WinterWxLuvr Posted December 8, 2015 Author Share Posted December 8, 2015 I can never tell when people are serious around here Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 8, 2015 Author Share Posted December 8, 2015 OK, I need a couple of lessons from the big boys. First, what are the GEPS? Second, if only looking at the lower 48, can someone explain why the EPS and GEPS would be bad at day 10. I know it doesn't look "great", but I think we have seen snow in worse patterns than that. Link to comment Share on other sites More sharing options...
T. August Posted December 8, 2015 Share Posted December 8, 2015 lol it wasn't even that good. 12-18" with temps below freezing the entire time? I know it made me smile. I think that's the best modeled storm so far this season. Link to comment Share on other sites More sharing options...
Scarlet Pimpernel Posted December 8, 2015 Share Posted December 8, 2015 OK, I need a couple of lessons from the big boys. First, what are the GEPS? Second, if only looking at the lower 48, can someone explain why the EPS and GEPS would be bad at day 10. I know it doesn't look "great", but I think we have seen snow in worse patterns than that. Not one of the "big boys" here per se...but the GEFS (I assume you meant that, and not GEPS) refers to the Global Ensemble Forecast System. Which is the GFS-based ensemble system (21 members, including the control; the control is the lower resolution version of the deterministic GFS, essentially). As for whether the EPS or GEFS look "bad" or "good", that's open to some interpretation. Typically one would want to look at the ensemble mean flow pattern, which would would give a better idea of things compared to the deterministic GFS (there are reasons for this, a bit complicated...but it's been proven in the literature that use of the ensemble mean in the medium-longer range is better than using the deterministic. I'm greatly simplifying here, I know!). There are many times that the ensemble mean...either the EPS or GEFS or both...might look not so good at the same forecast hour compared to what the deterministic versions look like, or vice-versa. You can sort of think of the deterministic model as a type of "ensemble member" itself, i.e., one solution of many, though at higher resolution than the ensembles as I said earlier. One would also like to see the ensemble member spread of solutions, to get an idea of how well the model system has a handle on the overall flow, e.g., if there's a tight cluster around the mean, then there's more confidence, generally. Or, you could have, say, two solution clusters widely disparate from each other, in which case the mean is not too useful. As you can imagine, that makes interpreting things a lot more difficult (which cluster to go with, etc.)! I know there are others that could better describe this, but hope this is helpful and reasonably accurate at least, as a quick overview! Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 8, 2015 Author Share Posted December 8, 2015 Not one of the "big boys" here per se...but the GEFS (I assume you meant that, and not GEPS) refers to the Global Ensemble Forecast System. Which is the GFS-based ensemble system (21 members, including the control; the control is the lower resolution version of the deterministic GFS, essentially). As for whether the EPS or GEFS look "bad" or "good", that's open to some interpretation. Typically one would want to look at the ensemble mean flow pattern, which would would give a better idea of things compared to the deterministic GFS (there are reasons for this, a bit complicated...but it's been proven in the literature that use of the ensemble mean in the medium-longer range is better than using the deterministic. I'm greatly simplifying here, I know!). There are many times that the ensemble mean...either the EPS or GEFS or both...might look not so good at the same forecast hour compared to what the deterministic versions look like, or vice-versa. You can sort of think of the deterministic model as a type of "ensemble member" itself, i.e., one solution of many, though at higher resolution than the ensembles as I said earlier. One would also like to see the ensemble member spread of solutions, to get an idea of how well the model system has a handle on the overall flow, e.g., if there's a tight cluster around the mean, then there's more confidence, generally. Or, you could have, say, two solution clusters widely disparate from each other, in which case the mean is not too useful. As you can imagine, that makes interpreting things a lot more difficult (which cluster to go with, etc.)! I know there are others that could better describe this, but hope this is helpful and reasonably accurate at least, as a quick overview! No, on TropTB it's GEPS, GEFS, EPS. I don't know what GEPS is. And....I was saying the mean on the two I mentioned didn't look that bad over the lower 48. Link to comment Share on other sites More sharing options...
Bob Chill Posted December 8, 2015 Share Posted December 8, 2015 GEPS on trop tids is the Canadian ens. I tend not to look at it much. D10-13 looks like our first cool shot this month. Most likely transient unless the onslaught of shortwaves pounding the west coast turns into a nice stable ridge. If something actually hits during d10-15 it would be quite a fluke and very low probability Link to comment Share on other sites More sharing options...
Bob Chill Posted December 8, 2015 Share Posted December 8, 2015 As Wes pointed out in the panic thread, the EPS are hideous at the end. However, the now what appears to be a fairly large and cold trough undercutting the higher heights in Canada d10-12 was not even hinted at on the EPS 4 days ago. The end of the EPS runs have consistently shown ugly trough west/ridge east day in day out but at closer ranges things aren't as dire. I will admit that the d15 look on the 12z EPS is one of the worst yet at long range. As Ji said earlier...all the reds and blues are in the wrong places...lol Link to comment Share on other sites More sharing options...
Ian Posted December 8, 2015 Share Posted December 8, 2015 12-18" with temps below freezing the entire time? I know it made me smile. I think that's the best modeled storm so far this season. Highly unlikely it would do that given the 500mb at the time. As noted there would be interest probably followed by failure if it was near term. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 8, 2015 Author Share Posted December 8, 2015 As Wes pointed out in the panic thread, the EPS are hideous at the end. However, the now what appears to be a fairly large and cold trough undercutting the higher heights in Canada d10-12 was not even hinted at on the EPS 4 days ago. The end of the EPS runs have consistently shown ugly trough west/ridge east day in day out but at closer ranges things aren't as dire. I will admit that the d15 look on the 12z EPS is one of the worst yet at long range. As Ji said earlier...all the reds and blues are in the wrong places...lol I guess you only see day 15 on pay site? Link to comment Share on other sites More sharing options...
yoda Posted December 8, 2015 Share Posted December 8, 2015 18z GFS keeps up the decent LR idea... has two decent storm chances near at the end of the run -- all I really care is that its still there... also again hints at the idea of a decent cold blast heading our way as the run ends Link to comment Share on other sites More sharing options...
Bob Chill Posted December 8, 2015 Share Posted December 8, 2015 I guess you only see day 15 on pay site? Euro ens end at d15. Weeklies come out on Mon & Thurs. Link to comment Share on other sites More sharing options...
Bob Chill Posted December 8, 2015 Share Posted December 8, 2015 Let's see how this plays out. Can't really look a whole lot worse than this for us d15. Let's see how the period around the 23rd evolves as we get closer. Link to comment Share on other sites More sharing options...
yoda Posted December 8, 2015 Share Posted December 8, 2015 18z GFS keeps up the decent LR idea... has two decent storm chances near at the end of the run -- all I really care is that its still there... also again hints at the idea of a decent cold blast heading our way as the run ends -28c 850s show up in MT/NW Upper Plains states as the run ends Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 8, 2015 Author Share Posted December 8, 2015 LOL so nobody is gonna talk about the GFS at day 9? Link to comment Share on other sites More sharing options...
BristowWx Posted December 8, 2015 Share Posted December 8, 2015 LOL so nobody is gonna talk about the GFS at day 9? I saw it and pretended I didn't...I've learned this is not the thread to bring up day 9 fantasy snow that will be gone next run... Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 8, 2015 Author Share Posted December 8, 2015 Let's see how this plays out. Can't really look a whole lot worse than this for us d15. Let's see how the period around the 23rd evolves as we get closer. d15puke.JPG I was looking at the 10 day, but my thoughts apply here as well. The heights here look bad by that map but they aren't that high (awful). We can get seasonable air under heights that are 50 meters above normal. And that flow, while not a classic big snow pattern, could still let a weak snow happen. Tell me why I'm wrong. I like to learn this stuff. BTW, the 10 day looked better, IMO. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 8, 2015 Author Share Posted December 8, 2015 I saw it and pretended I didn't...I've learned this is not the thread to bring up day 9 fantasy snow that will be gone next run... I think we should point out positives when they are there. I don't trust the gfs out very far, but I think we are starting to see at least glimmers of hope. Link to comment Share on other sites More sharing options...
Wonderdog Posted December 9, 2015 Share Posted December 9, 2015 As Wes pointed out in the panic thread, the EPS are hideous at the end. However, the now what appears to be a fairly large and cold trough undercutting the higher heights in Canada d10-12 was not even hinted at on the EPS 4 days ago. The end of the EPS runs have consistently shown ugly trough west/ridge east day in day out but at closer ranges things aren't as dire. I will admit that the d15 look on the 12z EPS is one of the worst yet at long range. As Ji said earlier...all the reds and blues are in the wrong places...lol With the change in the EPS in the 10-12 day period (not shown 4 days ago), can we conclude that there may or will be changes in the longer range on the EPS, assuming the undercutting cold trough idea is correct. Link to comment Share on other sites More sharing options...
BristowWx Posted December 9, 2015 Share Posted December 9, 2015 In that case I thought the 500mb pattern at 384 looked kind of decent. I mean that is an east based -NAO and neutral PNA correct? Link to comment Share on other sites More sharing options...
Wonderdog Posted December 9, 2015 Share Posted December 9, 2015 I saw it and pretended I didn't...I've learned this is not the thread to bring up day 9 fantasy snow that will be gone next run... That was hinted at a few days ago on the GFS. I like the fact that it is showing up again. Link to comment Share on other sites More sharing options...
Bob Chill Posted December 9, 2015 Share Posted December 9, 2015 I was looking at the 10 day, but my thoughts apply here as well. The heights here look bad by that map but they aren't that high (awful). We can get seasonable air under heights that are 50 meters above normal. And that flow, while not a classic big snow pattern, could still let a weak snow happen. Tell me why I'm wrong. I like to learn this stuff. BTW, the 10 day looked better, IMO. 15 day means are always smoothed out quite a bit due to spread over time. Unfortunately with the 15 day plot I posted there are prominent low height anomalies in all the regions we want + heights and vice versa. Basically looks like a complete reset to what we are seeing this week. Hard to put any + spin on that plot other than praying it's dead wrong. Link to comment Share on other sites More sharing options...
BristowWx Posted December 9, 2015 Share Posted December 9, 2015 The last three op runs of the GFS have some idea of ridging near Greenland...later on 18z but it pops up...maybe the EPS is wrong. Who knows at least Xmas doesn't look torch-ish like right now...and at least there is some real cold showing up in upper Midwest...trying to find something to grasp Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 9, 2015 Author Share Posted December 9, 2015 15 day means are always smoothed out quite a bit due to spread over time. Unfortunately with the 15 day plot I posted there are prominent low height anomalies in all the regions we want + heights and vice versa. Basically looks like a complete reset to what we are seeing this week. Hard to put any + spin on that plot other than praying it's dead wrong. Hey Bob, give me a little lesson on the EPO. Isn't the negative phase when you have lower than normal heights in Bering Sea/western Aleutians area and higher than normal Alaska/gulf of Alaska? Or do I have that totally screwed up? Link to comment Share on other sites More sharing options...
WxUSAF Posted December 9, 2015 Share Posted December 9, 2015 Hey Bob, give me a little lesson on the EPO. Isn't the negative phase when you have lower than normal heights in Bering Sea/western Aleutians area and higher than normal Alaska/gulf of Alaska? Or do I have that totally screwed up? https://kcstormfront.files.wordpress.com/2013/12/epo3.png Bering straights/eastern Siberia is more of the WPO domain. Alaska/GOA is the EPO domain. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 9, 2015 Author Share Posted December 9, 2015 https://kcstormfront.files.wordpress.com/2013/12/epo3.png Bering straights/eastern Siberia is more of the WPO domain. Alaska/GOA is the EPO domain. Thanks Link to comment Share on other sites More sharing options...
Bob Chill Posted December 9, 2015 Share Posted December 9, 2015 In extremely simplistic and non technical terms for anyone trying to learn what to look for on h5 plots, here's the most basic... What you want to see in nw Canada and eastern AK is a convex kink in the isobars and at the very least "white or a little bit of yellow" indicating normal or above normal heights. Why? Because of 2 very important things. 1) it means the pac jet full of maritime air is aimed at AK and westward and not directly into British Columbia and southward and 2) it means high pressure under the ridge can easily build big cold air masses in western Canada that dump into the plains and eventually here. It's also an important pattern for cross polar flow (especially in the absence of blocking). If we aren't going to get help with that type of ridge we better have blocking or we're literally toast. When we have no blocking and no help from the -epo height pattern we will struggle very badly for air masses cold enough for frozen precip. Link to comment Share on other sites More sharing options...
BristowWx Posted December 9, 2015 Share Posted December 9, 2015 In extremely simplistic and non technical terms for anyone trying to learn what to look for on h5 plots, here's the most basic... What you want to see in nw Canada and eastern AK is a convex kink in the isobars and at the very least "white or a little bit of yellow" indicating normal or above normal heights. Why? Because of 2 very important things. 1) it means the pac jet full of maritime air is aimed at AK and westward and not directly into British Columbia and southward and 2) it means high pressure under the ridge can easily build big cold air masses in western Canada that dump into the plains and eventually here. It's also an important pattern for cross polar flow (especially in the absence of blocking). If we aren't going to get help with that type of ridge we better have blocking or we're literally toast. When we have no blocking and no help from the -epo height pattern we will struggle very badly for air masses cold enough for frozen precip. So is the 384 hr h5 plot on the Op GFS 18z something decent? All caveats apply and I know it won't look like that later. I mean that looks like something I would think is good. Link to comment Share on other sites More sharing options...
BristowWx Posted December 9, 2015 Share Posted December 9, 2015 Agree on all points. Where that goes from that point would be the question but it won't look like that in three hours anyway. I just wanted to make sure I was on the right track mentally. Many thanks. . Link to comment Share on other sites More sharing options...
BristowWx Posted December 9, 2015 Share Posted December 9, 2015 Yes it's horrible which is why I chose to just focus on the op. A weenie at heart. that screams same old pattern with partly sunny and a high of 53 on Xmas. If that is to be, then so be it. I will just pour a little more Jack in my coffee. After this weekend I might need therapy. Going to reserve a suite in the panic room. Link to comment Share on other sites More sharing options...
stormtracker Posted December 9, 2015 Share Posted December 9, 2015 LOL so nobody is gonna talk about the GFS at day 9? In about 15 minutes, you'll understand why Link to comment Share on other sites More sharing options...
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