HRD surface wind analysis maps

[docjoe]

Could someone explain how the HRD develops these maps. I would assume it is from actual windspeed measurements, perhaps radar data, and data from planes in the storm. The reason I ask is this: I live for all practical purposes midway between the head of Escambia Bay and the head of Blackwater/East bay in the panhandle. These maps show higher sustained winds from Ivan in my area than from Dennis (assuming I am interpreting them correctly). However the eyewall of Dennis passed right over us. My personal experience was that Ivan did not produce sustained winds that approached the strength of Dennis. My understanding was that we had sustained Cat 1 with Ivan and high end Cat 2/low Cat 3 with Dennis.The maps do not support this at all. Thanks in advance for the help!!

docjoe

[senorpepr]

Those maps are created with every possible observation that is credible. That includes surface observations, buoys, radar, recon, radar, dropsondes, rawinsondes, anything.

[senorpepr]

From the HRD website:

An HRD wind analysis requires the input of all available surface weather observations (e.g., ships, buoys, coastal platforms, surface aviation reports, reconnaissance aircraft data adjusted to the surface, etc.). Observational data are downloaded on a regular schedule and then processed to fit the analysis framework. This includes the data sent by NOAA P3 and G4 research aircraft during the HRD hurricane field program, including the Step Frequency Microwave Radiometer measurements of surface winds, as well as U.S. Air Force Reserves (AFRES) C-130 reconnaissance aircraft, remotely sensed winds from the polar orbiting SSM/I and ERS, the QuikScat platform and TRMM microwave imager satellites, and GOES cloud drift winds derive from tracking low level near-infrared cloud imagery from these geostationary satellites. These data are composited relative to the storm over a 4-6 hour period. All data are quality controlled and processed to conform to a common framework for height (10 m or 33 feet), exposure (marine or open terrain over land), and averaging period (maximum sustained 1 minute wind speed) using accepted methods from micrometeorology and wind engineering (Powell et al., 1996, Powell and Houston, 1996). This framework is consistent with that used by the National Hurricane Center (NHC), and is readily converted to wind load frameworks used in building codes.

[docjoe]

Thanks for the info. This does lead to my next question...how accurate are they considered to be? While i have no hard data to back my assertion my personal observation is that Dennis had significantly higher sustained winds than Ivan.....just much less duration. Also Dennis hit a coastline that was lacking in measuring equipment. I dont believe that the eyewall passed directly over any measuring device at or after landfall. Could this account for the discrepancy?

docjoe

[senorpepr]

Thanks for the info. This does lead to my next question...how accurate are they considered to be? While i have no hard data to back my assertion my personal observation is that Dennis had significantly higher sustained winds than Ivan.....just much less duration. Also Dennis hit a coastline that was lacking in measuring equipment. I dont believe that the eyewall passed directly over any measuring device at or after landfall. Could this account for the discrepancy?

docjoe

It is rather accurate, although it may be underestimated slightly. Even with the lack of surface observations, there were still plenty of data sources such as radar and recon. That might be enough to slightly underestimate the winds, but not enough to make a vast difference.

[docjoe]

Thank goodness I went into medicine instead of meteorology....medicine is easier and makes more sense!!!!! While I have no doubt what I personally witnessed (significantly higher sustained wind with Dennis) I certainly do not have the knowledge or background to make a reasonable assumption as to the discrepancy. Anecdotal evidence rarely is sufficient to make broad factual statements. Thanks for the help

docjoe

[Derek Ortt]

Pensacola itself received the western eye wall from Dennis. The cat 3 winds, thankfully passed east of the city, though residents of the Milton and Navarre Beach areas will not be thankful for that

[docjoe]

Pensacola itself received the western eye wall from Dennis. The cat 3 winds, thankfully passed east of the city, though residents of the Milton and Navarre Beach areas will not be thankful for that

I live on the west side of Milton . Without a doubt we got the eyewall. It was quite a day albeit thankfully short.

docjoe

[hurricanetrack]

What a difference a few tens of miles can make. I was on the west side of Dennis- just outside of the core- and had a 5 meter anemometer (well, the tower was 5 meters) set up at Perdido Key- right in the fire dept. parking lot. Exposure to the wind was as good as it gets. Yet, all I recorded the entire afternoon was a 54 mph gust. This was on an RM Young anemometer- one of the best out there. I wish so badly that I had read the radar closer and saw that Dennis was NOT going to railroad Gulf Shores as we all thought it would as late as 5 am THAT morning.

I was able to drive my Tahoe around with no trouble. Yet, just 30 miles or so east of me all hell was breaking loose.

Now- contrast that to Katrina. Its eye came in at the LA/MS border and 90 to 130 miles east all hell was breaking loose. A great example of the size of the hurricane force wind area.

Just another example of how 2005 will certainly live in infamy- hurricane-wise.

[tailgater]

I'd like to add to that by saying, a squall line on top of you can may a great deal of difference also ( Katrina's center was ENE of our home by about 65 miles when we got her worst in our area @ 70 mph bring down several 200 year old oaks and knocking the tops out of lots more.

[Hybridstorm_November2001]

Indeed:


http://docs.lib.noaa.gov/rescue/mwr/092 ... 7-0353.pdf

[docjoe]

I'd like to add to that by saying, a squall line on top of you can may a great deal of difference also ( Katrina's center was ENE of our home by about 65 miles when we got her worst in our area @ 70 mph bring down several 200 year old oaks and knocking the tops out of lots more.

I do remember we had a squall come through 24 hours before Dennis made landfall. It was hot and humid and then clouded up very quickly. Rained to beat the band for about 10-15 minutes with some probably tropical storm force gusts then back to bright sunshine. The rest of the day was beautiful and fairly calm.

docjoe

[MGC]

I have issues with the Katrina wind field the HRD produced. The HRD has the highest winds over towards Biloxi area, yet looking at the wind damage yields a different story. Since most all of the wind measuring instruments failed well before landfall, HDR relied primarily on doppler radar from Mobile I think to establish the wind field. Now I'm not quite as high tech as the folks at HRD, I don't have a PHD so my opinion don't mean much. But, like I have posted before, why is the most significant wind damage in the western Harrison County and Hancock County areas? I was over at exit 13 off I-10 just west of Diamondhead the other day and noticed all of the light poles for that exit were blown down by Katrina's east wind. All the light polls were pointed west on the ground. While down the road toward Gulfport, exit 34 has the identical light polls which are all standing. But, the HRD claims a stronger wind existed over exit 34 than over exit 13. So, why then are all the light polls blown down at exit 13? Sorry, but old MGC don't buy into HRD wind field estimates. There are many other examples I can site to reinforce my claims.......MGC

[Ixolib]

I have issues with the Katrina wind field the HRD produced. The HRD has the highest winds over towards Biloxi area, yet looking at the wind damage yields a different story. Since most all of the wind measuring instruments failed well before landfall, HDR relied primarily on doppler radar from Mobile I think to establish the wind field. Now I'm not quite as high tech as the folks at HRD, I don't have a PHD so my opinion don't mean much. But, like I have posted before, why is the most significant wind damage in the western Harrison County and Hancock County areas? I was over at exit 13 off I-10 just west of Diamondhead the other day and noticed all of the light poles for that exit were blown down by Katrina's east wind. All the light polls were pointed west on the ground. While down the road toward Gulfport, exit 34 has the identical light polls which are all standing. But, the HRD claims a stronger wind existed over exit 34 than over exit 13. So, why then are all the light polls blown down at exit 13? Sorry, but old MGC don't buy into HRD wind field estimates. There are many other examples I can site to reinforce my claims.......MGC

Yep - I tend to agree with you there. We stayed here in the house in Katrina just south of the Bay in Biloxi. Throughout the storm, I kept telling the family the "the wind just doesn't seem that bad". And even now, 6 months later, I still say the winds in Katrina - here in east-central Biloxi - just weren't that extreme. I recall stronger and more consistent winds in both Elena AND Georges, not to mention Camille.

Given that setup, I too can't put much credibility into the HRD product... Unless, of course, it's based on gusts - which at times were rather extreme...

[ROCK]

I have issues with the Katrina wind field the HRD produced. The HRD has the highest winds over towards Biloxi area, yet looking at the wind damage yields a different story. Since most all of the wind measuring instruments failed well before landfall, HDR relied primarily on doppler radar from Mobile I think to establish the wind field. Now I'm not quite as high tech as the folks at HRD, I don't have a PHD so my opinion don't mean much. But, like I have posted before, why is the most significant wind damage in the western Harrison County and Hancock County areas? I was over at exit 13 off I-10 just west of Diamondhead the other day and noticed all of the light poles for that exit were blown down by Katrina's east wind. All the light polls were pointed west on the ground. While down the road toward Gulfport, exit 34 has the identical light polls which are all standing. But, the HRD claims a stronger wind existed over exit 34 than over exit 13. So, why then are all the light polls blown down at exit 13? Sorry, but old MGC don't buy into HRD wind field estimates. There are many other examples I can site to reinforce my claims.......MGC

could have been gusts or the never seen / rain wrapped F0-F1.

[MGC]

If it was the invisible rain wrapped tornado then there must have been a zillion of them...Nope, HRD has it wrong......MGC

[ROCK]

If it was the invisible rain wrapped tornado then there must have been a zillion of them...Nope, HRD has it wrong......MGC

So who has it right? Eyewitness accounts? I only ask because HRD analysis are backed by many METS. I am sure a lot of sound data and time was used in its conception.

Not to bring up an old low end 3 storm but Alicia had numerous tornados within its eastern eyewall. This was evident by the tree damage saw along I-45 Clear Creek area.

[docjoe]

If it was the invisible rain wrapped tornado then there must have been a zillion of them...Nope, HRD has it wrong......MGC

I understand where you are coming from. I dont have the technical knowldege to explain the HRD maps for Ivan and Dennis but I do know what I experienced does not correlate all that well with them. Despite that I do feel they can help give one a better understanding of the widespread impacts of a TC.

docjoe

[dhweather]

Those maps are created with every possible observation that is credible. That includes surface observations, buoys, radar, recon, radar, dropsondes, rawinsondes, anything.

Do chickens with their feathers blown off count?

[wxman57]

Do chickens with their feathers blown off count?

Yeah, I think they've done some research on that up at Texas Tech in Lubbock.