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January Med/Long Range Disco Part 2


WinterWxLuvr

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956 bomb but just east enough for nobody along the coast to enjoy a good raking. Heh

Euro weeklies were crushing the area just offshore in that period. :P

 

Close enough. May just have to wait our turn too. Some appetizers first would be ok.

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The good news? The GFS has a strong shortwave down south. 

 

Bad news? There is a pesky ULL over the Lakes from a lobe that breaks off, makes it so HP can't build in that area, 

 

The ironic news? That lobe could form another 50/50 @ 192 hours and there is energy coming in from the West. lol

 

I hadn't paid that much attention the past day or so, especially since this thread went downhill in a hurry for awhile there yesterday from what I saw!

 

But now that I've looked more carefully at the last GFS (or last few runs), I see exactly what you're talking about in terms of that ULL "lobe".  It does indeed screw things up royally for us.  Not sure how long that's been appearing, if it's new or not, but I don't recall really seeing that prior to this weekend.  Also, it's almost as if the blocking, or higher heights, push too far to the west, kind of allowing the "main" vortex to move into a position that's too far northeast (away from the favorable 50/50 position).  Thus, with both of these, the mid-levels are a disaster.

 

Your "ironic" news may be kind of interesting, actually, if that happens!

 

So many things going on, yet to be worked out.  However, I don't like seeing this trend toward a GL low or at least something inhibiting a cold high from pushing down.

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Can someone interpret the previous image of the 0z EPS I just posted?

It seems that the mean is west of the OP meaning there are either more members who have a low closer to the coast or the ones that are closer to the coast are stronger (or both).

Best EPS run of the winter in terms of snowfall means - 4" for DC through D15. I need to dig into the individual members for our various threat periods.

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Best EPS run of the winter in terms of snowfall means - 4" for DC through D15. I need to dig into the individual members for our various threat periods.

 

That's actually up from what Bob Chill mentioned the mean was the other day (I think he said it was 3" at that time?).  At least a potential good sign there.

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I don't have time to worry about every op run every 6 hours when a storm is in fantasy land but I look at the 3 main ensembles(gefs, ggem, eps) each cycle to get a general idea. Ggem given less weight of course but it can sometimes help split a tie between the gefs and eps. Last night was a mixed bag. Gefs definitely took a step in the wrong direction. Still has what looks like a good window in the 6-9 day range but more of the members either cut, stay squashed, or a combo of both. Bad trend of taking something to our north and south showing up. It's a mess overall and mean snow ticked down quite a bit. In the long range gefs still isn't awful but kinda meh. Ggem and eps are more optimistic about the long range. They imply several windows. The first day 6-9 is convoluted by several vorts in the trough. We don't really want one to get all the energy as that probably winds up too much and cuts but at the same time if the app split equally maybe nothing comes together. The EPS shows another 2 good looks around day 11-13 and again day 15. Mean snowfall in eps increased to 4" for Dca and was the best run so far but that is kinda spread out over the 3 windows. So not an awful run but didn't help provide more confidence in anything either.

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It seems that the mean is west of the OP meaning there are either more members who have a low closer to the coast or the ones that are closer to the coast are stronger (or both).

Best EPS run of the winter in terms of snowfall means - 4" for DC through D15. I need to dig into the individual members for our various threat periods.

I saw that, it's a good sign but that 4-5" eps has in our area is spread out across several threats so they aren't loving any one idea it indicate we have several shots.
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It seems that the mean is west of the OP meaning there are either more members who have a low closer to the coast or the ones that are closer to the coast are stronger (or both).

Best EPS run of the winter in terms of snowfall means - 4" for DC through D15. I need to dig into the individual members for our various threat periods.

Thanks and if I may. What does the numbered/color chart refer to?

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I don't have time to worry about every op run every 6 hours when a storm is in fantasy land but I look at the 3 main ensembles(gefs, ggem, eps) each cycle to get a general idea. Ggem given less weight of course but it can sometimes help split a tie between the gefs and eps. Last night was a mixed bag. Gefs definitely took a step in the wrong direction. Still has what looks like a good window in the 6-9 day range but more of the members either cut, stay squashed, or a combo of both. Bad trend of taking something to our north and south showing up. It's a mess overall and mean snow ticked down quite a bit. In the long range gefs still isn't awful but kinda meh. Ggem and eps are more optimistic about the long range. They imply several windows. The first day 6-9 is convoluted by several vorts in the trough. We don't really want one to get all the energy as that probably winds up too much and cuts but at the same time if the app split equally maybe nothing comes together. The EPS shows another 2 good looks around day 11-13 and again day 15. Mean snowfall in eps increased to 4" for Dca and was the best run so far but that is kinda spread out over the 3 windows. So not an awful run but didn't help provide more confidence in anything either.

Don't forget we cannot have the pv split or retrograde too far west either allowing warmth to flood in just something else that could go wrong

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I saw that, it's a good sign but that 4-5" eps has in our area is spread out across several threats so they aren't loving any one idea it indicate we have several shots.

 

Yup, great point and it's even more evident looking at the EPS Meteogram for DC.  The bar chart is steadily increasing at a constant clip with every 6-hr increment which tells me they're not keying in yet on a certain storm.  Lots of potential.  It's good to see that only 5 of 51 completely shut DC out of snow.  

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Best eps run by a good margin so far this year. Next weekend looks iffy but some support to not get blanked. Very good beyond that. At least 15 members show 5" or more for dca.

Dissecting op runs is still a futile exercise due to lead time. I like our chances quite a bit over the next couple weeks. Ens show no signs of the general pattern breaking down either.

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I don't have time to worry about every op run every 6 hours when a storm is in fantasy land but I look at the 3 main ensembles(gefs, ggem, eps) each cycle to get a general idea. Ggem given less weight of course but it can sometimes help split a tie between the gefs and eps.

 

I agree that the ensembles are the way to go in the long run.  Although the Canadian op run is a clear #4 among the global models, for some reason the Canadian ensemble seems to do relatively well at predicting H500 anomalies in the long run (around 10 days).  Below are the latest verification scores.

Uwkp6RY.png

 

I've only been paying attention to this since last winter, but more often than not I've seen the Canadian ensembles post higher H500 verification scores than the GEFS.  (They don't seem to do as well on other metrics, such as temperature.)  I'm not sure if there is some fundamental reason for this or if the Canadian ensembles have just had some good runs.

 

The NAEFS, which basically a combination of the GFS and Canadian ensembles, almost always does better than either of its components, and often by a significant margin.  This indicates that ensembles are currently limited by sample size.  Given that it's clearly better than the GEFS or GEPS, I'm surprised (and frustrated) that NAEFS averages aren't as widely reported.

 

For pay sites, I see no reason not to have some way to include all ensembles (including EPS) in the reported averages.  That would almost certainly be a far better long-range forecasting tool than any of the individual ensembles.  Does any site currently do this? 

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If you look at the latest ensemble runs there are other encouraging signs beyond blocking. The low height anomaly in the goa retros west far enough to pump up the epo and pna ridge with an amplified conus look and lowest heights in the SE.

One of the issues were seeing over the medium term is shortwaves not really digging deep and amplifying and airmasses run the risk of pac air moderation from energy running up and over the ridge in the west.

If the ensembles are right then that is going to be cut off. Northern stream vorts will be able to dig from way up north and a more classic split flow scenario where they can grab moisture from the southern stream and/or phase with the southern stream. The GOM will be open for biz as well for pure ns vorts.

The short story is temp issues are looking less likely attm after next weekend and it remains an active period. Folks in the SE should like what the latest ens runs are spitting out too.

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Don't forget we cannot have the pv split or retrograde too far west either allowing warmth to flood in just something else that could go wrong

That's the kind of detail that is pointless to worry about this far out. Things like that will change a lot over 6 days. It's why obsessing over every op run is pointless more then 100 hours away.

  

Best eps run by a good margin so far this year. Next weekend looks iffy but some support to not get blanked. Very good beyond that. At least 15 members show 5" or more for dca.

Dissecting op runs is still a futile exercise due to lead time. I like our chances quite a bit over the next couple weeks. Ens show no signs of the general pattern breaking down either.

Yea it's a good period of potential. I think because it's been so long waiting that some are rushing to judgement on each model run. We're not there yet. Still in general pattern diagnosis for another couple days probably. My take is we have an elevated chance at a decent snow the next 2 weeks. But elevated might just mean a 40% vs typical 5-10% during a normal winter period. It doesn't mean it's even likely just more possible. But I'm also fairly confident that we aren't done with chances if this window doesn't work. I expect more periods of blocking and threat windows into feb and maybe even March. It makes sense given past experiences when blocking like this shows up and howling they tend to last. I think we will have several chances and I expect us to cash in eventually but no one can tell yet of that will be jan 17, 20, 23, or sometime in feb. Luck probably will determine if we get one storm, several, or maybe none. I think luck plays way more of a role in snowfall then most admit. Yea the pattern stacks the deck but we still have to get lucky with so many things. Hopefully we draw some face cards soon!
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I agree that the ensembles are the way to go in the long run.  Although the Canadian op run is a clear #4 among the global models, for some reason the Canadian ensemble seems to do relatively well at predicting H500 anomalies in the long run (around 10 days).  Below are the latest verification scores.

Uwkp6RY.png

 

I've only been paying attention to this since last winter, but more often than not I've seen the Canadian ensembles post higher H500 verification scores than the GEFS.  (They don't seem to do as well on other metrics, such as temperature.)  I'm not sure if there is some fundamental reason for this or if the Canadian ensembles have just had some good runs.

 

The NAEFS, which basically a combination of the GFS and Canadian ensembles, almost always does better than either of its components, and often by a significant margin.  This indicates that ensembles are currently limited by sample size.  Given that it's clearly better than the GEFS or GEPS, I'm surprised (and frustrated) that NAEFS averages aren't as widely reported.

 

For pay sites, I see no reason not to have some way to include all ensembles (including EPS) in the reported averages.  That would almost certainly be a far better long-range forecasting tool than any of the individual ensembles.  Does any site currently do this? 

The plot you have posted is for 500 hPa temperature anomaly correlation.  Here is the figure for NH 500 Z AC:

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/ensm/allmodel/daily/dieoff/cordieoff_HGT_P500_G2NHX.png

 

This doesn't change your overall point, however...

 

The Canadian ensemble system is actually pretty well designed.  It is a full-fledged single core (unlike the SREF) multi-model/physics ensemble that uses and EnKF for initial uncertainty.  The NAEFS is a great tool and should be used much more than it currently is.

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If you look at the latest ensemble runs there are other encouraging signs beyond blocking. The low height anomaly in the goa retros west far enough to pump up the epo and pna ridge with an amplified conus look and lowest heights in the SE.

One of the issues were seeing over the medium term is shortwaves not really digging deep and amplifying and airmasses run the risk of pac air moderation from energy running up and over the ridge in the west.

If the ensembles are right then that is going to be cut off. Northern stream vorts will be able to dig from way up north and a more classic split flow scenario where they can grab moisture from the southern stream and/or phase with the southern stream. The GOM will be open for biz as well for pure ns vorts.

The short story is temp issues are looking less likely attm after next weekend and it remains an active period. Folks in the SE should like what the latest ens runs are spitting out too.

Great post. I was just looking at the EPS and I agree it looks really nice going forward. Looking @ h240 on the EPS, nice to see the GoA trough retro some. I had the same concerns about it inhibiting arctic air delivery. Western ridge axis in a good spot, low heights east of the maritimes under the block, and low heights in the gulf, and SE. That look should produce.

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If you look at the latest ensemble runs there are other encouraging signs beyond blocking. The low height anomaly in the goa retros west far enough to pump up the epo and pna ridge with an amplified conus look and lowest heights in the SE.

One of the issues were seeing over the medium term is shortwaves not really digging deep and amplifying and airmasses run the risk of pac air moderation from energy running up and over the ridge in the west.

If the ensembles are right then that is going to be cut off. Northern stream vorts will be able to dig from way up north and a more classic split flow scenario where they can grab moisture from the southern stream and/or phase with the southern stream. The GOM will be open for biz as well for pure ns vorts.

The short story is temp issues are looking less likely attm after next weekend and it remains an active period. Folks in the SE should like what the latest ens runs are spitting out too.

I wanted to mention that the day 10-15 period might be a better setup but worried it's NOT what people want to hear. Many are running out of patience but we're really just starting this pattern.
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I wanted to mention that the day 10-15 period might be a better setup but worried it's what people want to hear. Many are running out of patience but we're really just starting this pattern.

We are definitely still in the game Pre d10 at least. It may not be pretty or easy but something could easily come together. Even is its mixed or light I don't think a single person would get mad at a couple inches. The good thing is it seems that we are just at the beginning of a period that can work for us and it might have legs.

We need long windows in the MA. No doubt about that.

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The plot you have posted is for 500 hPa temperature anomaly correlation. Here is the figure for NH 500 Z AC:

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/ensm/allmodel/daily/dieoff/cordieoff_HGT_P500_G2NHX.png

This doesn't change your overall point, however...

The Canadian ensemble system is actually pretty well designed. It is a full-fledged single core (unlike the SREF) multi-model/physics ensemble that uses and EnKF for initial uncertainty. The NAEFS is a great tool and should be used much more than it currently is.

Why do you think it isn't more widely available?
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