December Weather In the PNW

[DareDuck]

It was 12 in Bend when I left for work this morning. Up at 6300’ it’s 35. Going to be a warm one today above the inversion.

[Deweydog]

Santa will be making a westerly approach at PDX according to the 12z.

[TT-SEA]

Santa will be making a westerly approach at PDX according to the 12z.

 

Yep... cold east winds and sunshine.   

[Kayla]

Santa will be making a westerly approach at PDX according to the 12z.

 

Good old 10L is my favorite!

[Brian_in_Leavenworth]

12Z followed the trend of the ensembles and parked the big ridge right over us around Christmas     

[Deweydog]

Good old 10L is my favorite!

Should be a good view of the St. Johns Bridge and Sauvie Island.

[Phil]

[Phil]

Sounds of the wind here this morning before the sun comes up...

 

https://vimeo.com/246594215

I love that sound. That dull roar through the trees basically defines winter for me.

[snow_wizard]

Pretty good 12z run.  A legit cold shot and then a ridge moves in right over us again.  At the end of the run another ridge apporoaches from the WNW which promises another round of retrogression.  Many freezing low temps the remainder of the month if this verifies.  FWIW the CFS is showing cold on every run now.  In fact out of the last 4 all showed multiple cold shots over the next 45 days.

[Brian_in_Leavenworth]

Pretty good 12z run.  A legit cold shot and then a ridge moves in right over us again.  At the end of the run another ridge apporoaches from the WNW which promises another round of retrogression.  Many freezing low temps the remainder of the month if this verifies.  FWIW the CFS is showing cold on every run now.  In fact out of the last 4 all showed multiple cold shots over the next 45 days.

Again those are the ensembles?  The "operational" or control run or whatever that is  has been showing warm for most of the last week or runs.

[Deweydog]

Again those are the ensembles? The "operational" or control run or whatever that is has been showing warm for most of the last week or runs.

The CFS has a popular "create your own model run" function.

[Jesse]

[TT-SEA]

I love that sound. That dull roar through the trees basically defines winter for me.

 

Cable news channels show a very snowy DC this morning. 

[Jesse]

12z ensembles are actually super decent.

[TT-SEA]

Fog is hanging tough around the Sound...

 

[Farmboy]

Very foggy and 22 here right now.

[snow_wizard]

Again those are the ensembles?  The "operational" or control run or whatever that is  has been showing warm for most of the last week or runs.

 

I'm a bit confused about all of that.  The way they present it on the Weatherbell site doesn't make it totally clear.

[snow_wizard]

12z ensembles are actually super decent.

 

Many members get into the -7 to -8 range.  One thing people need to keep in mind is if we get a shot of legit cold (especially if it's with snow) going into a ridge again is not a bad thing as long as it doesn't last too long.

[Brian_in_Leavenworth]

I'm a bit confused about all of that.  The way they present it on the Weatherbell site doesn't make it totally clear.

At the wx.graphics site, they have the CFS monthlies, and from there, you can go to the "last 25 stamps" and see the trend.  But I don't think it is emsembles, probably the operational.

[snow_wizard]

The easterly gradients are stronger this morning than what had been advertised on previous model runs so today may be a bit warmer than yesterday in some places.  On the other hand the angle of the gradient might mitigate that.  Tomorrow's gradient looks more like yesterday (if that actually verifies).

[snow_wizard]

At the wx.graphics site, they have the CFS monthlies, and from there, you can go to the "last 25 stamps" and see the trend.  But I don't think it is emsembles, probably the operational.

 

On Weatherbell even the monthly composite is looking decent for January.  Besides that I am confident about January anyway.

[TT-SEA]

The easterly gradients are stronger this morning than what had been advertised on previous model runs so today may be a bit warmer than yesterday in some places.  On the other hand the angle of the gradient might mitigate that.  Tomorrow's gradient looks more like yesterday (if that actually verifies).

 

The easterly gradient was shown to be stronger today on every single run this week of the WRF and ECMWF.

 

The gradient angle will mitigate that for the South Sound for sure as I mentioned last night.  

 

That being said... SEA is back down to 1/8th mile visibility in fog so clearly the easterly gradients have slacked off there.

[Deweydog]

The easterly gradient was shown to be stronger today on every single run this week of the WRF and ECMWF.

 

The gradient angle will mitigate that for the South Sound for sure as I mentioned last night.

Tim for president!

[TT-SEA]

Up to 44 here now with a brisk wind continuing.   

 

My son is skiing at Alpental and said its absolutely freezing at the bottom in the clouds and very warm at the top in the sunshine.  

[Farmboy]

Many members get into the -7 to -8 range.  One thing people need to keep in mind is if we get a shot of legit cold (especially if it's with snow) going into a ridge again is not a bad thing as long as it doesn't last too long.

We should make it clear to this ridge in no uncertain terms that it's presence here is not entirely appreciated... Hopefully it will take the hint and head west...

[MossMan]

Only up to 31 so far...about the same as yesterday at this time. Wall to wall sunshine!

[Brian_in_Leavenworth]

I did find an interesting web site for CFS ensembles, and I looked up the guys name who runs it, and he is a "Science & Operations Officer at NOAA/National Weather Service", so it is a legit site, even though it is not a .gov site.  http://cfs.hopwrf.info/  Good tools there, lots of maps.  It says " The output on this site is based on a 20-member ensemble generated from the four daily CFS control runs (00, 06, 12, & 18 UTC) over the past five days. Output is updated as each cycle is processed, and is typically available approximately 15 hours after cycle time (e.g. output which includes the latest 00 UTC run is available around 15 UTC)."

 

 

[stuffradio]

Almost a 50% chance of a below normal period for Christmas eve.

 

[TT-SEA]

The easterly gradients are stronger this morning than what had been advertised on previous model runs so today may be a bit warmer than yesterday in some places.  On the other hand the angle of the gradient might mitigate that.  Tomorrow's gradient looks more like yesterday (if that actually verifies).

 

 

Tomorrow the ECMWF shows more of a northerly gradient around Seattle.   That provides more mixing for the South Sound compared to today.

 

[TigerWoodsLibido]

Almost a 50% chance of a below normal period for Christmas eve.

 

2017120900_054@007_E1_north@america_I_NAEFS@TEMPERATURE_anomaly@probability@below@normal@week2_198.png

 

Puget Sound and Willamette Valley well below normal.

[Kayla]

Should be a good view of the St. Johns Bridge and Sauvie Island.

 

One of the most beautiful approaches in the lower 48 IMO.

[TT-SEA]

One of the most beautiful approaches in the lower 48 IMO.

Landing in Seattle is prettier.

[snow_wizard]

I did find an interesting web site for CFS ensembles, and I looked up the guys name who runs it, and he is a "Science & Operations Officer at NOAA/National Weather Service", so it is a legit site, even though it is not a .gov site.  http://cfs.hopwrf.info/  Good tools there, lots of maps.  It says " The output on this site is based on a 20-member ensemble generated from the four daily CFS control runs (00, 06, 12, & 18 UTC) over the past five days. Output is updated as each cycle is processed, and is typically available approximately 15 hours after cycle time (e.g. output which includes the latest 00 UTC run is available around 15 UTC)."

 

 

 

Good!  That clears up the mystery of the ensemble vs operational question.

[Kayla]

Landing in Seattle is prettier.

 

Seattle is beautiful as well, but runway 10 at PDX is stunning over St. Johns along the Columbia looking dead on at Mt. Hood.

[Brian_in_Leavenworth]

Good!  That clears up the mystery of the ensemble vs operational question.

Yeah, I thought that they ran CFS ensembles like they did the GFS and Euro ensembles.  I found this at the NOAA site:

 

"How many CFS forecasts should be combined into an ensemble?

Because climate runs are done daily from different sets of initial conditions, we can combine the different runs to give an ensemble of climate forecasts.  Multiple climate runs allow climate forecasters to obtain probabilities for seasonal precipitation and temperature anomalies.  Given the uncertainty in climate forecasts, this is a natural application of the ensemble method.  The CPC uses around 40 CFS forecasts to obtain reasonable climate forecast probabilities and a good ensemble mean climate forecast."

 

Tropical Tidbits does their weekly based on 48 forecasts, or 12 days.  That other web site does it over 5 days, or 20 runs.  CPS says 40 runs or 10 days, but I wonder if that is for the monthlies, not the weeklies.    And I think the above statement was written several years ago, before version 2, and maybe before they even did the weeklies.  Anyway, regardless of number, now we know how they do their ensembles.

[MossMan]

Seattle is beautiful as well, but runway 10 at PDX is stunning over St. Johns along the Columbia looking dead on at Mt. Hood.

San Francisco during landing is also quite stunning on a clear day!

[snow_wizard]

Almost a 50% chance of a below normal period for Christmas eve.

 

2017120900_054@007_E1_north@america_I_NAEFS@TEMPERATURE_anomaly@probability@below@normal@week2_198.png

 

This is actually better than it sounds.  These are broken into three groups.  Below, near normal, and above.  If you have a 50% chance of below that means you only have a 25% chance of above.

[Jesse]

San Francisco during landing is also quite stunning on a clear day!

I’ve heard landing a floatplane on Lake Goodwin and spooking the jetskiiers there is quite satisfying as well.

[MossMan]

I’ve heard landing a floatplane on Lake Goodwin and spooking the jetskiiers there is quite satisfying as well.

Nah the jetskiiers love to race the float planes that are landing and taking off!

[MR.SNOWMIZER]

I kinda like Lax, nothing like smog and upside down stripped cars decorating the streets below.