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Somerset Squall

Severe Tropical Cyclone Zelia

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Invest 94P has become Tropical Cyclone Zelia, with intensity at 35kts. The system is located east of Queensland but should move away from the Australian mainland and roughly follow Vania out of the tropics.

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Australia's third-largest city started cleaning up stinking mud and debris yesterday after some of the worst floods on record, but forecasters have now warned a cyclone could hit.

A cyclone forming in the Coral Sea, which had threatened the coast, had begun moving north into the Pacific, said state premier Anna Bligh. 'We'll keep watching it, but maybe our luck is about to change,' she said.

http://www.dailymail.co.uk/news/article-1347046/Australia-floods-Clean-begins-threat-cyclones.html#ixzz1AzyAFjvA

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Zelia is a small cyclone in a very favourable environment, and has strengthened rapidly since this morning. Intensity has risen to 55kts as Zelia moves southeastwards over hot water (30-32C), low shear and excellent outflow. The forecasting of cyclones as small as Zelia is very difficult, and I think JTWC's peak of 80kts is a fair enough assessment given the uncertainity. However, the potential exsists for further rapid intensification and Zelia could become a lot stronger than the JTWC forecast. Thankfully, Zelia is moving southeastwards away from Queensland as Cookie's post states. New Caledonia need to keep a close eye on Zelia though, as the southeasterly track will bring the strengthening cyclone uncomfortably close.

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Latest BoM track puts Norfolk Island in the firing line, again, and maintains the cyclone as a Category 3 despite it getting pretty close to 30S by that point (when it crosses 25S it becomes RSMC Wellington's responsibility, and prior to that when it crosses 160E it becomes RSMC Nadi's responsibility, so it looks like this TC will be held by 3 offices during its life.)

The interaction with ex-TC Vania will be interesting, and the combined system, whatever structure it resembles, will reach NZ on Tuesday.

IDQ65001.gif?1295074814939

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Here is the JTWC track of Zelia.

post-7526-0-19373600-1295080792_thumb.jp

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Zelia remained a 55kt tropical cyclone for a day but has now resumed strengthening, and could be about to begin a burst of rapid intensification. Intensity has increased to 65kts, and Zelia is now categorised a severe tropical cyclone by BOM. Severe Tropical Cyclone Zelia has developed a small eye embedded in the CDO feature. This eye could be the precursor to a big rise in intensity, but as I mentioned before, it's difficult to predict with cyclones as small as Zelia. Conditions will remain favourable for a good 48hrs yet, so Zelia should intensify a little more at the least. Track forecast is largely the same as J07 describes. If Zelia remains small it may pass New Caledonia will little effect.

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Indeed Cookie, the eye is beginning to clear out nicely now and intensity has risen to 80kts. The small cyclone is really making good use of the excellent upper level conditions and hot sea surface temperatures. How high can Zelia go before cooler waters and increasing shear make mince meat out of the storm beyond 36hrs?

Latest image of Zelia:

coralseavislatest.jpg

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Brisbane's final track map for Zelia.

The next issue will be done by RSMC Nadi. It looks like they will get it for about 12 hours and then it will pass to RSMC Wellington.

Brisbane have it becoming a tropical low shortly after crossing 30S.

So on the whole it's been a pretty consistent forecast for this system.

Details:

Time (EST)Intensity CategoryLatitude

(decimal deg.)Longitude

(decimal deg.)Estimated Position

Accuracy (km)0hr4 pm January 16319.0S158.7E35+6hr10 pm January 16320.9S160.4E95+12hr4 am January 17322.8S162.1E130+18hr10 am January 17325.0S163.8E155+24hr4 pm January 17327.3S165.5E185+36hr4 am January 18tropical low32.3S168.6E230+48hr4 pm January 18tropical low38.3S171.4E285

IDQ65001.gif?1295161277480

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Zelia has become a cat 2 on the SS scale with intensity rising to 90kts. The tiny cyclone is racing southeastwards at a speed of 24kts now, more than double the average speed for a tropical cyclone's movement. This will put Zelia over colder water in about 12hrs time. Tiny Zelia will then begin extratropical transition as it continues to race towards New Zealand.

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HURRICANE WARNING 042 ISSUED FROM RSMC NADI Jan 17/0103 UTC 2011 UTC.TROPICAL CYCLONE ZELIA CENTRE 970HPA CATEGORY 3 WAS LOCATED NEAR 24.9 SOUTH165.0 EAST AT 170000 UTC.POSITION FAIR.

REPEAT POSITION 24.9S 165.0E AT 170000 UTC.

CYCLONE MOVING SOUTHEAST AT 30 KNOTS. EXPECT SUSTAINED WINDS OF 80 KNOTS CLOSE TO THE CENTRE.

EXPECT WINDS OVER 63 KNOTS WITHIN 25 NAUTICAL MILES OF CENTRE,

OVER 47 KNOTS WITHIN 40 NAUTICAL MILES OF CENTRE AND

OVER 33 KNOTS WITHIN 180 NAUTICAL MILES OF CENTRE IN THE NORTHERN SEMICIRCLE,

WITHIN 120 NAUTICAL MILES OF THE CENTRE IN THE SOUTHEAST QUADRANTAND

WITHIN 60 NAUTICAL MILES OF THE CENTRE IN THE SOUTHWEST QUADRANT.

FORECAST POSITION NEAR 29.2S 168.3E AT 171200 UTC AND NEAR 33.8S 171.3E AT 180000 UTC.

ALL VESSELS WITHIN 300 NAUTICAL MILES OF CENTRE ARE REQUESTED TO SEND REPORTSEVERY THREE HOURS TO TCWC WELLINGTON. VOS REPORTING SHIPS USE NORMAL CHANNELS. THIS WARNING CANCELS AND REPLACES WARNING 041. PRIMARY RESPONSIBILITIES FOR FUTURE WARNINGS ON TROPICAL CYCLONE ZELIA WILL RESTWITH TCWC WELLINGTON.

65643.gif?1295233218953

And here is the forecast for Australia's Norfolk Island:

Norfolk Island Forecast

IDN10008Australian Government Bureau of Meteorology New South Wales Norfolk Island Forecast Issued at 3:00 pm EDT Monday on 17 January 2011 Warning Summary at issue timeTropical Cyclone Warning for Severe Tropical Cyclone ZELIA issued by New ZealandMet Service at 12:55 NFT.

Hurricane Warning for Ocean Waters Weather SituationA CYCLONE WARNING IS IN FORCE FOR NORFOLK ISLAND

At 11:30 NFT, Severe Tropical Cyclone Zelia, was located near 24.9S 165.0E about550 km (300 nm) to the northwest of the island and moving southeastwards atabout 45 km/hr (25 knots). Its forecast track has it passing close to NorfolkIsland this evening as a Category 2 or 3 system, which would produce destructiveto very destructive winds, torrential rain and high to phenomenal seas at theIsland. There is a chance Tropical Cyclone Zelia will pass northeast of theisland rather than southwest as previously forecast.Please refer to the current Tropical Cyclone Advice for Norfolk Island for moredetails, issued by the New Zealand Met Service at 1255 NFT and due to be revisedaround 1900 NFT on 17 January 2011.

Forecast for the rest of Monday: Windy. Cloudy periods. Showers developing this afternoon, increasing to rain andbecoming heavy, with torrential downpours expected this evening and overnight.NE winds 30/40 km/h (15/20 knots), increasing to damaging gale force thisevening, with average speeds of 75km/h (40 knots) gusting 110km/h (60 knots).The winds should then rapidly rise to destructive storm force during the eveningand overnight, average speed 95km/h (50 knots) gusting 150km/h (80 knots), andpossibly as high as very destructive hurricane force, average speed 120km/h (65knots) gusting to 185km/h (100 knots) close to midnight.Combined seas rising to high to phenomenal during the evening and overnight.

Forecast for Tuesday: Windy. Rain, heavy at times at first with possible torrential downpours. Easingby the afternoon. N/NW'ly winds 95km/h (50 knots) gusting 150km/h (80 knots)early, but possibly reaching 120km/h (65 knots) gusting to 185km/h (100 knots).W/NW winds gradually decreasing below gale force during the morning andcontinuing to ease through the day. W/SW'ly 20/40 km/h (10/20 knots) by theevening.

High to phenomenal seas moderating during the morning. Heavy NE/NW swellmoderating.

Precis: Cyclonic conditions easing. Min: 22 Max: 26

post-7526-0-86292400-1295236594_thumb.gi

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First Wellington forecasts and warnings. It's bad practice to re-classify overnight, so more likely is that 17/18Z (i.e. 6AM tomorrow morning) will be when it officially becomes ex-tropical.

High Seas Forecast: Subtropic

Issued by MetService at 8:32pm 17 January 2011

Forecast: Poor visibility in rain within 120 nautical miles of First Low 1007hPa near 29S 173W moving westsouthwest 5kt. Poor visibility in rain within 180 nautical miles of Second Low 975hPa, Tropical Cyclone Zelia,near 27S 167E moving southeast 30kt. Poor visibility in rain within 120 nautical miles of First Trough 31S 167E 35S 168E 37S 164E moving eastsoutheast 25kt, to Third Low 993hPa near 33S 164E moving southeast 10kt and filling after 180000Z. Throughout much of area east of second and third lows, to 170W: Northerly quarter 25kt at times,tending clockwise about first,second and third lows, with storms and gales as in warnings 318, 320 and 321, and areas of heavy swell in gale areas.Second Trough 34S 151E 36S 154E 40S 158E moving east 35kt.Southwest of second trough:Southwest 25kt.

TCSTORM WARNING 321

This affects ocean area(s): SUBTROPIC

AT 7:00pm Monday 17 January 2011

STORM WARNING 321

This affects ocean area: SUBTROPIC

Tropical Cyclone ZELIA [975hPa] centre was located near 27.5 South 167.5 East at 170600 UTC.

Position Fair.

Repeat position 27.5S 167.5E at 170600 UTC.

Cyclone is moving southeast 30 knots.

Expect sustained winds of 60 knots close to the centre easing to 45 knots by 171800 UTC.

Expect winds over 48 knots within 40 nautical miles of centre.

Expect winds over 33 knots within 120 nautical miles of centre in the sector from south through west to northwest and within 180 nautical miles of centre in the sector from northwest through northeast to south.

Forecast position near 32.7S 170.8E at 171800 UTC

and near 38.5S 173.6E at 180600 UTC.

This warning cancels and replaces warning 316.

Issued at 8:31pm Monday 17 January 2011

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TCSTORM WARNING 322This affects ocean area(s): FORTIES and SUBTROPIC

AT 1:00am Tuesday 18 January 2011

STORM WARNING 322

This affects ocean areas: SUBTROPIC and FORTIES

Tropical Cyclone ZELIA [980hPa] centre was located near 29.6 South 169.2 East at 171200 UTC.

Position Fair.

Repeat position 29.6S 169.2E at 171200 UTC.

Cyclone is moving southeast 30 knots.

Expect sustained winds of 55 knots close to the centre easing to 40 knots by 180000 UTC.

Expect winds over 48 knots within 40 nautical miles of centre.

Expect winds over 33 knots within 120 nautical miles of centre in the sector from south through west to northwest and within 180 nautical miles of centre in the sector from northwest through northeast to south.

Forecast position near 35.3S 172.0E at 180000 UTC

and near 41.3S 174.5E at 181200 UTC.

This warning cancels and replaces warning 321.

Issued at 1:56am Tuesday 18 January 2011

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Zelia is now racing towards New Zealand at a speed of 34kts. Intensity has fallen to 55kts, but Zelia is still tropical for now. Extratropical transition should be complete in 12hrs just before Zelia reaches New Zealand.

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It was re-classified this morning (18Z) as extra-tropical a few hours after you wrote that Cridders. Goodbye Zelia, you were quite interesting.

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