December 2020 Weather Observations for the PNW

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Day 3

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Day 4

[Brian_in_Leavenworth]

11 minutes ago, Deweydog said:

It’s interesting they talked about the upper low retrograding under the block, which is something that has always fascinated me about the 1989 blast.  Intense cold air masses with so much overwater trajectory almost always have a tendency to do that as they become cyclogenic.  December 1992 and January 2005 are pretty good examples.

That thing just overwhelmed the norms.  Cold onshore flow with temps in the mid 20’s is pretty incomprehensible.

Also shows how dependent we’ve become on long term leads.  I specifically remember there was no SWS or mention of any potential until Monday morning by NWS Astoria.  Arctic air arrived Wednesday morning.

Here is a gif of that time period.  500 mb pressure, but not the anamolies.

 

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Day 5 Hmmm....

[Deweydog]

4 minutes ago, Brian_in_Leavenworth said:

Here is a gif of that time period.  500 mb pressure, but not the anamolies.

 

A 90dm rise in 500mb heights over Anchorage.

#hohum

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7 minutes ago, Brian_in_Leavenworth said:

Here is a gif of that time period.  500 mb pressure, but not the anamolies.

 

Imagine if the Hudson's Bay vortex phased even more with our cold trough. It could have been even colder.

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Day 6

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NE Canada/Greenland block significantly weaker

[PV=nRT]

5 hours ago, Brian_in_Leavenworth said:

Fascinating.  Didnt know they had AFDs in 1989, considering there was no internet.  I do remember weather summaries over weather radio, but nothing like an AFD with the possibilities and various scenarios and forecasters reasoning for why they are forecasting what they are forecasting.

AFD's have been around since at least the 60s.  They were not meant for public dissemination but to neighboring NWS Offices as a means of giving insight of the thought process for their forecasts.  They were somewhat cryptic.  Brings back some memories.

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Day 7

[Brian_in_Leavenworth]

1 minute ago, PV=nRT said:

AFD's have been around since at least the 60s.  They were not meant for public dissemination but to neighboring NWS Offices as a means of giving insight of the thought process for their forecasts.  They were somewhat cryptic.  Brings back some memories.

That makes sense.  The AFD's now often refer to "in consultation with neighboring offices . . ." or something similar.

[Deweydog]

Looks kinda windstormyish.

[Brian_in_Leavenworth]

7 minutes ago, DJ Droppin said:

NE Canada/Greenland block significantly weaker

From 48 hours ago to tonights run, same hour.

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Day 8

[PV=nRT]

4 hours ago, fubario said:

we called the NGM the 'no good model' back in the day

NGM, Nested Grid Model and before that the LFM, Limited Fine Mesh Model.  Go back even further to the PE, Primitive Equation 6 layer model, the Barotropic, and Baroclinic models.  Can't forget the AVN, Aviation Model , and MRF, Medium Range Models.  Atmospheric modeling has come quite a ways since its infancy.  It will never perfectly model the atmosphere which is obvious in todays models.  They are however much better but still struggle with large scale pattern changes.

[Brian_in_Leavenworth]

4 minutes ago, PV=nRT said:

NGM, Nested Grid Model and before that the LFM, Limited Fine Mesh Model.  Go back even further to the PE, Primitive Equation 6 layer model, the Barotropic, and Baroclinic models.  Can't forget the AVN, Aviation Model , and MRF, Medium Range Models.  Atmospheric modeling has come quite a ways since its infancy.  It will never perfectly model the atmosphere which is obvious in todays models.  They are however much better but still struggle with large scale pattern changes.

Today's models typically go to 10 days, or 16 with the GFS.  Not counting the weeklies or monthlies.  How far out did the old models go to?

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Day 9'er

[SilverFallsAndrew]

Tonight's runs have a real January 2008 vibe.

[PV=nRT]

2 minutes ago, Brian_in_Leavenworth said:

Today's models typically go to 10 days, or 16 with the GFS.  Not counting the weeklies or monthlies.  How far out did the old models go to?

Earliest models I used went out 48 hours.  The PE Model went out 72 hours but the last 24 was a barotropic extension.  The LFM and NGM if I recall were out to 96 hours, don't hold me to that.  The MRF eventually went out to 10 days but was not very reliable the last 5 days.  They all had terrain issues and didn't see the Rockies, Cascades, or the Gorge very well. 

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Day 10

[liquidsnow]

1 minute ago, iFred said:

Winter is still canceled and @liquidsnow is now deputized to tamper down on any fun or excitement.

You dang right son! 

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00z ECMWF 10 Day Rainfall, Snowfall totals

 

[liquidsnow]

39 minutes ago, DJ Droppin said:

Day 10

Thatsa spicy Nina

[snow_wizard]

7 minutes ago, DJ Droppin said:

Day 10

Looks like a block might be thinking about popping up out there,.

[snow_wizard]

Tonight's GFS ensemble was far from terrible.  A sustained period of solidly below normal 850s for the last half of the run.  We may be getting somewhere now.

[snow_wizard]

One has to wonder if the models are beginning to react to the imminent SSW now.  Thank goodness this is soon enough that a good chunk of January will be in play.

[snow_wizard]

Interesting....the wave that gives us the nice cold trough on the GFS at hour 300 is much more pronounced on the ECMWF at day 10 than it is on the GFS at that time.  As it is the GFS takes the thicknesses down to 519 over SEA with that hour 300 trough.  Could this be something?

[snow_wizard]

This GFS run perfectly splits the stratospheric PV in half on this run.  Looking more like the ECMWF now.

[MossMan]

Tonight is the beginning of many great model runs to come...A great January here we come! 

[Deweydog]

[SouthHillFrosty]

[RentonHill]

23 minutes ago, SouthHillFrosty said:

 

[TigerWoodsLibido]

[Deweydog]

 

[Brian_in_Leavenworth]

[GHweatherChris]

Next

[TigerWoodsLibido]

Just now, GHweatherChris said:

Next

[Deweydog]

10 minutes ago, GHweatherChris said:

Next

 

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[Meatyorologist]

06z GFS Init.

I got a good feeling about this one. Using North Pacific view still because NAO/Greenland block is primarily a downstream effect and doesn't hold much bearing over our weather aside from bridging blocks.