Apparently the NAM is correct so far…low pressure is developing off the Washington Coast, pulling back the dreaded south and southwest wind up the Valley and over the Coast Range. The arctic boundary (front) appears to be in a line from around Hoquiam to Chehalis to Mt. Adams west of the Cascades. Areas to the south of that are getting a mild south wind (including metro area), to the north it’s cold and snowy. Until the low pressure passes by late this afternoon, we stay in the “warm” airmass.
All models show the arctic air surging south behind the low this evening, supported by the incredibly cold upper-level trough dropping south. THAT is our last chance for snow…with the arctic front. We’re talking after dark. Now obviously models have trouble with the small-scale details…for example once again there is more precipitation than expected today (just too warm!). So we should get at least a dusting as the precipitation ends, maybe an inch or so if we get REALLY lucky. Unfortunately the UW-WRFGFS decided to fail it’s morning run today (too cold?), but our RPM shows a brief burst of snow right along the arctic boundary; supposedly around 7pm. We’ll see. I will say that is the one feature our model has been very consistent on, regardless of where the low presssure system was expected to be today.
Disappointing for the snow lovers (I mean people that love snow, not lovers hanging out in the snow of course). But it IS weather and half the excitement is the anticipation. Plus, we still have the coldest November airmass in a generation descending on us tonight!
So here’s my latest forecast:
Portland Metro: Rain/snow showers today…streets remain wet until at least sunset. Then a Trace to 1″ of snow sometime after 5pm. Clearing and freezing up by 10pm.
Salem: Mainly rain showers today, then a mix or all snow showers briefly sometime between 7-10pm. Could get a dusting then…freezing up after midnight.