Medium/Long Range thread

[tombo82685]

The op euro keeps us under some pretty strong ridging for most of it's medium-long range. Let the Indian summer continue: The ensembles agree, and I'd have to agree with how the pacific is acting.

it doesn't help the MJO died in a warm phase for us Combined with thepacific as you stated, its a warm look. The euro ens do edge cooler in the 11-15 day period. After the 15 is probably when we will see some sort or cooler regime, but that's not earth shattering considering the dailies are edging cooler to. The mjo seems dead till atleast the end of the month.

The analog map for the 8-14 day outlook. That picture looks warm and dry, with storms cutting to the west most of the time and meh cool fronts coming through. Need that pacific ridge to build east more so. A lot of the anaolgs on that composite show pretty much a warm 2/3rds of october with a seasonal to slightly below last 5-10 days

[NaoPos]

Just a quick glance @ the 18z gfs, you can see it's trying to sniff out a change in the NPAC jet stream. Gotta see what drives the possible change? MJO looks to go into phase 7, then into the cOD.

Current NPAC:

Forecasted 276:

[am19psu]

Anyone watching what's going to happen in the tropics over the next week? Maybe some signs of the global circ pattern changing (finally) as we head into the meat of fall.

[Mike.Ventrice]

Anyone watching what's going to happen in the tropics over the next week? Maybe some signs of the global circ pattern changing (finally) as we head into the meat of fall.

 

It's about time.  I was forecasting a pattern flip 2 months ago to happen in Oct. Just need temps to verify below average for the East.  Prob will get burned out West though (I thought ridging would bring temps up to above average standards late in the month but with the magnitude of cold anomalies the first week of the month, don't see that happening anymore).

 

[tombo82685]

It's about time.  I was forecasting a pattern flip 2 months ago to happen in Oct. Just need temps to verify below average for the East.  Prob will get burned out West though (I thought ridging would bring temps up to above average standards late in the month but with the magnitude of cold anomalies the first week of the month, don't see that happening anymore).

 

 

Mike, glad to see you back here posting. Is your mjo stuff on your site updated? Roundy's mjo hasn't updated since oct 1.

[tombo82685]

Te euro ens 10-15 day temp anomaly does cool off the region to normal values, with the coldest weather displaced over the rockies and pacific coast.

[Mike.Ventrice]

Mike, glad to see you back here posting. Is your mjo stuff on your site updated? Roundy's mjo hasn't updated since oct 1.

 

Yes sir.. I presume Paul isn't getting NOAA interpolated OLR since ESRL turned off their access as a result of the Gov't shut down. You can find my MJO stuff here:http://mikeventrice.weebly.com/mjo.html and the time-longitude plots are of MJO filtered VP200/850 data are on http://mikeventrice.weebly.com/forecast.html

[Rainshadow]

Yes sir.. I presume Paul isn't getting NOAA interpolated OLR since ESRL turned off their access as a result of the Gov't shut down. You can find my MJO stuff here:http://mikeventrice.weebly.com/mjo.html and the time-longitude plots are of MJO filtered VP200/850 data are on http://mikeventrice.weebly.com/forecast.html

Mike,

 

Thank-you for sharing your time with us.

[Mike.Ventrice]

Mike,

 

Thank-you for sharing your time with us.

No prob! I'd like to contribute more to these discussions but am loosely restricted to publicly posting about tropical cyclone stuff. I still read the discussions time to time and contribute when I feel it's appropriate  

[tombo82685]

No prob! I'd like to contribute more to these discussions but am loosely restricted to publicly posting about tropical cyclone stuff. I still read the discussions time to time and contribute when I feel it's appropriate

Mike, i remember last year at the end of winter time you posted the gwo on here that you put on your site. Could you explain what that is? The best phases we need for cold/snowy? Is it like the mjo, where each phase changes during a different month? Lol and can you dumb it down for us, so we can try to comprehend it?

[Mike.Ventrice]

Mike, i remember last year at the end of winter time you posted the gwo on here that you put on your site. Could you explain what that is? The best phases we need for cold/snowy? Is it like the mjo, where each phase changes during a different month? Lol and can you dumb it down for us, so we can try to comprehend it?

 

Ah yes, it's found on: http://mikeventrice.weebly.com/misc-oscillations.html

 

Or: 

 

The GWO is basically in an index that measures the exchange of atmospheric angular momentum with the surface of the Earth. A paper was published by Weickmann and Berry (2008/or 2009) about it, search AMS journals for it. They claim it's an index that includes information about the MJO, but since it's a global integrated index of zonal wind anomalies over all levels of the atmosphere, they claim there are other modes of variability incorporated into this index, such as variability caused by mountain torque and extra-tropical variability. Each phase of the index represent a different state of the GWO. When youre in Phases 2-3, you are in a low-AAM state. Typically during strong La Ninas, you'll spin around down here for most of the season. Phases 6+7 are high AAM states (El Nino's...). You often don't see big orbits in this index during NH Summer. 

 

There's some useful information from this index, but the limit of predictability is about 7 days. Beyond that, the models cannot predict it and thus it's not very useful on most occasion of medium-range predictability. However it does have some seasonal implications but just if it's above the zero line (high aam), or below (low aam). Google the Global Wind Oscillation and check out the images to see what happens during each of the 4 states of the GWO.

[am19psu]

The more I learn about AAM, the less I like the GWO. Even though I'm not a huge fan of the Wheeler MJO plots, there is a lot more information contained in them than the GWO plots, imo. You're better off looking at the actual zonally integrated AAM or AAM tendency and individual torque plots to gain insight into the AAM cycle.

[Mike.Ventrice]

The more I learn about AAM, the less I like the GWO. Even though I'm not a huge fan of the Wheeler MJO plots, there is a lot more information contained in them than the GWO plots, imo. You're better off looking at the actual zonally integrated AAM or AAM tendency and individual torque plots to gain insight into the AAM cycle.

 

Agreed. The more you look into the GWO, the less appealing it is. There's just so much noise in the index, it makes it difficult to use. 

[tombo82685]

The more I learn about AAM, the less I like the GWO. Even though I'm not a huge fan of the Wheeler MJO plots, there is a lot more information contained in them than the GWO plots, imo. You're better off looking at the actual zonally integrated AAM or AAM tendency and individual torque plots to gain insight into the AAM cycle.

 

The AAM is the mountain torque, correct? If so, that information is on hold because of the shutdown?

[tombo82685]

Ah yes, it's found on: http://mikeventrice.weebly.com/misc-oscillations.html

 

Or: 

 

The GWO is basically in an index that measures the exchange of atmospheric angular momentum with the surface of the Earth. A paper was published by Weickmann and Berry (2008/or 2009) about it, search AMS journals for it. They claim it's an index that includes information about the MJO, but since it's a global integrated index of zonal wind anomalies over all levels of the atmosphere, they claim there are other modes of variability incorporated into this index, such as variability caused by mountain torque and extra-tropical variability. Each phase of the index represent a different state of the GWO. When youre in Phases 2-3, you are in a low-AAM state. Typically during strong La Ninas, you'll spin around down here for most of the season. Phases 6+7 are high AAM states (El Nino's...). You often don't see big orbits in this index during NH Summer. 

 

There's some useful information from this index, but the limit of predictability is about 7 days. Beyond that, the models cannot predict it and thus it's not very useful on most occasion of medium-range predictability. However it does have some seasonal implications but just if it's above the zero line (high aam), or below (low aam). Google the Global Wind Oscillation and check out the images to see what happens during each of the 4 states of the GWO.

Thanks! So from that diagram, in september the gwo was in a low nino state, while right now its pretty much neutral? I imagine the height vertically that the gwo shows, shows how strong either el or la nina is?

[CoastalWx]

While I'm not an expert, I agree with Adam and Mike. The trends that you can discern on the AAM timelines seem much more valuable. For instance those higher AAMs trending north on the timeline probably would lead to higher confidence on northward displaced westerlies and perhaps a +AO for example. Or vice-versa. 

[am19psu]

The AAM is the mountain torque, correct? If so, that information is on hold because of the shutdown?

Mountain torque changes AAM. AAM stands for atmospheric angular momentum. It can be increased or decreased by mountain, friction or Coriolis torques. It can be fluxed by changes in the global wind patterns (which doesn't change the total values of AAM, but changes its spatial distribution). Since total angular momentum is conserved by definition, when AAM is higher than normal, the earth's rotation slows down and vice versa. The GWO plots AAM anomalies on the y-axis and d(AAM)/dt (i.e. AAM tendency) on the x-axis.

[tombo82685]

Mountain torque changes AAM. AAM stands for atmospheric angular momentum. It can be increased or decreased by mountain, friction or Coriolis torques. It can be fluxed by changes in the global wind patterns (which doesn't change the total values of AAM, but changes its spatial distribution). Since total angular momentum is conserved by definition, when AAM is higher than normal, the earth's rotation slows down and vice versa. The GWO plots AAM anomalies on the y-axis and d(AAM)/dt (i.e. AAM tendency) on the x-axis.

So is their a plot for the AAM, or do you use the gwo for it?

[am19psu]

So is their a plot for the AAM, or do you use the gwo for it?

There is, but it is shutdown right now

[Mike.Ventrice]

Sorta looks like this but is an analysis: 

[tombo82685]

Sorta looks like this but is an analysis: 

Mike or Adam, you don't read that like the mjo with +/-olr. This has to do with winds right?

[HM]

The AAM is the mountain torque, correct?

 

Any easterly surface wind (opposes Earth's spin) will act as a momentum source (since the Earth will have to exchange +AAM upwards with the air). Therefore, the Tropics/Easterlies are a source of momentum and the Mid-Latitude westerlies are a sink, where friction usually eats the excess +AAM. If anomalous low pressure develops west of a mountain chain, particularly one placed significantly along longitude lines, and anomalous high pressure develops east, then the mountain will oppose Earth's Rotation even more than it already would have. Friction again will usually eat the excess +AAM (usually over oceans) produced by mountains.

 

The reason the GWO is confusing is because there are many different forces that produce "power spectra signatures" of coherence in AAM. All of the processes I mentioned above can happen for many reasons on many different time scales. Larger looping GWOs are usually associated with intraseasonal oscillations (MJO) while quick loops are due to this internal "mountain-friction" cycle in the Mid Latitudes.

 

I hoped this helped.

[tombo82685]

Any easterly surface wind (opposes Earth's spin) will act as a momentum source (since the Earth will have to exchange +AAM upwards with the air). Therefore, the Tropics/Easterlies are a source of momentum and the Mid-Latitude westerlies are a sink, where friction usually eats the excess +AAM. If anomalous low pressure develops west of a mountain chain, particularly one placed significantly along longitude lines, and anomalous high pressure develops east, then the mountain will oppose Earth's Rotation even more than it already would have. Friction again will usually eat the excess +AAM (usually over oceans) produced by mountains.

 

The reason the GWO is confusing is because there are many different forces that produce "power spectra signatures" of coherence in AAM. All of the processes I mentioned above can happen for many reasons on many different time scales. Larger looping GWOs are usually associated with intraseasonal oscillations (MJO) while quick loops are due to this internal "mountain-friction" cycle in the Mid Latitudes.

 

I hoped this helped.

So let me just try to grasp this. Say you have a strong low coming into the pacific coast. The Rockies, which run longitudinally, and you have a high dropping down in the plains or over the great lakes, this would cause an acceleration in momentum source? Is their a bottom line where a low pressure has to be this strong or in this spot or a high pressure has to be this strong for acceleration to start? Or is it just any low pressure west of a mtn chain and high pressure east of a mtn chain will cause acceleration?

[HM]

 

So let me just try to grasp this. Say you have a strong low coming into the pacific coast. The Rockies, which run longitudinally, and you have a high dropping down in the plains or over the great lakes, this would cause an acceleration in momentum source? Is their a bottom line where a low pressure has to be this strong or in this spot or a high pressure has to be this strong for acceleration to start? Or is it just any low pressure west of a mtn chain and high pressure east of a mtn chain will cause acceleration?

I think the issue you're having is that this is "momentum exchange with the Earth" and isn't a process that happens at some moment. The synoptic-planetary scale waves happen in a couple days, sure, but the effects continue beyond. So the low-high positioning along mountains is enough to become a source (I suppose the stronger the anomalies and easterly wind, the stronger the source). Overtime, westerly flow will increase in response to this "traffic-jam" as the Earth's Rotation transfers the +AAM upward. Therefore, the Earth ends up slowing down as the Mid Latitude Jet ends up speeding up after the pressure perturbation.

It's weird to try to grasp things like momentum and waves when looking at the usual plots we look at in 2d etc. These are not processes that you can really see at some time without context and moving forward/backward in time.

[toronto blizzard]

What are your thoughts on the pattern going forward HM?

[HM]

 

What are your thoughts on the pattern going forward HM?

There is no doubt about it that we have seen an eastward shift in the Walker Cell, bringing the strongest uplift into the W. PAC (with intraseasonal oscillations every-so-often biasing us toward El Nino-like). Times of oceanic Kelvin Wave-convection coupling can bring El Nino-like periods of wave positioning, hence some of the forecast analogs (many are El Nino years) we are seeing and modeled solutions for later Oct. The typhoon-aided expansion of the ridge in the NW PAC will promote further poleward ridging downstream in each of the Hadley Cell subsidence zones. I suspect after we get beyond this "stratospheric hiccup" with early-season wave 1 / EP heat flux, the vortex will rapidly intensify in November. In fact, the PV should get into better alignment then, consolidating throughout the stratosphere in a classic position NW of Scand. The only thing that has me confused on that is the 30 hpa equatorial temperatures are still rather cool, despite the +QBO. Between that and the poleward u=0 wind line in the stratospheric subtropics, it is possible disturbances between 70-30 hpa will continue to keep the vortex out of z-alignment. If this ends up happening, it could mean a much colder scenario unfolds Nov-Dec.

Unfortunately, the gov't shutdown has limited my analysis and tools. As we go through an El Nino-like period soon, we should see a strengthening +AO state...despite the cooler air / NE PAC ridging through then. My best guess is that, eventually, the warmth should return in November and the caveats that I mentioned will fail to disturb the PV from formly correctly. An extreme example of when it didn't in these early stages was 2010...

[am19psu]

There is no doubt about it that we have seen an eastward shift in the Walker Cell, bringing the strongest uplift into the W. PAC (with intraseasonal oscillations every-so-often biasing us toward El Nino-like). Times of oceanic Kelvin Wave-convection coupling can bring El Nino-like periods of wave positioning, hence some of the forecast analogs (many are El Nino years) we are seeing and modeled solutions for later Oct. The typhoon-aided expansion of the ridge in the NW PAC will promote further poleward ridging downstream in each of the Hadley Cell subsidence zones. I suspect after we get beyond this "stratospheric hiccup" with early-season wave 1 / EP heat flux, the vortex will rapidly intensify in November. In fact, the PV should get into better alignment then, consolidating throughout the stratosphere in a classic position NW of Scand. The only thing that has me confused on that is the 30 hpa equatorial temperatures are still rather cool, despite the +QBO. Between that and the poleward u=0 wind line in the stratospheric subtropics, it is possible disturbances between 70-30 hpa will continue to keep the vortex out of z-alignment. If this ends up happening, it could mean a much colder scenario unfolds Nov-Dec.

Unfortunately, the gov't shutdown has limited my analysis and tools. As we go through an El Nino-like period soon, we should see a strengthening +AO state...despite the cooler air / NE PAC ridging through then. My best guess is that, eventually, the warmth should return in November and the caveats that I mentioned will fail to disturb the PV from formly correctly. An extreme example of when it didn't in these early stages was 2010...

I actually understood 90% of that.

[tombo82685]

Way above my head, but from what i gathered from that...after this cool shot coming we most likely will get into a warmer pattern for november and into early dec unless those disturbances keep the pv parked away from the pole giving a -AO instead of a +AO 

[HM]

 

I actually understood 90% of that.

 

lol...maybe by this time next week, it will be 99%...closer to my acceptable range! 

Basically all i got out of that was...after this cool shot coming we most likely will get into a warmer pattern for november and into early dec unless those disturbances keep the pv parked away from the pole giving a -AO instead of a +AO

No doubt the cold beforehand will be impressive, likely targeting the C States the hardest. But this kind of pattern can bring some flakes even into the Northeast. It would be something if we pulled off another weird autumn snow event. The tedency for a SE ridge may fight against that opportunity, especially if we fail to get an appreciable west-based -NAO signal. On a semi-related note, it would be nice to have ESRL back and everything else that currently is down really.

[am19psu]

lol...maybe by this time next week, it will be 99%...closer to my acceptable range!

you lost me on the poleward stratospheric u=0 line, but otherwise, I got it.