December 2019 Med/Long Range Disco

[Scarlet Pimpernel]

36 minutes ago, psuhoffman said:

Gfs shows the path to a white Xmas miracle. 

Miracle on K Street!!

[Bob Chill]

For 10-12 days out, this is a pretty good storm signal. Some legit coastal nukes mixed in with the rainers. 

[JakkelWx]

4 minutes ago, losetoa6 said:

Anybody guess this  500mb composite 

 

Hint?

[JVscotch]

5 minutes ago, losetoa6 said:

Anybody guess this  500mb composite 

 

December 2009?

[frd]

 

Never really thought about the role of cyclonic wave breaking and the location of the TPV.  

 

 

 

 

[frd]

1 minute ago, losetoa6 said:

Winner winner chicken dinner...^

Gift card would be cool .... I love coffee :-) 

 

[frd]

 

Can anyone confirm the HH GFS has a massive Scandinavian ridge modeled out in fantasy land. 

 

[Bob Chill]

4 minutes ago, frd said:

 

Can anyone confirm the HH GFS has a massive Scandinavian ridge modeled out in fantasy land. 

 

Yea, it's pretty massive but it also doesn't start forming until d8+. GEFS has some support for the idea but not enough to favor the idea.

[JakkelWx]

5 minutes ago, frd said:

 

Can anyone confirm the HH GFS has a massive Scandinavian ridge modeled out in fantasy land. 

 

Has a strong scand ridge forming around D9 and remains in place to the end of the run. Can see it feeding the -NAO in the NAO region. GEFS also supports the OP with a scand ridge forming around the same timeframe as the HH GFS.

Edit: Ninja'd by Bob

[frd]

A follow-up on this, as HM spoke about this about a week ago.  The interesting thing is, as Hugo mentions, since it is from the Euro it raises the eye brow a little more. If anything, displacements and elongations can benefit us.  No worries about a SSWE, but these little things do matter. 

 

 

[Bob Chill]

ICON looks like the eps members that hit us with the waa piece on the next one. It's a decent setup if things are spaced out right. A little more push from the 50/50 and this could be a big hit

[Ji]

Icon with a thump to rain

[Bob Chill]

1 minute ago, Ji said:

Icon with a thump to rain

A number of 3-6" events have happened over the years like the icon is showing. Euro control was similar

[yoda]

00z GFS wants no part of what the ICON shows and blows up a huge cutter for middle of next week - but it does bring in some nice arctic air in the process as it moves into Canada

[nw baltimore wx]

13 minutes ago, Bob Chill said:

A number of 3-6" events have happened over the years like the icon is showing. Euro control was similar

Yep. And then dry-slotted with foggy drizzle. We had a lot of front end storms like that where I came home soaked to the bone from sledding, carrying my dead right arm in my left hand because I heaved too many snow balls.

[yoda]

If that HP in the Northern Plains can move in tandem with the SLP in LA at 240 on the 00z GFS...

And a southern slider... with rain.  Interesting...

[Ji]

If that HP in the Northern Plains can move in tandem with the SLP in LA at 240 on the 00z GFS...
And a southern slider... with rain.  Interesting...

Were going to have 15 near misses this year like 2000-2001

[yoda]

00z Euro has a quick thump late Monday before changing to rain on Tuesday morning

[yoda]

Before the Monday system... total snowfall for the area predicted by 00z Euro by 12z Monday

 

Total snowfall by 06z TUES... by this time most everyone has changed to rain or is in the process of N and W of the metros... no real additional accumulations are shown after this image for the LWX CWA 

[CAPE]

Looking out into LR fantasy-land, where we don't fuss over the details, I like where the pattern appears to be going here. Great HL look and the deep trough off the west coast evolves into a broad trough with ridging over the top.

[Chris78]

4 hours ago, yoda said:

Before the Monday system... total snowfall for the area predicted by 00z Euro by 12z Monday

 

Total snowfall by 06z TUES... by this time most everyone has changed to rain or is in the process of N and W of the metros... no real additional accumulations are shown after this image for the LWX CWA 

Id sign on the dotted line for that. Need to stop the bleeding. Trending towards the gfs.

[LP08]

1 hour ago, losetoa6 said:

I'll take the Ukmet look for now for the early week storm ....if anything this is probably a se slider verbatim.  A bump nw at game time and we r on.

Precip and temps at that time.  Looks like the best of the bunch so far.

 

[psuhoffman]

1 hour ago, C.A.P.E. said:

Looking out into LR fantasy-land, where we don't fuss over the details, I like where the pattern appears to be going here. Great HL look and the deep trough off the west coast evolves into a broad trough with ridging over the top.

When the western trough first showed up there was fear of permanence because we couldn’t see beyond.  The reason I’ve suspected it’s not was how it coincides with the rising heights in the AO and NAO domain. Often that creates a shake up because the TPV weakens and gets displaced. If it gets forced west that often causes a temporary trough west ridge east look until the blocking establishes and usually the jet then splits and cuts underneath and then it’s go time. And frankly given the blocking and the propensity for 50/50 lows this year I’m not sure we ever suffer a prolonged torch. Might just continue this seasonal variance with storm chances if we get lucky with timing then roll right into a blocking regime (if the blocking is real). That is a huge if though but there are reasons to be optimistic. 

[CAPE]

7 minutes ago, psuhoffman said:

When the western trough first showed up there was fear of a permanence because we couldn’t see beyond.  The reason I’ve suspected it’s not was how it coincides with the rising heights in the AO and NAO domain. Often that creates a shake up because the TPV weakens and gets displaced. If it gets forced west that often causes a temporary trough west ridge east look until the blocking establishes and usually the jet then splits and cuts underneath and then it’s go time. And frankly given the blocking and the propensity for 50/50 lows this year I’m not sure we ever suffer a prolonged torch. Might just continue this seasonal variance with storm chances if we get lucky with timing then roll right into a blocking regime (if the blocking is real). That is a huge if though but there are reasons to be optimistic. 

Yeah we discussed this a few days ago. I never felt like we were heading towards a prolonged PAC flood. Been seeing indications of rising heights up top for a while now on the means. There has been some persistence now going well back into November with some of the key features(e.g. Aleutian low), and an overall propensity to keep things on the cold side. Looks generally cold and active going forward. If next week's event doesn't pan out, it may help to set things up for the period before Xmas.

[frd]

6 minutes ago, psuhoffman said:

And frankly given the blocking and the propensity for 50/50 lows this year I’m not sure we ever suffer a prolonged torch. Might just continue this seasonal variance with storm chances if we get lucky with timing then roll right into a blocking regime (if the blocking is real). That is a huge if though but there are reasons to be optimistic. 

I hope Webb is correct about the weakening + IOD releases its hold on the tropics and enables better forcing and a more conducive NAO domain. 

Will be of interest to track the Scand ridge event on the modeling.   

[frd]

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

If next week's event doesn't pan out, it may help to set things up for the period before Xmas.

There were a few weather pros / weather event historians , etc. who mentioned several 1960s type analogs for later this month a while back.

Of course, one is  Uncle who liked 1966, I think the Christmas eve snowstorm.   

What seems to be working, but maybe not as cold, ( at least so far ) , is the PMM .  Back ion September severeweatherblog brought it up, and stated the correlation in December would be for a cold East and very active in terms of precip.  Seems to be working so far.  The correlation also calls for increased phasing of storms.   

[psuhoffman]

6 minutes ago, frd said:

I hope Webb is correct about the weakening + IOD releases its hold on the tropics and enables better forcing and a more conducive NAO domain. 

Will be of interest to track the Scand ridge event on the modeling.   

I must have missed that call while I was enjoying this December torch. 

Sorry it’s too easy after he was a jerk to everyone. But he knows his stuff and he very well may be right and perhaps the IOD was a hindrance but instead of causing a torch it simply muted what would have been a better pattern in December. His mistake was focusing on just one factor and then making such a concrete declaration based on that...then carrying on like a pompous arse when there was dissent. 

[frd]

 

I like the mention here of 60 West .  This is a cool animation. 

 

 

[psuhoffman]

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

Yeah we discussed this a few days ago. I never felt like we were heading towards a prolonged PAC flood. Been seeing indications of rising heights up top for a while now on the means. There has been some persistence now going well back into November with some of the key features(e.g. Aleutian low), and an overall propensity to keep things on the cold side. Looks generally cold and active going forward. If next week's event doesn't pan out, it may help to set things up for the period before Xmas.

Concur with all this. If we can get some snow around Xmas it bumps the winter grade up a notch imo. 

[showmethesnow]

May not seem like it, especially if you look at the surface and snowfall maps, but the Euro made a positive move at 500s on what I believe is key on next Mon/Tues possible storm. What we saw on the EPS could be nothing more then noise, but at least that noise is in a positive direction as well.

Below we have the lead up to our storm when it is just to our southwest. Now assuming that the Euro is somewhat accurate with the pseudo 50/50 at this time (has been steady for the last day of runs at least) then the question is, 'what do we need to see?'. I think it all boils down to with how much, if any, interaction we see between the Mid-Latitude trough and the PV. Currently as depicted the more interaction between these features the sharper and farther west we will see our storm cut.  And short of seeing the models shift those two features eastward several hundred miles the current projected farther westward placement (far from ideal for our current needs) argues for a cutter. 

That brings us to what we saw as far as run over run changes from yesterdays 12Z run and the overnight run. This all pretty much ties in with my comment of why yesterdays 00Z run had such a good solution. And that has to deal with needing to see higher heights then currently projected separating the PV and the mid-latitude trough. In simple terms the higher the heights between these two features the less interaction we will see between the two. Now you can get the feel for this by comparing below to what we saw from yesterdays 12z (2 maps below). If you note we were seeing the stronger height anomalies joining the PV to the trough on the 12z. And yet when we look at the latest run we are seeing a disconnect between these greater neg anomalies (red circle) this is telling us there is less interaction going on. To give you a clearer idea of the heights changes we are seeing look 3 maps below where we have the run over run changes. As can be seen we are seeing higher heights showing up between these two features.

Current run 500s

 

Now some may ask, 'If we are seeing the changes we need then why did we see a degradation with the surface with the low cutting further west?'. That has to deal with energy we are seeing rotating through just underneath the higher height builds we have seen (circled shortwave above). It is timing well to drop into the backside of the trough deepening the upper latitude portions of the trough. The response is to see a goosing of the ridging in the east in the upper latitude portion of it as well(can be seen on the run over run changes map below). These two in combination are creating a steeper N/S axis on the front side of the trough. This does two things. It pulls the boundary quicker to our north as well as gives more room for the southern low to intensify quicker with a sharper northward movement. Now to worry about this energy at this time is pointless (almost 6 days out). Models don't handle these packets of energy well at leads and it is just as likely we see this feature running ahead of the trough knocking down the ridging/heights in the east helping to keep the southern low from cutting. That is if this energy even exists.

One final comment about the top map. Notice where we see the 50/50 located and how it gets there (black arrow). Not the greatest path, timing and location for what is considered a transient low. It helps the cause upstream through our region somewhat but it could do more. We see that swing farther to the south and east (red arrow) it improves the placement as well as the timing between it and the incoming central US trough.

 

Yesterday's 12 z run

 

 

Run over run changes

 

One final comment. For those that have already given up on Mon/Tues, I probably wouldn't. That time period is still very much in play. Barring a major reshuffle on the setup the look being presented is a very winnable one with just some minor changes.