Get Ready For The Coldest Week So Far!

It has been very mild December; in fact as of this evening it’s the 2nd warmest December on record at PDX!  But the last 3 days of the month are going to be totally different.  That’s Monday-Wednesday of next week.  Remember the yo-yo temperatures in November?  We saw rapid swings from warm to record cold to warm, and then back to cold at the end of the month.  We’re going to see that happen starting Monday again.

First, let’s get this weekend out-of-the-way.  A cool and wet system is dropping in overnight from the northwest.  This has a beautiful west/northwest flow behind it to pound the Cascades with what could be their best snow so far this season.   We really need it.  MarkSnow_MtHood_Totals  Although some snow has fallen this week and allowed Meadows/Timberline to open at least half their runs, we’re still way behind.  RPM_72_SNOW_00z  Our RPM forecast and WRF-GFS are about the same…showing a solid 12-18″ with possibly up to 2 feet in spots by the time we dry out Monday  Here in the lowlands that means mainly wet with a breezy south/southwest wind both days.

What’s changing Monday?  A strong ridge of high pressure magnifies quickly later Sunday-Monday over Alaska, sending a couple of upper-level disturbances plunging south along the West Coast.  The carve out a sharp upper-level trough over us which eventually ends up in Southern California later Tuesday/Wednesday. gfs_500mb_4pmMonday That is the view at 500mb (~18,000′) Monday evening.  What happens down below is even more interesting.  A HUGE surface high pressure area drops south through Western Canada and into western half of the USA.  Take a look at that monster Monday evening at 10pm:  gfs_1060mb_Mon10pm

It’s covering about a third of the country already with a central pressure right around 1060 millibars…expect your home barometer to skyrocket early in the upcoming week!  Of course cold high pressure to the north and east means gusty northeast wind for ALL OF US (not just in the Gorge) later Monday-Wednesday…probably not as strong as the damaging northeast wind in mid-November, but it’ll still turn windy and cold starting late Monday.

There is a slight chance that as the cold air starts arriving from the east Monday we’ll still have some showers around that could be mainly snow.  But almost always in this situation the cold air slowly trickles in (at first) while skies clear…as a result don’t get your hopes up for any sort of snow Monday.

How cold is it going to get?  One clue is in the 850 mb temps.  Models have been pretty consistent showing -8 to -10 over the northern Willamette Valley.  Seems that with sunshine and easterly well-mixed wind Tuesday we would see high temps around 35-40.  But, check out how cold it is up against the east slopes of the Cascades:  gfs_950_10pmMon

That -15 to -17 celsius at 5,000′ means the ski areas will be in the upper single digits or low teens at best late Monday through Tuesday…Brrrr!  That cold air will be funneled over the Cascades and through the Gorge, cooling us even further.  As a result I think we’ll only be around freezing or just a few degrees above on Tuesday, Wednesday, and New Year’s Day.  And in this pattern there is no obvious warming coming from the west or south, so the airmass will only slowly modify.

I’d tell you to wrap your pipes and sensitive plants, but it was cold twice in November so I assume you already have done that.

Is this going to be a one-shot deal?  Not sure yet.  The 12z ECMWF said YES, any cold air about 9-10 days from now will be diverted to the east or stay up north.  tseries_850t_000-360_Portland  The 12z GFS wasn’t so sure…you can see several ensemble members showing another cold shot.

tseries_850t_000-384_Portland

We’ll have to wait and see.  But for now the screaming message is that our coldest weather so far this cold season is on the way for Tuesday-Thursday.   2014 is going to go out cold!

I’ll probably post again Sunday evening since I’m working again.  But don’t worry about me, I already spent 1/2 hour this evening figuring out which days next summer I’ll take off to make up for it…

Chief Meteorologist Mark Nelsen

177 Responses to Get Ready For The Coldest Week So Far!

  1. David B. says:

    Wind shifting to NNE and dew point falling at Bellingham now…

  2. No Snow says:

    Bust-O-Rama.

  3. Jason Hougak says:

    Give me a 💣 I’m going 💥 these blasted 💻 models the the 🌙! The 00Z erased any precip out until Sunday, I think these models are celebrating 🎉New Years early with a little too much 🍺🍷! Goes to show you there’s a lot of uncertainty here, but it’s the fun that counts. Going🎿@ Tline tomorrow with my daughter in the amazing ❄️ the mountain has gotten, 49″ base!
    http://wxweb.meteostar.com/sample/sample.shtml?text=KTTD

  4. This next update Mark posts will either make or break our dreams…

    • Eugene Dave says:

      If there was anything interesting other than cold temps headed our way, it would have been posted already. Get ready for cold, wind, and nothing else.

    • Boydo3 N. Albany elev. just under 500' says:

      Dave’s right. Gonna be crispy cold with SUN!! A nice break from the gray, wet, gloom.

  5. David B. says:

    No Fraser outflow evident at Bellingham yet. Dew point at Hope has slipped below freezing and winds are picking up, but temp is still above freezing and dew point is not super-low yet there. So the event seems to be starting, but it’s definitely in its infancy.

    38 degree rain here on Bainbridge Island presently. If Bellingham was in the outflow and below freezing already, I’d be optimistic about seeing a dusting of snow on the ground tomorrow, but with the outflow taking its time to develop I think there’s slim chance of that this time.

  6. pappoose in scappoose says:

    NATIONAL WEATHER SERVICE PORTLAND OR
    827 PM PST SUN DEC 28 2014

    OF MORE IMPORTANCE IS THE DEVELOPING EAST WIND EVENT. THIS LOOKS LIKE A WIDESPREAD EVENT UP AND OVER THE CASCADES AND COAST RANGE AND
    IMPACTING THE DOWNSTREAM VALLEYS AND COAST. THE WINDS WILL INCREASE MONDAY AFTERNOON…AND REACH THEIR PEAK MONDAY NIGHT AND TUESDAY.
    THIS LOOKS MUCH LIKE THE DOWNSLOPE EAST WINDSTORMS WE HAD IN OCTOBER
    AND MID NOVEMBER…AND WIND SPEEDS COULD GET CLOSE TO THOSE VALUES. LEAVES ARE MOSTLY OFF THE TREES…BUT SOME POWER DISRUPTIONS WILL
    AGAIN BE POSSIBLE. HAVE ISSUED A HIGH WIND WATCH FOR THE PORTLAND AND VANCOUVER METRO AREAS AND ADJACENT CASCADE FOOTHILLS FOR MONDAY NIGHT
    AND TUESDAY. THE WINDS WILL BE AIDED BY THE STRONG NORTHEAST FLOW ALOFT AS THE DISTURBANCE MENTIONED ABOVE MOVES THROUGH. WINDS SHOULD
    EASE BY TUESDAY EVENING. NEVERTHELESS…THE DRY AND COLD AIR MASS AND SOME EAST WINDS WILL CONTINUE THROUGH WEDNESDAY AND PROBABLY INTO
    THURSDAY.

  7. High Desert Mat says:

    Brian and dharma are going on vacation together I think,,,,,if you know what I mean!!!!!! Lol

    • Clackamas County Jack says:

      Come on man really?

    • dharmabum says:

      Matty boy, it ain’t your typical vacation, you would be a sniveling cry baby half way through the trip, this is not your whimpy centeral oregon weather, this is experienced survival camping in the heart of Idaho winter. I’ll post pictures for you and your armchair ………I’m at a loss for words.

    • W7ENK says:

      No offense dharmabum, really, but I didn’t realize “experienced survival camping” involved internet connectivity. See, when I go out to the middle of no-mans land and play “survivor man” I actually remove the battery from my phone. I go places I don’t want Google or the government knowing where I am. Maybe I’m out there stockpiling food, weapons and ammunition in preparation for the zombie apocalypse? Maybe I’m just sitting around a campfire drinking beers, scratching myself and pi$$ing on trees?? Either way, I really enjoy the fact that one would need real-time satellite tracking in order to find me… something you seem to have forgotten. That’s how you play “survivor man”, survivor man.

  8. dharmabum says:

    I cannot believe Portland has such of group of pathetic weather bloggers, just the same old silly boring B.S day in, day out. Glad to be out of town for two weeks. Hoping the New year will bring some intelligence to the blog discussions. Too much to hope for wisdom also.

  9. Hey Mark why is it that whenever there’s a possible snowflake in the metro area you guys go to the west side of town?

    • Clackamas County Jack says:

      It does seem like they always run over there.

    • Hal in Aims says:

      except when the junior guy/gal gets to stand in front of the truck stop in Troutdale dodging burrito wrappers in the east wind wating for the first flake……….uh…snow flake…….

    • Mark says:

      Simple answer: KPTV is located on the west side of town. It is highly visible from Sunset/HWY 26, just before The Cornell Rd. Exit (if heading westbound).

      Thus, a quick 10 minute drive to park it on the Sylvan overpass is easiest, and most cost effective. No bias, just economics at work. If they were located in Gresham, they’d likely bolt up to Sandy to show off snow… Or something like that.

  10. High Desert Mat says:

    Hawks win tonight and get the number one seed, weather is turning colder with snow in the air now and more likely to come tonight/tomorrow. Maybe more next weekend. Happy New Year Everyone!!!!!

  11. JERAT416 says:

    Repeat of the 1989 cold snap, please!

  12. I dont see how any accumulatuion will be anywhere near the metro tonight. The moisture is already running out and it’s still 43 degrees in Portland.

  13. Sapo says:

    18z GFS is nice. Shows us getting hit with precipitation on the 7th, with upper air temperatures fluctuating from freezing to a couple degrees above…Could be some sort of wintry mix event if it actually occurred.

  14. So far i’m going to take everything in the 10 day forecast for a grain of salt.

  15. Hal in Aims says:

    thunder……..heavy rain/hail

  16. Some dark clouds to my north!

  17. Jake@BlueLake says:

    Nice little T-storm in Fairview. Couple good cracks and now hail.

  18. Max in Fairview says:

    Just had some lighting and thunder here in Fairview.

  19. Happy New Year Y’all!

  20. Jake@BlueLake says:

    Does anyone have the links or names of the Facebook pages that discuss our weather here and around Portland? Thanks a bunch, Happy New Year to you all! JJ

  21. WEATHERDAN says:

    So the NWS has Salem at 30 for a high on Tuesday and mostly cloudy with some freezing fog and North winds to 20 mph. Huh? There will be no inversion on Tuesday and we will have strong mixing winds with very low dewpoints. So fog is very unlikely. I think NWS stands for No way sensible. As for the models it sometimes seems that they do better 10 days than 2 days out. 10 days out you can spot a trend not an exact forecast. But 2 days out things change so fast even 1 degree can make a big difference in observed weather. As for this week it should be cold but how cold. We should have precip but which kind. 5 degrees difference in July is no big deal. 90-95 is hot no matter what. But with 30-35 it is a big deal. 30 means snow or zr and 35 means rain. And it seems a lot of the time the models just aren’t that precise. So as far as temps and precip go this week we shall see what we shall see. Go Steelers. Peace.

  22. JohnD says:

    In our marine climate it is simply really hard to muster a bonafide, lasting winter rather pattern. The “problem” is that it “can” happen and once in a great while “does”–e.g. last February. Certainly there have been many historical periods where it was more “when” than “if” a winter storm would roll around in any given season. For those of us with winter weather passion, ther is always the attendant frustration. Usually our flirts–as now–end up not amounting to much. While at the same time we have fairly fresh memories of the last time that it did. Plus we also live close to where winter weather does happen much more frequently. Right now I am voting for the GOLU model. So many variables upstream at this point–and changing all the time. One thing is obvious, at least it will be pretty cold for a couple of days coming up..At least that is something!

    • PurpleHaze says:

      Try moving to Washington DC! Modern history snowfall has been very minimum except for 2008 which featured two major snowstorms one in December and the other in Feb but in between those major snow events was very boring.

      Our winter last year was VERY boring in between the Artic event and the Feb snowfall.

  23. Jason Hougak says:

    12Z puts next Tuesdays low pressure system off the coast from the mouth of the Columbia River. I think models will underestimate the cold air transported through the gorge. Just like 2004’s ice storm, which lasted days longer than thought.

    • High Desert Mat says:

      Jason, in 2004 the lows were heading inland to the south of PDX.

    • I don’t think anything special is going to happen out of this, maybe a little ZR and thats it.

    • MasterNate says:

      I agree with Boring. Not a direct hit, just another back door event but better than the first 2 in November.

    • And even if precipitation decides to filter in, the cold/cool air will probably be too shallow for snow to even form in the atmosphere. On top of that, the shallow cold air may not even be cold enough for ZR or snow anyways.

    • chris s says:

      Mat, initially yes the lows were going a bit south… but if you pull up the historical maps for Jan 3rd thru about the 10th, you will see that is not the case at all. Nobody really knows whats going to happen next weekend, as was the case back in Jan of 04′, when every met on tv and National weather circus warmed us up right away, only to be wrong day in and day out. I think we should all sit back and ignore the models for next few days, as i think the wild swings just in the past 36 hours on them should be enough to realize they dont have any sort of handle on it at all. Just my .02 cents. 🙂

    • Sapo says:

      12z ECMWF was bad. This could get interesting if the GFS verified, but yes this may not be a big snowstorm but I think that if it happens it will be better than the November stuff.

    • Brian Leroy says:

      12z gfs parallel lines with the 12z euro also.

    • Brian Leroy says:

      Cliff mass is not on board with any arctic air coming just sun and norm temps.

    • Garron near Washington square says:

      The last 24 hours or so it’s looking increasingly less and less likely for a snow storm Jan. 5-7th. The ensemble member’s temps. have jumped from -7 to around -2 this morning on a majority of the models. You need around -7 or colder to get anything meaningful for a snow event. The low forecast for next Friday morning looks to push most of the arctic energy east, while at the same time our high pressure flattens out cutting us off from the cold energy source. MAYBE another flirt with frozen precip will be if the low comes in early enough in the morning on Friday, but with the winds changing from NNE to South, it would be a brief transition.
      It COULD totally flip on the next runs, but the trend is starting to not be our friend IMO…The ECMWF model continues to keep the high pressure strong and pushing the low north of our area, so stay tuned. I still think our chances for snow are best Monday morning as a secondary front may take longer for the precip to end, and Friday morning.

    • Brian Leroy says:

      They need to do away with ncep op gfs since the gfs parallel is much more accurate, and it’s still in conflict with each other per 18z runs.

%d bloggers like this: