Snowflakes on Your Weather App? Here’s What I’m Seeing For Thanksgiving Week

6pm Wednesday…

Am I getting old, or does it seem like a warm sunshine and temps in the 70s was just a few weeks ago?  Time is flying…

Forget about that warm stuff; it appears that winter is going to move in quickly over the next two weeks in the Pacific Northwest.

First, those weather apps.  This is what Brian MacMillan’s iPhone app showed today

iphone snow JPG

I use the FOX12 Oregon app which does not show lowland snow.  Keep in mind these apps are automated with no human intervention; although that isn’t as shocking as it was just five years ago.  I bet within 10 years most weather forecasting will be automated.  We’re not there yet but computer modeling is getting better.

Weather App Snow Forecasts

So what is going on next week?  I think SOMETHING is up with respect to cold and/or lowland frozen precipitation in the next 10+ days.  But it’s far too early to pin down any sort of details.  Our seven day forecast is snow-free right now, but it’s that time of year to start paying close attention to the forecast.

First, we have beautiful weather for three more days.  East wind keeps us mainly cloud/fog free through Saturday.  A warm upper-level ridge of high pressure keeps storms away and temperatures mild.

ECM_FRI22

By Sunday the flow overhead turns westerly and cools a bit.  Nothing too exciting, but we’ll likely get some light rain out of the first system.

ecm_sun24

But look at the change by next Wednesday!

ecm_wed27

A cold upper-level trough drops in over the western USA.  It’s still there the Saturday after Thanksgiving; the following is from the 18z GFS model.  A warm upper-level ridge into southern Alaska and a cold trough over the Pacific Northwest.  This is a very chilly weather pattern for us; historically a good setup for lowland snow west of the Cascades.

 

gfs_sat30

Look at the drop in temps the next 10+ days from the ECMWF model.  Forget highs near 60 like today.  Get used to 40s, which is typical mid-winter stuff for us.

ecmwf-operational-KPDX-daily_tmin_tmax_ecmwf-4251200

We have to see a specific placement of surface low pressure, wind direction, and precipitation; but snow CAN make it to sea-level with this setup.  Models have been all over the place the past few days on details.  On Sunday night the ECMWF model produced a snowstorm with 5-15″ snow in the metro area next Wednesday.  Last night the ECMWF brought a deep low into Central Oregon, dumping 2-6″ snow in the south Willamette Valley.  Today’s ECMWF (for example) doesn’t bring any snow west of the Cascades (other than flurries) because it’s much drier.  The latest 18z GFS brings snow into some of the lowlands on Black Friday and Saturday.    You get the idea…

Because of these wild run-to-run gyrations we use “ensemble forecasting”.  The ECMWF model is also run 51 times at a lower resolution.  A graphic showing each of those 51 members (horizontal lines) below shows about 6 of those 51 members produces notable snow (over 1″) in the metro area (Aurora) through Thanksgiving Weekend

ecmwf-ensemble-KUAO-indiv_snow_24-4251200

 

The GFS has 21 ensemble members, each going out two weeks.  Not much snow there, only 2 of those produce notable snow in the metro area through Thanksgiving Weekend

gfs-ensemble-all-KPDX-indiv_snow_24-4251200

To wrap it up…pay close attention to the forecast as we head toward Thanksgiving and beyond.  It’ll be turning colder.

One thing that’s also obvious, we sure aren’t heading into any sort of real wet/stormy pattern.   Just colder, and a little wetter.

I’m taking an extra day off this “weekend”, so probably no posts until Sunday.

Chief Meteorologist Mark Nelsen

160 Responses to Snowflakes on Your Weather App? Here’s What I’m Seeing For Thanksgiving Week

  1. JJ78259 says:

    Beautiful weather this weekend in San Antonio mid to upper 70’s and 80 tomorrow not bad for the end of November it makes it real easy to rake up some leaves in the yard I tell ya.

  2. WEATHERDAN says:

    If nothing else we have an interesting week before us. And perhaps the whole Winter. Anything is better than some borrring Winter that is usual around these parts. Think snow. Peace.

  3. Mr Realist says:

    Let’s hope that low deepens, gains massive strength and comes in around long beach!!!! Strong damaging south winds for Portland 🤞🤞🤞🤞🤞🤞🤞
    Come on guy’s think “strong damaging south winds “

  4. Roland Derksen says:

    Is Mark on holidays again? I’m looking forward to a new post- the weather is always in a state of change.(or about to change)

  5. Jason Hougak says:

    Waiting with anticipation. Cool and chilly with a stiff N breeze right now in the foothills.

    • Larry says:

      Glad i’m not the only one. Mark Nelsen’s analysis will make or break this hype fest, though the hype fest has already been battered from other meteorologists in the area.

  6. JohnD says:

    It will be great to read Mark’s analysis this evening.

  7. Tanis Leach says:

    0z Euro ensemble average has Eugene at 1 inch of snow Tuesday into Wednsday.

    • Jake in Gresham says:

      I think the cold gets here too late for Eugene but that’s just my 2 cents. One thing is for sure; over 2ft of snow for Mount Shasta with a low of 975mb is nothing to sneeze at!

      I’m really curious too if the Southern valley gets anything out of this. My bet is Roseburg down to Medford for a few inches (maybe) see’s something in the late hours.

      • Ken in Wood Village says:

        I’m thinking something big is going to happen. The 12Z Euro and GFS have been moving the Low a little further North now. The 12Z Euro has a 968mb Low approaching Southern Oregon Coast. That’s a strong Low and will produce a very strong South wind South of the Low but the Portland area will see a very strong East Wind Event. That will bring cold air from the Gorge into the Portland area. Not sure if there will be enough cold air to give us snow but the freezing level will be very low as it is so the possibility of snow is getting real. If the Low moves a little more North, then we have a major storm to deal with. We’ll see.

  8. Jake in Gresham says:

    Ice shards in Lake Michigan (b b bbbrrrrr, real cold right here):

  9. Kyleb_b says:

    Tue/Wed low keeps trending north on new Euro… If it keeps trending north at this pace it would bring precipitation to the metro area.

    • Mr Realist says:

      So, cold rain for Portland?? I bet everyone will be excited with that1😉

    • Joshua Lake Oswego says:

      Time to face the music, folks… it ain’t gonna snow. In fact, it’s barely going to rain in the next 10 days. Consider yourself extremely lucky if you see one stray snowflake early Wednesday morning. After that, consider yourself extremely lucky if you see one raindrop in the following week.

  10. runrain says:

    Why is NWS calling for Windy on Wednesday? Is that for an east wind? They were saying Very Windy, now Windy.

    • Mike says:

      I think it is because these current patterns are rather unusual and models don’t know what to make of them. I think we are leaning toward drought conditions if this pattern persists and don’t get back the normal set up of typical PNW weather.

      I saw horrible drought back in 1976-77 for the west coast. We don’t need that again.

      • Mr Realist says:

        I doubt we drought, it may be dry December and January. February will feature a lot of 37 degree rain.

  11. Mr Realist says:

    I know it is 8 days out, but the potential for a major icing is now looking like your shot at exciting weather 🤯🤯🤯🤯

  12. WEATHERDAN says:

    .39 in Salem since November 20th. That’s a record. Now more cold coming, then what. Very interesting eh what. Peace.

  13. Roland Derksen says:

    I’ve got 3.87 inches for the month so far- that’s not a record, but it’s way below normal for my location. We’ve still got more than a month left in the year, but I think 2019 will be my driest year since 1985. (provided, of course, I don’t see a December like last year).

  14. Mr Realist says:

    Massive Ice Storm coming December 2nd.

  15. Andrew says:

    Latest GFS position low a little bit more north than previous runs. I’ll be interested to see models tomorrow. Longer term shows a potential ice storm but I’m not putting much stock in that.

    • Ken in Wood Village says:

      I noticed that too about the GFS putting the first low a little further North. Going to what you are talking about the ice storm on the 1st. The 00Z Canadian (GEM or GDPS on pivotal) actually was showing this snow/ice storm last night. I was disregarding this because the Euro and GFS didn’t show it but now the GFS is showing it. Now it makes me wonder what may happen now on the 1st.

      Next week and weekend could be very interesting now.

  16. Evan -- Cedar Mill says:

    Hey guys! Just curious: What’s everyone’s favorite type of weather?!

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