December Med/Long Range Disco

[Webberweather53]

With the arrival of the insane Pacific Jet this week, it will kick off a parade of southern stream lows--one after another. Models, especially ensemble means, will average this out in the day 10-15 period and make it look like some "3-wave configuration" etc. But in reality, a classic PNA, split flow will develop and models will screw-up this separation (especially the GFS). So, expect continued correcting from a smoother, longer wavelength to a shorter wavelength/split stream from the day 10-15 means to day 6-10 means.

There is NO torch coming and eventually these monster southern lows will pay off...

 

Well said.. I posted this on SE US wx forum in response to your comment...

 

"I concur. Thanks in part to the MJO milling around in the Pacific & it's coincident shift in the mean upward motion signal/convection increasing upper level divergence that is effectively accelerating the Pacific jet stream to its north, we're seeing quite an extension of the Pacific Jet (to equalize this increase in acceleration)... W/ an already amped subtropical jet courtesy of CCKW passage & our low frequency ENSO & PDO base state this = a parade of undercutting w/ the southern stream & @ the very least... I.e. generally unsettled weather in the southern tier that's all too commonplace in a N American El Nino winter...

 

+ENSO MJO Dec 500mb composites for phases 7-1 (Central Pacific-Western Hemisphere)"

 

[HM]

Thanks Eric, looks good. The Pacific Jet is mouth-dropping right now! That's got to be one of the strongest!

[mitchnick]

Thanks Eric, looks good. The Pacific Jet is mouth-dropping right now! That's got to be one of the strongest!

HM, do you think that warm water off the west coast is contributing to the pacjet or is it all Nino? I say yes, but that means nothing. Lol

[Deck Pic]

Let's think about this logically. Think about how close a few of these storms have been to being decent events. The background state from the Pacific will not change so we shouldn't expect a big SE ridge pattern in the long-term means any time soon. Therefore, each week, it can only grow colder as we had towards climatological minimum. Eventually, these lows will become legitimate snow threats...and that's just with the current pattern and background state. I didn't even touch the potential for a significant AO/NAO decrease mid-winter.

 

If we were going to get a classic se/bermuda ridge it would probably be happening now.... I doubt we see one all winter....Poor Miami...they have no idea what's coming, and how it will keep reloading all winter

[HM]

HM, do you think that warm water off the west coast is contributing to the pacjet or is it all Nino? I say yes, but that means nothing. Lol

What we have is an extremely large gradient. While the continents are cold with snow cover and the NW Pacific SST are below normal, we have a vast area of warmer SST just to the south. Finally, the Hadley Cell is being accelerated by El Nino and the associated warm areas throughout the subtropical N Pac. The convection here is speeding up the STJ. So all of these forces are coming together to make a rather impressive jet.

[HM]

If we were going to get a classic se/bermuda ridge it would probably be happening now.... I doubt we see one all winter....Poor Miami...they have no idea what's coming, and how it will keep reloading all winter

I haven't seen a southern stream modeled like this in a while. I am pretty impressed with that end of things. And yes, I know everything currently is being enhanced by the MJO etc. but it's still nice to see again. That's all you can ask for when you live in the Mid Atlantic...now we've got to get lucky.

[HM]

What we have is an extremely large gradient. While the continents are cold with snow cover and the NW Pacific SST are below normal, we have a vast area of warmer SST just to the south. Finally, the Hadley Cell is being accelerated by El Nino and the associated warm areas throughout the subtropical N Pac. The convection here is speeding up the STJ. So all of these forces are coming together to make a rather impressive jet.

I forgot the mention that the typhoon, in particular, this week is really ramping up the wind level too. Of course, the MJO-ENSO component sort of includes that end to things...

http://www.cpc.ncep.noaa.gov/products/intraseasonal/irtempanim_2.gif

[Webberweather53]

Thanks Eric, looks good. The Pacific Jet is mouth-dropping right now! That's got to be one of the strongest!

 

Thanks! You're telling me.. You know the +PDO is strong when you can just throw up the strongest Sep-Oct warm PDO years (minus cold ENSO) in the record & the pattern follows it nearly verbatim. I usually notice when the PDO in particular is abnormally strong like this it tends to overwhelm & dominate the entire pattern. Luckily we don't have the kind of cold PDO we've been accustomed to the last several years or else we'd be hitting the snooze button right now...

[H2O]

HM posting=

 

[Webberweather53]

Thanks! You're telling me.. You know the +PDO is strong when you can just throw up the strongest Sep-Oct warm PDO years (minus cold ENSO) in the record & the pattern follows it nearly verbatim. I usually notice when the PDO in particular is abnormally strong like this it tends to overwhelm & dominate the entire pattern. Luckily we don't have the kind of cold PDO we've been accustomed to the last several years or else we'd be hitting the snooze button right now...

 

I guess so much for "comprehensive" analoging, lol. Relatively speaking, we're being handed this one on a silver platter...

[eurojosh]

Good visualization of the Pac jet now by pulling up the 500 hPa wind map here: http://earth.nullschool.net/#current/wind/isobaric/500hPa/orthographic=-126.13,34.20,347

 

(link is time-sensitive).

[WxUSAF]

Ensembles less impressive with the pattern change today unfortunately.  Haven't looked closely to see if it's just a function of more spread amongst the members, but the +PNA/-EPO combo looks generally weaker and the high heights in Canada don't retreat quite as far north.  Last night's Euro ensembles and today's 12z GEFS both sort of show this.  

[Bob Chill]

Ensembles less impressive with the pattern change today unfortunately. Haven't looked closely to see if it's just a function of more spread amongst the members, but the +PNA/-EPO combo looks generally weaker and the high heights in Canada don't retreat quite as far north. Last night's Euro ensembles and today's 12z GEFS both sort of show this.

Looks like a typical push back in time is starting to show. GEFS has trended towards more members digging storms down the west coast instead of coming under a pna ridge. And it shows on the means. With more members showing that kind of evolution, the downstream response is less troughing on the means in the east. Euro eased up last night a bit as well.

 

Still decent support for a serviceable pattern imo:

 

[usedtobe]

Ensembles less impressive with the pattern change today unfortunately.  Haven't looked closely to see if it's just a function of more spread amongst the members, but the +PNA/-EPO combo looks generally weaker and the high heights in Canada don't retreat quite as far north.  Last night's Euro ensembles and today's 12z GEFS both sort of show this.

Yep, not looking as quick with a distinct pattern change.  We'll see if it's just a blip or if any change is going to take a little longer. 

[BTRWx]

Since this is a long range thread and I like to think outside the box often, has anyone ever considered compiling climatological statistics from every operational model run from a particular model between given time frames? Like instead of running multiple model runs for the actual forecast ensemble, can something similar be done for past climatological records for time periods covering good analogs?

[WxUSAF]

Yep, not looking as quick with a distinct pattern change.  We'll see if it's just a blip or if any change is going to take a little longer. 

On the other hand, we could just hug the Canadian ensembles.

 

[usedtobe]

On the other hand, we could just hug the Canadian ensembles.

 

gem-ens_z500a_nhem_65.png

I think I'm in love.  Too bad it's thee worst of the three ens forecasting systems.  I was looking forward to my Thursday outlook, now I'm hoping the Canadian is right so I have something interesting to write.

[WxUSAF]

I think I'm in love.  Too bad it's thee worst of the three ens forecasting systems.  I was looking forward to my Thursday outlook, now I'm hoping the Canadian is right so I have something interesting to write.

We'll see what the Euro ensembles show, but I think the weaker look on the GEFS is due in large part to spread between the strength and placement of some of these strong s/w's/closed lows coming off the Pacific as Bob showed in his image.  In either case, I think the pattern will turn more favorable, but still an open question on whether it goes from hostile to snow (like now and the next week) to just non-hostile or to outright favorable and SECSy like the Canadian ensembles (and yesterday's GEFS and Euro ensembles) showed.  

[usedtobe]

Since this is a long range thread and I like to think outside the box often, has anyone ever considered compiling climatological statistics from every operational model run from a particular model between given time frames? Like instead of running multiple model runs for the actual forecast ensemble, can something similar be done for past climatological records for time periods covering good analogs?

 

Since this is a long range thread and I like to think outside the box often, has anyone ever considered compiling climatological statistics from every operational model run from a particular model between given time frames? Like instead of running multiple model runs for the actual forecast ensemble, can something similar be done for past climatological records for time periods covering good analogs?

That has been done for temperatures and precipitation probabilities ( The difficulty in doing that is that you cannot make any changes to the ensemble forecast system ( If you do you have to redo the climo.  Still, the method has real possibilities and the guys working on it are really smart.  

 

I've tried twice to link to the site that shows the reanalysis forecasts but for some reason AMWX won't let me link to it.  If you are interested.   Google ESRL reanalysis project, that should take you to the site.

[Ian]

Euro weeklies will save us

[Bob Chill]

We'll see what the Euro ensembles show, but I think the weaker look on the GEFS is due in large part to spread between the strength and placement of some of these strong s/w's/closed lows coming off the Pacific as Bob showed in his image.  In either case, I think the pattern will turn more favorable, but still an open question on whether it goes from hostile to snow (like now and the next week) to just non-hostile or to outright favorable and SECSy like the Canadian ensembles (and yesterday's GEFS and Euro ensembles) showed.  

 

Euro looks ok but I'll hug the GGEM instead..lol

 

 

 

It's similar to the GEFS in evolution. A parade of shortwaves entering the west and tracking through the southern 1/3rd of the country. There are 3 distinct shortwaves on this run and they are equally spaced. The 3rd one shows the western ridge building behind it and cutting off the npac shortwaves. Too muddy to draw any conclusions about when the "real" favorable pattern sets up. At least we'll have what appears to be 3 storms traversing the country from d8-15. Not really a good look for cold hp's until the end of the run IMHO. 

[stormtracker]

Euro weeklies will save us

They always pan out for us.

[WxUSAF]

^nice Bob.  That looks better than the 0z ensembles from what I recall.  There certainly is a storm signal for late next week on the ensembles, but cold air is lacking as you mention.  

[Bob Chill]

^nice Bob.  That looks better than the 0z ensembles from what I recall.  There certainly is a storm signal for late next week on the ensembles, but cold air is lacking as you mention.  

 

The last 3-4 ensemble runs have ended up near the same at the end of the run but getting there is changing. Timing appears to have moved just a little bit forward in time. Wavelengths stay pretty short for what looks to be the next 12 days or so. That's going to cause some jumpy op and ensemble runs in the med-long ranges. What the models seem to agree is that we are headed for longer wavelengths and better ridge/trough positions. But only hints of good blocking showing up for now. 

 

Total wag- the next storm traversing the country stands little chance due to lack of cold air. One after that will have some snow for folks who end up on the NW side. The 3rd one is going to give us a white Christmas. 

[BTRWx]

That has been done for temperatures and precipitation probabilities ( The difficulty in doing that is that you cannot make any changes to the ensemble forecast system ( If you do you have to redo the climo.  Still, the method has real possibilities and the guys working on it are really smart.  

 

I've tried twice to link to the site that shows the reanalysis forecasts but for some reason AMWX won't let me link to it.  If you are interested.   Google ESRL reanalysis project, that should take you to the site.

Thanks for commenting. Yes, I'm well aware of the ESRL products and am anxious to see them continue to expand.

[usedtobe]

The last 3-4 ensemble runs have ended up near the same at the end of the run but getting there is changing. Timing appears to have moved just a little bit forward in time. Wavelengths stay pretty short for what looks to be the next 12 days or so. That's going to cause some jumpy op and ensemble runs in the med-long ranges. What the models seem to agree is that we are headed for longer wavelengths and better ridge/trough positions. But only hints of good blocking showing up for now. 

 

Total wag- the next storm traversing the country stands little chance due to lack of cold air. One after that will have some snow for folks who end up on the NW side. The 3rd one is going to give us a white Christmas. 

I like that look better than the 00Z one and hope it stays for 3 more days.  That's back to an above normal pattern for getting snow if it were to pan out.

[Amped]

Definitely a good pattern for getting southern stream systems, cold air will be marginal however but at least it has some potential.

[Bob Chill]

They always pan out for us.

 

They look pretty much the same as the ensemble mean I posted a little while ago for 2 weeks straight. The only differences is the AO and EPO go further negative during the period. NAO looks to start cooperating sometime during or after the first week of Jan. Almost a classic nino snow pattern for us but not perfect with the nao...yet....

[Ian]

They look pretty much the same as the ensemble mean I posted a little while ago for 2 weeks straight. The only differences is the AO and EPO go further negative during the period. NAO looks to start cooperating sometime during or after the first week of Jan. Almost a classic nino snow pattern for us but not perfect with the nao...yet....

January will bring all the HECS to the yard.

[BullCityWx]

January will bring all the HECS to the yard.

 

You better be right.