Medium Range-Long Range thread

[Rainshadow]

First off, its not really getting delayed,  the euro and the gfs were to quick. The gefs have held with a change around the 18/20.

 

2nd, don't expect any substantial cold until that pac ridge moves east.

 

3rd. The euro has 2 winter threats post 180 hrs solely for the interior like the nw burbs on north and west. One is a swfe where the city may see something very brief. The other is more of an rdg to abe north look with another swfe

 

 

 

Yeah the GFS has been pretty much steady with a cold blast starting around the 18th.  The Euro did lose the day 10 closed ridge over Greenland pretty quickly, but then again we would be talking 14th-15th with that one anyway.  Looks like maybe one more day and the week2 NAEFS should not be in the warm percentages. At anyrate, like you posted there is going to be alot of cold air in Canada just a question as to where it enters the conus. 

[NaoPos]

Not a bad Look on he 180hr 18z GFS:

the -NAO look is returning after being lost for a few runs.The west coast ridge moves east and the mean axis of if spils the cold air eastwards.

Lets hope that -NAO is legit. Otherwise, if* (another legit concern) that west coast ridge verifies, the PV gets pushed towards Greenland as causes a +NAO. GFS did this a few runs on the operation. I wonder if its having issues with the ongoing strat warming and how that propagates donwards to the tropopause. Lots going on, but its looking better than before. The -NAO signal is better looking than the end of Decembers. Frankly, but the PV built up some nice cold air in canada. Once(IF*) that breaks down and weakens, we'll have some cold air spill south.

You can officially call this the IF* blog.

[tombo82685]

Yeah the GFS has been pretty much steady with a cold blast starting around the 18th.  The Euro did lose the day 10 closed ridge over Greenland pretty quickly, but then again we would be talking 14th-15th with that one anyway.  Looks like maybe one more day and the week2 NAEFS should not be in the warm percentages. At anyrate, like you posted there is going to be alot of cold air in Canada just a question as to where it enters the conus. 

 

yup, the naefs are getting there

 

[tombo82685]

0z euro has frozen precip event from pa tpk north next wednesday

 

[tombo82685]

that's a nice look on the euro ens with an east based -nao, -ao, and -epo pinching off the vortex under it over hudson bay. While their is still somewhat of a se ridge to bring storm close.

 

 

 

[Allsnow]

0z euro has frozen precip event from pa tpk north next wednesday

Then the cold comes, which looks like a good pattern for clippers. Fwiw

[Quakertown needs snow]

euro / gfs still lookis interesting with precip next week, something for the winter folks to look forward during upcoming heat wave.

 

[tombo82685]

naefs in the 8-14 day are now at normal for the region

 

[chubbs]

Nice longer range model trend to moving colder air further east. 06 GEFS are getting close to a MA snowstorm look by day 12. With  low heights in maritimes and no SE ridge. Seasonably cold here.

[am19psu]

Not sure why anyone was expecting anything colder than normal before Jan 20. The base state of the atmosphere is -PNA this season. Until you get something to disrupt that (e.g. MJO), we're not going to see a favorable snow pattern, even if the AO is negative. We had some KW activity at the end of the December that helped dislodge the -PNA. Now, we'll get some MJO help at the end of the month through early Feb.

 

Also not sure why everyone is so bullish on this MJO wave dying? Because of what happened in late Nov-early Dec? There was an obvious (in hindsight) reason for that MJO wave dying - the tropical tropopause got a lot warmer, killing large scale tropical convection. Now the tropopause is cooling again and another robust wave has started. Unless we something weird happen again with the tropical tropopause, the MJO wave should be robust and perform a full orbit.

[tombo82685]

Not sure why anyone was expecting anything colder than normal before Jan 20. The base state of the atmosphere is -PNA this season. Until you get something to disrupt that (e.g. MJO), we're not going to see a favorable snow pattern, even if the AO is negative. We had some KW activity at the end of the December that helped dislodge the -PNA. Now, we'll get some MJO help at the end of the month through early Feb.

 

Also not sure why everyone is so bullish on this MJO wave dying? Because of what happened in late Nov-early Dec? There was an obvious (in hindsight) reason for that MJO wave dying - the tropical tropopause got a lot warmer, killing large scale tropical convection. Now the tropopause is cooling again and another robust wave has started. Unless we something weird happen again with the tropical tropopause, the MJO wave should be robust and perform a full orbit.

 

Glad to see you have returned from your hiatus with good news. Thought you abandoned us. For your sake lets hope it does loops in phases 8-2

[chubbs]

 

Also not sure why everyone is so bullish on this MJO wave dying? Because of what happened in late Nov-early Dec? There was an obvious (in hindsight) reason for that MJO wave dying - the tropical tropopause got a lot warmer, killing large scale tropical convection. Now the tropopause is cooling again and another robust wave has started. Unless we something weird happen again with the tropical tropopause, the MJO wave should be robust and perform a full orbit.

Hits a brick wall in 7 according to many modell forecasts. Could be the difference between a cold period and a seasonable or even mild period here for the end of the month..

[am19psu]

Hits a brick wall in 7 according to many modell forecasts. Could be the difference between a cold period and a seasonable or even mild period here for the end of the month..

 

Obviously. But the dynamical models suck beyond 7 days. Just because the plots are created doesn't mean they are particularly useful.

[tombo82685]

Obviously. But the dynamical models suck beyond 7 days. Just because the plots are created doesn't mean they are particularly useful.

 

roundy shows phases 8-2, with the current wave dying in phase 9-1 and a new one firing up around phase 2

[am19psu]

roundy shows phases 8-2, with the current wave dying in phase 9-1 and a new one firing up around phase 2

 

That's all the same wave, imo, you just lose the signal over the W Hemisphere.

[chubbs]

Obviously. But the dynamical models suck beyond 7 days. Just because the plots are created doesn't mean they are particularly useful.

Whats driving the MJO amplitude ramp-up? Coincides nicely with increasing flow amplification in NA that has been in the cards for a while.

[NaoPos]

Obviously. But the dynamical models suck beyond 7 days. Just because the plots are created doesn't mean they are particularly useful.

Whats driving the MJO amplitude ramp-up? Coincides nicely with increasing flow amplification in NA that has been in the cards for a while.

I'f im not mistaken, a burst of westerlies in the trade winds:

which coincides with this map:

if you look towards the INdian Ocean, the green outlines (indicating lift) and the sat images of the corresponding tropical disturbances:

(note, Indian Ocean is on the right)

Maybe Adam can tell you more. Thats just my understanding.

[am19psu]

Whats driving the MJO amplitude ramp-up? 

 

I'd win a Nobel prize if I could tell you that definitively. It's tied to the cooling tropical tropopause, though.

[chubbs]

Thanks. I was wondering if conditions in mid-latitudes were feeding back to tropics by influencing position and strength of sub tropical ridges or some other mechanism.

[am19psu]

Thanks. I was wondering if conditions in mid-latitudes were feeding back to tropics by influencing position and strength of sub tropical ridges or some other mechanism.

 

There is definitely some of that that occurs (think the GWO and GSDM arguments from Weickmann and Berry), but they are not well understood. That's part of the reason why stat models are so much better than dynamical models. We don't physically understand what causes the MJO and how it's modulated.

[chubbs]

There is definitely some of that that occurs (think the GWO and GSDM arguments from Weickmann and Berry), but they are not well understood. That's part of the reason why stat models are so much better than dynamical models. We don't physically understand what causes the MJO and how it's modulated.

Makes sense that time frame for dynamic model predictabiltyi is similar for MJO and mid-latitude sytems. The upcoming period will be a good test since no dynamic model on CPC site gets past 7.

[am19psu]

Makes sense that time frame for dynamic model predictabiltyi is similar for MJO and mid-latitude sytems. The upcoming period will be a good test since no dynamic model on CPC site gets past 7.

 

Same thing happened back in October. No model had it getting past P2 and it went all the way around to P6 before dying. And it died because things I don't understand in the tropical stratosphere, not ENSO or anything else I read at the time.

[Mike.Ventrice]

Not sure why anyone was expecting anything colder than normal before Jan 20. The base state of the atmosphere is -PNA this season. Until you get something to disrupt that (e.g. MJO), we're not going to see a favorable snow pattern, even if the AO is negative. We had some KW activity at the end of the December that helped dislodge the -PNA. Now, we'll get some MJO help at the end of the month through early Feb.

 

Also not sure why everyone is so bullish on this MJO wave dying? Because of what happened in late Nov-early Dec? There was an obvious (in hindsight) reason for that MJO wave dying - the tropical tropopause got a lot warmer, killing large scale tropical convection. Now the tropopause is cooling again and another robust wave has started. Unless we something weird happen again with the tropical tropopause, the MJO wave should be robust and perform a full orbit.

 

 

Glad to see you have returned from your hiatus with good news. Thought you abandoned us. For your sake lets hope it does loops in phases 8-2

 

 

Hits a brick wall in 7 according to many modell forecasts. Could be the difference between a cold period and a seasonable or even mild period here for the end of the month..

 

 

Obviously. But the dynamical models suck beyond 7 days. Just because the plots are created doesn't mean they are particularly useful.

 

 

roundy shows phases 8-2, with the current wave dying in phase 9-1 and a new one firing up around phase 2

 

 

That's all the same wave, imo, you just lose the signal over the W Hemisphere.

 

 

Whats driving the MJO amplitude ramp-up? Coincides nicely with increasing flow amplification in NA that has been in the cards for a while.

 

 

Makes sense that time frame for dynamic model predictabiltyi is similar for MJO and mid-latitude sytems. The upcoming period will be a good test since no dynamic model on CPC site gets past 7.

 

 

Hi all,

 

I just wanted to comment on the MJO weakening in Phase 7. I just cut and paste this from a different sub forum without knowledge of this discussion going on. Adam made me aware of this forum's discussion and would just like to quickly share this with you. There was a nice medium range discussion from Buffalo's NWS on Monday, that is what I am alluding to:

 

This was a great discussion! I'm glad to see this in a NWS WFO discussion. This discussion is in agreement with what Adam and I spoke about on this forum in December. The only thing that concerns me is the discussion of the weakening of the MJO event... Most dynamical and statistical models will always show a weakening of the MJO when it tranverses around the Western Hemisphere. In this case, the dynamical models hold onto this MJO signal, but statistical approaches like Paul Roundy's will show a weakening of the MJO over the Western Hemisphere. This weakening is not a true weakening, and is a biproduct of the MJO speeding up over the Western Hemisphere, taking the shape of a strong convectively-coupled Kelvin wave. Therefore, space-time filtering techinques (like Paul's) will weaken MJO filtered anomalies and replace them with Kelvin filtered anomalies.

[NJwinter23]

Obviously. But the dynamical models suck beyond 7 days. Just because the plots are created doesn't mean they are particularly useful.

 

Adam, how do you feel about the EC idea of stalling things/looping around the 6/7 border for a time before continuing through 8-1-2? what tends to cause these loops/stalls to occur usually, is it low level easterly winds? we do have some widespread easterlies at 850 across most of the pacific

[am19psu]

Adam, how do you feel about the EC idea of stalling things/looping around the 6/7 border for a time before continuing through 8-1-2? what tends to cause these loops/stalls to occur usually, is it low level easterly winds? we do have some widespread easterlies at 850 across most of the pacific

 

There's a lot of KW activity forecasted around the same time and near the same location as MJO wave. MJOs don't retrogress (like, by the equations of motion), so I assume it is just some of the KW signal leaking into the Wheeler plots.

[tombo82685]

 

first time i have seen this on the gefs. Retrogrades the pac ridge over the Bering straights, and starts to bring on trofiness on the west coast with the se ridge coming back to play. Not good if that would occur

[NJwinter23]

There's a lot of KW activity forecasted around the same time and near the same location as MJO wave. MJOs don't retrogress (like, by the equations of motion), so I assume it is just some of the KW signal leaking into the Wheeler plots.

 

Ah that would make sense. Thanks for the explanation. 

[HM]

There's a lot of KW activity forecasted around the same time and near the same location as MJO wave. MJOs don't retrogress (like, by the equations of motion), so I assume it is just some of the KW signal leaking into the Wheeler plots.

Yeah but KW do not regress either. I agree that KW interact, amplify and suppress the MJO wave signal which can cause "weirdness" on the charts. As the Walker intensifies / CHI fields tighten, the SST gradient/trades may be enough to cause the forcing to stall for a bit, possibly showing this "loop" as the propagation dies. Yes I understand that the models weaken the MJO in the C-E PAC for the reasons already known/stated, but this loop may not be because of that solely.

BTW, CPC AO page has the 50-10mb temperature anomalies:

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.shtml

[HM]

Hi all,

 

I just wanted to comment on the MJO weakening in Phase 7. I just cut and paste this from a different sub forum without knowledge of this discussion going on. Adam made me aware of this forum's discussion and would just like to quickly share this with you. There was a nice medium range discussion from Buffalo's NWS on Monday, that is what I am alluding to:

 

This was a great discussion! I'm glad to see this in a NWS WFO discussion. This discussion is in agreement with what Adam and I spoke about on this forum in December. The only thing that concerns me is the discussion of the weakening of the MJO event... Most dynamical and statistical models will always show a weakening of the MJO when it tranverses around the Western Hemisphere. In this case, the dynamical models hold onto this MJO signal, but statistical approaches like Paul Roundy's will show a weakening of the MJO over the Western Hemisphere. This weakening is not a true weakening, and is a biproduct of the MJO speeding up over the Western Hemisphere, taking the shape of a strong convectively-coupled Kelvin wave. Therefore, space-time filtering techinques (like Paul's) will weaken MJO filtered anomalies and replace them with Kelvin filtered anomalies.

I, of course, agree with your explanations on why the MJO typically weakens into these phases but I should also point out that there is a climatology here. When the forecasts are for a loop into phase 6-7, this isn't quite the same thing as what you are saying and I'm worried you are putting too much emphasis on this idea that they are likely "too weak." There is a real Walker Cell conflict with a semi-La Nina-like state over the C PAC. It is a real possibility the convection hits a brick wall, stops the propagation and weakens/loops the MJO. Having said that, I don't think this necessarily means we fail at making it to 8-1-2 either. I think we do make it eventually.

Also, one thought about the SSW and the MJO. I have read the papers about the MJO influencing the stratosphere and I agree that it does. But keep in mind, we have been sparking warmings from Asia long before the sudden "MJO wake up." There is a relationship between AO/AAO warmings and their subsequent equatorial coolings which can promote MJO growth. As the Pac Jet retracted, the EA jet took a break, allowed the +AAM to grow in the "Walker Favored" areas of the equatorial regions which also played a role.

[chubbs]

Today's Euro 10 day looks like its heading to a big MA or SE snowstorm. With massive 50/50 and closed low in southern stream