BBC Weather

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Graeme
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BBC Weather

Post by Graeme »

Hoping the BBC Weather site has a glitch:

Screenshot 2024-10-10 110534_EL.jpg
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GeoffW
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Re: BBC Weather

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Leif
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Re: BBC Weather

Post by Leif »

Graeme wrote:
10 Oct 2024, 10:09
Hoping the BBC Weather site has a glitch:
Pah! My local forecast shows a wind speed of 15,505mph...
Leif

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ChrisGreaves
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Re: BBC Weather

Post by ChrisGreaves »

Graeme wrote:
10 Oct 2024, 10:09
Hoping the BBC Weather site has a glitch:
Maybe not.
In this post I documented the wind dropping to an apparent zero in terms of speed and gust-speed
"The wind has died away completely in the space of fifteen minutes. A glance out of my bedroom window tells me that the tops of my trees are not moving at all"
:sneaky: We should expect zero-speed winds whenever the eye of a low-pressure system crosses over us, where "over" is probably at least a one-mile-wide strip of land.

At its narrowest point (Tampa-Melbourne) Florida is about 200 Km wide, so we can use that as a first-estimate of the length of the path of Milton across Florida.
The area of Florida is (say) 170,000 km2
The population of Florida is (say) 23,000,000
The average density of population would then be 135 people per square kilometre.
Assuming a zero-wind track 2 Km wide, some 54,000+ people in Florida would experience zero-speed winds as a hurricane crossed the peninsula.

A similar calculation could be presented for any low-pressure system crossing your sceptred isle.

Mind you, were I modelling such behaviour I would include factors such as:-
(1) Seasonal adjustments as (in Florida) snowbirds boost the population for two to four months.
(2) The range of wind-speeds considered to be “at zero”, which will thus determine the width of the track
(3) The speed of passage of the eye of the storm, since a slower-moving eye will harvest more mobile populations – cars bearing passengers traveling across or through the eye of the storm.
(4) Incremental local variations in density. Tampa and Melbourne have populations that are quite dense, whereas swampy country such as that around Florence Villa and lake Hamilton could well have populations that are much more dense
(5) The intensity of the low-pressure system; intense storms will generate voluntary and involuntary evacuation, temporarily lowering the population density BUT increasing the track-width. There’s probably a PhD in there somewhere for some lucky graduate.

Cheers, Chris
(2)This wasn't a footnote reference, and you knew it!
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PJ_in_FL
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Re: BBC Weather

Post by PJ_in_FL »

Friends, we were extremely fortunate the hurricane trended southward in the hours before landfall. Our house experienced TS level winds and moderate rain. We never lost power according to my front porch security camera. :fanfare:

I fear for the areas that experienced the tornados, with over 30 reports, mostly on the Atlantic side of the state. Some co-workers on my WhatsApp group had reports of tornados near and around them. I'm waiting to hear back to see if they are safe.

Wife's sister, nephew and family stayed with us over night in Orlando, fleeing the storm from Coquina Key and Largo. Wife, nephew and niece-in-law went for a walk last evening, finding the 40+ MPH winds to be lots of fun.
:hairout: :scratch:

I declined due to the prospect of going down 5 flight and back up on bad knees being not something I wanted to face. I'll venture out when the elevators are restarted.

Until then I'm happy to sit in my PJs and experience the world from the 6th floor screened porch.
PJ in (usually sunny) FL

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HansV
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Re: BBC Weather

Post by HansV »

Glad you're OK. Let's wish for the best for others.
Best wishes,
Hans

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ChrisGreaves
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Re: BBC Weather

Post by ChrisGreaves »

PJ_in_FL wrote:
10 Oct 2024, 12:09
I declined due to the prospect of going down 5 flight and back up on bad knees being not something I wanted to face. I'll venture out when the elevators are restarted.
This is good news for me, as I've been wanting to ask you for a while about the plywood sheeting over windows, and your comment suggests that you have oodles of time to sit at the computer with a coffee or tea and indulge me in my insatiable curiosity.

World-wide, the news media show images of one or two guys on a ladder fastening sheets of plywood (or similar) across their house windows.

At first glance that makes sense to us all, but me, I start wondering ... The energy in a moving fluid (e.g. air) is proportional to the cube of the velocity, so a 75 mph wind gust carries 27 times as much energy as a regular daily wind-gust of 25 mph.

This suggests that one needs to drive in more than a handful of two-inch wood-screws for each 8'x4' sheet of wood. Or even twist washers and nuts onto 1/4" bolts embedded in the outside walls, or what have you.
It seems that it would be an all-day job for two guys to haul the sheets out of the barn and fix 'em on; and another day for two guys to unfix 'em and stack them back in the barn.
Two neighbours helping each other would invest for man-days on a hurricane, yes?

An alternative is to leave all doors and windows open to avoid the house exploding due to a rapid drop in air pressure. But then the drapes would be shredded and the harpsichord left out of tune.

An apartment building, say 25 storeys high with twelve condominiums on each floor, how do they secure the windows?

And I would have asked about factories and warehouses, but nowadays they all seem to be window-less.

By the time you reply to this and grab another :co9ffee: I'll probably have more questions ...
Thanks,Chris
If it isn't one thing it's another, and very often both. E.F.Benson

PJ_in_FL
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Re: BBC Weather

Post by PJ_in_FL »

I replaced all windows last year with "hurricane proof" windows. Luckily they didn't get tested.

I didn't put up any plywood for that reason and the forecast was for a CAT 1, not CAT 5.

My sheets go in with clips that dig into the concrete around the windows. As long as the plywood is tight to keep the wind from getting behind it, the sheets will stay in place. Pressing the clips in is all that's needed to remove the sheets after the weather returns to normal. A little paint touch up and we're good to go.
PJ in (usually sunny) FL

PJ_in_FL
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Re: BBC Weather

Post by PJ_in_FL »

ChrisGreaves wrote:
10 Oct 2024, 12:33
...
An alternative is to leave all doors and windows open to avoid the house exploding due to a rapid drop in air pressure. But then the drapes would be shredded and the harpsichord left out of tune.
...
I think that's more for tornados. Hurricanes don't have that rapid pressure drop, just strong, sustained winds. Those winds cause the most damage from hurricanes away from the coast. Tropicana Field lost it's roof, and it was a staging area for 10,000 power linemen. Guess that didn't work out as well as they hoped.
ChrisGreaves wrote:
10 Oct 2024, 12:33
...
An apartment building, say 25 storeys high with twelve condominiums on each floor, how do they secure the windows?

And I would have asked about factories and warehouses, but nowadays they all seem to be window-less.
...
Never saw any condos with boarded windows. Some first floor businesses had drop down covers over their windows.

As for factories, one in north St. Petersburg I was in the week following Helene still had shutters over the front windows where offices and conference rooms were. As you suggested, very few windows around the building's production area. And the many new distributions centers I see popping up almost as fast as Dollar General stores have almost no windows that I can see. Just lines of loading dock doors.
PJ in (usually sunny) FL