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Somerset Squall

Severe Tropical Cyclone Wilma

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TC 08P has formed from invest 95P. Intensity is 35kts. Strengthening is forecast in a favourable environment. Will have a full update later.

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08P has strengthened through the day and has been given the name Wilma, with intensity now at 45kts. Wilma has some impressive banding features and deep convection over the centre. Low shear, warm sea temperatures and good outflow should facilitate further intensification over the next day or two. Wilma is moving east-northeastwards at present along the southern side of an equatorial ridge. Ridging will become more prominant to the south of Wilma over the next day, which will induce a turn towards the southwest. Eventually, this will bring Wilma over colder water and higher shear south of 25 degrees S. Wilma should pass well east of Fiji but will move over Pago Pago over the next day or so unleashing heavy rains and potentially damaging winds here.

sh082011.11012212.gif

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A fair way east for a La Nina cyclone.

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Since I last posted until this afternoon, Wilma stopped strengthening and maintained a steady intensity in a marginal environment characterised by low shear, warm sea temps but poor outflow, especially to the west. However, this has now improved, and it looks like Wilma is intensifying again as winds have increased to 55kts and the convective pattern has become a little more symmetrical. Wilma is now heading southwards and will soon turn towards the southwest. Now the outflow is better, Wilma has the chance to strengthen. After becoming extratropical, New Zealand look to be receiving a visit from Wilma.

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Latest satellite image just out shows the possible presence of a small eye, if this is true (let's see if this feature persists) then Wilma could ramp up quite well over the next couple of days:

post-1820-0-99672300-1295895779_thumb.jp

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thanks for the updates its getting its act together nicely now

20110124.1550.f15.x.colorpct_85h_85v.08PWILMA.60kts-978mb-170S-1718W.70pc.jpg

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The eye feature has persisted (it is quite clear in Cookie's image) and intensity has risen to 65kts, making Wilma a cat 1 on the SS scale. Wilma has another 36hrs of warm water, low shear and fair to good outflow ahead of her. Therefore, further strengthening is forecast before the southwesterly to southerly track takes Wilma over colder waters and higher shear which will induce weakening.

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Wilma has strengthened further and quite quickly, with intensity now at 85kts, making Wilma a cat 2 on the SS scale. Wilma still has time to strengthen further, and I think a peak of around 100kts is easily achievable before Wilma reaches colder water. The severe cyclone is moving quite swiftly southwestwards now towards an unfavourable environment.

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Wilma has intensified a little more and winds have increased to 90kts. Wilma is maintaining a solid eye with a decent central dense overcast feature surrounding it. I think Wilma could get just a touch stronger tonight, may well peak at cat 3 on the SS scale.

post-1820-0-01335200-1295998695_thumb.jp

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Well, we can scrap cat 3! Wilma has intensified significantly overnight, with intensity rising to 115kts, making her a cat 4 on the SS scale (and cat 4 on the Australian scale). The eye has shrunk and remains well defined. Wilma still has another 12hrs of low shear and warm water to make use of, so it's possible the severe cyclone could become a little stronger before swinging south into colder water. Wilma should still be a fairly strong extratropical storm when it impacts New Zealand.

Got any good images Cookie?

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Thanks for those Cookie, Wilma has looked very impressive through today! Intensity has fallen to 105kts now, and Wilma should begin to weaken at a faster pace as waters cool significantly from now.

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nice to see the southern Hempshire active and getting some decent systems to track its been a quite few months since the Atlantic ended and nice to have something to follow in a different area of the world

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First warning on Wilma from Wellington:

HURRICANE WARNING 487

This affects ocean area: SUBTROPIC

Tropical Cyclone WILMA [930hPa] centre was located near 25.3 South 173.3 East at 270000 UTC.

Position Poor.

Repeat position 25.3S 173.3E at 270000 UTC.

Cyclone is moving southwest 10 knots but expected to be moving southsouthwest 15 knots at 271200 UTC.

Expect sustained winds of 100 knots close to the centre easing to 80 knots between 271200 UTC and 280000 UTC.

Expect winds over 63 knots within 20 nautical miles of centre.

Expect winds over 48 knots within 30 nautical miles of centre.

Expect winds over 33 knots within 200 nautical miles of centre in the southeast semicircle and within 100 nautical miles of centre in the northwest semicircle.

Forecast position near 26.2S 172.2E at 271200 UTC

and near 29.2S 171.2E at 280000 UTC.

This warning cancels and replaces warning 485.

Issued at 1:39pm Thursday 27 January 2011

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MTSAT imagery: http://www.goes.noaa.gov/sohemi/sohemiloops/shirgms.html

And latest Wellington warning:

HURRICANE WARNING 490This affects ocean area: SUBTROPIC

Tropical Cyclone WILMA [950hPa] centre was located near 26.1 South 172.9 East at 270600 UTC.

Position Good.

Repeat position 26.1S 172.9E at 270600 UTC.

Cyclone is moving southsouthwest 10 knots but expected to be moving southsoutheast 15 knots at 271800 UTC.

Expect sustained winds of 80 knots close to the centre easing to 65 knots between 271800 UTC and 280600 UTC.

Expect winds over 63 knots within 20 nautical miles of centre.

Expect winds over 48 knots within 30 nautical miles of centre.

Expect winds over 33 knots within 220 nautical miles of centre in the southeast semicircle and within 100 nautical miles of centre in the northwest semicircle.

Forecast position near 28.1S 171.6E at 271800 UTC

and near 31.3S 172.3E at 280600 UTC.

This warning cancels and replaces warning 487.

Issued at 7:55pm Thursday 27 January 2011

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Latest Wellington warning (no more Hurricane force winds near the centre):

Also attached MetService progs. The first is 1PM analysis, the next is the prognosis for 1AM this morning.

Wilma despite weakening will remain classed as a Tropical Cyclone until tomorrow morning (just over 12 hours from now), because cyclones don't get re-classified at night. Though it's possible they re-classify it at 06Z (7PM, two hours from now). We'll see.

STORM WARNING 501This affects ocean area: SUBTROPIC

Tropical Cyclone WILMA [980hPa] centre was located near 30.5 South 172.2 East at 280000 UTC.

Position Poor.

Repeat position 30.5S 172.2E at 280000 UTC.

Cyclone is moving southsoutheast 25 knots.

Expect sustained winds of 55 knots close to the centre easing to 50 knots by 281200 UTC.

Expect winds over 48 knots within 60 nautical miles of centre.

Expect winds over 33 knots within 220 nautical miles of centre in the southeast semicircle and within 100 nautical miles of centre in the northwest semicircle.

Expect winds over 33 knots within 220 nautical miles of centre in the sector from north through east to southwest and within 100 nautical miles of centre in the sector from southwest through northwest to north by 290000 UTC.

Forecast position near 34.5S 174.5E at 281200 UTC

and near 39.5S 178.8W at 290000 UTC.

This warning cancels and replaces warning 497.

Issued at 1:42pm Friday 28 January 2011

post-7526-0-53458000-1296186420_thumb.pn

post-7526-0-69987400-1296186436_thumb.pn

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nice to see the southern Hempshire active and getting some decent systems to track its been a quite few months since the Atlantic ended and nice to have something to follow in a different area of the world

Couldn't agree more. Both Wilma and Bianca have surprised me a bit and it's good to have a few intense systems to track because of their beauty on the radar!

Thanks for posting the warnings out J07, looks like New Zealand is in for a bit of a bumpy ride!

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It's over now, but was quite a beast overnight (re-classified at 7AM).

http://www.stuff.co.nz/national/4592082/Clean-up-begins-as-Cyclone-Wilma-heads-out-to-sea

Some huge rainfalls, there was an 8 hour period in the early morning where low lying Northland stations got around 200mm.

Winds were quite strong, on the back edge in the SW, the Hauraki Gulf (Auckland) had gusts of 67 knots.

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8 inches in 8 hours, that's some rainfall!

According to this http://www.stuff.co.nz/national/4598281/Wilma-blows-out-of-country some places saw 2 months of rain in 12 hours.

Compared with Bola (March `88) this was small fry though! From Wikipedia:

Cyclone Bola created some of the heaviest rainfall totals for a single storm in the history of New Zealand, with some locations receiving more than half of their annual rainfall totals from the storm. While the cyclone passed north of the island, a strong easterly flow over the North Island contained the interaction between moist air from Bola and drier air from the ridge to its southeast. In the Gisborne region, the flow resulted in the heaviest rainfall totals, when the moisture ascended over the region's western mountainous areas and condensed into precipitation. One station recorded 419 mm (16.5 in) in a 24 hour period.[6] The maximum rainfall total attributed to the storm was 917 mm (36.1 in), reported at a station near Tolaga Bay.[1] Heavy rainfall totals of up to and over 300 mm (12 in) were observed in the regions of Auckland and Northland.[6] The cyclone is the largest to be recorded in 93 years of rainfall records. As such, it had a large and lasting effect on the rivers of the area when it deposited a large amount of sediment, as recorded in the sedimentary record of Lake Tutira.[11] Shortly prior to losing its identity, the remnants of Bola also dropped 100–200 mm (4–8 in) of precipitation on the South Island of New Zealand.[]

shok.gif

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:shok: indeed! 917mm! That's a whole years worth of rain for here, and much more than I received this year (admittedly it was a dry year). Amazing stuff!

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