Some Notes on Hurricane Dennis

[Jack Beven]

I'm sorry I've taken so long to chime in on Dennis, but I've been just a little busy! I also apologize for posting this here, but I'm not currently cleared to post in the Dennis discussion in the Target Area.

I'm the hurricane specialist writing up the post-storm report on Dennis, and I'd be very interested in getting hard data from the chasers that were in the area. I've seen Simon's report of 945 mb in the eye, and I'd like to get some particulars about that, like the exact location and time. The last pressure we got from the reconnaissance aircraft was 946-945 mb just before landfall, so Simon's pressure is at least consistent with that.

A couple of things I've found: The Florida Coastal Monitoring Program had a tower in Navarre which measured 99 mph sustained winds. Comparing the tower location with radar and aircraft data suggests that it didn't measure the maximum winds, which most likely came ashore near the western end of Navarre Beach or in the national seashore just west of there. Pensacola got the western eyewall, with both the airport and the FCMP tower at the airport reporting pressures of about 956 mb.

Any data that you all are able to provide will be most appreciated.

Jack Beven
Tropical Prediction Center

 

[Perry Williams]

Hi Jack!
I'm so glad to see you posting here...

Unfortunately, I was unable to chase hurricane Dennis as it made landfall (due to a loved one in hospice care; since deceased), but hope to be in position to report wx observations the next time a significant hurricane makes landfall along the U.S. SE Atlantic or eastern/ middle Gulf coast.

You might want to also post your inquiry at another wx forum I frequent (Storm2k.org); there are a great many posters from that area of the panhandle....many of whom possess home wx equipment (barometers; anemometers; etc). I agree....it was clear from recon data the peak winds at landfall were confined to a very narrow (5-7 mi) corridor along the beachfronts...between Navarre Bch and Gulf Breeze.

Also, my humble thanks to you and the other hurricane specialists at NHC on a job well done.

Take care,
Perry aka "SouthernWx"

 

[Simon Brewer]

Hi Jack,

My chasepartner Shawn and I were in the town of Pace when the eye passed over us. We had a barometer calibrated for sea level, but our GPS stated we were 30ft above sea level at the time of our measurements. At approxiamately 3:09 pm Central our barometer measured the pressure at 945mb. The pressure held at 945mb unchanging throughout the duration of the eye. At 3:18pm Central the barometer still held at 945mb, but I'll have to go back through my video to find the last measurements in the eye, but I'm pretty certain the pressure held to 945mb to the 3:20-3:21pm time frame. Dark clouds from the SW moved in and the winds picked up and the pressure jumped up to 952mb rather quickly and despite our northward journey to keep up with the center of the hurricane the pressure recorded by the barometer continued to significantly rise through the evening and night.

It's very intersting that Navarre only recorded 956mb, because during the most intense winds our pressure dropped and held at 955mb for quite a few minutes until the eye moved over us, and I literally observed the pressure at 955mb and only as the winds became a light breeze did the pressure drop to 945mb! Then the light breeze became dead-calm with very light sprinkles inside the eye! Just as quickly as the pressure dropped on the North side of the eye the pressure rose on the south side of the eye to 952mb and very shortly after the pressure was up to 965mb. So I'm guessing even if you were ever so close to the eye inside the eyewall you would only have measured around 955mb, but you could have been a few miles away from that and not even measure below 960mb! That was an amazing hurricane despite it's decrease in intensity as it made landfall!

If you need anything else like video or other info I'll be glad to help.

Simon