Some Snow?

Snapshot Ahh, the good times are back this evening with some good heavy rain showers in spots (right over Steve Pierce's home).  And now we have the possibility of snow to low elevations tomorrow night and Thursday.  I just had the studs taken off my
"snow car", luckily it's a 4 wheel drive that'll do fine in a few inches of snow!  For tonight…more showers.  For tomorrow…more showers.  A nice slug of moisture to our southwest keeps the showers going overnight.  It still looks like the heaviest precipitation will be from the Columbia River south. 

     Then a sharp cold front moves into Northwest Oregon tomorrow afternoon.  This is the leading edge of a very cold maritime polar airmass.  Arctic air is already beginning to spill out of British Columbia between Vancouver Island and the Queen Charlotte Islands.  So we get an upper-level low and a surface low spinning up near Northern Vancouver Island later tomorrow.  These both pass overhead Thursday.  00z models all seem to be in agreement now on the movement.  The surface low comes inland around Astoria as it fills Thursday morning.  It's a really cold airmass!  850mb temps are somewhere around -8 to -9 deg. C.  That's usually cold enough to get snow to sea level if you can get rid of a mixing wind.  We still have a light southerly flow up the Willamette Valley tomorrow evening and Thursday because the low is staying farther north, but it's not exactly a raging south wind.  Heavy precipitation intensity always helps in these situations, or is sometimes the key factor to getting snow to low elevations.  With the westerly flow, the areas west of I-5 may have lighter precip.  In general I don't see a ton of heavy showers.  The steadiest precipitation should be in that 4am-10am time period Thursday…then we dry out in the afternoon (and warm up of course). 

Put these all together and this is what I get:  I think it'll be tough to get significant snow (>1") here in the lowest elevations of Portland, but all of us should see at least a dusting in the morning Thursday.  I'd say 1-3"+ snow is a done deal at/above 1,000' anywhere in our region, and anywhere in SW Washington north of Vancouver.  The Coast is a big question mark…there's no reason we shouldn't be able to get snow to the beaches, unless the southerly breezy from Astoria south kills it for you folks.  We have 24 more hours to keep digesting information for this little event too.

Beyond Thursday, pretty quiet.  A new upper level trough develops offshore Saturday through Monday.  There are some deep surface lows that linger way out over the Pacific, but they aren't really going anywhere in a hurry, so they aren't a high wind threat for us…Mark Nelsen

12 Responses to Some Snow?

  1. Sandi (Wilsonville) says:

    Heavy rain shower going through. I can see blue sky off in the distance, but wind picked up and rain really coming down now.

  2. stevied (North Portland) says:

    Forks, WA
    11am report
    36 degrees and light rain
    brrrr

  3. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    46.8F here and had a heavy shower around 9:15ish that lasted for about 15mins. Now let’s see how much rain I picked up over night. *checks rain gauge*
    Looks like 0.16″ for me. Not the best amount.

  4. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    Glad we have an Astoria blogger here now. 🙂

  5. Andrew Johnson (Silverton) says:

    An interesting note is that Eugene picked up 1.65″ of rain yesterday.

  6. offroadjosh(7miles west of kalispell montana) says:

    forecasting 5-12inches of snow here=P
    Josh

  7. Jethro / Molalla says:

    06z NCEP GFS doesn’t show huge changes for Thursday, but maybe not as cold? Will anxiously wait for 12z…
    Saturday’s low isn’t as strong on the 06, but it brings the trajectory almost right over the top of us: http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/gfs/06/images/gfs_ten_102l.gif

  8. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    47.3F and 0.75 of rain up from 0.47. I’ll erase my gauge now.

  9. Tetraforce (2009-2010 The 1949-50 snow year equailvent) says:

    Billy where do you live in Astoria? I’ll check tomorrow for answers

  10. Tornado Aly (vancouver) says:

    Rob, I saw that low the last few runs you are speaking of as well. If it comes closer inland, it could be a decent windstorm. I don’t like how it meanders off the shore line though. Still have some days to keep an eye on it’s developments, perhaps it’ll move closer.

  11. HIO Phil (Punxsutawney) says:

    It looks like the 00z links SP posted has the low coming in a bit further north into S Washington to me. Like Mark mentioned, I’m wondering if we will have too much southerly wind for snow. Otherwise, I agree with Chris it will be a very cold column of air.

  12. poolsidemike says:

    first? no way! Go snow!

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