Best freezing level for volcano skiin'.

So, let's say there has been a long window of clear weather.<br><br>Then let's assuming you are going to ski a southerly aspect of a Cascade volcano.<br><br>Then, what's the best freezing level for silky corn?<br><br>If it's sunny and the freezing level is 8,000 ft, do you think that's better than sunny and freezing level of 11,000 ft?<br><br>Do you think the snow will be rotten at 8,000 ft if there are a few days of 11,000 ft freezing levels?<br><br>-Matt

If only it were that simple... <br><br>if I were going to ski the south side of a volcano, I'd probably want the freezing level to be no more than 2000ft below my high point, if I wanted corn and not ice.<br><br>Of course, the wind will help determine how much it really softens.<br><br>Need to take nighttime temps into account too.

The night time temps are crucial, as well as the state of the snow pack.<br><br>In mid summer (later than mid June) I wouldn't ski a volcano without freezing levels above the summit, and I wouldn't plan my descent until well into the afternoon.<br><br>In late spring, like say this weekend, with recent snow and no real consolidation, things will get mushy at most elevations if there isn't a hard freeze over night. Even with a hard freeze, if it is unconsolidated below they will still get mushy. I'd imagine you want cooler temps -- with sun, most slopes will soften enough for good skiing (only takes a little).<br><br>This time of year, north/south aspect has little to do with the amount of sun a slope receives because of how high the sun is. The north ridge of Baker for example gets sun all day in June. More relevant is east/west facing. West facing slopes get sun later in the day and will stay harder longer than east slopes. So if you are trying to do a big volcano take that into account -- prime time to ski the Boulder will be earlier in the day than the Coleman, for example.

Nice responses Matt and Phill. I bet Amar has a thoughtful answer to the question too (which may very well be a chapter in his book! ).<br><br>I have a related question:<br>Are the NWS freezing levels that are forecasted for night, the highest the freezing level will be during the night, the lowest or some sort of average?<br><br>For example, in the NWS's No Oregon Cascades Forecast , tonight the freezing level is forecasted at 13000 feet. Does that mean the lowest the freezing level is forecasted to reach is 13000ft, the highest is 13000ft, or that is the average? The same question applies to day time freezing level, though I think they are the highest? <br><br>In the past few days I have tried to answer this question by looking at telemetry and Salem weather sounding data . On Monday night the freezing level was forecast to be 9000ft, however telemetry @ 7000ft reported the temp as 31 at 1am. This concurred with the Salem soundings which were taken at 5am our time (1200Z) recording the freezing level at 7320.35 ft (that's read from the text data )<br><br>Last night (Tuesday night) the freezing level was forecasted to be 12,000ft. At 7000ft the low reached on telemetry was 41 @ 10pm. However the 5am soundings listed the freezing level at 13254.45ft and suggested an inversion. Yikes!

Typically the temps forecasted are the day time highs and the night time lows. I'm not so sure about freezing levels, but it may follow the same convention. I do suspect that the freezing levels they forecast are the "free air" freezing level, ie, the freezing level you would get in a sounding like the Salem sounding. The actual temperature at the ground will be lower than this on a clear night due to radiative cooling, so the freezing level on the ground on the actual volcano will be lower than the forecasted value. If you go up a little bit into the sky, things quickly close in on their free air values (not sure if the telemetry station at Timberline is on a tower; if so this would affect this, as would some wind).

As indicated by all, these things can be complicated.  Last night I skied some north facing mush right at sunset (±4400-5400 feet), and although air temps were well up into the forties, a frozen crust was just beginning to form in some areas.  Surely by morning it was frozen solid, and by noon probably thawed into wondrous corn; that's the effect of radiational cooling when the sky is clear.  In fact, no crust had formed at the highest elevations around the little summit, where a little localized cloud cap had formed due to uplift, preventing radiational heat loss. <br><br>The other factor mentioned above is wind.  On a windy and cold day, aspects and elevations that might otherwise thaw in the sun can remain frozen.  OTOH, warm winds can accelerate softening, and uplift can form a cloud cap which will make your life miserable for a not-insignificant portion of the descent--say, the first few thousand feet--either by preventing any sun-softening at all or by allowing just enough to leave you skiing endless expanses of breakable crust.<br><br>And so on: the permutations are endless (probably a good thing, since what else would spring skiers talk about all week in anticipation of the weekend?).