Where we're at, where we're going

[phil882]

ECMWF shows a Legitamate southern stream shortwave with height falls moving east FWIW. Too bad those things tend to cut off over the SW deserts in Nina years.

Hmm I would have thought the strength of the pacific jet in La Nina's would tend to create progressive flow and keep things such as upper level features in the southwest moving along at a pretty good fashion. I guess since the subtropical jet is so weak it can't push whatever upper level feature that digs down deeper in the mid-west further east. Thus the feature tends to get cutoff from the main flow of the polar jet and since there is no momemtum progressing it further east... and it just retrogrades or stalls over the SW US.

[tacoman25]

Hey taco, can you post the link to the site for those maps?

Sure.

http://www.hprcc.unl.edu/maps/current/index.php?action=update_product&product=TDept

[Ji]

If it snows in DC Sunday...la Nina cancel

[okie333]

12Z Euro shows -NAO fading going into day 10, but the mega-high just off the eastern shore of Kamchatka looks to be moving in the right direction for a mega --AO around day 12 or 13. Also notice the low moving into the 50-50 position.

[Dr No]

If it snows in DC Sunday...la Nina cancel

Actually snow in December around here is common in a Nina before things go down the crapper.

[Yes_Probably_Maybe_No]

You could be right, especially if the pattern takes longer to switch and/or the MJO doesn't become as coherent as I think it will be. Then in that case, the NAO will continue to stay lower and the cold will continue like the beginning of the month. I just think this wave is coming and will bring a warm-up. Obviously we agree on the East, but the area we disagree is the northern Plains.

MOAR -AO/-NAO plz

[HM]

ECMWF is already signaling the end with a complete collapse of the -NAO pattern and a huge ridge building into the W-C States. I don't see us getting into a classic SE ridge/NW trough pattern again until the end of the month ...final 10 days.

[nzucker]

ECMWF is already signaling the end with a complete collapse of the -NAO pattern and a huge ridge building into the W-C States. I don't see us getting into a classic SE ridge/NW trough pattern again until the end of the month ...final 10 days.

I don't think using the Day 10 OP ECM is too great of a tool for the forecast; it does show exactly what you forecasted, but it's been flip-flopping a lot in the long range. Just two runs ago, it showed a huge arctic outbreak in the CONUS with a -NAO block. The 12z ECM ENS were colder with more of a classic +PNA, keeping negative anomalies in the Midwest, Ohio Valley, and Northeast....colder for the Midwest than some of the analog years you cited like 1975.

[NEXtreme]

What happend to the torch this week? Weren't the models showing a few days in the 60's again? Now we might be Lucky to get one day to touch 60 this week. Seems to be the theme nowadays.

[Ji]

Gfs is cold and stormy thru 384. Hm might be ending the cold pattern to quick as it really hasn't started yet

[A-L-E-X]

I don't think using the Day 10 OP ECM is too great of a tool for the forecast; it does show exactly what you forecasted, but it's been flip-flopping a lot in the long range. Just two runs ago, it showed a huge arctic outbreak in the CONUS with a -NAO block. The 12z ECM ENS were colder with more of a classic +PNA, keeping negative anomalies in the Midwest, Ohio Valley, and Northeast....colder for the Midwest than some of the analog years you cited like 1975.

The models, as always, are too quick with pattern changes.  Of course, the changes do happen-- but rarely as quickly as depicted.  Just look back to the November 20th period-- the models had been signalling that as the start of the pattern change to colder-- and they were 15 days too quick with that.

[CoastalWx]

ECMWF is already signaling the end with a complete collapse of the -NAO pattern and a huge ridge building into the W-C States. I don't see us getting into a classic SE ridge/NW trough pattern again until the end of the month ...final 10 days.

I'm not so sure it totally collapses. It does weaken significantly, perhaps it remains more neautral or slightly +?? At least through the next 2 weeks or so.

Edit: unless you meant it strays from the -3SD or so value.

[nzucker]

I'm not so sure it totally collapses. It does weaken significantly, perhaps it remains more neautral or slightly +?? At least through the next 2 weeks or so.

Edit: unless you meant it strays from the -3SD or so value.

I believe that even if the NAO collapses, we may retain cold anomalies due to a ridge amplifying over Kamchatka towards the NP, bringing cold air back into Canada and towards the CONUS.

[CoastalWx]

I believe that even if the NAO collapses, we may retain cold anomalies due to a ridge amplifying over Kamchatka towards the NP, bringing cold air back into Canada and towards the CONUS.

You could argue that if the NAO weakens...the cold may go east since a strong west based nao would probably keep the cold over western Canada. it all depends on the west coast. That would be easier to come by with a sw ridge that some models are showing.

[Nikolai]

You could argue that if the NAO weakens...the cold may go east since a strong west based nao would probably keep the cold over western Canada. it all depends on the west coast. That would be easier to come by with a sw ridge that some models are showing.

I think we stay cold and snowy through December, potentially with a few blips but by and large...

Whoever was using the MJO as a basis for us entering a warm pattern was faulty as the modeled MJO forecasts have been all over the place, btw. While it was previously supposed to go into 3/4, it's basically just dawdling in the middle and now projected to only go into 4... if that even happens. I don't think forecasters can rely on the MJO for guidance this winter as it seems stuck in the doldrums, aside from an occasional signal.

[usedtobe]

I think we stay cold and snowy through December, potentially with a few blips but by and large...

Whoever was using the MJO as a basis for us entering a warm pattern was faulty as the modeled MJO forecasts have been all over the place, btw. While it was previously supposed to go into 3/4, it's basically just dawdling in the middle and now projected to only go into 4... if that even happens. I don't think forecasters can rely on the MJO for guidance this winter as it seems stuck in the doldrums, aside from an occasional signal.

Actually, if it dawdles in phase 4, we'll probably trend towards warm if it stays in phase 4 and 5 for any length of time. Luckily for us, La nina years tend to be front loaded for cold (dec) but not necessarily for snow based on climo since 1950. That may not be enough years for stat significance.

[HM]

You know what, you guys are right. The tropical forcing is meaningless and the NAO will stay negative through March.

[HM]

I don't think using the Day 10 OP ECM is too great of a tool for the forecast; it does show exactly what you forecasted, but it's been flip-flopping a lot in the long range. Just two runs ago, it showed a huge arctic outbreak in the CONUS with a -NAO block. The 12z ECM ENS were colder with more of a classic +PNA, keeping negative anomalies in the Midwest, Ohio Valley, and Northeast....colder for the Midwest than some of the analog years you cited like 1975.

I am not sure how to respond to this. If you are suggesting this is why I am forecasting a trough along the West/East Coast and ridge in between then you are wrong. If you are just saying that the 12z run I quoted was wrong...well sure. They are always wrong. That's the beauty of medium/long range forecasting...

[HM]

I'm not so sure it totally collapses. It does weaken significantly, perhaps it remains more neautral or slightly +?? At least through the next 2 weeks or so.

Edit: unless you meant it strays from the -3SD or so value.

You're right, it may not completely collapse. That run of the ECMWF did. The point is, after this big cutoff, lower heights replace the big ridge anomaly. Collapse sounds like a good word.

This isn't a warm look for the eastern third and I am by no means forecasting that. More of a variable/seasonal look with cool anomalies near the SE perhaps.

[nzucker]

You know what, you guys are right. The tropical forcing is meaningless and the NAO will stay negative through March.

I think your use of tropical forcing for winter forecasts has been amazing, but I do think the NAO/AO are showing a tendency to disobey the typical rules governing them. We've currently got a 4SD block over the Arctic and a 3SD block over Greenland during a strong La Niña; many people were ascribing last winter's incredible blocking to the west-based El Niño, but we have the opposite ENSO and the same thing appears to be happening again. As soon as December rolls around, the polar indices tank just as they did last year. Even if we lose the NAO, it appears the models are latching onto a monster AO block with ridging from Kamchatka amplifying towards the North Pole and bringing much colder air into Canada and eventually to the Northern Tier of the CONUS, particularly the Midwest and the East. It begs the question: What is causing the incredible blocking state in the cryosphere? And will it ever disappear this winter with the La Niña being so strong, or is another factor like solar driving it?

Both the models are individual forecasts keep wanting to say the NAO is breaking down, but then a few days later it reappears or verifies as far more negative than anyone imagined. I think this winter is a weird one to predict as we've got some very conflicting tendencies going on.

I am not sure how to respond to this. If you are suggesting this is why I am forecasting a trough along the West/East Coast and ridge in between then you are wrong. If you are just saying that the 12z run I quoted was wrong...well sure. They are always wrong. That's the beauty of medium/long range forecasting...

I was just saying that the ECM run was an anomaly and not representative of my thoughts about the December pattern. All of a sudden, the ECM is showing continued cold over the Ohio Valley, the Upper Midwest, and the Northeast through Day 10...many of these places were warmer in December 1954 and December 1975, the main analogs you cited. I don't anticipate a huge warm-up given that the AO looks to be ridiculously negative. I also think the Greenland block will return and set up a memorable period around the holidays. It seems as if whenever the NAO fades these days, it comes back even stronger like a week later.

[HM]

Well, the NAO may be governed by many things and all theories may be taken into account but keep in mind that the foundation of predicting this -NAO / cold period for the first half of December was based on AAM/forcing. Looking at a MJO diagram and then composting the h5 heights isn't going to cut it. Also, just because the MJO is in the center, doesn't mean there isn't forcing going on somewhere.

Say what you want but I think the forcing has been suggesting this cold period and I don't think the NAO is simply overpowering the signal. Now, once you form the block, yes it can trump signals for a while...but at some point the Pacific is going to keep sending the block unfavorable wave features until the point where it gets destroyed. The NAO has been negative for a while but the effects have taken a while to be felt, which is typical with the Pacific pattern we have been dealing with. Now with a nice PNA spike, that should amplify the cold for a while. The NAO has had plenty of dips over the last 10 days and will continue for the next 10 days. Are you suggesting another spike late Dec?

Everyone keeps saying the pattern hasn't started yet....true...but the NAO has been negative when the Greenland block first formed a week or so ago. Just because the East hasn't been constantly cold doesn't mean the NAO hasn't been there. So you are basically forecasting a -NAO from 11/20 through 1/1? It's got to give at some point and my guess is after the next solid dip in the first 10 days of December.

All the while, the forcing will continue to grow in the IO/Indonesia through December, making that Pacific sector flow very "fire hose-like" over time.

[nzucker]

Are you suggesting another spike late Dec?

Everyone keeps saying the pattern hasn't started yet....true...but the NAO has been negative when the Greenland block first formed a week or so ago. Just because the East hasn't been constantly cold doesn't mean the NAO hasn't been there. So you are basically forecasting a -NAO from 11/20 through 1/1? It's got to give at some point and my guess is after the next solid dip in the first 10 days of December.

All the while, the forcing will continue to grow in the IO/Indonesia through December, making that Pacific sector flow very "fire hose-like" over time.

I think the NAO will relax a bit around December 10th as the GFS and ECM both show a PV moving towards Greenland in this time frame and breaking down the block. I'm definitely not forecasting a solid -NAO block through 1/1 although I think I'm doing well on saying that it will average negative this winter. I would guess we'll see another strong -NAO emerging around the holidays as the relaxations of the blocking pattern have been short lately, and I remember some previous La Niña winters such as 07-08 that had a cold period right before Christmas after some mildness. Of course, it will be harder to maintain the blocking with the Niña getting stronger and the PV developing naturally as the winter goes on, but I think it will still be there.

I don't think the NAO moderating around 12/10 is the beginning of a pattern change towards warmth for the East and Midwest, however, HM. I still see an Alaska block on the models and that pours some very cold air into Canada. With the northern stream being rather active, some of that cold should be introduced into the CONUS. The 0z GFS shows NYC's 850s staying right around the -7C to -15C range for most of the run, well into the long range, which is well below average. I think most of the cold will pool behind the GoA low in Alaska and Yukon, where the GFS shows a large area of <-30C 850s, but some of that will break off with a North Atlantic ridge still being around and northern stream impulses moving into the Lakes, as well as a +PNA around December 10th. We'll see though.

[CoastalWx]

You're right, it may not completely collapse. That run of the ECMWF did. The point is, after this big cutoff, lower heights replace the big ridge anomaly. Collapse sounds like a good word.

This isn't a warm look for the eastern third and I am by no means forecasting that. More of a variable/seasonal look with cool anomalies near the SE perhaps.

Yeah I threw that edit in there, figuring that's what you meant. We'll see how it responds if the MJO does try to go into phase 4/5 in the next week or so. It looks like the models weaken the block to very near neutral, but then try and rebound later in the month. We'll see what happens/

[jdrenken]

Which do you trust?

1. Models provided by Allan Huffman website
   
2. ESRL...goes without saying
   
3. NCEP...same site.
   

[Yes_Probably_Maybe_No]

Icebox till Christmas FTW

Should probably continue to keep an eye on the IO though

[Amped]

Icebox till Christmas FTW

Should probably continue to keep an eye on the IO though

This marks the second full day of -NAO of the 2010-2011 meterological winter. We are now ahead of 2007-2008

[das]

This marks the second full day of -NAO of the 2010-2011 meterological winter. We are now ahead of 2007-2008

This made me laugh. Thx.

[LakeEffectKing]

Icebox till Christmas FTW

Should probably continue to keep an eye on the IO though

AND building a beautiful NH snowpack!! And SE Canada should fair well and fill in/ build up over the next week:

[NJwinter23]

AND building a beautiful NH snowpack!! And SE Canada should fair well and fill in/ build up over the next week:

supplying a beautiful route for our cold air...How are you making out with the LES in Liverpool?

[Amped]

AND building a beautiful NH snowpack!! And SE Canada should fair well and fill in/ build up over the next week:

I know there was a little snow if France but I think that map is over doing it.