Weather speculation: the picture gets … clearer?

We’re going to have a ski race on Saturday.

The weather is going to be … interesting.

The Birkie hasn’t flirted the freezing mark at the start, except for the 2007 debacle, in nearly a decade and a half. The last few years have been cold. And this year? It is not going to be cold. It is going to rain. It’s not going to be warm enough and rain enough that the course will melt off and disappear, but it’s not the usual ski forecast of “soft ski, fine grind, hard wax” for glide and “something in the neighborhood of blue” for kick.

So let’s get to weather. It’s been cold in Birkieland for the last few days. Like -20 overnight cold. So the base—a foot-plus in the woods packed on the trails—is cold, and the ground below it cold. That’s good. It’s going to get warm. Not hot, but certainly warm. On Thursday, after a chilly start, temperatures will rise in to the mid-30s in the afternoon, and won’t go down overnight, making a run towards 40˚ in the overnight hours. On Friday morning temperatures will be in the high 30s with a burst of precipitation, about a third of an inch of rain, falling (maybe less, maybe as much as half an inch; the models aren’t particularly congealed yet). This will be with a passing cold front but that will usher a drier but still Pacific-origin air mass, so it won’t get much colder.

Friday will stay in the 30s or maybe low 40s during the day, which may vary across the trail. What this does to the snow will be interesting. The rain will fall and percolate down through the pack, but may freeze in to the snowpack more than anything since it will retain a lot of cold. There should be enough time for it to freeze in and drain away before the race on Saturday, but it will be interesting. Friday night will be very interesting: temperatures in the 34˚ range will make for a much different race than temperatures in the 29˚ range. Although if the trail is packed, it might freeze up well enough, at least for earlier racers. Right now, it looks like it will drop to right around freezing, maybe a little above, but different parts of the trail may behave differently. So, really, all bets are off in regards to trail conditions.

Saturday appears to be in the mid-30s, breezy, mostly cloudy with a west-northwest crosswind. It will be like 2007, actually, except without a) a shortened race and b) a snowstorm in the evening.

As for the base, it should be fine. In 2000, a fifteen inch base was vaporized over the course of a week before the race (see the chart below). This year, luckily, the meltdown will be much more muted, we won’t have three days with temperatures staying above 40 overnight, and won’t have highs at or near 50 for most of the week before the race. About the same amount of rain, but 15˚ colder and falling on to snow that hasn’t been pre-warmed by a week of warm weather. In other words, it’s not perfect Birkie conditions, but we should be fine.

2000: not a happy time for the Birkie (data from Spooner via NWS):

2000-02-20 38 5 21.5 3.2 43 0 0.00 0.0 14
2000-02-21 43 17 30.0 11.3 35 0 0.00 0.0 11
2000-02-22 52 28 40.0 20.8 25 0 0.00 0.0 10
2000-02-23 48 24 36.0 16.4 29 0 0.19 0.0 8
2000-02-24 56 40 48.0 28.0 17 0 0.00 0.0 5
2000-02-25 51 41 46.0 25.5 19 0 0.33 0.0 1
= No Race 52 40 46.0 25.1 19 0 T 0.0 T

Paul Huttner is calling this a mega-thaw. Well, that was a giga-thaw.

So freak out about wax, and how your body will do in these balmy conditions. But don’t sweat (ha!) the course, we’ll have snow from Cable to Hayward. It just won’t be soft and powdery. But we’ve had eight Birkies in a row with good snow and Main Street finishes, and this should, barring a major downturn, be a ninth.

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