PNW December 2022 - Part II

[Brian_in_Leavenworth]

1 minute ago, Front Ranger said:

He's a pro met and a 174 hour snow map from the GFS is breaking his heart? 

Euro was also a big letdown for them.

[bainbridgekid]

3 minutes ago, TT-SEA said:

I think the surface of the ground responds very quickly to changes in temperature/dewpoint.     If its snowing and not sticking then the weather conditions are to blame... not the ground.   And vice versa.

This is definitely true. The very top surface layer of ground responds very quickly to the air. Same reason frost forms quickly in the evening once the temp reaches freezing even after a 50 degree sunny day. Pavement is a bit different and takes longer to cool off (urban heat island) but once it’s actually below freezing it almost always sticks there quickly too.

[snow_wizard]

2 minutes ago, Front Ranger said:

He's a pro met and a 174 hour snow map from the GFS is breaking his heart? 

Take the GFS with a giant grain of salt these days.  I will say the longer the cold hangs out in BC and the NW the more problematic things may get for them.

[Brian_in_Leavenworth]

3 minutes ago, LowerGarfield said:

Can someone copypaste Spokane's AFD? I'm on my phone at work so I can't do it but I want to know what you think.

Sorry for the blue highlights, I don't know how to change that.

DISCUSSION...
Tonight through Sunday Night: Weather changes are in store as a
blocking upper ridges amplifies off the coast allowing a cold
upper trough to carve out over western Canada. Not much change in
the weather through Saturday morning with continued stratus and
areas of freezing fog. The stratus will again limit temperature
drops tonight with lows mainly in the teens to low 20s. Saturday
afternoon into Saturday night as the upper trough drops south with
an advancing arctic front, broad isentropic ascent develops below
700mb as winds back to the southwest. Several models are
generating light snow across Eastern WA, northern mountains, and
the ID Panhandle and thus have gone above NBM POP's especially
Saturday night into Sunday. Yet with the air mass is dry above 
700mb, and thus the shallow nature of the precipitation should 
yield light snow amounts. The exception is along the Cascade crest
and Central Panhandle Mountains where upslope flow will enhance
snow totals. A mid level wave passing through Sunday afternoon
into Sunday night along with an arctic front beginning to make
inroads into the area will likely give another boost to the snow.
For now have issued a Winter Weather Advisory for the Central
Panhandle Mountains where confidence is highest of moderate snow
amounts of 4-7". For the remainder of the ID Panhandle, Palouse,
and Spokane area 1-2" is possible by Monday morning with local 
amounts of 2-4" under heavier snow bands not out of the question.
Another area of higher snow amounts will be along the Cascade
crest with 5-10" possible. But with the westerly flow amounts away
from the crest should be much lighter in the 1-3" range. JW

Monday through Friday: A weakening ridge along the coast will give 
way to a series of quick moving troughs through the period. With a 
decent moisture plume, widespread snow showers are expected across 
the Inland Northwest. Temperatures will continue to be cold with 
overnight lows in the low teens and single digits.

The wave from Sunday will continue to exit the region on Monday. 
It will primarily impact Southeast WA and lower ID Panhandle as it
exits the region. It is indicating good chance of 1 inch of snow 
for most of the low lying areas. The higher terrain can expect 
amounts near 3 inches through Monday. 

The next wave will be late Tuesday and Wednesday morning. Confidence 
of snow amount with this wave a decreased as models have pulled back 
on the moisture support. It continues to have decent west to east 
zonal flow. The Central Basin has less than a 20% percent chance of 
an inch. The Cascades and ID Panhandle mountains have a greater than 
30% chance of 6 inches or more through Wednesday morning. Wednesday 
morning is expected to be coldest morning with widespread single 
digit temperatures across the Basin.

The wave on Thursday and Friday will bring warmer temperatures and 
more moisture with it. It is the warmer temperatures that is 
limiting the confidence of potential widespread snow for the low 
lying areas. While it will start as snow, it is expected to 
transition through the day to a wintry mix and freezing precip 
across the Basin. It will be another round of snow for the 
mountains though but potential amounts are not expected to be 
significant. 

[LowerGarfield]

2 minutes ago, snow_wizard said:

Are you talking about snow or cold they aren't in for?  The snow could be more complicated I suppose.

Snow.

[Cold Snap]

7 minutes ago, TT-SEA said:

10-day snowfall total.    So silly.  

Cliff Mass is gonna use that on his blog and say rain/snow mix with 500 foot snow levels next week.

[snow_wizard]

1 minute ago, Front Ranger said:

Yes, but ones associated with Arctic fronts are different because the front itself is sinking south, causing convergence with warmer air as it does.

Not usually as powerful as the CZs that develop north of Seattle, though.

Indeed.  An Arctic front could also be called an atypical convergence zone.  An Arctic front is a C-Zone by its very nature due to higher pressure both north and south of the front itself.

[LowerGarfield]

1 minute ago, Brian_in_Leavenworth said:

Sorry for the blue highlights, I don't know how to change that.

DISCUSSION...
Tonight through Sunday Night: Weather changes are in store as a
blocking upper ridges amplifies off the coast allowing a cold
upper trough to carve out over western Canada. Not much change in
the weather through Saturday morning with continued stratus and
areas of freezing fog. The stratus will again limit temperature
drops tonight with lows mainly in the teens to low 20s. Saturday
afternoon into Saturday night as the upper trough drops south with
an advancing arctic front, broad isentropic ascent develops below
700mb as winds back to the southwest. Several models are
generating light snow across Eastern WA, northern mountains, and
the ID Panhandle and thus have gone above NBM POP's especially
Saturday night into Sunday. Yet with the air mass is dry above 
700mb, and thus the shallow nature of the precipitation should 
yield light snow amounts. The exception is along the Cascade crest
and Central Panhandle Mountains where upslope flow will enhance
snow totals. A mid level wave passing through Sunday afternoon
into Sunday night along with an arctic front beginning to make
inroads into the area will likely give another boost to the snow.
For now have issued a Winter Weather Advisory for the Central
Panhandle Mountains where confidence is highest of moderate snow
amounts of 4-7". For the remainder of the ID Panhandle, Palouse,
and Spokane area 1-2" is possible by Monday morning with local 
amounts of 2-4" under heavier snow bands not out of the question.
Another area of higher snow amounts will be along the Cascade
crest with 5-10" possible. But with the westerly flow amounts away
from the crest should be much lighter in the 1-3" range. JW

Monday through Friday: A weakening ridge along the coast will give 
way to a series of quick moving troughs through the period. With a 
decent moisture plume, widespread snow showers are expected across 
the Inland Northwest. Temperatures will continue to be cold with 
overnight lows in the low teens and single digits.

The wave from Sunday will continue to exit the region on Monday. 
It will primarily impact Southeast WA and lower ID Panhandle as it
exits the region. It is indicating good chance of 1 inch of snow 
for most of the low lying areas. The higher terrain can expect 
amounts near 3 inches through Monday. 

The next wave will be late Tuesday and Wednesday morning. Confidence 
of snow amount with this wave a decreased as models have pulled back 
on the moisture support. It continues to have decent west to east 
zonal flow. The Central Basin has less than a 20% percent chance of 
an inch. The Cascades and ID Panhandle mountains have a greater than 
30% chance of 6 inches or more through Wednesday morning. Wednesday 
morning is expected to be coldest morning with widespread single 
digit temperatures across the Basin.

The wave on Thursday and Friday will bring warmer temperatures and 
more moisture with it. It is the warmer temperatures that is 
limiting the confidence of potential widespread snow for the low 
lying areas. While it will start as snow, it is expected to 
transition through the day to a wintry mix and freezing precip 
across the Basin. It will be another round of snow for the 
mountains though but potential amounts are not expected to be 
significant. 

Thank you, Brian in Bavaria. Seriously that's wonderful.

[Brennan]

I still can't fathom the idea that the GFS is completely missing on this feature. This system has potential to be a huge snow maker for places north of the low. As it stands it stays hung up north of the border as it passes east.  

Edited December 16, 2022 by Brennan

[Requiem]

3 minutes ago, Brian_in_Leavenworth said:

Euro was also a big letdown for them.

CMC and UKMET as well 

[snow_wizard]

1 minute ago, Cold Snap said:

Cliff Mass is gonna use that on his blog and say rain/snow mix with 500 foot snow levels next week.

The sad thing is it's the fault of the GFS operational.  Garbage in = garbage out.  They royally f...ed up the GFS on the last two upgrades.

[TigerWoodsLibido]

1 minute ago, snow_wizard said:

The sad thing is it's the fault of the GFS operational.  Garbage in = garbage out.  They royally f...ed up the GFS on the last two upgrades.

Looks like it's gonna nail the snow forecast for here so it's got that in its favor.

[snow_wizard]

1 minute ago, Brennan said:

I still can't fathom the idea that the GFS is completely missing on this feature. If the GFS does cave, does it send this further south, or do away with it completely? This system has potential to be a huge snow maker for places north of the low. As it stands it stays hung up north of the border as it passes east.  

The further south the cold goes the further south the snowiest zone will sink.  You will have multiple snow chances though.

[xfkirsten]

My hockey game on Sunday night is in Everett - this could be an interesting commute...

(The league has gotten so desperate to find available ice that they're renting out 8,000-seat Angel of the Winds Arena for our D-level beer league team )

[snow_wizard]

I'm going to have 30 freezing min temps in the bag at midnight tonight.  Really good for this early.

40/25 here today.

[MR.SNOWMIZER]

14 minutes ago, Brian_in_Leavenworth said:

 

Hahaha Take that turds!

[TacomaWx]

Just now, snow_wizard said:

I'm going to have 30 freezing min temps in the bag at midnight tonight.  Really good for this early.

40/25 here today.

41/29 here. -2.5 degrees this month already with a cold wave on the way. 

[Terreboner]

This is unbelievable.  Look at these temperature spreads and probabilities.  Everything, and I mean everything, is up in the air.

From Pendleton AFD:

Also, beginning late Tuesday into Wednesday, while precipitation
type remains mainly snow in the mountains, the lower elevations
become far more uncertain. There is more of a chance of liquid
precipitation rather than freezing or frozen, due to increasingly
warmer temperatures during the latter part of next week. However,
this said, the latest ensembles still show that there is a very
significant amount of variance in the temperature forecasts. This
is especially the case for Thursday, with a high temperature
range of 4 to 54 degrees F from the 10th to the 90th percentile.
The range is 13 to 47 degrees F from the 25th to the 75th
percentile, which is still a very large spread. Therefore,
confidence in precipitation type and temperatures for the latter
part of next week is very low (about 10-20 percent). The longer
range models are still having a great difficulty in ironing out
the temperature, and therefore the precipitation type forecast in
the extended range forecast.

[Cloud]

5 minutes ago, snow_wizard said:

The sad thing is it's the fault of the GFS operational.  Garbage in = garbage out.  They royally f...ed up the GFS on the last two upgrades.

I'm trying to look back into it but I think there was a twitter tweet from this week about some discussions with the GFS regarding its snow and temperature outputs. That to me raises an alarm that the model is currently broken. 

[bishbish777]

So if the GFS completely caves, can we just stop using it in the future...?

[snow_wizard]

3 minutes ago, TacomaWx said:

41/29 here. -2.5 degrees this month already with a cold wave on the way. 

I'm running -3.7 month to date.  SEA is about -4.5.

[snow_wizard]

4 minutes ago, Terreboner said:

This is unbelievable.  Look at these temperature spreads and probabilities.  Everything, and I mean everything, is up in the air.

From Pendleton AFD:

Also, beginning late Tuesday into Wednesday, while precipitation
type remains mainly snow in the mountains, the lower elevations
become far more uncertain. There is more of a chance of liquid
precipitation rather than freezing or frozen, due to increasingly
warmer temperatures during the latter part of next week. However,
this said, the latest ensembles still show that there is a very
significant amount of variance in the temperature forecasts. This
is especially the case for Thursday, with a high temperature
range of 4 to 54 degrees F from the 10th to the 90th percentile.
The range is 13 to 47 degrees F from the 25th to the 75th
percentile, which is still a very large spread. Therefore,
confidence in precipitation type and temperatures for the latter
part of next week is very low (about 10-20 percent). The longer
range models are still having a great difficulty in ironing out
the temperature, and therefore the precipitation type forecast in
the extended range forecast.

It's understandable with the mother lode of cold air available in Southern BC at the time in question.

[LowerGarfield]

3 minutes ago, Terreboner said:

This is unbelievable.  Look at these temperature spreads and probabilities.  Everything, and I mean everything, is up in the air.

From Pendleton AFD:

Also, beginning late Tuesday into Wednesday, while precipitation
type remains mainly snow in the mountains, the lower elevations
become far more uncertain. There is more of a chance of liquid
precipitation rather than freezing or frozen, due to increasingly
warmer temperatures during the latter part of next week. However,
this said, the latest ensembles still show that there is a very
significant amount of variance in the temperature forecasts. This
is especially the case for Thursday, with a high temperature
range of 4 to 54 degrees F from the 10th to the 90th percentile.
The range is 13 to 47 degrees F from the 25th to the 75th
percentile, which is still a very large spread. Therefore,
confidence in precipitation type and temperatures for the latter
part of next week is very low (about 10-20 percent). The longer
range models are still having a great difficulty in ironing out
the temperature, and therefore the precipitation type forecast in
the extended range forecast.

Ty for posting Pendleton's. Same deal here on the East side.

[snow_wizard]

3 minutes ago, bishbish777 said:

So if the GFS completely caves, can we just stop using it in the future...?

I would really like to, but I can't help myself.

[Jbolin]

12 minutes ago, Cold Snap said:

Cliff Mass is gonna use that on his blog and say rain/snow mix with 500 foot snow levels next week.

 

[Prairiedog]

6 minutes ago, Brennan said:

I still can't fathom the idea that the GFS is completely missing on this feature. If the GFS does cave, does it send this further south, or do away with it completely? This system has potential to be a huge snow maker for places north of the low. As it stands it stays hung up north of the border as it passes east.  

Just going from several similar situations in the past number of years, the GFS was the most accurate.  I'm just suggesting there's a higher probability it will be right again.  There are probabilities on the table for both the EURO and GFS being right but just going on past similar events and with opposing model solutions, I think the GFS won't cave.  It just seems to do better with this type of scenario.  All I got to go on.  I'm rooting for the EURO.  I'm just not betting on it.  I really do hope I'm wrong. 

[Perturbed Member]

6 minutes ago, Brennan said:

I still can't fathom the idea that the GFS is completely missing on this feature. If the GFS does cave, does it send this further south, or do away with it completely? This system has potential to be a huge snow maker for places north of the low. As it stands it stays hung up north of the border as it passes east.  

 

The other models used to have that low and have now more or less done away with even developing it. It was good for BC snow but otherwise it was terrible for all of OR and most of western WA as it quickly wiped out the cold. 

Most models don't develop that low now and the southern energy dominates and things look much more suppressed. Much better for more prolonged cold. 

[snow_wizard]

4 minutes ago, Cloud said:

I'm trying to look back into it but I think there was a twitter tweet from this week about some discussions with the GFS regarding its snow and temperature outputs. That to me raises an alarm that the model is currently broken. 

It's even terrible on the 500mb stuff now.

[TT-SEA]

5 minutes ago, bishbish777 said:

So if the GFS completely caves, can we just stop using it in the future...?

It will always be very popular when its showing 40 inches of snow in Seattle.

[snow_wizard]

1 minute ago, Prairiedog said:

Just going from several similar situations in the past number of years, the GFS was the most accurate.  I'm just suggesting there's a higher probability it will be right again.  There are probabilities on the table for both the EURO and GFS being right but just going on past similar events and with opposing model solutions, I think the GFS won't cave.  It just seems to do better with this type of scenario.  All I got to go on.  I'm rooting for the EURO.  I'm just not betting on it.  I really do hope I'm wrong. 

Everything is against the GFS right now.  It didn't used to be like this.

[Brennan]

1 minute ago, Prairiedog said:

Just going from several similar situations in the past number of years, the GFS was the most accurate.  I'm just suggesting there's a higher probability it will be right again.  There are probabilities on the table for both the EURO and GFS being right but just going on past similar events and with opposing model solutions, I think the GFS won't cave.  It just seems to do better with this type of scenario.  All I got to go on.  I'm rooting for the EURO.  I'm just not betting on it.  I really do hope I'm wrong. 

I seem to remember something like this happening in recent years, where we were all shocked at how well the GFS did in comparison to the EURO and others... Can't remember when, but within the last 5 years. I tend to think the GFS will be right as well... Hoping for a blend between the EURO and GFS. 

[snow_wizard]

Just now, TT-SEA said:

It will always be very popular when its showing 40 inches of snow in Seattle.

We knew that was garbage too though.

[snow_wizard]

Just now, Brennan said:

I seem to remember something like this happening in recent years, where we were all shocked at how well the GFS did in comparison to the EURO and others... Can't remember when, but within the last 5 years. I tend to think the GFS will be right as well... Hoping for a blend between the EURO and GFS. 

As I've said...I have yet to have that sinking feeling with this event.  This looks poised to work out, but we'll see.

[Meatyorologist]

7 minutes ago, Prairiedog said:

Just going from several similar situations in the past number of years, the GFS was the most accurate.  I'm just suggesting there's a higher probability it will be right again.  There are probabilities on the table for both the EURO and GFS being right but just going on past similar events and with opposing model solutions, I think the GFS won't cave.  It just seems to do better with this type of scenario.  All I got to go on.  I'm rooting for the EURO.  I'm just not betting on it.  I really do hope I'm wrong. 

I share a similar sentiment, but this is a new GFS we are talking about. One that admittedly hasn't performed so well for our area.

[Terreboner]

3 minutes ago, snow_wizard said:

As I've said...I have yet to have that sinking feeling with this event.  This looks poised to work out, but we'll see.

Hard to be skeptical when almost every model has shown improvements within 72 hours.

[Cloud]

I'm gonna leave this one here.... found it from last year, but I highly doubt a year's worth of time is enough for the GFS to close the gap on a  consistently better ECMWF. As the GFS gets "better" -- so does the Euro. 

Not saying the GFS is always wrong, there are some aspects where it's very strong, but in terms of skillset in predicting our weather, the Euro is still WAY better. 

[snow_wizard]

3 minutes ago, Meatyorologist said:

I share a similar sentiment, but this is a new GFS we are talking about. One that admittedly hasn't performed so well for our area.

No doubt it used to have some success.

[TacomaWx]

It’s coming. 

[Deweydog]

Forecast contest!

[Perturbed Member]

Really pleased to see this feature continue to show up. The arctic front reaches NW OR and then you get some kind of deformation over the same area as the low approaches. 18z ICON and RGEM continue to have it. 

 

It was there on the 12z GEM and Euro too but the euro had the low a good bit further north. 

 

 

I think the GFS is entirely on its own and it will completely cave tonight and start to look more like these models. Cold air penetrates further south, limited to no cyclogenesis up north by BC. There will still be uncertainty over where that low goes on Tuesday. The ICON and GEM have a better track for NW OR but the Euro takes it further north and gives snow to western WA and snow to ZR for PDX. 

I'm sure we will see lots of waffling around on the models on exactly how this low tracks.