psuhoffman

March 1960 was another example of a post SSW cold enso poleward Pac ridge blocking pattern where a western trough elongated east and that lead to one of the snowiest months in mid Atlantic history. In March no less. If the block is firm enough to suppress the SE ridge it’s a very good pattern.

The block has erected quite the cold signature

That profile is very 2014. Makes sense. The pac ridge was further east in 2014 with some ridging in the AO domain but not much NAO. This year if that projected pattern comes to pass the EPO is further west but with more NAO blocking. Those differences offset each other and you end up with a similar pattern.

The GEFS really did lead the way wrt the pattern progression....it started going hog with the blocking the last few days...really ramped it up at 6z and everything else fell in line with it today.

First I am totally fine with constructive criticism! This is an open forum and anyone is free to challenge and disagree with anything I say and hopefully everyone knows that. But second there is a WHY that matters behind the what (no precip). What I’ve suspected and been saying and HM just confirmed is that one of the big problems we’ve had getting any of the southern waves to amplify in this split flow is the lack of cold. I know they seems counterintuitive but cold doesn’t suppress the flow does. Now there is a correlation because a colder airmass will press the baroclinic zone (tighter temperature gradient between warm/cold) south and the suppressive flow of the NS will likely be further south. But without enough cold there wasn’t enough temperature gradient to fuel the storms. I don’t want to start an atmospheric physics class so I’ll grossly simplify this but it’s that temperature gradient (baroclinicity) that fuels our mid latitude storms. Without cold there is less gradient and less potential energy for storms. Result= weak POS systems along the weak thermal boundary in the south that don’t amplify and come north. The systems that did come north were weak and during periods of ridging when the weak temp boundary came north. But even then they were too weak to initiate what we needed. That perfect track storm back around New Years could have worked if it amplified more. But it was pathetic so we got light rain (talking about the second wave) . Had there been more cold in this pattern the results likely would have been less dry. Looking ahead with a more canonical Nina look in the pac we don’t want too much cold and suppression. But that -NAO -pna -epo look is intriguing. The level of blocking being shown now would suppress the SE ridge but the -pna would create a SW to NE flow towards us. That’s potentially a fun pattern.

No that look is great. If that’s what Jan 21 actually looks like I suspect end of Jan early Feb produces. But lots of “if” there.

Nothing is a problem there just need to wait. This first tanking of the NAO failed due to lack of cold. The next tanking comes around the 20. If cold gets involved after that should hold potential.

Not if you were looking at h5. It split the trough leaving the southern part behind. A non phased split solution won’t work with the NS we’re dealing with. Need phasing to pump ridging otherwise the NS will keep racing west to east squashing anything. Once it split and the NS raced ahead it was dead. The shred factory would get it.

I’ll get a grip...

@leesburg 04 I think sometimes when I’m carrying on multiple different streams of thought in here they get confused. I’m really carrying on 3 distinctly independent conversations. 1. lamenting the expected but still disappointing fail of the split flow blocking pattern. We saw the signs that the antecedent airmass wasn’t going to work but there was some hope maybe given a pretty excellent longwave pattern we could get lucky. We didn’t. But there is also the fact that historically that pattern isn’t cold but it’s often been colder and just cool enough to get a better outcome. This year was pretty warm compared to analogs to that look. It’s worth noting that at least. 2. the degradation of the first discreet threat period (Jan 15-20) of what looks to be a colder N American regime is losing potential. It’s not a total pattern fail but there is a bit of MC forcing spike and the initial cold press goes west. We might even pop a ridge initially before the cold spreads east. It’s a see saw effect. Put a dump of cold west without enough cold already in the pattern east and...up goes our side. Over time the see saw will balance provided the blocking remains. 3. Longer term Jan into Feb still looks promising though. The blocking continues to look to have legs and we get cold back into our source regions. HM pointed out in another post in that thread I shared some of that the progression of the pattern after the initial maritime continent forcing could be favorable because we’re already in a blocking regime and cold will be pressing back into our source regions. We should have a period of -EPO -NAO late January into Feb. That’s hopeful. And I totally get the frustration and wanting to just be like “why bother” but I’m just breaking down where things stand now.

DT isn’t even here anymore to hear it.

Yes but wasn’t that always our target too? Although i think we were hopeful maybe starting around the 15th but the last week of January looking more likely now. But my point is even though we kinda expected it to fail...it’s still a fail right?

I don’t like to assume an interpretation of someone else’s thoughts. That’s possible but I do know weeks ago he was implying he felt optimistic for January snowfall so I read it to be more about the “total” part. He takes a much more global view then IMBY. Parts of the southern plains and Deep South have had one of their snowiest winters in forever. But again...I don’t want to put any words in anyone else’s mouth.

Confirmation of what we’ve been saying for a while.

HM still seems hopeful.

We need to get cold into the pattern. The pac still looks to be more favorable to get cold back on our side soon. That’s delayed here because the initial cold goes west first but if the blocking is still there it will expand east after. If we can hold onto the blocking after the cold gets into the pattern we will have more luck. The fail option is if the blocking breaks down then Feb will end up cold west ridge east because the epo ridge is too far west absent blocking. Epo alone doesn’t work it needs other factors working in concert.

Past 150 is dangerous. I’ve been saying the globals seem to hone in on synoptic level details starting around 150. Those threats evaporated right as we reached that threshold.

By bar is somewhere between 12” and some random flakes. Also I’m way more willing to be interested in a minor snowfall within 48 hours. But investing time tracking a clipper or some snow showers no.

Some pity flakes maybe. A real snowstorm...ehh. You should talk to losetoe6

@CAPE the eps actually fully caved to the GEFS pattern progression in the long range. But both have now picked up on something that mutes our opportunity before that. It makes sense in hindsight. After the poleward pac ridge goes up and the initial dump of true cold goes into the west...a ridge will pop as response in the east. At that time there isn’t enough cold in the east yet for that see saw equation to end well. It also doesn’t help that the NAO ridge still is just an extension of the WAR at that time and hasn’t retrogrades and cut off enough yet to fully resist the SE ridge. But with the blocking that cold starts to bleed east and eventually we get a pattern that can work. The only problem there is that’s a more typical Nina pac and the STJ will be totally cut off. So the fear is if the NS doesn’t gain enough depth it’s a dry NW flow pattern and we watch New England get late developing Miller Bs. It has worked before though. March 2018 was a poleward pac ridge -NAO pattern. But remember that was frustrating at times with 2 miller b miss big New England storms before we finally got our snowstorm. January 2011 had a poleward PAC ridge buy it stayed centered just off the west coast and never fully pulled back too far. Feb 2006 kinda worked...we got one big snow but we waited around most of the month with a great block waiting for that one southern wave to come along. That general pattern has lead to snowstorms but it can be really frustrating if the NS is dominant and nothing amplifies.

Yes or if the block is really flexing crazy transfers from the Midwest to the coast.

It degraded significantly since then. The trough doesn’t have enough depth and it’s all NS now