Teban54 wrote:cheezyWXguy wrote:Teban54 wrote:I could be reading too much into this, but...
A new burst of eyewall convection just appeared, immediately next to the "dry air channel" and near the convective blob. It's the strongest that I recall seeing this morning.
Could this be an attempt at shielding off the dry air and reintensifying?
https://i.imgur.com/05iLUyU.gif
I think this is true. Yesterday when this occurred, it seemed to follow this order of events:
1- prominent band forms, initially as a discrete blob, near the periphery of the cdo. Intensification levels off.
2- blob stretches into more of a classic band appearance, a moat between this band and the cdo becomes apparent.
3- new cells appear in the moat, eventually filling in as the original prominent band is gradually pushed farther away from the cdo and begins to lose influence.
4- new bursts begin to appear in the cdo/eyewall as the prominent band continues to weaken.
5- intensification resumes as eyewall bursts become stronger and band weakens further/dissipates.
If this is a repeatable sequence of events for today, I think we’re at the 4th point by now. We should watch to see if the band gets further removed from the core, new banding forms in the dry moat, and if new bursts continue to occur in the eyewall over the next couple hours.
I think you're onto something. From the loop below, you can also see the new burst attempting to quickly turn itself into the new CDO (which has wrapped around 70% of the eyewall since the last frame of the loop). The blob is also showing clear separation from the core: Melissa's center has been slowly drifting W, while the blob remained somewhat stationary.
https://i.imgur.com/hWMlJhF.gif This is quite similar to the huge burst yesterday that kickstarted the ERI (
the loop here shows the whole process). For reference, the start of this loop was exactly when
USTropics wrote the detailed explanation, which was quoted again upthread.
The main differences I see are:
- When the burst happened yesterday, the nearby blob has already greatly weakened. (You can see initial stages of that blob here a few hours earlier.) Right now, however, the SE quad of the blog is still quite active even when the new burst is already wrapping around.
- This process yesterday happened when Melissa was still a minimal hurricane. Since it's at a much higher intensity now, EWRC (or at least eyewall melds) may complicate things.
I think both of these explanations are really good for some of the inner dynamics we are seeing. We're also not getting a true VHT here, but rather a strong vertical ascent along the entire periphery of the inner core in these regions (essentially full on vertical ascent of the inner core). We would typically see this degrade as we wrap around upshear (northwest and southwest regions) and away from the more unstable environment (aided by the drier air mass entrainment region), but that's not always the case like you stated.
Zooming out some, the undercutting shear limiting the outflow is definitely a contributing issue here as well. Conservation of mass (i.e., air can't be created or destroyed), so we limited advection away from the center of the cyclone and sinks -> we limit how much air Melissa's updrafts can evacuate -> we are capping her MPI.
I think there is some
slight restrictions to inflow due to the eastern topography of Jamaica occurring as well (in addition to a drier background state to the west of Melissa). You can see it here in the surface flow:
Also in this 100 frame meso-loop, the convection immediately collapses as it hits the coast (with no landmass, some of this moisture-laden inflow would reach Melissa):
It's a very minor factor given Melissa's more southern position, but something to consider here given current longitude position.
