Rising confidence in favorable period for snow Dec 15 - Jan 1

[earthlight]

To the quickly accumulating amount of people panicking about the pattern evolution over the next few weeks, I have three words:

 

Stay the course. 

 

The pattern and evolution of global circulations remains generally on track with forecasts from earlier this month, especially our winter forecast which was released back at the beginning of November. The progression of Wave 1/2 stratospheric warming events and their position remains on schedule (despite a generally failed and hyped first wave), and the response in both the Pacific and Atlantic remains excellent. 

 

Beginning two weeks or so ago, a large Pacific ridge soared northward into Alaska and British Columbia as a result of an extra-tropical cyclone. But the extra-tropical cyclone wasn't the entire story...the pattern was amplified as it stood anyway. And so the ridge moving northward simply dislodged arctic cold to the south (go check your thermometers this morning). The AO and especially EPO took a nose dive, as did our mid level height and temperature departures. 

 

 

Monthly SSTA's show a continued "textbook" +PDO pattern and Atlantic pre-NAO loading pattern setup. Those of you panicking about the NAO not going and staying negative over the past few days will have to take a step back from your computers --- because it probably won't do so for a few more weeks. The SSTA pattern we observed in October has a very correlation to -NAO winters, but almost all of them didn't develop fully until mid December. 

 

Further aiding in our progression is the stratosphere. A much hyped Wave 1 event occurred but was not strong enough to disrupt or split the vortex. The Euro shows this vortex holding strong for the greater part of the next seven days. But then, as if directly on cue, a huge development occurs. The Euro is now splitting the PV at multiple levels...most notably 70mb and 10mb...as a result of stratospheric warming in Eurasia/Siberia.

 

This is a huge development as it means that heat flux from the above normal snow there has done its job. The stratosphere is responding.

 

 

 

While I can't speak for the exact timing and accuracy of individual models, recent medium range forecasts play right into the forecast from several weeks ago. Much above normal snow cover over Siberia and the heat flux results in a step-down progression of a stratospheric warming event, eventually leading to a disrupted PV and changing pattern by Mid December. Historically, these events have led to a -AO and -NAO response in 2-4 weeks lead time. 

 

Although these stratospheric events are unpredictable, here's what I anticipate over the next several weeks:

 

A moderating but changeable pattern compared to the current one will take over through the 1st week of December. Pacific energy and waves will continue to crash into the West Coast, but the slower response from the Atlantic side will make it difficult to achieve any winter weather prospects in our area. Still, the anomalous cold will remain impressive in shots behind storm systems. The pattern changes wont' become extremely noticeable until the middle of December, when the response to a changing and disrupted PV will be felt. 

 

With the MJO favorability increasing in-time with the effects from the changing stratosphere and increased high latitude blocking, early signals are for heightened potential of winter weather events in the Northeast US from December 15th onward, with indications suggestive of the active period continuing through at least January 1st.

 

While variance can be stressed and understood, it must be known that this isn't a forecast for significant snow -- it is impossible to tell the details of individualized events at this range. But the potential for snow -- and an active period of potential -- certainly seems to be heightened during this period as it stands right now.

 

I'll update this thread as we draw closer...

[snywx]

Excellent write up as always John... I just find it funny how you mention ppl are panicking yet I look outside the window and heavy snow is falling..

[earthlight]

Excellent write up as always John... I just find it funny how you mention ppl are panicking yet I look outside the window and heavy snow is falling..

 

You should see some of the deleted posts about the upcoming warmth on the ensembles. 

[snywx]

You should see some of the deleted posts about the upcoming warmth on the ensembles. 

 

We just have to remind ourselves its still Nov. We tend to forget from time to time especially the spoiled ones.

[REDMK6GLI]

Even the EURO is having a hard time nailing down a pattern on its ensembles past 10-12 days. pattern changes will come mid-late december everyone who is panicking or in layman's terms when our snow chances all the way down to the coast increase drastically. Great write up as always john

[SnoSki14]

So what happens after Jan 1st, do we warm up again or is that too far out to know for certain.

I'll trust what Earthlight has to say since he's never steered us wrong and other METs seem pretty confident things change by mid December so it's a waiting game. I'll sacrifice half of December to avoid a grinch storm.

[REDMK6GLI]

So what happens after Jan 1st, do we warm up again or is that too far out to know for certain.

I'll trust what Earthlight has to say since he's never steered us wrong and other METs seem pretty confident things change by mid December so it's a waiting game. I'll sacrifice half of December to avoid a grinch storm.

Any pattern will relax but i highly doubt when it does we lose the pattern. When we establish that block over the top it will be very difficult to dislodge it. We may moderate temporarily but like last year no sustained warmth. Thats my opinion

[IrishRob17]

You should see some of the deleted posts about the upcoming warmth on the ensembles. 

 

I can only imagine, I don't envy the mods job these days.  Nice write up.

[Eduardo]

Excellent write-up, John.  For me, the only potential fly in the ointment is the MJO....it needs to either progress towards Phase 7/8 or diminish entirely.  Assuming it doesn't cooperate, do you think other teleconnections would suffice to overcome a hostile MJO during this forecast period?

[MJO812]

I like the looks of the pattern moving into December.

So what happens after Jan 1st, do we warm up again or is that too far out to know for certain.

I'll trust what Earthlight has to say since he's never steered us wrong and other METs seem pretty confident things change by mid December so it's a waiting game. I'll sacrifice half of December to avoid a grinch storm.

 

We didn't see our 1st snowstorm until December 26,2010. We know how that winter played out.

[PB GFI]

Next weeks warm up muted on the 12z Euro -  2 of the next 10 are above  normal . 1st and the 3rd . The rest appear to be below .

 

The Trough is stuck off the WEST COAST . Argues for a pos PNA and a trough in the east .

Dec may not open above normal

[SnoSki14]

I did notice how much the models scaled back on the torch to begin December including the gfs. It even has a nice cold shot for the 2nd. The changes in guidance regarding the AO and PNA has been huge these last few days.

It's like the reverse of when the models show cold in the LR and it ends up much warmer during past mild winters

[PB GFI]

That's the classic El Nino/+PDO Aleutian Low that should eventually pump the PNA/EPO ridge.

We are seeing the strongest +PDO signature from the fall into early winter in a long time.

 

PDO.gif

If Nov was warm and we saw that we would all be saying finally . That is not a bad look . Much different than  the last 5- 6 day Ensemble runs for the opening week . Lets hope it has legs

[PB GFI]

Yeah, that +PDO signature is so strong with all the warm water off the West Coast that the

the -EPO/+PNA  ridge pattern will return again after the brief MJO 3-5 push next week. You 

can see how persistent the pattern has been in October and November.

 

500.gif

 

sst.gif

Do you have the Euro MJO ?

[Weathergun]

Do you have the Euro MJO ?

The Euro MJO forecasts. Very amplified signal possibly progressing into phases 7/81 later in the month:

 

 

[PB GFI]

Yeah, I believe this was updated with the 0Z runs. It's a quick passage through 4-6 next week.

If we make it to 8-1 the second week of December, then that would just reinforce the Aleutian

Low pattern pumping the EPO/PNA ridge.

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml#for

The less amplified look collapsing into the COD after 4 then reemerging into 7 would really be a nice solution .

[PB GFI]

The Euro MJO forecasts. Very amplified signal possibly progressing into phases 7/81 later in the month:

 

 

4- 5- 6 I will pass thanks . Ensembles on there way out now . Would like to see if there`s any match off the WC thru day 10 .

[REDMK6GLI]

The less amplified look collapsing into the COD after 4 then reemerging into 7 would really be a nice solution .

Phases 7/8/1 would all be very nice but phase 7 would be most beneficial. Really fits the el nino persona where december many times is a setup for january/february

[donsutherland1]

Really outstanding discussion, John. I fully agree with how you see things evolving.

[tim]

..earthlight and don sutherland both saying game on..that puts my LR fears to bed.

[Weathergun]

4- 5- 6 I will pass thanks . Ensembles on there way out now . Would like to see if there`s any match off the WC thru day 10 .

The GEFS is already way ahead of Euro ENS in returning the Aleutian Low and +PNA pattern in the second week of December.  I think Euro ENS will catch up eventually. The stratospheric warming from Siberan snow cover heat flux and Central Pacific-based El Nino trends, also point more high-latitude blocking developing later in December and January.:

 

[PB GFI]

The GEFS is already way ahead of Euro ENS in returning the Aleutian Low and +PNA pattern in the second week of December.  I think Euro ENS will catch up eventually. The stratospheric warming from Siberan snow cover heat flux and Central Pacific El Nino trends, also point more high-latitude blocking developing later in December and January.:

 

Agree Look at the 0z Euro from the 25th  at 216 vs todays 180 . The trough is deeper in the GOA  so it pumps the ridge  like the GFS and you can see how the trough is getting deeper through the lakes. So the week long torch looks like it will cool as we get closer .

 

At least that's the OP looks to me as well .

[Yanksfan]

After looking at the water vapor loop last night with that Elnino induced subtropical jet coming out of the gulf, I will be very surprised we don't see a HECS this winter once our -NAO returns. Not to mention a +PNA and a lurking PV. Exciting times ahead!

[PB GFI]

The base state is +PDO so once past 4-6 we revert back to -EPO/+PDO either in COD or 8-1.

I Just went into the DEC thread and checked what I posted on the Monday. I  thought by the10th it would be game on again  .

Nice signal S of the Aleutians day 12 - 15  on the ensembles to really re fire that ridge .

 

The Euro is so much better in the Pacific in the LR with its GOA placements and just terrible on the EC . I like how that combines with what John thinks around  mid month  .  Something to look forward to .

[snywx]

..earthlight and don sutherland both saying game on..that puts my LR fears to bed.

[SnoSki14]

Of course there's no guarantee about anything especially snows even if the pattern turns favorable. Last March and even late February were good examples of that.

However a better pattern makes it more likely we get something with blocking greatly increasing the odds. With blocking probably coming in January moreso than December it's not out of the question our first solid storm comes in January rather than December.

[IntenseBlizzard2014]

Of course there's no guarantee about anything especially snows even if the pattern turns favorable. Last March and even late February were good examples of that.

However a better pattern makes it more likely we get something with blocking greatly increasing the odds. With blocking probably coming in January moreso than December it's not out of the question our first solid storm comes in January rather than December.

If we were to have today's storm during a moderate blocking time period, then I guarantee you that it would have been a storm to remember.

[Redmorninglight]

Of course there's no guarantee about anything especially snows even if the pattern turns favorable. Last March and even late February were good examples of that.

However a better pattern makes it more likely we get something with blocking greatly increasing the odds. With blocking probably coming in January moreso than December it's not out of the question our first solid storm comes in January rather than December.

What was wrong with March? Lol.

All jokes aside, thanks guys for your contributions. We are all looking forward to a pattern that delivers the goods.

[Chaser25973]

Threads and discussions like this are the reasons why I come to this forum... wow! Brilliant discussion!

[SnoSki14]

What was wrong with March? Lol.

All jokes aside, thanks guys for your contributions. We are all looking forward to a pattern that delivers the goods.

Oh yes extreme S NJ the snow capital of the Northeast lol.