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Medium-long range thread


tombo82685

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I think we're having an apple and orange discussion while we are posting about a change in the pattern to sustained cold he may be posting about another transient shot of cold air making it into the northeast. One of Walt's favorite (he has alot) charts still doesn't show much before Christmas.

naefs ftw

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Yes less of a factor, but also not a driving force for a pattern change either. I have found about a two week lag works ok for us for a pattern change when the mjo crosses from p5 to p6. This is predicated on it remaining active into the colder phases. There were some excellent points made by Adam a couple of pages back on the MJO.

Don't know if you have ever seen this, but this not only shows the warm/cold phases but gives the statistical significance for those phases throughout the Conus.

post-623-0-85057300-1323629203.png

If understand statistical significance correctly, does that mean phases 5-6 have a small affect on the NE?

Keep in mind, that it is the MJO ONLY. There are other types of convection (e.g. Kelvin waves, mixed Rossby-gravity waves, etc) that project onto the "MJO" phase space. Now again,I'm not totally on board with the Roundy forecast, but here is the total tropical convection around the phase space... it's also not accurate because it doesn't do a good job of forecasting other types of convection until about 5-7 day window (like anything else), but note that it is very accurate in hindsight...

So, what to take away from all of this? The Roundy algorithm does a good job of breaking tropical convection into its component pieces and that its MJO forecast is ok, but a little slow (in this case).

Essentially the Roundy is just the tropical forcing only, correct? Are we to incorporate both the MJO phase space diagrams and the Roundy together and blend them?

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If understand statistical significance correctly, does that mean phases 5-6 have a small affect on the NE?

Essentially the Roundy is just the tropical forcing only, correct? Are we to incorporate both the MJO phase space diagrams and the Roundy together and blend them?

Its actually the opposite. Its about a 95% confidence interval. From that link:

  • Right 8 panels: Displayed as in the left panel except showing the level of statistical significance. Purple/blue shaded areas (lower percentages) represent regions that have higher levels of statistical significance according to a Monte Carlo test (see details in methodology). In these plots, a significance level of 5% means that there is a 5% chance that the anomalies arise from random chance (also known as the 95% confidence level).

As for the second I believe you are right, its just the convection. See if Adam posts tomorrow to make sure.

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Its actually the opposite. Its about a 95% confidence interval. From that link:

  • Right 8 panels: Displayed as in the left panel except showing the level of statistical significance. Purple/blue shaded areas (lower percentages) represent regions that have higher levels of statistical significance according to a Monte Carlo test (see details in methodology). In these plots, a significance level of 5% means that there is a 5% chance that the anomalies arise from random chance (also known as the 95% confidence level).

As for the second I believe you are right, its just the convection. See if Adam posts tomorrow to make sure.

So phases 7, 1, and 2 are the ones where the MJO may have a less affect for our region and or there are other factors that contribute to temperature anomalies when the MJO is in that phase?

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So phases 7, 1, and 2 are the ones where the MJO may have a less affect for our region and or there are other factors that contribute to temperature anomalies when the MJO is in that phase?

from my understanding, phases 7 8 and 1 are all good for us. I believe you have to go back to the date line in the pacific to see the results downstream. Convection fires near the dateline(where the MJO helps enhance convection with its wave prop) latent heat, favors -epo yada yada... im no expert.

But each phase, if the wave has enough magnitude, affects us some how,some way. whether 3-6 help enhance the SE ridge (like it has been doing)... the only way the MJO does not HELP* dictate the pattern or drive it, is when it enters the COD. Then you rely on other factors to drive the pattern ie(mountain torque events, ssw, etc...) Hope this helps you.

FYI, phases 7 8 1 were all involved in the winter of 09-10.

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We need to somehow get rid of that se ridge. Otherwise it's a roll over transient -EPO ridge. This in turn leads to a cold shot from a positively tilted trough aligned sw-ne...which isn't a good delivery. Fast PAC flow behind roll over ridge causes this shot to be short lived and also bounces out of here pretty dam quick thanks to the se ridge. Rinse and repeat.

EC ensembles do try and build some slight ridging in NW Canada, but it's got work to do against that se ridge.

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adam, i got a question on the roundy mjo, or whoever can answer...the thick red lines is the mjo, but how do you know what phase its in? Since its like a huge bubble that encompasses multiple phases... Also, whats the difference between the dashed lines and solid lines for the mjo? is that indicative of the cod, or weaker forcing?

2011.png

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We need to somehow get rid of that se ridge. Otherwise it's a roll over transient -EPO ridge. This in turn leads to a cold shot from a positively tilted trough aligned sw-ne...which isn't a good delivery. Fast PAC flow behind roll over ridge causes this shot to be short lived and also bounces out of here pretty dam quick thanks to the se ridge. Rinse and repeat.

EC ensembles do try and build some slight ridging in NW Canada, but it's got work to do against that se ridge.

the ens do have a better look than the previous ones (going off the 10 day one, since thats all i can see). I just don't see how a -epo helps us out in terms of getting snow without any blocking. Sure the epo dumps cold into canada instead of alaska, and into the conus, but everything is so transient. It needs to be timed right with a storm, or its just a cold wave in, cold out, then rain... their is nothing blocking the cold from moving out. Im just extropolating after day ten, havent seen days 11-15, but it looks like that cold shot would be transient and afterwards zonal flow takes over. The nao, looks bad with the pv centered right on the baffin island region, which doesnt bode well for philly on south which depend on west based -nao's. Its nice to see the pv settle further south, but its to far north to help this region, but nne it would get the job done.

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the ens do have a better look than the previous ones (going off the 10 day one, since thats all i can see). I just don't see how a -epo helps us out in terms of getting snow without any blocking. Sure the epo dumps cold into canada instead of alaska, and into the conus, but everything is so transient. It needs to be timed right with a storm, or its just a cold wave in, cold out, then rain... their is nothing blocking the cold from moving out. Im just extropolating after day ten, havent seen days 11-15, but it looks like that cold shot would be transient and afterwards zonal flow takes over. The nao, looks bad with the pv centered right on the baffin island region, which doesnt bode well for philly on south which depend on west based -nao's. Its nice to see the pv settle further south, but its to far north to help this region, but nne it would get the job done.

Isnt the EPO trending positive? http://raleighwx.americanwx.com/models/12zEPOcomparison.html

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So phases 7, 1, and 2 are the ones where the MJO may have a less affect for our region and or there are other factors that contribute to temperature anomalies when the MJO is in that phase?

Yup. It is a rolling three month average (I posted NDJ) they are keeping, so as seasons/wavelengths change, different phases will have different influences (and confidence intervals) depending on the time of year.

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We need to somehow get rid of that se ridge. Otherwise it's a roll over transient -EPO ridge. This in turn leads to a cold shot from a positively tilted trough aligned sw-ne...which isn't a good delivery. Fast PAC flow behind roll over ridge causes this shot to be short lived and also bounces out of here pretty dam quick thanks to the se ridge. Rinse and repeat.

EC ensembles do try and build some slight ridging in NW Canada, but it's got work to do against that se ridge.

If you were describing this scenario and then ask me to guess at the strength of the nina, my first

wouldn't have been weak borderline moderate. NAO no help either.

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the ens do have a better look than the previous ones (going off the 10 day one, since thats all i can see). I just don't see how a -epo helps us out in terms of getting snow without any blocking. Sure the epo dumps cold into canada instead of alaska, and into the conus, but everything is so transient. It needs to be timed right with a storm, or its just a cold wave in, cold out, then rain... their is nothing blocking the cold from moving out. Im just extropolating after day ten, havent seen days 11-15, but it looks like that cold shot would be transient and afterwards zonal flow takes over. The nao, looks bad with the pv centered right on the baffin island region, which doesnt bode well for philly on south which depend on west based -nao's. Its nice to see the pv settle further south, but its to far north to help this region, but nne it would get the job done.

93-94 was a winter that featured -epo/+nao set-ups, and the snow gradient was tremendous. ABE snowiest season on record, meanwhile we had ice storm after stinkin ice storm after stinkin ice storm.

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93-94 was a winter that featured -epo/+nao set-ups, and the snow gradient was tremendous. ABE snowiest season on record, meanwhile we had ice storm after stinkin ice storm after stinkin ice storm.

^ In 1995, we had a icestorm with graciers 2 feet thick, it destroyed a lot of property and our gazebo by the water which was made out of steel. Hope to not see that again.

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To be honest I am not sure how any one can be depending on the ECM or even talking about how it lost the cold look etc when it does this kind of change in a 12 hr period...

post-105-0-19749800-1323649906.gif

For 7.5 and 8 days out in winter this is pretty decent consistency in the model...and the last two runs show a relatively cool look next Sunday.

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93-94 was a winter that featured -epo/+nao set-ups, and the snow gradient was tremendous. ABE snowiest season on record, meanwhile we had ice storm after stinkin ice storm after stinkin ice storm.

Hey Tony - how bout the gradient within the city limits that season, 23" at PHL to 42" in Roxborough, at the most 15 miles as the crow flies.

I was working construction at that time & we had a job in Quakertown that Jan, most nauseating 2 wks of my life driving from our ice to some really serious snow up that way.

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post-105-0-19749800-1323649906.gif

For 7.5 and 8 days out in winter this is pretty decent consistency in the model...and the last two runs show a relatively cool look next Sunday.

Yeah, every once in a while the OP is going to have an inconsistent run,especially that far out. That doesn't mean you should disregard it because of one run. I'm not sure what he's getting at.

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Hey Tony - how bout the gradient within the city limits that season, 23" at PHL to 42" in Roxborough, at the most 15 miles as the crow flies.

I was working construction at that time & we had a job in Quakertown that Jan, most nauseating 2 wks of my life driving from our ice to some really serious snow up that way.

Yeah that was one winter for the books.

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Yeah, every once in a while the OP is going to have an inconsistent run,especially that far out. That doesn't mean you should disregard it because of one run. I'm not sure what he's getting at.

The images he posted were from different model runs that I posted which were only 12 hrs apart..(the runs of the ECM model) ..

It was a clear 360 degree spin at the 7 day range and that is what i was getting at..

One model run has warm air and a pig ridge on the east coast..Next model run there is a trough along the east coast and warmer air to the west...

Inconsistency is the point..and if a model is inconsistent you can not just "look" at an operational run and because it shows a "pig ridge" assume that is the way its going to result and that is the problem with a lot of the negativity is because they see that and think doom and gloom but when you turn to the ensemble means of that same model you see a flatter SE ridge and a colder look and that colder look in the ensemble means (and yes its smoothed down but the ECM means are higher resolution then say the GFS means) lines up with the rest of the ensemble mean guidance....

Ensemble means should be what is focused on in the medium to the long range and not the operational runs because they will flip like a fish on dry land!

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post-105-0-84152300-1323683129.gif

The "inconsistent" Euro...0z last night on the left, 12z on the right (unfortunately I don't have the 0z Saturday night run available at 500 but the surface depiction is in my post).

Heights have nudged a bit higher at day 7 but the relevant pattern is pretty damn similar.

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I know you guys are stressed about the warmth... I'm dying out here from the dryness. No measureable precip for over 3 weeks. That's normal... in summer. Its unusual this time of year. But might as well continue since in less than a week I'll be back east anyway... to enjoy the bath water known as December 2011 ;)

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