November 30, 2019

Sunday Snow Update

Something called precipitation is approaching Washington State right now--- a quantity relatively unfamiliar this month in our region (see radar at 9 PM Saturday).  Not particularly impressive amounts.  Eugene, Oregon started as a snow/rain mixture and turned rapidly to rain.


This band will move northward during the next 12-18 hrs, bringing precipitation to our region.

The "problem" for snow lovers is that the air above us has warmed considerably today, with a freezing level above Sea-Tac of 2636 ft.  Since it takes about 1000 ft of above-freezing air to melt snow, you can appreciate the issue.  And the air above us will warm as the precipitation, associated with  a warm front, approaches.

Plot from Seattle SnowWatch

The latest UW WRF run, straight off the computer, is shown below.  The plot provides the 24-h snowfall ending 4 PM Sunday.  Not very encouraging for those looking to create a snowman in Puget Sound country.   Seattle's Mayor Durkan can sleep well tonight.

The mountains will get some light snow, as will the eastern slopes of the Cascades.  The hills of SW WA might get whitened, and Portland, cooled by outflow from the Columbia Gorge, could see snow or freezing rain.  Other modeling systems, like the NOAA/NWS HRRR model has a similar solution (see below).

My apologies to snow lovers of the area and to snowplow drivers looking for some overtime pay. 

20 comments:

  1. Cliff, I hope readers aren't too disappointed. Fortunately, there will likely be more opportunities for snow this season!

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  2. Cliff
    We got less than an inch of snow at 250'MSL up the Lewis R. valley out of Woodland, WA. It is melting now. Your forcaste was right on. Thanks for all your efforts for us weather geeks.

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  3. The ground is white here in Richland, Washington this morning.

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  4. Some folks keep posting random comments about today's temperature in Bellingham and elsewhere. Not sure what it is supposed to mean, but the data show that for SeaTac and Bellingham for the month of November that both the average low and average high for the month were a bit above normal and rain was way below normal. The bottom line was November was warmer and drier. This followed an October that was a bit warmer than normal and slightly wetter than normal. The area is quite a bit drier than normal for the calendar year and water year beginning October 1.

    https://www.wrh.noaa.gov/climate/temp_graphs.php?stn=KSEA&p=temperature&mon=9&wfo=sew&year=2019

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  5. The Kitsap Alps picked up about an inch or so. Enough to create winter driving conditions and at least one accident. Its all melting away now.

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  6. Small flakes fell for maybe an hour here in Arlington, but didn't build up at all. Looks like maybe it's starting up again now, but those without excellent eyesight would never notice it's snowing at all.

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  7. How about for some good old rain, maybe a little wind? The now finished November and start to December has been one of the biggest yawners in recent memory.

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  8. Past 3 days in NW Bellingham have averaged below freezing. Max temp today was 39.5F. Max temp for November was 56.8F, min temp was 21.8F. There were 10 days with min temps at or below freezing, 10 days with min temps at or above 40F, 8 days with max temps at or above 55F and 10 days with max temps at or below 49F. Average temp for the month was 43.1F. 30-year average November temp at BLI is 43.2F. So, overall, a very average month with regard to temperature but very dry with only around 35% of average precip.

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    Replies
    1. My impression is that temperature-wise Seattle has been pretty much average since last March. The link posted above seems to back this impression with some exceptions to the upside and some exceptions to the down side. Any other analysis to back or contradict this? Have the average monthly highs and lows been higher or lower than normal from last March on?

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    2. The period between March and the present seems to have been relatively average at my location, though, when compared to the long-term averages, precipitation has been somewhat less. My data resolution for the March-October period consists only of monthly max and min temps. Summertime monthly max and min temps were consistent with the past 5 years, while spring and fall temps were lower than in recent years - though that's not saying much since spring and fall have been particularly warm recently.

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    3. I copy-pasted monthly averages for January to November 2019 from the link given by MAC above. The values were measured at Sea/Tac. Left two columns are the observed values ("High"/"Low") while the right two columns are the average (normal) values ("High Av"/"Low Av"). October was a bit cooler than normal while November a bit warmer (only slightly for the low). September low was a bit higher but the high a bit lower than the average. All other months were rather warmer than average with the exception of February (and March low only slightly warmer). I wonder whether El NiƱo has had any influence on the temperatures this year.

      Low High Av Low Av HIgh

      January: 38.9 51.1 36.8 47.3
      February: 31.6 41.8 37.0 49.9
      March: 39.7 57.2 39.4 53.8
      April: 45.6 59.3 42.2 58.5
      May: 51.2 69.7 47.4 64.7
      June: 53.9 73.4 51.9 70.0
      July: 58.5 76.5 55.6 75.7
      August: 59.9 78.3 55.9 76.3
      September: 56.1 69.4 52.1 70.6
      October: 43.7 58.0 45.9 59.7
      November: 40.7 52.6 40.0 50.9

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    4. Now that I have a higher resolution data logger, it will be interesting to compile and analyze my future records. My period of record at my location is only just over 4-years, so I compare with records from BLI and temperatures are usually quite similar - sometimes slightly warmer or cooler - though my location is almost certainly drier.

      Delete
  9. MAC,

    Since you referred to me without addressing me, I'll break the ice: Hello! How are you? I am well. I'm assuming you have PWS. What, if anything, are you measuring with at your location?

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  10. Hopefully Old Man Winter isn't snoring away in front of the TV while watching re-runs of Matlock. The past month alone was enough to put anyone to sleep. As much as many would prefer endless sun, a little variety in the weather dept around here would be welcomed with open arms.

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  11. The average November daily max temp at my location in NW Bellingham, 1.5mi SE of BLI, was 49F and the average daily min temp was 35.9F. The 30-year average daily max temp for November at BLI is 49.7F and the average daily min temp is 36.7F. I measured 1.81" of precip at my location and the 30-year, monthly average for November at BLI is 5.8".

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  12. Correction: The average November daily maximum temperature at my location was 50.8F.

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  13. OK, so now where is the rain that we are supposed to be getting in spades this time of year??

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  14. "Since it takes about 1000 ft of above-freezing air to melt snow"

    I am curious to know whether and how the amount of humidity affects whether precipitation comes down as snow, besides how far above the surface the freezing level is.

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  15. Also, The average daily max temp at BLI in October was 56.8F and the average daily min temp was 41.9F. The 30-year average daily maximum for month is 57.9 and the average daily minimum is 41.6F. So, indeed, both October and November have featured temperatures slightly below the long-term average. The monthly maximum and minimum temperatures in both months were lower than those recorded in either month in at least the past 5 years.

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