Windspeed

Hmm.. Wouldn't have thought W GOM majors were so rare in October.

Excellent post by Philippe Papin: https://twitter.com/pppapin/status/1314350609924067328?s=19

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That's a mid-upper low. It's evolving into a stronger ULL due to backside outflow / TUTT off of Delta. Actually, I think you were being facetious here. Anyway... yeah.

-93°C in those towers within the NW semicircle.

Dakota Smith at CIRA (Atmospheric Research Division at CSU) has the best satellite posts.

Eyewall is closed. With that dropsonde showing 121 kts just above surface level, I'd say strengthening will continue as recon makes more passes. Think this will make a run at Cat 4 during DMAX.

Yeah FL supports upgrade as well. The pressure drop supports upgrade. That is inevitably going to mix down. I'd say based on the pressure drop alone that recon will make several more passes. We have significant intensification in progress.

We'll have a dropsonde and sampling of the NE quadrant in mere minutes.

Recon about to make SW to NE pass. We'll know intensity very soon.

Wow... And just like that, a strong CB went up in the eastern eyewall and is rotating around in the northern semicircle. This has the look of a strong Category 3 hurricane. Need recon.

There's about 8-10 kts of southerly shear. Relatively too weak to prevent intensification but perhaps enough to keep downshear convection weaker as CBs go up and rotate around the eyewall. As Delta turns more northward and gains forward motion, there will be a window tonight (6-12 hrs) where shear is weakest prior to an increase in SSW VVW flow and mid-level shear prior to landfall. That and cooler SSTs should eventually put a halt on whatever intensification is gained by Delta through mid-day tomorrow. That should be prior to landfall.

lol..

Here's an animation of the classic NHC AVN IR colorization...

Heh, was I analyzing frame by frame? How about noting the obviously clear symmetrical eye at the end of that animation and obvious continued improvement. You know, the first clear eye we've had since Delta existed?

963.2 EXTRAP on last pass.

¯\_(ツ)_/¯

Likely response of an intense convective plume going up in the northern to western semicircle creating subsidence in the SE region of the core. That may just as well wrap shortly. Either way the overall structure has improved significantly since early this morning. Recon is about to make another pass. Should know more in just a bit.

Continuing to improve. Really convenient when big structural changes occur during daylight as nothing beats visible.

Eye is showing signs of warming and the high cirrus are starting to respond with dissipation. You can see the sinking motion. Banding / convective plumes in the eyewall are continuing to go up and they look symmetrical as well. All systems go...

Look for an area along the coast to increase in surge height if Delta really gets going by this evening. I think the 7-11 ft could be increased to 12-16 right of the forecasted point of landfall. The 7-11 may be extended further east of that increase as well.

Ike was dealing with significant ENE'rly mid-level shear as it traversed across the north-central GOM. It wasn't enough to force weakening but after Cuba, Ike also had a large circulation. If you will recall, there was an intense westerly eyeband that could not wrap or stay wrapped for symmetry. The convection remained lopsided but intense enough to keep the large circulation chugging along as a big Category 2. Simply put, the battle between shear and thermal dynamics kept Ike at status quo all the way into landfall. Obviously surge was the issue and led us to a new parameter, IKE. Delta on the other hand should have a good window of much more favorable conditions to actually reattain major status while continuing to expand its convective envelope symmetrically up until moving over cooler SSTs and mid-level shear increases prior to landfall. Granted, the end result may be similar for landfall intensity, but Delta's maximum winds should get higher than Ike's maximum winds ever achieved in the GOM. This all being said, surge is going to be the biggest problem at the coast regardless if it maintains Category 3 or weakens to a 2 by landfall. Expansion and fetch will have already been achieved.