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Significant Lowland Snow Threat Beginning Around Feb 20


snow_wizard

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There is strong model agreement that the NW will go into a rather cold and active pattern beginning by the 19th or 20th of the month.  Some GFS ensemble members have suggested 850mb temps dropping below -8 and some below -10.  The latest GFS (12z Feb 9) shows three separate troughs all of which cold enough to bring lowland snow beginning around the 19th and continuing through the remainder of the run.  The ECMWF ensemble mean advertises 850mb temp anomalies around 6C below normal in that time frame.  This is a pattern we have not seen yet this winter and looks very capable of bringing lowland snow.

 

On another note this pattern looks like a dead ringer for a La Nina forced pattern which lines up well with recent AAM and SOI readings.  The El Nino which looked likely for next winter could be in grave danger now.  Oh darn.

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Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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Guest Winterdog

At my location March has outdone February in snowfall by a huge margin since 2000.  It seems like the CZ's are more common and pronounced in March and deliver snow quite often.  I'm looking forward to some big February and March totals this year.

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This is a pattern we have not seen yet this winter and looks very capable of bringing lowland snow.

I disagree and am not buying the idea of significant lowland snowfall. Could be stormy, but that's as far as I would go.

 

We went through this same deal back in January, with the ridging knocked into the WPO domain, with vorticity taking hold over Alaska. That's a death sentence for snow lovers west of the Mississippi River, given the lack of a forcing promoting a -NAO. With the maximum PVA over the NAO domain, there is little to no shot for a wintry outcome in the lowland PNW.

 

The anomalously strong QBO windfield that has biased the wave activity and eddy field to favor a -EPO this winter is now breaking down. So I think the brunt of winter has come and gone over the lower 48.

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I disagree and am not buying the idea of significant lowland snowfall. Could be stormy, but that's as far as I would go.

 

We went through this same deal back in January, with the ridging knocked into the WPO domain, with vorticity taking hold over Alaska. That's a death sentence for snow lovers west of the Mississippi River, given the lack of a forcing promoting a -NAO. With the maximum PVA over the NAO domain, there is little to no shot for a wintry outcome in the lowland PNW.

 

The anomalously strong QBO windfield that has biased the wave activity and eddy field to favor a -EPO this winter is now breaking down. So I think the brunt of winter has come and gone over the lower 48.

 

But I admit I'm looking forward to the start of Spring, so I might be a tad biased. This has been the coldest, driest winter of my life..and I'm ready for it to end. :)

We'll see. We have seen what the models are hinting at a number of times in late winter in recent years. A very cold PV sits over Alaska and occasionally digs down the BC Coast. The normal outcome is a torch for about 80% of the continental United States and somewhat cold in the NW. A pattern like the one being hinted at brought quite a bit of lowland snow in March 2012.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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. On another note this pattern looks like a dead ringer for a La Nina forced pattern which lines up well with recent AAM and SOI readings.  The El Nino which looked likely for next winter could be in grave danger now.  Oh darn.

I think a weak to moderate El Niño is fairly likely for next winter...strength will depend on the rate + amplitude of the swing in the QBO windfield this summer, and solar forcing from March to September. The Walker/Hadley Cells and tropical convection will respond accordingly.

 

However, when looking at things very radically, there's a way to avoid an El Niño and perhaps achieve a La Niña. If I can, I'll start a thread on this and explain how it could be done.

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We'll see. We have seen what the models are hinting at a number of times in late winter in recent years. A very cold PV sits over Alaska and occasionally digs down the BC Coast. The normal outcome is a torch for about 80% of the continental United States and somewhat cold in the NW. A pattern like the one being hinted at brought quite a bit of lowland snow in March 2012.

With the tropospheric PV maximum vertically stacked into the stratosphere over the NAO domain, the Alaskan vorticity is unlikely to dig down the BC coast. Tropical forcing will not favor wave breaking into the NAO domain, so that PV is likely to sit there for awhile. The standing wave over the Atlantic is not going to get the job done, unfortunately.

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I think a weak to moderate El Niño is fairly likely for next winter...strength will depend on the rate + amplitude of the swing in the QBO windfield this summer, and solar forcing from March to September. The Walker/Hadley Cells and tropical convection will respond accordingly.

 

However, when looking at things very radically, there's a way to avoid an El Niño and perhaps achieve a La Niña. If I can, I'll start a thread on this and explain how it could be done.

I was strongly leaning toward a Nino until the recent crazy SOI burst and progressively more negative AAM. The subsurface profile is mildly Nina right now. I'm very surprised how this has evolved. I plan on beginning an ENSO thread also. Usually when we get on a roll for Arctic outbreaks in the NW it takes a Nino winter to break it. That being the case I hope we can delay the Nino for another year.

  • Like 1

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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Guest Winterdog

I disagree and am not buying the idea of significant lowland snowfall. Could be stormy, but that's as far as I would go.

 

We went through this same deal back in January, with the ridging knocked into the WPO domain, with vorticity taking hold over Alaska. That's a death sentence for snow lovers west of the Mississippi River, given the lack of a forcing promoting a -NAO. With the maximum PVA over the NAO domain, there is little to no shot for a wintry outcome in the lowland PNW.

 

The anomalously strong QBO windfield that has biased the wave activity and eddy field to favor a -EPO this winter is now breaking down. So I think the brunt of winter has come and gone over the lower 48.

 

But I admit I'm looking forward to the start of Spring, so I might be a tad biased. This has been the coldest, driest winter of my life..and I'm ready for it to end. :)

I don't think he is saying we are entering a pattern that would yield a classic snow maker here in the PNW but rather a pattern that would be likely to set up situations with cold post frontal convection.  The pattern shown on the models suggests post frontal 850's at -4 to -6 that would produce snow in a convective setup like a convergence zone.  We haven't had that type of setup this winter much.  I believe that most of our late February or March lowland snowfalls are generated from such setups as opposed to the classic pattern that produces a general area wide snowfall.

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I don't think he is saying we are entering a pattern that would yield a classic snow maker here in the PNW but rather a pattern that would be likely to set up situations with cold post frontal convection.  The pattern shown on the models suggests post frontal 850's at -4 to -6 that would produce snow in a convective setup like a convergence zone.  We haven't had that type of setup this winter much.  I believe that most of our late February or March lowland snowfalls are generated from such setups as opposed to the classic pattern that produces a general area wide snowfall.

I had over 3ft of snow in December 2007 with all that cold onshore flow. I want to say the total was 42 and in December 2008 it was 49 or 50. I like that type of pattern.

We come from the land of the ice and snow.

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I had over 3ft of snow in December 2007 with all that cold onshore flow. I want to say the total was 42 and in December 2008 it was 49 or 50. I like that type of pattern.

 

 

Amazing how much snow some places had in December 2007.  I liked 2008 much better as I'm sure most people on here would agree.  I love Arctic air!

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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This is obviously way premature. It could happen and there is historic precedent for it (late February 1936 had a reload of cold air and snow for us), but it's unlikely we see another great pattern this month. Either way, I'd take cold onshore flow or weak Fraser River outflow at this point, since my location hasn't fared particularly well with either of the big blasts this winter.

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This is obviously way premature. It could happen and there is historic precedent for it (late February 1936 had a reload of cold air and snow for us), but it's unlikely we see another great pattern this month. Either way, I'd take cold onshore flow or weak Fraser River outflow at this point, since my location hasn't fared particularly well with either of the big blasts this winter.

Yeah...I pretty much said the pattern will probably be more of a maritime polar snow threat.

  • Like 1

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

Link to comment
Share on other sites

I disagree and am not buying the idea of significant lowland snowfall. Could be stormy, but that's as far as I would go.

 

We went through this same deal back in January, with the ridging knocked into the WPO domain, with vorticity taking hold over Alaska. That's a death sentence for snow lovers west of the Mississippi River, given the lack of a forcing promoting a -NAO. With the maximum PVA over the NAO domain, there is little to no shot for a wintry outcome in the lowland PNW.

 

The anomalously strong QBO windfield that has biased the wave activity and eddy field to favor a -EPO this winter is now breaking down. So I think the brunt of winter has come and gone over the lower 48.

 

But I admit I'm looking forward to the start of Spring, so I might be a tad biased. This has been the coldest, driest winter of my life..and I'm ready for it to end. :)

 

I hope this means the end of the extremely dry weather that Socal has been experiencing this entire season and up until recently, Norcal as well.

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We've seen this pattern before, and I'm really not sure it will do much good for those of us in the lowlands. It seems as though the negative anomalies in Alaska will cause the offshore block to be suppressed more-so than we need, causing more of a zonal flow pattern rather than a cold trough. Hope I'm wrong!

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We've seen this pattern before, and I'm really not sure it will do much good for those of us in the lowlands. It seems as though the negative anomalies in Alaska will cause the offshore block to be suppressed more-so than we need, causing more of a zonal flow pattern rather than a cold trough. Hope I'm wrong!

 

 

The 0z GFS clearly shows lowland snow.  850s below -6, thicknesses dropping to about 519, dead surface pressure gradients (perhaps even slightly northerly at one point), and some moisture being shown during the period where the coldest air is in place.  Given the way the ECMWF and GFS ensembles have looked in that time frame I am saying 50% chance of snow below 500 somewhere in the lowlands between Feb 19 and Feb 22.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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Late February 2009 brought cold onshore flow and -9C 850mb temps to NW Oregon. It snowed about 1.5" in the Salem area on the 26th, that afternoon I went fishing and it was partly sunny and about 45 degrees and you would have never even known that it snowed that morning. 

Snowfall                                  Precip

2022-23: 95.0"                      2022-23: 17.39"

2021-22: 52.6"                    2021-22: 91.46" 

2020-21: 12.0"                    2020-21: 71.59"

2019-20: 23.5"                   2019-20: 58.54"

2018-19: 63.5"                   2018-19: 66.33"

2017-18: 30.3"                   2017-18: 59.83"

2016-17: 49.2"                   2016-17: 97.58"

2015-16: 11.75"                 2015-16: 68.67"

2014-15: 3.5"
2013-14: 11.75"                  2013-14: 62.30
2012-13: 16.75"                 2012-13: 78.45  

2011-12: 98.5"                   2011-12: 92.67"

It's always sunny at Winters Hill! 
Fighting the good fight against weather evil.

 

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how can we tell it has precip versus just cold? this would be hardest to forecast.

A good indicator will be the longitudinal position of the trough as it nears full maturity. In this case it appears it will be pretty favorable. This won't be a dry cold snap. The models continue to indicate it will get cold enough to snow somewhere around the 20th. There is currently some indication there will be another cold snap shortly after the one this thread was created for.

 

In short the cold snap late next week won't be a slam dunk for lowland snow for everyone, but it's likely some places will have some. The latest ECMWF ensemble showed 850s below -5 for at least 60 hours in the hour 204 to hour 276 period, with Seattle bottoming out around -7 or -8. Certainly going to pad our cold monthly average.

Death To Warm Anomalies!

 

Winter 2023-24 stats

 

Total Snowfall = 1.0"

Day with 1" or more snow depth = 1

Total Hail = 0.0

Total Ice = 0.2

Coldest Low = 13

Lows 32 or below = 45

Highs 32 or below = 3

Lows 20 or below = 3

Highs 40 or below = 9

 

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I was also initially thinking this would be a likely period of at least some snow risk to the lowlands, however at least here in Oregon I think it will be a touch too mild for snow to stick below 1000'. Good agreement on the GFS ensembles now for several days with a mean around -5 to -6c and no members below about -8c. 

However LAST time I said this I recall we saw three snowstorms and a marginal arctic blast (-7.3c was the coldest H8 temp over Salem), so with that in mind I hope we trend colder. I am not too excited about it yet.

The Pacific Northwest: Where storms go to die.

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I disagree and am not buying the idea of significant lowland snowfall. Could be stormy, but that's as far as I would go.

 

We went through this same deal back in January, with the ridging knocked into the WPO domain, with vorticity taking hold over Alaska. That's a death sentence for snow lovers west of the Mississippi River, given the lack of a forcing promoting a -NAO. With the maximum PVA over the NAO domain, there is little to no shot for a wintry outcome in the lowland PNW.

 

The anomalously strong QBO windfield that has biased the wave activity and eddy field to favor a -EPO this winter is now breaking down. So I think the brunt of winter has come and gone over the lower 48.

 

Standing by this. Here-in lies the danger of starting threads based on the clown-range GFS.

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I'm not sure that it's the best idea to be dedicating entire threads to tracking a storm that showed up on one model run. It gives the clean up crew on this forum more work than necessary.

 

Also, it's the GFS....

Euro was atrocious this winter... GEM was the most accurate when it came to forecasting lowland snow.

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Would you like me to institute a thread preview where we can make sure only the threads pertaining to immediate weather models, predictions, and observations are posted? I can also make sure that they fall within the realm of "realistic and pragmatic discussion", and that we keep peoples emotions tempered.

 

I'm kidding of course, and you should lighten up a little.

 

This actually sounded great until I read your last line.  :lol:

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A good indicator will be the longitudinal position of the trough as it nears full maturity. In this case it appears it will be pretty favorable. This won't be a dry cold snap. The models continue to indicate it will get cold enough to snow somewhere around the 20th. There is currently some indication there will be another cold snap shortly after the one this thread was created for.

 

In short the cold snap late next week won't be a slam dunk for lowland snow for everyone, but it's likely some places will have some. The latest ECMWF ensemble showed 850s below -5 for at least 60 hours in the hour 204 to hour 276 period, with Seattle bottoming out around -7 or -8. Certainly going to pad our cold monthly average.

 

So perhaps it seems likely that there is a chance of snow like you expected. Now the question is: is this what you thought so far was going to happen?

 

Looks like our best shot of sticking snow is Sat night into Sun?

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