December Medium/Long Range Discussion

[Ji]

This winter is starting to remind me of 01-02 where everything was delayed and denied till we looked up and it was April

[BTRWx's Thanks Giving]

19 minutes ago, Bob Chill said:

We need to hope the gefs/geps win this model war. I'm assuming the eps is following the mjo and that's not always a 1:1 correlation. If this is where we are heading during the holiday week it will be a bit of a bummer....

Learn the language of the MJO and you won't be disappointed when it doesn't snow.

[Bob Chill]

5 minutes ago, Ji said:

This winter is starting to remind me of 01-02 where everything was delayed and denied till we looked up and it was April

A little early for that. We'll know in 2 weeks tho

[showmethesnow]

Here's a pretty good example of the EPS' bias when it comes to over dumping energy into the southwest in the extended.

Below we have the 12Z from two days ago for Christmas Eve. Notice the distinct trough and lower heights in the southwest as well as the higher heights popping in response in the east.

 

Now the EPS has had fits and starts since but it has eventually moved to this look at the same time frame on the latest run. Notice we see the trough is shifted eastward with ridging building just behind it up the west coast. The ridging on the east coast has shifted over the ocean in response to the trough shift.

 

Now we are back to the run 2 days ago for the day after Christmas. Notice we are seeing strong negative heights in the west with strong higher heights in the east.

 

Now this is the latest run for that time period. Notice the heights in both the west and the east are much weaker. A sign that the EPS is moving awat from dumping a lot of energy in the west.

 

[jaydreb]

Ugh that 18z GFS run was just plain ugly.  I know it’s just an ops run but man...

[AfewUniversesBelowNormal]

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

Christmas! We need a SSW event or something. Chuck?

This panel is not all bad, but you can see whats coming immediately after- trough dumping in the west and more ridging in the east.

 

The Stratosphere warming is kind of exciting. Does anyone know if it's happenening at 90N (i've seen maps of 50-80N). I do think it doesn't match the pattern right now, so the lag for a Strat warming -NAO is 25-30 days at this time of the year so a late January/early February -NAO might be the main thing, I think this is why LR models are going back and forth about a -NAO during the time (7-15 days). I would love it to happen, although I hate that it's fitting a maze-like Winter pattern (was hoping it would be -AO/+PNA all winter long),This is usually wet snow vs dry /blowing snow.

[aldie 22]

1 hour ago, Ji said:

This winter is starting to remind me of 01-02 where everything was delayed and denied till we looked up and it was April

You had to do the paper interview didn't you. Had to say big winter coming in the interview didn't you. I know who I'm blaming 

[tplbge]

2 hours ago, leesburg 04 said:

You had to do the paper interview didn't you. Had to say big winter coming in the interview didn't you. I know who I'm blaming 

Nah.   It was me.  I had to move north for better snows.  What happens?  Historic storm hits South.

[Bob Chill]

Gfs trying for a triple phaser christmas present. Not there yet but 10 days plenty of time to adjust. 

Eta: triple phaser with a neg nao 

[Maestrobjwa]

3 minutes ago, Bob Chill said:

Gfs trying for a triple phaser christmas present. Not there yet but 10 days plenty of time to adjust. 

Eta: triple phaser with a neg nao 

It's been hinting at some type of precipitation of some sort around that period for the last couple days, right?

[MountainGeek]

46 minutes ago, Bob Chill said:

Gfs trying for a triple phaser christmas present. Not there yet but 10 days plenty of time to adjust. 

Eta: triple phaser with a neg nao 

 

Lock it in....setting my bar at a 48" BECS for Christmas. Anything less and I'm planting cactus in my backyard like @EastCoast NPZ.

I do like seeing somewhat of a consistent hint of precip in that timeframe....and we may not be that far away from having something inside 10 days to track.

[yoda]

FV3 continues with its coastal runner idea for Christmas... rain for all up and down the Eastern Seaboard for the big cities 

[MountainGeek]

Still needs a bit of work, but we have time. I'd take my chances if we can get a storm with cold air not too far away....we can work on convincing the low to track in a more favorable spot. At least the GFS and FV3 seem to understand we need an event to happen around Christmas. 

Besides, no chance anything changes over the next 12 days....

[showmethesnow]

The overnight EPS has firmly moved away from the idea of dumping the NS into the weakness/troughing we have set up pre-Christmas as for the most part the NS is allowed to progress eastward. That includes the initial dump we were seeing as well as the secondary that was showing up post Christmas. Thus the ridging/higher heights in the east are very much weakened compared to past runs as they are responding to the weaker feature that sets up in the southwest vs. the the much stronger in past runs. This is a good thing as seen below.

 

Here is yesterdays heights map. Notice the trough is located in the SW and encompasses both the southern stream and the northern stream. This is a strong feature so we are seeing the typical response in the east with strong heights building.

 

 

And this is the response we are seeing with the temps through the CONUS from the above map. Notice we have a -EPO that is driving the NS down from the arctic regions but the flow for the most part is into the weakness in the SW. This flow will then pull eastward a bit before it pulls back north into Canada bypassing the eastern US. So we are seeing strong cold anomalies in the west vs. the strong warm anomalies induced by the higher heights in the east. As I have mentioned time and again we do not want to see this play out. This evolution would wreck the pattern where it would take time to recover potentially a good deal of time.

 

 

Now the EPS has been back and forth with the long range pattern but despite that it has slowly been moving to the look I have favored for awhile which can be seen below from the overnight run. Notice that we see a much weaker SW feature. We still see the troughing down there but we are not seeing full latitude trough that we were seeing in the previous example. That is because the NS has bypassed that SW feature for the most part as can be evidenced by the NS trough we see set up in the central portions of the US. Now with the weakened SW feature we are still seeing a response of higher heights in the east but they are much weaker as would be expected. Now typically we wouldn't want to see higher heights in the east even those in a weakened state. But in this case and setup we prefer to see some weak height builds especially to our south and east (SE ridging). There are two major reasons for this. For one it helps to bump up the sub-tropical jet in the east putting it in play for us. And two it helps to mitigate the southward push of the northern stream induced by the -EPO and/or -EPO/+PNA ridge. Without those higher heights in the east the NS can quite often dominate the pattern and be suppressive in the east.

 

 

Now look at what a difference the above set up has for temps. We are seeing colder temps through the whole of the northern US as the NS drops south and then expends its energy moving eastward instead of dropping south. Now without the weakened higher heights in the east we would more then likely see the flow take on a more southeasterly track through the CONUS which would probably end up suppressive for those of us in the east. I will also mention that I believe the cold being shown is under done at this point. The setup argues for colder anomalies through the northern US but the models quite often times underplay that at range. If in fact the EPS holds onto this general setup we could probably expect to see a deepening of the cold on future runs.

 

 

 

One last thing. I still like the potential for right around Christmas and that hasn't wavered. Short of a major NS dump into the SW I have thought the pattern argues for a system impacting in the east at this time. At this point whether it is white or wet is still in the air. It really will come down to the evolution of any potential system, whether there is any NS involvement, and how cooperative temps are at that point. I will say though that looking at the current setup I do believe that the models are underplaying the cold through that time.

Here is some eye candy (overnight EPS control run) before I go. 

 

 

[aldie 22]

Who knows what will happen but if somehow there is snow falling on or around Christmas day in my front yard then December is a win in my book.

[PDIII]

6 hours ago, Bob Chill said:

Gfs trying for a triple phaser christmas present. Not there yet but 10 days plenty of time to adjust. 

Eta: triple phaser with a neg nao 

Thanks Bob. You really are the one that gives us hope around here.

[aldie 22]

8 minutes ago, PDIII said:

Thanks Bob. You really are the one that gives us hope around here.

Have you read Bob for the last week? 

[showmethesnow]

Very nice bump up on the snowfall means through the extended on the GEFS. 3" mean is now just NW of DC/Balt. 

[PDIII]

13 minutes ago, leesburg 04 said:

Have you read Bob for the last week? 

Not really.. I have been stayinig away.. I am not really expecting anything until January.  It has been way too cold... it is gonna flip at some point and we will have a week or two in the 50s with periodic rain storms.. We wasted a really good pattern and now we need to pay for it.

[CAPE]

5 minutes ago, showmethesnow said:

Very nice bump up on the snowfall means through the extended on the GEFS. 3" mean is now just NW of DC/Balt. 

Its happening! (again). Until it isn't.

In all seriousness, the overnight runs were encouraging, especially seeing the EPS move away from a full dump western trough. Now lets see if it manages to hold/improve on the better look in the next few runs, or if it steps back yet again.

[showmethesnow]

06Z GEFS has also backed off on its secondary NS dump into the southwest as seen on a couple of previous runs. Also seeing better indications that the GEFS is now picking up on a possible southern low/coastal through Christmas. Temps through this period of time are several degrees colder then the previous run and would be more then sufficient for snow through our region with any possible system. Really am liking the look we are starting to see with the GEFS around Christmas and it suggests that we might see another system impacting the region just a couple days later as well.

[WxUSAF]

Yeah it’s coming into focus that the 24-26th is a legit threat window for a southern stream coastal. Trick is cold air availability.  The PAC puke airmass ain’t going to cut it even with a perfect track. Need something to flush that air out and bring in some sort of polar airmass. Probably the ideal scenario is a northern stream low passes to our north, flushes in some good air, then hangs around 50/50 while the souther shortwave tracks below us. 

[CAPE]

Cohen is all jacked up over major SPV discombobulation. He can smell victory!

[North Balti Zen]

21 minutes ago, WxUSAF said:

Yeah it’s coming into focus that the 24-26th is a legit threat window for a southern stream coastal. Trick is cold air availability.  The PAC puke airmass ain’t going to cut it even with a perfect track. Need something to flush that air out and bring in some sort of polar airmass. Probably the ideal scenario is a northern stream low passes to our north, flushes in some good air, then hangs around 50/50 while the souther shortwave tracks below us. 

Any chance the rainer this weekend ends up a block to usher cold air back in?

[WxUSAF]

Just now, North Balti Zen said:

Any chance the rainer this weekend ends up a block to usher cold air back in?

It doesn’t look like it. We need something in the 21st-23rd window to flush out the airmass if we want cold air around. It’s very possible that the event we’re hoping for ends up being that. There’s a reason that we do better as good patterns break down or reload rather than as they arrive. But if it’s a good track, we don’t need excessive help, just some modified polar air brought in from some northern stream front.

[WxUSAF]

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

Cohen is all jacked up over major SPV discombobulation. He can smell victory!

Smell that? You smell that? Ozone son. I love the smell of ozone in the morning. Smells like victory.

[EastCoast NPZ]

1 hour ago, leesburg 04 said:

Who knows what will happen but if somehow there is snow falling on or around Christmas day in my front yard then December is a win in my book.

Any accumulating snow on Christmas Eve or Day and all is forgiven.  If not, **** this winter.

[pasnownut]

30 minutes ago, WxUSAF said:

It doesn’t look like it. We need something in the 21st-23rd window to flush out the airmass if we want cold air around. It’s very possible that the event we’re hoping for ends up being that. There’s a reason that we do better as good patterns break down or reload rather than as they arrive. But if it’s a good track, we don’t need excessive help, just some modified polar air brought in from some northern stream front.

Was just going to respond until i read a little further below and saw this.  Yeah its more likely to help tweak the NS upper air pattern for what happens beyond as we approach Christmas.

Been bouncing around on the ops/Ens and have moved back another step from the ledge.  EPS bias just needed to have a little more time to adjust....I hope.  Even the Op runs way out are starting to take the look of overrunning.  Just fine by me.  Reasonable progression and NO TORCH FOR CHRISTMAS.  Win win for me.

Verbatim, the 6z GFS isnt far from stuffing stockings w/ snow for N/W locals. 

 

[jackb979]

Definitely will be a warm-up between now and Christmas it looks like. But According to the FV3, that pattern won't be locked in. Still over 10 days out but FV3 has been pretty consistently bringing the cold back at/right after Christmas. And just for kicks, I'll post the end of the Fv3 run so grain of salt here (but i will say Fv3 has been consistent with the cold returning towards the end of the month too)

Fingers crossed

 

[WxUSAF]

Long way out, but I'll take it for now.  What we want to see though is that weakness in the Lakes go away (which indicates some northern stream lows that would muck up our temps) and an increase in high pressure in that same area between the Lakes/Quebec/New England.