Winter 2019-20 Preseason Discussion

[CAPE]

Looks like the SPV will undergo some perturbation/elongation after an apparently brief strengthening. GEFS has the TPV on our side of the pole in the long range with surface pressure building up top in the AO domain. Current CPC forecast has the AO trending negative after the first week in Nov. Lets see how this plays out, and if it verifies, does it actually become a  sustained feature going forward.

[LurkerBoy]

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

Looks like the SPV will undergo some perturbation/elongation after an apparently brief strengthening. GEFS has the TPV on our side of the pole in the long range with surface pressure building up top in the AO domain. Current CPC forecast has the AO trending negative after the first week in Nov. Lets see how this plays out, and if it verifies, does it actually become a  sustained feature going forward.

What happens if it becomes a sustained feature?

[CAPE]

7 minutes ago, LurkerBoy said:

What happens if it becomes a sustained feature?

In general, more persistent/frequent cold air excursions into the mid latitudes, and increased prospects for snow in the MA.

[midatlanticweather]

 

[frd]

2 hours ago, C.A.P.E. said:

Looks like the SPV will undergo some perturbation/elongation after an apparently brief strengthening. GEFS has the TPV on our side of the pole in the long range with surface pressure building up top in the AO domain. Current CPC forecast has the AO trending negative after the first week in Nov. Lets see how this plays out, and if it verifies, does it actually become a  sustained feature going forward.

Loving the  build up of snow ! Bring it on !  

Nice visual and even signs of a sea ice recovery. Of note,  the area North of Alaska is cooling.  Implications for the late December and Jan pattern. 

I could speculate we are going to end the month on a high note, and only continue to build from there in early November. 

 

 

 

 

[frd]

@C.A.P.E.

Not very scientific, but comparing week 39 in 2019 to week 39 in 2009.   

Generally speaking we are doing well. No associations are being made, except the backdrop of a low solar min.   

If, we can get sea ice to bounce back to a degree, and it should in the next 7 to 14 days,  might be interesting weather around these parts later in the year.      

 

Row	Year	Week	N. Hemisphere	Eurasia	N. America	N. America (no Greenland)
1	2019	39	8.91	3.52	5.39	3.24

 

523

2009

39

6.29

1.21

5.08

2.93

 

[frd]

3 hours ago, C.A.P.E. said:

Looks like the SPV will undergo some perturbation/elongation after an apparently brief strengthening. GEFS has the TPV on our side of the pole in the long range with surface pressure building up top in the AO domain. Current CPC forecast has the AO trending negative after the first week in Nov. Lets see how this plays out, and if it verifies, does it actually become a  sustained feature going forward.

Hearing a lot of conflicting comments on the PV. 

Taken from John going very strong, of course, how strong it verifies is not certain.  

The GFS portrays what @C.A.P.E. mentioned.

HM chimes in wisely and takes into account some things the average person doesn't focus on,  as well as a previous good read.

Here are some of the latest thoughts on this. 

 

 

Little sensational if you ask me. 

 

then from HM 

 

 

Anthony Masiello @antmasiello  2h

 

Replying to

@jhomenuk

The shape of the polar vortex is just as, if not more so, important than u-wind strength... especially during the early season when it's normal to strengthen.

 

John Homenuk @jhomenuk  2h

 

Agreed 100%, and still think there is a degree of uncertainty in anomalous the u-wind gets too. But as you alluded to, many different layers to the actual impact of a strong spv including its shape and location. From a u-wind perspective, forecasts are impressive tho

 

A nice refresher from HM

 

 

 

[CAPE]

Cohen is a sensationalist and seems to always be rooting for the extreme. He is like a one-trick pony version of Bastardi. We don't need  SSWE and PV splits, we just need the damn thing in a weakened state so all the cold doesn't stay bottled up in the high latitudes.

[frd]

5 minutes ago, C.A.P.E. said:

Cohen is a sensationalist and seems to always be rooting for the extreme. He is like a one-trick pony version of Bastardi. We don't need  SSWE and PV splits, we just need the damn thing in a weakened state so all the cold doesn't stay bottled up in the high latitudes.

Please don't think because I put Cohen up there I endorse him, I certainly do not . But, I do endorse the potential that the PV will be put under pressure in some form or fashion as November moves on.  Simple referring to the potential warming. I do not want to see a SSWE either and will be perfectly happy with a weak PV. 

 

 

[CAPE]

15 minutes ago, frd said:

Please don't think because I put Cohen up there I endorse him, I certainly do not . But, I do endorse the potential that the PV will be put under pressure in some form or fashion as November moves on.  Simple referring to the potential warming. I do not want to see a SSWE either and will be perfectly happy with a weak PV. 

 

 

I don't think you endorse him lol. I am sure there are many people who think his work is useful, but I find his shtick to be a complete bore.

I never go out of my way to read his stuff, but when I see something here or elsewhere from him, it's mostly the same old broken record.

[frd]

Great read brought over from 33andrain

The met there hits on everything we have been  talking about. 

Enjoy 

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Posted 1 hour ago

I'm going to try to post a final outlook of sorts within the next week along with a longer commentary...no huge changes to my thoughts, though did make it a bit colder in the east.  In the meantime, I do have a few general thoughts based on what I've been seeing here and on #WxTwitter. 

 

The PDO right now is very close to neutral.  The September value from NCDC was 0.00.  I've highlighted in blue areas that would suggest a negative PDO, and in red areas that would suggest a positive PDO.  It remains very close to neutral, and the "cold" waters near the West Coast aren't particularly cold.  I look at it as a neutral PDO but with a highly anomalously warm North Pacific.

 

 

If anything it may trend a little more positive over the next few weeks, but not enough to really move the needle IMO.  For reference, here's the JISAO plot of a negative vs positve PDO:

 

 

I guess my point is that while it's not a classic +PDO, it's definitely not "tanking" and will likely be close to neutral for the winter barring some fairly substantial changes.  I also want to stress that the little sliver of cooler water near the West Coast has no ability to force a pattern in the future.  It's more a reflection of the pattern we've seen frequently since September.  It's possible that pattern is a sign, but the SSTs themselves don't force anything (it's a small area of near average SSTs in an area where SSTs are too cold to strongly force anything).  For instance, the ridge over the next 10 days doesn't seem to mind the little bit of cooler water near the coast:

 

 

 

The 6-10 day 500mb in winter (even without  longer wavelengths) would already by a pretty chilly and active pattern from the Ohio Valley into the northern Mid-Atlantic and New England.

 

With regards to the western US trough and SE US ridge, I still think it's way too early for it to cause any concern for winter.  We just had an exceptionally long-lasting and amplified phase 1 RMM (it was more of a standing wave than true MJO, but registered as a phase 1 MJO).  It was in "phase 1" for nearly a month and didn't come close to the "circle of death":

 

 

When the RMM is phase 1 in the fall it correlates to warmth in the eastern US and cold in the west, which is what we've seen plenty of.  Wavelengths are beginning to quickly get longer as we transition to winter...this same forcing would result in a different pattern in winter.  Compare the September-November phase 1 temperature correlations to the December-February ones....basically, a SE ridge is what we'd expect with the tropical  forcing we've seen and it's what we've gotten.  In winter the same tropical forcing on its own supports a much colder outcome for the eastern US:

 

 

The ongoing and near term intensification of the stratospheric polar vortex is of some concern if it continues unchecked well into November...the upcoming pattern is literally the opposite of what we want for PV disruptions with an Aleutian Ridge and Scandinavian Trough, so it's no surprise we're seeing impressive intensification, which could well lead to a spell of milder weather around the middle of November:

 

 

With some hints of a +EAMT during week 2 and some ridging developing over Scandinavia...with the CFS and EPS weeklies hinting at some Pacific tropical forcing returning during November to go along with impressive Siberian snow cover supporting a stronger Siberian high, there are ways to disrupt the PV going forward.  We'll see if anything comes to fruition.  The lack of a classic Aleutian low thus far is likely a part of the longer running -GWO, and if that continues then Wave 1 disruptions may be limited (a Scandinavian ridge is usually wave 2).  Most of the analogs that have the most blocking have an Aleutian low by October or November which can disrupt the PV via Wave 1 forcing, so this is going to be interesting to watch and see if we can get enough disruptions elsewhere.

 

Long story short, I still generally like where we sit, but if we don't see disruptions to the PV resume in November then the prospects of a warmer December with a +AO increase.

 

>>>>>>

 

[Maestrobjwa]

Did someone say a +AO in December was a bad sign for the winter as a whole? @psuhoffman I remember last year you mentioned something about a +AO December being a bad thing once...but I can't remember whether you were talking specifically for whatever winter you were referring to, or in general)

[aldie 22]

So today is a not so good pretty good day?

[mattie g]

5 minutes ago, leesburg 04 said:

So today is a not so good pretty good day?

If an October day doesn’t have a high of <50 and isn't raining (or both), then it sucks.

[Maestrobjwa]

10 minutes ago, leesburg 04 said:

So today is a not so good pretty good day?

Man do you come here just to do that? Smh

[aldie 22]

42 minutes ago, Maestrobjwa said:

Man do you come here just to do that? Smh

Yes?

[Winter Wizard]

1 hour ago, Maestrobjwa said:

Did someone say a +AO in December was a bad sign for the winter as a whole? @psuhoffman I remember last year you mentioned something about a +AO December being a bad thing once...but I can't remember whether you were talking specifically for whatever winter you were referring to, or in general)

Just ran through the numbers:

Since 1950, there have been 33 winters with a positive AO in December. 25 of those winters featured 1 inch or less of snow in DCA and among those, 15 were complete shutouts. The average snowfall in +AO winters is just 1.2" while only 3 have featured 6" or more in December.

However, the rest of those seasons averaged 12.7" which is in line with the long term average of 13.2". 12 of those winters featured a 6"+ snowfall at another point in the winter including 6 of the shutout winters.

Conclusion? If the AO is positive then odds are very high December is doomed in DC. However, there is definitely still hope especially if the AO eventually turns negative, which was the case in most of above average winters. 

[Maestrobjwa]

7 minutes ago, Winter Wizard said:

Just ran through the numbers:

Since 1950, there have been 33 winters with a positive AO in December. 25 of those winters featured 1 inch or less of snow in DCA and among those, 15 were complete shutouts. The average snowfall in +AO winters is just 1.2" while only 3 have featured 6" or more in December.

However, the rest of those seasons averaged 12.7" which is in line with the long term average of 13.2". 12 of those winters featured a 6"+ snowfall at another point in the winter including 6 of the shutout winters.

Conclusion? If the AO is positive then odds are very high December is doomed in DC. However, there is definitely still hope especially if the AO eventually turns negative, which was the case in most of above average winters. 

So those numbers were just for the month of December during those years? Now I was asking about whether a December +AO had negative implications for the rest of those winters (i.e JFM) (were your numbers just for December snowfall totals or the whole winter?)

[Winter Wizard]

5 minutes ago, Maestrobjwa said:

So those numbers were just for the month of December during those years? Now I was asking about whether a December +AO had negative implications for the rest of those winters (i.e JFM) (were your numbers just for December snowfall totals or the whole winter?)

Yes, I was talking strictly December snowfall vs. rest of the season. Rest of season snowfall is about average with +AO Decembers. 

[psuhoffman]

3 hours ago, Maestrobjwa said:

Did someone say a +AO in December was a bad sign for the winter as a whole? @psuhoffman I remember last year you mentioned something about a +AO December being a bad thing once...but I can't remember whether you were talking specifically for whatever winter you were referring to, or in general)

Depends. A slightly pos AO doesn’t mean much for the rest of winter. A very +AO in November and December tends to favor a +AO the rest of winter. Overall a +AO is just a bad thing in any winter month. We only have 3 of them and when a strongly + AO sets in Dec to Feb  we often can kiss a long stretch of our limited window for snow goodbye.

 

But overall I am more on the chaos side of things.  There are some very rare winters like 96 2003 and 2010 where so much was right that we were destined for greatness. And there are some really awful years like 2008 and 2012 where so much was wrong that even a decent year was unlikely. But like 80% of our winters I think luck can push us one way or the other between a typical crappy 5-10” year and a good 20” year in the DC/Balt region.  All you’re talking is 1-2 storms between those opposite fates. We remember 2 years ago as bad but all around us had above normal snow. We just missed 4/5 of the good storms to effect the general region that year.  And in different ways. Bad luck. 2014 and 2015 seemed like we got lucky every opportunity. The pattern wasn’t even that good most of the time. I suspect this winter will be in the variable pattern where luck on a few threats will determine our fate type. 

[CAPE]

If the winter months feature a legit +AO, there better be a well placed ERO ridge on steroids to get any significant cold air delivery down here. We have seen that work recently, although we got lucky with the results at least one of those years. Even so, the mean pattern that sets up in that scenario mostly supports nickel and dime snow events with big ticket warm cutters.

[poolz1]

I dont see anything to complain about.  EPS has the MJO going into the COD or low amplitude warm phases and the EPS extended H5 is great, imo.  If this is our background state....we in good shape.  Maybe a little wishful thinking but steady as she goes...Snow chances that can be taken seriously will soon be in forecast range.  This year flew by...good grief.  Seem like the older you.....

[BTRWx's Thanks Giving]

1 hour ago, Winter Wizard said:

Yes, I was talking strictly December snowfall vs. rest of the season. Rest of season snowfall is about average with +AO Decembers. 

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? 

[frd]

1 hour ago, poolz1 said:

I dont see anything to complain about.  EPS has the MJO going into the COD or low amplitude warm phases and the EPS extended H5 is great, imo.  If this is our background state....we in good shape.  Maybe a little wishful thinking but steady as she goes...Snow chances that can be taken seriously will soon be in forecast range.  This year flew by...good grief.  Seem like the older you.....

Not bad..... as you said, steady as she goes.  

 

[frd]

At least we are not looking at a 2018-ish playbook.

 

[dmillz25]

 

[Maestrobjwa]

5 hours ago, psuhoffman said:

We remember 2 years ago as bad but all around us had above normal snow. We just missed 4/5 of the good storms to effect the general region that year.

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?

[WEATHER53]

A confirmation analog we like is very late Oct coastal crawlers. Few exceptions but usually not a good sign for winter. Look clear this year 

[showmethesnow]

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.

[showmethesnow]

GEFS is luke warm at best to the possibility of a coastal roughly day 14-15 that is suggested on the EPS. About the only clue that suggests the possibility is that we are seeing confluence setting up in the south during this time period. Problem is, is that we are seeing a fairly deep drop of the trop pv into central Canada which is suppressing the flow through the east. We see that relax some in future runs and then I would not be surprised if the GEFS started picking up on the possibilities. That said one member does show 6-10 through all of central MD from what looks to be a southern system pulling northward.