Northwest Daily Snow
By Larry Schick, Forecaster Posted 7 years ago January 17, 2017
The Mix: snow, freezing rain, and Rain
Summary
Expect an increasing wintery mess today and into Wednesday. A real mixed bag of snow, then freezing rain, then just rain as the snow level rises. Not ideal ski conditions for the next two days. We have cold air in place and a weak weather system is moving in early today with a combination of some snow and possible freezing rain – eventually ending with rain as the snow levels rise to 5000-7000ft, late in the day. A 1000 ft lower SL at Whistler, higher by a 1000 in Oregon – but everyone vulnerable to the mixed precipitation type - especially in the passes.
Short Term Forecast
A second, stronger wave comes in later today into Wednesday and that really scours out the cold air – then it’s all rain, with the SL 5000-6500ft and 3-6” of rainfall into Wednesday…ahhh! Some of the highest ski slope elevations could survive with snow only – especially Whistler. But it might be wet snow. Later Wednesday the snow level will drop a bit by 1000 ft, with a more significant drop, late Wednesday and Thursday.
Below is the 24hr rainfall ending Wednesday afternoon (black is 2-5", mainly rainfall)
infall)
Extended Forecast
The good news is the nasty weather only lasts 36-48 hrs. By Thursday expect cooler weather with a snow level of 2500-3000ft through the weekend, with snow showers at times, coating the rain soaked snowpack with new snow ( 3-6”).
Below is previous the 24 hr snowfall ending Thursday afternoon - favoring Whistler/North Cascades.
Rain on Snow: Busting the Myth - prove it to yourself
Rain falling on snow does not significantly melt the snowpack. This is an overblown myth, which refuses to die. Studies indicate 0 to 23%, of stream runoff, in a rain on snow event like tonight, is from snow melt. So yes, there is some melt, but it’s relatively insignificant and sometimes near zero, as a deep snowpack can absorb rainfall, with no runoff. Strong winds can increase the rate. Heavy rain always drives the flood in the winter for the Western US. You can see what happens in this storm by checking out NRCS SNOTEL sites and watch the heavy rain and minor melt. Watch for changes in SWE loss. Compare the rainfall to SWE (snow water equivalent) loss. NRCS SNOTEL in Washington: https://www.nrcs.usda.gov/wps/portal/nrcs/detail/or/snow/?cid=nrcs142p2_046350
Larry Schick--Open Snow NW