Tough Snow Forecast

SnapshotSo here’s what I’m thinking for the big "storm" tomorrow.  The basic idea is that we are all going to see some white, like we did on Christmas Day, through the morning hours.  Assuming the precipitation falls at a significant clip, which it should, all of us should see some white on the ground as well.  That said, increasing southerly flow in the 1,000-2,000′ elevation (20-30 mph) is sure going to be fighting against the precipitation rate.  So this should be a snow event where elevation makes a tremendous difference in snow totals.  Notice I’m forecasting possibly 2-4" at the top of the West Hills, but maybe almost nothing down IN Portland "proper".  Put another way, if you want to go sledding tomorrow or build a snowman, I think you will probably need to be at least 500′ or above.
or another…I doubt we’ll have any travel issues on the main city roads/highways.  Only in the higher hills will you find slush and then totally snow covered roads as you get well above 500′.

The reason I don’t think we’ll have the 3-7" the NWS is forecasting are these:

1.  Airmass is pretty much the same (except for overnight cooling tonight) overhead that we had Christmas Day.  That was also a very marginal event, but produced a widespread dusting with only about 1 hour of steady moderate precip. 
2.  Precipitation appears to be quite light until early afternoon, not the real heavy stuff that could drag the 32 degree line down to the valley floor.  Yes, the precip. gets quite a bit heavier as the cold front approaches mid-late afternoon, but much stronger southerly wind gets going above the surface at the same time (notice 00z MM5-Cross-Section).
3.  Our RPM model here says the same thing…slightly too warm, especially after 10am. 

If we don’t get sustained and moderate precip in the morning, then we could end up with nothing in the city…hopefully that won’t be the case.

I think we all agree on this…it’s going to be a dramatic warmup with a gusty southerly wind after 4pm.  The snow level jumps up to 2,000′ and then stays above there until early Sunday.

Mark Nelsen

968 Responses to Tough Snow Forecast

  1. uh-oh…starting to mix with rain here….33.1…:(

  2. Austin-Ridgefield says:

    All in all Mark Nelson did great he was pretty much right about everything a trace-inch was the right call I will never doubt Mark Nelson again good job Mark Nelson wouldn’t want anyother meteoroligist.

  3. Austin-Ridgefield says:

    Know it is really picking up and they are big flakes to guess it is not over just yet its final stand.

  4. Austin-Ridgefield says:

    cdlose call back to all snow but really light guess it is ending.

  5. timothy says:

    east wind picking up im cooling down and a n.w. flow i think things might get interesting tonight…anyone seeing the moisture coming down from the north ?hmmmmm. i think things are going south more than they thought it might not warm up much…any thoughts rob anyone…

  6. Austin-Ridgefield says:

    NOOOOOOOOOOOOOOO!!!! This can’t be happening to us northeners it is starting to Mix with rain I say 60%snow and 40% rain:(

  7. J.R. says:

    that was fun

  8. Austin-Ridgefield says:

    Jacob, If we would have had none of this snow melt I am sure we could have had atleast 4 inches but it wasn’t cold enough to bad.

  9. Jethro, 5 miles S of Canby says:

    Oh would you two just go build a snowman or something and let the rest of us sulk in peace?!?!? 😉

  10. Austin-Ridgefield says:

    looks like the heaviest snow I have seen all day is about to hit me can’t wait:)

  11. jacob BPA says:

    Austin Snow is About to Get heavy

  12. Austin-Ridgefield says:

    The green on the radar is getting to close for my likings it needs to go back south where it came from salem can you take back your warm air please.

  13. J.R. on cell (sidekick LX) at work says:

    Lol at this car in front of us there is only snow in the middle its now raining and were stuck behind a 4 wheel drive car doing 15mph

  14. EA TTD says:

    Damn east wind is blowing harder now than it has all day. We must have JUST missed in East County. Timing is everything.

  15. Austin-Ridgefield says:

    Glad to see my town of Ridgefield made the snow totals as of 2PM on the post above.

  16. EA TTD says:

    We’ll warm up throughout the evening. Our afternoon high temp. might be at 8:00 tonight.

  17. Christiana in Beaverton (Baseline & 163rd) says:

    I have one question for the group: are we going to freeze tonight? If we do it is going to be a ice-skating rink over here.

  18. Christiana in Beaverton (Baseline & 163rd) says:

    I have one question for the group: are we going to freeze tonight? If we do it is going to be a ice-skating rink over here.

  19. Clinton says:

    Sorry, working on afternoon discussion and zones. Yes, snow level falling back to 1000 on Sat night, and down to 500 ft on Sunday. Probably a repeat on Sun of what we saw yesterday with low snow levels, and only local accumulations on valley IF you get stuck under a moderate or heavy shower.

  20. andy (in eugene) (now in portland) says:

    okay…clinton says snow showers down to 500ft on sunday, but mat and josh claim to have some info which tells a very different story…what gives?

  21. Austin-Ridgefield says:

    Is anyone else seeing snow below 500′ besides me at 289′?

  22. J.R. on cell (sidekick LX) at work says:

    Ahahah and were stuck lol

  23. Austin-Ridgefield says:

    Snow is picking up again moderate rate and flakes are getting bigger must be the back edge of the precip man was this fun I have had snow for 7 hours with out stopping although only 1 n 3/4 of snow stuck it is fun is the back edge the front that will come through or is there another batch of precip coming after this?

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