Recon shows double eyewall

[MClarkson]

Inbound towards the eye in the NE quad... 2 distinct 120knot max flight level readings about 30nm apart.

 

[Jeff Snyder]

Inbound towards the eye in the NE quad... 2 distinct 120knot max flight level readings about 30nm apart.

Are those MAX fl winds on the current leg? I maintain that I can't imagine that we'll see advisory at Cat 5 come 1am... Latest recon vortex I've found (0307z) suggests more like weak Cat 4 than anything.

 

[MClarkson]

they have not completed their inbound leg. Their last report was from near the inner eyewall. Next one should be out momentarily.

EDIT:

for whatever reason the transmission from the inner eyewall was missed or skipped. Have to wait for the vortex message.

in the eye D values increasing slightly... pressure probably unchanged or slightly higher.

 

[Jeff Snyder]

New special midnight CDT advisory out.... Still 160mph winds, though I don't think we've seen recon or dropsonde verification of that in the past several hours...

 

[Scott Olson]

Dvorak weakend K but is pretty much flatlined right now with not a lot of movement. I imagine the weakening trend has alot to do with the current windspeed then the barometric pressure (which easily supports strong CAT 5). And even higher barometric pressures could achieve greater windspeeds than K had early. If K can begin deepening again before landfall I'd expect a marketed increase in windspeeds perhaps back to the previous level. The depth of warm SST's is pretty impressive around LA so I still think anything is possible at this point.

 

[MClarkson]

dropsonde 910mb.

the western outbound leg saw 120knot flight level winds, and perhaps another wind max but after the western eyewall winds dropped off fast, the secondary wind max was only 85.

I dont think it has time to go through and ERC and strenghthen again. Id guess it will landfall as a 4.

 

[Jeff Snyder]

dropsonde 910mb.

the western outbound leg saw 120knot flight level winds, and perhaps another wind max but after the western eyewall winds dropped off fast, the secondary wind max was only 85.

I dont think it has time to go through and ERC and strenghthen again. Id guess it will landfall as a 4.

If that's the case, then I wonder why NHC is keeping the storm at 160mph sustained. I mean, they sounded like they weren't very confident in that assessment in the 10pm discussion, yet the recent midnight central time advisory maintained 160mph. I don't think there's been any sort of verification of any winds even near 160mph since early evening. It sounds more like Katrina is a high-end Cat 3... As I've said in other threads, 910mb is still incredibly low, but the spatial coverage of Katrina is rather large. So, spread that low perturbation over several hundred miles, and the overall pressure gradient force isn't enough for cat 5 winds. If the storm had half the size, than 910mb low would undoubtedly result in cat 5 winds, but that can't be the case now given the much-lower-the-advisory winds that recon and dropsondes are reporting.

EDIT: As soon as I say that, new VORTEX comes in at 910mb with max FL winds of 134kts. That's about 120kts at the surface, which is Cat 4 regardless.

 

[MClarkson]

469
UZNT13 KNHC 290539
XXAA 79047 99280 70893 08189 99928 25801 ///// 00/// ///// /////
92026 25400 09117 85770 21800 12145 70444 150// 14136 88999 77999
31313 09608 80424


that dropsonde just reported a 925 mb wind(basically at the surface) of 117kt, and 850 mb winds of 145 knots. Appears to be in the NE quad.

EDIT: Recon passing through the eye towards the NE quad. D values continue to rise, indicating continued pressure rise.

...although the dropsonde in the eye just came back with another 910.

 

[Anonymous]

it looks like it weakend a shitload on satellite

 

[B Doss]

Now Cat 4 @ 910mb, as expected

 

[Dave Kaplow]

The latest WV and IR satellite scans appear to show a marked deterioration in Katrina's northwestern quadrant. I'm no expert at this, but it looks to me like dryer air is getting entrained in that area, and there has been a corresponding increase in the cloud top temperatures. In short, she doesn't look as impressive as she did a couple of hours ago.

My question is: does the fact that there is an ERC in progress mean that the storm as a whole is going to be more prone to degrade in this and other ways? Because Katrina does appear to me to be coming just a bit undone, with the satellite presentation definitely losing some of its earlier symmetry.

Or is what I'm seeing in the NW quadrant a completely different aspect of the storm, unrelated to the ERC?

 

[Tim Vasquez]

Haven't looked at in detail but it appears that the storm has begun entraining the drier boundary-layer air that was sitting there on land.

Tim

 

[Philip Flory]

It appears some dry air did indeed impact the system which basically gave a look on IR of a hurricane chopped in half. HOWEVER... the core of the eye and the system itself is still quite organized...and... the last few IR scans actually show deeper convection wrapping back around the west side of the eyewall. I think the hurricane is making a last ditch effort to strengthen before landfall and should make landfall as a true CAT 4. The track is more or less looking like a devastating scenario... the turn to the N has been very poor.. the last several radar scans indicate consistent wobbles to the NNW every few scans. At any rate... landfall is going to occur likely just E of NO which makes the flood threat very significant and potentially life-altering.

Like I said... after a brief period of dry-air intrusion.. I believe the hurricane is maintaining CAT 4 strength and possibly getting re-organized if anything the next hr or two. This is no longer an "if" ... this is the real deal.

Holy smokes... was just watching CNN and the on-air met just literally yelled at the anchor to the effect of "let me talk!!!!" ... she kept interrupting him constantly. It wasn't a joke either.. he literally was pissed and told her to chill on air.... everyone is on edge I guess.

 

[MClarkson]

heights continue to rise in the eye based on recon flights... the outer eyewall is now appearing pretty solidly on radar. The weak side of the outer eyewall could extend over NO. Its about 100 nm wide.

 

[Jeff Snyder]

Looks like N.O. may have been dodged a huge bullet. Latest Recon has the hurricane at 920mb with MAX flight-level winds of only 88 kts... This is absolutely unbelievable how low the recon winds are and how rapidly the center is filling. The inner eyewall is pretty ragged on radar with very large gaps of no precipitation, particularly between the inner and outer eyewalls. Station T1 there se of New Orleans has indicated max gusts of 100mph so far.

Center of the eye appears to be about 50mi SE of New Orleans per radar imagery. We've seen time and time again that winds don't seem to be as bad as expected when the storm is weakening (and the opposite can be expected when strengthening).