Winter 2019-20 Preseason Discussion

[CAPE]

1 hour ago, showmethesnow said:

EPS is hinting at the possibility of southern/coastal low at the end of the extended (roughly a 1/4 of the members are seeing it). Really not worth breaking it down into detail but we are seeing neg temp departures at that time. Whether they would be cold enough is another story. Snow maps do have a handful of members or so that show something (mostly mood flakes) in the general region. One member would win the hearts of many in here as it is generally a region wide 6-10"s.

I took a quick glance at h5 on the EPS this morning and saw the negative height anomalies down south towards the end of the run and was like hmm...that looks interesting, and how nice to see the antithesis of a SE ridge. Hopefully we see more of that look going forward.

[frd]

52 minutes ago, losetoa6 said:

Yea...definitely something to keep an eye on. The neat thing about those 2 members from Gefs, Eps is they're exactly the same time frame almost to the hr. lol. Nice banana high with both as well

 

Tasty 

 

 

[CAPE]

Both the EPS and GEFS have the AO and the NAO turning negative for early November. Again lets see how this plays out, and whether it means anything further down the line wrt persistence.

[frd]

Euro monthly interesting with a disrupted PV further into the month of Nov. Also, as mentioned by HM recently, a couple drivers are present to provide stress to the PV  

I like seeing the  Aluetian Low - Scandinavia High combo later in November showing up. Matt Hugo  is all over this.  Meanwhile, we have the QBO continuing to descend,  rapidly building snow cover across the entire NH and low solar min with short-term quiet condition continuing,  all in our favor currently.  I like what I am seeing and starting to get just a bit excited for the prospects of holiday cheer. 

 

[WxUSAF]

Ontario and Quebec look to her thoroughly snow covered over the next week or two and temps will stay cold up there per guidance , so it should stick around. Good news for keeping air masses cold as they head our way. 

[psuhoffman]

13 hours ago, Maestrobjwa said:

Man, now on this? I still can't buy the theory that it could've been better that year...because that year did what most la ninas that aren't 1995/96 seem to do: snow all around us, lol Was that not more the typical NS issues than luck?

La Nina’s climo does show a snow anomaly minimum over our area. But it’s not nearly as localized as the snow hole that year was.  

[frd]

43 minutes ago, WxUSAF said:

Ontario and Quebec look to her thoroughly snow covered over the next week or two and temps will stay cold up there per guidance , so it should stick around. Good news for keeping air masses cold as they head our way. 

Seems in the process the Hudson Bay vortex moves further South , more so than typical. Maybe an indication of an eventual discharge of very cold air down our way in early to mid December.

Speaking of December -  

 

  

[40/70 Benchmark]

5 minutes ago, frd said:

Seems in the process the Hudson Bay vortex moves further South , more so than typical. Maybe an indication of an eventual discharge of very cold air down our way in early to mid December.

Speaking of December -  

 

  

Yea, not buying a slow start....have had my mind made up on that.

[Winter Wizard]

19 hours ago, BTRWx's Thanks Giving said:

I think November can be just as important (if not more) relative to the rest of winter.  Could you run those numbers when you get a chance? 

Since 1950, there has been a -AO in November 38 times. Among those 38, 23 were also followed by -AO in December, but 27 featured a mean -AO for DJF. The average snowfall since 1950 at DCA is 16.1".

Among those 38 Novembers, 23 had a strong -AO of <-0.5. 16 of those years (70%) also had a -AO for the winter. Interestingly, the last four times this occurred (2018, 2016, 2014, 2007), there was a +AO in the winter.

Conversely, there have been 17 Novembers with strong +AO of >0.5. 11 of the following winters (65%) also had a +AO.

The mean snowfall in -AO November years is 15.2", but in strongly negative years (<-0.5), the average climbs to 18.4". -AO Novembers where the winter also featured a -AO DJF have a mean snowfall of 17.7".  In total, 12/38 (31.5%) of -AO November winters had above normal snowfall.

Interestingly, the mean snowfall in +AO November years is above normal at 17.2". 13/31 of those winters featured above average snowfall (41.9%).

Another interesting tidbit I found was in DC's top 10 snowiest winters, 5 of them had a -AO November, but only 2013-14 had a +AO November and +AO winter.

[CAPE]

2 hours ago, Winter Wizard said:

Since 1950, there has been a -AO in November 38 times. Among those 38, 23 were also followed by -AO in December, but 27 featured a mean -AO for DJF. The average snowfall since 1950 at DCA is 16.1".

Among those 38 Novembers, 23 had a strong -AO of <-0.5. 16 of those years (70%) also had a -AO for the winter. Interestingly, the last four times this occurred (2018, 2016, 2014, 2007), there was a +AO in the winter.

Conversely, there have been 17 Novembers with strong +AO of >0.5. 11 of the following winters (65%) also had a +AO.

The mean snowfall in -AO November years is 15.2", but in strongly negative years (<-0.5), the average climbs to 18.4". -AO Novembers where the winter also featured a -AO DJF have a mean snowfall of 17.7".  In total, 12/38 (31.5%) of -AO November winters had above normal snowfall.

Interestingly, the mean snowfall in +AO November years is above normal at 17.2". 13/31 of those winters featured above average snowfall (41.9%).

Another interesting tidbit I found was in DC's top 10 snowiest winters, 5 of them had a -AO November, but only 2013-14 had a +AO November and +AO winter.

We knew that winter was a fluke as it was happening. Ton of luck, and the -EPO/WPO drove it and brought the cold. Likely the only way to overcome a sustained +AO during winter around here.

[frd]

With all the talk about using only recent analogs and all the repeating warm Decembers periods, especially later in the month, as HM brings up post 12/20 ,   I found this post enlightening. 

Wonder if this year we buck the trends and persistence of the post 12/20 period? 

So, looking at the data -  Nina-like is a chillier December and Nino-like warmer, makes sense. This year though we have a variety of drivers, how they interact will be very interesting.  

 

 

[frd]

Sea ice recovery update from Bring Back over at 33andrain below. 

Nice to see this robust recovery ( off of all time lows )  and goes along with rapidly building NH Snow cover.  Bring Back, ( David ) does a great job at explaining everything about sea ice. 

IMHO my take on this right now is a robust cryosphere is developing and this raises the possibility that in the next couple of months a severe arctic outbreak is possible in the East.   

from David : 

<<<<<<

Another 250,000 sq km of new ice yesterday!  Right now the record rate of 1 m increase every 4 days persists!  While this incredible rate cannot be sustained much longer, I do feel that 2019 will exceed 8 m sq km by this weekend and that will put it ahead of 2012, 2018, 2007 and 2017 in that order (with 2016 passed yesterday) and not far off 2010.  In other words 2019 over just 2 weeks will recover from by far the lowest extent to exceed the decadal mean.

 

I should add (as I do in my longer posts) that this does NOT mean that the overall 2019/20 winter Arctic ice extent will end up any better than in other low extent recent years. Let's hope that the conditions remain conducive for a continued strong recovery.

The express recovery rate continues:

 

 

>>>>>

 

 

[frd]

Watched a great webinar about the upcoming winter featured  by BAMMWX

I took some notes while watching -  was an awesome presentation. I did the best I could writing down the most important points.  

Analogs temps:    77/78  79/80  03/94   95/96  04/05

Analogs precip :   95/96  77/78  79 /80  93/94

Main warmer risk is that the Eastern ENSO areas warm up from the current levels. 

Month with the least confidence, December. Most confidence in Jan., Feb and the shoulder month March. ( cold, active, snowier ) 

Last years SH SSWE caused the SA Easterly wind signal and warmed the Eastern ENSO and impacted the winter . Impacted the MJO and the Jet. 

There is an association with SH's weather events/ SSWE , etc. and the effects on the MJO phase and movement in the Western Pac and the Maritime continent 

BAMMWx expects more phasing potential this year in the East, more STJ , etc. Biggest concern here the STJ outruns the PJ but they believe that will not be the case this winter.

Can't ignore the last 18 years worth of Decembers,  but there are significant signals that this December could be cold ( just be aware the ENSO argues against it to a degree, versus other factors that support it  ) 

Early Season PV formation, shape and location are conducive to the delivery of cold air masses over the US. Different than other past early season PV.

Solar min very significant , Sept 2019, lowest sunspot number since 1901. 

QBO, during the past 7 days has descended more than the past two months. QBO phase and shear favorable for cold in the East

Interesting note that this year argues against splits but a weakened more elongated PV is favored. Also, the current location over Canada may be very hard to move and may favor our side of the pole.  Other thing to consider robust NH snow cover. Able to deliver fresh arctic air masses into the NE 

Neutral ENSO combined with a + IOD leads to a cold East ( 3 rd most + IOD at this time ) 

 + QBO  at 50 mb lessens the MJO or keeps it closer to phases 8 , 1 and 2, much different than last year. Cold winter phases are most likely . This is already happening

According the BAMMWX  the PDO is not the biggest driver.

+ PMM although not as positive recently,  there is still a very strong signal for a tall North Pacific ridge and a trough in the East  in December. There is also the association of a more enhanced STJ as well. Can enhance phasing as well. 

Overall BAMMWX going with a colder December and  a generally cold and snowy winter forecast. 

Some other notes - 

ENSO set up - most important is the placement of the warmer and cooler anomalies -  currently Warmer West , much cooler Easter regions. 

Latest data, sub surface warmth increasing in the Western areas 

ENSO is the main factor against a cold December in the East 

Kirk mentioned he expects a change in the weeklies soon, and that many times the reason the Euro weeklies and seasonal do so poorly is a poor initialization  

CFS HDD doing a lot better 

EURO with a 8 to 14 point warm bias days 9 to 14

 

[WxUSAF]

I don’t think you can use old analogs (pre-2000? But certainly pre-1990) without accounting for the background climate warming. Maybe they did that, but when i see these old analogs I get skeptical.

[WinterWxLuvr]

I think December can be a hard month to judge by avg temp. You can have a month that is predominantly cold or seasonal and have the avg temp skewed by a few days of anomalous warmth. December can crank out some pretty big temp departures in the positive direction. So saying an above normal December doesn’t necessarily mean it couldn’t also be a mainly wintry month

[CAPE]

So as October comes to a close, what is the verdict on the SAI? Have we met the criteria for rate of change of snow cover for Eurasia south of 60N? What shall we expect as a result for the winter AO state? PV weakling or big blue ball locking up all the polar air well north? Will Cohen take credit regardless? All questions inquiring minds need answered.

[psuhoffman]

1 hour ago, C.A.P.E. said:

So as October comes to a close, what is the verdict on the SAI? Have we met the criteria for rate of change of snow cover for Eurasia south of 60N? What shall we expect as a result for the winter AO state? PV weakling or big blue ball locking up all the polar air well north? Will Cohen take credit regardless? All questions inquiring minds need answered.

What would you do if you were stuck in one place and every day was exactly the same, and nothing that you did mattered?
That about sums it up for “Cohen”.

[PCT_ATC]

12 hours ago, psuhoffman said:

What would you do if you were stuck in one place and every day was exactly the same, and nothing that you did mattered?
That about sums it up for “Cohen”.

[WxUSAF]

Cohen says snowcover advance index supports -AO! Here we go!!!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

#sarcasm

[psuhoffman]

58 minutes ago, PCT_ATC said:

Don’t drive angry 

[frd]

Continued downward 

 

[Maestrobjwa]

7 minutes ago, frd said:

Continued downward 

 

Again which begs the question...will the benefits lag until NEXT winter...or will we already feel them this year?...

[MountainGeek]

3 minutes ago, Maestrobjwa said:

Again which begs the question...will the benefits lag until NEXT winter...or will we already feel them this year?...

Depends on the lag duration....on the positive side: solar was very low last year as well so if there's, say, a 1 year lag, we're getting any benefits now and next winter might get even more "help" in that area. If there's not a lag, then we're getting any benefits as we go in real time. All good, right? 

But remember it's never only one factor -- the ultimate winter outcome is a combination of dozens of known factors (and maybe even more that we still don't fully understand yet). And of course the possible links between low solar, HL blocking, colder winters, etc are still being explored, so no guarantees. 

[rclab]

5 minutes ago, MountainGeek said:

Depends on the lag duration....on the positive side: solar was very low last year as well so if there's, say, a 1 year lag, we're getting any benefits now and next winter might get even more "help" in that area. If there's not a lag, then we're getting any benefits as we go in real time. All good, right? 

But remember it's never only one factor -- the ultimate winter outcome is a combination of dozens of known factors (and maybe even more that we still don't fully understand yet). And of course the possible links between low solar, HL blocking, colder winters, etc are still being explored, so no guarantees. 

I like your explanation. Sadly it makes picking the correct 5 + 1 for mega and power ball look easy. As always ......

[MountainGeek]

40 minutes ago, rclab said:

I like your explanation. Sadly it makes picking the correct 5 + 1 for mega and power ball look easy. As always ......

Thanks -- don't forget to mix in general atmospheric chaos/butterfly effect, a VERY short recorded data timespan (relative to all of past history).....trying to predict longer term and seasonal weather has lot of parallels to picking numbers or trying to "game" a slot machine. Quite a few of the folks who participate in this forum enjoy hitting the casino as well...I don't think that's a coincidence. And the nice thing about weather is when it pulls the rug out from under you, you only suffer a hit to your pride and not your pocketbook. 

[pasnownut]

2 hours ago, WxUSAF said:

Cohen says snowcover advance index supports -AO! Here we go!!!

 

#sarcasm

while that may be a bit leading/presumptuous....I'd sure rather have explosive snowcover than warm barren tundra.

#maybemaybenot 

[frd]

QBO looking good so far 

 

 

[Bob Chill]

Hey weenies, figured it would be exceptionally strange for me to not post in the winter thread during Oct so....

TL:DR: Favorable enso is close to off the table. I have no ides if the AO/NAO will cooperate. The north Pac ssta's are moving in the direction of what we want to see but plenty of work to do over the next month. This could be a sign that the Pac jet won't destroy our hopes and dreams and there's no reason at all to think we're F'd yet. My confidence in any outcome is very low still.

I have no opinion on QBO/blocking/strat PV etc yet but I am warming up to the idea that this winter may not be a total disaster. Enso probably won't drive the bus as it's pretty late and the enso regions are ambiguous imo. Numerical data for region 3.4 looks ok but I'm more of a visual person when assessing the influence of the eq Pac and right now it just doesn't look all that great. Region 3.4 warmth seems more of a byproduct of the pac having expansive warmth north of the equator in general and not due to circulation patterns responding to nino forcing.

In early Sept I thought the pac nino and pdo regions looked like trash. This is not a ssta map that inspires confidence in a good winter in the mid atlantic:

 

I havent been paying much attention to what others have been saying but if enso isn't going to do much then the next best thing is to have a +PDO. The PDO is what helped make the 2013-16 winters favorable. It may have been the primary reason. Hard to say. It's also what made 95/96 a prolific nina. A +pdo during a nina is very uncommon. Especially a mod+ Nina. When I looked at the ssta map in early Sept my first thought was the PDO region looked like crap. Not as bad as a -pdo but pretty bad.

Over the last 2 months the PDO region has improved. Not as fast as I'd like but it's better. The area off the coast of Japan needs to cool down but you can see the expanding region of BN ssta's in the western pac compared to early Sept. Hopefully that keeps building eastward. It could be the first clue as to what the predominant pac jet structure ends up being this winter.

 

We only have 14 real weeks of winter and it goes quick. As we've seen recently and countless times in the past, the pac jet is a big deal here and get it wrong for a month and you can kiss half or more of winter goodbye regardless of all other indices. The problem is there is no way to know what the jet is going to do weeks or months in advance. Especially during transition months like Nov and early Dec. However, if Nov features a trough in the west pac and a ridge in the east pac centered near the west coast it's going to push the pdo region into a configuration that can be really friendly here. It would also increase our chances of getting off to a good start in early Dec. If there is a persistent good pac pattern in Dec it's entirely possible it will recur throughout met winter. 

It's a chicken or egg argument though just like "the blob" in 2013-15. What causes what? Do the ssta temps force the troposphere or does the trop force the ssta's? IMO it's a little bit of both. Weather patterns force the ssta's and once the warm and cool anomalies are well established they can assist with persistance. 

Gun to head this winter will be close to average in both temps and snowfall and the odds of +climo snowfall are slightly higher than an epic fail. I'm expecting the -EPO to flex at times and I doubt we'll get SE ridged to death.

 

[jaydreb]

Oh boy, must be close to showtime if Bob is here.  Great to have you posting @Bob Chill!  

[WxUSAF]

Good to see you, friend. Seems like this winter could feature many of the things we’ve seen a lot this decade. -EPO driven cold shots, predominantly +NAO, variable AO, and moisture around. So like most winters this decade, we probably will get a lot of nickels and dimes and maybe if we’re lucky a Susan B. Anthony or two.