November 2017 PNW Discussion Thread

[Geos]

I have news coverage of this event on VHS that I taped at the time and will occasionally pull my VCR out of the closet and watch it...it was epic!! Another super memorable thing was the original forecast was perhaps a rain snow mix but nothing special...well I remember being at my grandparents house on Christmas evening and they always had the radio on in the background and I suddenly overhear that there was a major shift in the forecast and that a winter storm warning has been issued for Olympia north to the border...I no longer cared about any Christmas festivities and all focus was on getting home to my weather radio! It was magical!!!

 

That's cool you have a video to look back on.

 

Cliff Mass has a powerpoint with some December 1996 info in it. https://www.atmos.washington.edu/~cliff/Snowstorm2.ppt

 

Was hoping to find a snowfall map from that event. So far I haven't found any yet.

[DareDuck]

I still haven’t gotten as cold at my house in Bend as the Dec 13 event in Eugene. I’ve had several below 0 lows but haven’t hit -10 here. Weird to think my coldest low was in EUG and not Bend.

[luvssnow_spokane]

Some nice little Rabbit Snacks in some of the Euro and GFS Operational runs today... 

 

[TigerWoodsLibido]

Northerly wind into the valley on Black Friday. Interesting.

[Front Ranger]

I think he's recalling the valley wind shift which occurred around the 22nd with the surface low. His temp drop is exaggerated though.

 

Arctic fronts are rare around here for the simple fact upper air level changes rarely advect to the surface around here unless you have precip. And most of our strong cold advection events carry some form of downslope. You almost always need some manner of warm advection which is then going to slow things to a bleed thanks to topography.

Yeah, Nov 2010 was maybe the last solid one regionally?

 

Dec 1990 was an extraordinary beast.

[Jesse]

I think he's recalling the valley wind shift which occurred around the 22nd with the surface low. His temp drop is exaggerated though.

 

Arctic fronts are rare around here for the simple fact upper air level changes rarely advect to the surface around here unless you have precip. And most of our strong cold advection events carry some form of downslope. You almost always need some manner of warm advection which is then going to slow things to a bleed thanks to topography.

This is all true. But they used to be much more common.

[Timmy Supercell]

I still haven’t gotten as cold at my house in Bend as the Dec 13 event in Eugene. I’ve had several below 0 lows but haven’t hit -10 here. Weird to think my coldest low was in EUG and not Bend.

 

I had -20 on 12/08/2013, yet also had -19 just this last January on the 6th. Though of course the month of January wasn't nearly as anomalous as Dec 2013.

[Phil]

The d11-15 EPS is back to +PNA/+EPO with weak poleward fluxes. Would be temporary, but still icky while it lasts.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/644DC70F-41AF-4E38-8A09-DC2DBC30D9A1_zpsxtecpxlt.png

[TigerWoodsLibido]

This is all true. But they used to be much more common.

Back in the 50s-early 80s?

[Jesse]

Back in the 50s-early 80s?

The longest “dry spell” in recorded history has been from sometime in the 90s (depending on who you ask) until now.

[Phil]

Equatorial easterlies approaching 45mb now, so we're just about there. Only month or less until 50mb flips and shear starts declining. Will have to see how the tropical forcings respond over the next 5-8 weeks...crucial period starting during the second week of December.

[Jesse]

The d11-15 EPS is back to +PNA/+EPO with weak poleward fluxes. Would be temporary, but still icky while it lasts.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/644DC70F-41AF-4E38-8A09-DC2DBC30D9A1_zpsxtecpxlt.png

Yeah definitely looking like a crap pattern the next two weeks. Better now than later!

[HighlandExperience]

This is all true. But they used to be much more common.

Depressing. All of our recent arctic events feel like slow turtles

[Geos]

Noticed the GFS with hints of lowland snow on T-Day.

 

 

That is one large dump of cold air.

 

[Jesse]

Noticed the GFS with hints of lowland snow on T-Day.

 

The 12z GFS was completely off the Rez.

[BLI snowman]

I think he's recalling the valley wind shift which occurred around the 22nd with the surface low. His temp drop is exaggerated though.

 

Arctic fronts are rare around here for the simple fact upper air level changes rarely advect to the surface around here unless you have precip. And most of our strong cold advection events carry some form of downslope. You almost always need some manner of warm advection which is then going to slow things to a bleed thanks to topography.

 

I think he means 12/14/2008, which was a fairly impressive wind shift in the valley. Salem went from 40 to 31 in an hour.

[Deweydog]

I think he means 12/14/2008, which was a fairly impressive wind shift in the valley. Salem went from 40 to 31 in an hour.

Maybe so.

[MossMan]

Depressing. All of our recent arctic events feel like slow turtles

Been horribly annoying...every single one since 2012 has been a trickle that takes days to arrive and by then whatever snow that does fall melts before it gets cold enough. I miss the flash freeze days where the temp drops rapidly during the middle of the day during a dump of snow. Seems like that used to be the norm for Puget Sound...the new norm of these back door events is just painful.

[BLI snowman]

This is all true. But they used to be much more common.

 

I posted about this one in the newspaper archive but February 7, 1936 was another one that was extremely legit. Portland's temps went from 38 at 6am to 23 at 10am to 22 at noon to 16 by 7pm. The front that day also set Blaine's all time record low of -9.

[Tenochtitlan]

Been horribly annoying...every single one since 2012 has been a trickle that takes days to arrive and by then whatever snow that does fall melts before it gets cold enough. I miss the flash freeze days where the temp drops rapidly during the middle of the day during a dump of snow. Seems like that used to be the norm for Puget Sound...the new norm of these back door events is just painful.

Yeah, the only really impressive arctic front that I remember from all my years in Seattle is November 2010. That was like a mini blizzard, and as the roads rapidly froze up tons of people were stranded and had to abandon their cars. Even living in Bellingham the past few years, I still haven't seen anything quite like that, although last February was sort of close.

[TigerWoodsLibido]

Yeah, the only really impressive arctic front that I remember from all my years in Seattle is November 2010. That was like a mini blizzard, and as the roads rapidly froze up tons of people were stranded and had to abandon their cars. Even living in Bellingham the past few years, I still haven't seen anything quite like that, although last February was sort of close.

That 2010-11 year only ever had a 500' event in late February down here. Must have been a sharp temp gradient.

[Brian_in_Leavenworth]

Yeah, the only really impressive arctic front that I remember from all my years in Seattle is November 2010. That was like a mini blizzard, and as the roads rapidly froze up tons of people were stranded and had to abandon their cars. Even living in Bellingham the past few years, I still haven't seen anything quite like that, although last February was sort of close.

I used to live in the Bellingham area, and north County always had way more impressive winds and blizzard conditions than the greater Bellingham area.  I remember the local weather forecaster from KGMI would always draw the line north of the Smith Road as to the worst of the conditions.  

[Geos]

Been horribly annoying...every single one since 2012 has been a trickle that takes days to arrive and by then whatever snow that does fall melts before it gets cold enough. I miss the flash freeze days where the temp drops rapidly during the middle of the day during a dump of snow. Seems like that used to be the norm for Puget Sound...the new norm of these back door events is just painful.

 

That's what I'm used to also. Temp drop as the snow is getting going.

[Deweydog]

Warming climate?

[Jesse]

Warming climate?

Until next month!1

[TigerWoodsLibido]

Warming climate?

Yup, for thousands of years, actually. And also from Al Gore's SUV

[Jesse]

Yup, for thousands of years, actually. And also from Al Gore's SUV

I’ve heard a lot of conflicting information about the Medieval warm period, but some suggest it was about as warm 800-1000 years ago as it is today.

 

There certainly has been a net warming since the end of the Little Ice Age (~1850) to now, though. Albeit with a few hiccups.

[Deweydog]

Until next month!1

[Jesse]

The Dave Matthews Bland. Hopefully this winter will be a little more dynamic!

[Deweydog]

The Dave Matthews Bland. Hopefully this winter will be a little more dynamic!

I've heard EVERY month is supposed to be COLD. Doesn't sound too dynamic...

[Jesse]

I've heard EVERY month is supposed to be COLD. Doesn't sound too dynamic...

Dynamic in the context of the VERY warm years leading up to it and to follow!!

[Deweydog]

Dynamic in the context of the VERY warm years leading up to it and to follow!!

Well let's hope this winter is more along the lines of Creed or Nickleback.

[Front Ranger]

That 2010-11 year only ever had a 500' event in late February down here. Must have been a sharp temp gradient.

 

It still got pretty cold down your way. 

 

PDX had a 30/18 day on 11/23/10 and 33/18 on 2/23/11. I believe the February event was their coldest day on record that late.

[TigerWoodsLibido]

It still got pretty cold down your way.

 

PDX had a 30/18 day on 11/23/10 and 33/18 on 2/23/11. I believe the February event was their coldest day on record that late.

Makes sense. I think it was mostly dry cold. I was on the coast at that time so naturally I wasn't below freezing out there.

 

2013-14 was epic. -3 in Tillamook in Dec then mid 20s with blizzard conditions for 2 straight days in early Feb. 10" in Pacific City. Most since I moved to Oregon in 1989.

[MossMan]

Makes sense. I think it was mostly dry cold. I was on the coast at that time so naturally I wasn't below freezing out there.

 

2013-14 was epic. -3 in Tillamook in Dec then mid 20s with blizzard conditions for 2 straight days in early Feb. 10" in Pacific City. Most since I moved to Oregon in 1989.

For up this way not much has come close temp wise to the -2 I had at my house (-4 in Arlington if I remember correctly) on the morning of Dec. 20th 2008. I think we got down to near zero in the late 70’s (think it was in January) but I was only around 3 or so years old so that one is a little hazy. Upper single digits has been slightly more frequent like Nov 1985, Nov 2006, and Dec. 2009. Just to name a few but that morning in Dec. 2008 was something else up here!

[Phil]

I’ve heard a lot of conflicting information about the Medieval warm period, but some suggest it was about as warm 800-1000 years ago as it is today.

 

There certainly has been a net warming since the end of the Little Ice Age (~1850) to now, though. Albeit with a few hiccups.

The Medieval Warm Period is still a huge challenge to figure out for the paleoclimate community, and yeah the debate over the magnitude of the warming is far from settled, given the conflicting proxy data (which you mentioned). It's very debatable whether it was only the NH that was as warm (or warmer than) today, or if it was the entire globe.

 

Certainly, most evidence suggests that the Arctic, North American, and European domains, in particular, were actually warmer than today for a period lasting about 250yrs, however that warming was locally exaggerated due to a persistent long period +NAO cell, so the actual "global warming" was *less*, relatively speaking. Still, tree-lines were higher across most of the NH during the Medieval Warm Period, and some glaciers that are retreating today did not exist at all during the MWP.

 

Also, contrary to the "shorter term" climatic responses to ENSO we observe today, the Medieval Warm Period was dominated by a very strong -PDO/La Niña cell and expanded WPAC warm pool, similar to the WPAC cell we observe today. So the tropics were about the same temperature (or cooler) during the MWP as they are today. It's still a mystery whether La Niña (strong tropical Pacific heat pump) was responsible for the Medieval Warm Period by advecting an excessive load of heat into the extratropics through the WPAC warm pool, or whether it was, in fact, a negative feedback response to tropical heat buildup/global warming following the dark ages cold period, in which case the La Niña state would have helped expel heat from the tropics, and send it poleward.

 

Then again, the strong +NAO/+NAM indicates *reduced* deep tropical convection as a whole, in which case the BDC/mass circulation would have been weaker, and both tropical cloud cover and wind speeds would have been reduced substantially. So, in the La Niña might simply have served to expel tropical heat buildup into the extratropics/poles, during a global warming regime, which would have super-amplified the warming in the higher latitudes and weakened it at the lower latitudes.

[Phil]

What's bizarre is the warmest long term climate periods always seem to bias towards La Niña, and the coolest always seem to bias towards El Niño. The middle Holocene (5-8krs ago) was the warmest climate period since the Eemian, 125kyrs ago), and the system state was the most La Niña esque of any period in the observable proxy record.

 

So, is ENSO a negative feedback that serves to dampen climate changes? Or does it cause climate change by altering the nature of heat uptake/release? Certainly the Niña periods seem to kick in after warming has already commenced, and seem to flatten out the temperature trends, but given El Niño dominated during the last ice age and during the heart of the more recent "little ice age", it's tough to say. We entered into another La Niña dominated regime during the end of the LIA, about 25-40yrs after the planet had resumed its warming trend, so whether that assisted the process or was a negative feedback is debatable.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/39650A2B-70AA-4346-831F-12E47C192C3D_zpsfuhaz2aj.jpg

[Jesse]

Fascinating stuff Phil.

[Jesse]

Looks like snow is finally falling at Government Camp. This has been a very slow moving frontal band, they have been dry in the Oregon Cascades most of the day while the Washington Cascades have been getting hammered.

[Phil]

The La Niña dominance that asserted itself in the early 1800s likely occurred *after* the start of global warming, which was probably around 1700. That would suggest that it's a negative feedback response to WPAC heat buildup, but it's not clear cut.

 

Oceans everywhere, including the NPAC and Indian Ocean, began warming around 1700, and warmed substantially over the next century, up until about 1800.

 

The warming from 1700-1800 is one of the most overlooked abrupt climate changes in modern history. It's especially shocking considering how recent it was, relatively speaking.

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/55F1CCAE-4F03-4E1F-B333-AE3408A5B6AF_zpskv5b81le.jpg

 

http://i724.photobucket.com/albums/ww243/phillywillie/Mobile%20Uploads/1002B100-91D7-4870-B4FD-85139D1A97C3_zpslpocvecc.jpg