Winter Predictions

[snow_wizard]

Holy crap, that's amazing. Would require an 850mb temperature somewhere close to -28C, based on an elementary lapse rate extrapolation for diurnal maximum at that latitude.

 

That seems nearly impossible, but it almost has to be true unless there was a shallow layer of very cold air at the lower levels.

[snow_wizard]

Not many stations were recording in Western WA in the winter 1898-99, but Sedro Woolley (just south of Bellingham) paints an interesting picture.  They actually had 3 major cold waves that winter with a total of 20 max temps of freezing or lower with a decent amount of snow.  Normally a winter like that here would mean a torch in the East.  Just goes to show what is possible and in fact probably common during colder climate regimes.

[TigerWoodsLibido]

Not many stations were recording in Western WA in the winter 1898-99, but Sedro Woolley (just south of Bellingham) paints an interesting picture. They actually had 3 major cold waves that winter with a total of 20 max temps of freezing or lower with a decent amount of snow. Normally a winter like that here would mean a torch in the East. Just goes to show what is possible and in fact probably common during colder climate regimes.

You wonder how much longer it's going to be before the atmosphere re-configures into a similar pattern. You still think it's in a 50s-ish pre-winter pattern right now?

[snow_wizard]

You wonder how much longer it's going to be before the atmosphere re-configures into a similar pattern. You still think it's in a 50s-ish pre-winter pattern right now?

 

Yeah.  The anomaly center placement and intensity we saw with the two big troughs in the past month was certainly 1950ish.  There were some similar in the 1980s to mid 90s also.

[Black Hole]

That seems nearly impossible, but it almost has to be true unless there was a shallow layer of very cold air at the lower levels.

That would be my guess. Its fairly normal down there for the surface cold to outrun the upper level cold. Still pretty amazing though. Seems like a lot of snow cover over the path of the airmass would have been necessary too. 

[Phil]

That would be my guess. Its fairly normal down there for the surface cold to outrun the upper level cold. Still pretty amazing though. Seems like a lot of snow cover over the path of the airmass would have been necessary too.

How far can surface cold "outrun" upper level support in the middle of the day, over an Island in the Gulf of Mexico? I'd think the atmosphere would be pretty well mixed, especially over the warm Gulf waters, no?

[Front Ranger]

How far can surface cold "outrun" upper level support in the middle of the day, over an Island in the Gulf of Mexico? I'd think the atmosphere would be pretty well mixed, especially over the warm Gulf waters, no?

 

I can't speak for Galveston, but I know that surface cold often does outrun the upper levels with Arctic outbreaks across the Plains down into TX. A big part of the reason we often see Arctic fronts arrive here several hours before they were forecasted.

 

I'm guessing the topography of the plains has something to do with it.

[Guest happ]

I'm pretty sure CA will get an AR this winter.  Hard to say if it will get to So Cal or not, but it easily could.

 

Actually I was pleasantly surprised by the rain totals in NorCal/ North Bay late last week. Basically put out the fires; thanks Mother Nature. AR are so fickle but once in place can bring bountiful moisture. 

[Phil]

I can't speak for Galveston, but I know that surface cold often does outrun the upper levels with Arctic outbreaks across the Plains down into TX. A big part of the reason we often see Arctic fronts arrive here several hours before they were forecasted.

 

I'm guessing the topography of the plains has something to do with it.

Interesting stuff, thanks. I'm not familiar with mesoscale dynamics over the Plains. I'd just naturally expect a very well mixed lower boundary layer when frigid Arctic air runs into the Gulf Coast States. Doesn't mean I'm correct in that kind of thinking, though.

[Black Hole]

Interesting stuff, thanks. I'm not familiar with mesoscale dynamics over the Plains. I'd just naturally expect a very well mixed lower boundary layer when frigid Arctic air runs into the Gulf Coast States. Doesn't mean I'm correct in that kind of thinking, though.

I spend some time most years in Texas and I've seen it the last two times in winter when I have gone down where the lower level cold will move out ahead of the upper level cold. The lower boundary is probably well mixed, but due to its high density it seems to be able to hold together and remain separate from the warmer air above it.

And to speak to Front Rangers point. The terrain allows for some cold air damming which accelerates the lower level flow faster than it would otherwise move. 

[crf450ish]

[SilverFallsAndrew]

I spend some time most years in Texas and I've seen it the last two times in winter when I have gone down where the lower level cold will move out ahead of the upper level cold. The lower boundary is probably well mixed, but due to its high density it seems to be able to hold together and remain separate from the warmer air above it.

And to speak to Front Rangers point. The terrain allows for some cold air damming which accelerates the lower level flow faster than it would otherwise move. 

 

From my experience living in Oklahoma you are correct. The lower level cold air usually moves well ahead of the upper level cold. 

[TigerWoodsLibido]

Yup. That's why NE Texas experiences a lot of ice storms because that lower level air is indeed colder than aloft as you say.

[OKwx2k4]

From my experience living in Oklahoma you are correct. The lower level cold air usually moves well ahead of the upper level cold.

I live in practically the best cold air damming location in Oklahoma and this is an accurate description.

[Phil]

I always though cold air damming had to do with trapping low level cold, as opposed to funneling it in. At least that's how meteorologists view it around here.

 

Cold air takes forever to make it over the Appalachian mountains thanks to downsloping/adiabatic warming, but it's also very slow to evacuate, for the same reason(s). That's what we usually refer to as "cold air damning", as the mountains tend to "dam" the cold air in, much like a river dam does water.

[Front Ranger]

I always though cold air damming had to do with trapping low level cold, as opposed to funneling it in. At least that's how meteorologists view it around here.

 

Cold air takes forever to make it over the Appalachian mountains thanks to downsloping/adiabatic warming, but it's also very slow to evacuate, for the same reason(s).

 

Same here.

[TigerWoodsLibido]

I always though cold air damming had to do with trapping low level cold, as opposed to funneling it in. At least that's how meteorologists view it around here.

 

Cold air takes forever to make it over the Appalachian mountains thanks to downsloping/adiabatic warming, but it's also very slow to evacuate, for the same reason(s). That's what we usually refer to as "cold air damning", as the mountains tend to "dam" the cold air in, much like a river dam does water.

 

Same thing happens in the western Willamette Valley when we are in the icebox and a low pressure system overruns it.  The eastern outflow from the Columbia River Gorge toward the low center creates a cold air dam that pushes the column of cold air in the west valley higher, so as to delay or outright prevent freezing rain or sleet developing (such as what happened in 2008).  This is why places like Lebanon, Silverton and areas in the east valley have the warm nose affect them sooner with freezing rain/sleet or simply rising above freezing in the lower levels sooner than, say, McMinnville, Grand Ronde, Dallas, Monmouth/Independence, and sometimes even Philomath/Corvallis

[Kayla]

Here's Mark Nelsen's prediction, from his KPTV blog

 

He REALLY went out on a limb with this forecast...

[Phil]

How is 2016/17 on Mark's Niña list, while 2008/09 isn't? The system state was easily more Niña-esque overall in 2008/09 than it was last winter. Like, it's not even f**king close.

[TigerWoodsLibido]

Mark Nelsen relies way too much on the GFS and MOS guidance.  He was the worst forecaster for the 2008 event as he completely ignored the effects of the east wind cold air dam that kept the west valley in the snow much longer and it did not get above freezing while his forecast called for temps to rise to 48 degrees.  We didn't see the 40s for at least 3-4 days after that storm.  Easily had over 2' of snow on the ground in the west valley.  He made the same mistake last year in one of the early January events as Monmouth stayed in the snow for virtually the entire time Portland was being entombed in ice.

[Front Ranger]

How is 2016/17 on Mark's Niña list, while 2008/09 isn't? The system state was easily more Niña-esque overall in 2008/09 than it was last winter. Like, it's not even f**king close.

 

Agreed. 2008-09 produced a bunch of snow, though, so it didn't fit his weak/moderate Nina narrative.

[TT-SEA]

Mark Nelsen relies way too much on the GFS and MOS guidance.  He was the worst forecaster for the 2008 event as he completely ignored the effects of the east wind cold air dam that kept the west valley in the snow much longer and it did not get above freezing while his forecast called for temps to rise to 48 degrees.  We didn't see the 40s for at least 3-4 days after that storm.  Easily had over 2' of snow on the ground in the west valley.  He made the same mistake last year in one of the early January events as Monmouth stayed in the snow for virtually the entire time Portland was being entombed in ice.

 

I have seen Mark talk many times about how scouring out cold air can be very slow in the Portland area with east wind events and how the models often struggle in that situation.   Its really difficult to forecast.   He certainly understands how it works... he lives in the Gorge.   

 

Its tricky and destined to cause forecasting problems down there.   I have seen other times when he assumed it would stay cold and snowy and then it gets above freezing and there is nothing but cold rain.

[Jesse]

He REALLY went out on a limb with this forecast...

 

He's gotten older and crankier over the years. Summer warmth is by far his favorite thing to forecast these days.

[Deweydog]

Mark has developed a boring accuracy bias over the years. Definitely doesn't play well with the weenies. Oh the good ol' days of the 1990's when he'd go full nuclear with his seven day after a couple tasty GFS runs... Even in 2008 he I believe had at one point a seven day with at least five straight highs in mid 20'$. That's money!!!

[Front Ranger]

2017-18 Winter Outlook

 

Based on differently weighted factors and trends, including: ENSO, QBO, PDO, AO, NAO, EPO, NPI/Jim's index, solar, and overall pattern progression. 

 

Top tier analogs: 1954, 1970, 1984, 1989, 1996, 2000

Second tier analogs: 1956, 1962, 1974, 1981, 1985, 2007

Third tier analogs: 1949, 1961, 1967, 1971, 1995, 2013

 

More difficult winter outlook than normal, due to a lack of analogs without major holes, and fairly different timing of patterns depending on if November ends up warm or cold in the West.

 

IF November ends up cold in the West, I'd strongly favor 1956, 1961, 1971, 1985, and 2000. 

 

IF November ends up warm, I'd favor 1954, 1962, 1989, 1995, 2007 and 2013.

 

December

 

Strong signal for cold across the northern tier of the U.S., with the cold anomalies centered in the northern plains/upper Midwest. Warm across much of the southern tier. Anomalously high heights over the Aleutians, with the polar vortex likely spending some time in northern Canada. -1 to -3 anomalies predicted in the PNW, with northern areas likely to see the greatest cold. Decent chance this is the coldest month of the winter for New England.

 

January

 

Good signal for cold throughout the West, centered in the interior West/Great Basin. Expect NE Pacific ridging near the sweet spot for Arctic blasts offshore of North America, with the intensity of said blasts depending on amplification of the ridge. -2 to -5 anomalies predicted for the PNW. Under the influence of -EPO and perhaps weak -NAO, the rest of the country looks cool to near normal. Some moderation likely in the northern Plains.

 

February

 

Two main signals emerge this month: strong SE ridging, and a weakening of the -EPO, with strong ridging alternating between offshore and over the West coast. Expect most of the West to be below normal once again, but with the coldest anomalies shifting back to the northern plains. Warmth likely extends all the way up the east coast. Much of Canada is VERY cold. -1 to -3 for the PNW.

 

March

 

Hardest month to read by far, with not much in the way of meaningful signals. Moderation looks likely for the middle of the country, though the Northwest could easily remain cool. There is still some ridging in the NE Pacific, but also increasing likelihood of +EPO. The entire southern tier should be warm, especially the SE. 0 to -2 for the PNW.

 

Winter Temperature:

 

 

Precipitation:

 

There is an above average chance that this winter ends up drier than normal for much of the West Coast and northern plains. Near normal precip for the Great Basin/Rockies, and wetter than normal storm track along southern plains and lower Midwest, which should be the battle ground between warmth/cold.

[Phil]

Great analysis, man. Looks good to me.

[TigerWoodsLibido]

Would be pretty great for all of us in the PNW

[Front Ranger]

Great analysis, man. Looks good to me.

 

Thanks. Eager to see how November unfolds.

 

If you held a gun to my head now and demanded I provide a prediction for the month (this happens a lot), I'd lean towards it turning pretty warm for the West the second half of November, leading to an above normal month overall.

[Phil]

Thanks. Eager to see how November unfolds.

 

If you held a gun to my head now and demanded I provide a prediction for the month (this happens a lot), I'd lean towards it turning pretty warm for the West the second half of November, leading to an above normal month overall.

Interesting take. You might be right, assuming that anticyclone continues to retrograde into the Siberia/WPO area (which would fit with climo). I've been too busy to do much analysis on the pattern progression lately, unfortunately, so I have no idea what will happen.

 

I do see something in mid/late December, when the ongoing poleward propagation of AAM comes to a head over the Arctic/NAM domain, but other than that, I'm not sure.

[Kayla]

Thanks. Eager to see how November unfolds.

 

If you held a gun to my head now and demanded I provide a prediction for the month (this happens a lot), I'd lean towards it turning pretty warm for the West the second half of November, leading to an above normal month overall.

 

Thanks for sticking your neck out there and putting together this forecast. Looks great!

 

I'm honestly still liking the 1996 analog. Pattern progression has been pretty spot on for at least out here. Slightly below average October, below average November with above average precip and an average December with above average precip.

 

I'm thinking the west sees a brief ridge mid month before we go back into a similar pattern that we're in now by the end of the month.

[BLI snowman]

I think we torch at least one month this winter. December seems like it might be the best bet.

[Front Ranger]

I think we torch at least one month this winter. December seems like it might be the best bet.

 

I agree that if a month ends up warm, December is most likely. However, if November ends up pretty warm, I'd say it's pretty unlikely. Hardly any examples of that with -ENSO.

[BLI snowman]

I agree that if a month ends up warm, December is most likely. However, if November ends up pretty warm, I'd say it's pretty unlikely. Hardly any examples of that with -ENSO.

 

Also seems less and less likely judging from the next couple weeks.

[TigerWoodsLibido]

I agree that if a month ends up warm, December is most likely. However, if November ends up pretty warm, I'd say it's pretty unlikely. Hardly any examples of that with -ENSO.

 

We will be in the warm sector of the system next week and in the 50s so I guess that's right about normal.  Still a lot of November left.

[Front Ranger]

Also seems less and less likely judging from the next couple weeks.

 

A lot of uncertainty just past day 6 at this point.

[Phil]

Looking at the residual +QBO/westerlies at 50mb, and the huge swath of easterlies downwelling above it, I'm having a very hard time believing we won't see a major, low-frequency pattern shake-up sometime in December, perhaps around the winter solstice.

 

When the lower stratosphere flips modes, I suspect this NPAC wavetrain (poleward Aleutian anticyclone/-EPO) will either reshuffle somehow or collapse equatorward (from a seasonal-scale standpoint) as the convection/Z-Cells begin to respond. Exactly when/how this process unfolds is still unclear to me, however I'm target the period around the winter solstice, for the time being.

[Phil]

Looking aloft in the QBO/SAO boundary, the next period of downwelling should occur towards the winter solstice, at which point the lower stratosphere will join the upper stratosphere in the -QBO boundary state configuration. Whether coincidently or not, this is perfectly timed to the completing of the poleward AAM propagation cycle that began in September.

 

I'd give the westerlies @ 50mb another 7-8 weeks to live.

[Phil]

So, pattern wise, something big/anomalous should go down around the winter solstice/holiday period. Exactly what that may be, and how it unfolds, is still debatable (IMO).

[wx_statman]

Looking aloft in the QBO/SAO boundary, the next period of downwelling should occur towards the winter solstice, at which point the lower stratosphere will join the upper stratosphere in the -QBO boundary state configuration. Whether coincidently or not, this is perfectly timed to the completing of the poleward AAM propagation cycle that began in September.

 

I'd give the westerlies @ 50mb another 7-8 weeks to live.

 

Very interesting. We haven't seen a flip to -QBO @ 50mb in the Dec-Jan timeframe since January 1977. That was of course during the great reorganization of the Pacific background state.

[Phil]

Very interesting. We haven't seen a flip to -QBO @ 50mb in the Dec-Jan timeframe since January 1977. That was of course during the great reorganization of the Pacific background state.

The good news (from a PNW standpoint) is that the system's internal pendulum, so to speak, is on the other side now.

 

So there's only one way it can go, if pushed in the same manner it was back in 1977, and that's the other way. Or at least, that's my (oversimplified) opinion on the matter. It's probably a lot more complicated than that, in reality.