Friday, December 23, 2016

Minor snow today

It is the old story, the temperatures are marginal for snow near sea level around western Washington.

 At 10 AM, some locations around Puget Sound were reporting mixed rain and snow, and some higher elevations (like Paine Field in Everett) were all snow.    However, the temperatures aloft are relatively warm and the road surfaces have warmed after our relatively balmy weather.   So not much is sticking.  But you can see flakes on some web cams (see one near Paine Field below), with some whitening on grass.


 The issue:  warm temperatures above.   A plot of temperature with height at 9:30 AM shows a freezing level of 1750 ft, which implies a snow level of 750 ft.   Yes....the higher hills could get some accumulation, but not much near sea level.

A plot of temperatures aloft (over Seattle) in time, shows -2C air at 850 hPa (around 5000 ft).  That is extremely marginal for snow, particularly when one does not have cold air in place at low levels.

The forecast pressure pattern is also not favorable, with a low center right over us and no feed of cold air from the Fraser River Valley (see forecasts of pressure and temperatures for 10 AM below).

The latest National Weather Service HRRR forecast (made every hour for 18 h) suggests some very light snow north of Seattle...and remember that is NOT snow on the ground, but what falls out of the sky. (see example of snowfall ending 11 AM)
Bottom line:  if you are near sea level, you will not see much and there is very little risk of significant snow.  If you are above 500 ft, you will see some very light accumulations. More over Whatcom county.

Sorry for folks wanted a white Christmas at sea level.   But there is plenty of snow in the mountains.

12 comments:

Cameron Chapman said...

Light snow turned to mixed flurries for an hour, then rain/snow mix.

10:43 AM 12/23/16 Bothell, WA 103rd PL NE

Cameron Chapman said...

Light snow turned to mixed flurries for an hour, then rain/snow mix.

10:43 AM 12/23/16 Bothell, WA 103rd PL NE

Darin Berdinka said...

I don't know. It's been dumping in Bellingham all morning. 2 inches so far and doesn't look like it's going to stop.

Space Monkey said...

Totally different story up here in Whatcom county - it has been snowing heavily and steadily since around 7 am with no letup. 2-3" accumulation through most of Bellingham and likely higher amounts away from the water. This is more snow in a single event than we received during last week's storms.

As recently as last night the prediction was for potentially a little snow, late in the day, and only at elevation - given how far that was off the mark, not sure what to expect in terms of further accumulation or how long it will last.

TheBugBlog said...

I'm in North Whidbey at 250 ft above sea level and have just under an inch of really wet snow.

Unknown said...

In Arlington Heights at 200 ft elevation, about 4 miles east of Arlington, WA, it has been snowing solidly for about 2 hours now - close to 1 in. so far.

Sita said...

I'm in the Eastgate/Factoria area and it's been snowing steadily since about 11:45. It's not sticking yet but I live in hope (with expectations of it not sticking).

Sita said...

It hasn't been sticking yet (i live in hope) but it's been steadily snowing here in the Eastgate/Factoria area since 11:30 am and is still coming down.

Unknown said...

In Woodinville at 400 ft its been snowing since around noon. The soft surfaces are covered with about 1 inch and it is just starting to stock to the roads and driveways.

Colleen said...

In Whatcom County it snowed much of the day, contrary to forecasts. Treacherous conditions in the morning led to a host of accidents. Flights out of Bellingham have been delayed at best & in a few cases, cancelled altogether. Not minor for a number of drivers, or for those of us who have air travel plans this weekend.

Jay_North said...

We Bellinghamsters are all excited. With 2-3 inches on the ground and the light rain ending we have a good shot at a White Christmas - not like the ones I used to know (upstate NY), but good enough for around here!

Bryan Black said...

16 day GFS is showing a very ominous trend after Jan 1. Modified arctic air meeting up with some moisture. Will be interesting to watch.