BristowWx Posted January 6, 2012 Share Posted January 6, 2012 I hope the 18Z gfs position of the ridge ends up being wrong because it would have people asking "what pattern change." It will likely be right because that is our fate this year it seems... negative PNA will cause the SE ridge to spike...without neg NAO to counter balance things we end up with heat bulging north...I have learned much from this board...January will not turn out well I fear Link to comment Share on other sites More sharing options...
Ji Posted January 6, 2012 Share Posted January 6, 2012 the 18z gfs run is probably the worst run of the year..wall to wall warmth and all the cold air no where near us Link to comment Share on other sites More sharing options...
CooL Posted January 7, 2012 Share Posted January 7, 2012 This was an awesome read Why is a negative NAO (ridging near Greenland) historically good for snow from DC-Boston? And why is a west based NAO notoriously better for snow than an east based NAO? i know the basics but would appreciate a more in depth answer Link to comment Share on other sites More sharing options...
mappy Posted January 7, 2012 Share Posted January 7, 2012 Great article, wes! Link to comment Share on other sites More sharing options...
BristowWx Posted January 7, 2012 Share Posted January 7, 2012 the 18z gfs run is probably the worst run of the year..wall to wall warmth and all the cold air no where near us I'd be curious to see how Henry or Joe would spin this run...a fluke? 00z will be telling Link to comment Share on other sites More sharing options...
usedtobe Posted January 7, 2012 Author Share Posted January 7, 2012 This was an awesome read Why is a negative NAO (ridging near Greenland) historically good for snow from DC-Boston? And why is a west based NAO notoriously better for snow than an east based NAO? i know the basics but would appreciate a more in depth answer Having blocking over Greenland and Baffin Island often helps hold low pressure near 50n and 50 west. To the west of that upper low the flow is confluent which promotes surface pressure rises over New england which in turn then prmotes low level cold advection and damming. The blocking also help force low pressure systems to our south because of the building pressures to our north. Link to comment Share on other sites More sharing options...
Ian Posted January 7, 2012 Share Posted January 7, 2012 the 18z gfs run is probably the worst run of the year..wall to wall warmth and all the cold air no where near us next... i mean next winter Link to comment Share on other sites More sharing options...
packbacker Posted January 7, 2012 Share Posted January 7, 2012 This was an awesome read Why is a negative NAO (ridging near Greenland) historically good for snow from DC-Boston? And why is a west based NAO notoriously better for snow than an east based NAO? i know the basics but would appreciate a more in depth answer Someone posted this in our forum the other day, thought it was good read.... http://nc-climate.ncsu.edu/climate/patterns/NAO.html Link to comment Share on other sites More sharing options...
Bob Chill Posted January 7, 2012 Share Posted January 7, 2012 the 18z gfs run is probably the worst run of the year..wall to wall warmth and all the cold air no where near us I'm surprised you aren't mentioning hr 156. Move the trough axis 75 miles east and let the lp bomb off of the tidewater... Link to comment Share on other sites More sharing options...
CooL Posted January 7, 2012 Share Posted January 7, 2012 Having blocking over Greenland and Baffin Island often helps hold low pressure near 50n and 50 west. To the west of that upper low the flow is confluent which promotes surface pressure rises over New england which in turn then prmotes low level cold advection and damming. The blocking also help force low pressure systems to our south because of the building pressures to our north. Someone posted this in our forum the other day, thought it was good read.... http://nc-climate.nc...tterns/NAO.html awesome stuff! Thanks guys Link to comment Share on other sites More sharing options...
usedtobe Posted January 7, 2012 Author Share Posted January 7, 2012 Wes, do you hide behind model runs with your "honest" thoughts on the pattern, or am I just paranoid? Mitch, my honest opinion was in the article. I could see the negative PNA screwing us but the orientation of the ridge and exact location are far from certain so the 18Z gfs doesn't change anything. I still think this pattern is a little better than what we've had but still is not a good one. Give me a negative Nao with blocking across Greenland into the Baffin bay area and I'd change my tune. Link to comment Share on other sites More sharing options...
CoastalWx Posted January 7, 2012 Share Posted January 7, 2012 Mitch, my honest opinion was in the article. I could see the negative PNA screwing us but the orientation of the ridge and exact location are far from certain so the 18Z gfs doesn't change anything. I still think this pattern is a little better than what we've had but still is not a good one. Give me a negative Nao with blocking across Greenland into the Baffin bay area and I'd change my tune. I know this type of pattern is better for up here, but even I wouldn't mind seeing that. Will and I were discussing that it's not the most ideal pattern by any means, but it could still produce if the EC was close to reality. If some of the key parts are shifted or weakened....then the risk is liquid. The EC ensembles did have an overrunning look for you guys around d11-13, but the se ridge built up a little towards the end of the run. Link to comment Share on other sites More sharing options...
CoastalWx Posted January 7, 2012 Share Posted January 7, 2012 If anything, the latest and greatest term, SSW, could be a nice learning tool one way or another. Some people as we know have gotten excited about it bring the day after tomorrow scenario, but if nothing else..it could be a good learning experience, regarding how this warming behaves. At least that's how I'm looking at it. Link to comment Share on other sites More sharing options...
mitchnick Posted January 7, 2012 Share Posted January 7, 2012 If anything, the latest and greatest term, SSW, could be a nice learning tool one way or another. Some people as we know have gotten excited about it bring the day after tomorrow scenario, but if nothing else..it could be a good learning experience, regarding how this warming behaves. At least that's how I'm looking at it. learning experiences when it snows are great learning experiences because it doesn't plain suk Link to comment Share on other sites More sharing options...
CoastalWx Posted January 7, 2012 Share Posted January 7, 2012 learning experiences when it snows are great learning experiences because it doesn't plain suk LOL, well for me...either one are interesting. We'll just have to see how this plays out. Link to comment Share on other sites More sharing options...
usedtobe Posted January 7, 2012 Author Share Posted January 7, 2012 If anything, the latest and greatest term, SSW, could be a nice learning tool one way or another. Some people as we know have gotten excited about it bring the day after tomorrow scenario, but if nothing else..it could be a good learning experience, regarding how this warming behaves. At least that's how I'm looking at it. It should be a learning experience. I do believe in strong and weak vortex events and that they can be used at times to make a long range forecast but think that ssw events have gotten sexy and are overused. It's usually smart to play pattern changes conservatively or you'll end up like JB often does. Link to comment Share on other sites More sharing options...
H2O Posted January 7, 2012 Share Posted January 7, 2012 I like the article a lot, Wes. I'm glad to read some of the nuts and bolts. This is good stuff. Link to comment Share on other sites More sharing options...
RodneyS Posted January 7, 2012 Share Posted January 7, 2012 It is a good article but to be honest the general public probably might get lost reading that. I thought it did a good job of balancing the technical with the non-technical. The maps showing the consecutive 11-15 day forecasts from the GFS model were particularly instructive for the layman, as they illustrate the significant uncertainties of forecasting that far out. Link to comment Share on other sites More sharing options...
Kevin Druff Posted January 7, 2012 Share Posted January 7, 2012 It should be a learning experience. I do believe in strong and weak vortex events and that they can be used at times to make a long range forecast but think that ssw events have gotten sexy and are overused. It's usually smart to play pattern changes conservatively or you'll end up like JB often does. Wes and others who've been around a while: Can someone give me a handle on how good some of these long-term outlooks are? I'm thinking of Euro Weeklies, CFS, and, to a lesser extent, analog methods such as Don Sutherland's discussing over in the main forum, etc. I realize the weather will do what it will do. But, are the computer models to a certain extent weighted towards the status quo continuing until they're smacked over the head with pattern changes? That's kind of a vague set of questions that there aren't good answers to, I'm mostly looking for opinions here, I guess.... Link to comment Share on other sites More sharing options...
usedtobe Posted January 7, 2012 Author Share Posted January 7, 2012 Wes and others who've been around a while: Can someone give me a handle on how good some of these long-term outlooks are? I'm thinking of Euro Weeklies, CFS, and, to a lesser extent, analog methods such as Don Sutherland's discussing over in the main forum, etc. I realize the weather will do what it will do. But, are the computer models to a certain extent weighted towards the status quo continuing until they're smacked over the head with pattern changes? That's kind of a vague set of questions that there aren't good answers to, I'm mostly looking for opinions here, I guess.... Kevin, the computers models (euro weeklies, CFS) do not weigh the status quo. They are based on the physical equations that govern the atmosphere and/or approximations of those physical processes (for example convection). They may have biases for example this winter the GEFS ensemble forecasts of the NAO has been too low most of the winter. Don bases much of his forecasts on the typical climo patterns associated with ENSO and his feelings about what will happen to the AO and NAO based again I think on how they have acted in the past. You'd have to ask Don for more in depth discussion. He seems to do pretty well with his techniques. Link to comment Share on other sites More sharing options...
Kevin Druff Posted January 7, 2012 Share Posted January 7, 2012 Kevin, the computers models (euro weeklies, CFS) do not weigh the status quo. They are based on the physical equations that govern the atmosphere and/or approximations of those physical processes (for example convection). They may have biases for example this winter the GEFS ensemble forecasts of the NAO has been too low most of the winter. Yes, as a programmer, I understand that the computer only does the math it's told to do. I guess I was too specific with directing my question at the process of solving the equation. We can't measure every point on earth with 100% accuracy, we don't have the computing power to model at that resolution, and we don't understand all of the drivers of weather and how individual micro elements (whether it's solar, lunar, the rest of the cosmos, butterflies, convection, etc.) influence the macro. Because of this, the equations we ask the computer to solve will nearly always give us an incorrect result. At shorter time frames, the error is acceptable. As time increases the error becomes more and more relevant and acute. Srain hit on what I was interested in this morning over on the main thread: What often happen when a whole sale pattern change occurs are guidance flip flops and various solutions will change like the hands on a clock. 1) is this true? 2) because we're reasonably accurate in the short term, and, I would argue, the short-term is pretty heavily biased to the status quo, are the equations we ask the computer to solve more likely to result in a pattern that resembles the short-term? I'm still learning and trying to grok meteorology. As such, maybe my thoughts are a little off the wall and totally inaccurate. I welcome corrections and links to further reading. Link to comment Share on other sites More sharing options...
usedtobe Posted January 7, 2012 Author Share Posted January 7, 2012 Yes, as a programmer, I understand that the computer only does the math it's told to do. I guess I was too specific with directing my question at the process of solving the equation. We can't measure every point on earth with 100% accuracy, we don't have the computing power to model at that resolution, and we don't understand all of the drivers of weather and how individual micro elements (whether it's solar, lunar, the rest of the cosmos, butterflies, convection, etc.) influence the macro. Because of this, the equations we ask the computer to solve will nearly always give us an incorrect result. At shorter time frames, the error is acceptable. As time increases the error becomes more and more relevant and acute. Srain hit on what I was interested in this morning over on the main thread: 1) is this true? 2) because we're reasonably accurate in the short term, and, I would argue, the short-term is pretty heavily biased to the status quo, are the equations we ask the computer to solve more likely to result in a pattern that resembles the short-term? I'm still learning and trying to grok meteorology. As such, maybe my thoughts are a little off the wall and totally inaccurate. I welcome corrections and links to further reading. It's that errors grow non linearly so small errors at the shorter time ranges can lead to bigger ones and much more spread between members as you go out in time. In the longer time ranges, models often flip from run to run as that is just another way to assess the uncertainty of a solution. Even at the shorter time ranges you sometimes see enough differences to change a forecast from snow to rain. Status quo would suggest that the models never predict a storm to deepen rapdily along the coast and they often do in nature and in the model runs. Link to comment Share on other sites More sharing options...
easternsnowman Posted January 7, 2012 Share Posted January 7, 2012 Joe Lundberg is not convinced a pattern change is going to happen: http://www.accuweath...uary-thaw/59946 Joe Lundeberg hates cold and snow and worships the euro weeklies and also is part of accuweather....enough said! Link to comment Share on other sites More sharing options...
dtk Posted January 7, 2012 Share Posted January 7, 2012 It's that errors grow non linearly so small errors at the shorter time ranges can lead to bigger ones and much more spread between members as you go out in time. In the longer time ranges, models often flip from run to run as that is just another way to assess the uncertainty of a solution. Even at the shorter time ranges you sometimes see enough differences to change a forecast from snow to rain. Status quo would suggest that the models never predict a storm to deepen rapdily along the coast and they often do in nature and in the model runs. The one thing that I don't see often discussed is that NWP (from nowcasting to the medium range, say out to 7 days) is predominantly an initial condition problem. However, weekly/seasonal/annual forecasting is generally more-so a boundary value and/or forcing problem (sst/land, seasonal cycle, solar, etc.). Some models do actually have components that relax toward climatology (for example, the GFS, since it is not coupled to an ocean model, relaxes SSTs toward climo with an e-folding of like 6 days or so...). The same is true for the GEFS (since it is also an uncoupled atmospheric model). CFS (v2), on the other hand, is explicitly coupled to an ocean model, which has lead to an increase in skill for things like the MJO. Link to comment Share on other sites More sharing options...
usedtobe Posted January 7, 2012 Author Share Posted January 7, 2012 The one thing that I don't see often discussed is that NWP (from nowcasting to the medium range, say out to 7 days) is predominantly an initial condition problem. However, weekly/seasonal/annual forecasting is generally more-so a boundary value and/or forcing problem (sst/land, seasonal cycle, solar, etc.). Some models do actually have components that relax toward climatology (for example, the GFS, since it is not coupled to an ocean model, relaxes SSTs toward climo with an e-folding of like 6 days or so...). The same is true for the GEFS (since it is also an uncoupled atmospheric model). CFS (v2), on the other hand, is explicitly coupled to an ocean model, which has lead to an increase in skill for things like the MJO. Thanks, that makes sense. IS the euro coupled and euro weekleis based on a coupled model? Link to comment Share on other sites More sharing options...
Kevin Druff Posted January 7, 2012 Share Posted January 7, 2012 It's that errors grow non linearly so small errors at the shorter time ranges can lead to bigger ones and much more spread between members as you go out in time. In the longer time ranges, models often flip from run to run as that is just another way to assess the uncertainty of a solution. Even at the shorter time ranges you sometimes see enough differences to change a forecast from snow to rain. Status quo would suggest that the models never predict a storm to deepen rapdily along the coast and they often do in nature and in the model runs. Thanks, Wes. DTK hit what I was trying to get at in his discussing of SST reverting to climo. Even if we could accurately measure initial conditions for enough points on earth to get a "better" answer, we don't know/understand/model/process all things that affect weather, let alone have them boiled down to the proper physics equation in a computer simulation. This causes bigger problems the farther away from "now" we get. The human brain can utilize its knowledge and experience to tweak an equation and say, "no, I've seen this before" and get a different and more successful result as you mention. A computer can't. It simply does the math we've told it to do. Link to comment Share on other sites More sharing options...
dtk Posted January 7, 2012 Share Posted January 7, 2012 Thanks, that makes sense. IS the euro coupled and euro weekleis based on a coupled model? The ECMWF operational model is only coupled to a wave model (they don't have an interactive ocean). Their weekly/seasonal stuff is more complicated. For example, their EPS is run with forced SST for the first ten days (when they have higher resolution), but then things are truncated and then coupled to an ocean model (NEMO) out to 30+ days. They also have a deterministic run that is fully coupled from the start at lower resolution (at least, I think this is true....and comparable to our CFSv2). Link to comment Share on other sites More sharing options...
usedtobe Posted January 8, 2012 Author Share Posted January 8, 2012 The ECMWF operational model is only coupled to a wave model (they don't have an interactive ocean). Their weekly/seasonal stuff is more complicated. For example, their EPS is run with forced SST for the first ten days (when they have higher resolution), but then things are truncated and then coupled to an ocean model (NEMO) out to 30+ days. They also have a deterministic run that is fully coupled from the start at lower resolution (at least, I think this is true....and comparable to our CFSv2). Thanks, I never see the weeklies but here them discussed by people who subscribe but since some have said the weeklies were showing real warmth for early Feb, I thought I'd ask about them. Link to comment Share on other sites More sharing options...
usedtobe Posted January 8, 2012 Author Share Posted January 8, 2012 Rather than clutter the Jan storm thread with my not always optimistic ideas about the pattern, I thought I'd start keeping them in their own thread. We'll start with last night's 8-10 day comparison of the GSF and euro since the euro negative NAO look has some salivating. It could of course be correct but it has a tendency to overdo blocking so caveat emptor. The one nice thing about both models is they do have cross polar flow which should give us more chilly intrusions than we had in Dec but the lack of snow cover could make them less impressive than the initial forecasts of them. The euro also allows some pacific flow into the u.s. because of the trough just off the Pac NW and with the negative nao look, the pattern would be one that would offer snow chances. It's a pretty good look, that's the good news. Now lets look at why there is reason to view it with skepticism. The Euro ensemble mean for 240 hours has a negative ao but the nao is pretty clearly positive. note the lower than normal heights over Iceland, Greenland and Baffin Bay. It too would suggest impulses would break through from the pacific but the positive NAO would make it harder to get the storms to track to our south with the negative PNA look to the pacific ridge, it's the old negative epo (good) but negative pna (bad). It's not a horrible look but we'd probably waffle between cool shots end end most storms as rain. The gfs ensemble mean for 240 hours also has a positive nao , it's not a warm look but also is not a frigid one and it has the nao even more positive than the euro ens mean. What about the Stratospheric warming event. It certainly reversed the winds at 1 mb but has a ways to go before it reverses the winds at 30 mb. Plus if you look at the EP flux vectors, they start pointing more strongly towards the south (left) towards the end of the period just about the time that the 30 mb zonal wind decrease levels off. We have not had a wind reversal at 30 mb. The warming may have helped with the high heights over the north Pacific that have built locally but this still is not yet the big kahuna. It might end up being that but so far, it isn't. Finally, lets look at the ens mean at the end of the period. No I'm not showing it because I think it is right, it won't be. I am showing it because it starts looking like it wants to take the ao back to positive. That may not happen but it probably does suggest that the AO may not spike high enough to guarantee that the NAO goes to negative and stays there. The change we'd like to see. is not being advertised. Has the pattern changed yes, do we know the full ramifications of the change, no. We probalby will see more shots of cold than we have been seeing most of the winter and may see an overrunning event down the line though right now I don't really see it. I DO not think the Nao is going to go to a sustained negative period. Heck no, it is more likely to remain positive than negative for the forseeable future. Anyway those are my thoughts. I thought I'd keep them out of the cheerleader thread. Link to comment Share on other sites More sharing options...
nw baltimore wx Posted January 8, 2012 Share Posted January 8, 2012 Rather than clutter the Jan storm thread with my no always optimistic ideas about the pattern, I thought I'd start keeping them in their own thread. Anyway those are my thoughts. I thought I'd keep them out of the cheerleader thread. Thanks, Wes. I wish this was a month ago. Like others, I'm worried that the changes we need for a true snowier pattern may come too late this year. The truth may hurt, but keep it coming. Link to comment Share on other sites More sharing options...
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