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Bill O
12-07-2006, 01:44 PM
Does anybody have a good reason why Mount Washington reports their actual station pressure to the public? Opposed to adjusting to sea level.

As a meteorologist knowing the actual pressure (typically 23-24 inches of mercury at MWO) is invaluable. It lets you know just where the summit sits in the atmosphere and vice versa.

Now, for the general public this is quite possibly the most useless piece of data. Mount Washington is probably only one of a handful of sites in the world that does not adjust to sea level.

One thing that might be cool is to convert their pressure into a physio-altitude. Which would show how high Mount Washington feels compared to the standard atmosphere. During strong storms the summit may have a physio-altitude over 7,000 feet...take that Mount Mitchell.

I'm not looking to stir any controversy, just a friendly debate.

tkahike
12-14-2006, 01:49 AM
For me, I'd rather have the actual then adjust it myself. Living so far away it doesn't matter to me what the ground is, I'd rather have the summit since that is my interest. Otherwise I don't know.

AlpineHikerFan71
12-14-2006, 10:16 AM
I dont live all that far away from the summit, but the climate here is very different by 100 miles or so , I would rather have the actual summit data myself. I like to see what 100 miles and topography can do to the weather and how much it changes or as a few weeks ago during the inversion that was going on up there it was cooler here in the morning than on the summit

Bill O
12-14-2006, 10:24 AM
I dont live all that far away from the summit, but the climate here is very different by 100 miles or so , I would rather have the actual summit data myself. I like to see what 100 miles and topography can do to the weather and how much it changes or as a few weeks ago during the inversion that was going on up there it was cooler here in the morning than on the summit

I think my point has been largely mis-interpreted here. By looking at the actual station pressure (around 23.00 inHg) you have no reference point. You are simply looking at the height of Mount Washington not the weather. Unless pressure is adjusted to sea level you cannot compare them.

I was hoping some of the other meteorologists would chime in here, this is not beginner level material.

Bill O
12-14-2006, 10:28 AM
For me, I'd rather have the actual then adjust it myself. Living so far away it doesn't matter to me what the ground is, I'd rather have the summit since that is my interest. Otherwise I don't know.

Please elaborate. What is useful about knowing that the pressure on Mount Washington this morning was 23.65"? It tells you nothing about the weather, just that Mount Washington is high.

The fact of the matter is that all other weather stations in the country convert their pressure to sea level even though none of them are located at sea-level. This is the only logical way, its how you compare apples to apples. If you don't convert to sea level all you are seeing is altitude, not weather data.

tkahike
12-15-2006, 12:46 AM
I am only curious about the weather at the summit, that is where my interest lies. I'm not comparing it to anywhere else, just the summit. Maybe I'm looking at wrong?

Mike D
12-15-2006, 11:39 AM
Bill, as a meteorologist, do you think the sea-level adjusted pressure atop Mt Wash is much different than that of North Conway or Whitefield?

I think you're advocating a more human-relevant piece of data, which is valid. However, compare pressure to wind speed; both are artificially changed by the topography of Mount Washington in ways that don't affect regular people. In that case, would a sea-level adjusted wind speed be a better statistic to report? I think it would be wicked boring.

Bill O
12-15-2006, 12:39 PM
Bill, as a meteorologist, do you think the sea-level adjusted pressure atop Mt Wash is much different than that of North Conway or Whitefield?

Theoretically, it would be right in between North Conway and Whitefield. But in practice I still think it would be different. For one, Mount Washington is shaped much like the top of a wing, so that would induce lower pressures during strong winds, even after adjustment to sea level. Also, the summit often sits in an entirely different air mass than the valleys so that would also create a difference.

This brings up an interesting point because adjusting to sea level pressure is not a perfect science, and its particularly inaccurate for mountain tops.

With caveats, I stick by my original arguments. Mount Washington is the only weather station I know that regularly reports pure station pressure to the public. If you don't regularly look at the station pressure it can hard to interpret. That's why everyone else converts to a common altitude.

Doyle
12-30-2006, 10:45 PM
I have to agree with Bill, We all know the altitude of Mt Washington. We are all really interested in the weather not the actual barometric pressure. So my question is what does 23.65" for example tell you other than that you are high in elevation.

Has anyone ever seen a barometric pressure of let's say a hurricane at 23.65", of course not.

Why not both, although I agree we should use adjusted barometric pressure. In it's current form it does not provide me any valueable info, but I'm just a technical project manager who loves meterology. :)

Ian
01-01-2007, 03:03 PM
What does baramotric pressure really mean anywhere? I always supposed it was the change that was important. Absolute and Relative would both provide this information, but only the former tells you how long it will take to cook your ramen.

I like the Physio-Relative scale, I mean if your taking shelter in a crevasse with one hundred mph winds over head, your practically pulling a vacuum.

nhwxtracker
01-03-2007, 08:27 AM
One reason why the Observatory does not report standard pressure is that it is not an airport. The main reason other stations report pressure is for landing aircraft, Mount Washington does report its pressure in the synoptic code.

Bill O is correct in stating that pressure at that elevation is not as accurate and will vary greatly especially in high wind events.

Patrad Fischroy
01-03-2007, 02:53 PM
So that landing field on the east side of the observatory doesn't get all that much use? :-)

wareagletsf
01-08-2007, 04:35 PM
Using average sea level pressure of 29.92 inches of mercury as a point for comparison, the highest barometric pressure ever recorded in the USA was 31.85 inches in Northway, Alaska, in January 1989. The lowest barometric pressure ever recorded was associated with the landfall of the Labor Day hurricane in Key West, Florida in 1935, which registered a minimum pressure of 26.35 inches of mercury. Both are also records for North America. From USA TODAY

Bill O
01-08-2007, 04:40 PM
Using average sea level pressure of 29.92 inches of mercury as a point for comparison, the highest barometric pressure ever recorded in the USA was 31.85 inches in Northway, Alaska, in January 1989. The lowest barometric pressure ever recorded was associated with the landfall of the Labor Day hurricane in Key West, Florida in 1935, which registered a minimum pressure of 26.35 inches of mercury. Both are also records for North America. From USA TODAY

Too bad we can't compare those to Mount Washington since they don't adjust to sea level. Last fall an intense coastal low moved just south of my house and the pressure dropped to 28.81".

hanseljas
02-27-2007, 08:33 PM
At my staion we report station pressure mainly for ATC and other reasons that I'm not too sure about and also it makes seeing fronts and other such events easier.

awolff
04-06-2007, 09:47 AM
I am only curious about the weather at the summit, that is where my interest lies

Maybe you're being a little self centered? Barometric pressure is Barometric pressure. If your interest lie in meteorology then you convert it to sea level so you can compare it to hurricanes and what not. The rangers and the instruments just report the data...I am assuming you're a scientist..you interpret it the data however you want..compare it to sea-level or compare it to the moon for all I care.

BTW...Mount Mitchell barometric pressure is not adjusted to sea-level either.

Mt Mitchell Rocks!