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January/February Mid/Long Range Disco IV: A New Hope


stormtracker
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It befuddles me how we can get a Nina-ish SER base but once there is any semblance of a cold push instead of the SER fighting and creating lift and overunning it just folds and the entire flow gets squashed and sheared/shredded in this progressive pattern. I know it's Nina, progressive is common but seeing zero lift with a H5 look that would suggest such is absolutely mind-boggling. 

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8 minutes ago, Chris78 said:

None of the moisture wants to play in the colder air.

Either it's shunted south or if it does comes north the thermal boundary races north and  the rain/snow line is up in NY. 

So F'ing frustrating. 

We haven’t sacrificed enough, need half the forum to go out of town or something 

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10 minutes ago, Chris78 said:

None of the moisture wants to play in the colder air.

Either it's shunted south or if it does comes north the thermal boundary races north and  the rain/snow line is up in NY. 

So F'ing frustrating. 

I don't ever remember anything like it. Though we have had the exact opposite in some years where whenever it can snow it does and will. So it's one of those balancing acts that nature likes to perform. This winter is just pathetic but there is only one way to go from here. 

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2 hours ago, CAPE said:

There was a bit more of a meridional component to it but guidance has incrementally backed off. Makes sense it would stay mostly across Canada once the -NAO look vanished.

What we are left with is flat, fast, west-east flow, with the NS vorticity strung out and separated from the (weak) vorticity impulses ejecting eastward out of the main energy in the SW. There has to be some sort of notable 'kink' in the flow to get moisture transport north into the cold(and dry) air.  We will see what happens when the main energy ejects east towards the end of the week- it looks like the Canadian trough/TPV digs more southward as it shifts east, but that might be problematic with timing and degree of cold in place.

There is still a path to a win.  My lament is that one of the reasons those wins are so few and far between is there are several factors lowering the odds. One example in this case coming up is the lack of penetration south of the boundary.  If we had a more expansive cold dome then the path to victory is simple. Root for a stronger SW to throw moisture over it. Simple. Easy. Now we need 10,000 things to go perfectly. We need the confluence to be even stronger to compensate for the fact we have no wiggle room with the cold but that is also more suppressive and so then we need an even stronger SW but to too strong because there is no wiggle room with the cold. We’re trying to thread a needle here on everything. 
 

As for the reasons why…the analogs I mentioned were all positive NAO periods. More recently we saw in 2015 that a tpv in eastern Canada with a +NAO can be a frigid result here!  Additionally in this case the NAO is more a result than a cause. The NAO trended + because the TPV trended north. We did kinda get head faked again. The tpv does get displaced and rotate across but that displacement is not nearly as severe as initially hinted. That second split I alluded to 4 days ago never happened. It fell apart on guidance, guess when, at about day 7 lol. So we got a less severe displacement which takes it into the NAO domain which causes the trend in the NAO. Instead of having the tpv under and the wave breaking pumping the NAO you end up with the opposite effect.  So here the NAO was a product of the cold not making it far enough south not the cause!  
 

Before anyone gets defensive and makes this about AGW I am not stating causality. And it’s difficult to quantify any correlation with any one event. There have always been examples of blocking fails. If you look at the scatter plot it -NAO -pna snowfall months I posted there was always some duds. So we can’t say “this NAO failed because of X” regardless of what x is. There is unpredictable variability in this.  Same with a tpv displacement. There are enough past fails that we can’t conclusively attribute this one to any specific thing.  And that’s not what I’m doing. I’m just noting the issues and logging them.  We can discuss the possible why is other appropriate threads!  
 


 


 

 

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44 minutes ago, Ralph Wiggum said:

It befuddles me how we can get a Nina-ish SER base but once there is any semblance of a cold push instead of the SER fighting and creating lift and overunning it just folds and the entire flow gets squashed and sheared/shredded in this progressive pattern. I know it's Nina, progressive is common but seeing zero lift with a H5 look that would suggest such is absolutely mind-boggling. 

That actually makes sense.  One of the reasons I’ve always been skeptical of this period having a high probability to produce. I’m trying to think how to articulate this. It’s like “showing your work” on a math problem you just do in your head.  But think of how the flow is affected by having a huge ridge at the mid levels right under us and the Tpv right on top.  The whole flow is compressed.  Shred factory!   That’s not the flow we want to get something to amplify near us. Ideally we want a split flow and a trough to cut across under the tpv. But I can’t because the SER is a beast so it tries to lift over the SER.  That only leaves 2 likely scenarios. It can’t lift and gets shredded. It can and cuts.  The in between scenario is the least likely and involved needed a thread the needle perfect balance between everything. 
 

Add on top of that what I referenced above that the cold lately isn’t even penetrating into the ridge as much as it usually does and it’s even more difficult because any weak boundary wave caused by these weaker vorts in the flow won’t have much frozen associated with them if the cold is mostly to the north of the zone of least resistance in the flow between the TPV and the SER.  
 

When I play out this steam interaction in my head the paths to win seem way harder to imagine than the fails. As @Bob Chill likes to say it’s complicated and we don’t do complicated well. 

 

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56 minutes ago, LeesburgWx said:

Have the spring threads opened up yet? This is pathetic

I ordered a new cold frame for my garden that should arrive today.  Clearly winter is a lost cause this year so at least I might as well start growing lettuce.  Maybe that'll be enough to turn the tides and usher in record cold and snow.  

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