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Medium Range-Long Range thread


NaoPos

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I have a question hopefully any met can chime in with an answer. From what i was quickly taught about mountain torque, specifically the east asian mountain torque. You want the mountain torque to be positive for higher chances of meridonal flow, while negative yields to zonal flow. My question is the current east asian mountain torque is in the negative phase, which from what i was taught would yield a zonal flow. Obviously in the next week or so a big pac ridge is going to develop and maybe a positive pna, which should cause some amplitude in the pattern. Why is it not being shown in the east asain mountain torque? I have heard that the lag is usually 8-14 days, so it should be showing up. Does a pac ridge/positive pna go hand in hand with another phase of a mountain torque? Or is it like other teleconnections where its a decent pattern signaler but not a major one?

 

gltaum.90day.gif

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Euro weeklies have the NE US in below normal temps for weeks 2, 3, and 4 due to a flip to a +PNA pattern which gets even more impressive as time goes on... also has an impressive -NAO/-AO combination.  Precip also goes to near and even above normal weeks 3 and 4, so as far as the weeklies are concerned, it's game on.  Third consecutive run showing this, so yes we can start to believe them. Consistency. Today's weeks 2 and 3 match the previous weeklies runs of weeks 3 and 4 almost to the letter.  I realize weeks 3 and 4 need to be taken with a grain of salt, but so far par for the course matching up to last week's at the same time stamp.  

 

I'm coming after you if this fails :);)

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Congrats Tombo and just want to thank Ampsu19, Tombo, Irishbri, ElkoRay, Phlwx, Rainshshadow, Mitchell, HM, Orh and Wes in cameo roles sharing thoughts and analysis in this thread and the refereshingly intelligent questions from others that spur further discussion....and thanks to all for staying (relatively) on topic in this subforum's medium/long range threads

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Congrats Tombo and just want to thank Ampsu19, Tombo, Irishbri, ElkoRay, Phlwx, Rainshshadow, Mitchell, HM, Orh and Wes in cameo roles sharing thoughts and analysis in this thread and the refereshingly intelligent questions from others that spur further discussion....and thanks to all for staying (relatively) on topic in this subforum's medium/long range threads

 

+1

My head spins when i read some of this stuff but its very interesting and I'm slowly learning the basics.

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Another thing to point out, if global models could accurately predict the MJO in week 2-3, we'd see much better medium range extra-tropical circulation predictions (don't hold me to this, but it seems logical).  Check out the verification for week 2 for this recent MJO event. All the models suggested one solution where reality had the true solution. Even though all the models hum the tune doesn't necessarily mean it is truth.

 

Yeah, the talks I've seen on the reasons why the Euro weeklies are skillful basically all comes down to being able to model the MJO with some skill. Anecdotally, I've seen the same thing. When the Euro weeklies are on point with the MJO, they're pretty good and vice versa.

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The wednesday threat still has some support but it is on life support. The 6z gfs brought it back and its mainly snow for the nw burbs into lehigh valley with sleet/rain at the start switching to snow/rain at the end for the city. Majority of the gefs are colder and have a decent slug of precip with more influence from a banna like high. The euro is showery precip type frontal passage. Ggem keeps the wave on tuesday further south, while developing another wave and bringing that north later wednesday.

 

f138.gif

f108.gif

 

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The wednesday threat still has some support but it is on life support. The 6z gfs brought it back and its mainly snow for the nw burbs into lehigh valley with sleet/rain at the start switching to snow/rain at the end for the city. Majority of the gefs are colder and have a decent slug of precip with more influence from a banna like high. The euro is showery precip type frontal passage. Ggem keeps the wave on tuesday further south, while developing another wave and bringing that north later wednesday.

 

Definately a shot. Still time for models to wobble back and forth.  Several of the GEFS are half decent.

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Still think the models have a lot of sorting out to do with Tues-Wed. I see the EC hanging back the energy and the GFS trying to push things through as fast as possible. I don't think either is right and fit in with typical biases. Canadian actually looked like a better fit to what I see going on next week. Of course my view as usual and not our WFO forecast. 

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6z gfs delivers the -EPO, +PNA,.

u6equpab.jpg

There's somewhat of an -NAO there, (def a -AO) it's just not very strong per se.

0z euro shunts a piece of the pV into western Greenland as it elongates and weakens. (Undoubtedly from the SSW/MMW)

The 0z ECM ENS look better with the -NAO, but it's something that concerns me.

There's no doubt that this is a cold pattern incoming, but it could be the dreaded cold & dry pattern. I believe eat based -NAO's Tend to do that?

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I have a question hopefully any met can chime in with an answer. From what i was quickly taught about mountain torque, specifically the east asian mountain torque. You want the mountain torque to be positive for higher chances of meridonal flow, while negative yields to zonal flow. My question is the current east asian mountain torque is in the negative phase, which from what i was taught would yield a zonal flow. Obviously in the next week or so a big pac ridge is going to develop and maybe a positive pna, which should cause some amplitude in the pattern. Why is it not being shown in the east asain mountain torque? I have heard that the lag is usually 8-14 days, so it should be showing up. Does a pac ridge/positive pna go hand in hand with another phase of a mountain torque? Or is it like other teleconnections where its a decent pattern signaler but not a major one?

 

gltaum.90day.gif

 

I'm guessing that the ridging is being caused by the MJO which is east of the Himalayas longitudinally now.  There's the SSW (-NAO East?) maybe indirectly involved also.  The one good piece of news is that the PV based on the GEFS looks to be settling in or close  to Hudson Bay and they dont like to move from there easily. 

 

Mike and Adam, I'm surmising that the stuck in phase 6/7 outlook of the mjo is a "dollar coast averaging" because of the split between the convective and wind components??? :unsure:

 

 

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6z gfs delivers the -EPO, +PNA,.u6equpab.jpgThere's somewhat of an -NAO there, (def a -AO) it's just not very strong per se.0z euro shunts a piece of the pV into western Greenland as it elongates and weakens. (Undoubtedly from the SSW/MMW) The 0z ECM ENS look better with the -NAO, but it's something that concerns me.There's no doubt that this is a cold pattern incoming, but it could be the dreaded cold & dry pattern. I believe eat based -NAO's Tend to do that?

I would think the west based would be a better shot at dry. If you remember in 09-10 a lot of those storms barely got past NYC do to how far south the pv was displaced allowing the storm to track further south. With an east based nao it's a blocking pattern but not a strong one which would allow the pv to fluctuate further north. If the mjo can get into phase 8-2 like some think into February that should give a kick to the southern jet.

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Could you elaborate on this? Basically are you saying that something else like a rossby wave or kelvin wave is mimicking the mjo which is cause the models to think its does a loop in phases 7-6?

 

Equatorial waves often project onto the RMM PCs, most commonly CCKWs and equatorial Rossby waves (Wheeler and Hendon 2004; Roundy et al. 2010). These waves aren't mimicing the MJO... they are just projecting onto the RMM PCs which causes the line on the phase-space diagram to jump around. Extratropical circulation can also project onto the RMM PCs if within the 15S-15N latitude band. Therefore, these disturbances can all cause "mini" loops within the MJO phase space diagram.

 

Another thing that can throw off the RMM PCs is when the three variables that make RMM (U200, U850, OLR) are out of phase with eachother. For example, U200 could show a 2 sigma signal in phase 6, where U850 is in phase 1 at amplitude of 1 sigma, and OLR is in phase 4 with a 0.85 sigma signal. Since the three components of RMM do not equally contribute to the MJO signal, some days will show U200 driving the RMM, and others with U850. So days when U200 drives the signal, the RMM would track towards phase 6, however other days might show U850 and in that cause it would track towards phase 1. This type of scenario will cause multiple loops and often a dive towards the inner-core, where in reality there could very well be a true MJO signature.

 

I wish I had the 7-14D forecast to diagnose what is causing the GFS to forecast a miniloop. The time-longitude plot of U200 with the GFS forecast appeneded suggests the development of a CCKW at the date line in the next couple of days. This forecast may suggest a miniloop in RMM phase 6-7, but the CCKW appears to be in the broad upper-level easterly phase of the MJO. If a mini-loop does occur, I'd expect a rapid counterclockwise oribit thereafter into phase 8-1.

 

 

u.200.anom.30.5S-5N.gif

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I'm guessing that the ridging is being caused by the MJO which is east of the Himalayas longitudinally now.  There's the SSW (-NAO East?) maybe indirectly involved also.  The one good piece of news is that the PV based on the GEFS looks to be settling in or close  to Hudson Bay and they dont like to move from there easily. 

 

Mike and Adam, I'm surmising that the stuck in phase 6/7 outlook of the mjo is a "dollar coast averaging" because of the split between the convective and wind components??? :unsure:

 

It might be... There's just no way to be certain unless either CPC or matt wheeler creates partial fraction phase space diagrams, similar to what I have on my MJO tab for the VPM. With respect to my VPM indices, U200 and VP200 are in phase with U850. The miniloop at D7 that VPM is starting to suggest appears to be dominated by upper-level signals, which I believe can be attributed to the development of a CCKW near the dateline (see above post).

 

Full VPM with ENSO:

last.90d.RMMPhase.png

 

Parial VPM with ENSO phase space diagrams:

 

 

last.90d.RMMPhase_VP200.pnglast.90d.RMMPhase_U200.pnglast.90d.RMMPhase_U850.png
 
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EC dry and cold. Still not ready to jump off idea of a wave early-mid next week, we'll see.

Seems like the gefs and gem are the robust ones, relatively speaking. The euro on that wave had about a tenth or so for the region. The 850s were below but thicknesses were high not sure if that's frozen or not. Can't see low level temps. Great discussion today guys. Mike hope you are a frequent visitor to our forum your insight is great along with all the other mets.

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