iCyclone Chase Reports: 2010

[HurricaneJosh]

This year, I started sending chase reports to the NHC so they can use the obs in their Tropical Cyclone Reports. Here are the reports for my Alex and Karl chases:

iCyclone Chase Report - ALEX 2010.pdf

iCyclone Chase Report - KARL 2010.pdf

Jack Beven at the NHC had some really cool and interesting feedback Re: my Karl report-- especially with regard to the striking pressure dips that coincided with damaging winds on the cyclone's backside (quoted with his permission):

I've forwarded your report on to Stacy Stewart, who is writing the Tropical Cyclone Report on Karl.

It's a pity your anemometer wasn't working. On the last four fixes, the strongest winds that the aircraft was seeing at the surface were in the southeastern quadrant of the eyewall. If the SFMR winds were correct, they would have made landfall very close to your position.

From the winds and pressures you describe, especially that last dip associated with a sudden increase in the winds, I'm wondering if you got hit by an eyewall mesovortex (or maybe more than one). I'll have to see if any were visible in the radar data.

The aircraft data suggests there was about 10-15 mb of pressure difference between the center of the eye and the radius of maximum winds, although instrument problems make this a bit uncertain in the southeastern quadrant. This suggests your pressures are reasonable, if possibly a few mb to low as you pointed out.

Thanks for passing this along to us. Keep up the good work, and be careful when you go out chasing!

For easy reference, here are my video teasers for both chases:

[k***]

it's one thing to contribute to the board's collective cyclone voyeurism with chase threads, it's quite another to be actively contributing to the history and science of the field with useful observations that would have gone undocumented absent your involvement. kudos for being the planet's best chaser.

<back to my lair>

[Srain]

I see you've been busy. Finally, we have a record for Americanwx.

[Ian]

cool stuff josh

[Mallow]

[Sickman]

Great job, bro!

[NCHurricane]

Awesome!

[phil882]

This is awesome Josh! Its these things that separate the folks that are there just there for the fame and adrenaline, and the ones who really actually want to make a contribution to the science of meteorology. Who knows... maybe some of obs will go into the Tropical Cyclone Report!

[aslkahuna]

In 1992, I sent a complete report on Tropical Storm Lester to our HQ figuring that they would forward it. However, the US Army's policy for met data gathered by their teams is different than the USAF or Navy so it never was. Hence the official record on Lester is not quite complete and in fact they probably would have upped the 24/06Z Aug 92 advisory intensity from 35 to possibly 40 or 45 kt had they received my report.

Steve

[LocoAko]

Great stuff!!

[HurricaneJosh]

Omg, thanks, everyone for the kind words. I am really flattered. And thanks, Ian, for pinning this-- I was surprised.

:wub:it's one thing to contribute to the board's collective cyclone voyeurism with chase threads, it's quite another to be actively contributing to the history and science of the field with useful observations that would have gone undocumented absent your involvement. kudos for being the planet's best chaser.<back to my lair>

Omg, stop.

Thanks, man-- that's really nice of you to say that.

This is awesome Josh! Its these things that separate the folks that are there just there for the fame and adrenaline, and the ones who really actually want to make a contribution to the science of meteorology. Who knows... maybe some of obs will go into the Tropical Cyclone Report!

Yeah, it feels good to add this reporting dimension; it seems to somehow gives the chasing a little more purpose, so it's not pure thrill-seeking (which I will admit remains the primary motivation). I'm honestly just excited that the NHC is even interested in my obs.

In 1992, I sent a complete report on Tropical Storm Lester to our HQ figuring that they would forward it. However, the US Army's policy for met data gathered by their teams is different than the USAF or Navy so it never was. Hence the official record on Lester is not quite complete and in fact they probably would have upped the 24/06Z Aug 92 advisory intensity from 35 to possibly 40 or 45 kt had they received my report.Steve

Wow-- that's a bummer that they didn't use your report-- especially given that you're an actual met (and therefore your obs have added credibility). I wonder if perhaps the culture might be different now, because they've always stricken me as very receptive to chaser reports.

[HurricaneJosh]

P.S. I see the Alex report has been downloaded more than the Karl report-- but I think the Karl report is a little sexier.

[turtlehurricane]

Dude, you're awesome

[turtlehurricane]

BTW, in my opinion, since you were so far inland, I think the wind bursts you observed were from frictional breakdown of the hurricane's flow in the boundary layer. That would generate small-scale vortices (smaller than eyewall mesovortices by a magnitude) that would drop the pressure just as the gusts comes through.

[HurricaneJosh]

Dude, you're awesome

Thanks, Turtle. (Yeah, I'm still gonna call you "Turtle", because that's what you are to me. )

BTW, in my opinion, since you were so far inland, I think the wind bursts you observed were from frictional breakdown of the hurricane's flow in the boundary layer. That would generate small-scale vortices (smaller than eyewall mesovortices by a magnitude) that would drop the pressure just as the gusts comes through.

Very interesting. What would be the rough dimensions of a small-scale vortex vs. a mesovortex?

I've been reviewing the video (see above) again and again starting at 12:20:54-- when that destructive burst occurs with the 2.4-mb pressure dip-- and I can't identify any rotation or twisting motion. All of the debris seems to be blowing in the same general direction-- up the street, away from the viewer. But it's so hard to tell from that limited viewpoint.

[turtlehurricane]

Thanks, Turtle. (Yeah, I'm still gonna call you "Turtle", because that's what you are to me. )

Very interesting. What would be the rough dimensions of a small-scale vortex vs. a mesovortex?

I've been reviewing the video (see above) again and again starting at 12:20:54-- when that destructive burst occurs with the 2.4-mb pressure dip-- and I can't identify any rotation or twisting motion. All of the debris seems to be blowing in the same general direction-- up the street, away from the viewer. But it's so hard to tell from that limited viewpoint.

Looking at the pressure graph for the first time, I take back what I said. Must be a mesovortice in the eyewall, which are fueled by frictional breakdown so it's still kinda relevant I guess. Frank Marks published a Hugo paper recently with similar pressure features in aircraft data.

[HurricaneJosh]

In 1992, I sent a complete report on Tropical Storm Lester to our HQ figuring that they would forward it. However, the US Army's policy for met data gathered by their teams is different than the USAF or Navy so it never was. Hence the official record on Lester is not quite complete and in fact they probably would have upped the 24/06Z Aug 92 advisory intensity from 35 to possibly 40 or 45 kt had they received my report.

Steve

Hey, Steve--

Jack Beven browsed this thread and wanted me to let you know that the NHC would be delighted to see your Lester report if you still have it, as they're interested in any available sources for reanalysis.

[k***]

Hey, Steve--

Jack Beven browsed this thread and wanted me to let you know that the NHC would be delighted to see your Lester report if you still have it, as they're interested in any available sources for reanalysis.

beven is definitely on my hurricane dude allstar team