Cool and Wet Weather Ahead

October will end cooler than average for most of us in the region.  The temperature at PDX (53.5) will end up the coolest in 5 years.   Eugene will be the coolest since 1981.  Of course all that sunny weather means only about 1/2 of our normal rainfall.

Now November is our wettest month of the year on average here in Portland…5.63″ is the average.  And in accordance with that we get a much wetter weather pattern once we get past the 1st day of the month.

Several items of interest.  First is the surface low pressure system that tracks into the Strait of Juan de Fuca Saturday.  Models have slowed it down a bit, and the 00z GFS has pushed it a little farther south.  Still, gusts shouldn’t get much above 60 mph on the northern Oregon Coast and 35-45 mph here in the valleys.  It WILL be the strongest storm we’ve seen in a month though.  Wind should pick up nicely just before daybreak Saturday here in the Portland area.

Here’s the 00z WRF-GFS showing the low inland over Washington and the tight southerly pressure gradient:

slp.42.0000

Then, behind the cold front, strong and cold westerly flow behind the cold front will push a continuous stream of snow into the Cascades through sometime Sunday.  This will be the first dump of snow down to below pass elevations so far this season.  Government Camp could easily see 6-10″ from midday Saturday through midday Sunday.  A good 10-15″ more likely higher up in the mountains. Watch out travelling through the Cascades from near sunset Saturday through midday Sunday; expect mid-winter driving conditions!

MarkSnow_MtHoodFcst_2013

Another system comes through Monday afternoon through Tuesday, but snow levels will be rising to around 6,000′ briefly.  Then snow levels fall again the 2nd half of next week.  So the snow this weekend will be sticking around and we’ll see additional base accumulations next week.  Maybe most important is that we don’t see any sign of significantly warmer weather in the long-range.

Take a look at the 00z GFS ensemble chart:

tseries_850t_000-384_Portland

and the 12z ECMWF ensemble chart:

tseries_850t_000-360_Portland

Both show atmospheric temperatures over our area well below average through most of the foreseeable future (after tomorrow).  By the way, those of you planning to get on the “Wishcast Express”?  Based on the 00z operational GFS it appears to be cold enough for snow in Portland about 11 days from now.  But note the operational run was an outlier, the average of the ensembles is significantly warmer, but still below average.  We’ll see…

Chief Meteorologist Mark Nelsen

46 Responses to Cool and Wet Weather Ahead

  1. Some interesting predictions down below for max gusts from this low. 00z WRF-GFS is suggesting this will be a WA/OR coast and Puget Sound event. Realistic peak gusts appear to be ~35 mph for SLE to MMV/UAO, and closer to ~30 mph for PDX proper.

    Here’s the PDX time-height section: http://www.atmos.washington.edu/mm5rt/rt/showtimeheight_d2.cgi?initmodel=GFS&yyyymmddhh=current_gfs&loc=kpdx&locname=Portland,OR&latlon=45.59N,122.59W

    And here’s UAO: http://www.atmos.washington.edu/mm5rt/rt/showtimeheight_d2.cgi?initmodel=GFS&yyyymmddhh=current_gfs&loc=kuao&locname=Aurora,OR&latlon=45.25N,122.76W

  2. JJ78259 says:

    November 1st in San Antonio 86 and sunny not to shabby for the old Milwaukie boy. Still really feels like vacation. Kind of a weird feeling. The evening with friends over with a warm breeze going on outside is just amazing.

  3. Kenny says:

    The new 00z WRF GFS shows a 19mb to 20mb PDX – BLI gradient.

  4. High Desert Mat says:

    +1 for the 12z Euro. Looks good long term. Cold air moves this side of pole. Into Alaska as well. Plus it actually moved it up a day from what it was doing yesterday. Long ways out but encouraging nonetheless.

  5. Kenny says:

    My first initial thoughts on the 18z GFS is this: L pressure from the west and H pressure to the east. 850 temps are borderline but if we get offshore flow those to the north side of where the L tracks will get snow.

  6. Kenny says:

    The new 12z EURO is another step in the right direction. It shows a L pressure system dropping from the north along our coastline. At hour 216 it shows great promise as the L is just north of Vancouver Island. Then out to hour 240, the L moves down but the arctic air seems to stall in Canada. Eventually this arctic air will drop down, I’m highly confident of this. You will see that in the 216 to 240 time frame, the winds switch to a more northerly flow at 240. Again notice what I said yesterday that the -5C to -10C temps pour out over to the ocean, this means the arctic air is not sliding east, rather it is making its way down to us. If the models show this L dropping down, this will open the gates for the arctic air to come down. My optimism from the tremendous 00z GFS run last night is still there.

  7. schmit44 says:

    OCTOBER 2013 WEATHER CONTEST FINAL STANDINGS (OFFICIAL)
    Congrats to Andrew Greenhalgh-Johnson on his 3rd title. This was the closest race to the finish ever in a contest. Had Portland achieved a high of 59 yesterday instead of 60, Yev would have won his first contest. Click below link to see rankings.

  8. pappoose in scappoose says:

    OVERALL SIGNS FOR THIS SYSTEM REMAIN CONFUSED…

    NATIONAL WEATHER SERVICE PORTLAND OR
    900 AM PDT FRI NOV 1 2013

    THERE REMAINS A CONSIDERABLE AMOUNT OF UNCERTAINTY WITH THE LOW EXPECTED TO MOVE ONSHORE LATE TONIGHT OR SAT MORNING. THE NORMALLY MORE TRUSTWORTHY ECMWF HAS SEEN A LOT OF FLUCTUATION IN ITS SOLUTION WITH THE SURFACE LOW IN THE PAST 24 HOURS…BUT THE PAST TWO RUNS HAVE POINTED TOWARDS A DEEPER STRONGER AND MORE SOUTHERLY TRACK THAN THE MORE CONSISTENT GFS AND GEM SOLUTIONS. SATELLITE PICTURES DID SHOW SOME SIGNS OF A DEEPENING LOW OUT NEAR 44N 142W…BUT MODELS HAVE BEEN RATHER CONSERVATIVE ON JET STREAM SPEED ESTIMATES WHICH MAY LIMIT THE DEEPENING POTENTIAL OF THE STORM. OVERALL SIGNS FOR THIS SYSTEM REMAIN CONFUSED…BUT THE NET EFFECTS BETWEEN THE ECMWF AND OTHER MODELS ARE FAIRLY SIGNIFICANT AS THE ECWMF WOULD SUGGEST
    POTENTIAL FOR STRONG WINDS NOT JUST ON THE COAST BUT INTO THE NORTHERN INTERIOR. IN ADDITION TO THE POTENTIAL FOR STRONG S WINDS AHEAD OF THE FRONT…BOTH GFS AND ECWMF IMPLY STRONG NW WINDS BEHIND THE LOW. FOR NOW GIVEN THE CONSIDERABLE UNCERTAINTIES WILL CONSERVATIVELY ADD HIGH WIND WATCHES FOR THE S WA AND N OREGON COASTS FOR LATE TONIGHT INTO SAT.

  9. cgavic says:

    Sunny in sandy w/currently 45 degs

  10. pappoose in scappoose says:

    Major Blow On Saturday

    “Winds are coming on Saturday…yes, with some rain as well. And something else, something white.”

    http://cliffmass.blogspot.com/2013/10/major-blow-on-saturday.html

  11. Ryan (Walnut Grove) says:

    I do like the one ensemble member that rockets south of -10C around the 15th.

  12. pappoose in scappoose says:

    Wishcast Express? I’m definitely in! All ABOARD!

  13. schmit44 says:

    10/31/2013 Oregon (All) Temperature Summary

    Warmest:
    High:71 at AGNESS2( 247 ft) & ILLINOIS VALLEY(1389 ft)
    Low: 52 at JUNIPR(359 ft) & RUFUS(185 ft) & DUNES1(173 ft) & LINCON Lincoln C(187 ft)

    Coldest:
    High:36 at POINT PROM II(6607 ft)
    Low: 17 at Worden (4080 ft )

    Largest Diurnal Change: 46 degrees
    Worden (63/17 ) (4080 ft )

    Heaviest Rainfall:
    0.47″ at BEND WATERSHED(5330ft)
    0.33″ at BLACK MTN RIDGE(4965ft)
    0.32″ at RIDDLE MTN.(6352ft)

  14. Kenny says:

    The new 00z EURO is still good long term. The only difference from the 00z GFS is that the arctic air is still up in Canada. The potential for the arctic air to slide down is still there, I see no warming. Have a good night.

  15. Greg Carstens says:

    Interesting Mark

    A few weeks ago on the Facebook groups I talked about the potential for a snow situation to materialize after all the blocking we recently had up here in Tacoma. Perhaps that thought will come to fruition. Oh how I hope so and I am thinking about purchasing my ticket for the Wishcast Express soon.

    Interestingly the analogs once again showed November 1978 today and that was a very good month for snow especially in the South Sound when Olympia logged in 14.8 inches of snowfall that month.

    If it does snow here in November it will be the first snowfall for my Tacoma since November 2010 when I got 5 inches here in my yard. I wound up with 16.2 inches for the whole season.

  16. High Desert Mat says:

    Who is this new Kenny guy? Seems like Jacob BPA. No?

  17. TracyEllen Carson Webb says:

    SNOW!

  18. TygrrQueen says:

    Praying for snow!! =D

  19. Kenny says:

    Of course the ensembles will show many different outcomes in the long term. Until the ECMWF/EURO operational tell me otherwise, I am not at the least concerned.

  20. Kenny says:

    I’m in! Trust me when I say the 00z EURO tonight will show arctic air.

  21. Rob - Southeast Portland says:

    1st!

    YOU IN!

  22. Rob - Southeast Portland says:

    Haha
    “ALL ABOARD!!”

  23. Longview - 400 ft says:

    A chance for snow here in the valley over a week from now? Wow!!

    Here’s wishing!!!

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