Sunday, March 15, 2009
Snow piling up at Silverdale this morning (thanks to Dale Ireland cam)
Huge flakes are falling around the area right now. In the central Sound it is really not accumulating at the surface because the temps are too warm...but cams in the south sound show perhaps a 1/2 inch. It is much worst on the Kitsap and near Hood Canal...take a look at Dale Ireland's cam in Silverdale(attached). This is what the models were indicating last night. The precipitation is front a a warm frontal band associated with the incoming system and temperatures are just cold enough for very wet snow (see radar).The snow is full of large aggregates (many crystals stuck together)...that is why they are so large (the surfaces of the snowflakes are melitng and wet...and this acts as a sort of glue to allow them to stick to each other). This happens in marginal temp situations, like we have now.
The Seattle profiler temp soundings show how temps are just at freezing above us (subtract 1C from the values shown--this is actually something called virtual temp which includes moisture effects). Evaporation and melting of snow from aloft helped to push us over. Anyway, enjoy it...it won't last. The warm front will move warmer temperatures into us in a few hours and end the snow for everywhere except near the Olympics...and even there during the afternoon.Want to see where the warm front is at the surface..check out the surface obs and look towards the Astoria area....southerly flow in the upper forties on the N. Oregon Coast and easterly flow in the 30s along the central WA coast. The warm southerlies will move northward this morning.And later it will get breezy later today...although the latest model runs indicate the low will be crossing Vancouver island sufficiently north that Puget Sound will be spared the strong stuff.
9:30 Am..the air is warming rapidly aloft and it is raining...
PS: I am heading to Bainbridge today (Eagle Harbor Books) at 3 PM today to talk weather..and Olympia tomorrow (see info to the right). Will have to shovel my driveway first!
Posted by Cliff Mass at 8:23 AM