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Old 01-05-2018, 10:24 AM   #21
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Besides the moon's gravitation and wind, water levels are affected by atmospheric pressure.

That the atmospheric pressure can have so much effect is surprising to me. I mean atmospheric pressure is somewhere around 14 psi (14.696 according to the 'net) and the variation is + or - what, one psi? And water weighs 65 pcf. Yet, a storm surge on top of a high tide...
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Old 01-05-2018, 10:39 AM   #22
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A one inch change in barometric pressure in inches of mercury means about a foot of water. Specific gravity of Hg I think is around 13.

So if barometer drops from 30.1 down to 29.1, could see a foot difference just due to that.

But when B drops that much, there is certainly going to be some wind involved, and that will likely have a larger effect.
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Old 01-05-2018, 10:52 AM   #23
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I'd like to tell you that I'm in Fl and am sympathetic, but I'm stuck in MD with a few business obligations till Sunday. Shoveling snow sucks! At least the trawler is in FL.

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Old 01-05-2018, 10:52 AM   #24
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What I know about a change in barometric pressure is that when it's changing my head feels like I'm coming off of an all night drink fest. 36 hours ago it came on & it's just subsiding today. The theorize some animals have a built in compass to get them where they're going during migration. I've got a built-in barometer. Great. I'd rather have a compass.
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Old 01-05-2018, 04:08 PM   #25
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A one inch change in barometric pressure in inches of mercury means about a foot of water. Specific gravity of Hg I think is around 13.

So if barometer drops from 30.1 down to 29.1, could see a foot difference just due to that.

But when B drops that much, there is certainly going to be some wind involved, and that will likely have a larger effect.
Ski,

Yes, that's what they say, in fact I thing it's closer to 2 feet with an inch and the higher the pressure the lower the tide.

But it doesn't work that way in my neighborhood. We had pretty normal tides most of Dec. and got hit with the extreme low tides this past week. The only striking change when the tides dropped was the temperature dropped. Winds have been high and low and barometric pressure has been between 30.10 and 30.31 for the most part throughout the time frame.

We always get extreme low tides in the winter months, but I can't figure out how to predict it other than cold air, which doesn't make sense.

The tide charts did indicate low tides, but not nearly as low as it is.

Still trying to figure it out....
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