December 2016 Observations and Model Discussion for the Pacific Northwest

[Deweydog]

Good potential for frozen lakes with the coming cold since it has been cold for so long already.

Ice Road Truckers - Lake Washington.

 

Coming Spring 2017 to The History Channel!

[Gradient Keeper]

I can still recall how stoically the arctic air limped in for that one.

 

One of these days we will get a real arctic front.

I can't wait for that. I mean, I can, it has just been awhile. 2008 blasted through pretty nice on the 13th. 2004 was probably the last great one I can recall.

[Jesse]

They're pretty rare down here.

Rare enough that never predicting them is the surest path to accuracy!

[Heavy Snow]

At face value from the 00z EURO Snow maps, it shows a widespread 1"-3" snowfall for PDX Metro for the New Years Arctic Front. Highest amounts approaching 2"-3" are Western Washington County, Scappoose/Kelso/Longview areas and Troutdale East. Even higher amounts approaching 6"+ extreme NE PDX Metro in Cowlitz County and areas just to the East of Camas/Washougal.

[Deweydog]

Rare enough that never predicting them is the surest path to accuracy!

Do u think there will be a strong Artic front on Sunday?

 

When do you think the last one actually occurred here?

[Jesse]

Do u think there will be a strong Artic front on Sunday?

 

When do you think the last one actually occurred here?

Oh man. It's been years.

[Deweydog]

Oh man. It's been years.

Problem is, it depends on your standards of what is considered a front in these situations. Lift associated with a sharp windshift and Arctic air south of Lewis County or so is extremely hard to come by.

[SilverFallsAndrew]

Most sub-freezing nights in a month at PDX since December 2009. 

[snow_wizard]

Amplify a ridge along 150-170 W (like in your signature images) and most of the time downstream development will cause a trough to dig along/just inland from the west coast. A bit of positive tilt to the ridge helps too. It's not so much that it's complicated for us to get cold, it's just not common to see a long-lived amplified block along 150-170 W at the same time the PV is on our side of the pole.

 

Snow on the other hand is fairly complicated, unless we are talking the typical overrunning transition snow event.

 

 

If the setup is amazing enough snow isn't that hard either.  Jan 1950 had snow on like half of the days in Seattle.  There are other old time winters where that was true as well.

[BLI snowman]

Do u think there will be a strong Artic front on Sunday?

 

When do you think the last one actually occurred here?

 

November 22-23, 2010 was pretty damned impressive all the way down to Portland, IMO.

[Jesse]

Most sub-freezing nights in a month at PDX since December 2009.

Good catch! I was thinking there have been a lot.

[SilverFallsAndrew]

At face value from the 00z EURO Snow maps, it shows a widespread 1"-3" snowfall for PDX Metro for the New Years Arctic Front. Highest amounts approaching 2"-3" are Western Washington County, Scappoose/Kelso/Longview areas and Troutdale. Even higher amounts approaching 6"+ extreme NE PDX Metro in Cowlitz County and Camas/Washougal areas. 

 

Sounds like the opposite of the WRF, it has almost nothing below 1000' for the metro area. 

[Deweydog]

November 22-23, 2010 was pretty damned impressive all the way down to Portland, IMO.

Definitely. Just no mechanism for widespread precip.

[Gradient Keeper]

I forgot to mention, the Gorge/Columbia Basin look to be snow covered going into the blast making us even colder.

[snow_wizard]

Ice Road Truckers - Lake Washington.

 

Coming Spring 2017 to The History Channel!

 

Fun times!

[IbrChris]

Virtually the entire week 2-week 6 period suggests below to well-below normal temps across the NW US on the 12/22 Euro Weeklies (latest run). Week 2 and 3 the center of the positive 500 mb anomaly is along 160 W. Week 4 it shifts to 150 W and the amplitude lessens...though still suggestive of cold N-NW flow. Week 5 still along 150 W but a bit of negative tilt into Alaska with the PNW in a N-NW flow. Week 6 the ridge retrogrades to 155-160 W and takes on a positive tilt while amplifying, suggesting a significant number of members would give us another arctic blast sometime late in Jan-early Feb.

 

What is astonishing is this pattern suggests to me that the entire month of January will be generally below normal...potentially significantly/strongly below normal.

[Gradient Keeper]

November 22-23, 2010 was pretty damned impressive all the way down to Portland, IMO.

Crap. I forgot that one. The rare N-NW blast. I was 11 degrees with that one.

[SilverFallsAndrew]

Good catch! I was thinking there have been a lot.

 

17 so far, which is pretty impressive for them. I only have 2 more than they do. Even more impressive on the season PDX has only two less than I do. Generally I average at least 2X as many sub-freezing minimums.

[Gradient Keeper]

Ice Road Truckers - Lake Washington.

 

Coming Spring 2017 to The History Channel!

I'd watch!

[BLI snowman]

If the setup is amazing enough snow isn't that hard either.  Jan 1950 had snow on like half of the days in Seattle.  There are other old time winters where that was true as well.

 

PDX actually had 28 days with snow falling in January 1950, twas a drippy and cloudy month, just with snow instead of our usual dreariness. 

 

 https://www.wunderground.com/history/airport/kpdx/1950/1/22/MonthlyHistory.html?&reqdb.zip=&reqdb.magic=&reqdb.wmo=

[MossMan]

What is left of the snow at work from Friday. Hopefully much more to come next week!

[Heavy Snow]

Sounds like the opposite of the WRF, it has almost nothing below 1000' for the metro area. 

 

I took a closer look and at the center of the city looks to be a dusting to 0.5" at the minimum, hard to tell from the gray color scheme. It does show 2" for Troutdale, 3" for Kelso and the bigger amounts in Cowlitz County and areas East of Troutdale/Camas/Washougal. Also 2" for Salem and even higher amounts as you get progressively East of there.

[IbrChris]

If the setup is amazing enough snow isn't that hard either.  Jan 1950 had snow on like half of the days in Seattle.  There are other old time winters where that was true as well

Complicated in our modern era.

[BLI snowman]

Definitely. Just no mechanism for widespread precip.

 

12/14/2008 and 2/12/1995 were the last really snowy traditional arctic fronts in the Portland metro. They're not super common but they used to be a lot more so. 

[snow_wizard]

17 so far, which is pretty impressive for them. I only have 2 more than they do. Even more impressive on the season PDX has only two less than I do. Generally I average at least 2X as many sub-freezing minimums.

 

SEA has only had 10.  Pretty lame, but their monthly average is respectable.

[snow_wizard]

The Canadian ensemble is the best I have ever seen for 12 days out.  Very strong cold signal for that range.

 

 

[MossMan]

Traffic looks a little rough up there at the moment.

http://images.wsdot.wa.gov/nw/005vc27650.jpg

http://images.wsdot.wa.gov/nw/005vc25494.jpg

http://images.wsdot.wa.gov/nw/005vc24625.jpg?1482781322511

[Heavy Snow]

Virtually the entire week 2-week 6 period suggests below to well-below normal temps across the NW US on the 12/22 Euro Weeklies (latest run). Week 2 and 3 the center of the positive 500 mb anomaly is along 160 W. Week 4 it shifts to 150 W and the amplitude lessens...though still suggestive of cold N-NW flow. Week 5 still along 150 W but a bit of negative tilt into Alaska with the PNW in a N-NW flow. Week 6 the ridge retrogrades to 155-160 W and takes on a positive tilt while amplifying, suggesting a significant number of members would give us another arctic blast sometime late in Jan-early Feb.

 

What is astonishing is this pattern suggests to me that the entire month of January will be generally below normal...potentially significantly/strongly below normal.

 

That's pretty incredible.

[Jesse]

Virtually the entire week 2-week 6 period suggests below to well-below normal temps across the NW US on the 12/22 Euro Weeklies (latest run). Week 2 and 3 the center of the positive 500 mb anomaly is along 160 W. Week 4 it shifts to 150 W and the amplitude lessens...though still suggestive of cold N-NW flow. Week 5 still along 150 W but a bit of negative tilt into Alaska with the PNW in a N-NW flow. Week 6 the ridge retrogrades to 155-160 W and takes on a positive tilt while amplifying, suggesting a significant number of members would give us another arctic blast sometime late in Jan-early Feb.

 

What is astonishing is this pattern suggests to me that the entire month of January will be generally below normal...potentially significantly/strongly below normal.

Seems too good to be true.

[Gradient Keeper]

Virtually the entire week 2-week 6 period suggests below to well-below normal temps across the NW US on the 12/22 Euro Weeklies (latest run). Week 2 and 3 the center of the positive 500 mb anomaly is along 160 W. Week 4 it shifts to 150 W and the amplitude lessens...though still suggestive of cold N-NW flow. Week 5 still along 150 W but a bit of negative tilt into Alaska with the PNW in a N-NW flow. Week 6 the ridge retrogrades to 155-160 W and takes on a positive tilt while amplifying, suggesting a significant number of members would give us another arctic blast sometime late in Jan-early Feb.

 

What is astonishing is this pattern suggests to me that the entire month of January will be generally below normal...potentially significantly/strongly below normal.

That is remarkable. Unbelievable potential if that unfolds. Thanks

[Jesse]

17 so far, which is pretty impressive for them. I only have 2 more than they do. Even more impressive on the season PDX has only two less than I do. Generally I average at least 2X as many sub-freezing minimums.

Good stuff. They could be tacking on at least another 2-3 in the next 5 days.

[SilverFallsAndrew]

12/14/2008 and 2/12/1995 were the last really snowy traditional arctic fronts in the Portland metro. They're not super common but they used to be a lot more so. 

 

The one in 2008 was somewhat odd. Very hit or miss. Some areas of the metro did very well others didn't. Woodburn got almost nothing, Salem and Silverton had 2-3", Albany had 3-4", Lebanon had nothing.

[IbrChris]

That is remarkable. Unbelievable potential if that unfolds. Thanks

Yeah I was surprised by it. The mean gives us highs below 40 for most of January...lows mostly below 30.

[Jesse]

November 22-23, 2010 was pretty damned impressive all the way down to Portland, IMO.

That was a pretty fun event. Would have been nice if it was snowier.

[Gradient Keeper]

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[Gradient Keeper]

Pattern sets up upstream over the GOA/AK in just 72-84 hours. That's not far away

[BLI snowman]

The one in 2008 was somewhat odd. Very hit or miss. Some areas of the metro did very well others didn't. Woodburn got almost nothing, Salem and Silverton had 2-3", Albany had 3-4", Lebanon had nothing.

 

Lots of downsloping and dry air slotting in there with that storm. Westside of the valley did much better. 

[FroYoBro]

Lots of downsloping and dry air slotting in there with that storm. Westside of the valley did much better. 

Yep. I did well in Tigard with that. 

[BLI snowman]

That was a pretty fun event. Would have been nice if it was snowier.

 

 Troutdale had some thundersnow, but that front was hauling a** so those dynamics were fleeting. 

[van city]

Very heavy snowfall here.