December 2016 Observations and Model Discussion for the Pacific Northwest

[SilverFallsAndrew]

Well, that isn't entirely true.  

 

That setup was more of an 11-19-03 on steroids.  There was no real dry advection, it was all about precip rates and relatively calm gradients.  The easterly drift helped, but it certainly wasn't the catalyst of that event as the outflow is this go around.  

 

Yeah very rare for Silverton to go from rain to snow in an overrunning type situation. 12/20/08 is the only time I ever remember that happening. 

[SilverFallsAndrew]

I should know better than to get into a disagreement with a lawyer, (married to one) but the moisture/radar returns are slightly ahead of schedule. Not saying that the precip looks to arrive at midnight now or anything but it could start closer to 8-9am rather than 11-1pm.

 

4pm forecast

Screen Shot 2016-12-07 at 3.38.31 PM.png

 

Radar return at 3:30pm

Screen Shot 2016-12-07 at 3.49.56 PM.png

 

I worry the dry air might eat the first hour or two of it...

[Deweydog]

I should know better than to get into a disagreement with a lawyer, (married to one) but the moisture/radar returns are slightly ahead of schedule. Not saying that the precip looks to arrive at midnight now or anything but it could start closer to 8-9am rather than 11-1pm.

 

4pm forecast

Screen Shot 2016-12-07 at 3.38.31 PM.png

 

Radar return at 3:30pm

Screen Shot 2016-12-07 at 3.49.56 PM.png

Ok

[SilverFallsAndrew]

EUG is going to end up with a midnight high of 36...

[MossMan]

18z GFS ensembles show shocking improvement...

Yay for the drunk uncles!!!! All of them!!!

Only hit 32 here at work! Down to 30 now.

[Prairiedog]

Yeah but I don't like crushing people's hopes. I'll still be hoping for a miracle!

Then we should cut back on the hyperbole.

[Timmy]

18z GFS ensembles show shocking improvement...

Pics or it didn't happen

[FroYoBro]

Getting pretty breezy here. I love getting east winds. 

[BLI snowman]

Welp, I'm gonna take my stab at it for my house...

 

1.25 inches with a 3:45 p.m. changeover (with a 10 minute margin of error).

 

I'll take it.

 

Only fly in the ointment is whether this will be a gorge-north snuff out setup. I've just never quite locked on how to spot one of those definitively. Since we're not in the wind here at the moment, I'm gonna discount it.

12/14/08 (or 12/24/1983) had a pretty strong downsloping component which killed Clark County's snow. Tomorrow looks like more of a classic gap wind (E or ESE) and not as much of a mountain wave orientation. I doubt we see a huge impact on our moisture.

[Front Ranger]

Gorgeous sunset in Seattle right now.

 

[BLI snowman]

But that kind of event is easier to pull off IMO without as much surface cold air to the east or already in place. 12/29/03 is a perfect example, gorge and basin temps were nothing to write home about. To me those kind of events are a totally different animal.

 

Those types of events are actually more rare, comparatively. It's harder to get widespread heavy snow here with minimal gorge assistance.

 

And wet bulb temps are very supportive of widespread snow and frozen stuff initially for the Portland metro, so I'm not sure why you're skeptical of the airmass being enough. It's marginal but it will easily support frozen precip.

[SilverFallsAndrew]

High of 32 at BLI today. Warning shot!

[BLI snowman]

Well, that isn't entirely true.

 

That setup was more of an 11-19-03 on steroids. There was no real dry advection, it was all about precip rates and relatively calm gradients. The easterly drift helped, but it certainly wasn't the catalyst of that event as the outflow is this go around.

We had enough dry air advection at the mid levels to drop temps appreciably. Temps bottomed out at 29-30 with the 1/27 storm, which isn't exactly borderline slop territory.

[Jesse]

18z GFS ensembles show shocking improvement...

I was just going to post about this.

 

Lots of support for the cold shot east side early next week.

[Kayla]

I worry the dry air might eat the first hour or two of it...

 

Yeah pretty typical in these setups.

[TT-SEA]

High of 29 here today... currently at 26.   

 

Dewpoint keeps dropping... down to 17.  

[Jbolin]

I've been pushed over the edge

[luvssnow_spokane]

Given how the ensembles continue to flip-flop on a near run-to-run basis, it's pretty evident the LR is in flux and the models don't really know what is going to happen.

 

The good thing is that potential is there for 'bouts of snow throughout the period. Best we can ask for at this point.

Oh brother... here we go again.

[Front Ranger]

High of 32 at BLI today. Warning shot!

 

Two sub-40 highs at SEA in the same month for the first time since Feb 2014. Bam!

[Heavy Snow]

Now the fun begins. We can start to follow the radar. Looks like moisture close to Roseburg.

[Brennan]

Two sub-40 highs at SEA in the same month for the first time since Feb 2014. Bam!

It is certainly progress.

[Timmy]

I was just going to post about this.

 

Lots of support for the cold shot east side early next week.

The 12z euro ensembles over half showed a blast into at least eastern wa and or.

[Skagit Weather]

Two sub-40 highs at SEA in the same month for the first time since Feb 2014. Bam!

They hit 40 yesterday didn't they? Or are you talking about tomorrow?

[Front Ranger]

They hit 40 yesterday didn't they? Or are you talking about tomorrow?

 

39 on Monday. 38 today. Tomorrow will make 3!

[Deweydog]

42/52 (81%) 12z Euro ensemble members show Seattle getting snow at some point past this Thursday/Friday.

 

34/52 (65%) show the same for Portland.

 

Those are pretty D**n good odds if you ask me.

 

Well why don't ensembles call/text the operational and tell it to get its in one bag.  

[MR.SNOWMIZER]

Millionaire

 

Well why don't ensembles call/text the operational and tell it to get its s**t in one bag.  

 

Millionaire

[MossMan]

Some big 00z's coming up tonight...hopefully everyone has refilled their Zoloft!

[Jesse]

Feels like snow out there!

[TT-SEA]

42/52 (81%) 12z Euro ensemble members show Seattle getting snow at some point past this Thursday/Friday.

 

34/52 (65%) show the same for Portland.

 

Those are pretty D**n good odds if you ask me.

 

 

Good information... thanks for the stats.   

[TT-SEA]

HRRR timing... precip into Portland at 11 a.m. and not really into Seattle until 7 p.m.

 

http://rapidrefresh.noaa.gov/HRRR/jsloopLocalDiskDateDomainZipTZA.cgi?dsKeys=hrrr_jet:&runTime=2016120721&plotName=1ref_t1sfc&fcstInc=60&numFcsts=37&model=hrrr&ptitle=HRRR%20Model%20Fields%20-%20Experimental&maxFcstLen=36&fcstStrLen=-1&resizePlot=1&domain=t1

 

It also shows snow in Seattle from roughly 7-11 p.m. tomorrow night and then turning to rain.

 

http://rapidrefresh.noaa.gov/HRRR/jsloopLocalDiskDateDomainZipTZA.cgi?dsKeys=hrrr_jet:&runTime=2016120721&plotName=1hsnw_t1sfc&fcstInc=60&numFcsts=37&model=hrrr&ptitle=HRRR%20Model%20Fields%20-%20Experimental&maxFcstLen=36&fcstStrLen=-1&resizePlot=1&domain=t1

[MossMan]

HRRR timing... precip into Portland at 11 a.m. and not really into Seattle until 7 p.m.

 

http://rapidrefresh.noaa.gov/HRRR/jsloopLocalDiskDateDomainZipTZA.cgi?dsKeys=hrrr_jet:&runTime=2016120721&plotName=1ref_t1sfc&fcstInc=60&numFcsts=37&model=hrrr&ptitle=HRRR%20Model%20Fields%20-%20Experimental&maxFcstLen=36&fcstStrLen=-1&resizePlot=1&domain=t1

 

So up to my area around 9pm...argh! Sure wish my daughter could go out and enjoy it before it turns to slop first thing Friday morning. Thursday morning into evening would have been perfect. Oh well. 

[Jbolin]

Some big 00z's coming up tonight...hopefully everyone has refilled their Zoloft!

Who needs Zoloft when you have this group of Ya-Hoo's 

[snow_wizard]

Some good news and some bad I guess would be the theme today.

 

1. ECMWF looks better for snow in the Seattle area on the 12z vs 0z for Thursday / Thursday night

2. Early next week looking shaky, but thanks to an inverted surface pressure setup we stay pretty chilly

3. Very good 18z GFS on balance

4. All models agree on very strong positive surface pressure anoms over the GOA next week

 

I think the biggest thing we have going for us next week is the HUGE area of 1030mb plus surface high pressure over the GOA. That feature makes a good outcome at least somewhat likely. Maybe we will have one or two failed attempts like the 18z shows and then strike gold. There is also still a chance the first round will hit us more solidly than is currently indicated. Most model runs are dangerously close either way. The really interesting this is the models depicts long lasting Fraser outflow next week in spite of a mediocre 500mb pattern. With 850s around -6 things could still be pretty cold with that.

 

I'm not even going to try to guess on tomorrow night at this point. I like how confident the NWS is for the East Puget Sound lowlands and the latest ECMWF is decent. In light of that we could see something worthwhile.

[snow_wizard]

As for precip timing tomorrow I would expect things to happen 2 or 3 hours faster than models predict. They always seem to be slow in situations like this.

[seattleweatherguy]

HRRR timing... precip into Portland at 11 a.m. and not really into Seattle until 7 p.m.

http://rapidrefresh.noaa.gov/HRRR/jsloopLocalDiskDateDomainZipTZA.cgi?dsKeys=hrrr_jet:&runTime=2016120721&plotName=1ref_t1sfc&fcstInc=60&numFcsts=37&model=hrrr&ptitle=HRRR%20Model%20Fields%20-%20Experimental&maxFcstLen=36&fcstStrLen=-1&resizePlot=1&domain=t1

 

It also shows snow in Seattle from roughly 7-11 p.m. tomorrow night and then turning to rain.

 

http://rapidrefresh.noaa.gov/HRRR/jsloopLocalDiskDateDomainZipTZA.cgi?dsKeys=hrrr_jet:&runTime=2016120721&plotName=1hsnw_t1sfc&fcstInc=60&numFcsts=37&model=hrrr&ptitle=HRRR%20Model%20Fields%20-%20Experimental&maxFcstLen=36&fcstStrLen=-1&resizePlot=1&domain=t1

Wow turns to rain before fri morning that fast

[Timmy]

Feels like snow out there!

Down to 26 here

[snow_wizard]

Wow turns to rain before fri morning that fast

That's always been expected. I suppose there is an outside chance we could go longer if the zone of low pressure stalls unexpectedly. Probably a shot at freezing rain in outflow areas also.

[snow_wizard]

I came up with a 38/24 high/low today. Certainly makes warning shot status.

[seattleweatherguy]

Ah bummer I guess it's an even longer shot to last through the weekend

[MR.SNOWMIZER]

I came up with a 38/24 high/low today. Certainly makes warning shot status.

33/26 here. Not to bad.