Chasing JOVA

[HurricaneJosh]

Hey Josh,

I hope all is continuing to go well for you! I just got finished reviewing your excellent chase "teaser" and thought it was some of your best intercept footage, to date!

If I may, please allow me to share a few brief thoughts (my own best educated guess) concerning the likely intensity of hurricane (H) Jova's maximum winds at your intercept location. First, all of the available meterological data seems very consistent with the NHC's operational intensity of an 85 kt. category two classification for H Jova's landfall along the immediate coastline. From what little I've read online, as well as the damage pics and video footage you've provided, it too seems quite consistent with a "solid" category two maximum intensity (maybe even 90 knots along the immediate coastline), as well.

From what I understand, and read, you were positioned just a couple of nautical miles inland at an elevation of ~73 feet. Although you weren't positioned directly on the shoreline itself, it's fair to recognize that the increased elevation of your specific intercept location-as compared to the standard height of 33 feet above MSL-likely mitigated against the expected decrease in the maximum sustained 1-min. wind (MSW) that would otherwise have been expected, at your own intercept location. Another variable to be taken into consideration would be the openness of the terrain itself. If it wasn't open exposure, that would also play a part in the MSW you experienced-although peak 3-second gusts could still retain their direct landfall intensity.

Since so much of the estimation of the MSW likely experienced at your specific location will invariably rely upon a little more subjectivity than otherwise would've been the case, that too must be taken into consideration. To be more specific, there weren't any reliable measurements of the MSW taken over land. This significant lack of empirical data makes it very difficult to make a reasonably objective estimation of the MSW. I should also note that an accurate measurement of the MSW in any hurricane is difficult to obtain, in and of itself. That's why most NWS offices and companies responsible for performing post-storm damage surveys typically use an estimation of peak 3-second wind gusts, rather than trying to deduce the maximum 1-min wind speeds.

With all the aforementioned taken into consideration, I would suggest that it is more applicable, and likely far more accurate, if one were to determine a best estimate of the peak 3-second wind gusts experienced at a specific locality. In order to make this estimate, we are all limited by the lower visibility associated with a night-time landfall. That aside, the video footage you provided appears to support peak 3-second wind gusts exceeding 87 knots (100 mph). The aforementioned visibility issue makes it very problematic in trying to determine just how much higher those winds might've been. Based on the footage alone, it seems conceivable that the winds may have been comparable to the highest 3-second gusts we experienced in Everglades City during H Wilma. That being said, it's also possible that the maximum 1-minute wind may have even been slightly higher in Jova. Based upon my own intercepts over the years, I've noticed that winds associated with heavier rainfall appears visibly more intense, and even "feels" more intense, than that associated with less rainfall (aside from the concept that heavier rainfall helps bring stronger winds down to the surface). That's why making an accurate comparison between your Wilma chase footage (with very little precipitation in daylight hours) and that of Jova (with heavy precipitation in night-time conditions) is somewhat problematic.

Regardless of just how intense the winds actually were at your intercept location, it's fair to say that you made a VERY successful intercept, and one that appears to be at or very near the top of those you've encountered to date. As a result, you have every reason to be quite proud of the footage you captured!

~Tony

Hey, Tony!

Thanks for the note and your comments! I'm glad you liked the footage. A couple of things:

* The winds/gusts I experienced in Jova were stronger than the winds/gusts I experienced in Wilma. (Remember, at our location in Wilma, peak sustained winds were probably Cat 1. The Cat-3 winds were way down near Cape Sable, and very few people-- if anyone-- experienced Wilma's max winds in FL.) Yes, heavy precip adds a nice visual effect, but that doesn't affect my perception of the speed.

* When you mention "available meteorological data", which data are you referring to, exactly? Except for my pressure reading just outside of the eye, I'm not aware of any other data from Jova's inner core at landfall. (There were no wx stations in the core and the final recon flight was over 9 hr earlier.) If you have any relevant data, please share-- I'd be excited to see it.

* My belief that Jova may have been a little stronger than the operationally assessed 85 kt actually has nothing to do with this video or the winds I saw on the ground. It's actually based on calculations using the cyclone's dimensions (wind radii), environmental and peripheral pressure values, and climatological means (for pressure/wind relationship and RMW). I'll post that analysis here if I get some affirmative feedback from a more authoritative source. (I don't want to post it unless it's deemed to be sound methodologically.)

* Whatever Jova's landfall intensity, the winds would have been lower at our location (the center of a town a couple of mi inland) for the usual reasons. Only a tiny area over water or right at the open coast-- if anywhere at all-- experiences the "best-track" wind speed when a hurricane makes landfall. For this reason, you can't use this footage to put a ceiling on the cyclone's peak winds. The footage shows that Jova's max winds were at least this strong.

[aslkahuna]

A minor point perhaps, but when we talk about 1 min winds at 10m, we are talking about 10m AGL not MSL.

Steve

[ncforecaster89]

Hey, Tony!

Thanks for the note and your comments! I'm glad you liked the footage. A couple of things:

* The winds/gusts I experienced in Jova were stronger than the winds/gusts I experienced in Wilma. (Remember, at our location in Wilma, peak sustained winds were probably Cat 1. The Cat-3 winds were way down near Cape Sable, and very few people-- if anyone-- experienced Wilma's max winds in FL.) Yes, heavy precip adds a nice visual effect, but that doesn't affect my perception of the speed.

* When you mention "available meteorological data", which data are you referring to, exactly? Except for my pressure reading just outside of the eye, I'm not aware of any other data from Jova's inner core at landfall. (There were no wx stations in the core and the final recon flight was over 9 hr earlier.) If you have any relevant data, please share-- I'd be excited to see it.

* My belief that Jova may have been a little stronger than the operationally assessed 85 kt actually has nothing to do with this video or the winds I saw on the ground. It's actually based on calculations using the cyclone's dimensions (wind radii), environmental and peripheral pressure values, and climatological means (for pressure/wind relationship and RMW). I'll post that analysis here if I get some affirmative feedback from a more authoritative source. (I don't want to post it unless it's deemed to be sound methodologically.)

* Whatever Jova's landfall intensity, the winds would have been lower at our location (the center of a town a couple of mi inland) for the usual reasons. Only a tiny area over water or right at the open coast-- if anywhere at all-- experiences the "best-track" wind speed when a hurricane makes landfall. For this reason, you can't use this footage to put a ceiling on the cyclone's peak winds. The footage shows that Jova's max winds were at least this strong.

Before I respond to each one of your points directly, please allow me to begin by stating that my original post was meant to simply congratulate you on another successful chase event and one that appears to be one of your best to date, if not the best!

Since many others have offered their own thoughts relative to the maximum winds you might have encountered at your specific intercept location, I thought I would do the same. Likewise, since you and others referenced our hurricane Wilma chase for comparable purposes, I too chose to do the same.

1) Although I suspect you are correct in assuming that the winds you encountered in hurricane (H) Jova were "stronger" than those you experienced in Wilma (as I alluded to in my original post), there are no empirical observations (i.e. wind measurements) available from your intercept location in order to make a definitive and entirely objective assessment. That aside, I am acutely aware that the maximum 1-min. sustained winds (MSW) we encountered in Wilma were likely in the moderate category-one range. That's why I suggested that the MSW you experienced in Jova was likely a little higher than what we experienced during H Wilma. Although I suspect that the MSW you experienced in Jova exceeded that of which we encountered during H Wilma, I'm not as confident that the same holds true for the peak 3-second wind gusts. To be specific, the meteorologist you referenced in your H Wilma chase report estimated that the maximum wind gusts we experienced were likely in the 87-104 knot range (100-120 mph). I know that the 5 m tower located 5 nm to our NE (in Ochopee) recorded peak 3-sec. wind gusts of 84 knots (97 mph), which supports the aforementioned meteorologists estimation. For me, Wilma was unique from many of my other H intercepts in that there was a greater disparity between the MSW and the peak wind gusts I experienced. Furthermore, the peak wind gusts in Wilma weren't as frequent as well, comparatively speaking. In short, I'm not so sure that the wind gusts you experienced in H Jova reached or exceeded the 100 knot range. Then again, I can't say they didn't, either.

2) My reference to all "available meterological data" in my previous post encompassed everything you mentioned in your reply. Naturally, there is no available meteorological data that I have assess to that you don't. That said, there may be some slight differences in how we interpret that data.

3) Like you, I suspect that H Jova may have been a slightly more intense cyclone at landfall. I stated as much in my previous post, as well. However, I have yet to see any objective meterological evidence that suggests that it had reattained its former category-three classification.

4) I apologize for any unintended confusion, but I never meant to suggest that your chase footage should be used to "put a ceiling on the cyclone's peak winds." I am acutely aware of the frictional effects of land and the subsequent decrease of the MSW felt onshore at the land-ocean interface, and points further inland. Although I didn't articulate it as well as I should've, there is still a noticeable difference in the winds you experienced at your specific intercept location (with an elevation of 73 feet above ground level) than what would've been observed at the standard height of 33 feet above ground level.

Based upon the apparent landfalling intensity of H Jova, the proximity of your intercept location to the RMW, the elevated height from which you observed the storm, and the chase footage you've provided, I think it's plausible that the MSW you experienced may have been ~85 knots. Based upon the chase footage alone, the MSW seen in your video seems somewhat comparable to the MSW I observed during H Katrina in south Mississippi. It was at minimal category-two intensity (85 knots) when the RMW passed directly over my intercept location. To date, I have yet to experience wind gusts that exceed those from which I observed on that fateful late August day. The maximum 3-sec. winds were officially estimated by the NWS (based on empirical measurements obtained nearby) to be in the 100-110 knot range. Without being there myself, and due to the limitations of night-time visibility, it's difficult for me to make an accurate estimation of just how comparable the wind gusts shown in your video are to what I experienced during Katrina. All I can surmise is that it appears quite conclusive that the peak 3-sec. wind gusts exceeded 87 knots (100 mph).

Most importantly, I want to conclude by commending you once again for capturing such fantastic footage from your H Jova chase expedition!

[HurricaneJosh]

Before I respond to each one of your points directly, please allow me to begin by stating that my original post was meant to simply congratulate you on another successful chase event and one that appears to be one of your best to date, if not the best. Since many others have offered their own thoughts relative to the maximum winds you might have encountered at your specific intercept location, I thought I would do the same. Likewise, since you and others referenced our hurricane Wilma chase for comparable purposes, I too chose to do the same.

1) Although I suspect you are correct in assuming that the winds you encountered in hurricane (H) Jova were "stronger" than those you experienced in Wilma (as I alluded to in my original post), there are no empirical observations (i.e. wind measurements) available from your intercept location in order to make a definitive and entirely objective assessment. That aside, I am acutely aware that the maximum 1-min. sustained winds (MSW) we encountered in Wilma were likely in the moderate category-one range. That's why I suggested that the MSW you experienced in Jova was likely a little higher than what we experienced during H Wilma. Although I suspect that the MSW you experienced in Jova exceeded that of which we encountered during H Wilma, I'm not as confident that the same holds true for the peak 3-second wind gusts. To be specific, the meteorologist you referenced in your H Wilma chase report estimated that the maximum wind gusts we experienced were likely in the 87-104 knot range (100-120 mph). I know that the 5 m tower located 5 nm to our NE (in Ochopee) recorded peak 3-sec. wind gusts of 84 knots (97 mph), which supports the aforementioned meteorologists estimation. For me, Wilma was unique from many of my other H intercepts in that there was a greater disparity between the MSW and the peak wind gusts I experienced. Furthermore, the peak wind gusts in Wilma weren't as frequent as well, comparatively speaking.

2) My reference to all "available meterological data" in my previous post encompassed everything you mentioned in your reply. Naturally, there is no available meteorological data that I have assess to that you don't. That said, there may be some slight differences in how we interpret that data.

3) Like you, I suspect that H Jova may have been a slightly more intense cyclone at landfall. I stated as much in my previous post, as well. However, I have yet to see any objective meterological evidence that suggests that it had reattained its former category-three classification.

4) I apologize for any unintended confusion, but I never meant to suggest that your chase footage should be used to "put a ceiling on the cyclone's peak winds." I am acutely aware of the frictional effects of land and the subsequent decrease of the MSW felt onshore at the land-ocean interface, and points further inland. Although I didn't articulate it as well as I should've, there is still a noticeable difference in the winds you experienced at your specific intercept location (with an elevation of 73 feet above ground level) than what would've been observed at the standard height of 33 feet above ground level.

Based upon the apparent landfalling intensity of H Jova, the proximity of your intercept location to the RMW, the elevated height from which you observed the storm, and the chase footage you've provided, I think it's plausible that the MSW you experienced may have been ~85 knots. Based upon the chase footage alone, the MSW seen in your video seems somewhat comparable to the MSW I observed during H Katrina in south Mississippi. It was at minimal category-two intensity (85 knots) when the RMW passed directly over my intercept location. To date, I have yet to experience wind gusts that exceed those from which I observed on that fateful late August day. The maximum 3-sec. winds were officially estimated by the NWS (based on empirical measurements obtained nearby) to be in the 100-110 knot range. Without being there myself, and due to the limitations of night-time visibility, it's difficult for me to make an accurate estimation of just how comparable the wind gusts shown in your video are to what I experienced during Katrina. All I can surmise is that it appears quite conclusive that the peak 3-sec. wind gusts exceeded 87 knots (100 mph).

Most importantly, I want to conclude by commending you once again for capturing such fantastic footage from your H Jova chase expedition!

Thanks for sharing your thoughts.

As you said, it would be hard for you to make an accurate assessment of Jova's winds-- and that's OK. My original estimate-- earlier in this thread-- was peak gusts of ~100 kt at my location. So I guess we see it the same way, anyway. Either way, as you said, we'll never know which hurricane-- Wilma or Jova-- produced stronger winds at my location. But having experienced both, I'm pretty sure it was Jova.

Again, my estimate of the landfall intensity is an entirely separate topic-- not in any way related to how strong the winds felt at my location.

One important thing to set straight: I was not 73 ft above the ground. I was at ground level, 73 ft above sea level! See aslkahuna's post, above-- height above sea level and height above the ground are two different things, and I think you're confusing them. The winds in the video are at the surface-- actually, they're below 10 m.

[ncforecaster89]

A minor point perhaps, but when we talk about 1 min winds at 10m, we are talking about 10m AGL not MSL.

Steve

Thank you Steve for catching that inadvertent mistake. It's a very valid point to clarify.

~Tony

[ncforecaster89]

Thanks for sharing your thoughts.

As you said, it would be hard for you to make an accurate assessment of Jova's winds-- and that's OK. My original estimate-- earlier in this thread-- was peak gusts of ~100 kt at my location. So I guess we see it the same way, anyway. Either way, as you said, we'll never know which hurricane-- Wilma or Jova-- produced stronger winds at my location. But having experienced both, I'm pretty sure it was Jova.

Again, my estimate of the landfall intensity is an entirely separate topic-- not in any way related to how strong the winds felt at my location.

One important thing to set straight: I was not 73 ft above the ground. I was at ground level, 73 ft above sea level! See aslkahuna's post, above-- height above sea level and height above the ground are two different things, and I think you're confusing them. The winds in the video are at the surface-- actually, they're below 10 m.

You are absolutely right in that I have been thinking all along that you were positioned 73 feet above ground level, as opposed to sea level. Thank you for clarifying that for me.

As you noted, it appears that we are in general agreement as to the likely intensity of the maximum winds you experienced at your intercept location-which were very impressive!

Once again, great job of positioning yourself so well and capturing such fantastic footage!

~Tony

[HurricaneJosh]

You are absolutely right in that I have been thinking all along that you were positioned 73 feet above ground level, as opposed to sea level. Thank you for clarifying that for me.

Yeah, I wasn't in a high-rise building or a tower-- I was outside, on the side of the highway.

As you noted, it appears that we are in general agreement as to the likely intensity of the maximum winds you experienced at your intercept location-which were very impressive!

Once again, great job of positioning yourself so well and capturing such fantastic footage!

~Tony

Thanks, Tony. I really appreciate it, and I'm glad you enjoyed the video.

[ORH_wxman]

I just watched the full video you posted on Nov 4 (been busy with icep*** stuff you know)....absolutely phenomenal. That is just awesome. It is definitely a lot more impressive than so many of the other videos you have that are cat 2s and even cat 3s. You seemed to jackpot this storm's location.

[HurricaneJosh]

I just watched the full video you posted on Nov 4 (been busy with icep*** stuff you know)....absolutely phenomenal. That is just awesome. It is definitely a lot more impressive than so many of the other videos you have that are cat 2s and even cat 3s. You seemed to jackpot this storm's location.

Hey, thanks, Will-- glad you dug it so much! Cool.

I'm going to a storm chasers' gathering in December, and I think I'm going to bring this as my portfolio piece to share-- since it's recent and it's definitely one of my better catches, footage-wise.

I'm still surprised by it-- just was not expecting to get so raked when we were driving up there that night...

[HurricaneJosh]

As I mentioned above, Jova was quite a bit more violent than Jim and I expected-- and much worse than any other Cat 2 I've been in. See my chase video, which shows particularly severe conditions starting around 4:25:

This unexpected severity sparked my curiosity and drove me to investigate the landfall intensity. Applying the reanalysis techniques that are being applied to historical North Atlantic cyclones, I did an analysis for Jova that yields a landfall intensity of 95-100 kt-- either a strong Cat 2 or low-end Cat 3. (See the attached document.)

For the record, I ran this by one of the reanalysis experts who works under Chris Landsea, and he didn't agree with it-- felt that some of the critical starting values (specifically, the RMW and my distance from the center) were artificially precise. I also discussed it with Jack Beven at a storm chasers' gathering in Florida last week. While he didn't specifically review my analysis, he emphasized that the Dvorak estimates (85 and 90 kt) will take precedence in the post-analysis, and any major upgrade from the operational estimate (85 kt) is highly unlikely without hard wind data to support it.

The NHC is the gold standard for intensity estimates and I defer to them-- they know best, obviously. This having been said, I still wanted to share my analysis. I'll invite the above-mentioned people to this discussion, should they wish to critique this work in greater detail. (Even if they want to demolish this analysis, I'd still consider it awesome to have their participation here. )

Important Note: To head-off any misunderstandings, I am not suggesting Jim and I saw sustained 95-100-kt winds at our location. Even if Jova was a 100-kt hurricane at landfall, we wouldn't see sustained winds that high where we were-- a couple of miles inland, in a town (i.e., not open exposure), and possibly a shade outside of the RMW. I do, however, think we saw sustained winds well over hurricane force, with gusts exceeding 100 kt.

iCyclone Intensity Analysis - JOVA 2011.pdf

[am19psu]

[aslkahuna]

Certainly, you did see gusts in the 100kt+ range-however, remember that over water the ration of sustained to gusts is 1.25 yielding peak gusts of 105kt. JTWC who did the study that yielded the gust ratio in the 1970's also noted at the time that the gust ratio for locations inland could be as high as 1.50-1.60 which would mean lower sustained with the high gusts which is what is seen. You were very close to the water so the lower ratio would probably still be operative. With 85kt sustained therefore you would see gusts to 120 mph and with 90 kt you would have seen 10 mph higher gusts. So it depends upon what you consider your peak gusts.

Steve

[HurricaneJosh]

Certainly, you did see gusts in the 100kt+ range-however, remember that over water the ration of sustained to gusts is 1.25 yielding peak gusts of 105kt. JTWC who did the study that yielded the gust ratio in the 1970's also noted at the time that the gust ratio for locations inland could be as high as 1.50-1.60 which would mean lower sustained with the high gusts which is what is seen. You were very close to the water so the lower ratio would probably still be operative. With 85kt sustained therefore you would see gusts to 120 mph and with 90 kt you would have seen 10 mph higher gusts. So it depends upon what you consider your peak gusts.

Steve

Hey, Steve!

So you're saying that we would have had a gust ratio near 1.25, since we were pretty close to the water? That makes sense.

But one thing I should point out: we were a couple of miles inland, in a town-- i.e., not right on the coast with open marine exposure. Whenever I look at the HRD's surface wind (H*WIND) analyses, I notice that the analyzed wind speeds drop off precipitously once you get away from the immediate, open coast. Given this, I wouldn't expect that we'd see the actual "best-track" wind speed at our location, but instead, something a good 10-20 kt lower. Do you think that's a reasonable assumption?

[ncforecaster89]

February 6: NHC cyclone report on Hurricane Jova released.

Landfall intensity confirmed to be 85 knots (98 mph),

http://www.nhc.noaa....102011_Jova.pdf

[HurricaneJosh]

Landfall intensity confirmed to be 85 knots (98 mph),

For intensities in HURDAT, 85 kt = 100 mph (not 98 mph). Estimates aren't made to the nearest 1 mph. The science isn't there for that level of precision.

P.S. But if you're fixated on precision, you should have said the landfall intensity was 97.8162531 mph.

[HurricaneJosh]

A very weird storm. It put every other Cat 2 and Cat 3 I've chased in recent years to shame. It seemed much more violent than ones like Gustav 2008 (in Louisiana) and Karl 2010 (near Veracruz) that had higher landfall-intensity estimates.

Too bad there weren't any recon data and too bad the Cuyutlan radar was down. That only left satellite-derived estimates-- as described in the report:

The 85-kt intensity estimate for Jova at landfall is based on a blend of a 90-kt Dvorak intensity estimate from TAFB and a 3-h average ADT intensity of 77 kt at 0600 UTC 12 October.

So they just didn't have much to work with.

If anyone can find footage like this from another low-end Cat 2, let me know.

[wxmx]

[HurricaneJosh]

Anyhoo, the report cites my pressure reading near the landfall point, which I'm pleased about.

[ncforecaster89]

For intensities in HURDAT, 85 kt = 100 mph (not 98 mph). Estimates aren't made to the nearest 1 mph. The science isn't there for that level of precision.

P.S. But if you're fixated on precision, you should have said the landfall intensity was 97.8162531 mph.

Hey Josh,

The previous post was in no way meant to disparage your belief that "Jova" may have been a more intense tropical cyclone, when it crossed the Mexican shoreline. In fact, I am inclined to favor the 90 Kt. satellite intensity estimate over the current NHC ascribed intensity, myself.

Although "Jova's" landfalling intensity may reasonably be left open to some genuine debate, I would suspect that very few persons would say the same about the footage you obtained from that particular chase-for it was very impressive!

[HurricaneJosh]

Hey Josh,

The previous post was in no way meant to disparage your belief that "Jova" may have been a more intense tropical cyclone, when it crossed the Mexican shoreline. In fact, I am inclined to favor the 90 Kt. satellite intensity estimate over the current NHC ascribed intensity, myself.

Although "Jova's" landfalling intensity may reasonably be left open to some genuine debate, I would suspect that very few persons would say the same about the footage you obtained from that particular chase-for it was very impressive!

Thanks, Tony-- I really appreciate that.

Re: the landfall-intensity verdict... I understand where the NHC is coming from and, anyhoo, I just have to accept it-- as hard as that is. Ninety knots would have been nicer-- but, oh well.