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Aussie (& S-Hemisphere) Cyclone Action 2010-2011


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Port Vila has south winds, 38kts/g48kts

METAR NVVV 210100Z 18038KT48KT 9999 -SHRA FEW015 SCT018 BKN040 OVC100 27/25 Q0993 RMK NIL TEMPO 210100/210400 1000 TSRA SCT002 BKN010 SCT020CB OVC0040

20110220.2224.metopa.x.89_1deg.17PATU.115kts-937mb-175S-1696E.74pc.jpg

Looks like there are a few personal weather stations that we'll get to monitor as it creeps down the island chain

post-22-0-45810500-1298254794.png

Setting aside the ERC issue, it looks nice from a broader perspective.

210000.JPG

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Carlos is moving along the Western Australia coast, and the latest BoM forecast has it crossing the North West Cape near Exmouth within 48 hrs just below Cat-3 (AUS) strength, with winds of 60 kt (10-min). A Cyclone Warning is up for the entire Pilbara and N Gascoyne coasts.

The satellite presentation isn't exactly anything to write home about-- with convection a bit sheared to the W.

One point to note-- form the BoM's Technical Bulletin:

Carlos presents a significant storm surge threat especially as tides are close to HAT in this region during the next few days. The shelf wave is likely to cause tides to rise above the high water mark regardless of whether the cyclone directly causes a storm surge on the coast.

The Pilbara coast will be on the left (stronger) side of the circulation as the cyclone scrapes the coast, with onshore flow following the passage of the center.

post-19-0-03450000-1298276597.gif

post-19-0-75269300-1298276605.jpg

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Interesting. Do you feel like it looks like a near-'cane? Like, are you surprised by the SATCON value or surprised because the cyclone looks better than you expected?

No, it doesn't look like a near-cane to me, but I trust SATCON more than I trust my eyes. That said, it does have a pretty sweet curved band coming out of the center.

20110221.0912.f15.x.85h_1deg.15SCARLOS.45kts-989mb-189S-1193E.76pc.jpg

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No, it doesn't look like a near-cane to me, but I trust SATCON more than I trust my eyes. That said, it does have a pretty sweet curved band coming out of the center.

Cool-- well, maybe it's getting its act together. I just looked at the latest IR shots and I'm not too impressed. Tell me, what does SATCON measure, exactly?

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SATCON is the weighted average between the CIMSS AMSU, CIMSS ADT, and CIRA AMSU intensity techniques. The weights were determined empirically to minimize error of the in-sample variance compared to recon observations. There was a talk in Tuscon that showed that SATCON has lower error scores than any of the three platforms alone as well as manual Dvorak in the Atlantic and East Pacific for an out of sample set.

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SATCON is the weighted average between the CIMSS AMSU, CIMSS ADT, and CIRA AMSU intensity techniques. The weights were determined empirically to minimize error of the in-sample variance compared to recon observations. There was a talk in Tuscon that showed that SATCON has lower error scores than any of the three platforms alone as well as manual Dvorak in the Atlantic and East Pacific for an out of sample set.

Cool, thanks-- definitely good to know this.

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Very weak, but very important. Why the blank on the 6-10 day?

Also an explanation re how to read this may be in order for some of us (especially me.... the mjo has always flummoxed me... I know it's about rainfall but its interaction with el nino throws things a little))

The GEFS just dropped the anomalies in the 6-10d. Not sure why. The map from yesterday showed subsidence over Australia in the 6-10 day period. Here is the Hovmoller the evolution of the anomalies.

tlon_olr_full.gif

The GEFS isn't the best model to use for the MJO, but it's the one with most products available. AFAIK, the Euro MJO PS progs are the only ones produced, but it's the only model that has shown skill in predicting the MJO in the medium range.

To your general question about the MJO, I could fill a 20 page document about it. Here is a general explanation and you can ask more questions about it from there.

The MJO is an eastward propagating wave with a period of ~30-60d (up to 20-90d). The wave is characterized by convergence (divergence) at the surface and divergence (convergence) aloft during the upward (downward) phases of the wave. We're not really sure what causes the MJO as it's not predicted by any of the known equations that govern the atmosphere, though solar influences are suspected.

Since convergence and divergence are difficult to assess in the atmosphere, we generally look at things like OLR anomalies and 200mb velocity potential to diagnose the MJO. Wheeler and Hendon (2004) performed a principal component analysis on those parameters and others to develop the MJO phase space in an attempt to explain the most variance associated with different modes of the MJO. Below, you'll find a map with OLR projections for each phase of the MJO for the current period of time.

mjo_olr_comps.gif

Here is an explanation from the BOM that covers many of the basics in an Australia-centric view.

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Carlos really looks like he wants to visit Port Hedland.

http://www.bom.gov.a...loop.shtml#skip

Yeah, there does seem to be a bit of a SW wobble. It seems increasingly likely that it'll cross somewhere on the Pilbara or Gascoyne coasts.

Latest radar still shows a well-defined (though broad) center and distinct banding, although the core convection is still quite asymmetric:

post-19-0-15700300-1298303789.gif

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OBs for Bedout Island... close to the wall... he's barely puffing. If Carlos manages to skirt the coast and intensify then after Darwin he is certainly one to remember.

http://www.bom.gov.au/products/IDW60801/IDW60801.94310.shtml

Thanks for linking us to this. The obs don't knock my socks off, but they're not bad, either; the island has had solid gales for several hours.

Highest values so far: sustained 45 kt (10-min), gust to 55 kt.

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Thanks for linking us to this. The obs don't knock my socks off, but they're not bad, either; the island has had solid gales for several hours.

Highest values so far: sustained 45 kt (10-min), gust to 55 kt.

sustained 45 is pretty good for a storm like carlos

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sustained 45 is pretty good for a storm like carlos

Agreed. Not only that, the winds have been consistently around that speed for a few hours. I guess the island is quite exposed, so it gets near-marine-exposure winds.

Pressure drop, direction change and some starting to get serious gusts at Bedout

Yep. Highest winds yet have just occurred: 46 kt gusting to 57.

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Carlos is hitting Hurricane status.

http://www.bom.gov.au/products/IDW60801/IDW60801.94310.shtml

Still reckon he will cross. Bedout is only about 100km roughly north of Port Hedland.

Winds are now coming from the north.

Well, for a cyclone to reach official hurricane status, it must produce a sustained wind of 64 kt-- not just a gust. :D

But, yes, it's now producing hurricane-force gusts.

Highest winds yet: 47 kt gusting to 65, out of the N. The pressure has held steady at around 986 mb for an hour now, so I'll bet it's bottomed out.

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One thing these readings show: the cyclone is a tad stronger than the BoM estimated in their last Technical Bulletin, in which they indicated 988 mb/45 kt (10-min). This station has already exceeded both values-- only by a small margin, granted-- but one also has to assume that it did not sample the absolute lowest pressure or highest winds.

That Technical Bulletin was from 12Z, so I don't think the BoM was necessarily off. Rather, the cyclone may have strengthened since then.

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Port Hedland OBs

http://www.bom.gov.au/products/IDW60801/IDW60801.94312.shtml

This TC continues to amaze.

. BOM has chosen the JTWC model and while that was scarily unerring for Yasi (and trust me that was the scariest few days of my life when I thought a Cat 5 was heading directly at me, and I have seen a few, but it is particularly enlightening when you have a wooden home on a mountainside facing the Coral Sea) I still think the track is wrong and radar is bearing this out..

Wow-- yeah. Port Hedland is already having 35 kt (10-min), gusting to 52-- an official gale. Nice!

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