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Windspeed

Hurricane Zeta

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3 hours ago, jbenedet said:

Core is intact and offshore.

zeta looks quite healthy and symmetrical.
 

Looks better than Delta did at same time...from what I recall...

Yeah that was my first thought when I looked today.  Can anyone explain the conservative LF intensity forecasts?  I can see the low OHC in the northern gulf inducing some weakening before landfall, but what's stopping ζ from just taking off in the meantime?

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Zeta has developed an extremely impressive outflow pattern since last night. However, convection is struggling mightily near the core and a large moat has developed between the central convection and a cyclonically curved outer band. I believe we’ll see the outer band structure decay over the next 12 hours and an increase in convection over the center as that occurs. SST are sufficient and with the outflow pattern, I do expect strengthening to occur. However, the system took more of a hit over land than it seemed while over land. This spread out structure will take much longer to coalesce and see a quick uptick in intensity. I predict a slowly organizing system to peak and then stay at similar intensity through landfall. Probably on the order of 70-80kts. If this had a better structure I would be concerned of a stronger system but it will take considerable time to reorganize in its current state 

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4 minutes ago, NorthHillsWx said:

Zeta has developed an extremely impressive outflow pattern since last night. However, convection is struggling mightily near the core and a large moat has developed between the central convection and a cyclonically curved outer band. I believe we’ll see the outer band structure decay over the next 12 hours and an increase in convection over the center as that occurs. SST are sufficient and with the outflow pattern, I do expect strengthening to occur. However, the system took more of a hit over land than it seemed while over land. This spread out structure will take much longer to coalesce and see a quick uptick in intensity. I predict a slowly organizing system to peak and then stay at similar intensity through landfall. Probably on the order of 70-80kts. If this had a better structure I would be concerned of a stronger system but it will take considerable time to reorganize in its current state 

My exact thinking. The circulation is broad and the core took a hard hit over land. On visible the LLC can be seen pretty exposed. Zeta has a lot of work to do. Dry air really has worked in. It definitely has ripe conditions for strengthening but will it organize in time to take advantage of the environment. I'm feeling doubtful with it's current structure and lack of very deep convection near LLC. Only time can tell but I agree if this were better organized a more significant hurricane would be possible but imo the ceiling is probably a strong cat 1 unless it rapidly gets itself together tonight. 

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10 minutes ago, NorthHillsWx said:

Zeta has developed an extremely impressive outflow pattern since last night. However, convection is struggling mightily near the core and a large moat has developed between the central convection and a cyclonically curved outer band. I believe we’ll see the outer band structure decay over the next 12 hours and an increase in convection over the center as that occurs. SST are sufficient and with the outflow pattern, I do expect strengthening to occur. However, the system took more of a hit over land than it seemed while over land. This spread out structure will take much longer to coalesce and see a quick uptick in intensity. I predict a slowly organizing system to peak and then stay at similar intensity through landfall. Probably on the order of 70-80kts. If this had a better structure I would be concerned of a stronger system but it will take considerable time to reorganize in its current state 

I'm starting to see a pattern where for every hour a hurricane spends over land, it takes about 1 hour to reorganize (assuming good conditions). Zeta was over land for about 12 hours.

 

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27 minutes ago, StormChaser4Life said:

That certainly has dropped from earlier and honestly not surprised given how it looks

New, stronger convection is beginning to fire near and around the center. The next 8-10 hours should give us a good idea where the intensity bar is set, though I still think there are enough positive factors going for this to be a stronger system than what these show. I like 70-80kts 

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The central GOM, NW of the Yucatán is still conducive for high lapse rates and would support a major. The trek north of that however will depend on how cold upper tropospheric jet entry is with the digging trough. I guess we'll find out just how much 26°C can muster. The hurricane will be hauling ass at that point however and starting to feel baroclinic forcing. This is going to be an impactful event well inland due to the synoptic setup regardless of official landfall intensity.

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Within the span of a few hours Zeta has materialized 3/4 of an eyewall, once it closes it off I expect fairly steady to quick strengthening. This is a huge system, and once it fully develops I expect it will be larger than both Delta and Laura

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Definitely the best Zeta has looked since it came off the Yucatan. Major convective burst that's trying to wrap around the LLC. Curious to see how strong it will get the next 24hrs while it's in the best conditions for strengthening 

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Honestly, I'm going to go crazy and forecast this thing becomes a moderate Cat 2. None of the intensity guidance shows that, and I care 0%. The environment is excellent and I don't see dry air entrainment. The eyewall that's developing is solid, and I actually think the outer bands are helpful in keeping the interior of the system more stable. Less chance for some unknown shear to work in, less chance for extra dry air to work in. Whatever happens here, it will absolutely beat the intensity guidance. As for why the guidance is low, few possible reasons but frankly my best guess is low initial intensity. I've watched the guidance forecasts all season and they rise and fall in line with the ingested initial intensity. The thing is, it does NOT take THAT much to get a storm to grow stronger in a low shear, high water temp, moist environment, and you have better than chance odds by betting above the model consensus.  If the eye feature closes off, which it looks poised to do, ya know, go nuts. 

 

As I've said all along, I'm definitely most interested in what this thing does inland when it phases with the continental low ejecting from the rockies. Very Isaias/Sandy-esq in the sense of baroclinic interaction maintaining strength for a LONG time. This storm won't produce 40" in a single spot, but the phasing is going to mean tens of millions of americans are going to see significant impacts from these storms. 2, 4, 6" of rain, some areas a couple feet of snow...these are large totals and will cause widespread spatially, but not dense, power failures, flooding, wind damage, etc over a HUGE swath of the eastern CONUS. Obviously you're also ingesting a bunch of vorticity, and if you take that, add some moisture, jet streak and a strong llj, you'll see a touch more tornado potential than with your average hurricane. Whenever a barotropic system phases with a baroclinic system, things get interesting. 

 

MU

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3 minutes ago, Moderately Unstable said:

Honestly, I'm going to go crazy and forecast this thing becomes a moderate Cat 2. None of the intensity guidance shows that, and I care 0%. The environment is excellent and I don't see dry air entrainment. The eyewall that's developing is solid, and I actually think the outer bands are helpful in keeping the interior of the system more stable. Less chance for some unknown shear to work in, less chance for extra dry air to work in. Whatever happens here, it will absolutely beat the intensity guidance. As for why the guidance is low, few possible reasons but frankly my best guess is low initial intensity. I've watched the guidance forecasts all season and they rise and fall in line with the ingested initial intensity. The thing is, it does NOT take THAT much to get a storm to grow stronger in a low shear, high water temp, moist environment, and you have better than chance odds by betting above the model consensus.  If the eye feature closes off, which it looks poised to do, ya know, go nuts. 

 

As I've said all along, I'm definitely most interested in what this thing does inland when it phases with the continental low ejecting from the rockies. Very Isaias/Sandy-esq in the sense of baroclinic interaction maintaining strength for a LONG time. This storm won't produce 40" in a single spot, but the phasing is going to mean tens of millions of americans are going to see significant impacts from these storms. 2, 4, 6" of rain, some areas a couple feet of snow...these are large totals and will cause widespread spatially, but not dense, power failures, flooding, wind damage, etc over a HUGE swath of the eastern CONUS. Obviously you're also ingesting a bunch of vorticity, and if you take that, add some moisture, jet streak and a strong llj, you'll see a touch more tornado potential than with your average hurricane. Whenever a barotropic system phases with a baroclinic system, things get interesting. 

 

MU

Red state sandy

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23 minutes ago, brentrich said:

OOOOHHHHH........... Cat 3 brewing????

 HWRF doing a good job teasing.

gHDDlkO.png

 

 

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Even with the cold upper dynamics, I am still not buying anything lower than 970 hPa landfall. It's just really difficult for 26°C SSTs to pull that off and there may be strong mid-level flow to advect Theta-E dry air intrusion by landfall. Again, this is semantics and the real beef may be during ET transition post landfall. Yes, Zeta could go nuts the next 24 hrs, but it's probably not going to hold that intensity through landfall. That doesn't mean to downplay the post-landfall event at all since it matters not.

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I agree with Windspeed's statement on landfall in large part. I think as with many things, stronger peak equals stronger arrival...BUT, in the same way that I think the current environment is strongly favorable for strengthening, I think the near-coast environment is pretty clearly not. The upper level pattern will be favorable and that will keep the system stronger than it might otherwise be, but it's hard to expect it to hit at peak intensity. That said, it may not weaken as much as we think it should--so whether or not sub-970 is possible at landfall is really a question of what it peaks at. It won't be in a hostile environment, just not a great environment. The question isn't, can it strengthen, it's can it hold together. The guidance is pretty solid in saying, "hey I don't think this is going to weaken a ton". It's saying that expecting a tropical storm, not a cat 3, so take that fwiw, but I do trust models to do OK with their upper level dynamics. Either way my feeling is, follow the physics. Models are guidance, not gospel. Helpful tools, show trends and tracks...but if you see a duck and the models say it's a cow, I'm going to treat it as a duck. I buy trends...that it won't weaken close to landfall a ton, but I also think the stronger it gets, the harder it will be to sustain that strength. In other news, the current ADT CI number is 3.0, estimated Vmax 45 knots, and it has the weakening flag ON. This is why I don't put tons of stock into automated dvorak numbers. Sometimes, very useful. Other times, not so much. Separate aside: I'm not sure what's up with the AF hurricane hunters the last few days. Last night it looked like they turned back after flying out for around 45 minutes, today data reporting stopped after around 20 minutes of flying from the base. Unusual. Also unfortunate since it's a useful way to monitor the overall environment.

 

MU

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That's a nice cyan ring on microwave there, great outflow pattern too. Probably a decent shot at a stint of RI during diurnal max upcoming.

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1 hour ago, Moderately Unstable said:

...Whenever a barotropic system phases with a baroclinic system, things get interesting. 

 

MU

Of course, the phase has to actually happen. We thought that was going to happen with Cristobal and it was a big ol' nothingburger around here despite being the first actual warm-core cyclone to track through Wisconsin since the remnants of Gilbert in 1988, and setting a record low June MSLP at KMSN.

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according to the weather channel the pressure of zeta has come up to 990 which would indicate weakening while on radar it looks like it is strengthening hmm..

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Of course, the phase has to actually happen. We thought that was going to happen with Cristobal and it was a big ol' nothingburger around here despite being the first actual warm-core cyclone to track through Wisconsin since the remnants of Gilbert in 1988, and setting a record low June MSLP at KMSN.
Much colder and stronger mid-level digging trough. I think this is going to play right into modeling.

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Pretty amazing we’re looking at our 6th US hurricane landfall this season. I know they haven’t all been blockbusters but Laura, delta, Isaias, sally, and now probably zeta would be bonafide headliners by themselves in any season on this forum. We’re spoiled 

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according to the weather channel the pressure of zeta has come up to 990 which would indicate weakening while on radar it looks like it is strengthening hmm..
I'd say this rise is temporary due to reorganization of the convective band currently wrapping the vortex that was evident on MW. Zeta's core still has 24 hours over good OHC to deepen.
8827fb319026420580f6b9672602ab52.gif
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1 minute ago, Windspeed said:

I'd say this rise is temporary due to reorganization of the convective band currently wrapping the vortex that was evident on MW. Zeta's core still has 24 hours over good OHC to deepen.
8827fb319026420580f6b9672602ab52.gif

Agreed. If this convective flare up persists, it seems it will, those pressures will come down quick. That’s a large amount of heat being expelled into the atmosphere 

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The eye is wrapping up fairly quickly.   

Probably only has 8hrs left over the warm ssts. Shear kicks in in about 21hrs. 100 miles south of the LA coast.  

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36 minutes ago, PSLwx said:

Has Atlanta ever been under a Tropical Storm Watch before?

I think Irma was the first Tropical Storm Warning.

Edit: "Breaking News: Hundreds of Storm Chasers descend on Atlanta to film Tropical Storm Zeta approach Atlanta!"

Party!!! :)

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