Winter 2019-20 Medium/Long Range Discussion

[RCNYILWX]

00z EPS (ECMWF ensemble) has continued theme of last few days of going to a very cold pattern look out in the day 10-15. MJO is at a very high amplitude phase 4 crossing into 5, warm phases for the winter explaining the very pronounced east/southeast ridge currently.

According to information posted on other subs by Don S, this progression has historically supported the MJO wave keeping enough amplitude to progress into the colder phases. Assuming this holds, the idea of a sustained colder pattern unfolding later in January and beyond holds merit. The GEFS has also basically gone over to the EPS idea out in the extended.

I still think our best chance for a more significant spread the wealth type of event would be prior to the pattern going in the direction of the EPS, if it's on the right track. Thereafter, the exact position and orientation of mean western and Alaskan ridging and downstream trough over will determine whether we go to a very cold and dry clipper type pattern (ex. Feb 2015 after GHD II) or a more active but just as cold pattern (ex. January-February 2014).

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[michsnowfreak]

4 hours ago, RCNYILWX said:

00z EPS (ECMWF ensemble) has continued theme of last few days of going to a very cold pattern look out in the day 10-15. MJO is at a very high amplitude phase 4 crossing into 5, warm phases for the winter explaining the very pronounced east/southeast ridge currently.

According to information posted on other subs by Don S, this progression has historically supported the MJO wave keeping enough amplitude to progress into the colder phases. Assuming this holds, the idea of a sustained colder pattern unfolding later in January and beyond holds merit. The GEFS has also basically gone over to the EPS idea out in the extended.

I still think our best chance for a more significant spread the wealth type of event would be prior to the pattern going in the direction of the EPS, if it's on the right track. Thereafter, the exact position and orientation of mean western and Alaskan ridging and downstream trough over will determine whether we go to a very cold and dry clipper type pattern (ex. Feb 2015 after GHD II) or a more active but just as cold pattern (ex. January-February 2014).

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It goes without saying that cold & active would be the preference, however, even cold, dry and clippery is a massive improvement over what we've had in December and January. After a nice bout of sustained Winter in November, it's been nothing but fleeting cold shots and brief periods of snow which quickly melted. So now that the light is at the end of the tunnel, I am counting down the days lol.

[jbcmh81]

3 hours ago, michsnowfreak said:

It goes without saying that cold & active would be the preference, however, even cold, dry and clippery is a massive improvement over what we've had in December and January. After a nice bout of sustained Winter in November, it's been nothing but fleeting cold shots and brief periods of snow which quickly melted. So now that the light is at the end of the tunnel, I am counting down the days lol.

For Michigan and the Upper Lakes/Midwest, it looks fine, but the OV still looks like trash in the extended.

[michsnowfreak]

31 minutes ago, jbcmh81 said:

For Michigan and the Upper Lakes/Midwest, it looks fine, but the OV still looks like trash in the extended.

 Not so sure about that, it appears the cold will be widespread.

[mimillman]

The euro does not look good

[buckeye]

if this is where we are 10 days from now....I'm not seeing a pattern change.   Same old craptastic, wavy, fast moving, cold air-lacking, hoping-for-a ---well- timed wobble to accidentally fall into some snow....    pattern.

[A-L-E-K]

1 hour ago, buckeye said:

if this is where we are 10 days from now....I'm not seeing a pattern change.   Same old craptastic, wavy, fast moving, cold air-lacking, hoping-for-a ---well- timed wobble to accidentally fall into some snow....    pattern.

 

this guy gets it

[A-L-E-K]

about as ugly as it gets

[DAFF]

On ‎1‎/‎9‎/‎2020 at 10:28 AM, DaveNay said:

Right now the Euro and the GFS are in strong disagreement over temps on Wed.

 

 

I'd say the Euro is one step closer, in getting out of the ALEK doghouse..

[Cary67]

1 hour ago, DAFF said:

I'd say the Euro is one step closer, in getting out of the ALEK doghouse..

Better with temps not so much overamped storms 

[OHweather]

I'm just here to spread false hope of a pattern change that'll never come (though we're already setting things in motion this week with a brief -EPO that does dump a good amount of cold into Canada and the eastern half of the U.S.)...

I don't totally hate the odds of a storm/event around the 23rd-25th across a good portion of the sub forum, with fairly strong ensemble support for a decent shortwave to eject out of the southwest.  With some bootleg blocking across Hudson Bay, lower heights over the southeast, and surface ridging over the top ahead of this feature, I think there's a good shot it's wintry.  850mb temperatures are near normal (after being cold for a few days prior) and are workable with the ensemble mean 0C line south of the Ohio River ahead of this wave.  If it deepens too quickly it would still cut and change the Ohio Valley to rain (or perhaps simply give them mostly/all rain), but places like Iowa/Wisconsin/Michigan, Chicago, Detroit, and maybe even Indy/Toledo/Cleveland would probably see a half decent amount of snow if an organized system can eject in this time-frame.  Places like Pittsburgh and Columbus/Dayton/Cincinnati still can snow but would likely need to root for a more strung out system, as the "blocking" to the north isn't strong enough to stop a stronger system from cutting too early for them.

As for the "pattern change", both the tropics and extra-tropics don't really say it should be here yet...I think the ensembles several days ago (and hence those of us rooting for a pattern change) rushed the change a bit, but things suggest it's probably still 10-15 days away from really being "there"...

The MJO is at an extremely strong amplitude in phase 5/by tomorrow 6...these are not cold phases, though do usually end up being cold within 2-3 weeks of their occurrence.

Here are lagged composites of what happens after a phase 6 MJO at an amplitude of 1 or greater...although the MJO accounts for something like 25% of the sub-seasonal variability observed over a large sample, this is a very strong MJO and will influence the pattern.  Each lag is 5 days.

This does not suggest a more legitimate pattern change that dumps cold into the CONUS for another 10-15 days (though does suggest slightly faster high-latitude changes, which we are seeing).  Phase 7, which we'll reach in 5-7 days, leads to cold by lag 1 which is 5-10 days (and supports the timeline from a current phase 6) and is typically cold thereafter for quite a while.  Phase 8 is cold immediately and for quite a while.  Here is a link to these composites for anyone interested: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/LaggedComposites/

Basically, tropical forcing says we should not yet be cold and probably shouldn't be for another 10-15 days, so it's probably not that surprising that the mid-range guidance has delayed a persistent cold pattern but still shows one developing past day 10.  This should start moving up in time as the MJO keeps propagating.

Global angular momentum (GWO, AAM, GLAAM, whatever your acronym) will rise soon, but it hasn't yet.  A low AAM is more typical of a La Nina, supports a strong stratospheric polar vortex/+AO, and trough over the western U.S.  We have been gradually climbing towards a more persistently positive AAM since the middle of fall, but it's been a slow climb, and I think the AAM slipping negative for most of December (after a couple of positive attempts in November) contributed to the strong stratospheric PV and +AO we are dealing with right now.  It spiked at the end of December, but the tropospheric pattern was horrible with a PV over Alaska and the stratospheric PV was too strong for that spike to significantly disrupt it.

The strong MJO over the next two weeks, along with a fairly strong East Asian Mountain Torque (high pressure east of the mountains) will add a lot of momentum over the next two weeks, and we will see the strongest positive AAM spike of the fall/winter by far.  Here is the EPS sea level pressure anomaly forecast for hour 264 showing this strong mountain torque, along with the CFS AAM forecasts for the next month:

This added momentum will help fuel an already active sub-tropical jet, will support some jabs to the stratospheric PV, and the MJO moving through the western Pacific as a +East Asian MT occurs will support significant amplification in the EPO/PNA domains.

Basically, I understand it's frustrating waiting a bit longer after over a month of really unfavorable conditions for snow for most of the sub and that it may seem like the models are perpetually pushing cold back, but there are reasons we didn't flip as quickly as the models suggested..basically the drivers didn't support it yet...and there are numerous reasons to expect it to still change soon.  The combination of factors we will see the rest of this month is unlike anything we've seen so far this fall/winter and I would be flabbergasted if it didn't result in a shakeup in the pattern.  I think the trick will be figuring out if we go back to warm in mid-late February, or if it's a more prolonged change that carries us through the rest of winter.  I don't know the answer to that yet.

After the potential system around the 23rd-25th (that favors the northwestern 2/3rds of the sub) there may be a similar opportunity a few days later.  Thereafter individual threats become murkier, but it should stay active and I think we see the EPO drop more than the EPS suggests in the 10-15, which will eventually push the baroclinic zone far enough south to favor the Ohio Valley over the Great Lakes. 

 

[Hoosier]

Fantastic post OHweather.  Thanks. 

[michsnowfreak]

13 minutes ago, Hoosier said:

Fantastic post OHweather.  Thanks. 

I agree!!! Thanks!

[RCNYILWX]

I'm just here to spread false hope of a pattern change that'll never come (though we're already setting things in motion this week with a brief -EPO that does dump a good amount of cold into Canada and the eastern half of the U.S.)...
I don't totally hate the odds of a storm/event around the 23rd-25th across a good portion of the sub forum, with fairly strong ensemble support for a decent shortwave to eject out of the southwest.  With some bootleg blocking across Hudson Bay, lower heights over the southeast, and surface ridging over the top ahead of this feature, I think there's a good shot it's wintry.  850mb temperatures are near normal (after being cold for a few days prior) and are workable with the ensemble mean 0C line south of the Ohio River ahead of this wave.  If it deepens too quickly it would still cut and change the Ohio Valley to rain (or perhaps simply give them mostly/all rain), but places like Iowa/Wisconsin/Michigan, Chicago, Detroit, and maybe even Indy/Toledo/Cleveland would probably see a half decent amount of snow if an organized system can eject in this time-frame.  Places like Pittsburgh and Columbus/Dayton/Cincinnati still can snow but would likely need to root for a more strung out system, as the "blocking" to the north isn't strong enough to stop a stronger system from cutting too early for them.



As for the "pattern change", both the tropics and extra-tropics don't really say it should be here yet...I think the ensembles several days ago (and hence those of us rooting for a pattern change) rushed the change a bit, but things suggest it's probably still 10-15 days away from really being "there"...
The MJO is at an extremely strong amplitude in phase 5/by tomorrow 6...these are not cold phases, though do usually end up being cold within 2-3 weeks of their occurrence.

Here are lagged composites of what happens after a phase 6 MJO at an amplitude of 1 or greater...although the MJO accounts for something like 25% of the sub-seasonal variability observed over a large sample, this is a very strong MJO and will influence the pattern.  Each lag is 5 days.

This does not suggest a more legitimate pattern change that dumps cold into the CONUS for another 10-15 days (though does suggest slightly faster high-latitude changes, which we are seeing).  Phase 7, which we'll reach in 5-7 days, leads to cold by lag 1 which is 5-10 days (and supports the timeline from a current phase 6) and is typically cold thereafter for quite a while.  Phase 8 is cold immediately and for quite a while.  Here is a link to these composites for anyone interested: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/LaggedComposites/
Basically, tropical forcing says we should not yet be cold and probably shouldn't be for another 10-15 days, so it's probably not that surprising that the mid-range guidance has delayed a persistent cold pattern but still shows one developing past day 10.  This should start moving up in time as the MJO keeps propagating.

Global angular momentum (GWO, AAM, GLAAM, whatever your acronym) will rise soon, but it hasn't yet.  A low AAM is more typical of a La Nina, supports a strong stratospheric polar vortex/+AO, and trough over the western U.S.  We have been gradually climbing towards a more persistently positive AAM since the middle of fall, but it's been a slow climb, and I think the AAM slipping negative for most of December (after a couple of positive attempts in November) contributed to the strong stratospheric PV and +AO we are dealing with right now.  It spiked at the end of December, but the tropospheric pattern was horrible with a PV over Alaska and the stratospheric PV was too strong for that spike to significantly disrupt it.
The strong MJO over the next two weeks, along with a fairly strong East Asian Mountain Torque (high pressure east of the mountains) will add a lot of momentum over the next two weeks, and we will see the strongest positive AAM spike of the fall/winter by far.  Here is the EPS sea level pressure anomaly forecast for hour 264 showing this strong mountain torque, along with the CFS AAM forecasts for the next month:


This added momentum will help fuel an already active sub-tropical jet, will support some jabs to the stratospheric PV, and the MJO moving through the western Pacific as a +East Asian MT occurs will support significant amplification in the EPO/PNA domains.
Basically, I understand it's frustrating waiting a bit longer after over a month of really unfavorable conditions for snow for most of the sub and that it may seem like the models are perpetually pushing cold back, but there are reasons we didn't flip as quickly as the models suggested..basically the drivers didn't support it yet...and there are numerous reasons to expect it to still change soon.  The combination of factors we will see the rest of this month is unlike anything we've seen so far this fall/winter and I would be flabbergasted if it didn't result in a shakeup in the pattern.  I think the trick will be figuring out if we go back to warm in mid-late February, or if it's a more prolonged change that carries us through the rest of winter.  I don't know the answer to that yet.
After the potential system around the 23rd-25th (that favors the northwestern 2/3rds of the sub) there may be a similar opportunity a few days later.  Thereafter individual threats become murkier, but it should stay active and I think we see the EPO drop more than the EPS suggests in the 10-15, which will eventually push the baroclinic zone far enough south to favor the Ohio Valley over the Great Lakes. 
 

Great, informative post. Have learned a lot about long range forecasting from reading your posts over the years.

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[Stebo]

The big takeaway from that post to me is the MJO, at the very least with a high amplitude wave, we are going to flush out the current pattern at the very least.

[buckeye]

Concensus among the weather community....

Pattern change commences January 20th.

Day 11 of pattern change :

[Hoosier]

Using the 16 day op GFS as a counterargument

Come on, man

[buckeye]

37 minutes ago, Hoosier said:

Using the 16 day op GFS as a counterargument

Come on, man

c'mon, if it was showing the polar vortex over Cleveland it would fit nicely with the calls for the end of this garbage pattern and no one would say a thing.  The point is if anything is going to show a flip to cold....it's the long range gfs.   It was for awhile, and now those looks are becoming muted more and more.    

I've got other arguments as well.... have you seen the latest mjo?    What's the argument for the flip?

Trust me...i hope i'm eating crow a week from now... and yes, we'll definitely get a cold shot after the slop storm....but I'm just not seeing us leaving this repeated back and forth, garbage pattern.   

[A-L-E-K]

Ride the icon is a solid plan

[mimillman]

PV firmly in the eastern hemisphere. Great.

[A-L-E-K]

congrats latvia

[buckeye]

#post0120patternchange

[DaveNay]

11 minutes ago, buckeye said:

#post0120patternchange

Rain at Mackinac Island in January. Who'da thunk it?

[Snowstorms]

As per the Euro, the cold air doesn't last long and by the 22nd, we're above freezing again. This is in part due to the jet cutting overtop of the region and a lack of blocking in the Pacific. It almost resembles a -PNA in the west. And instead of a 50/50 Low off the coast of Newfoundland, there's a massive ridge at 192 hrs. There's nothing amazing about this pattern or set-up. 

Edit: By 216hrs the entire nation is flooded with warm pacific air while the cold air retreats to the Arctic. 

[buckeye]

21 minutes ago, Snowstorms said:

As per the Euro, the cold air doesn't last long and by the 22nd, we're above freezing again. This is in part due to the jet cutting overtop of the region and a lack of blocking in the Pacific. It almost resembles a -PNA in the west. And instead of a 50/50 Low off the coast of Newfoundland, there's a massive ridge at 192 hrs. There's nothing amazing about this pattern or set-up. 

Edit: By 216hrs the entire nation is flooded with warm pacific air while the cold air retreats to the Arctic. 

brutal....   

[IWXwx]

24 minutes ago, Snowstorms said:

As per the Euro, the cold air doesn't last long and by the 22nd, we're above freezing again. This is in part due to the jet cutting overtop of the region and a lack of blocking in the Pacific. It almost resembles a -PNA in the west. And instead of a 50/50 Low off the coast of Newfoundland, there's a massive ridge at 192 hrs. There's nothing amazing about this pattern or set-up. 

Edit: By 216hrs the entire nation is flooded with warm pacific air while the cold air retreats to the Arctic. 

I was considering posting something about this after perusing the Euro, but didn't want to get flack from the optimists.  Although we are approaching a "pattern change", the sensible weather past day 6 doesn't look that much different.

[buckeye]

3 minutes ago, IWXwx said:

I was considering posting something about this after perusing the Euro, but didn't want to get flack from the optimists.  Although we are approaching a "pattern change", the sensible weather past day 6 doesn't look that much different.

This is where you need to refer to THE METEROLOGICAL CYA HANDBOOK by Joe Bastardi

Chapter 2 : What to say when the cold never comes

pg 127:  "....I still nailed the pattern at 500mb!"

[WestMichigan]

1 minute ago, buckeye said:

This is where you need to refer to THE METEROLOGICAL CYA HANDBOOK by Joe Bastardi

Chapter 2 : What to say when the cold never comes

pg 127:  "....I still nailed the pattern at 500mb!"

You forgot earlier on that same page "delayed but not denied" and then if that fails pivot to your answer.

[Hoosier]

2 minutes ago, buckeye said:

This is where you need to refer to THE METEROLOGICAL CYA HANDBOOK by Joe Bastardi

Chapter 2 : What to say when the cold never comes

pg 127:  "....I still nailed the pattern at 500mb!"

That was 01-02 when he had that infamous line I think.  

[Frog Town]

6 minutes ago, Hoosier said:

That was 01-02 when he had that infamous line I think.  

I feel like he said it last year 18-19 also