A few pattern thoughts

[usedtobe]

The Euro and GEFS ensemble mean forecasts at 240 are both showing a negative nao developing in the mean but they differ significantly over the Pacific. The GEFS shifts the pesky AK upper low west to near the Berring sea and that allows a flat ridge and positive PNA look to develop. That helps a trough develop over the eastern u.S. and at it looks like we'd get a shot of cold weather for a couple of days at the very least. In terms of snow the pattern would be better if the heights around and just south of nova scotia showed a hint of a negative anomaly so I don't see it yet as a snow pattern but. A negative NAO and positive PNA look would be the best one we've had this year.

The euro however, keeps the big low farther east over Ak and continues to show a strong negative PNA look even though the look in the atlantic is better than that of the GFS. Note how it shows a negative anomaly near nova scotia. However, its 500h pattern over the u.s is pretty much a seasonal one. Not a torch but not real cold either. Give me the Euro atlantic and the GFS pacific and I'd be a happy boy.

The GEFS ensemble members continue to forecast AO index to fall into the negative range. That's a nice change from what they have been so far this year. The one big caveat is that correlation scores suggest that the models have done a really poor job in forecasting the strength of the polar vortex.

The same ensemble members are also predicting that the negative PNA pattern may change but note in the long range forecasts do show the PNA pattern switching. Essentially the GEFS ensembles are at war with the euro ensembles about have fast any retrogression might occur.

The typical nina state is to have a negative pNA more than a positive one but in weak nina years, that's not always true. That's the dilemma. Our chances of getting a 4 inch or greater snowstorm were 3.4 times higher with a positive PNA index than with a negative one for the period since 1950.

While I think it is a decent bet that sometime in the 1st week or two of feb we pop a pna ridge along the west coast, I'm not confident in the GFS timing and I'd lean somewhat towards the Euro ens mean but not with much confidence. The ukmet, euro and GEFS forecasts of the mjo pretty much stall it in phase 6. If you look at the temp composite below it's a pretty good match for a negative pna and is more like the euro ens than the GEFS,

Anyway, a few thoughts on the pattern. let's hope for a euro-gefs hybrid sometime in early feb.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/new.nao_index_ensm.html

[Feb]

I'll chime in...

Ens are warmer...0C up to NH/MA border at 150 whereas the op had it on the south coast. 0.25" QPF runs up to CYSC fwiw. In the 11-15d...the upper low starts to take shape over AK again around Barrow. There's a weak ridge axis running from Iceland to Greenland so we should see some confluence to our NE. By d14 that semblance of an AK vortex becomes a trough in the mean and we see ridging along the entire pacific coast of NAMER up through the Yukon. So maybe a weak +PNA -NAO? It looks like nothing impressive, but good enough to have some chances this time of the year.

I took this from the NE forum Wes. I believe some up in that forum have access to the Euro Ensembles that run out to 360 hours. It sounds like the euro does shift to a somewhat +PNA after 240 hours with a -nao also.

[Amped]

So there's a 99% chance of the pattern sucking and a 1% chance of it being good.

[Kmlwx]

So there's a 99% chance of the pattern sucking and a 1% chance of it being good.

Hmm...you and I must have very different ways of reading the same post.

[Amped]

Hmm...you and I must have very different ways of reading the same post.

I was kind of enjoying wes's post until he showed the MJO Phase 6 picture, and stated MJO Phse 6 was the most likely thing to actually verify.

[Kmlwx]

I was kind of enjoying wes's post until he showed the MJO Phase 6 picture.

Well to be fair, it doesn't completely cut off our chances to be in phase 6 - it just reduces them by a good bit. We could still eke out little nickel and dime events.

[Amped]

Well to be fair, it doesn't completely cut off our chances to be in phase 6 - it just reduces them by a good bit. We could still eke out little nickel and dime events.

I want a million bucks but sometimes when I find a nickle on the ground, I leave it there for someone who needs it a lot more than I do.

[usedtobe]

I took this from the NE forum Wes. I believe some up in that forum have access to the Euro Ensembles that run out to 360 hours. It sounds like the euro does shift to a somewhat +PNA after 240 hours with a -nao also.

I hope that's true. the GEFS still pretty much keeps the pos pna look at 240 while the operational euro still has a neg look.

[Deck Pic]

I hope that's true. the GEFS still pretty much keeps the pos pna look at 240 while the operational euro still has a neg look.

Nice post. Maybe we will just need to time a good pattern for a couple days versus something locking in. Like mid Feb 2006.

[usedtobe]

Nice post. Maybe we will just need to time a good pattern for a couple days versus something locking in. Like mid Feb 2006.

That's what I'm hoping. I doubt the -pna will last thru all of Feb and it sounds like from some of the comments that the euro ens do pop a pna pattern with a neg nao sometime in the 1st week of Feb. Even without that I think the euro atlantic might be good enough to get us some love.

[Kmlwx]

That's what I'm hoping. I doubt the -pna will last thru all of Feb and it sounds like from some of the comments that the euro ens do pop a pna pattern with a neg nao sometime in the 1st week of Feb. Even without that I think the euro atlantic might be good enough to get us some love.

- That's the kind of Wes we like to see!

[rduwx]

Thanks for post Wes! Appreciate your thoughts.

[Met1985]

Great post Wes. Thanks for all the info!

[usedtobe]

- That's the kind of Wes we like to see!

It's still talking about Feb and at that time range....it's a big crapshoot. I should ahve said the Euro Atlantic might be good enuf to give us some love beyond 240 hrs and it might not be.

[H2O]

It's still talking about Feb and at that time range....it's a big crapshoot. I should ahve said the Euro Atlantic might be good enuf to give us some love beyond 240 hrs and it might not be.

correction: crap chute

The fact that you can see some reasons for things to be better is good enough. A few of us(Matt,Bob, me to an extent) have all been watching to see if this -NAO is the real deal. I still think that if the Atl is in better shape then we stand a better chance than what we have seen the last 2 months

[Bob Chill]

12z gfs kinda loses the idea of building heights over greenland in the lr but it totally compensates it with a nice big ridge out west. Still some improvement in the atl but nothing exciting. Euro still likes the -nao but it is at odd with the gfs irt the ridge out west (so what else is new)

It's interesting how much the gfs wants to pump up the ridge out west. A really cold look in these parts out in 300+hr fantasyland.

I'm at least confident in a decent +pna after the west finishes getting dumped on from the pac. Still liking our prospects for the first 10 days of Feb even if we don't get a nice -nao to set up.

So much for the blazing torch too. Seasonably warm next week and then it looks like we get some good troughing (even if transient) in these parts towards the end of the month.

[Wonderdog]

12z gfs kinda loses the idea of building heights over greenland in the lr but it totally compensates it with a nice big ridge out west. Still some improvement in the atl but nothing exciting. Euro still likes the -nao but it is at odd with the gfs irt the ridge out west (so what else is new)

It's interesting how much the gfs wants to pump up the ridge out west. A really cold look in these parts out in 300+hr fantasyland.

I'm at least confident in a decent +pna after the west finishes getting dumped on from the pac. Still liking our prospects for the first 10 days of Feb even if we don't get a nice -nao to set up.

So much for the blazing torch too. Seasonably warm next week and then it looks like we get some good troughing (even if transient) in these parts towards the end of the month.

As some have already said, it appears the torch was over-hyped by some. But it's what the info was saying at the time. Now it says something else. So this year at least, any attempt to forecast patterns seems to be foolhardy.

[usedtobe]

12z gfs kinda loses the idea of building heights over greenland in the lr but it totally compensates it with a nice big ridge out west. Still some improvement in the atl but nothing exciting. Euro still likes the -nao but it is at odd with the gfs irt the ridge out west (so what else is new)

It's interesting how much the gfs wants to pump up the ridge out west. A really cold look in these parts out in 300+hr fantasyland.

I'm at least confident in a decent +pna after the west finishes getting dumped on from the pac. Still liking our prospects for the first 10 days of Feb even if we don't get a nice -nao to set up.

So much for the blazing torch too. Seasonably warm next week and then it looks like we get some good troughing (even if transient) in these parts towards the end of the month.

The 18Z gefs ens mean lost not only the NAO but the AO, both turn back positive. That's possible with the vortex again strengthening. Let's hope it's a glitch. I plan on doing a feb CWg piece late next week. Each month, my confidence in the monthly thoughts have goen down.

[Bob Chill]

The 18Z gefs ens mean lost not only the NAO but the AO, both turn back positive. That's possible with the vortex again strengthening. Let's hope it's a glitch. I plan on doing a feb CWg piece late next week. Each month, my confidence in the monthly thoughts have goen down.

Not saying the gfs is right (and I certainly hope it isn't) but one of my concerns about having such a strong and stubborn high latitude pattern is whether is can be "flipped" so to speak. It's been shuffled around a bit lately and that is a really good thing but it really wouldn't surprise me if we reverted back to what we've been seeing quite a bit of in Nov-Dec instead of having it all work in our favor.

Feb may end up being a month that requires the pna to produce on its own in these parts while the ao/nao in general stay in positive territory.

I only understand the MJO phases in general and not how and why it behaves the way it does. GEFS wants to move it along through phases 5-6 through the end of the month. Sure would be nice to see it push through 7-8-1 before winter is basically over.

[WinterWxLuvr]

As some have already said, it appears the torch was over-hyped by some. But it's what the info was saying at the time. Now it says something else. So this year at least, any attempt to forecast patterns seems to be foolhardy.

I think this has to be given consideration. I don't know that I'd have said foolhardy, but definitely perilous.

Just look at how the MJO forecasts have jumped around. Look at what the major global models were predicting for this upcoming week 10 days ago. According to Bob's (I think) AO stats posted a while back, if the AO (currently near neutral?) were to go firmly back into positive range, it would constitute one of the longest positive (generally) AO streaks in history. Bob, I read what you wrote about the pattern at high lats being hard to completely change, but it has to change sooner or later. Otherwise, you're looking at history in the making.

At least the pattern we are in is producing chances for small events. At least it is winter weather. I'm not going to sweat 10-15 day forecasts.

[Bob Chill]

According to Bob's (I think) AO stats posted a while back, if the AO (currently near neutral?) were to go firmly back into positive range, it would constitute one of the longest positive (generally) AO streaks in history. Bob, I read what you wrote about the pattern at high lats being hard to completely change, but it has to change sooner or later. Otherwise, you're looking at history in the making.

I doubt were going back to sustained 2-3+ stand devs for the AO but an overall positive regime for the remainder of winter is possible and not unheard of. 88-89 was the +AO winter that stands out on its own. There was only one day where it was negaitve but it stayed positive to very positive for the entire stretch of Dec-Mar. We've already done better than that this winter so no worries there. This time of year the AO isn't as important though. The NAO and PNA will drive a nice winter pattern for us even if the AO is neutral or pos neutral. I think the odds are in our favor for at least one if not 2 decent patterns before it's time to pack it up for the year and I'm hoping one of them is during the first 10 days of Feb.

I don't like seeing the stupid vortex getting stronger on any model right now. If the vortex gets its act going again around the pole it will be frustrating to say the least. We have had a significant change around the pole recently but it didn't do everything we need. I'm not full of negativity though. I'll leave that to Wes.......j/k of course. He's the realist with deep scientific knowledge about this stuff. I'm just a number cruncher.

[BethesdaWX]

00z Euro Ensembles are starting to drift towards the GFS a bit in the 6-10 day period. Personally I think things look better than they ever have for February and March..I think we just need to wait for models to catch onto the changes coming.

My opinion, Pattern changes involve a major reshuffling of energy and the processes in how it is handled, drawn, and transferred, there has to be a large scale 'reason' for it..and to do that requires energy initially so it is a feedback process.......ENSO is the system's energy base state, to come out of an ENSO event reqires just as much energy variation from "equilibrium" as it required to go into it. So it is an extended process, very rarely do we see a sudden flip and have it sustain, but rather flips that take between 4-6 weeks have a purpose, to re-establish balance, and in this case we have a BIG one on the way, and it has been going on since around New Years.

The heavy global cooling we've seen within the past 2 weeks is a sign of it [less thermal energy [[feedback from ENSO base]] driving the kinetic portion of the budget], a sign of imbalance/reshuffling. This pattern change that began gradually around New Years is still continuing, and IMO will take another ~ 15-20 days to fully complete. But towards the end of the process things should rapidly tumble into the new regime and lock in. February, March, April, and May should all be below average around here, I feel. The Sun is the initiator but the process occurs terrestrially, much like internal variablity.

[usedtobe]

Not saying the gfs is right (and I certainly hope it isn't) but one of my concerns about having such a strong and stubborn high latitude pattern is whether is can be "flipped" so to speak. It's been shuffled around a bit lately and that is a really good thing but it really wouldn't surprise me if we reverted back to what we've been seeing quite a bit of in Nov-Dec instead of having it all work in our favor.

Feb may end up being a month that requires the pna to produce on its own in these parts while the ao/nao in general stay in positive territory.

I only understand the MJO phases in general and not how and why it behaves the way it does. GEFS wants to move it along through phases 5-6 through the end of the month. Sure would be nice to see it push through 7-8-1 before winter is basically over.

Bob, the euro ens still look to be on the warm said for the next 10 days. the AO is only forecast to be weakly negative, essentially for all intents pretty much neutral despite the slight negative value when calculated.

The operational Euro actually has the ao positive (not shown). The euro ens also keep the pna pattern negative except for one transitory bump to positive. That suggests the trough won't be in the east. The AO and PNA combo still is not a good one for us.

[Bob Chill]

Bob, the euro ens still look to be on the warm said for the next 10 days. the AO is only forecast to be weakly negative, essentially for all intents pretty much neutral despite the slight negative value when calculated.

[

I just posted in the feb spec thread about what I though about last nights euro and the 0z gfs. -NAO pretty much gone. No real surprise there. Both models want to build a ridge out west. With no real -nao I assume that we need to time a flawed or nickel and dime event. Zwyts is all over it with the pattern. We may hit 10" this year but it will take 5+ events to get there.

[usedtobe]

I just posted in the feb spec thread about what I though about last nights euro and the 0z gfs. -NAO pretty much gone. No real surprise there. Both models want to build a ridge out west. With no real -nao I assume that we need to time a flawed or nickel and dime event. Zwyts is all over it with the pattern. We may hit 10" this year but it will take 5+ events to get there.

I think it doubtful we'll see 10 inches as we'll probably have to nickel and dime are way though I suspect we still have not seen our biggest snow of the season around the city. I may use your less than 1 degree feb temp composite in my CWG piece for Feb. I'm not sure yet.

[Bob Chill]

I think it doubtful we'll see 10 inches as we'll probably have to nickel and dime are way though I suspect we still have not seen our biggest snow of the season around the city. I may use your less than 1 degree feb temp composite in my CWG piece for Feb. I'm not sure yet.

I compared my Feb temp map for +AO Decembers with the recent one I pulled for weak Nina's. Very different look out west and in the northern plains but both showed the MA pretty much normal for temps. The patterns behind the 2 maps are probably pretty far apart but the end result was the same.

In my limited knowledge, it seems safe to put more weight on Nina climo at this point than just looking at the AO teleconnection for Feb. The +AO regime appears to have its back broken (finally for god sakes). Without have much of a science background, I have a simplistic approach to forecasting weather based mostly on statistics and odds. With that being said, I think my Nina Feb composite isn't a bad call for temps in these parts unless I'm missing some important pieces to the pattern (and I probably am).

[Ellinwood]

My thoughts on the February pattern:

It's a hell of a pattern to try and forecast with the huge amount of uncertainty in the 6-15 day... it'll be fun to watch unfold, though. More sustainable cold but not still probably around +1 on the temps overall based on what I've got for February analogs.

[usedtobe]

My thoughts on the February pattern:

It's a hell of a pattern to try and forecast with the huge amount of uncertainty in the 6-15 day... it'll be fun to watch unfold, though. More sustainable cold but not still probably around +1 on the temps overall based on what I've got for February analogs.

I think even the 6-15 day forecast is a coin flip. Hopefully as the week progresses, the signs will get a little clearer.

[eurojosh]

Scientists find massive bulge of cold freshwater in northern Pac:

http://www.bbc.co.uk/news/science-environment-16657122

Could PNA etc be impacted by this?

[donsutherland1]

Great discussion, Wes. It will be interesting to see how some of the differences between the GFS ensembles and ECMWF ensembles are resolved and how February actually plays out. Unfortunately, I don't believe there will be a dramatic weakening of the current La Niña event.