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Major Hurricane Irene live tracking


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Definitely intensifying according to this eyewall dropsonde:

Dropsonde Location: Dropped in eyewall 135° (SE) from the eye center.

Splash Location: 22.48N 73.91W

Splash Time: 17:17Z

Splash Location: 22.61N 73.97W viewmap.png

Splash Time: 17:17:12Z

Mean Boundary Level Wind (mean wind in the lowest 500 geopotential meters of the sounding):

- Wind Direction: 160° (from the SSE)

- Wind Speed: 116 knots (133 mph)

Average Wind Over Lowest Available 150 geopotential meters (gpm) of the sounding:

- Lowest 150m: 160 gpm - 10 gpm (525 geo. feet - 33 geo. feet)

- Wind Direction: 155° (from the SSE)

- Wind Speed: 115 knots (132 mph)

Looks like we have a Cat 4 on the way.

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You can look at the SST maps in this & other threads and the shear forecast is based on the SHIPS model, also mentioned in this thread.

I don't think Irene will stay 135+ for more than 24 hours, though. I highly doubt we see a landfalling Cat 4 (anything above 120 is far-fetched, even 110-120 is optimistic).

One thing is noteworthy though-- as it weakens, its wind field should expand even more, and we may have something akin to what Ike was-- maybe all the way up here.

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One thing is noteworthy though-- as it weakens, its wind field should expand even more, and we may have something akin to what Ike was-- maybe all the way up here.

Like I said, after the ERC, it looks like Irene is going to be massive. But it needs to happen sooner rather than later to actually get reorganized again

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Irene is not only intensifying in the core but look at how big she is getting. The last isobar limit for the storm is now almost 300 miles friom the eye. That means she is almost 600 miles across and growing. TS winds will really be moving out from the center.

Information valid as of:Wednesday, August 24, 2011 18:00 ZStorm Number:09

Level of tropical cyclone development:Hurricane (This information is sometimes inaccurate.)

Wind Field Details:The radius of 64 knot (74 miles per hour | 33 meters per second) winds is:

50 nautical miles (58 miles | 93 kilometers) in the northeast quadrant.

45 nautical miles (52 miles | 83 kilometers) in the southeast quadrant.

25 nautical miles (29 miles | 46 kilometers) in the southwest quadrant.

40 nautical miles (46 miles | 74 kilometers) in the northwest quadrant.

Isobar details:The last closed isobar has a pressure of 1008 mb. (29.77 inHg | 1008 hPa) The radius of the last closed isobar is 300 nautical miles (345 miles | 556 kilometers).

Radius of Max Winds:15 nautical miles (17 miles | 28 kilometers)

System Depth:Deep

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I know I have heard or read that at some point larger hurricanes start influencing weather around them and possibly track. Is there a meterological precedent for that or is it just an old wives tale?

It can happen. Check out this paper for more on the subject. http://www.atmos.ucla.edu/~fovell/fovell-corbosiero-kuo-2009.pdf

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It may be incidental but at a glance that looks like the dreaded pin-prick eye.

I wonder if we are already seeing the beginnings of the ERC taking place. The pinhole eye, which was looking rather healthy over the last hour or so, has cooled considerably in the last half hour

GOES19452011236Oh2jE7.jpg

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If you take a look at the latest visible satellite imagery, you can see the storm has become much more symmetrical over the past few hours. I wonder if this has anything to do with the storm clearing Hispaniola.

It is more likely than not a function of the westerly shear dropping off. Shear peaked this morning, with the 12z SHIPS initialized with 23kt shear , 18z initialized with 13kt of shear. Both of the last two runs of the SHIPS also shows shear dropping to single digit values by late afternoon/evening, and staying there for some time.

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It is more likely than not a function of the westerly shear dropping off. Shear peaked this morning, with the 12z SHIPS initialized with 23kt shear , 18z initialized with 13kt of shear. Both of the last two runs of the SHIPS also shows shear dropping to single digit values by late afternoon/evening, and staying there for some time.

Yep, the storm just went through some of the most significant shear it has encountered so far:

2011al09_amsuaavg_000000000000.gif

Nested dynamical models forecast a dayish lul in shear as well:

2011al09_diagplot_201108241800.png

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So I joked about it in the banter thread, but for real, Irene appears to be sporting a pinhole eye right now, and we could see central pressure take a decent tumble before the inevitable ERC

probably not. CDO temperature symmetry leaves something to be desired, and based on the increasing indications of eyewall concentricity in microwave imagery, i would suspect this is simply the collapse of the inner eyewall. CDO temps have warmed since this morning, and over the past few hours there has been little evidence of strengthening.

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Forecasting the intensity is going to be very tricky for the next 24 hours. It seems that an EWRC is looming, yet the shear has also dropped off and Irene is traveling right on the edge of 30 degree Celsius waters. Its entirely possible that Irene will waste its most favorable conditions by undergoing EWRC over the next 24 hours. I'm working on my forecast tonight, but I'm not as optimistic as yesterday for this system getting to Cat 4.

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EWRC's can be completed rapidly, or lag on for the better part of a day....The key IMO, is to have it occur before the wind field expands too much, and before we get to a latitude where this wouldn't contract again. Enduring an ERC at too high of a latitude usually means 50 mile wide eyes...from past events.

Yeah, because you're adding a stronger Coriolis force pointing radially outward.

Irene is in a good spot / time for the ERC to happen, but it needs to happen fairly efficiently within the next 24 hours.

The inner eyewall appears to be pretty unstable. The main problem right now is that the outer eyewall isn't even close to well formed yet

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Yeah, because you're adding a stronger Coriolis force pointing radially outward.

Irene is in a good spot / time for the ERC to happen, but it needs to happen fairly efficiently within the next 24 hours.

The inner eyewall appears to be pretty unstable. The main problem right now is that the outer eyewall isn't even close to well formed yet

EWRC's can occur in many ways...it's not always a complete collapse of the inner wall...very often, we can see a partial breakdown in the inner wall, and attach itself to a partially formed outer wall. The new hybrid EW (which may be a bit contorted at first) then can go on to become circular and contract, provided the overall conditions remain excellent for intensification.

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EWRC's can occur in many ways...it's not always a complete collapse of the inner wall...very often, we can see a partial breakdown in the inner wall, and attach itself to a partially formed outer wall. The new hybrid EW (which may be a bit contorted at first) then can go on to become circular and contract, provided the overall conditions remain excellent for intensification.

This is quite true - concentric eye walls (meaning double ring structure) has persisted in some very intense cyclones. Bull's Eye Bombs.

Are we really seeing an EWR here? This still looks pretty much like a system trying to get its primary eyewall up to an apex intensity; perhaps afterward we'd see that. Just speculating - from here I don't have access to microwave imagery.

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EWRC's can occur in many ways...it's not always a complete collapse of the inner wall...very often, we can see a partial breakdown in the inner wall, and attach itself to a partially formed outer wall. The new hybrid EW (which may be a bit contorted at first) then can go on to become circular and contract, provided the overall conditions remain excellent for intensification.

Maybe that'll be the case here then, because it doesn't seem like there's the classic concentric eyewall structure going on.

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New Microwave, one of the lower res, and missed the western part of the system, but recent (just half an hour old). Really would have been nice to see if the hole in the SW has filled up, but it looks like a moat region for what we can see. At the very least though, some heavy convection developed along the southern band, which was absent in the previous shot.

post-2153-0-91046800-1314220590.jpg

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This is quite true - concentric eye walls (meaning double ring structure) has persisted in some very intense cyclones. Bull's Eye Bombs.

Are we really seeing an EWR here? This still looks pretty much like a system trying to get its primary eyewall up to an apex intensity; perhaps afterward we'd see that. Just speculating - from here I don't have access to microwave imagery.

Ummm... examples? Because of the dynamics that occur in eyewalls... it is quite difficult for me to imagine a true double ring structure "persisting" (please define that also)... considering the consensus is that the inner eyewall's inflow basically gets choked by the outer eyewall.

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Ummm... examples? Because of the dynamics that occur in eyewalls... it is quite difficult for me to imagine a true double ring structure "persisting" (please define that also)... considering the consensus is that the inner eyewall's inflow basically gets choked by the outer eyewall.

My hypothesis is that double eyewall structures persist in environments where the outer eyewall is consistently disrupted by shear, dry air, etc.... these prevent the outer eyewall from intensifying and contracting, thus allowing the inner eyewall to remain intact for longer than usual.

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I think Katrina had a double eyewall that persisted for a while before landfall. Theoretically, it makes sense that that's an unstable scenario, and not likely to happen, but I don't know enough about it to really hypothesize at all.

Nice blow up in the northeast inner eyewall by the way. Major drying to the north though, and it looks like the eyewall is open to the west right now.

GOES21252011236Ca8Ssp.jpg

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