Stormchaserchuck1

They look +NAO to me. Just confirms that our best snowstorms happen with favorable Pacific and +NAO (that's why negative heading to neutral is so strong.. -NAO is actually a very dry pattern).

NAM has had the low near Detroit.. Gfs was much furth south. Still some spread, but fwiw the 0z Hrr looked like the 18z NAM.

+NAO is a wetter pattern.. so a slightly displaced NE 50/50 low can correlate with storms.. and snowstorms if the Pacific is favorable. The pattern looks somewhat like 13-14 and 14-15, with the monster +NAO those Winter's just south this time and +ridging over Greenland and AO zone. The important point about 50/50 low though is where it is when storms are coming.. because it shifts around a lot.. is it a south-based +NAO for the storm, or an ideal 50/50 low? I was just pointing out that the map brooklynwx posted, it's not a slam dunk for arctic air.. an Atlantic SLP gradient in that spot actually has a slight correlation with SE ridge... doesn't mean it can't snow. Again, +NAO like that one, with a favorable Pacific is a snow pattern. precip is +0.50 correlated to +NAO, which in this case may slightly overlap 50/50 low some of the time.

0z Hrr.. then the 2nd storm is trending toward rain

Be aware of this pattern though... But the Pacific side is favorable, so it should be cold enough

It does moderate a little at 84hr, with the 925mb low up near Lake Eerie. Rain except in the mountains.

CAD is holding surprisingly strong for the storm after it.

It's also a bit odd to have another strong storm right on its tail like that.. there is usually more spacing between waves.

We are failing though because there is +NAO tendency this season. I posted it on the last page, this connection is a little warmer. Because we are at 40N, south of 45N, what happens in the mid-latitudes is actually more important for us than what happens at 90N.

NAM is north but it is the horrible NAM.

Block at 90N has only sustained though for more than a few days maybe 4-7 times since 1948 (I've gone through and looked at the data on daily - came up with 7 main index regions in the N. Hemisphere, and North Pole was not one of them). It's because of this a super strong low is now projected to form just south of Greenland. It's too bad it's not 5 degrees south, because that would have been an awesome 50/50 low. But the H5 change between projected time and day-of is not big, because the CPC calculates NAO error, and it has like a 90% chance in that graph of verifying positive. It's because of this slight displacement north of the 50/50 that we will now have a SE ridge! Unfortunate, but I'm saying there is a reason in this case for the -AO to link up with a SE ridge.. it's a little too far north. Now, 2017-2023, there were a lot of anomalous SE ridge's in that time (especially 22-23).

It's probably more about the Pacific pattern being good vs neutral/not.

I know you all like the Hrr at 48hr.. big storm

Before we get 1" of new snow! I would have actually favored more of a Weak Nina late season look, because I've correlated the ENSO subsurface with Pacific PNA pattern, and it actually came back with high forecasting predictability. But this season is different.. a good case study! A week ago, I wasn't thinking it would be as favorable as this.... I'm still real curious though to see if we can get solid cold in the 2nd half of Winter.. I do think that as the average temperature starts to increase, there is tendency of late to keep us warm.

I think for future reference, it's a good research to do where the block is. A lot of AO data overlaps with NAO, and a lot of times it's a Greenland block that is -AO.. but this time it's over the North Pole, so that's actually a little different. This is why I like to look at raw 500mb maps vs the actual index numbers, although you could probably look at AO vs NAO and get a good analog system from that.

Yeah I think it's a pretty legit shot at something good. Hopefully storm systems keep being as strong as modeled. If that Pacific pattern that is currently modeled holds, watch out... It's a good observation too that a 90N block correlates with cold at 45N, but further south at 40N there could be a tropical ridge tendency as the 3rd wave down. Today it has evolved to look like that because of south-based +NAO though.

I actually like that timeframe because there is a -EPO. It's a nice Polar connection of ridging from AO to EPO, and maybe even +PNA. If 500mb doesn't change, it should trend more wintry for the Mid Atlantic. But it's still 11 days away, but I really do especially like that -EPO modeled right now. That Day 7 storm though, is really +NAO. That low just south of Greenland gets up to -500dm. That's strong positive! It's a rare case of super -AO and super +NAO at the same time! Edit: I just saw for the Day 11 storm, models keep holding onto the south-based +NAO throughout their run. Just know that -EPO/+NAO is more ice, but +PNA/-EPO/+NAO is more snow.

See how the south-based +NAO aligns with a slight SE ridge? It's too bad the block isn't a little further south, or that N. Atlantic low would have been in the perfect 50/50 spot, and we have all this moisture/storm systems.. would have been a big one. We needed that Polar block at 80N, not 90N.

It's probably partly because the storm today is going way north.

Looks like a March storm

Huge storm. 1042mb High in SE Canada. Very interesting

I actually drove down from MD to FL this Summer, and was admiring how sensitive the climate and animals were, saying "it can snow here!". I couldn't believe places in GA never would see snow.. a stupid 12 hour drive south. Seems like every mile it's a different type of vegetation. I think it has actually snowed in the Florida keys before...

Maybe it really is about the PNA, and our chances of seeing +PNA again. The thing is.. the mid-latitude trough (+pna) has also not happened in the Atlantic, even with -NAO a lot of the time... so is there a bigger global pattern for warm mid latitudes, or can we connect to PNA cycle? This Winter is hopeful because despite a Fall PDO of -3.88, and Weak La Nina (even in the subsurface, which I've connected with the pattern), +PNA has prevailed. -PNA has actually happened none so far. I think since Nov 30, the lowest the CPC PNA index got to on the daily was -0.1, and it's back >+1.0 in the medium/long range again. But here's our cold, and real legit cold... with +PNA. I think that pattern could work.

By the way, this looks like snow to me

Something about the temperate base state isn't anomalous though.. there's something to it, driven by a factor I believe that is something specific vs global warming. Just look at a week ago, it was heavy dry/fluffy snow in Pensacola with a temp of 24F. There is something somewhere that is like a warm layer underneath.. that's what I was trying to connect to the 2nd half of Winter -PNA's, but that's not what it is.. I don't think it's AMO either, but we have seen glimpses of Winter. Last year in the Chiefs home playoff game, the windchill was -30F.