Wilma top sustained winds below 85 mph in Dade, Broward

[Derek Ortt]

I believe that 115KT gust in Stuart, near NPBC, was from a sailbot over the water, where the winds would be expected to be the highest. it is possible that NPBC received similar conditions

[MiamiensisWx]

Ortt, could areas west of Boca Raton and in southern Palm Beach County closer to the Everglades or on the barrier islands in the Boca/Delray/Boynton areas of southeastern Palm Beach County received brief sustained Category Two winds since those two areas (close to the Everglades and on the barrier islands) were more exposed, resulting in less friction?

[Derek Ortt]

if cat 2 winds occurred away from the Lake, it was near the glades and on the barrier islands

[Recurve]

Great discussion.

Think I said above-- I saw bad tree damage, little house damage, and destroyed boats and docks in the Upper Keys. Some people here think it was over 100 mph sustained and 120+ mph gusts. I think it's probably less. Agree with the Mr. Ortt's always-illuminating comments on the data.

There's open water over Florida Bay for SW-W winds, maybe we had no friction effect. But if Broward/Palm Beach barely saw Cat 2, we probably experienced mid-Cat 1. Still it was devastating in some ways, some marinas and businesses and many homes damaged. People are just sure Cat 1 conditions can't be bad.

[Zackiedawg]

A couple of observations, for both sides of the argument over the sustained winds in PB or Broward county...please feel free to correct me if I'm wrong:

First, there is alot of mention of the fact that the damage exceeded what should be possible with Cat 1 winds, therefore some argue that we must have had higher winds than that. But there is nothing contradictory in saying that you suffered 110MPH wind damage during a Cat 1 storm. The storm itself may have delivered sustained Cat 1 winds over your area, but gusts will still reach far higher. It is often these gusts that will produce the damage you see...ripping fences off at the base, projecting wood through tree trunks, etc. Look at the difference of the sustained vs gust winds recorded at any particular station on the NHC report...some of them are 20-25MPH higher on the gusts. So a sustained 85MPH hurricane can still deliver a 110MPH gust which rips down a fence, knocks down a tree, or slams bark through a car bumper...but it doesn't mean the storm is a SUSTAINED cat 2 or 3 storm.

Second...as to the land friction, I am not a scientist or professional, so I cannot intelligently argue this point. However there are other factors that may contribute to higher winds in particular areas versus others. For example, it seems that areas near wide fields, airports, vast parking lots, or other wide-open areas took more damage being exposed to undiluted winds over a long stretch of open land versus homes or structures surrounded by trees, other houses, buildings, etc. Many people's homes were saved from the maximum winds against structural walls because of neighbor's houses, trees, etc which took some of the impact out of the wind. So if your house is on a lake, golf course, or near an airport, it seems likely that the force of the wind striking your house or property may have been stronger than neighboring areas.

Also, areas around high-rise buildings, or in residential areas where the streets may have run parallel with the wind direction, might have allowed winds to 'funnel', which can strongly increase the windspeeed for structures between or at the end of these corridors. Drive down A1A on a windy day and feel the difference in wind between open stretches and passing by an opening between condos and you'll know what I mean. So your location and surroundings should be taken into consideration as to the affect on the winds.

Third...and this is again an unscientific and personal observation...but during Wilma I closely monitored windspeeds on my weather station to try to get an idea of sustained winds and peak gusts. My (unprofessional) anemometer saw sustained cat 2 windstrength for several minutes at a time, numerous times throughout the hurricane...and measured gusts to 112mph before the mount gave up and blew the anemometer down. The front eyewall stayed at or around 84MPH for sustained periods. But the back eye wall produced several minutes at a time measuring between 93 and 102MPH. I had seen gusts shoot up over 100MPH several times, but never for more than a few seconds...but during the worst of the back eyewall the readings exceeded 100MPH and only dropped back to the upper 90s. Finally a stronger gust caused my maximum reading of 112MPH before I lost the anemometer.

Though I can't speak for the entire city, I can say that in my location in central Boca Raton, near the airport, my house experienced long periods of cat 2 winds on my home anemometer, and gusts up to or exceeding 112mph. I am more than willing to admit a large margin of error for a non-scientist with a non-professional instrument...but I just wanted to put in that observation. I think that the area of my home may have been prone to stronger winds due to large open areas to the west and east of me (to the west are golf courses and in my community a lake, tennis courts, and large field across the street from me with no houses in between, and to the east is the postal distribution parking lot, rainroad track, I-95, Boca Raton airport, and FAU campus...providing more than a mile of fairly open, unimpeded landscape for winds). Given the high amount of damage to FAU's large buildings and the hangars at the airport, and a 4-story office building down the street from me which lost its dome roof, it seems like that open space allowed winds to maintain greater strength.

Anyway...thanks for all the observations and scientific analysis. I am a weather nut...but not professional or educated in meteorology. I have self-learned what little I know, and this forum can provide me with plenty of information to learn!

[MiamiensisWx]

A couple of observations, for both sides of the argument over the sustained winds in PB or Broward county...please feel free to correct me if I'm wrong:

First, there is alot of mention of the fact that the damage exceeded what should be possible with Cat 1 winds, therefore some argue that we must have had higher winds than that. But there is nothing contradictory in saying that you suffered 110MPH wind damage during a Cat 1 storm. The storm itself may have delivered sustained Cat 1 winds over your area, but gusts will still reach far higher. It is often these gusts that will produce the damage you see...ripping fences off at the base, projecting wood through tree trunks, etc. Look at the difference of the sustained vs gust winds recorded at any particular station on the NHC report...some of them are 20-25MPH higher on the gusts. So a sustained 85MPH hurricane can still deliver a 110MPH gust which rips down a fence, knocks down a tree, or slams bark through a car bumper...but it doesn't mean the storm is a SUSTAINED cat 2 or 3 storm.

Second...as to the land friction, I am not a scientist or professional, so I cannot intelligently argue this point. However there are other factors that may contribute to higher winds in particular areas versus others. For example, it seems that areas near wide fields, airports, vast parking lots, or other wide-open areas took more damage being exposed to undiluted winds over a long stretch of open land versus homes or structures surrounded by trees, other houses, buildings, etc. Many people's homes were saved from the maximum winds against structural walls because of neighbor's houses, trees, etc which took some of the impact out of the wind. So if your house is on a lake, golf course, or near an airport, it seems likely that the force of the wind striking your house or property may have been stronger than neighboring areas.

Also, areas around high-rise buildings, or in residential areas where the streets may have run parallel with the wind direction, might have allowed winds to 'funnel', which can strongly increase the windspeeed for structures between or at the end of these corridors. Drive down A1A on a windy day and feel the difference in wind between open stretches and passing by an opening between condos and you'll know what I mean. So your location and surroundings should be taken into consideration as to the affect on the winds.

Third...and this is again an unscientific and personal observation...but during Wilma I closely monitored windspeeds on my weather station to try to get an idea of sustained winds and peak gusts. My (unprofessional) anemometer saw sustained cat 2 windstrength for several minutes at a time, numerous times throughout the hurricane...and measured gusts to 112mph before the mount gave up and blew the anemometer down. The front eyewall stayed at or around 84MPH for sustained periods. But the back eye wall produced several minutes at a time measuring between 93 and 102MPH. I had seen gusts shoot up over 100MPH several times, but never for more than a few seconds...but during the worst of the back eyewall the readings exceeded 100MPH and only dropped back to the upper 90s. Finally a stronger gust caused my maximum reading of 112MPH before I lost the anemometer.

Though I can't speak for the entire city, I can say that in my location in central Boca Raton, near the airport, my house experienced long periods of cat 2 winds on my home anemometer, and gusts up to or exceeding 112mph. I am more than willing to admit a large margin of error for a non-scientist with a non-professional instrument...but I just wanted to put in that observation. I think that the area of my home may have been prone to stronger winds due to large open areas to the west and east of me (to the west are golf courses and in my community a lake, tennis courts, and large field across the street from me with no houses in between, and to the east is the postal distribution parking lot, rainroad track, I-95, Boca Raton airport, and FAU campus...providing more than a mile of fairly open, unimpeded landscape for winds). Given the high amount of damage to FAU's large buildings and the hangars at the airport, and a 4-story office building down the street from me which lost its dome roof, it seems like that open space allowed winds to maintain greater strength.

Anyway...thanks for all the observations and scientific analysis. I am a weather nut...but not professional or educated in meteorology. I have self-learned what little I know, and this forum can provide me with plenty of information to learn!

Good points... I am learning as well. My arguments in the Camille thread have been awful... sorry...

[Bocadude85]

Im no expert myself but I rode out Wilma in southwest Boca Raton very near the everglades and what I saw was definately higher then 75-85mph winds,for periods of time the whole house shook and you could hear the glasses in the kitchen cabinets rattling, the garage door blew in and when that occured the side door in the garage blew out ripping the the door and the frame right out of the wall. The only tree left standing in the yard was a large royal palm which had been stripped of all its leaves. The house sits right on a canal and without a doubt there was 5 foot swells going down the canal. The whole neighborhood recieved extensive roof damage, many roofs were stripped right down to the plywood, the damage could have been worse here b/c they were older construction homes, but I believe for a brief time we saw cat 2 conditions.

[Aslkahuna]

For those of you with Davis digital anemometers realize that the sensor samples every three seconds. This means two things-first you need to take 20 consecutive readings (without a break) and take the average of all those readings to get your one minute sustained winds. Secondly, this sampling interval means that you might miss a peak gust of short duration. By using a data logging program and setting to average windspeeds over a one minute interval, then you solve the first issue but unfortunately unless you can reduce the sampling interval you will not solve the second. Finally, taken by itself a 112 mph gust with an overland ratio of 1.4 gives a sustained wind of 80 mph-low end Cat 1 but without knowing if the winds you had on the backside of the eye were onshore/along shore/offshore it's difficult to ascertain what ratio to use. Also the presence of nearby structures, open areas and alignment of streets are things to consider. A hurricane in an urban area is a much different animal wind wise than one over open water or a flat land area such as a Bayou or swamp you are going to get all sorts of eddies, swirls and funneling effects in an urban area that is going to give a very complex wind pattern and some areas may actually experience winds totally out of character for the storm in both ways. At Clark AB, the official wind sensor would routinely read low because it was at the low end of the runway while the Rawin section close to the high end would read 10-20 knots higher. When a storm passed north of us downsloping and funneling off the terrain to our west would result in the housing area receiving much higher winds and more damage than down by the runway complex so there's always a lot to consider when observing the effects of hurricanes.

Steve

[curtadams]

Are all these amateur observations recorded somewhere? Zackiedawg is claiming real Cat 2 conditions on the ground in *Boca Raton* and IMO that's pretty significant for ascertaining the strength of Wilma. I haven't been checking observations carefully but that seems very much stronger than the obs I've seen reported elsewhere. There are credibility issues with amateur observations but data is data.

[Derek Ortt]

often times, home anamometers do not stand up to windtunnel testing

[Zackiedawg]

Aslkahuna,

Thanks for the additional info and observations. I certainly know there are margins of error and inaccuracies in my Davis station, and would never take that as absolute fact of windstrengths in our area. I just thought it was an interesting tidbit to throw in there with other observations, and with this maybe some better estimate of sustained winds can be determined. It is highly unfortunate not only that my anemometer failed during the storm, but that many of the professional and monitored anemometers failed as well (either from wind damage, structural damage, or power failure) resulting in a near-blackout of windspeed results during the storm throughout much of Broward and southern Palm Beach county.

However, I did try to make a best amateur effort in arriving at realistic sustained windspeed measurements from my system by monitoring the readout for much of the storm...and taking readings over several-minute periods at a time. As you mentioned, shorter bursts or lulls may fall within the gaps of the digital system's 3-second update, but it does give a fairly good idea of sustained winds if the digital readouts stayed within a particular range for several minutes at a time, and repeated those strengths several times throughout the storm. Not 100% accurate or reliable scientifically, but certainly showing that winds didn't just touch Cat 2 strength once or twice as an anomaly, but stayed or peaked into that strength over a period of 10-15 minutes. Whether they can truly be determined to be sustained...I guess not without a professional system and a certified monitoring.

Curtadams,

I agree, it is significant. But at the same time, even if my amateur readings were considered within an accurate range of measured sustained winds during the storm, it would still have to be considered minimal, as those Cat 2 sustained windspeeds I saw on my unprofessional station were for several minutes out of several hours worth of storm conditions. Even during the passing of the eye wall, front and back, I measured predominantly Cat 1 winds with a few moments of Cat 2 strength. I am solely basing my sustained estimate on the fact that I observed readings above the Cat 2 threshhold for over 1 minute at a time, several times during the eye wall.

Derek,

That too is true...I have finally gotten the replacement unit for my broken one last week, and have decided to mount it to my fireplace chimney this time, via a small mast. It should be clear of interference from nearby structures, but may give slightly inaccurate readings for winds from the south due to the slope of my roof affecting straight line winds from that direction. But it should prove a stronger mounting base than my front wall, which it pulled free of during Wilma.

I truly doubt the flimsy little plastic cup blades on these little home units could stand up to anything more than Cat 2...and as I found out, sometimes the mount gives up before the device itself, even in Cat 1 winds.

[HurricaneBill]

Derek, what sustained winds did the Bahamas probably receive?

[Tampa Bay Hurricane]

Wilma had some fierce gusts that were stronger than I expected-
that's for sure; cold front energy made the western half stronger
than it would have been....probably added 20-30mph to gust speed
since cold fronts deliver those sorts of winds without a hurricane...

[Derek Ortt]

Looks like the Bahamas had upper 2 or lower 3 winds. In addition, they had a tidal surge approaching 15 feet, which efficiently rearranged much of Grand Bahama Island

[Tampa Bay Hurricane]

Wilma had a very large windfield of tropical storm force
conditions and a pretty large hurricane force condition
windfield...this likely led to more widespread damage across
south FL.

[Recurve]

Im no expert myself but I rode out Wilma in southwest Boca Raton very near the everglades and what I saw was definately higher then 75-85mph winds,for periods of time the whole house shook and you could hear the glasses in the kitchen cabinets rattling, the garage door blew in and when that occured the side door in the garage blew out ripping the the door and the frame right out of the wall. The only tree left standing in the yard was a large royal palm which had been stripped of all its leaves. The house sits right on a canal and without a doubt there was 5 foot swells going down the canal. The whole neighborhood recieved extensive roof damage, many roofs were stripped right down to the plywood, the damage could have been worse here b/c they were older construction homes, but I believe for a brief time we saw cat 2 conditions.

That sounds like isolated anomolous winds, definitely more wind damage than most areas. Too bad that happened in your area.

Looks like the Bahamas had upper 2 or lower 3 winds. In addition, they had a tidal surge approaching 15 feet, which efficiently rearranged much of Grand Bahama Island.

Oh my, managed to miss that info. Not again for those people too.

Wouldn't have thought Grand Bahama would get a strong recurving storm. Wilma gets almost no knockdown from Florida and strengthes right back. These land masses have to start looking out for each other.

[MiamiensisWx]

*BUMP*

[Jim Cantore]

hmm I saw video from Miami it looked like about 100