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View Full Version : what will wind chill be next couple nights??



rockin rex
03-05-2007, 03:02 PM
Looks like temp will be -30 or lower along with high winds next couple of nights. Any guess on what the wind chill low will be. I figure -30 with 40 mile an hour winds is around -100. This is rough estimate. It is going to be cold!!!!!!!! Time to check what that expedition gear can really do.

Bill O
03-05-2007, 03:34 PM
There's no reason to guess. I'd start playing around here. (http://www.weather.gov/os/windchill/index.shtml)

-30F with 100mph wind gives a wind chill of -84F.

Arthur Dent
03-05-2007, 03:59 PM
Wind chill as shown on the NWS site is not a linear function but is an asymptotic function so that higher wind speeds affect the wind chill less and less until it has no added evaporative cooling effect. The new wind chill formula the NWS started using in 2001 is closer to reality as far as the cooling effect of the wind on exposed skin but if your skin is properly protected wind chill has no effect.

I do know what -34°F on the summit feels like and I remember that when it get close to that temp the summit building makes some very pretty strange (and loud) cracking noises as the cement and encased rebar contract at different rates.

Bill O
03-05-2007, 04:17 PM
I do know what -34°F on the summit feels like and I remember that when it get close to that temp the summit building makes some very pretty strange (and loud) cracking noises as the cement and encased rebar contract at different rates.

Yes, that's fun. You'll start getting those popping noises in the negative teens. Coldest it has been when I was up there was -27F or so. The popping noises really get your heart rate going. Somewhere between a gunshot, furniture falling over, and a door slamming.

I live in a 100 year old factory converted into condos. Mostly brick with some large supporting timbers. When it gets below 15F we get the exact same popping noises. Just like living on Mount Washington.

Steve M
03-05-2007, 05:47 PM
Expansion and contraction of a concrete wall of those extremes doesn't sound like it can be too good for the building. I wonder how long it can stay structurally strong before needing to be fixed or even replaced? I'm sure they inspect the building at least once a year.

rockin rex
03-06-2007, 05:29 AM
-31 temp and -84 windchill. Not a day I would want to be climbing. I bet the summit building is popping tonight. I think this might be close to the lowest temp of the year.

rockin rex
03-06-2007, 09:20 AM
Wow now at -34. This is extreme now, so wonder if someone will try to climb in these conditions. They better have the correct gear if they do try. Not a day for the novice. With these conditions one thing goes wrong and trouble moves in quickly.

Bill O
03-06-2007, 09:34 AM
Coldest windchill I saw was just above -90F. No room for mistakes in that type of weather.

Bill O
03-06-2007, 11:13 AM
Taking some liberties we might be able to infer a windchill of -93F.

Assuming that at the moment it was -36F there were 100mph gusts.

I think all this windchill talk is a bit over the top though. The big story is the temperature, those are the meteorological records that scientists care about. Save windchill for Accuweather and the local tv weather guy (notice I didn't say meteorologist).

rockin rex
03-08-2007, 01:53 PM
Looks like another cold night on the rock pile. Will be interesting to see how low it drops tonight.