Forecasts: Confusing Early Next Week

I feel badly for the general public tonight…forecasters (including me) are being unusually wishy-washy about the Monday-Tuesday timeframe.  What a mess!  It’s somewhat unusual to have decent disagreement in the models in the 72-84 hour period (3-3.5 days).  I feel like I’ve been through an invasive TSA-style meteorological rub down the last 24 hours!

First, the next 3 days aren’t really a problem…cold showers tomorrow taper off Saturday, and maybe just a shower or dry on Sunday.  Snow level generally at/above 1,500′.

What’s the problem with Monday?

GFS, and now the NAM since that model runs to 84 hours, both bring moisture back overhead for showers Sunday night and into Monday.  Not a lot, but enough that we would see a couple inches of snow (maybe) if it’s cold enough.  The NAM at face value isn’t quite cold enough.  I notice it has a slightly rising freezing level by Monday morning with a southwesterly wind.  But it’s close nonetheless.

But the ECMWF stubbornly (for 2 or 3 runs now) keeps the action and moisture confined to a stronger wave that comes over us Monday afternoon and night.  It’s also slightly warmer at that time with light onshore flow…marginal.  So the ECMWF would just be dry Sunday night and Monday.

So how do you make a forecast for the public in this situation?  You just make up a bunch of fake weather words, mumble for 3 minutes, make a joke about the anchors…then go home.

Just kidding!  I chose the GFS and NAM approach and ignored the ECMWF.

Beyond that, looks dry as we head towards Thanksgiving.

Nice forecasts in the last post folks…some of you REALLY want it cold don’t you?  Watch out for wishcasting!

Chief Meteorologist Mark Nelsen

339 Responses to Forecasts: Confusing Early Next Week

  1. PDX Weather Nut says:

    Looks like some snow or mixed precip Sunday night/early Monday morning as the temperatures will be favorable and the moisture will be there.

  2. Snowfall warning for Metro Vancouver issued
    From Environment Canada

    Snowfall warning for Metro Vancouver continued
    5 to 10 cm of snow tonight.
    This is a warning that significant snowfall is expected or occurring in these regions. Monitor weather conditions..Listen for updated statements.
    A building Arctic ridge of high pressure over the British Columbia interior is producing strong outflow winds through the coastal valleys of the province and as a result cold air has pushed out to the coast. This cold air is forecast to combine with a low pressure system off Vancouver Island tonight to produce the first widespread snowfall of the season.
    5 to 10 cm of snow is forecast for metro Vancouver, East Vancouver Island, Greater Victoria and the Southern Gulf Islands with the highest amounts over higher terrain. Locally higher amounts are also possible along East Vancouver Island where outflow winds will pick up moisture over the strait of Georgia.
    The strong northeasterly outflow winds are expected to rise to 90 km/h with gusts to 110 over the Central Coast – coastal sections and up to 70 km/h with gusts to 90 over the southern sections of Howe Sound this evening.
    The Arctic airmass will also combine with the strong northeasterly outflow winds to produce low windchill values below minus 20 degrees over the inland sections of the north and central coast. The strong winds and cold windchills are expected to moderate later Saturday as the Arctic ridge and the pacific low weaken.

  3. Andrew Johnson says:

    I’m not biting on the “big snowstorm” bandwagon, but a widespread 1-3″ from PDX to EUG doesn’t seem unreasonable.

  4. Andrew Johnson says:

    Currently 44 with light rain and a breezy south wind here in Silverton. Kind of a nasty day out there. The way its supposed to be in Oregon in November!

    • Jake-(Gresham) says:

      Agreed!

    • Kyle says:

      Andrew I am glad your back in my little town of Silverton and I hope it’s for a long while this time!. 🙂

      Hope we get at least enough snow so the kids can have a 5 day Thanksgiving break or better yet THE WHOLE WEEK OFF!!.

  5. alohabb says:

    Does anyone have a good guess at temps for the next few days?

  6. Aloha Rainshadow says:

    18z is out to hour 84 now and is COLDER and QUICKER! 510 thickness to portland by 10pm Monday night and the -12 850mb line is JUST about to PDX by that time, BRRRRRRRRRRRRRR!!!!! Another colder trend!

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