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Early December Pattern Discussion


Baroclinic Zone

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The cutters in this pattern aren't even real cutters lol. They aren't bringing the cold air from Canada on the backside.

The N PAC ridge is not nearly far enough north...it looks more like the displaced Aleutian ridge that we saw in warm winters like 98-99. There's no extension poleward as we had last year in Winter 10-11, which would knock those low heights out of the Beaufort Sea and extending back towards Siberia. Also, the progressive Atlantic isn't holding any cold shots in...we get one average day and then spike into the 40s the next day. We need to get rid of that massive Icelandic Low.

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The N PAC ridge is not nearly far enough north...it looks more like the displaced Aleutian ridge that we saw in warm winters like 98-99. There's no extension poleward as we had last year in Winter 10-11, which would knock those low heights out of the Beaufort Sea and extending back towards Siberia. Also, the progressive Atlantic isn't holding any cold shots in...we get one average day and then spike into the 40s the next day. We need to get rid of that massive Icelandic Low.

The AO is the hemispheric problem that is dictating much of everything else I think. It's extremely difficult to get a significant +PNA or an -EPO or a -NAO when the entire hemisphere is against blocking.

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The AO is the hemispheric problem that is dictating much of everything else I think. It's extremely difficult to get a significant +PNA or an -EPO or a -NAO when the entire hemisphere is against blocking.

While there hasn't been a massive -EPO, I believe it has been negative several times in recent weeks and looks to go there again soon...definitely not the firehouse +EPO pattern that blowtorches the whole country during some Ninas.

The problem for you guys is that you need a big +PNA with -EPO to deliver the cold, and that hasn't really happened.

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Phil can you explain that chart for us? Or Scott? I don't pay much attention to this stuff but it looks important and I'm sure others would learn from it too.

Every time I see MJO I think of mojo from austin powers. Someone definitely has stolen this winters mojo.

sure.

that's the euro seasonals take on the mjo (a lot of other guidance out there is in a similar camp to that overall look but don't go out as far so don't do that dreaded loop-da-loop).

so basically each of those 8 sections represent a geographical region in the far western pacific/indian ocean/african continent area. you can kind of think of the mjo as this sort of ongoing, propagating region of enhanced convection that originates in the indian ocean region and then shifts eastward from there....sort of pulsing eastward and then starting over again. so these large concentrated areas of convection release large amounts of latent heat and have a large effect on the speed and configuration of the polar jet over the western - and therefore remainder of - pacific ocean. it's an ongoing phenomenon that is stronger in some years, almost absent in others...but generally always doing it's thing year-round...if that makes senses.

anyway, certain "phases" of the mjo generally result in a particular look to the jet, which can help determine downstream conditions. so in DJF, phases 4, 5 and 6 have a significant correlation to above normal temperatures in the eastern half of the united states - mainly due to how that region of convection in the Indonesia-ish region shapes the downstream longwave pattern.

it's not all perfect...some months and some phases have stronger correlations than others. the strength of the pulse matters, other global configurations matter etc.

i think we're looking to the MJO to see if we can get something to shake up the current look - ideally we get a good pulse into phase 8-2...historically more cold/snowy in the East.

anyhow, that diagram showing the pulse waning and then moving back into phase 4 would be bad. :lol:

that's a crude interpretation but good enough i hope.

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Phil can you explain that chart for us?  Or Scott?  I don't pay much attention to this stuff but it looks important and I'm sure others would learn from it too.

Every time I see MJO I think of mojo from austin powers.  Someone definitely has stolen this winters mojo.

Well it's not easy, but I'll try to break it down in a simple manner. The MJO is a wave that propoates around the Earth. This wave though, sometimes will not propagate if ENSO dictates and I'll explain why. The wave is a couplet where we have enhanced low level convergence and enhanced divergence aloft. The wave is found along the tropical regions near the equator and enhanced convection is a result of whereever this wave lies. In a case like what we have now where the La Nina is very formidable and does not show signs of weakening..the convection typcially hangs out around the Indian Ocean and Indoneasia area. In this area, we have strong convergence from the easterly wind anomalies found at lower levels. This is exactly what s happening right now. With convection you get latent heat release. This latent heat release is known to help build ridging downstream. So with that, it makes sense that certain areas of the globe where the wave is found will ultimately have a say as to whether parts of the  US are warm or cold. During this time of year when the MJO wave is found in phase 4, it typically means troughing in the west and ridging in the east. Typical La Nina state. When the wave goes from phase 4 to phase 6 and then phase 8, it is heading east. Phase 8 and phase 1 and  are from near the date line and points east. So convection downwind of the area near and just east of thwe dateline will typically be an area where we find ridging. This is when we can get a classic +PNA. Now the grapsh also shows amplitude. A wave closer to the circle in the middle tends to be extremely weak. A wave found further away from the circle and closer to the perimeter of the graph tends to be much stronger. Amplitude of the wave is obviously important as the stronger a wave is...the stronger the forcing it has associated with it. In the graph Phil posted, it shows the wave moving along towards phase 7...a phase better than what we have now, but we've seen it before and it didn't materialize. It's also important not to get caught up with this. The MJO is one of many factors and sometimes does not influence the pattern locally, at all. Also, MJO forecasts are notoriously bad in the long range. It's just another piece of guidance.

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Phil can you explain that chart for us? Or Scott? I don't pay much attention to this stuff but it looks important and I'm sure others would learn from it too.

Every time I see MJO I think of mojo from austin powers. Someone definitely has stolen this winters mojo.

LOL...I was thinking the same thing. I kept cracking up because they didn't have such things when I went to met school and I kept thinking about loosing my mojo!

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Well it's not easy, but I'll try to break it down in a simple manner. The MJO is a wave that propoates around the Earth. This wave though, sometimes will not propagate if ENSO dictates and I'll explain why. The wave is a couplet where we have enhanced low level convergence and enhanced divergence aloft. The wave is found along the tropical regions near the equator and enhanced convection is a result of whereever this wave lies. In a case like what we have now where the La Nina is very formidable and does not show signs of weakening..the convection typcially hangs out around the Indian Ocean and Indoneasia area. In this area, we have strong convergence from the easterly wind anomalies found at lower levels. This is exactly what s happening right now. With convection you get latent heat release. This latent heat release is known to help build ridging downstream. So with that, it makes sense that certain areas of the globe where the wave is found will ultimately have a say as to whether parts of the US are warm or cold. During this time of year when the MJO wave is found in phase 4, it typically means troughing in the west and ridging in the east. Typical La Nina state. When the wave goes from phase 4 to phase 6 and then phase 8, it is heading east. Phase 8 and phase 1 and are from near the date line and points east. So convection downwind of the area near and just east of thwe dateline will typically be an area where we find ridging. This is when we can get a classic +PNA. Now the grapsh also shows amplitude. A wave closer to the circle in the middle tends to be extremely weak. A wave found further away from the circle and closer to the perimeter of the graph tends to be much stronger. Amplitude of the wave is obviously important as the stronger a wave is...the stronger the forcing it has associated with it. In the graph Phil posted, it shows the wave moving along towards phase 7...a phase better than what we have now, but we've seen it before and it didn't materialize. It's also important not to get caught up with this. The MJO is one of many factors and sometimes does not influence the pattern locally, at all. Also, MJO forecasts are notoriously bad in the long range. It's just another piece of guidance.

i guess i wasn't really pointing at the end of that run...more the move to the COD and then return to 4.

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Well it's not easy, but I'll try to break it down in a simple manner. The MJO is a wave that propoates around the Earth. This wave though, sometimes will not propagate if ENSO dictates and I'll explain why. The wave is a couplet where we have enhanced low level convergence and enhanced divergence aloft. The wave is found along the tropical regions near the equator and enhanced convection is a result of whereever this wave lies. In a case like what we have now where the La Nina is very formidable and does not show signs of weakening..the convection typcially hangs out around the Indian Ocean and Indoneasia area. In this area, we have strong convergence from the easterly wind anomalies found at lower levels. This is exactly what s happening right now. With convection you get latent heat release. This latent heat release is known to help build ridging downstream. So with that, it makes sense that certain areas of the globe where the wave is found will ultimately have a say as to whether parts of the US are warm or cold. During this time of year when the MJO wave is found in phase 4, it typically means troughing in the west and ridging in the east. Typical La Nina state. When the wave goes from phase 4 to phase 6 and then phase 8, it is heading east. Phase 8 and phase 1 and are from near the date line and points east. So convection downwind of the area near and just east of thwe dateline will typically be an area where we find ridging. This is when we can get a classic +PNA. Now the grapsh also shows amplitude. A wave closer to the circle in the middle tends to be extremely weak. A wave found further away from the circle and closer to the perimeter of the graph tends to be much stronger. Amplitude of the wave is obviously important as the stronger a wave is...the stronger the forcing it has associated with it. In the graph Phil posted, it shows the wave moving along towards phase 7...a phase better than what we have now, but we've seen it before and it didn't materialize. It's also important not to get caught up with this. The MJO is one of many factors and sometimes does not influence the pattern locally, at all. Also, MJO forecasts are notoriously bad in the long range. It's just another piece of guidance.

Makes sense. I always thought that as a result of divergence in the upper equatorial troposphere in the vicinity of the convection, you have enhanced upper level equatorial westerlies out ahead of the convective wave and suppressed (and even reversed) westerlies in its wake. This, in turn, induces an upper level cyclonic circulation to the northeast and southeast of the wave, and upper level anti-cyclonic circulation to the northwest and southwest of the wave. I'm not quite sure exactly how far ahead and behind the wave these induced gyres occur or how phase 4 or 5 teleconnects to a -PNA. This page does a better job explaining basic MJO dynamics: http://www-das.uwyo.edu/~geerts/cwx/notes/chap12/mjo.html

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Thanks guys great stuff.

The circle of death...is that geographic or representative of something on the charts?

The circle represents the different geographic regions of the MJO phases. The current location of the wave is where the most recent dot on the chart is. For instance, on Dec. 8th the convective wave is located in the middle of phase 5, which is in extreme W Pacific, Maritime Continent (SE Asia) region.

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Middle of next week could be pretty cool...maybe ern areas? High builds in and we have cold air advection from Maine. Maybe some OE sprinkles or flurries.

Outside chance of a sprinkle or flurry along the south coast an the cape? man this pattern blows cant believe im even asking

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