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Somerset Squall

Severe Tropical Cyclone Narelle

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Tropical Cyclone 08S has formed, 700 miles north-northeast of Learmonth, Australia, and a few hundred miles north-northwest of Broome. 08S has some deep, persistant convection over the LLC which has prompted JTWC to upgrade to a 35kt TC. The cyclone should soon get a name from BOM.

The environment ahead looks conducive to allow 08S to become a potent cyclone over the next few days. In fact, JTWC are forecasting 08S to reach an intensity of 125kts in around 4 days time, which is very aggressive for a first forecast. BOM are also very bullish in their intensity forecast too.

08S is forecast to move southwestwards over the next few days along the northwestern periphery of a ridge to the southeast, over mainland Australia. A turn to the south is expected as the ridge weakens in response to a trough. However, the timing of this turn, if it even occurs, is highly uncertain, but extremely important to the coast of NW Australia. The later the turn, the more of the coast is spared from a potentially very damaging storm.

Current JTWC track (subject to change due to wide model spread in the 3-5 day time period):

sh0813.gif

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The cyclone got named Narelle overnight. Narelle is strengthening nicely, and now has sutained winds of 45kts according to JTWC, and 55kts according to BOM. Narelle has an impressive central dense overcast which continues to expand. With low shear, excellent outflow and warm sea temps expected to persist, Narelle should strengthen quickly over the coming days. JTWC now plumping for a peak of 130kts, so it looks like Narelle is going to become a monster. Current track forecast has changed little, and areas west of Karratha are most at risk from impact currently. The future track of Narelle is far from nailed on however.

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Narelle has continued to strengthen overnight and has been upgraded to a Severe Tropical Cyclone by BOM. Sustained winds are now at 65kts. Narelle maintains a solid central dense overcast with a developing eye. Further quick intensification is expected in the favourable environment.

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Narelle has strengthened to 90kts, making it a cat 2 on the SS scale. Narelle retains a solid central dense overcast flanked by banding. Further intensification is expected as Narelle heads southwest to south-southwestwards over the next few days. Communities west of Onslow, including Exmouth and Learmonth, need to prepare for damaging winds and heavy rains. If the current track verifies then it looks like Narelle could drench much of Western Australia.

sh0813.gif

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Unfortunate projected track...we need her moving inland to cool down the interior which looks like it is going to pop, such is the intensity and expansiveness of the heat this summer!

Question to you actually. Do you know the latest point in a season in which the first cyclone crossed the Australian coast? Or have there been seasons in which there were no crossings?

Thanks!

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Not sure offhand Styx, can look into it when I have more time.

Narelle is strengthening still. Winds are up to 110kts, high end cat 3 on the SS scale. Narelle has about another 18hrs to strengthen before shear begins to rise and sea temps cool on the forecast track. The eye is clearing out and becoming much better defined; I think Narelle may peak at 120-130kts before she's done.

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IDE00135201301112230.jpg

High cloud is streaming from Narelle for many hundreds of miles into the south east of the country. Keeping this part of the country a little bit cooler than it may otherwise be.

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115kts ended up being Narelle's peak. The cyclone has been steadily weakening through today, and winds are down to 90kts. The eye is being eroded by shear and is losing definition. Cooling along track sea temps are reducing the depth of convection around the eye also. Conditions will only get worse as Narelle slips south over the coming days, so quicker weakening may occur over the next day or two.

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Narelle almost reached Perth but not quite. High shear and cold sea temperatures have caused Narelle to dissipate just prior to landfall in SW Australia.

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Ex Narelle is now simply a disjointed cloud mass of tropical origion to the west of Tasmania. Her last hurrah will be to bring patchy light rain to this area of the world tomorrow, before bowing out forever, consumed to the point of unrecognisable non existence by the cold Southern Ocean.

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