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January Medium/Long Range Discussion Part 2


WinterWxLuvr

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17 minutes ago, PaEasternWX said:

If we can score Feb 6-10 it will not matter. Lol just want 1 good storm.

That is the the period I am referring to. Right now the GEFS looks solid, and not so good on the EPS.

The solid -AO/NAO look the EPS had on previous runs during that window has now disappeared. Without the higher heights up top, it is going to be difficult to bring significant cold into the east outside of a glancing blow.

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13 minutes ago, C.A.P.E. said:

That is the the period I am referring to. Right now the GEFS looks solid, and not so good on the EPS.

The solid -AO/NAO look the EPS had during that window has now disappeared. Without the higher heights up top, it is going to be difficult to bring significant cold into the east outside of a glancing blow.

Yea the Euro does build a positive AO from about day 6-11 but then breaks it down quickly.  The 6-10 day period is ruined by a strong trough crashing into the west.  Its transient and does slide east but the timing sucks as it pumps ridging out in front just in time to flood warm air under the period of better heights up top.  By the time we recover and cold is pushing into the CONUS again we lose the ridging over the top.  It never reverts to a positive AO looks more neutral in the long range.  That could be indicative of a war going on within the ensemble members about where to go, or they simply think the new base state might be more neutral.  But after several days of very good trends last night was a step in the wrong direction wrt the AO flip.  The GEFS reverts back towards neutral late in the period also but holds on long enough to open a really nice window in the day 10-15 period.  

After that its not hopeless.  That block up near Alaska could give us another opportunity if it cycles east again pressing down on the cold that seems to build in western Canada again. That or it wouldn't take much to see the heights build again on the atlantic side, none of the guidance reverts to the strong PV over the pole look we have been stuck in for a while now.  My overall take is we are heading into a "workable" pattern.  Nothing looks amazing.  Nothing I can post with the "its happening" gif, but nothing that looks like we would be without any chance.  Just variable biased towards average.  Get some luck with timing during periods when the boundary is pressing south and we could easily score something in the look were seeing in general.  

The long range is also shifting around way more then usual right now.  I know its in vogue to blast the long range guidance right now because we are frustrated with our lack of snow, but honestly in were just trying to identify general patterns the guidance has been pretty good this year.  We saw all of the colder and torch periods from range.  Yes they were all biased too low on the AO in the long range, but the overall pattern was identified each time.  Right now they are shifting around pretty big from run to run on how much blocking, where the blocking sets up, moving that uber block up near AK around and that shifts all the other features since it seems to be the most dominant driver up there.  Right now the guidance is of lesser value then normal in the long range.  

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digging into the individual members of the EPS there is divergence around day 10.  There is about 2" on the snow mean almost all of it coming in the day 11-14 day period.  2" spread out evenly over 15 days would be a really weak signal but when its concentrated almost totally within a 3-4 day window its actually not a horrible signal for something right there.  The mean wouldn't indicate this but when I look at the individual members its obvious that a decent cluster agrees with the GEFS evolution.  Its a see saw idea up top, more ridging near Greenland forces more troughing under it in the east.  Less there and more near AK and you dump more into the west and ridging builds in the east.  Just looking at day 10 you can tell which members on in each camp by where they have the boundary.  The surface plots only go to day 10 for euro members, but snowfall goes to 15, and you can see the members that have the baroclinic zone down to our south day 10 have a high percentage of snowfall a couple days later.  The members that are already pushing the boundary north and are near our latitude or north of us at day 10 have nothing.  So the EPS doesn't necessarily have no support for the GEFS's strong signal for a storm threat in the day 10-15 period they simply are more split on how much ridging there is on the atlantic side and therefor where the cold boundary will be in the east.  

Before we get a dozen "seasonal trend" posts I would concede the way to err right now would be on the side of less ridging in the NAO domain and therefor a worse outcome, or err on the side of no snow given the trends this year, but if we are simply analyzing the pattern shown on the guidance its not that bad.  And if we simply take seasons where we had very little snow region wide at this point, odds still favored about 65-35 that we get at least one decent snowfall event in Feb or March.  I am NOT at all feeling like some kind of magical flip like 1914/1958/1960 is coming where we pull out a second half miracle save but if were simply trying to avoid the total shutout and score one decent snowfall the odds still favor that happening at some point.  We still have roughly half of our snow climo period left to go. 

ETA: more specific numbers for the EPS

Almost all of this snowfall comes from a system in the day 11-14 period.

16 members have over 2" for DC, 24 members for the NW part of the region

11 members have over 4" for DC, 15 members NW

There are a couple misses to the south and a handful just to the north, but the majority either have snow in the area, or are not even close showing the divergence in the pattern during that period.  

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16 minutes ago, mitchnick said:

It says the "Target Month" is February. Maybe it's just that the target is moving?

yea the CFS is a pretty awful tool.  However, others have pointed it that once within a week of the target month it does have "SOME" accuracy.  It has been locking in on the general idea of a -AO/NAO and trough in the east for the last several days.  I suppose it will be interesting to see if this holds the next few days and then perhaps we can say that combined with a similar look from the euro weeklies the odds of a better February as a whole are slightly increased.  

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5 minutes ago, PaEasternWX said:

Compare 6z to 12z. Major changes, implications anyone?

 

USA_VRTHGTGRD_500mb_096.gifUSA_VRTHGTGRD_500mb_102-2.gif

It definitely trended sharper and more amplified. It's not where we need it but if that trend were to continue it still has time to become something. I'm not betting on it though.  It's fighting a pretty suppressive trough axis in general. 

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9 minutes ago, PaEasternWX said:

Opps I got that backwards didn't I

What I notice so far is the block over AK is quite a bit further NW this run so far at 180 hours, and that combined with timing differences creating more separation between the system exiting the east and the one crashing into the west is allowing more ridging in the middle of the CONUS.  This could allow the system to cut down the line but it depends how it evolves. Overall I am not a fan of the look but predicting things a few days downstream is difficult.

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What is becoming really clear on all the guidance is that our fate will be tied to the ability of that block near AK and or any higher heights near Greenland to press down and suppress things. All the guidance indicates were looking at fairly progressive flat flow underneath whatever goes on up there.  Broad wavelengths and generally not a lot of amplification.  Even the runs that show a lot of snow do it with pretty pathetic surface systems.  Mostly overrunning driven.  Were not likely getting some coastal bomb in the next couple weeks so we need things to be pressed south as much as possible.  Either get the PV suppressed by the ridging to its north or the block near AK, or good timing where a lobe presses down just as something is coming across.  But it looks like a gradient type pattern and we have to end up on the right side.  

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1 minute ago, psuhoffman said:

What is becoming really clear on all the guidance is that our fate will be tied to the ability of that block near AK and or any higher heights near Greenland to press down and suppress things. All the guidance indicates were looking at fairly progressive flat flow underneath whatever goes on up there.  Broad wavelengths and generally not a lot of amplification.  Even the runs that show a lot of snow do it with pretty pathetic surface systems.  Mostly overrunning driven.  Were not likely getting some coastal bomb in the next couple weeks so we need things to be pressed south as much as possible.  Either get the PV suppressed by the ridging to its north or the block near AK, or good timing where a lobe presses down just as something is coming across.  But it looks like a gradient type pattern and we have to end up on the right side.  

Yeah. The southern stream is nearly dead so far on the latest GFS run. Definitely showing a progressive pattern. Not that we cant score some nice little events like that.

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3 minutes ago, clskinsfan said:

Yeah. The southern stream is nearly dead so far on the latest GFS run. Definitely showing a progressive pattern. Not that we cant score some nice little events like that.

Huge differences in terms of timing of systems coming in.  There is a system around the 4th that didnt even exist last run, and the system that was our snowstorm 6z is a day faster and right on the new systems heels.  The first system comes in during the relax between troughs and so it cuts up to our north and then the second being a day faster allows it to ride the boundary before it has any chance to sink south.  End result rain then more rain.  The major players are mostly the same at H5 except the AK block is noticably further northwest and that is not all that good.

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2 minutes ago, PaEasternWX said:

So it did end up cutting a little bit as I speculated but it was close to being decent. 

 

Also a GL low before the system f** up temps. Was non existent last run 

Its way too far out to be worried about details.  The timing of the vorts screwed everything up this run.  System comes across ahead of the cold shot and delays it then the one we were watching comes right on its heels and rides up the stalled boundary to the west.  That exact evolution is likely to adjust and change several more times.  Way more interested in what the ensembles say from that range.  

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148 high coming into the midwest as a system organizes in the gulf day 14.  Maybe the convoluted mess earlier sets up another threat behind it.  None of this is likely to look anything like this but I enjoy the entertainment of the run none the less.  

ETA:  suppressed, big ice storm for Carolinas 

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1 minute ago, Bob Chill said:

The shortest version of what I see:

- Anything inside of 10 days would be moisture starved and light

- Beyond 10 days is a continuation of timing and luck with no chance at clarity for 5-7 days or so

Back to sleep now. 

yea good summary.  Some of us are bored... a week of mid term testing and now babysitting students while they work on their semester thesis projects in the computer lab, with nothing to grade because its the start of the grading period.  This job shifts between days where I have no time to even sit down, and days where I am bored out of my mind.  The last couple weeks are more of the bored out of my mind variety.  

FWIW the GGEM is a much better look day 10 and seems to be setting up the threat for day 12ish.  Doesn't have that day 9-10 wave that messes everything up on the GFS.  

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15 minutes ago, Bob Chill said:

The shortest version of what I see:

- Anything inside of 10 days would be moisture starved and light

- Beyond 10 days is a continuation of timing and luck with no chance at clarity for 5-7 days or so

Back to sleep now. 

Bob - just curious, you guys ever been held below 5" for a winter?  What are you at 2-3"?

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2 minutes ago, packbacker said:

Bob - just curious, you guys ever been held below 5" for a winter?  What are you at 2-3"?

Heh, I wish I was at 2-3". My yard has just over 1" and it took 2 events to get there. lol

We've had some real stinkers. 2011-12 was below 5" pretty much region wide. 2012-13 was probably over 5" in my yard but the way I got there sucked so bad it doesn't even count. The winter was a abomination. 2001-02 was horrid and below 5" in the cities. 97-98 got the northern and western areas ok. But sucked near the cities. I was living in CO during that one though so I don't have any bad feelings towards it. 

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