ATL: ERNESTO - Post-Tropical - Discussion

[cheezyWXguy]

Absurd amount of lightning in the core over the last hour. Radar velocities jumped up at the same time the lightning started too.

Unless I'm mistaken, it looks like most of the lighting was actually taking place in the (disorganized) huge convective blob to the south, rather than the actual CDO to the north of Puerto Rico as indicated by NHC's 18.8N location? Still impressive, but not a direct indication of core building.

https://i.postimg.cc/x13JyBMB/50993454.gif

I was looking at radar, at the time there was a big uptick around the circulation center when the latest burst in your loop occurred

[Sciencerocks]

[Kazmit]

Recon is finding borderline hurricane-force winds, but well away from the center.

[aspen]

It kinda seems like there’s a bit of shear and/or dry air lurking around Ernesto and keeping a bit of a cap on it for now.

Models keep showing that Ernesto’s UL environment will degrade late Thursday into Friday, with an ULL becoming displaced to the SW and imparting shear into the system. Some have it simply level off, others show weakening. Either way, Ernesto will probably peak by tomorrow night at the latest.

[Ubuntwo]

It kinda seems like there’s a bit of shear and/or dry air lurking around Ernesto and keeping a bit of a cap on it for now.

Models keep showing that Ernesto’s UL environment will degrade late Thursday into Friday, with an ULL becoming displaced to the SW and imparting shear into the system. Some have it simply level off, others show weakening. Either way, Ernesto will probably peak by tomorrow night at the latest.

I don’t see this storm peaking tomorrow night, and definitely not earlier. It will almost certainly have a well-developed core offering some resiliency to steadily increasing shear. Shear also appears to drop moving into Saturday from around 25 knots to as low as 10 knots on a multi model consensus before climbing again, so there is a second window for deepening.

[underthwx]

Good morning everyone!......Luis.....how are the weather conditions in your area?.....stay safe....and hopefully the cyclone will exit your area quickly!....

[cheezyWXguy]

That burst on the northern eyewall is likely the kickoff to the phase where towers start rotating around. I’m expecting a significantly improved appearance by tonight.

[Craters]

Anyone know what that is to the NW of Ernesto, looks like an outflow boundary but dont see a reason for it to pop such a strong one at this time

https://i.imgur.com/wRvQUhp.gif

There’s some leftover SAL to its NW that accompanied Ernesto when it first came off the coast of Africa. Since there’s little to no shear, the dry air stayed away from Ernesto’s moisture envelope.

If you don't mind my asking, how does the shear factor into whether the dry air makes it into the circulation or not? There were discussions about that during Beryl, but I didn't get to ask the question back then. (I was too busy battening down the house's hatches and stuff before it hit.)

Thanks!

[aspen]

The 11am discussion mentions the shear on the models that I’ve brought up a few times before. I still think it’s quite possible Ernesto just misses out on MH intensity as a result.

Although Ernesto is moving over very warm waters, the hurricane
might have to deal with bouts of increased shear and nearby dry
air during the next several days. That said, the intensity
guidance shows continued gradual strengthening, and the official
forecast still reflects the possibility of Ernesto becoming a major
hurricane in about 48 hours. Much of the intensity guidance has
come down on the peak intensity this cycle, but for now we'll
maintain continuity and wait to see if this trend continues.

[MarioProtVI]

The 11am discussion mentions the shear on the models that I’ve brought up a few times before. I still think it’s quite possible Ernesto just misses out on MH intensity as a result.

Although Ernesto is moving over very warm waters, the hurricane
might have to deal with bouts of increased shear and nearby dry
air during the next several days. That said, the intensity
guidance shows continued gradual strengthening, and the official
forecast still reflects the possibility of Ernesto becoming a major
hurricane in about 48 hours. Much of the intensity guidance has
come down on the peak intensity this cycle, but for now we'll
maintain continuity and wait to see if this trend continues.

I think the down tick is because Ernesto is taking a bit slower than they expected. If Ernesto significantly improves by tonight appearance wise (which is likely IMO) and has a concentrated wind field, I think they will keep it. Large C3s are a thing (see Larry, etc) it’s just C4+ that’s hard.

[Teban54]

That burst on the northern eyewall is likely the kickoff to the phase where towers start rotating around. I’m expecting a significantly improved appearance by tonight.

Look like that burst is still fighting dry air. However, I had the same thoughts about Ampil in the WPAC yesterday, and it had just cleared out an eye moments ago.

Meanwhile, in case anyone hadn't noticed, 11am advisory upgrades it to a hurricane:

BULLETIN
Hurricane Ernesto Advisory Number 12
NWS National Hurricane Center Miami FL AL052024
1100 AM AST Wed Aug 14 2024

...ERNESTO BECOMES A HURRICANE NORTH OF PUERTO RICO...
...SIGNIFICANT FLOODING LIKELY ACROSS PUERTO RICO AND THE VIRGIN
ISLANDS AS HEAVY RAINS PERSIST...


SUMMARY OF 1100 AM AST...1500 UTC...INFORMATION
-----------------------------------------------
LOCATION...20.5N 67.6W
ABOUT 175 MI...280 KM NW OF SAN JUAN PUERTO RICO
ABOUT 835 MI...1340 KM SSW OF BERMUDA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NW OR 310 DEGREES AT 16 MPH...26 KM/H
MINIMUM CENTRAL PRESSURE...991 MB...29.27 INCHES

[Teban54]

I think the down tick is because Ernesto is taking a bit slower than they expected.

Ernesto officially became a hurricane today at 1500z. That's almost exactly what yesterday's 11am and 11pm advisories were calling for (65 kts at 12z); the 11am advisory was the first to show a hurricane immediately north of PR, and was explicitly noted to be more aggressive than previous ones, which generally didn't have an H until 0z 8/15.

Yesterday's 5pm advisory was the only one that may have ended up overly aggressive, as it had 65 kt at 6z and 75 kt at 18z. But that may also easily be an interpolation issue.

In short, I don't think Ernesto is really intensifying more slowly than the NHC forecasts, nor that it matters much in the long term.

[TheBurn]

[cycloneye]

 https://x.com/philklotzbach/status/1823742274528006241

[Sciencerocks]

[InfernoFlameCat]

Big burst of convection over the center. I am curious if Ernesto will RI.

[Ubuntwo]

Big burst of convection over the center. I am curious if Ernesto will RI.

It technically did hit RI criteria between yesterday and today’s 5 AM - 35 kt to 60 kt.

[abajan]

https://i.imgur.com/lIIqdYg.gif

Interesting to see the east-to-west progression of what appear to be flash-flood warnings in Puerto Rico.

[Nimbus]

Ernesto made it far enough west that he can pull moist inflow up through the Mona passage.
The island land mass of Puerto Rico was inhibiting overnight.

[TallyTracker]

The convection is still pulsing rather than holding steady. That’s definitely a sign of some dry air intrusion. Until that is mixed out and a closed core established, only slow strengthening is likely to occur IMO.