December 08, 2013

Snow and Freezing Rain Tomorrow?

 6:30 AM Update

The coastal radar shows a weak area of snow showers moving over Hoquiam and the SW WA coast and moving inland over SW WA (see echo).  Very light stuff.   NOTHING ELSE OUT THERE. So some light snow showers over SW WA is all that we will see this morning.  Update for the evening commute and overnight at noon.  Could be snow showers this evening.

The forecast for Monday is a very difficult one.  

We will have air that is quite cold enough to support snow tomorrow morning.  A very weak weather disturbance will approach during the mid afternoon and will bring some light precipitation to the area.  As the disturbance moves through temperatures will begin to warm as increased onshore flow occurs.  By Tuesday morning commute time it will probably be warm enough for rain over Seattle, with snow holding a bit longer over NW WA.

So for those of your worried about driving to work tomorrow, the morning commute will be fine.  No problems at all.  Enjoy.

South Seattle should be substantially rain shadowed (or snow shadowed in this case). So if snow falls, it probably will be heavier in the north part of the city--but still not more than an inch.  Could easily be much less.  As the temperatures warm up aloft, we might see a few hours of freezing rain.

To illustrate, here is the 24 hr precipitation and snowfall ending 4 AM on Tuesday AM. The mountains will get snow ...guaranteed and NEEDED.  NW Washington including Everett to Bellingham to the San Juans will get perhaps an inch. Between the rain shadowing in NW flow and warming, Seattle to the Kitsap will not get much...perhaps 1/4-1/2 inch at most.  Or virtually nothing.

 Not a big event...but any snow in our area can cause problems.  And we could get a few hours of freezing rain.  God knows what the TV stations will make of it!   We will have a much better handle on this tomorrow..I will do a NOWCAST around noon. 

Temperatures are already warming quickly aloft.  Take a look at the wind and temperature above Seattle Tacoma Airport. At around 5000 ft (850 hPa on chart)  the temperatures have warmed from -12 to -6C (that is a warming of around 11F). 

Watch the radar will see in real time what is happening.  Precipitation amounts will be everything.  No worries.  If you see it coming in when you need to be driving or might get an early start.  No big blizzard, but roads can get slick with a little snow.  Sea-Tac Airport is 4 F warmer than the same time yesterday--that is true for many local stations.   Changes are beginning....

Finally, for those in my ATMS 101 class taking their final exam tomorrow at 8:30 AM....there are no snow excuses.  Be there!


  1. Cliff, I'm curious as to why Seattle is forecast to warm up enough for rain to occur at 4 am Tuesday morning while the SW Washington Interior is forecast to have snow through 4 pm Tuesday and then another shot at wintry precip Wednesday night? Is it a disagreement between NWS Seattle and NWS Portland? Or are conditions set up for Seattle to just naturally warm up quicker while SW Interior stays entrenched in cold air for a longer period of time?

  2. Here's to hoping the Kitsap prediction holds. My fellow school bus drivers will start the 'snow talk' this morning. I will tell them not to worry and show your app to them.

  3. Certainly a case for poor correlation between eye-ball cloud threat assessment (EBCTA) and radar this morning (monday). Leaden skies, chill, still... can the blizzard be far away?? but the radar says 'nope', and in radar we trust.

    In terms of (false?) human sensory perception of weather forecasting, i always wanted an explanation for the 'smell' of an on-coming snow (?)

  4. If I have a final that finishes at 430p, will I be able to make it home? Could I use the noon NowCast as an excuse?

    Just curious, how often has the Drumheller fountain completely froze over?

  5. Any explanation for the interesting temperatures from the Olympia Airport reporting station? I noticed late Saturday evening that, while all the other stations--including my own--were reporting steadily decreasing temperatures, the airport was reporting above-freezing temperatures. Today, as of a few minutes ago, it was reporting 41 degrees--I wish! It is 27 in my yard, close to the sound, and the other reporting stations report similar temps. Has a bird decided to roost on it??

  6. I keep hoping for some more fun from the skies here in the Mid-Willamette Valley, but it looks like its gonna stay up North!

  7. All in all a boring cold snap! I don't wish misery on people, but it's been closing in on 2 years since the last decent snow...

  8. All in all a BORING cold snap (or cold nap). I don't wish misery on people, but it's been nearly 2 years without a decent snow now...

    So far this fall/winter is on pace to be wimpy, wimpy.


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