Windspeed

Visible satellite since daybreak..

Some bad flooding down in the Yucatán.

I've seen eyewalls look a lot worse. Delta seems to be holding its own right now. Surface layer temps drop off a few degrees Celsius from this point forward. However, divergence over the system and poleward mass evacuation of air above 250 hPa is increasing as well. That may help sustain lapse rates to avoid rapid weakening. As has been discussed to death however, VWS is affecting Delta, and that should increase, but not presently enough that the core is overly tilted just yet. That may happen by this evening however. I'd say a borderline Cat 1/2, 90-100 mph landfall this evening is a good call.

The Atlantic Basin has crossed 120 for ACE. By that metric alone, we're above average, but well shy of the 152 to be considered hyperactive by that metric alone. Granted, other metrics, mainly number of storms, number of landfalling hurricanes, etc., it has arguably been a hyperactive year. This year has been anomalous in number of systems intensifying close to land. We haven't really had a lot of long-tracking hurricanes beyond Paulette and Teddy, and even those struggled to maintain intensity long enough to be big ACE producers. After Delta, the long-range may give us a few more systems. Potentially another strong Caribbean system in the last half of October. Perhaps a few weaker central Atlantic systems. But it's going to wind down. I'd say we may squeeze out another 10-15 points to finish somewhere around 135. Again, just based on the ACE metric alone, certainly an active season, but far below what I was expecting. I think I had called for somewhere around ~170.

If the eye will stay warm and clear, beyond the convection being a little more symmetrical, it will help the pressure to fall. The winds should correspond to mixing down better. Awaiting dropsonde data. Also, RE: VWS tomorrow.. Yes, it will eventually be impacting Delta from the west. Noticed this post by Ryan @1900hurricane who hasn't been around on the forum lately.

Color enhanced and classic AVN respectively... Really impressive expansion of the CDO.

Yeah, if it sounds like I am downplaying the wind threat, I apologize. I am just meaning there should be significant weakening versus the temporary maximum intensity Delta is attaining in the short-term. I would be surprised if it makes landfall as a Cat 3 or at least is able to sustain the kind of convection to mix down stronger radial winds aloft at that time. But of course you're correct. Even 60-100 mph gusts is going to be a nightmare for debris and already weakened structures, roofs, etc. Still think surge is the worst danger however due to the ever expanding size and fetch east of the core.

Those folks had short memories. Even after Camille, Frederic and Alicia weren't that long ago and made landfall with closed eyewalls. At any rate, Delta likely will not be a good example of a closed eyewall at landfall by any stretch. Unless 2020 deals to us something completely wack.

I think he meant they were the exceptions.

Laura and Michael both had 29-30°C SSTs right up to the shoreline. Michael's VWS decreased the closer it got to he coast. Laura's increased too late, essentially just after landfall, and wasn't able to disrupt its core. Delta's VWS should be infringing at least 6-9 hours prior to landfall. Some modeling even slows down Delta's forward motion near landfall which could allow shear and cooler SSTs to disrupt the core even further. That being said, Delta's circulation is going to be large and the surge impact will already have been attained regardless if it's falling apart at landfall.

Ring of 80-90°C cloudtops surrounding the eye now.

Yeah again intensification this evening and whatever more Delta can muster by midday tomorrow matters only in fetch for surge. Winds are going to come down by landfall but the radius of 34+ wind is going to continue increasing. This is going to be a surge event.

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

[emoji106]

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..