2020 Atlantic Hurricane Season

[Prospero]

26 minutes ago, NavarreDon said:

Someone probably needs to open a dedicated thread on 92L. It’s got its cherry on the 5 day outlook.

 

I swear I moved my mouse over the image expecting the popup window! LOL

[hawkeye_wx]

92L has developed a decent circulation.  Better convection and a decrease in shear over the 24-36 hours should allow it to organize.  The new GFS is more robust, strengthening it to hurricane in the gulf with a landfall on the central gulf coast in a steady/weakening phase.

[hlcater]

I’m pretty bullish on this one relatively speaking so went ahead and made a thread. 

[cptcatz]

On 9/30/2020 at 2:15 PM, Amped said:

 

GFS Para is the new 3km NAM, it's done this all season. 

Yeah I know the whole a broken clock is still right twice a day thing but the GFS-P was the only model that was consistently showing Delta developing into a significant hurricane in the long range.  

[STxVortex]

FYI-  I suspect that comment by tzav77 above, with the 'bitly' links, may be a potentially nasty viral trap. Admins should check it out, safely of course.

Nobody should ever trust those re-directive 'abbreviated' links on a public board from an unknown poster.

[MJO812]

Active times on the models

[SnowLover22]

Any signs of activity after Delta?

[cptcatz]

2 hours ago, SnowLover22 said:

Any signs of activity after Delta?

GEFS is showing a big Caribbean signal during the last couple weeks of October

[StormchaserChuck!]

What's the last letter?

[cptcatz]

6z GEFS continues to show the signal around October 19

[salbers]

The feature spinning south of Cuba looks interesting - on satellite right now.

[Prospero]

9 minutes ago, salbers said:

The feature spinning south of Cuba looks interesting - on satellite right now.

Hello Epsilon...

[cptcatz]

40 minutes ago, salbers said:

The feature spinning south of Cuba looks interesting - on satellite right now.

Well that's interesting. I wonder if NHC will mark it at 8pm. It's got a clear tight circulation going on. 

[Moderately Unstable]

Lol, well, in the shorter term, there's Invest 96E off the African coast that has a decent surface circulation and actually had some significantly organized outflow going on earlier this afternoon, but it's a little less vigorous right now with the deep convection more displaced from the center to the west due to shear. It has a couple days of ok conditions to strengthen but then may struggle. Plenty of possible places for epsilon. 

[Windspeed]

Well that's interesting. I wonder if NHC will mark it at 8pm. It's got a clear tight circulation going on. 

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.

[cptcatz]

10 minutes ago, Windspeed said:

19 minutes ago, cptcatz said:

Well that's interesting. I wonder if NHC will mark it at 8pm. It's got a clear tight circulation going on. 

 

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.

I wasn't being facetious. I'm still new to weather stuff and didn't know all that you just explained. 

[Windspeed]

I wasn't being facetious. I'm still new to weather stuff and didn't know all that you just explained. 

[Windspeed]

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.

[Moderately Unstable]

28 minutes ago, Windspeed said:

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.

Well, it is 2020, so, hey, ya never know. I think this may be a bit more reflective of the inherent limitations of the ACE metric than an indicator that the season wasn't hyperactive. With any index, you almost invariably have some kind of bias. If you weight by, say, rainfall produced, you'll get a different measure than using wind speeds. If you measure by number of hurricanes landfalling on the us coast, that's again another number. For the us population, I'd say that last one probably makes the most impact. That said, it is notable that despite this season surpassing 2005, which had the 2nd highest recorded ACE since record keeping began (250), this season has seen a prodigious number of storms but very much lacked in terms of intensity. The ironic thing here is what happened is antithetical to the current going climate change hypothesis (of which I used to be a researcher). The modeling shows, generally, less storms, but more intense ones. Though lately there's some back and forth on that. This year we've seen more storms, but less intensity. I don't view that as an indicator of lack of climate change though. More that weather doesn't exist in a vacuum. Developing La Nina and various teleconnection phases play a role. 

 

In any case, I think it's likely safe (but 2020 again so, lmao, who knows), to assume that Delta is the last of the long track high-impact majors of this season. I don't think we can say with certainty it is the last major *period*, as the Caribbean is still warm as you allude to. We also can't say it is the last US impacting storm. Sandy was October, Michael was October. The reason it could be the last major impacting the us has to do with the water temps along the gulf coast and Florida. If another major hit it would need to hit Florida, probably the southern part, so it's statistically unlikely just because of the number of things that would have to go "right". You also still can't totally count out the mid-atlantic. We still have a ways to go, so a useful metric if one were able to find it, would be seeing comparable average and hyperactive ace scores *to date*, rather than for the season as a whole. That would better articulate how above/below we are tracking relative to a hyperactive season based on wind intensity. The thing that retards long track cape verde storms, and storms in general, this time forwards, is shear. Certain parts of the ocean are still warm enough to support tropical development and will remain so, likely, for a couple more months. In my research experience, things like the MJO and other teleconnection phases are useful when it comes to figuring out when the jet stream will be more zonal, more meridional, faster slower. Thus, it is conceivable to hit 152 still. One notable thing here is that the ace index biases towards intense cyclones, since the wind speed is squared in the calculation. That means the ace score is parabolic (exponential, though I like saying parabolic as it is more specific) with increasing storm intensity, not linear. I'm not sure that's the *wrong* approach to take (you have to weight things somehow), but, I think this season will be considered hyperactive regardless of the final ace score. 

 

MU

[Amped]

On 10/8/2020 at 10:20 AM, cptcatz said:

6z GEFS continues to show the signal around October 19

00z GEPS and 12z GEFS show something also. 19th-23rd timeframe.

[friedmators]

#throwback


.

[CheeselandSkies]

Michael was basically the unicorn of landfalls. In the CONUS, in daylight, with a perfectly formed stadium eyewall untouched by EWRC or dry air; yet it is barely talked about outside of those it impacted and those who chased it.

[Calderon]

14 minutes ago, CheeselandSkies said:

Michael was basically the unicorn of landfalls. In the CONUS, in daylight, with a perfectly formed stadium eyewall untouched by EWRC or dry air; yet it is barely talked about outside of those it impacted and those who chased it.

Had it made landfall 15 miles farther west, it would've easily been a good $5bil more damaging and practically wiped out much of PCB and downtown Panama City with surge. Also would've completely destroyed my parent's place by St. Andrews State Park if not by the 160mph winds then definitely the 14ft surge versus the wind ripping the roof off and ripping siding away.

It was surreal being stationed at Keesler AFB and watching it unfold relatively not far away.

[SnowLover22]

48 minutes ago, Calderon said:

Had it made landfall 15 miles farther west, it would've easily been a good $5bil more damaging and practically wiped out much of PCB and downtown Panama City with surge. Also would've completely destroyed my parent's place by St. Andrews State Park if not by the 160mph winds then definitely the 14ft surge versus the wind ripping the roof off and ripping siding away.

It was surreal being stationed at Keesler AFB and watching it unfold relatively not far away.

I know it was intensifying up until landfall. One can wonder how much stronger it would have gotten if it had another day over water. 185 mph? 190 mph?

[Windspeed]

I know it was intensifying up until landfall. One can wonder how much stronger it would have gotten if it had another day over water. 185 mph? 190 mph?

That's a little complicated to be certain. Granted, speculation here; but two points: 1) It would not have needed a full day at the rate the pressure fall it was experiencing into landfall to have become a more intense hurricane. Between 4:30AM and 10:30AM CDT recon missions recorded a pressure drop from 937 mb to 923 mb. The last pass recorded 919 mb at 12:30PM CDT. A mere six more hours over those above-normal GOM SSTs and exquisite upper tropospheric conditions and it would have likely bottomed out around 910 hPa, taking into account some leveling off as well. At that rate of pressure fall and gradient increase, even nine more hours we would have seen Michael flirt with 150-160 kts (175-185 mph) winds. 2) On the other hand, the eye was also contracting and a concentric band was beginning to form. So given too much more time, very probable that an ERC would have most likely initiated given another full 24 hrs, and we would have likely seen Michael level off and weaken.

[SnowLover22]

1 hour ago, Windspeed said:

6 hours ago, SnowLover22 said:

I know it was intensifying up until landfall. One can wonder how much stronger it would have gotten if it had another day over water. 185 mph? 190 mph?

 

That's a little complicated to be certain. Granted, speculation here; but two points: 1) It would not have needed a full day at the rate the pressure fall it was experiencing into landfall to have become a more intense. Between 4:30AM and 10:30AM CDT recon missions recorded a pressure drop from 937 mb to 923 mb. The last pass recorded 919 mb at 12:30PM CDT. A mere six more hours over those above-normal GOM SSTs and exquisite upper tropospheric conditions and it would have likely bottomed out around 910 hPa, taking into account some leveling off as well. At that rate of pressure fall and gradient increase, even nine more hours we would have seen Michael flirt with 150-160 kts (175-185 mph) winds. 2) On the other hand, the eye was also contracting and a concentric band was beginning to form. So given too much more time, very probable that an ERC would have most likely initiated given another full 24 hrs, and we would have likely seen Michael level off and weaken.

Yeah and I guess it was flirting with MPI so it couldn't have strengthened too much more. Would have naturally leveled off........  even without an ERC.

[wdrag]

Since it's a big year, am looking ahead with proximity to the USA East coast and GMEX.  Epsilon and Zeta appear on the "modeling" horizon in both the GEFS/EPS members between the 17th-26th.  The current NHC outlooked 20% chance is not included, though not ruled out.

Added only GEFS/EPS member sampling next weekend, with more members showing up in the week thereafter.

Eastern GMEX-FL coast still above normal SST. 

Closed this post with a 10 day outlook for DELTA members (06z/SEP 27).... that tended to be closer to FL for 06z/7, but had a few near the Yucatan. 

Overall modeling cues seem to be improving, I think. 

[cptcatz]

^it actually looks like the wave that a number of the models have developing near the Bahamas is the current wave that NHC has at 20%

[Floydbuster]

I still think we could see a November hurricane. By that time, realistically we could be on Hurricane Eta.

[cptcatz]

GFS/GFS-P sure like something forming but they're all over the place with exactly what. The 00z GFS- P shows what may be the largest tropical circulation I think I've ever seen.