Friday, February 8, 2019

A Snow Event in Two Acts

Today's snow event will be in two acts, with the first one already begun.  Very light snow is now falling over Northwest Washington (locations such as Bellingham and Orcas Island)--something that is confirmed by the 8:30 AM weather radar (see below)


These snow showers are associated with an approaching upper level trough of lower pressure that is providing upward motion that is leading to a band of clouds and weak snow showers (the satellite picture at the same time is shown below).


But this is not the main act.  That will occur as the upper trough spawns a tight low pressure center in the lower atmosphere, as illustrated in the surface pressure forecast for 7 PM tonight.  An absolutely classical pressure pattern for a snow event over Puget Sound.   The low pressure draws in cold air form the north (note the large north-south pressure change) over Puget Sound and pushes moist air from off the Pacific above the low-level cool flow.


Close in to a major weather event, I like to look at the NOAA/NWS High Resolution Rapid Refresh Model--in which a new high resolution forecast is made each hour.  Below shows the accumulating snow in time.

There is  some light snow reaching Seattle around 11 AM....but this is stage 1 stuff.


The snow extends south by 4 PM at which time the amounts are just starting to increase.  Stage 2 is beginning as the low center develops along our coast.


By 10 PM tonight, there is a lot of snow as stage 2 revs up ...4-6 inches around Seattle and more to the east. There is going to be a region of heaviest snow where the moist flow off the Pacific converges with the cold flow coming out of the north.


And by 1 AM, there is a bit more around Puget Sound, but much more over northwest Oregon.


The essential point in all this, is that things should not be too bad before roughly 2-3 PM, but by rush hour, the situation should be declining rapidly.  The UW is closing around 12:30 PM, which is wise, since it allows folks to be home by mid-afternoon. 

Later today I will talk about the next big snow threats... late Sunday/Monday for SW Washington and Oregon and Tuesday for Washington.  Today is just a "warm up" as cold air remains in place for most of the week.   And no, I won't give a name to the upcoming snow events (but the picture below is a hint)




217 comments:

  1. Where are you at in Gig Harbor. We just measured 11” here at our house on 70th ave NW & 45th.

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  2. 8 inches in Bonney lake, thanks cliff you were spot on for us!

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  3. I certainly respect everyone who did get a good dumping. I'm the guy in Monroe/Woods Creek, and the storm seems to have mostly avoided us. We got the bulk of our snow before 3pm, and then the wind blew it all over the place, so we have areas on our farm with 6 or more inches built up and others that have been blown down to 1-2. No appreciable snowfall overnight.

    Guess we got unlucky this time around. (Or lucky, depending on your point of view.)

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  4. Meanwhile back at the ranch in Bellingham (crickets).

    It’s been snowing offshore all night. Gosh it’s hard to bulls eye this stuff.
    Cliff’s reject fail students go the dakota’s where it’s flat as a predictable pancake. “we have rain moving in from Wyoming”.
    “You don’t say”.

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  5. Any news for the rest of the weekend?

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  6. 6-12 inches depending on location in maple valley/covington

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  7. 22" on Bell Hill near Sequim and still snowing. That's fresh snow. We still had 6" of compacted snow left from the 8" Sunday storm. So say 30" of snow fall for the week so far.

    If the predictions for today and Sunday through Wed hold, then we're probably talking 40+" in ten days.

    Even the 9-11 Paramedics in Sequim reported being snowed in. Everyone's on their own until the plows catch up, and that'll be the main streets. Residential streets and hills are "self rescue" locations now, just as they will be after a big earthquake.

    Didn't expect that from this storm.

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  8. 1 inch in snohomish yet 6 inches in Clearview a mile away. So localized...

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  9. Sat 9:00 Am here in Bow, Wa. We did not get a lot of snow - it stopped in Friday afternoon - but enough to keep it wintery and the reporting rock covered in white!

    I suppose weather forecasts now a days are sort of like beer. All good, some just better than others.

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  10. Under two inches on the North end of Camano Island

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  11. I'm Unknown from 8:14p yesterday, NE of Woodinville. We did ultimately get about 4" (hard to tell--we still have lots of snow from the last one), but more than half of that was from the afternoon, and it's far less than what we got last weekend (8-9"). So snow happened, but not quite the pattern that was advertised here at Lost Lake.

    Kind of wondering when the roads will be safe for my small car again...

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  12. 10 inches just before 11 am in Port Ludlow up on the hill.

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  13. Thank you Cliff Mass. And shame on all you ditherheads who ignored the entire “second wave” prediction and jumped on the blame wagon. You would think y’all paid for all the information, education, and experience which went into his PREDICTION that he graciously shared.

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  14. Wondering what the colored numbers indicate on the map above showing northern Washington and southern British Columbia. Could someone tell me? Thanks.

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  15. No reason for smug comments here, either from naysayers or the believers. Weather forecasting isn't about being completely right or totally wrong. Weather services provide probabilities and estimates. Science is predictive, not 100% certain. Many Washingtonians have problems with uncertainty - even some of the TV anchors who pronounced at 7 pm that the storm had peaked.

    Now please get your kids vaccinated for measles! It is much, much more likely they will be harmed by measles (and harm others) than be harmed by the vaccine.

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  16. So many trolls , so little time.....

    Because you’re too busy shoveling

    Bahahahahhahaah

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