Medium/Long Range thread

[am19psu]

well, looks as if the current cool down is temporary. GFS and EURO both show a lakes cutter or 2. With the ULL sitting in the SW corners and ejecting, just as the NAO goes positive, and the pac ridge retrograding, it's a no brainer that its a cutter pattern as we head into late October,1st half of November. The Northern jet retreats North into Canada, so its pure southern stream energy being depicted on the models now. Adam's 1st flamethrower pic could be posted quite soon.

Still lots of uncertainty in this period (see Sam's thread on the main board). I wouldn't buy either of those solutions yet, but I favor the GFS more than the Euro

[NaoPos]

So reading that roundy is still the way to go? Also, on the AAM plots we are starting to see +AAM after hr 120 is that the polar jet retreating ? Also, I noticed some blues in the 90n zone is that the polar vortex organizing with the +ao?

Can't answer the stuff about the AMM, but the models are showing the polar jet retreat North into Canada.

 

[am19psu]

But you've got a big trough over the Aleutians, mapping to a Wave-1 disturbance which could throw off the AO forecasts

[NaoPos]

But you've got a big trough over the Aleutians, mapping to a Wave-1 disturbance which could throw off the AO forecasts

But as Mike alluded to, the MJO with the CCKW represents warmer Eastern US phase? seems to match up well with the +NAO, +AO regime we're heading into.

[Mike.Ventrice]

I have created these maps of MJO filtered VP200  (shading) for current state, next week forecast, and second week forecast. I would love to test this forecast verse the RMM type forecasts. The contours are Kelvin filtered VP200 anomalies.

 

[Met1985]

Wow great info in here guys. Really learning a lot in this thread. Keep up the great work.

[Mike.Ventrice]

Still lots of uncertainty in this period (see Sam's thread on the main board). I wouldn't buy either of those solutions yet, but I favor the GFS more than the Euro

 

This period is giving me serious head aches! I'm also favoring the GFS more than the Euro here, but that alone is making me feel queezy. 

[Met1985]

But as Mike alluded to, the MJO with the CCKW represents warmer Eastern US phase? seems to match up well with the +NAO, +AO regime we're heading into.

I think what he is saying in the main thread that Sam has made is that we have two recurving tropical systems that could throw a wrench in the forecast and that we have already seen with these systems recurving that it really can throw everything off. I could be wrong though in that analysis.

[am19psu]

But as Mike alluded to, the MJO with the CCKW represents warmer Eastern US phase? seems to match up well with the +NAO, +AO regime we're heading into.

You're absolutely correct that the MJO/CCKW influence favors a warmer east, but that's not the only forcing we're dealing with

[am19psu]

This period is giving me serious head aches! I'm also favoring the GFS more than the Euro here, but that alone is making me feel queezy.

I know, I know...

[am19psu]

I think what he is saying in the main thread that Sam has made is that we have two recurving tropical systems that could throw a wrench in the forecast and that we have already seen with these systems recurving that it really can throw everything off. I could be wrong though in that analysis.

Nope, you got it.

[Rainshadow]

Even without recurving tropical systems, the modeling skill this autumn beyond day 4-5 IMO has not been greater than average.  Case in point the wave on the front we just had yesterday.

[Met1985]

Nope, you got it.

Nice! Lots to learn from yall Mets on here and this is a great thread on the board right know.

[Rainshadow]

You're absolutely correct that the MJO/CCKW influence favors a warmer east, but that's not the only forcing we're dealing with

 

Its about the same time as the effects from the Himalayan Mountain torque should arrive?

[NaoPos]

You're absolutely correct that the MJO/CCKW influence favors a warmer east, but that's not the only forcing we're dealing with

I'm liking the euro at this point. Tropical forcing aside, looking at how the +NAO and polar jet are responding, i don't see why a lakes cutter isn't possible, and warmer temps for us. There seems to be a separation in the jet streams, which makes me think the warmer solution will tend to work out rather than a seasonable or cooler forecast. Just my amateur opinion though. You guys seem to like the GFS. SHould be fun to watch how things unfold. 

[am19psu]

Its about the same time as the effects from the Himalayan Mountain torque should arrive?

Well, that will increase the AAM across the Pacific, which could lead to stronger wave breaking across the SW US, which could theoretically make us warmer. But at the same time, you're going to be dealing with a strong Aleutian Low, which could pump up heights in BC and allow for stronger distubances to dive down out of Canada. Plus, the MJO does favor a building SE ridge. Questions >> Answers.

[Rainshadow]

Well, that will increase the AAM across the Pacific, which could lead to stronger wave breaking across the SW US, which could theoretically make us warmer. But at the same time, you're going to be dealing with a strong Aleutian Low, which could pump up heights in BC and allow for stronger distubances to dive down out of Canada. Plus, the MJO does favor a building SE ridge. Questions >> Answers.

 

Then I looked at this (torquing) all wrong. I thought it would eventually lead to a pos PNA and make us cooler. Am I too fast with the evolution or it does not necessarily break that way?

[am19psu]

Then I looked at this (torquing) all wrong. I thought it would eventually lead to a pos PNA and make us cooler. Am I too fast with the evolution or it does not necessarily break that way?

It can definitely help with that, too. Depends on the structure of the anticyclonic wave breaking. If it happens farther south, like the Euro, then it will add WAA across the Plains/SE US. If it happens farther north, it will help build the PNA.

[Rainshadow]

It can definitely help with that, too. Depends on the structure of the anticyclonic wave breaking. If it happens farther south, like the Euro, then it will add WAA across the Plains/SE US. If it happens farther north, it will help build the PNA.

 

Thanks Adam!

[CVA]

 

 

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

 

 

Thanks. I had a look at 925hPa zonal wind anomalies near the equator in 5 strong El Nino years and 5 strong La Nina years. November to March.

 

It seems to me that eastwards of about 120W to 60E, the anomalies are very small. 

 

Ogling these pictures suggests that in the La Nina case, the anomalous westerlies from the central Indian Ocean through to maritime continent would "cancel out" the anomalous easterlies from the western Pacific to the central Pacific. They appear to cover roughly equivalent degrees of longitude and roughly equivalent anomalies.

Meanwhile, the reverse would appear to be true in the El Nino case. 

 

I don't see this 260 degree extent during La Nina where I'm supposed to be seeing +u wind anomalies? I can only see about 80 degrees (60E to 140E). 

 

 

Data for El Nino: 

195711 196511 197211 198211 199711 195712 196512 197212 198212 199712 195801 196601 197301 198301 199801 195802 196602 197302 198302 199802 195803 196603 197303 198303 199803 

Data for La Nina:

197311 197511 198811 199911 201011 197312 197512 198812 199912 201012 197401 197601 198901 200001 201101 197402 197602 198902 200002 201102 197403 197603 198903 200003 201103

[tombo82685]

These are my thoughts on where i think this pattern is heading for the next 2 weeks. I'm siding with euro ens right now. 

As you can see from the global picture for 3 days from now, the tropical systems that are recurving are actually causing a -epo to form, with a split flow forming on the west coast. With a cutoff low over the southwest and ridging from the northwest pacific coast into canada/alaska. 

 

 

 

Now, i think the euro ens mean is the way to go here. This day ten euro ens mean h5 setup. With the response to the recurving tropical systems we can see a -epo was established. Below that is the cutoff off the sw pacific coast, which is the system in question for halloween timeframe. The Atlantic side of things, we have a north atlantic ridge popping up, with a +nao. Wit the -epo setup/split flow on the west coast and the north atlantic ridge offshore, the downstream trofiness should translate to over the eastern third of the USA.

 

 

 

Now in terms of the mjo, the h5 pattern isn't to far off the progged pattern from the euro ens. 

The current MJO right now is phase 2, but i circled the mjo phases next week which is phjase 3 heading into phase 3

Now the corresponding h5 patterns for phase 3-4 for november is

 

Its not a perfect match, but they do show a general average to little below average for the east cost. While the west coast features a general ridge, but the -epo sources don't match up to well.

 

 

The east asian mt torque has been pretty positive since about october 15, which usually is indicative of meridonal flow, which may support the increase in the heights along the west coast into alaska.

 

 

Last be not least, the area that i circled, i think is response from the recurving typhoon. I'm Like 40% on this since i don't know much about the AAM. But i think that +AAM is the -epo ridge popping which is givng the illusion of the polar jet retreating.

 

After this i think we should begin a warm period after nov 7 as the mjo heads into phases 5-6 which are warmer than normal for the east. Also, some of the ensembles want to slowly bring a lobe of thatpv over siberia and work it south over alaska. This would then knock out that -epo and kick everything eastward. Feel free to hammer this hahaa. I just want here some other input on this.

[HM]

Thanks. I had a look at 925hPa zonal wind anomalies near the equator in 5 strong El Nino years and 5 strong La Nina years. November to March.

It seems to me that eastwards of about 120W to 60E, the anomalies are very small.

Ogling these pictures suggests that in the La Nina case, the anomalous westerlies from the central Indian Ocean through to maritime continent would "cancel out" the anomalous easterlies from the western Pacific to the central Pacific. They appear to cover roughly equivalent degrees of longitude and roughly equivalent anomalies.

Meanwhile, the reverse would appear to be true in the El Nino case.

I don't see this 260 degree extent during La Nina where I'm supposed to be seeing +u wind anomalies? I can only see about 80 degrees (60E to 140E).

Data for El Nino:

195711 196511 197211 198211 199711 195712 196512 197212 198212 199712 195801 196601 197301 198301 199801 195802 196602 197302 198302 199802 195803 196603 197303 198303 199803

Data for La Nina:

197311 197511 198811 199911 201011 197312 197512 198812 199912 201012 197401 197601 198901 200001 201101 197402 197602 198902 200002 201102 197403 197603 198903 200003 201103

I went back and now know what's wrong. In fact, you indicated what at the bottom of your first post. It is an issue of time that is messing with you.

The westerly surface winds with el nino in tropical pacific mean the frictional effect is weak. The atmosphere ends up speeding up and the earth slows. This added westerly momentum develops a STJ and speeds up the Mid Latitude jet in Pacific. Friction again cannot win because of the excess and the air remains faster.

It seems like you were jumping ahead to how the whole thing weakens. There also can be low AAM el nino winters too.

[CVA]

I went back and now know what's wrong. In fact, you indicated what at the bottom of your first post. It is an issue of time that is messing with you.

The westerly surface winds with el nino in tropical pacific mean the frictional effect is weak. The atmosphere ends up speeding up and the earth slows. This added westerly momentum develops a STJ and speeds up the Mid Latitude jet in Pacific. Friction again cannot win because of the excess and the air remains faster.

It seems like you were jumping ahead to how the whole thing weakens. There also can be low AAM el nino winters too.

 

I much appreciate you spelling this out for me. I'm afraid I can never restrain my inner toddler and ceaselessly have to ask "why". In this case, why is the frictional effect weak? Friction must be everpresent, and increases in response to the wind speed (I know this is non-linear, but it should be generally true). In that case, how is it ever possible for friction to be incapable of reducing the increased westerly AAM? 

Also, wouldn't it be the case that friction dominates at low levels (though can gradually mix upwards in the boundary layer, and perhaps higher) but would have next to no impact on a synoptic upper level jet? 

When we look at vertical integrals of AAM, which levels dominate? Although wind speeds are greater at upper levels, the atmospheric mass is less, therefore, do all levels roughly contribute equally? 

[JamieOber]

Tombo,

 

Boy are there ever some awful winter analogs in there. I guess a few good ones but 2001 (shudder). 

[tombo82685]

Tombo,

 

Boy are there ever some awful winter analogs in there. I guess a few good ones but 2001 (shudder). 

yea 2001-2002 was horrible, only 4 inches of snow for philly that year. 3rd warmest on record.

[NaoPos]

well, after the cool shot sat-tues, looks like we go back to -pna, +NAO, look for a few days.

say hello to mr.SE RIDGE :-)

[HM]

I much appreciate you spelling this out for me. I'm afraid I can never restrain my inner toddler and ceaselessly have to ask "why". In this case, why is the frictional effect weak? Friction must be everpresent, and increases in response to the wind speed (I know this is non-linear, but it should be generally true). In that case, how is it ever possible for friction to be incapable of reducing the increased westerly AAM? 

Also, wouldn't it be the case that friction dominates at low levels (though can gradually mix upwards in the boundary layer, and perhaps higher) but would have next to no impact on a synoptic upper level jet? 

When we look at vertical integrals of AAM, which levels dominate? Although wind speeds are greater at upper levels, the atmospheric mass is less, therefore, do all levels roughly contribute equally? 

 

Again, this is a very difficult concept differentiating between speed and momentum. Friction and westerly flow in the Mid Latitudes are always happening. We aren't saying these things are stopping. If the westerlies have intensified, this is a product of added momentum exceeding the effects of frictional dissipation. This added momentum can be from a mountain torque a couple of days ago or perhaps a wave train or convection. 

 

All exchanges with the Earth happen at the surface and the only sources/sinks for AAM are at the surface. AAM can be transported through the middle-upper troposphere / lower stratosphere but it can never be a source/sink. It can give an overall tendency or state of circulation that may affect the surface torques, but it cannot cause an AAM anomaly directly.

[Rainshadow]

well, after the cool shot sat-tues, looks like we go back to -pna, +NAO, look for a few days. say hello to mr.SE RIDGE :-)

 

Looks like a rather blase first half of November with Mr. PV near the pole. Starting to look at week2 NAEFS and they continue to hover around near normal-above normal temps.

[NaoPos]

well, looks as if the current cool down is temporary. GFS and EURO both show a lakes cutter or 2. With the ULL sitting in the SW corners and ejecting, just as the NAO goes positive, and the pac ridge retrograding, it's a no brainer that its a cutter pattern as we head into late October,1st half of November. The Northern jet retreats North into Canada, so its pure southern stream energy being depicted on the models now. Adam's 1st flamethrower pic could be posted quite soon.

Looks like the models were keen on sniffing out the upcoming pattern. Aside from a day 1-3 day cool

Shot sat-mon, we should warm up quite nicely and see an influence from the SE ridge.

Edit*, now that I think of it, I believe that image link was hot linked, so it was time sensitive. I do believe the euro picked up on the warmer solution however.

[JamieOber]

Haven't seen anyone comment on this elsewhere so figured I'd ask...is this legit?: https://www.facebook.com/notes/wxriskcom/-alert-major-development-for-the-winter-of-2013-14-negative-nao-is-likely/595932400454022