Is it going to snow Friday? Briefly, for some

December 17, 2013

If you’re looking for a snowstorm, this isn’t the setup for the Portland Metro area, but a lot of us may see snowflakes at least in the air on Friday morning.  Here’s what’s going on this time around:

A cold front drops through our area tomorrow afternoon, with a nice line of showers, dumping snow down to about 1,500′ just before and around sunset.  Then we dry out and turn chilly as a Canadian air mass descends over the Pacific Northwest for tomorrow night and Thursday.

A strong warm front surges right on in over the leftover cold air late Thursday night and early Friday morning.   This sets us up for a (very) brief period of snow at the lowest elevations from the Portland Metro area north into Western Washington.

The change is going to be most dramatic in the mountains.  Government Camp goes from 52 today, to about 35 tomorrow, 28 Thursday, then back up to 40+ Friday and into the weekend.

Timing will be everything with the possible action on Friday morning.  If the precip arrives late, a mixing south wind may start to develop, if the precip arrives early (before 7am), we could all see a dusting briefly.  Luckily we have 2 more days to figure things out.

I do notice on the evening models (especially the WRF-GFS and our RPM), there is little to no mixing until closer to 10am.  They also both show heavier precip to the north of the metro area.  That’s why I mentioned Clark county in these graphics:

MarkSnow_PortlandOutlookPercentages

MarkSnow_PortlandOutlookPercentages2

Whatever happens, by midday the snow level will be jumping to around 8,000′ and it’ll be raining even at the ski resorts!

My gut feeling is that it’s not going to affect anyone’s life much at all from the Columbia River south…we’ll see.

 

By the way here is the snow forecast from our RPM:

RPM_SNOWACCUM

and the 00z WRF-GFS:

wrf_snow
Chief Meteorologist Mark Nelsen