Was very busy at work today and didn't get too much chance to take a look. Good to wait for the first vis sat image anyway, and, looking at the 1km zoom from an hour ago, Chanchu's organization has improved considerably from this morning. And there continues to be good radial outflow on the west but what appears to be some shear on the NE. With the convection in the center, the eyewall is prominent again but the eye continues to be covered with a thin cirrus shield. I think the winds this morning were stronger than I realized at the time, looking at the lopsided convection in the CDO. Even though CIMSS AODT rates the winds at 90 kts, the current range of 105-110 kts in the JTWC forecast seems believeable looking at the visual and IR. Microwave passes throughout the day have mostly missed.
The core has become much smaller and IR shows that intense convection has almost completely wrapped around the core again. There is quite a bit of convection in the spiral bands outside the core as opposed to yesterday's Cat 4 structure. With the spiral bands the typhoon pretty much takes up the entire basin. JTWC warning #9 has expanded the windfields at landfall accordingly.
The last six hours the upper level winds assoc with the typhoon have curved a dent into the jet to the north, an outflow channel. I think this would be another indication of a strong storm.
The storm is at about 17N. Maybe because it is moving and the SSTs are still good enough to maintain strength, perhaps upwelling was the culprit earlier. Which makes the intensity forecast interesting. JTWC now has it steadily weakening, but if it continues moving at this rate, then SSTs are good almost to the shoreline, I think. So it may be able to maintain 100-110 kts until close to landfall. Heat content falls off drastically north of 17-18N, so either it made a recovery because it hit a spot with some reasonably deep heat content this afternoon, and intensity will slide down again once it moves further north, past this area, or, SSTs at this current speed are enough to maintain the current intensity, without significant heat content.
The model plots have converged and this is the tightest they have ever been so there is good confidence in the track.
* * * * * *
9:30pm update -- Warning #30 is out. The track has been shifted very slightly a little east...essentially in the noise. The initial sustained winds are raised from 110kt to 115kt (reflecting the improved sat signature). Landfall is shown at 80kts which is just shy of Cat 2 intensity, with ET beginning at that time.
Finally a microwave pass did catch part of the center and it's pretty interesting -- I'll attach it (someone please PM me how to add an image into a post!).
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Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp
Edited by Margie (Tue May 16 2006 02:44 AM)
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