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December 2019 Med/Long Range Disco


Bob Chill
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Just now, Bob Chill said:

That's actually showing on the ensembles as well. There's a camp that pushes a back door front through our area right around Christmas. Certainly possible but would be nothing more than an intermission between some pretty mild Dec wx. 

I would take it considering the date and maybe it will have some clouds with it.  less days with above normal temps are checks in the win column.  I mean the CMC is real chilly Xmas Eve.  10 days, lots can happen. 

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Several of the euro members from last night showed scenarios like this one.

Yesterday none of the euro members were showing snowfall for the mid Atlantic region this weekend ! 
So to have a few members that now show the possibility of Significant snowfall this weekend is a huge step in right direction for us all! :thumbsup:

65A63600-4B3B-4947-9BDF-2B57AEC2B8E8.jpeg

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14 minutes ago, Bob Chill said:

It's a process. Looks like at least 2 large scale intrusions of maritime air between now and the end of the month. GFS shows how fast things can turn around. D10 looks awful with temps but by d16 there's expansive cold in our source region. I'm not hunting a big dog or even a small dog... I'm hunting the way out of the "snow? hell no!" pattern. 

I am not really concerned with "recovery time".  It's December not February.  And if we get cross polar flow from an EPO ridge we can get cold again right quick.  It takes longer if we get NAO and PNA but no EPO help, but even then enough cold to snow at least mid winter can build domestically within a week or so.  Either way time is on our side.  The reason these seem to "linger" forever is often when a really awful pattern locks in it can take a while to break down.  If the pattern breaks we will be ok by prime climo and that is all that matters.  Most of our "good" and even a decent percentage of our epic winters the snow comes in chunks with long periods of meh that we just don't remember after the fact.  What those good winter's usually avoid though are month long total crap shutout patterns.  So far we have avoided that.  As long as we bounce out of this Pac Puke pattern within a week or so I am ok with this.  I still think the propensity for blocking up top on either the EPO or NAO side will pay off eventually.  So far we have not timed either up with enough cold.  I still think if we simply get a recycle of the pattern from the last 8 weeks in mid Winter we will do just fine.  Take what we have seen and add more cold to the equation and we probably had 2-3 good snow events.  

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Just now, Waiting on snow said:

Looks good up top sure. But how the hell do we get rid of that awful -PNA? I mean with that look how is the cold air dumping into the west?

Getting the ridge above the san diego trough is step #1. IMO- step 2 is rolling the trough in the west forward while the TPV presses down from above and we're right back into some semblance of a pattern that can produce. We can work with a trough in the west as long as it's not dropping down from the GoA hosing the continent in the process. D10 GEFS implies the end of the pac hosing and the beginning of the cold factory getting back to work. Getting out of what we're seeing over the next 10 days is a multi step process. It won't go from epic disaster to ripe in a blink. 

 

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@psuhoffman @C.A.P.E.

CFS weeklies have consistently improved for Jan. It's an interesting pattern and it fits what we're seeing on the ens late in their runs. The EPO ridge axis isn't optimal as it's a bit too far west but the Atl looks to offset some of that. Very gradient like pattern showing up and not that far away. Precip anomaly plots imply normal to above normal QPF from weeks 3-6

Weeks 3-4 look workable and the weekly trend is colder as you go out in time so weeks 5-6 are better than these:

cfs-avg_z500aMean_nhem_3.png

cfs-avg_z500aMean_nhem_4.png

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2 minutes ago, DCTeacherman said:

Really a shame that low just sits and rots in the GOM on the 12z Euro....would've been nice if there was something to bring it up the coast. 

I'm not sure there's a path to frozen even if it does climb the coast. Without some sort of northern stream interaction the mid levels are scorching all the way to Canada. 

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1 hour ago, BristowWx said:

Yeah but so wildly different than just hours ago in the last run.  something to keep an eye on I suppose.  still far enough out that changes could be interesting. 

FWIW Gfs was seeming to “Bring it back” early on as well. More ridging out ahead of it. Not sure it ends up being anything but it came across my mind when seeing it. 
 

edit-and just seeing what Bob posted about it being frozen is also a worry as ridging is the likely reason for seeing it pop but the byproduct is scouring our precious cold in advance. Just not a winning setup verbatim

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1 hour ago, Bob Chill said:

@psuhoffman @C.A.P.E.

CFS weeklies have consistently improved for Jan. It's an interesting pattern and it fits what we're seeing on the ens late in their runs. The EPO ridge axis isn't optimal as it's a bit too far west but the Atl looks to offset some of that. Very gradient like pattern showing up and not that far away. Precip anomaly plots imply normal to above normal QPF from weeks 3-6

Weeks 3-4 look workable and the weekly trend is colder as you go out in time so weeks 5-6 are better than these:

 

 

Yeah I mentioned the weeklies the other day when they had a generally cold look but it was completely EPO driven, with more of a a +AO/NAO look. Latest runs are better up top for weeks 3-4. I never pay too much attention past that as it's very likely to change, but that is a cold and active look.

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46 minutes ago, Bob Chill said:

@psuhoffman @C.A.P.E.

CFS weeklies have consistently improved for Jan. It's an interesting pattern and it fits what we're seeing on the ens late in their runs. The EPO ridge axis isn't optimal as it's a bit too far west but the Atl looks to offset some of that. Very gradient like pattern showing up and not that far away. Precip anomaly plots imply normal to above normal QPF from weeks 3-6

Weeks 3-4 look workable and the weekly trend is colder as you go out in time so weeks 5-6 are better than these:

Those are interesting looks.  Not a lot of good analogs to that.  Some similarities to 2014 at times.  January 94 is close but there is way more east based NAO help there.  Maybe that's enough to adjust the boundary 50 miles south and we get the epic run PA had that winter.  But that is very close to some pretty uneventful months too like January 1972, it would all depend how exactly how the TPV sets up and how much NAO help we get.  Add a favorable TPV and some -NAO and that is a very good look.  Absent those features and its generally a cold look but either dry or cutters.  

On another note of what might be ahead...as I suspected when I checked the analogs to the current look, while most didn't produce any snow at the time...almost all of them are from years where there was more persistent blocking episodes the remainder of the winter.  Some went on to have an epic period where we finally timed up the pac/atl and some were decent but not great years where we got some snow but things just didnt line up.  But not really many crap dud years in the list.  That is about what I suspected.  I would rather take a good look up top and hope the mid latitudes get right at some point than the other way around.  

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50 minutes ago, Bob Chill said:

I'm not sure there's a path to frozen even if it does climb the coast. Without some sort of northern stream interaction the mid levels are scorching all the way to Canada. 

There have certainly been times in the past where we were tracking a southern gulf low that never has a catalyst to take it North only to have the stj energy slow down and get picked up by a renegade northern jet shortwave. Doubt it happens here but who knows.

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

Like I said in banter earlier, enjoy your Christmas cheer around the fire pit. It should be perfect.

hopefully we are chasing something on christmas for early Jan but this is looking like a 2000-2001 40N winter with cold air and near misses

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Just now, Ji said:

hopefully we are chasing something on christmas for early Jan but this is looking like a 2000-2001 40N winter with cold air and near misses

Jeez you really went for the kill shot. That would be brutal.  I don’t think that’s the case. 

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So far in terms of 12z runs the storm signal is a shell of its former self vs what it was a few days ago. LR models are showing an improvement late Dec into early Jan with an EPO ridge further east which should dump cold air into the CONUS. But that's really about it. PNA and NAO looks like they go to crap really from the 10 day period out to the end of the run. I don't think a favorable pattern comes till around the 1st week of January or maybe even later. Thankfully the NAO doesn't go to crap until after 10 days so that's a good sign.

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