cyclone Tracy
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

Another in the queue with a tropical disturbance now likely to be a depression in the next 24 hours near Vanuatu and possible TC IRIS could be born by late in the weekend. Longer term is still very hard to tell but unfavourable wind shear will hinder a TC past 20 degrees south at this stage. This is one to keep an eye on though as remnants of a TD or TC could link with an upper polar trough around NZ late next week.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

TC Nora is born and skips a category and goes straight to 2 in the Gulf of Carpentaria. :smile:

Very favourable wind shear and SST for the next 24 hours.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

TC Nora was actually named by the BoM just after 7am this morn NZDT, then upgraded to Cat 2 just after 1pm this arvo NZDT… :smile:

Track-map from earlier this morning…
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

Nev wrote: Fri 23/03/2018 16:51 TC Nora was actually named by the BoM just after 7am this morn NZDT, then upgraded to Cat 2 just after 1pm this arvo NZDT… :smile:

Track-map from earlier this morning…
Looks like they have re-classified after more data came in. They did this with Kelvin as well in W.A last month which confused everyone when Kelvin went from a 1 to 2 on the crossing point later that day. The new map is Tropical low to Cat 2 where the last L you would expect to be a cat 1 :smile:
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

Nora has been virtually stationary for last the 24 hours (contrary to forecasts), i.e. 0.3 deg east in the last 6 hrs and around a deg east in the last 24 hrs. I think the 'L's shown on BoM's latest map relate to much older positions, and some of the the type actually relates to what's been pancaked or hidden underneath its current position.

P.S. I see she's on the move again and expected to get to Cat 4…
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

Yes, she is gaining momentum quickly now. Interesting divide between the global models at the moment. UK and BOM well east and north of GFS and EC. Plenty of uncertainty after 24 hours on the track.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

invest 95P showing an erupting hot tower this morning west of Vanuatu. Sitting on around 999 hPa, 30 knots sustained winds.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

Has just been named TC Iris by RSMC Nadi this morn…
TROPICAL DISTURBANCE ADVISORY NUMBER A2 ISSUED FROM RSMC NADI
Mar 232005 UTC.

TROPICAL CYCLONE IRIS CENTRE 993HPA WAS LOCATED NEAR 14.3S 163.0E AT
231800 UTC. POSITION POOR BASED ON HIMAWARI-8 IR/EIR IMAGERY AND
PERIPHERAL SURFACE REPORTS. CYCLONE MOVING SOUTHWEST AT ABOUT 7
KNOTS. MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT
ABOUT 40 KNOTS.

EXPECT WINDS OVER 33 KNOTS WITHIN 170 NAUTICAL MILES IN NE QUADRANT
AND WITHIN 130 NAUTICAL MILES IN SE QUADRANT
AND WITHIN 70 NAUTICAL MILES IN SW QUADRANT
AND WITHIN 120 NAUTICAL MILES IN NW QUADRANT.

DEEP CONVECTION REMAINS PERSISTENT WITH PRIMARY BANDS TRYING TO WRAP
AROUND LLCC. OVERALL ORGANISATION HAS IMPROVED SIGNIFICANTLY IN THE
PAST 24 HOURS. CYCLONIC CIRCULATIONS EXTENDS UP TO 500HPA WITH GOOD
OUTFLOW TO THE SOUTH. SYSTEM LIES JUST SOUTH OF AN UPPER RIDGE IN A
LOW TO MODERATE SHEARED ENVIRONMENT. SST AROUND 29 DEGREES CELSIUS.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

An active area of responsibility :smile:
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

Cyclone Tracy wrote: Sat 24/03/2018 22:41 An active area of responsibility :smile:
Albeit briefly… ;)

Iris went downhill soon after Nadi named her, and was declared an Ex-TC by the BoM early this morning about 17 hrs later. Her LLCC remained mostly exposed with convection sheared to the east during that time. JTWC never acknowledged her TC status with their estimated 1-minute mean winds only reaching around 25-30 knots.

TC Iris - BoM track-map - Mar 24, 1359z.png

Marcus also became an Ex-TC last night, about 8.5 days after being named.

TC Marcus - BoM Track-map - Mar 24, 1221.png

And TC Nora made landfall as a Cat 3 a few hours ago north of Pormpuraaw.

TC Nora - BoM track-map - Mar 24, 1636z.png
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

UK teaches EC and GFS another lesson on tropical cyclone steering with TC Nora. Completely nailed the crossing 48 hours out where the others took her much further south. Cyclone chasers ignored UK and Access R and paid the price. BoM's and JTWC track maps were 2nd rate because they also eliminated the UK as an outlier. BoM's map on advice 10 on Friday is a good example. UK also nailed Hola 2 weeks ago with the easterly steer off the upper NI and was the outlier.

UK at the moment is a clear leader with tropical cyclone modelling IMO.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

Seems there's life in Iris yet!, with good flaring convection to the north this morning wrapping into the LLCC. Based on 1-minute mean winds, JTWC are now calling Iris a TC with some strengthening expected…
WTPS32 PGTW 242100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 17P (IRIS) WARNING NR 001//
REF/A/MSG/JOINT TYPHOON WRNCEN PEARL HARBOR HI/
240121ZMAR2018//
RMKS/
1. TROPICAL CYCLONE 17P (IRIS) WARNING NR 001
---
WARNING POSITION:
241800Z --- NEAR 14.7S 158.9E
MOVEMENT PAST SIX HOURS - 240 DEGREES AT 06 KTS
POSITION ACCURATE TO WITHIN 030 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

Tropical storm IRIS is currently a borderline cyclone and will be a depression probably in the next 48 hours. Then it gets interesting :smile: There is a massive difference in opinion amongst all the big models but UKMet run 2503 12Z has her riding the ridge back into very favourable wind shear and a simmering 28 to 29 SST in the coral sea in the longer term.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

Our phantom TC is now also ex-TS Iris, with JTWC's 1-minute mean winds not getting above 35 kt.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

Ex TC Iris will be annoying Nth Queensland for a while to come :smile:

Latest EC ensemble now increasing the chances of a tropical depression near Fiji over Easter and has increased the chances of it turning into a cyclone. This is another system for NZ to watch closely as the SST's around the NI are still between 21c to 22c and well above average. With stronger pulses from the polar vortex underway, it's a volatile mix if the timing lines up with an ex TD or TC drifting down IMO.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by TonyT »

Cyclone Tracy wrote: Wed 28/03/2018 10:59 Ex TC Iris will be annoying Nth Queensland for a while to come :smile:

Latest EC ensemble now increasing the chances of a tropical depression near Fiji over Easter and has increased the chances of it turning into a cyclone. This is another system for NZ to watch closely as the SST's around the NI are still between 21c to 22c and well above average. With stronger pulses from the polar vortex underway, it's a volatile mix if the timing lines up with an ex TD or TC drifting down IMO.
Plus the MJO is re-emerging into phases 7&8 which are the low pressure phases, so it might be a messy week or two ahead.
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Re: Tropical & Extra Tropical cyclone season 2017/18

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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

GEFS ensemble now how has an invest on the tropical disturbance near Fiji. This has the potential to become Tropical Cyclone Jo later in the Easter period. Most models have the sub tropical ridge protecting NZ after 120 hours but if the potential TC stalls, this would change.

Ex TC Iris has the potential to loiter around the north and central Queensland coast, maybe reforming as a TC but more likely to be a depression and trigger a significant rainfall event. One to watch in Oz.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

Tropical depression near Fiji is now pushing 34 knots. Very close to officially becoming tropical cyclone Josie soon. Longer term projections has moved an XTC Josie considerably further west towards the NI but still well offshore at this stage.

ExTC Iris, having a hot tower eruption near Willis Island off the FNQ coast currently. Conditions becoming quite favourable in 96 hours which will have North Queenslanders clearing the Supermarket shelves tomorrow I think.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

TC Josie was named by RSMC Nadi around 1am this morn NZST…

GALE WARNING 059 ISSUED FROM RSMC NADI Mar 311318 UTC.

TROPICAL CYCLONE JOSIE CENTRE 995HPA CATEGORY 1 WAS LOCATED NEAR 18.4
SOUTH 175.7 EAST AT 311200 UTC.
POSITION POOR.
REPEAT POSITION 18.4S 175.7E AT 311200 UTC.
CYCLONE MOVING EAST SOUTHEAST AT 11 KNOTS. CYCLONE INTENSIFYING.
EXPECT SUSTAINED WINDS OF 35 KNOTS CLOSE TO THE CENTRE INCREASING TO
40 KNOTS BY 010000 UTC.
...
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

TC IRIS is back from the dead off North Queensland :smile:
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

TC Iris has just been upgraded at Cat 2 and expected to make Cat 3 overnight…
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Cyclone Tracy »

TC IRIS is certainly an intriguing little beast. It's currently moving into very favourable shear with 28c SST, she could really take off if she steers near the Whitsunday islands. The BoM and JTWC are really playing pin the tail on the donkey with this one.

TC Josie keeping out of everyone ways and on its way to the XTC graveyard in the next few days east of NZ. Ridge doing a good job protecting NZ currently.


EC ensemble has another Tropical disturbance on the cards around Vanuatu this weekend and chances of another cyclone have risen for mid next week. With a strong upper low heading into NZ next week, the synoptics will be worth keeping a close eye on. An XTC with a polar injection and warm SST's is an atomic mix if it lines up.
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

RSMC Nadi had Josie as an extratropical cyclone at around 7am this morning NZST…
TROPICAL DISTURBANCE ADVISORY NUMBER A11 ISSUED FROM RSMC NADI
Apr 021915 UTC.

EX-TROPICAL CYCLONE JOSIE CENTRE 996HPA WAS LOCATED NEAR 21.7S 178.7E
AT 021800 UTC. POSITION FAIR BASED ON HIMAWARI-8 EIR AND PERIPHERAL
SURFACE REPORTS. CYCLONE MOVING SOUTH SOUTHEAST AT ABOUT 4 KNOTS.
MAXIMUM 10-MINUTE AVERAGE WINDS NEAR THE CENTRE ESTIMATED AT ABOUT 30
KNOTS.

LLCC EXPOSED WITH DEEP CONVECTION DISPLACED TO THE FAR EAST. SYSTEM
LIES JUST EAST OF AN UPPER SHORTWAVE TROUGH WITH MODERATE TO STRONG
UPPER DIVERGENCE TO THE SOUTHEAST AND IN A HIGH SHEARED ENVIRONMENT.
OUTFLOW GOOD TO THE EAST. SST AROUND 27 DEGREES CELCIUS.
...
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Re: Tropical & Extra Tropical cyclone season 2017/18

Unread post by Nev »

Cat 2 Iris has struggled overnight with conditions becoming less favourable…
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