Medium/Long Range thread

[Quakertown needs snow]

Euro bringing some pretty chilly air for this time of the year. Highs could be in upper 40s to low 50s for highs in the 7-10 day period. Good shot of first frost and freeze in that time frame to.

yeah euro has been sniffing it out the last several runs.

looking forward to the chill.

looks like lake effect snows may kick in.

[CT Rain]

Sorry to hear but understood.  Awesome stuff as usual HM. 

 

Sorry to hear as well... but I understand. This thread has been a great resource full of great information... keep it flowing!!

[chubbs]

some pretty decent analog years on that list...

 Us old timers start to get excited when 60/61 starts showing up on analog lists. Also a cool neutral ENSO winter

[CVA]

In an El Nino, the amount of westerly AAM produced in the tropical-subtropical latitudes exceeds the amount of it that the friction can eat in the Mid-Latitudes. Therefore, the westerly flows extend into the Mid Latitudes, extending the Pacific Jet and anchors in the Aleutian Low. The propagation of these westerlies may look linear but it is in fact the Hadley Cell that allows for the propagation (even though the exchange of momentum happens solely at the surface). The increased westerly flows from the tropical latitudes also helps intensify the STJ and in some cases more than the PJ. This creates an environment favorable for split flow, blocking and wave breaking.  

 

Re: the first sentence. It sounds like you're saying that in El Nino, the tropical latitudes are (relatively) an even greater source of AAM than they usually are, and the mid-latitudes are (relatively) a weaker sink of AAM than they usually are. Through poleward transport of momentum, this excess AAM from the tropics transfer to the mid-latitudes and the effects are as you say. 

Am I on course so far?

What I have trouble comprehending is how this state of affairs can be maintained? In El Nino we see weakened trade winds, so westerly anomalies across the tropics at low levels. Since friction opposes will always oppose the surface wind, this should add -AAM in the tropics, and surely counteract the situation that got us here to begin with? 

Equally, in order to begin in a situation where "the amount of westerly AAM produced in the tropical-subtropical latitudes exceeds the amount of it that the friction can eat in the Mid-Latitudes", surely the tropics themselves must be experiencing easterly anomalies near the surface (hence invoking a frictional torque transferring +AAM from the earth to the atmosphere), which sounds rather La Nina like. If not, then where did this surplus of tropical +AAM come from in the first place? 

 

In general I have trouble with the timeframes involved in the combined AAM and d/dt (AAM) processes. Even if I am careful to separate these out (and I'm not sure that I am), I am usually baffled by how the atmosphere can maintain itself in any one phase (or phase "areas") for any reasonable length of time.

 

Thanks  

[tombo82685]

Still feeling as we head into the first week of november we should start to warm up again after the week of chilly air.  The mountain torque also shows the next week cool shot with the positive east asian mtn torque, signaling a stong chance of meridnal flow. The north american mt torque, being negative since late september has correlated well with the -nao

 

 

It will be interesting to see if the gfs or euro's mjo forecast is right.  The gfs is showing a strong mjo wave entering phase 1 which would keep the colder air around longer. While the euro has it briefly in phase 1 and develops a decent wave in phase 2-3/ The 11-15 day euro temp anomalies show normal to slightly below normal over the eastern US, with the west coast being above. 

 

The mjo, which is coming out of phase 6, which correlates well to the -nao, will head into phase 1-2. Phase which have the cold air first entering mid section then working east. The roundy mjo, then shows a decently strong wave in phase 3 which is a warm phase for the east coast around the beginning of november.

[tombo82685]

Ok, here is my graphic that i have dug up for the AAM now that the map rooms are up and running. How do you read this map? Also it seems like its only what occurring right now, do they have forecast that go out for a week or so?

 

[am19psu]

Ok, here is my graphic that i have dug up for the AAM now that the map rooms are up and running. How do you read this map? Also it seems like its only what occurring right now, do they have forecast that go out for a week or so?

http://mikeventrice.weebly.com/misc-oscillations.html

I can explain later, unless HM or Mike V get to it first

[am19psu]

Ok, here is my graphic that i have dug up for the AAM now that the map rooms are up and running. How do you read this map? Also it seems like its only what occurring right now, do they have forecast that go out for a week or so?

So the way I read that is that we've had weaker than normal trades since September (warm colors in the tropics) and a poleward displaced polar jet in October (warm colors near 50N) with no subtropical jet influence (cool colors around 30N).

[tombo82685]

So the way I read that is that we've had weaker than normal trades since September (warm colors in the tropics) and a poleward displaced polar jet in October (warm colors near 50N) with no subtropical jet influence (cool colors around 30N).

Ok, that helps a good bit...My question is, what do the colors represent? yellows weak blues, and greens strong?

[am19psu]

Ok, that helps a good bit...My question is, what do the colors represent? yellows weak blues, and greens strong?

warm colors = +AAM anomalies (more westerly momentum than normal), cool colors = -AAM anomalies (less westerly momentum than normal)

[tombo82685]

warm colors = +AAM anomalies (more westerly momentum than normal), cool colors = -AAM anomalies (less westerly momentum than normal)

 

Ok so looking at this forecast, weak trade winds +AAM, and later in the forecast period its on the verge to switching over to -aam. Now with the subtropical jet, Their is little influence in the beginning of the period with the cool colors and -aam. Towards hr 120, we get some stj influence and +aam that eventually goes back to weak stj influence after hr 168 with -aam. In terms of polar jet, I'm lost but i can see it has -aam, but it looks like it may be displaced south with the cool colors? lol or am i reading backwards, the warm colors north of 30n is the polar jet south

[HM]

 

Re: the first sentence. It sounds like you're saying that in El Nino, the tropical latitudes are (relatively) an even greater source of AAM than they usually are, and the mid-latitudes are (relatively) a weaker sink of AAM than they usually are. Through poleward transport of momentum, this excess AAM from the tropics transfer to the mid-latitudes and the effects are as you say. 

Am I on course so far?

What I have trouble comprehending is how this state of affairs can be maintained? In El Nino we see weakened trade winds, so westerly anomalies across the tropics at low levels. Since friction opposes will always oppose the surface wind, this should add -AAM in the tropics, and surely counteract the situation that got us here to begin with? 

Equally, in order to begin in a situation where "the amount of westerly AAM produced in the tropical-subtropical latitudes exceeds the amount of it that the friction can eat in the Mid-Latitudes", surely the tropics themselves must be experiencing easterly anomalies near the surface (hence invoking a frictional torque transferring +AAM from the earth to the atmosphere), which sounds rather La Nina like. If not, then where did this surplus of tropical +AAM come from in the first place? 

 

In general I have trouble with the timeframes involved in the combined AAM and d/dt (AAM) processes. Even if I am careful to separate these out (and I'm not sure that I am), I am usually baffled by how the atmosphere can maintain itself in any one phase (or phase "areas") for any reasonable length of time.

 

Thanks

 

Let's make this simple:

El Nino +u wind location across equatorial belt: 140E-120W ~ 100° of longitude

La Nina +u wind location across equatorial belt: 120W-140E ~ 260° of longitude

[HM]

 

Sorry to hear but understood.  Awesome stuff as usual HM.

 

 

Sorry to hear as well... but I understand. This thread has been a great resource full of great information... keep it flowing!!

 

Thanks guys...

Again, this isn't about your regular posters or off-topic bantering etc. I am not on some quest to change the forum and I do not think any one person is at fault. If I am going to be hassled over and over again by posters with non-scientific reasoning and trolling, and then be encouraged by the staff to fight it instead of it being taking care of by the mods, then your subforum isn't for me...simple as that. I do not have the time or strength to deal with that anymore.

I understand the kind of forecasting I do can naturally cause opposition, especially by snow-hungry, impatient posters. In the face of my contributions and what were basically near-perfect LR forecasts for your area last winter, I was still being trolled. I was being trolled during prior events (before it got very snowy) that I thought weren't going to be great snowstorms yet for your area, etc. And then I was trolled in the days before the great blizzard because models weren't showing the event yet. There are always terrible posters, but my experience on Americanwx is a lot better not being involved with that kind of posting (and encouragement by the staff to fight it).

[am19psu]

Ok so looking at this forecast, weak trade winds +AAM, and later in the forecast period its on the verge to switching over to -aam. Now with the subtropical jet, Their is little influence in the beginning of the period with the cool colors and -aam. Towards hr 120, we get some stj influence and +aam that eventually goes back to weak stj influence after hr 168 with -aam. In terms of polar jet, I'm lost but i can see it has -aam, but it looks like it may be displaced south with the cool colors? lol or am i reading backwards, the warm colors north of 30n is the polar jet south

The most important thing I see there is the appearance of the subtropical jet at T+120 to T+168. That's partially related to the MJO push and probably due to some enhanced wave activity over the subtropical Pacific. BTW, that's why I'm not entirely writing off the event next week. The only other thing of note that I see is that the polar jet is likely in the right position, but with less momentum than usual, meaning the pattern is somewhat blocked up globally.

[tombo82685]

The most important thing I see there is the appearance of the subtropical jet at T+120 to T+168. That's partially related to the MJO push and probably due to some enhanced wave activity over the subtropical Pacific. BTW, that's why I'm not entirely writing off the event next week. The only other thing of note that I see is that the polar jet is likely in the right position, but with less momentum than usual, meaning the pattern is somewhat blocked up globally.

Ok so i was right with the stj getting active in that short time. Couple of questions...is there a guide as to what patterns occur with +aam and -aam? I would imagine -aam would lead to zonal flow? while +amm is meridonal? What are the latitude that dictate everything? That is the one problem i am having like distinguishing between  where the polar,stj, and the trade wind zones are. Like obviously, the equator is 0 but how far north do the trade winds go? How far south is the polar jet zones and how far south and north do the stj go? Does that make sense?

[am19psu]

is there a guide as to what patterns occur with +aam and -aam?

Not really, unfortunately. That's why I don't like the GWO so much.

 

I would imagine -aam would lead to zonal flow? while +amm is meridonal?

Backwards. +AAM is more zonal, -AAM is more meridional.

 

What are the latitude that dictate everything?

Varies by season and with other things like ENSO state, QBO state, PV state, what's going on over the Tibetan Plateau, etc. There aren't any hard and fast rules, unfortunately. You just have to keep watching it to get a feel for how to use it.

That is the one problem i am having like distinguishing between  where the polar,stj, and the trade wind zones are. Like obviously, the equator is 0 but how far north do the trade winds go? How far south is the polar jet zones and how far south and north do the stj go? Does that make sense?

In winter, the polar jet is usually between 40-50N and the subtropical jet between 20-30N. Trades usually don't extend farther than 10-15 degrees from the equator.

[tombo82685]

The most important thing I see there is the appearance of the subtropical jet at T+120 to T+168. That's partially related to the MJO push and probably due to some enhanced wave activity over the subtropical Pacific. BTW, that's why I'm not entirely writing off the event next week. The only other thing of note that I see is that the polar jet is likely in the right position, but with less momentum than usual, meaning the pattern is somewhat blocked up globally.

How did you come up with the polar jet being blocked up? Is there a normal speed at which the jet runs?

[am19psu]

How did you come up with the polar jet being blocked up? Is there a normal speed at which the jet runs?

negative aam anomalies with no corresponding positive anomalies

[tombo82685]

The most important thing I see there is the appearance of the subtropical jet at T+120 to T+168. That's partially related to the MJO push and probably due to some enhanced wave activity over the subtropical Pacific. BTW, that's why I'm not entirely writing off the event next week. The only other thing of note that I see is that the polar jet is likely in the right position, but with less momentum than usual, meaning the pattern is somewhat blocked up globally.

Euro swings that southern energy off the carolinas...then takes the energy diving down from the plains and turns that into a miller B. Cold rain with highs in the mid 40s next thurs

[tombo82685]

Anyone have any archived AAM links just so i can compare things and figure how to better read those maps?

[Mitchell Gaines]

Euro swings that southern energy off the carolinas...then takes the energy diving down from the plains and turns that into a miller B. Cold rain with highs in the mid 40s next thurs

Yup, this solution came on strong throughout the day yesterday. Though Wednesday afternoon/evening timing for more of the rain at this point. Wouldn't be surprised at MPO for a brief mix at the end. 850 mb temps around -4 and surface temps around 35. 

[Mitchell Gaines]

Yup, this solution came on strong throughout the day yesterday. Though Wednesday afternoon/evening timing for more of the rain at this point. Wouldn't be surprised at MPO for a brief mix at the end. 850 mb temps around -4 and surface temps around 35. 

- NAO state going to positive also supports storm idea

. 

[Heisy]

GFS has hopped on the idea as well, good Upper NE snowstorm...what kind of high temps could we be looking for after this storm/front passes in the Philly metro area? 

[Quakertown needs snow]

GFS has hopped on the idea as well, good Upper NE snowstorm...what kind of high temps could we be looking for after this storm/front passes in the Philly metro area? 

phl gfs6z, 2mTemp, Max, Min

[Rainshadow]

I look at fall systems as to when are the models locking into a reasonable consistent outcome (vs the widow-maker storms or the all clears of longer ranges).  Want to see the 12z run, but it looks like its been around 120 hrs from the time of event on average.

[tombo82685]

GFS has hopped on the idea as well, good Upper NE snowstorm...what kind of high temps could we be looking for after this storm/front passes in the Philly metro area? 

The euro has temps in the 45-50 range, with .5-1 of rain for that storm. Yesterdays 12z euro run had colder temperatures overall with a couple days not getting out of the 40s and lows below freezing for the burbs. It even had philly going below later on in the 8-10 day period. The current 0z run has highs in the 50-55 range for fri-sun. Lows in the low to mid 30s for the city. the euro ens mean temps for the city are pretty well matched up with the operational run with highs in the low to mid 50s. Lows though are a little warmer with 35-40. Also should note at looking at the individual ens members, 16 of the 52 show .25 ore more for next wednesdays potential storm.

[tombo82685]

I look at fall systems as to when are the models locking into a reasonable consistent outcome (vs the widow-maker storms or the all clears of longer ranges).  Want to see the 12z run, but it looks like its been around 120 hrs from the time of event on average.

The euro, moved it east compared to yesterdays 12z run. Pretty much keeps it an i95 on east "event"

[tombo82685]

the euro ensembles in the 11-15 day still keep the general theme of west warm, east of the rockies cool. Has -2-5 temp anomalies over the region.

[tombo82685]

Euro has now taken the raw rainy day out for wednesday. Still chilly, but no rain except maybe the jersey shore.

[Rainshadow]

Euro has no taken the raw rainy day out for wednesday. Still chilly, but no rain except maybe the jersey shore.

It could be a looooonnnngggg winter.  The GFS had it, the Euro didnt. Then they both didnt, Then the Euro had it and the GFS didnt, Then they both had it. Now the Euro is losing it.

 

Looks like the short wave should be over Alaska for the 00z run.