At what temp. point does corn not re-freeze with clear night skies and low humidity?

[powski3]

Looking to get out to Hood this weekend but mid to high 90s predicted for the valleys. Stuff freezes up well above freezing at night as long as the skies are clear, but from your experience, what point is too warm even with said nightime conditions?

Sorry if this question is dumb, just trying to get an idea so I don't wake up early and drive up to find crap. Any general consensus on this?

[neck beard]

I am not an expert.

How deep do you want the freeze to be?

I've seen the top few inches re-freeze on above freezing nights due to the snow radiating its absorbed sun energy back into the clear night sky. The stuff will un-freeze very quickly after the crack of dawn.

I don't know what temperature threshold stops that from happening, but it has to be a clear night. I've seen it happen with head high air temps of +5C. Sounds like you will have it much warmer than that.

[pointedem]

No idea about #', but he^ said it. Raidiational cooling can give you a soft freeze with temps 40-ish, tops. Thats with a clear sky and a slight breeze. Ideally, be on the snow no later then 2h post sunrise, and you might still get supportable corn. Maybe.

Good luck. ( I've never skied in the PNW, btw)

[klar]

afaik there are some empirical formulae for night time radiative cooling based on sun down temp, cloudcover, humidity etc but they are not universally applicable, as it is dependent on topography and a bunch of atmospheric parameters. the typical nightly freezing level in summer in the alps is something like 2900-3000m, i think. with a DALR of 10°C/km you'd have to gain about 3000m vertical from the valley at 30°C (90ish°F) to reach freezing, take away say 1000m or 10-15°C for radiative cooling and add some again for a deep enough freeze and my guesstimate leaves you at the conclusion that around 2000-2500m above of where you are now will have wonderful corn in the morning.

[powski3]

Whoa Metric System! As the PNW is in America, that's hard to get my head around. I only understand the random old imperial system, not the rational one based on science.

[snowful]

Top of the Magic Mile was 56F at 0400 hrs this morning.

[PNWbrit]

Looking to get out to Hood this weekend but mid to high 90s predicted for the valleys. Stuff freezes up well above freezing at night as long as the skies are clear, but from your experience, what point is too warm even with said nightime conditions?

Sorry if this question is dumb, just trying to get an idea so I don't wake up early and drive up to find crap. Any general consensus on this?

It's not going to re-freeze this weekend.

[hutash]

0 degrees C, or 32 degrees F. Was this a trick question?

[ZGnzo]

maybe you should just move back to where things refreeze at night, then you wouldn't have all these issues.

http://www.tetongravity.com/forums/s...ad.php?t=85198

[Tri-Ungulate]

afaik there are some empirical formulae for night time radiative cooling based on sun down temp, cloudcover, humidity etc but they are not universally applicable, as it is dependent on topography and a bunch of atmospheric parameters. the typical nightly freezing level in summer in the alps is something like 2900-3000m, i think. with a DALR of 10°C/km you'd have to gain about 3000m vertical from the valley at 30°C (90ish°F) to reach freezing, take away say 1000m or 10-15°C for radiative cooling and add some again for a deep enough freeze and my guesstimate leaves you at the conclusion that around 2000-2500m above of where you are now will have wonderful corn in the morning.

I love it when you get all microclimatological. I get all hot when you say albedo...

Your favourite internetz stalker -

[j/k]

[grrrr]

This morning was absolutely perfect at Table from 0700 to 1000. 44 when I got there, 56 when I left, but the next few days are warming. Sounds like Hood will be mucho warmero.

[enlosandes]

Then there is summer consolidation that occurs and night time temps don't really matter any more.