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Brad
03-04-2008, 05:38 AM
It looks like the summit temp got up to 35 degrees earlier this morning and is back down to 31 now. Here is the ARVTP which has some interesting variations.

http://images31.fotki.com/v1085/photos/1/1002902/4071997/ARVTP20080304-vi.jpg

Mike D
03-04-2008, 10:15 PM
I saw on Sunday on the Current Conditions page (http://www.mountwashington.org/weather/conditions.php) that the summit and both the 5300' and 4300' sites were at 9 degrees F. Could that be right? and sure enough, they were all between 8.5 and 9.4. Very unusual coincidence.

MikeValletta
03-05-2008, 03:44 PM
I'm not quite sure, but how is it possible for days to be warmer on the summit, being 6,000 feet up comared to being cooler on the base, about 2,000-3,000 feet up? Todays reading for 35 on the summit, and 28 on the base of the auto road did indeed confuse me.....

Mike D
03-06-2008, 10:59 AM
That is an inversion. I am not a meteorologist (enter Bill, eg.) but I understand that to mean that the air is unstable. Anecdotally, I used to live in the crux between two hills; our house always had more dew than our uphill neighbor because cooler air would settle into the U and condense more readily. That's a very small example of why cooler air might end up below warmer air.


I'm not quite sure, but how is it possible for days to be warmer on the summit, being 6,000 feet up comared to being cooler on the base, about 2,000-3,000 feet up? Todays reading for 35 on the summit, and 28 on the base of the auto road did indeed confuse me.....

Bill O
03-06-2008, 11:13 AM
I'm not quite sure, but how is it possible for days to be warmer on the summit, being 6,000 feet up comared to being cooler on the base, about 2,000-3,000 feet up? Todays reading for 35 on the summit, and 28 on the base of the auto road did indeed confuse me.....

This is very common in the winter, and 35 to 28 isn't a very extreme inversion. Its not uncommon to see sub zero temps in Berlin and near freezing temps on the summit.

Clear, calm nights produce the most inversions, but they can also occur when warm air over runs cold air in the valleys. Since the cold air is dense it will not rise into the warmer air above.

You can even go to your local park or golf course on a clear, calm morning and experience how the cold air has pooled in the low spots.

Places like Salt Lake City often get trapped in winter-time inversions for weeks at a time. The low lying valley will have freezing fog, cold temps and increasing air pollution while the nearby ski areas are clear with temps in the 50's. This is common in the winter because the weak sun cannot warm the valley enough to mix the stagnant air.