Climate Prediction (March April May)

Just was looking at the NWS climate prediction center's March-May forecast. Here is my summary: Looks like cooler than usual for the period, but average precipitation. This could be good for climbing and skiing on Mt. Rainier this spring!

Moderate la nina conditions continue in the tropical pacific ocean. Sea surface temperatures (ssts) in the equatorial pacific ocean are below average from around 160e to the south american coast, with ssts between 1 and 2 degrees c below normal in some areas. This very large area of anomalously cool ssts has significant impact on the large scale atmospheric circulation throughout the tropical pacific region, which, in turn, is expected to considerably influence the mean atmospheric circulation patterns over north america.

The temperature outlook for march, april, and may 2011 reflects typical spring la nina condition and favors below average temperatures from washington and oregon eastward across the northern rockies to the western great lakes region. The chances for above average mean temperatures are enhanced from the interior southwest and southern rockies to the central gulf coast states.

Here's the page in full:

http://www.cpc.ncep.noaa.gov/products/predictions/90day/fxus05.html

Snow!

Howdy Everybody! The road crew, after a huge three day effort, plowed their way up to Paradise today! We were able to get the weather and record that 41" of new snow has fallen in the past three days, with a snow water equivalent of 2.82"...so it's drier than normal. Snow stability assessments made early this week observed a 3 to 4 foot crown fracture on southern aspects just below the Barn Flats area. Stability tests near the Canyon Rim lookout on wind ward slopes produced moderate failures about 30 to 45 cm below the surface with Q2 shears. However, these observations were made early in the week before temperatures rose considerably. While the new snow is settling, continued strong westerly winds and additional new snow are keeping the instability high. Hopefully, the road to Paradise will soon be open to the public, and for all those chomping at the bit, cautious backcountry travel is highly advised!

The Castle Snow Pit and a big temperature gradient!

Howdy Everyone!

This week's snow pit was dug in the Tatoosh Range on the east side of The Castle. General observations: 10 cm of great powder on top of a hard, multi-layered, 10 cm crust. As you can see from the graph there are two thin ice layers with softer snow beneath both. The layer of most concern is between 17 and 20 cm deep. Small faceted crystals (i.e., angular crystals) were observed in this layer, which can be expected due to the large temperature gradient in the top part of the snow pack. (Any time the temperature gradient exceeds 1oC over 10cm, the potential exists for faceting.)

Stability tests did not show any propagation, but failures were consistent at 18 cm. The Rutschblock Test showed a failure at 10 cm (the interface between the powder and the icy crust). But I have to admit, the crust was so icy that I slipped before I could get in a good jump on the block.

In summary, the strong temperature gradient and faceted crystals are signs of instability in the snow pack. However, the near- surface crusts are very strong, and seem to be adequately supporting sun-seeking recreationists. Great skiing conditions can be found where the wind hasn't scoured off the powder. Terrain and conditions will vary, so stay alert out there! More precip is headed our way for the weekend. Get out while you can.