January 10, 2012

Increasing Threat of Snow

The new forecast models are increasingly threatening for colder temperatures and lowland snow from Sunday through Wednesday of next week, although none of the forecast are ideal for a truly major event.  THUS THIS EVENT SHOULD NOT BE OVERHYPED!  At this point we are talking about good snowfalls in the mountains and snow showers over the lowlands.

But you might consider getting prepared:  make sure you have chains and windshield decider for your car, be ready to protect sensitive plants-- you know what I mean.  The TV stations should get all their colorful parkas cleaned and ready (no KING-5 Jim Forman jokes...yet!).  And local DOT folk should stock and make sure their staff are well rested.

  On the left is the average of the ECMWF (European Center for Medium Range Forecasting) ensemble forecasts for upper levels (500hPa).   The average or mean of an ensemble or collection of forecasts tends to be more accurate than individual forecast model runs.  ECMWF has the world's best global ensemble. The right is their single "deterministic" forecast.   Both show an upper trough offshore--a pattern very close to the typical western Washington snow configuration.   The U.S. model, which initially was much less threatening, has now come much closer to the ECMWF solution.  Snow forecasts are always uncertain because it is difficult to be cold and wet west of the Cascades at low levels.  The move to colder temperatures is MUCH more certain.

  Our high-resolution regional models, forced by the NWS GFS model, indicates some snow (light) on Sunday, and a more serious threat Tuesday, but there is lots of uncertainty, of course, at this range. Below is the 24-h snow prediction ending Monday at 4 PM.  Lowland snow in the forecast, especially over southwest Washington.   There is a significant possibility of a convergence zone snow even (Seattle to Everett) late on Sunday into Monday.  Will watch out for this!

The mountains are going to get it..no doubt about that...which is very good news for skiers.  Wax your skis!

KBTC-TV aired a nice segment on the new coastal radar, click here or below the picture to view it.


  1. Woo hoo! Would love to see this forecast come true.

  2. hope this pans out!

    I'm curious how you are getting 24h snowfall graphics for 144h out? I always navigate the models via here: http://www.atmos.washington.edu/mm5rt/rt/otherdates.html

    and the last hour is 84h out?

  3. Do you think with this first trough, with a NW trajectory, the air will be cold enough for snow in downtown Seattle? Jim might be well advise to set up camp at the top of Queen Anne or near the PSCZ.

  4. Hmmmmmmm.....Everyone's talking about this....all the models "seem" to be in agreement, except for "small" differences...Even Cliff is talking about it! I told myself last fall, when they were hyping this La Nina winter again, that I was not going to get sucked into their hype about possible lowland snow until it actually happened. But when Cliff starts talking about it that makes it hard not to get hopeful. BUT....it is still 4-5 days out.....I think I'll give it another 2 or 3 days of consistant model runs before I get too excited, and before I get my kids excited! Keep us posted Cliff!

  5. I just wish it would come in time for the weekend. Skiing is not so great right now until the new snow comes. Wish I could play hookey next week.

  6. I'll get excited when we're a little closer AND I don't see the color white for snow totals over the Seattle area. That means little to snow in my book. Any hype for that = BUST. ;)

    The middle of next week might as well be next year for the reliability of the models. Still, we haven't even had much potential for snow this year.

  7. Great video on the Langley Hill radar. Congratulations all around.

  8. *quietly* Forman, Forman, Forman!

  9. Well, the 6-10 Day Outlook from today appears to look pretty good for snow in the Pacific NW:


    And forecast confidence is above average.

  10. I know the NAM has a cold bias but the 00Z shows the -10 line to the Wa. coast by 4 pm Saturday afternoon :)

    We'll see

  11. This is a joke right? A snowfall map 144hrs away, lol. You know what a pitaful winter it has been you're clinging to maps like that.

  12. Dr. Mass, I would really be interested in reading a column from you about the Euro model vs the GFS, and why is the US GFS model so inferior? I know they upgraded it (supposedly) last year. Is it performing any better then the old one?

    I also know they are going to upgrade the ensembles with a higher resolution. Hopefully that can help. Are the ensembles and the ensemble mean the best tool for the mid range?

    Anyway, seeing how the GFS has been so inconsistent the last few days, where the Euro and even the GEM have been consistent, it makes the GFS in this situation almost useless.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

Winter-Like System in May

Tomorrow will not feel like late May, with a winter-like Pacific weather system making landfall, bringing lots of rain, wind, and cool tempe...