Windspeed

This is quite noticeable on visible after daybreak. This looks like core convection is consolidating an eyeband. Perhaps Delta finally gives us a clear eye by this evening.

RE: 6z ECMWF; I think it is overdoing it little but it is worth picking up on why. Delta has yet to pass through the best upper divergence and lowest shear it will have in its existence. That begins this afternoon and continues to just before landfall when SSW mid-level flow begins infringing on the core with dry air. That and cooler SSTs should have it weakening significantly into landfall. Whether it is a Cat 3 or a 2 at landfall is a bit trivial as weakening storms do not always mix down winds as effectively as strengthening storms at the same category. The big story will still be the surge Delta builds up this evening and pushes into the coast with a larger circulation.

Best upper tropospheric support to get the most out of the heat content will be this afternoon. That is when I expect significant intensification to begin. Modeling also suggests this, though the magnitude of the 6z ECMWF was a little surprising. I don't expect that degree of RI. But I do think Delta will make a run at Cat 4 even if it may max out as an upper Cat 3. It's going to be a large hurricane regardless.

I don't really see any rapid deepening until tomorrow afternoon when the large core is over the best heat content and best upper tropospheric dynamics.

[emoji2957]

Really? That dude is salivating for GOM Cat 5 more than anyone here. The reality is it will just become a formidable major hurricane again. Not wishcasting, just based on environmental influences here. This is really just dumb. GOL is a good poster.

The preceding shear isn't really going to matter much now. It's essentially size of core and how much time it will have before concentric banding could hypothetically take over. Based on that MW scan, it looks prime for RI.

That's putting it mildly. Granted, GOM upper layer SSTs have come down. But unfortunately upper spreading divergence is bonkers. Delta's vortex is going to intensify rapidly. 28+SSTs are perfect for the kind of poleward outflow it will experience. Simply put, it's entering a hyped environment. Lapse rates are on steroids. Think this reattains Category 4 but as a much larger hurricane.

Umm.. That didn't take long.

Pay close attention to the high cirrus flow, not the low and mid level clouds that are expanding west within the growing circulation. You will see that they are beginning to race poleward. That is due to the setup of the westward extension of 200 hPa upper heights over the E GOM. This should increase ventilation away and evacuate mass as Delta moves further WNW to NW this evening.

Delta's structure is improving considerably by the hour even with half of its circulation still over the Yucatán. Notice poleward upper level outflow increasing and significant expansion of an actual CDO. Delta looks primed to intensify once the core pulls away from the coast.

6z HWRF has a very large hurricane with a large circulation coming ashore. Likely a Cat 2 intensity-wise at landfall, but after having reached 939 mb in the central GOM. If that verifies, the surge impacts are going to be brutal.

There is an upper ridge over the E GOM where the influence of upper ENE flow combined with strong mid-level flow had Delta in a region of higher shear the past 18 hours. Shear should (stating at least based on modeling because that hasn't worked out great as of late [emoji849]) weaken as Delta moves under the western extension of the upper ridge. A strong poleward jet outflow channel will become dominate at the 200 hPa level over the ECONUS downstream to enhance Delta's outflow. SSTs are still quite warm, 29-30°C in the central GOM along the forecast track. If Delta manages to maintain good internal structure, it could go through a second round of rapid intensification somewhere within the 24-60 hrs range before moving over cooler 26-27°C surface layer just south of the north-central GOM.

It's difficult to make much out of Delta's internal structure at that range from Cuban radar.

It's pretty ridiculous that populated regions and resort cities like Cancun and Playa del Carmen still do not have their own weather radar system. Cancun has an international corporate influence and infrastructure now, and it being in a prime Western Caribbean locale for powerful hurricanes, you'd think some of these companies would try help get an adequate radar system down there. We're only 20 years into the 21st Century. I realize Cuba has a radar that reaches the NE Yucatán but it's at a long-distance and attenuated.

Delta might be a good candidate for fastest rapid intensification into rapid weakening within a 24 hour period. lol..

Divergence aloft is just crazy right now. The atmospheric uplift over high heat content is going to continue allowing Delta to fight even the very strong mid level directional shear vector. That being said, as soon as the shear begins to abate, it could rapidly recore and expand. I think it's way too quick to give up on the potential here. Not that anyone is doing that. This may still go bananas NW of the Yucatán by the time it reaches the west-central GOM. If shear backs down a little faster tomorrow, it could even start reintensifying just prior to landfall near the NE Yucatán. But there is no doubt intensification tonight is off the table and also any chance of a Cat 5. If nothing else, a rare micro-cane Cat 4 without a clear eye but reliant on a very small extreme convective eyeband. Without recon or obs, we'd have never known it based on satellite alone.

¯\_(ツ)_/¯ GFS and ECMWF trend the past few days didn't really have any upper or mid level shear until the 12z run. Past few days had very light VWS beyond the steering flow. So I guess using models to forecast is chaotic at best these days. Might as well pound me head against an anemometer.

[emoji3595] Great post. Welcome to the forum. Some kind of internal structural change has been underway. I expect recon to find a temporarily weaker vortex but larger RMW. That being said, it's still a small hurricane. For Cancun/Cozumel's sake, perhaps it weakens and levels off instead of actually pushing a Cat 5. But it's still got a lot of time left for a better organized eyewall to rapidly deepen beyond what the syatem has already experienced. Likewise, there was talk of mid-level en-easterly shear. Unsure how legit 10 kts is having on it since it is moving with flow but then again, unsure how much gyre motion with Gamma's remnant guts is taken into account here.