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January Medium/Long Range Discussion Part 2

WinterWxLuvr

By WinterWxLuvr,
in Mid Atlantic

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eurojosh

eurojosh

Posted
Posted
1 minute ago, Windman18 said:

gem_mslp_pcpn_frzn_us_30.png

CMC much improved over last run. Has the low and the high in pretty good spots. Looks like this could be a time period to keep an eye on.

Then a mess behind it coming up from the gulf. What a cluster the whole week is. Very complicated.

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psuhoffman

psuhoffman

Posted
Posted
33 minutes ago, Ender said:

Looks like the 0Z GFS might have caught on to the EC's thinking?

Maybe...? 

Maybe, snow from this setup has always been unlikely. But both the euro and gfs have been flipping around between a wet or white solution for several days now. If the gfs holds that look and so does the euro for a couple runs, plus we see the ensembles which are probably more important at this range drop the signal, then yea it's time to punt. But while I agree this is likely a wet not white end result one day 8 run of the gfs is not going to be the end all I base much on. I've over reacted to one run way too often only to see a solution flip back the next day to make that mistake again. 

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Ender

Ender

Posted
Posted

One thing that's impressed me this winter...as much as we like to criticize is the GFS a damn good model. No, It's not the Euro's equal, it tends to lag the euro by 12 - 18 hours on the "ah ha" moments that lead to a significant synoptic shift (ie up the OV as opposed to a costal) but it doesn't waiver much after it comes to that ah-ha moment. The euro, however, does a bit. It did a few times with this last system during its last seven days. Just a few cycles where it varied the track off the SE coast from Deep South to MA, while the GFS basically kept nearly the same track (though varying intensifies). Now admittedly those few times that the Euro-OP went a little wayward it had practically zero support among its ECE members. Still an impressive improvement over the bipolar GFS of just two winters ago.

Then we have the GFSX. When there's an "ah ha" moment coming, one tbat the Euro picks up on at 12Z as the GFS-OP fails to see, the GFSX will often have jumped on that idea at 6Z. It would seem that the GFSX might be with 6 to 12 hours, sometimes same cycle, on those epiphanies. I'm sure the euro is still kicking everyone else's ass on anomaly correlation, and that's obviously important, but, personally I care a hell of a lot more about practical WX IMBY as I'm rarely close enough to one of the handful of global anomaly centers to truly appreciate the full benefits of the euro's statistical edge.

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psuhoffman

psuhoffman

Posted
Posted
19 minutes ago, Ender said:

But it can't. Heights are rising, being forced to by upstream events...the column is expanding and warming....the arctic high is getting devoured (the little of it that's not getting shoved ENE). 

The high can't hold in that setup. We would need the boundary to push further south after the day 6 wave then have a weaker system come across and slide under. If either the boundary sets up that far northwest or the system cuts off in the miss valley then yea it's game over.   

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Amped

Amped

Posted
Posted
3 hours ago, Windman18 said:

gem_mslp_pcpn_frzn_us_30.png

CMC much improved over last run. Has the low and the high in pretty good spots. Looks like this could be a time period to keep an eye on.

The only model showing some ZR. This is a classic ice storm setup on all models, very similar to January 13-15 1999.  GFS definitely underdoing surface cold would be a lot more ZR than shown. And of course, I'm not buying the ensemble members that show snow.

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mitchnick

mitchnick

Posted
Posted
10 hours ago, psuhoffman said:

Mean temps are misleading at that range. Several euro members disagree on timing and or have a cutter pumping warmth up ahead. Of course if those solutions are right none of this matters. But the roughly 40% of the EPS that had a more southern solution we see at least some snow. The mean is washing the two camps out to a half way in between look. I agree it's a greatly flawed setup but not as dire as that temp profile makes it seem. 

It might be 3rd and 15 after a sack but as flawed as this setup may be I'm not punting threats until it's 4th down.

This is where I disagree with respect to the use of ensembles.  If we are going to accept that the ensemble mean is showing strong High Pressure to our north,  then we should accept the mean 850 temps. I don't think we can look at individual members to support a position since they just make up the mean. In any event,  we don't have a shot at anything/snow, imho, as long as we have elevated heights over us. I hope ma nature proves me wrong, but I seriously doubt it. 

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psuhoffman

psuhoffman

Posted
Posted

Overnight runs took a step away from the day 7 threat. All guidance moved towards a stronger deeper trough coming across. That's not good because 1050 high or not there is ridging building over us and any strong cut off or deep system in the central us will only pump the ridging ahead and push the high out of the way. It will slow and cut vs slide under. 

Both gefs/EPS do still have some members with snow. They get there by ejecting a wave ahead of the main system. Gefs is more bullish on this with about half the members having a modest snowfall with that feature. EPS has way less members showing such a solution but oddly enough the ones that do are big hits. 

Looking at specifics the timing is off between the gefs and EPS on both the high and energy coming across. The gfs has almost no seperation between waves which would be preferable but it's also slower with the high and brings it across further north. So quite a few manage to get the boundary south enough for a part of one of the waves to get some snow into the area. Either the end of wave 1 or the start of wave 2. 

The EPS brings a 1050 high across the southern lakes but almost a day ahead of the gefs. It also has more seperation between waves. Wave one is long gone before the cold arrives. Wave two is still sitting way out west. The timing is off for our needs. Timing is everything because there is nothing to lock the high in. It will just move across so our windows of opportunity is only 24-36 hours. The better location of the high on the euro leads to an all or nothing with the front runner ejecting day 6/7. It doesn't go to our north. The snow on the EPS north of us is from the storms day 3-5 and a cutter day 9. Our system day 6/7 gets squashed by most of the runs. Some show some light snow or ice south of us but mostly they just suppress the system to some light rain or nothing to our south. The few members that eject enough energy with the front runner though are big hits 6"+. 

What we want would be the euro timing and location of the high and the gfs idea on the timing of the waves. 

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Scarlet Pimpernel

Scarlet Pimpernel

Posted
Posted

PSU and others...thanks for some great analysis and commentary!  Obviously most of us (myself included) have been more focused lately on the event yesterday, but now that it's done I've started to wander more into the more general medium range discussion.

I have looked some at the system you're talking about next weekend-ish, and yeah, it's not the greatest setup.  I know there were some model and even ensemble runs that looked pretty good, but for the reasons that have been stated, it seems kind of dubious.  Not punting or anything like that, but not getting overly excited (yet, at least!).  That said, it could be very interesting at least perhaps at the beginning, even if it's a stronger system that cuts and we get mostly rain anyhow.  Just too bad we cannot get that 1050 high at a time when there's a decent block in place, eh? ;) But as has been said, nothing really to make it stay put with that flow.

Beyond that, yeah, a period of relative hibernation if you're looking for any snow!  Hopefully the warmup and hostile pattern last only a week or so, and hopefully the indications after it (mentioned in the talk about the Euro weeklies) are for better times as we close January and go into February.  We'll see.  It would be kind of cool to manage to score something decent before the pattern goes to hell, rest for a bit, and then come back again for the 2nd part of winter!

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psuhoffman

psuhoffman

Posted
Posted
39 minutes ago, mitchnick said:

This is where I disagree with respect to the use of ensembles.  If we are going to accept that the ensemble mean is showing strong High Pressure to our north,  then we should accept the mean 850 temps. I don't think we can look at individual members to support a position since they just make up the mean. In any event,  we don't have a shot at anything/snow, imho, as long as we have elevated heights over us. I hope ma nature proves me wrong, but I seriously doubt it. 

Your right on both counts in a general sense. Getting snow with higher heights at h5 is difficult. But we have had snow before during patterns that just looking at h5 you would think how did that happen. It's rare so it's good to be skeptical and I've said I doubt this works out but I'm not dismisding it totally out of hand either. It's not impossible. 

As for the ensembles the details do matter. If there is consensus then the means matter more. But once you get past day 5 details start to get washed out some by means. Sometimes it can be timing differences. Sometimes divergent camps.

 It changed last night so this is moot but the run we were discussing if you looked within the members there were about 20 that ejected a weaker wave under the high. The other 22 has a consolidated cutter.  The cutter camp had the 850s way north. But 18/20 of the southern track camp had snow in our area and 850 south of us. The average of the two camps put the boundary half way in between the two ideas. That's not a good idea of where it's going to be. If you buy the cutter it's likely north of that. If you bought the weaker south idea it would be south. 

Better example might be last years blizzard from about 9-10 days out. After the threat first showed itself I remember someone in another forum, I think NYC, posting the day 10 EPS temps to say it was going to be too warm. But if you looked at the individual members the 40% or so that had the storm were cold. The 60% that had no storm were warm. So the details showed temps weren't as much of a problem as the means would look. 

All that said the means give a general idea. And I'd rather see it south then north. But the means don't always tell the whole story or show the details well. 

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psuhoffman

psuhoffman

Posted
Posted
7 hours ago, Amped said:

The only model showing some ZR. This is a classic ice storm setup on all models, very similar to January 13-15 1999.  GFS definitely underdoing surface cold would be a lot more ZR than shown. And of course, I'm not buying the ensemble members that show snow.

That period in 1999 actually shows up in the analogs. 

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mitchnick

mitchnick

Posted
Posted

In keeping with Ender's post that analogs show a decent February (at least increased odds), super ensemble years showing up from last night's run all had decent Febs (AN snows at BWI) or  decent snow storm(s) in late Jan or Feb, save 1.

http://www.cpc.ncep.noaa.gov/products/predictions/short_range/tools/gifs/500hgt_comp_sup814.gif

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cae

cae

Posted
Posted
8 hours ago, Amped said:

The only model showing some ZR. This is a classic ice storm setup on all models, very similar to January 13-15 1999.  GFS definitely underdoing surface cold would be a lot more ZR than shown. And of course, I'm not buying the ensemble members that show snow.

I think the GGEM had the best handle on surface temps (of the globals) during the December ice storm, and it has doing well on surface temps in general.  The below charts are the the root mean squared error (top) and bias (bottom) for North American temps at 1000 hPa over the last month. 

fXTrdZ5.png

y8fmNf3.png

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showmethesnow

showmethesnow

Posted
Posted
1 hour ago, psuhoffman said:

Gfs back to a southern wave but the timing with the high isn't going to work. High is sliding out ahead of the system. Threat for some ice is there though. 

12Z CMC has a similar evolution as the 06Z GFS with ejecting a piece of energy ahead of the main low. Provides a Southcentral PA and MD jackpot of 3-6 in.

Think our chances would be better with this evolution, boundary sinking south through our region with a piece of energy running into CAD from the departing High, then depend on a well placed strong low in lock step with a northern high in conjunction with a southeast ridge. Think there is too high a probability of fail with that second scenario.

At least this will provide something to watch before we take a hiatus from serious tracking for a week or two.

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