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February Weather in the Pacific Northwest

Deweydog

By Deweydog
in West of the Rockies

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jaya
jaya

Most cold air west of the Cascades comes in from aloft (with exception to the small region around the gaps in the terrain.  Air aloft is cold with this system.  It looks cold.    For snow, I want to s

jaya
jaya

I'm not sure I like the details in any of the models. Almost anything can happen.   I think big picture instead of mesoscale - and worry about the mesoscale a few hours out.   Let's keep an eye on the

jaya
jaya

Snowing in South Everett.

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TT-SEA Grand Master

TT-SEA

Posted
Posted

I’ve have mentioned this before several days ago about the location that Seattle is in between two mountain ranges makes it difficult for it to snow which is due to shadowing from either side. There will be shadowing from the Olympics today and there is no amount of you needing to have the last word (or your lack of knowledge) changing that ). I stand by everything that I have said.

The precip shield arrives later this evening. The Olympics will not be a problem for Seattle at any point with this event.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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TT-SEA Grand Master

TT-SEA

Posted
Posted

12Z ECMWF also shows light snow for Friday across the region. Olympic shadowing might be more an issue with that system as its an open trough and not a defined low.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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Front Ranger Grand Master

Front Ranger

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The projected radar loop on the HRRR model is usually too aggressive in a offshore flow situations. I have seen many times when it shows precip over us but it is not actually reaching the ground. I have come to expect it.

 

Its not even doing that for tonight...

 

1ref_t1sfc_f17.png

HRRR is terrible that far out.

A forum for the end of the world.

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TT-SEA Grand Master

TT-SEA

Posted
Posted

12z Euro shows a hair more snow for the Central Sound during the day Friday than the 00z. Still a noticeable shadow.

Now that is an Olympic Mountains

shadow. :)

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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wxmet Enthusiast

wxmet

Posted
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It will not be a shadowing problem... it will be an offshore flow problem for the Seattle area.

 

 

So according to you there will not be shadowing, but there is an offshore flow problem, but there is a shadowing problem but it's from the Cascades. How do you maintain this state of cognitive dissonance?

 

According to you the NAM maps are insufficient due to their lack of detail but yet the NAM runs on a higher horizontal resolution than the ECMWF. 

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Geos Proficient

Geos

Posted
Posted

Just took a look at the 12z GFS.. you weren't kidding, looks a lot better than previous runs.

 

Nice snowy night on Friday evening/night leaves us with 2-4 inches by 10AM Saturday and another shot on Sunday night that drops another 1-3 inches.

 

Map below is for 10AM Monday.

 

Holy cow. This is a surprise!

 

Got down to 20* here this morning. Coldest low of the season. Funny how it came in late February.

 

Will be interesting to see if it can snow enough today to get the ground white. 

Mercer Island, 350 ft

2021-2022: 11.6", 02/21

2020-2021: 15.6"

2019-2020: ~10"

2018-2019 winter snowfall total: 29.5"

2017-2018: 9.0", 2016-2017: 14.0"

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TT-SEA Grand Master

TT-SEA

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Posted

So according to you there will not be shadowing, but there is an offshore flow problem, but there is a shadowing problem but it's from the Cascades. How do you maintain this state of cognitive dissonance?

 

According to you the NAM maps are insufficient due to their lack of detail but yet the NAM runs on a higher horizontal resolution than the ECMWF. 

 

WTF are you talking about?   You showed onshore flow and said that Seattle might be shadowed.   If you were talking about the Cascades then you would have showed a map with offshore flow... which is what will be happening when the precip is occurring.    But there might be enough precip to overcome even that.  

 

You are just switching the story now and saying the Cascades might do the shadowing.    That is not what you were thinking originally.  :)

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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TT-SEA Grand Master

TT-SEA

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It's just terrible in general more than a few hours out.

 

Actually I have used it many times to gauge when precip will start or end even 18+ hours out and its usually pretty accurate.   It can be a very good tool.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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wxmet Enthusiast

wxmet

Posted
Posted

WTF are you talking about?   You showed onshore flow and said that Seattle might be shadowed.   If you were talking about the Cascades then you would have showed a map with offshore flow... which is what will be happening when the precip is occurring.    But there might be enough precip to overcome even that.  

 

You are just switching the story now and saying the Cascades might do the shadowing.    That is not what you were thinking originally.  :)

 

Thanks for proving my point  ;)

 

When I first posted today, I did not mention anything about which mountain range would be causing shadowing until you responded to me. In you response, your stated "It will not be a shadowing problem" but now you are saying it will be caused by the Cascades. It seems you are switching your story. How comical. 

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Geos Proficient

Geos

Posted
Posted

Got highly filtered sun out there now. Hopefully the clouds can thicken up in the next few hours.

 

Mercer Island, 350 ft

2021-2022: 11.6", 02/21

2020-2021: 15.6"

2019-2020: ~10"

2018-2019 winter snowfall total: 29.5"

2017-2018: 9.0", 2016-2017: 14.0"

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Front Ranger Grand Master

Front Ranger

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Posted

Actually I have used it many times to gauge when precip will start or end even 18+ hours out and its usually pretty accurate. It can be a very good tool.

If you say so. Every time I've compared it to other tools it's not done well that far out. Just watch how much it often changes from run to run.

A forum for the end of the world.

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TT-SEA Grand Master

TT-SEA

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Posted

What does the flow turn from onshore to offshore ;) ? Give me wind directions if you are going to be adamant about trying to make a point. You're right it's not an opinion so let's look more closely. Here is the NAM 12z 12km showing onshore flow against the windward (west) side of the Olympics. Winds from the west against the west side of the Olympics. 

 

namconus_mslp_wind_nwus_14.png

 

The radar imagery at the corresponding time (and there after) show a textbook rain showing event. Dry air over the lowlands due to descending air over after the flow crosses the Olympics. So why does it start precipitating after this? The flow turns from west to south then finally east (offshore when the low is to the south). During the time when the flow is coming from a more southerly, direction this allow moisture transport to get into the Pugent Sound where the flow parallel to its structure and not obstructed by the Olympics.

 

 

 

 

You said the Olympics were the problem.   Its actually the Cascades and easterly flow that is the problem when the precip is occurring.

**REPORTED CONDITIONS AND ANOMALIES ARE NOT MEANT TO IMPLY ANYTHING ON A REGIONAL LEVEL UNLESS SPECIFICALLY STATED**

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