Part I - January 2020 Weather Discussion for the PNW

[seattleweatherguy]

With that 850mb temp crash tomorrow night there could actually be some lowland snow if any C-Zones develop.

 

Will be waiting for it!

[Gradient Keeper]

Day 4

 

[bainbridgekid]

Far better than February. We had some snow and it was just barely cold enough. This is the real deal. Ideal timing nearing mid-January. C'mon it's not even close....

It was the 7th snowiest month in SEA's 72 year history so people up here obviously are going to have a very different view of the impressiveness of that month.

 

No real deep Arctic air though and it obviously didn't penetrate South particularly well.

[ShawniganLake]

Yeah, that first low level shot was pretty impressive especially considering upper level support wasn’t all that special. Seeing anything that cold up north would be a pretty big win.

There was a decent low level airmass out of the Fraser on the 3rd. Retreated pretty quickly but Abbotsford had a midnight high of 35F and had dropped to the teens by mid afternoon

[SilverFallsAndrew]

More evidence for the GFS solution. Great pattern and .95% or higher correlation score.

 

00z GFS Analog Composite

 

Day 6-10

 

Day 8-14

 

These analogs are a lot of cold onshore flow events...Not the "arctic blasts" people are hoping for. A couple were arctic, but most weren't. 

[snow_wizard]

Day 4 ECMWF is slightly better looking than day 5 on last night's run.

[Cloud]

My wife was stuck in that mass exodus!!! Got home around 5am.  Loved that storm, instant 2-3inches of snow with howling Northerly winds.  Power failed quickly as the storm blew through. 

I remembered I-5 was littered with abandoned cars that night. Crazy.

[Brian_in_Leavenworth]

I could be wrong on this but assuming confidence intervals for statistical estimation. 95% confidence interval based on a set of population, in this case the years shown.

Basically, if it falls within the 95% range or higher, there is a certain probability. So the correlation score measures the probability.

 

Not sure if this is what you're looking for.

So the score is how closely it matches past patterns.

[snow_wizard]

It was the 7th snowiest month in SEA's 72 year history so people up here obviously are going to have a very different view of the impressiveness of that month.

 

No real deep Arctic air though and it obviously didn't penetrate South particularly well.

 

I remember one day had a definite Fraser River wind at the beginning of the event, and then we had a cold east wind develop here the night of the 2nd snow event.  It snowed with temps in the mid 20s.  Pretty legit cold.

[Cloud]

So the score is how closely it matches past patterns.

Yes. 95% is almost certain. 

 

Edit: in the analogs composite posted. C=0.955, C=0.962 basically means 95.5% and 96.2% respectively. 

[TT-SEA]

Day 4 ECMWF is slightly better looking than day 5 on last night's run.

That trough offshore has been sure been de-balled over the last 2 00Z runs at that time.

[snow_wizard]

So the score is how closely it matches past patterns.

 

Exactly.  If a score falls below 80% you are talking about a pattern that is very hard to achieve as modeled.

[GHweatherChris]

I could care less about an arctic blast, don't need one of those to get a bunch of snow, IMO.

[Gradient Keeper]

Day 5

 

[SilverFallsAndrew]

Most people would be disappointed with a lot of the analogs there. 

 

Late December 2016 the models locked in an arctic solution. 850mb mean fell to like -13C, didn't quite turn out that way, but it did still get pretty cold and eventually lead to a nice overrunning event for the valley on the 7/8th. 

[TT-SEA]

I think the ECMWF is going to move towards the GFS on this run.

[Cloud]

Exactly.  If a score falls below 80% you are talking about a pattern that is very hard to achieve as modeled.

Once you fall outside of the 95% confidence interval, there are just way too many outliers to be included. Those will messed up the data. 

[snow_wizard]

At day 5 the high latitude piece of high pressure is still bonded to the mid latitude GOA ridge unlike last night's run at day 6.  A step toward the GFS!

[Gradient Keeper]

Day 5 past 4 runs

 

[Weiner Warrior]

1951 was decent for Oregon

[snow_wizard]

I could care less about an arctic blast, don't need one of those to get a bunch of snow, IMO.

 

I love the Arctic stuff.  Much more enjoyable and truly wintry.

[kokaneekidz]

So so true. The absolute best pattern is to have the outflow begin around Douglas Channel and wrap around YVR island and hit us. Then it picks up the proper moisture without having time to moderate . It is the best outcome for SNOW measured in feet vs inches . Otherwise we just end up with a quick hitter and then dry out for a week or so and sublimation melts it all. I prefer the former over the latter. Then if you aren't satisfied ask for a reload to do the dirty deal and crash us to zero farenheit once we have the goods firmly in the ground. Over and out //

 

 

I could care less about an arctic blast, don't need one of those to get a bunch of snow, IMO.

[snow_wizard]

Better Kona low on this run too.

[snow_wizard]

So so true. The absolute best pattern is to have the outflow begin around Douglas Channel and wrap around YVR island and hit us. Then it picks up the proper moisture without having time to moderate . It is the best outcome for SNOW measured in feet vs inches . Otherwise we just end up with a quick hitter and then dry out for a week or so and sublimation melts it all. I prefer the former over the latter. Then if you aren't satisfied ask for a reload to do the dirty deal and crash us to zero farenheit once we have the goods firmly in the ground. Over and out //

 

 

 

The reloads are always a good bet.  You get quick air mass transitions with those and lots of different snow opportunities.

[Gradient Keeper]

Day 6

 

[bainbridgekid]

I remember one day had a definite Fraser River wind at the beginning of the event, and then we had a cold east wind develop here the night of the 2nd snow event. It snowed with temps in the mid 20s. Pretty legit cold.

The cold was absolutely legit. It snowed hard here at 23 degrees at one point with over a foot on the ground.

 

It was extremely impressive but mainly low level outflow based. 850mb temps and thicknesses never got nearly as low as surface temps would have suggested.

[snow_wizard]

Meanwhile the Eastern trough gets eaten up even more on this run.  I was expecting that.

[snow_wizard]

Day 6

 

 

YESSSSS!!!!

[Jesse]

Now we enter the stage where the models flip roles and so do some on the forum.

 

Tomorrow, we will lose the GFS and the EPS will waver, but the UKMET, GEM, ICON, and Euro will get on board.

 

Someone from the Seattle area will go from playing the role of the contrarian to getting on board and someone from the Salem area will go from being enthusiastic about the full monty to bargaining with everyone that cold onshore flow is good enough too.

 

It's going to be a fun few days.

You’ve been here awhile eh?

[runninthruda206]

Looking good so far!

[Slushy Inch]

Euro on board! https://www.tropicaltidbits.com/analysis/models/ecmwf/2020010300/ecmwf_z500a_namer_7.png

[snow_wizard]

We're in!  Day 6 on the ECMWF is unmistakable.  Long live the GFS.

[Weiner Warrior]

I can't wait till Day 2 and it shows cold rain

[VancouverIslandSouth]

Late December 2016 had some of the coldest mid range runs we’ve seen since probably January 2005.

 

Early Jan 2011 has a special place in my heart for busted mid-range cold.

[MossMan]

Would be awesome to see an arctic front blast down Puget Sound with awesome force like 1990 or some of the real old time ones!

[Deweydog]

[snow_wizard]

Now we enter the stage where the models flip roles and so do some on the forum.

 

Tomorrow, we will lose the GFS and the EPS will waver, but the UKMET, GEM, ICON, and Euro will get on board.

 

Someone from the Seattle area will go from playing the role of the contrarian to getting on board and someone from the Salem area will go from being enthusiastic about the full monty to bargaining with everyone that cold onshore flow is good enough too.

 

It's going to be a fun few days.

 

Or maybe a fun few weeks.

[Gradient Keeper]

Day 6 past 4 runs

 

[Deweydog]

Early Jan 2011 has a special place in my heart for busted mid-range cold.

Yeah that was good one too. High risk/high reward kind of battle ground setup. Never looked particularly cold down here.

[Blizzard777]

Or maybe a fun few weeks.

Thats what I’m counting on