NATL: MELISSA - Hurricane - Discussion

[Sanibel]

Outflow feathering NW quadrant...

[eastcoastFL]

Looking at Jamaican radar right now there's some pretty clear wobbles due west.

[ThomasW]

Seems odd that the pressure's barely dropping per recon. Maybe early EWRC onset based on that radar data?

[cycloneye]

Breaking: Looks like the AF plane has issues as it returns to Curacao and will not make a pass before the 11 AM advisory.

[GCANE]

ARCHER is calling Hurricane

https://tropic.ssec.wisc.edu/real-time/ ... ndex.shtml

[cheezyWXguy]

Seems odd that the pressure's barely dropping per recon. Maybe early EWRC onset based on that radar data?

Since we haven’t really had an eyewall until recently, it’s probably more apt to call it continued core consolidation, but yeah this is probably the hold up at the moment. Maybe some dry air entrainment or remnant effects from the shear last night slowing the rate of strengthening. I think this will work itself out over the next few hours.

[Hypercane_Kyle]

ARCHER is calling Hurricane

https://tropic.ssec.wisc.edu/real-time/ ... ndex.shtml

Even if it's borderline I'd imagine the NHC will upgrade at this point for messaging... because it's clear within an hour or two of becoming one regardless.

[cycloneye]

There will be a gap of a few hours without recon data until the next two missions get going late this afternoon and evening.

[cycloneye]

From the 11 AM discussion:

The peak flight level winds at 700 mb were up to 68 kt.
Using a standard 0.9 adjustment factor to surface winds yields an
intensity of 60 kt, but Melissa could become a hurricane at any
time, as other satellite intensity estimates already support a
higher value.

[BobHarlem]

Discussion on intensity:

it appears likely that a period of rapid intensification
will occur as the storm moves slowly over very warm ocean waters
(30-31C sea-surface temperatures) which is also over the highest
oceanic heat content in the entire Atlantic basin, which will limit
initial ocean upwelling under the slow moving storm. Similar to the
previous cycles, roughly 40/50 Google DeepMind ensemble members show
Melissa becoming a Category 5. While I am not ready to forecast that
intensity yet given the track uncertainty, that remains a
possibility

[ronjon]

NHC is projecting a high end CAT 4 at 150 mph winds for the Jamaican landfall. Only 5 mph lower than a CAT 5. And really what's the practical difference at those high winds. Like a large tornado hitting the island.

[ChrisH-UK]

This is the Optical Depth product from GOES-19 with a 1 hout loop of the meso sector. In the las few frames you can see a change in the clouds from bubbling randomly to been organised into Melissa's rotation.

GOES-19 Red Band + Optical Depth

[Travorum]

My guess on the steady pressure is dry air entrainment disrupting development of the NE eyewall. Based on the last VDM reporting a closed eyewall and the convection wrapping up that way it should be worked out pretty quickly.



Edit: also cyan ring in the 37ghz scan.

[Hurricane2022]

We should see a small and beautiful eye opening later tonight.

[Hypercane_Kyle]

I'm surprised they didn't pull the trigger on hurricane, regardless should be one by 2pm.

[cheezyWXguy]

My guess on the steady pressure is dry air entrainment disrupting development of the NE eyewall. Based on the last VDM reporting a closed eyewall and the convection wrapping up that way it should be worked out pretty quickly.

https://i.imgur.com/VGzbyay.jpeg

https://i.imgur.com/rW54EOk.png

Edit: also cyan ring in the 37ghz scan.

Yeah I think that dry air entrainment led to the development of that prominent band on the eastern side which is competing for energy. Seems to be starting to lose influence now though as new cells pop up in that dry slot on the SE side

[cycloneye]

The inteprid Josh once again will go to chase a biggie, this time in Jamaica.

 https://x.com/iCyclone/status/1982103189685244193

[USTropics]

My guess on the steady pressure is dry air entrainment disrupting development of the NE eyewall. Based on the last VDM reporting a closed eyewall and the convection wrapping up that way it should be worked out pretty quickly.

https://i.imgur.com/VGzbyay.jpeg

https://i.imgur.com/rW54EOk.png

Edit: also cyan ring in the 37ghz scan.

I'm impressed with the HAFS-A grasp on the evolution of Melissa over the past few days. It was one of the few models that captured the eastern reformation yesterday morning:


It's pretty much nailed the slight dry slot like you alluded to here:


The model had a large upgrade over the summer to 2.0, some of the highlights:

• Improved Model Initialization: Enhanced vortex cycling and data assimilation techniques to better incorporate real-time observations, reducing initialization errors in the storm's core structure.
• Upgraded Model Physics: Refinements to physical parameterizations for cloud microphysics, boundary layer processes, and eyewall dynamics, leading to more realistic simulations of storm evolution.
• Higher-Resolution Nesting: The moving nest now supports finer grid resolutions (down to ~1-3 km in the inner domain), improving depiction of small-scale features like rainbands and tornado genesis.

You can play around with some of the new experimental stuff here as well - https://storm.aoml.noaa.gov/viewer/

[BobHarlem]

Jamaica radar since the eye was visible on both sides on it.

[IsabelaWeather]

NHC is projecting a high end CAT 4 at 150 mph winds for the Jamaican landfall. Only 5 mph lower than a CAT 5. And really what's the practical difference at those high winds. Like a large tornado hitting the island.

Technically its 6mph shy, but in reality its 10 mph shy.