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Cyclone Yasi


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Cyclones around Australia generally move very unpredictably. However, with this one, the steering pattern seems very strong and well-established-- therefore, you'll find that the BoM, the JTWC, and most of the computer models are in solid agreement Re: the track. Of course, it can always change-- you just never know with these things-- but with this one the confidence in the track forecast is much higher than average.

Given this, you should plan for a direct hit.

OK - I have just decided that I am going to stick to watching storm chasers on TV....man you guys are brave....I have been whinging for a cyclone for years - I thought it would be so exciting however now my first cylone and I get this cracker!

Anyway what can ya do? You just have to be prepared and make the most of it......may as well try and make the most of this experience (I say with a very nervous voice).....

Thanks for all of your help Josh......

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OK - I have just decided that I am going to stick to watching storm chasers on TV....man you guys are brave....I have been whinging for a cyclone for years - I thought it would be so exciting however now my first cylone and I get this cracker!

Anyway what can ya do? You just have to be prepared and make the most of it......may as well try and make the most of this experience (I say with a very nervous voice).....

Thanks for all of your help Josh......

You're very welcome, Mardi. :)

It'll be a big, scary cyclone-- and I'd trade places with you in a second if I could. In fact, I'm d*mn jealous. :lol: The scariness is part of what makes it so thrilling. I honestly think deep down that's what most chasers want-- to be frightened by what they chase. I've gotten a little freaked out on a couple of my chases, and those are my favorite memories. A chaser friend of mine who goes after tornadoes-- MEkster (a moderator in this forum)-- and I agreed that a good chase is a scary chase. I know, it sounds odd.

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You're very welcome, Mardi. :)

It'll be a big, scary cyclone-- and I'd trade places with you in a second if I could. In fact, I'm d*mn jealous. :lol: The scariness is part of what makes it so thrilling. I honestly think deep down that's what most chasers want-- to be frightened by what they chase. I've gotten a little freaked out on a couple of my chases, and those are my favorite memories. A chaser friend of mine who goes after tornadoes-- MEkster (a moderator in this forum)-- and I agreed that a good chase is a scary chase. I know, it sounds odd.

lol.....crazy....anyway I will let you know how I go.......think of me this time tomorrow....lets hope I still have a roof on Thursday night....

Cheers

Mardi

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Nice, indeed. JTWC went to 120 kts at 12z and the BOM is up to 100 kts (10-min). The AMSU pass from 1130z looks like there are two mesovortices on the NW and SE sides of the eyewall. Still not enough resolution to say for sure whether it is going through RI or not, but I'd expect the intensification trend to continue.

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Nice, indeed. JTWC went to 120 kts at 12z and the BOM is up to 100 kts (10-min). The AMSU pass from 1130z looks like there are two mesovortices on the NW and SE sides of the eyewall. Still not enough resolution to say for sure whether it is going through RI or not, but I'd expect the intensification trend to continue.

Yeah, I just noticed those upgrades! Since the BoM's value converts to ~115 kt (1-min), both agencies are now calling it a Cat 4 USA. Serious stuff!

The new BoM forecast has the center at the coast, just a few mi S of Cairns, with winds of 105 kt (10-min), at 12Z tomorrow. The consistency of the BoM and JTWC forecasts has been amazing with this. The forecast landfall point hasn't budged for over a day.

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Tidbit from the BoM's Technical Bulletin, Re: the intensity:

Yasi has intensified in the last 6 hours. The environment of low shear and good upper level outflow, assisted by an upper low to the south, is conducive to maintaining current intensity. There is the possibility of some further intensification before landfall.

So, the basic vibe I'm getting is that they don't expect too much more strengthening. But, really, it's already a very intense storm-- it would have tremendous and devastating impact at its current intensity.

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Tidbit from the BoM's Technical Bulletin, Re: the intensity:

Yasi has intensified in the last 6 hours. The environment of low shear and good upper level outflow, assisted by an upper low to the south, is conducive to maintaining current intensity. There is the possibility of some further intensification before landfall.

So, the basic vibe I'm getting is that they don't expect too much more strengthening. But, really, it's already a very intense storm-- it would have tremendous and devastating impact at its current intensity.

Yeah, I agree with the BoM for the most part. If the donut never forms, there's not a whole lot of room left for inefficient intensification.

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Yeah, I agree with the BoM for the most part. If the donut never forms, there's not a whole lot of room left for inefficient intensification.

The eye has been gradually clearing out all morning (er, night over there), with the latest frame looking the best so far. It's also taking a long time for the coldest cloud tops to wrap all the way around, but I think it's under way. I would give her a bit more time.

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The eye has been gradually clearing out all morning (er, night over there), with the latest frame looking the best so far. It's also taking a long time for the coldest cloud tops to wrap all the way around, but I think it's under way. I would give her a bit more time.

Between you and me, I brought it up to 130 kts this morning to my clients (when it was still 100 kts) ;)

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The most ominous forecast I've seen from the JTWC. They have the cyclone coming ashore just S of Cairns in ~24 hrs with winds at a whopping 130 kt! Note the forecast agrees perfectly with the BoM:

post-19-0-20357200-1296574282.gif

TROPICAL CYCLONE (TC) 11P (YASI), LOCATED APPROXIMATELY 450 NM EAST-NORTHEAST OF CAIRNS, AUSTRALIA, HAS TRACKED WEST-SOUTHWESTWARD AT 17 KNOTS OVER THE PAST SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY SHOWS A 10 NM EYE, FROM WHICH THE INITIAL POSITION WAS BASED. THE INITIAL INTENSITY WAS BASED ON PGTW AND ABRF DVORAK ESTIMATES RANGING FROM 115 TO 127 KNOTS. A POLEWARD OUTFLOW CHANNEL INTO AN UPPER LEVEL LOW TO THE SOUTH, ALONG WITH GOOD EQUATORWARD OUTFLOW HAS ALLOWED FOR RAPID INTENSIFICATION WITHIN THE PAST 12 HOURS. TC 11P IS CURRENTLY TRACKING ALONG THE NORTHERN PERIPHERY OF A DEEP LAYER SUBTROPICAL STEERING RIDGE AND IS EXPECTED TO TRACK GENERALLY WEST-SOUTHWESTWARD THROUGHOUT THE FORECAST PERIOD. THE SYSTEM SHOULD CONTINUE TO INTENSIFY DUE TO EXCELLENT OUTFLOW, LOW VERTICAL WIND SHEAR, AND FAVORABLE OCEANIC CONDITIONS. AROUND TAU 24, THE SYSTEM IS FORECAST TO MAKE LANDFALL JUST SOUTH OF CAIRNS AND BEGIN WEAKENING AS IT TRACKS INLAND. THE AVAILABLE NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT AND TRACK CONFIDENCE IS HIGH.

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I guess if there is good news Cairns might be on the north side, hence the good side since the surge would come in south of the storm.

It will actually make a big difference. The cyclone will be coming ashore really fast, so winds S of the center will be way stronger. Cairns shouldn't get worse than Cat-2 or maybe Cat-3 winds if it's on the N side-- still very, very severe, but not the craziness that will happen just left of the center.

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It will actually make a big difference. The cyclone will be coming ashore really fast, so winds S of the center will be way stronger. Cairns shouldn't get worse than Cat-2 or maybe Cat-3 winds if it's on the N side-- still very, very severe, but not the craziness that will happen just left of the center.

A little tick south and Innisfail is Larry'ed again.

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This is one of those times where the ADT performs very well (cleared out eye vs. CDO or sheared patterns). That said, it missed the center on its last pass (time sensitive - 1122 EST/1622z).

11P.GIF

Even missing the center, the raw number is 6.7. I bet this is real close to Cat 5.

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The latest BoM advice has the cyclone even stronger-- flirting with their Cat 5!

The 11 pm advice had the intensity at 940 mb, with max gusts to 260 km/hr.

The new, 2 am advice has 935 mb/gusts to 270 km/hr.

Their Cat 5 starts when max gusts hit 280 km/hr (151 kt).

Josh, their cat 5 is based on gusts, not sustained winds? I know their criteria for sustained winds is different-- perhaps that's the reason why. I believe they take a 10 min avg for sustained winds.

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This is one of those times where the ADT performs very well (cleared out eye vs. CDO or sheared patterns). That said, it missed the center on its last pass (time sensitive - 1122 EST/1622z).

Even missing the center, the raw number is 6.7. I bet this is real close to Cat 5.

Wow. You think?

Josh, their cat 5 is based on gusts, not sustained winds? I know their criteria for sustained winds is different-- perhaps that's the reason why. I believe they take a 10 min avg for sustained winds.

Yep-- they assign category based on max gusts.

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If it's 6.7 and missing the warmest part of the eye in its calculation, doesn't 6.9-7.0 seem plausible? I'm not much of a Dvorak expert so I'm just extrapolating.

I do think that it's a strong 4, but the eye just doesn't look cleared out enough to meet my subjective cat 5 test.

We need recon.

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