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Sirhc978 t1_j72705n wrote

WMUR was saying the windchill on Mt. Washington could be -100F and that the troposphere might actually dip below the observatory, putting it briefly in the stratosphere.

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Mapsachusetts t1_j7282dc wrote

Well I wasn’t going to go hiking this weekend but this might be my only chance to visit the stratosphere so now I have to reconsider…

(/s just in case.)

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TheCloudBoy OP t1_j727yup wrote

I suspect that happens! They (WMUR) waited until the NWS highlighted that, even though this scenario was clearly in play to any sensible meteorologist multiple days in advance. This mechanism is called a tropopause fold and part of the reason why the winds are expected to accelerate so much atop Washington (see the Bernoulli Principle).

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WhoWhatWhereWhenHowY t1_j72gmqw wrote

This is really interesting. I had never heard of a tropopause fold before. I tried a brief search to figure out the mechanisms that cause it but is it just a strong high pressure system?

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TheCloudBoy OP t1_j72ism2 wrote

Hey I'm glad meteorologists can teach people new things! So not quite, a tropopause fold/depression occurs just behind a upper-level jet stream associated with a strong cyclone, in this case a piece of the tropospheric Polar Vortex that's been pinched off.

The reason why Bernoulli acceleration occurs at the fold is a difference in density: the bottom of the stratosphere directly above the tropopause gets increasingly warmer, drier, and therefore more stable than the airmass below it. So, that rapidly increasing stability creates the "flow squeeze" effect between the fold and the White Mountains, thus accelerating the winds.

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WhoWhatWhereWhenHowY t1_j72l009 wrote

That is very interesting. I have to say one thing that has always blown my mind with meteorology is how much air doesn't like to mix and can have huge velocity gradients that I wouldn't expect from fluids. How a tornado holds itself together is just magic to me.

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Belowmylevel t1_j75kfox wrote

Do you have a visual aid that helps explain this by chance?

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