Back to the Future

Posted by Rufus La Lone on

Monday December 19
Patrons that have brought their Mug to the counter here for several years know that often model projections swing back-n-forth, meaning that what was projected earlier oft ends up being the actual weather event at the present.  Such is the case with the outlook for the end of this week.   Snow, sleet, freezing rain is again likely on Thu & Fri Dec 22, 23.  Here ya go —
The modified Arctic Front has arrived across the far NW WA / BC area (temperature in Bellingham this morning dropped to 16, with snow yesterday and last night across much of the Puget Sound.  The White is back.  Patrons in NW WA can expect additional snow over the next couple of days (inches!), as a Low moves onshore to the south.  It will remain cold.  
For Patrons in OR, the front has been delayed (a common aspect of these patterns) until early this week.  By Wednesday, eastern basins in OR, as well as valley temps will be quite cold (negative F in eastern WA, close to that for the usual cold locations in OR).  As such, the east wind out of the Columbia Gorge will ROAR - as strong as 80-100 mph at Crown Point - Thu through Fri Dec 22,23.  The cold air settles in on Wed.  Dry & cold for western OR.  The ‘depth’ of Arctic Air east of the Cascades should be enough to push subfreezing temps across the Willamette Valley / north OR coast by Thu the 22nd.  
This forecast, if verified, is the Back to the Future one, as earlier expectations called for a very MESSY WINTER EVENT to end this week, right at the time so many folks are traveling for the holiday weekend.  Why?  With the cold air settling in at the surface, west of the Cascades, any moisture riding up over that cold air will set off frozen precip issues.  The forecast for Thu into Fri is complicated, so please heed Nat’l Wx Service watches & warnings that are likely to be posted soon.
We will forecast the possibility for all three forms of frozen precipitation - snow, sleet, freezing rain - depending on your location as a warm front moves onshore by sometime Thu.  The farther south one is in the PNW, the less likely to have any or all three types of frozen precip (unless in the mountains).  Therefore, for:
  1. Eugene area north to Albany, the surface air flow could turn from the south early enough to usher in rain, or light freezing rain first, then all rain.  Depending on how cold it gets, rain/snow mix is an outside chance, but models push a ‘finger of warm’ air into the mid-level atmosphere, which melts snow flakes and causes freezing rain, if surface temps are below 33.  You know the drill.  Plan on freezing rain Thu night.
  2. Areas north of Salem, the chance two of the three, or at least freezing rain, from the event coming is more likely.  Gorge winds could keep SNOW as the type of frozen precip arriving first, before progressing to sleet or freezing rain, THEN rain if the moisture source continues.  The quicker the front approaches, the less issue with snow.  East Portland into the Gorge will be quite wintery.  Travel after dark on Thu and into Fri will be dangerous.
  3. SW WA up into the southern Puget Sound region, it will be possible to get all three forms of frozen water before any rain.  Right now, it may remain at or below freezing as the storm passes.  In other words, it may not rain until Sat.  Travel will be impacted.
  4. Seattle north to BC,  Patrons could experience another significant shot of snow before sleet and then freezing rain on top of those layers of frozen water.  Travel will be dangerous; expect delays in air travel.
    Christmas Eve / Day.  The winter event should be over (except for east of the Cascades & the mountains).  RAIN will rapidly move in on Saturday for everyone.  RAIN will be in play on Christmas Day, as well.  Forget the dry holiday we expected a week ago.  It will be quite WET.  But wait, there’s more.
    Week after Christmas heading into the New Year is modeled to bring on another high wx impact event.  HEAVY RAINFALL.  Models for the past week have been charting a series of WET Pacific storms moving onshore right after another through the entire week.  The ‘jet stream’ by Wed Dec 28 will be extremely strong and aimed right at western OR.  Multiple inches of rain are possible for BC, western WA, western OR and northern CA as the last days of 2022 click by.  
    Let’s get through the Christmas period first, then we’ll deal with the water issues.  Just be ready if you live in flood prone locations as a big slam-bam goodbye twenty-twenty-two looks probable.  Yikes.
    “At Christmas consider not so much the gift of a friend but the friendship of the giver."
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