December 2015 in the Pacific Northwest

[Gradient Keeper]

This GFS run is definitely making a move towards the Euro. More energy held further west in the Aleutians, resulting in stronger ridge amplification offshore,

Yep, that's what I'm seeing too.

[HighlandExperience]

Yeah i noticed that also. I have had some huge snow events with that pattern. This year reminds me of 2007 winter just warmer. I had 42 inches of snow that year and 54 the next winter. Last three winters here have been terrible.

Hood Canal is going to score something.

[Gradient Keeper]

HR 132 500mb anomalies compared to previous 6z, 00z shows a much more amplified ridge. Comparing to the EURO it's nearly identical.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2015121812/gfs_z500a_namer_23.png

[Gradient Keeper]

HR 144 looks decent. Comparing to the EURO ridge is not quite as strong, slightly less amplified and more progressive, but this run is a step in the EURO direction.

[Gradient Keeper]

Model comparison HR 150 12z
 

http://www.tropicaltidbits.com/analysis/models/gfs/2015121812/gfs_z500a_namer_26.png

 

00z last night

 

http://www.tropicaltidbits.com/analysis/models/gfs/2015121800/gfs_z500a_namer_28.png

[Front Ranger]

HR 144 looks decent. Comparing to the EURO ridge is not quite as strong, slightly less amplified and more progressive, but this run is a step in the EURO direction.

 

Exactly. The changes towards the Euro solution in days 4-6 are what matter.

 

Christmas day would be mostly dry and cold, with a few flurries in spots, if this run were to verify.

[Gradient Keeper]

HR 168 still too progressive and no positive tilt yet into Yukon-BC. That strong 956mb low is overpowering the ridge shoving it southeast. We don't want that.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2015121812/gfs_z500_mslp_namer_29.png

[Gradient Keeper]

Deeper arctic air is not progressing very far south into BC/AB. Not on this run though.

[Gradient Keeper]

Anxious for 12z EURO

[FroYoBro]

Deeper arctic air is not progressing very far south into BC/AB. Not on this run though.

 

You seem to be looking for this every run, yet no models have really shown arctic air getting very far south. I really don't think that really cold arctic air is in the cards for us, but we may get cold enough for frozen precipitation if the low placements are favorable during this time. 

[Gradient Keeper]

You seem to be looking for this every run, yet no models have really shown arctic air getting very far south. I really don't think that really cold arctic air is in the cards for us, but we may get cold enough for frozen precipitation if the low placements are favorable during this time. 

Of course I'm looking at it. Most runs have bitter air moving into Yukon-Alaska-Northwest Territories just after day 4. Some runs have progressed it nearly to the Canadian border, others have not. You're right though, we only need a marginally cold Columbia Basin if we can get a low diving into southwest Oregon.

[Gradient Keeper]

12z GEM kind of looks like the GFS, not quite like the EURO. Tim is the master GEM analyst though, so I'll see what he has to say.

[MR.SNOWMIZER]

Going to be a close one on the posible hood canal event monday or tuesday. It dont take much cold air to dam up over here to make it work out. -3 @ 850 heavy precip and east flow is all it takes.

[Phil]

You seem to be looking for this every run, yet no models have really shown arctic air getting very far south. I really don't think that really cold arctic air is in the cards for us, but we may get cold enough for frozen precipitation if the low placements are favorable during this time.

Yup, at best this is a repeat of the late November event, in terms of amplitude. Raging zonal flow/+AAM over high latitudes thanks to strong PV.

[stuffradio]

The SOI is above 0 now.

[Phil]

The SOI is above 0 now.

There's a CCKW passage ongoing. It'll tumble again eventually, not that it matters much.

[Gradient Keeper]

12z GFS 6-10 day Composite Analog correlation score only 79%, so it does seem the GFS is lost with pattern recognition and things favor the EURO in my opinion.

[Gradient Keeper]

925mb -2 to -3c over PDX with flat gradients Christmas day. Weak low dropping south. Too bad it looks dry unfortunately.

[Timmy]

925mb -2 to -3c over PDX with flat gradients Christmas day. Weak low dropping south. Too bad it looks dry unfortunately.

moisture can find a way in these situations even 24 hours out models show little to none and those lows can spin a little up.

[Gradient Keeper]

moisture can find a way in these situations even 24 hours out models show little to none and those lows can spin a little up.

Christmas Day flurries

[Gradient Keeper]

12z EURO has begun....... here we go......

[BLI snowman]

moisture can find a way in these situations even 24 hours out models show little to none and those lows can spin a little up.

 

The  way this month has gone, I would never bet against moisture. 

[Front Ranger]

Yup, at best this is a repeat of the late November event, in terms of amplitude. Raging zonal flow/+AAM over high latitudes thanks to strong PV.

 

So you think the Euro is out to lunch?

[Front Ranger]

The 12z Canadian goes off the rails after day 5, but up to that point it looks much more like the Euro than the crappy GFS runs.

[Front Ranger]

Going to be a close one on the posible hood canal event monday or tuesday. It dont take much cold air to dam up over here to make it work out. -3 @ 850 heavy precip and east flow is all it takes.

 

12z Euro is looking more favorable for this than the GFS did.

 

It's also much cooler for western WA at day 4 than the GFS.

[Gradient Keeper]

HR 96. Next frame is critical how it handles this 1001mb low

 

http://www.tropicaltidbits.com/analysis/models/ecmwf/2015121812/ecmwf_z500_mslp_wpac_5.png

[Timmy]

Yup, at best this is a repeat of the late November event, in terms of amplitude. Raging zonal flow/+AAM over high latitudes thanks to strong PV.

oh phil... of course we won't be getting an arctic blast by east coast standards.  That is not what we are expecting at all.  We would gladly take a repeat of November at the coldest time of year, should be even better at the surface based on the sun angle.   Are you trying to kill our fun because the east is torching so hard right now?

[Front Ranger]

At day 5, the Euro is still easily stronger/more amplified with the offshore ridge compared to the GFS. Not quite as amplified as the 0z, though. The low in the far west Aleutians is closer, which may cause the ridge to break down sooner.

[Timmy]

hr 120, ridge is more pronounced into the bering sea.

[Gradient Keeper]

HR 120
 

http://www.tropicaltidbits.com/analysis/models/ecmwf/2015121812/ecmwf_z500a_namer_6.png

[Timmy]

At day 5, the Euro is still easily stronger/more amplified with the offshore ridge compared to the GFS. Not quite as amplified as the 0z, though. The low in the far west Aleutians is closer, which may cause the ridge to break down sooner.

Im comparing to yesterdays 12z euro so the times actually match up.  ridge is more amplified at day 5.

[Timmy]

HR 120

 

http://www.tropicaltidbits.com/analysis/models/ecmwf/2015121812/ecmwf_z500a_namer_6.png

http://www.tropicaltidbits.com/analysis/models/ecmwf/2015121712/ecmwf_z500a_namer_7.png

yesterdays euro, 12z

[Gradient Keeper]

PV much further south on this 12z run too

[Front Ranger]

Day 6/Hour 144.

 

 

[Gradient Keeper]

HR 144 Day 6. Ridge sliding east, but maintaining its amplitude whereas the GFS does not

http://www.tropicaltidbits.com/analysis/models/ecmwf/2015121812/ecmwf_z500_mslp_namer_7.png

[Timmy]

HR 144 Day 6. Ridge sliding east, but maintaining its amplitude whereas the GFS does not

 

http://www.tropicaltidbits.com/analysis/models/ecmwf/2015121812/ecmwf_z500_mslp_namer_7.png

more west with cold air, more over water trajectory and cooler as well

[stuffradio]

It's funny how straight of a line the really heavy snow is on the 12Z HRDPS down to OR. Hour 48 is more sporadic for heavier snow from WA into OR.

[Front Ranger]

Hour 168. Christmas.

 

 

[Gradient Keeper]

Day 7 ridge building over southeast US
http://www.tropicaltidbits.com/analysis/models/ecmwf/2015121812/ecmwf_z500a_namer_8.png

[Front Ranger]

The Euro snow maps will be interesting.