Stormchaserchuck1

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.

Pacific definitely has more pattern correlation in N. America, I think. Another thing is the orientation of the PNA. When it's a 40N, probably more hostile than 45-50N. 45N, it runs with waves that are more N/S, and can be broken by the time it's here. 40N ridges are pretty uniform.. it would probably be hard for us to get snow with a strong N. Pacific 40N ridge.

Maybe -EPO's are 2-4" inch events, because it's a Canadian cold pattern.. the cold air comes south from Canada, and the jet stream is essentially NW to SE, favoring clippers or storms moving W -> E, vs from the south.

Maybe it's common for a +EPO to progress into a GOA Low because they are almost the same thing? Big difference though in the downstream pattern, every degree of latitude difference there is huge! Edit: I don't know.. if you are cold a week before that's not very +epo. I just know that in the mid-latitudes over the Pacific and Atlantic, you have your strongest global anomalies for our snowstorm composite.

That's actually a pretty good -WPO surprisingly and also surprisingly because it correlates with Canada, neutral 500mb over and NE of Alaska. I'd like to see the +EPO snowstorm composite sometime if you ever see it, because a true +EPO, with the strongest anomaly in the Northern Hemisphere over Alaska... there is pretty much almost no chance of snow in that pattern.

PNA has a big precip correlation like the NAO. It's actually equal to temps. So if we are +0.5 in -PNA (75% chance of above average temps), we are also +0.5 precip (75% chance of above average precip). You can see how if other things are favorable, that could possibly align with more snow... but I would say in the 1960s we not only had some -NAO blocks, but there was a much stronger relative [underneath] mid level trough... maybe that was from -AMO -AMO ibb.co/bR3LvKW+AMO ibb.co/KctZCPm-AMO ibb.co/wKX4YCC+AMO ibb.co/sFSwm0j Thanks for your input about our discussions.. like I said before, you discuss these things and do research on it.. that's more than people can ask for. The thing I like about +PNA is it has lower pressure correlation on the coast, despite being 75/25 drier. So +PNA in the Winter can be more fun, because it's more associated with stronger low pressure and windstorms. -PNA's are just overrunning events.. I'm surprised you have 13 cases associated with +EPO. I think that's in part because of how it's calculated. A trough in the Gulf of Alaska is actually a BIG factor in East coast snowstorms.. that and a 50/50 low. 8"+ composite has like a -120dm anomaly in the Gulf of Alaska... that in some cases is called +EPO. I consider the EPO to be more a 500mb over Alaska and north of, and sometimes going NE Of Alaska into NW Canada and the Arctic circle. The CPC calculates the EPO much further south. Some blizzards may have technically had +EPO because of this, but when I think of +EPO, that pattern is shut the blinds, blowout, mid Winter 50s and 60s. I think the overlap between PNA/EPO is where the weakness in your snow data is. I see your clear cut correlation with NAO and AO in your data. Half of the NAO is calculated in the mid latitudes. Sometimes the mid latitude will be cold, and there will be none or a weak High pressure over top of it.. that's called a -NAO. We had a lot of that in the 1960s. We've had the opposite lately. NAO remember is North Atlantic sea level pressure differences between ~Iceland and ~The Azores. If there is neutral over the Azores, that's a 0 to half the NAO index. And of course, that mid-latitude trough extends to us.. so by default us having a trough is actually more of a -NAO pattern. See? If you separate out the high latitude High pressures it's probably a weaker correlation. We haven't had those mid latitude troughs lately, so the CPC has said 41/46 Winter months since 2013 have been +NAO (16/16 NAO cases monthly >1.11 in that time have all been positive!)!

Light rain has started here, not snow and sleet like models had the last few days.. started as rain.

Can you believe the Chiefs are favored? I have a rule, don't bet against Mahomes, but he didn't even make the Pro bowl this year..

I think the Eagles will win, as they have a much better team. Maybe even by 2 scores.

I think -EPO/+NAO would produce a 30" or 40" Winter, because NAO is strongly correlated to precip, and the positive phase has 3x more precip than negative phase (+0.50 correlation vs -0.50 correlation, is that 3x?)! EPO is neutral precip and the coldest pattern of all indexes.. so with the EPO having slightly more cold correlation than NAO, we would be below average temps with above average precip in that pattern! Only thing is EPO is loosely related to H5, so some of the cold precip could be ice. I also think it's just a general point - mid latitude cold, not necessarily related to upper latitude High pressure, is the snow pattern. So us losing mid latitude cold is the generality that is correlating with less snow. It doesn't always have to stack.

PNA might be a little underrated.. In your maps, its signal beats out the NAO and AO. Also, for a 90N block to work, you should be at 45N. So the composite also shows 80N blocking (northern Alaska/Greenland) as the strongest signal for 40N here... something to keep in mind because this coming block is right up over the Arctic circle. But +PNA is strong, and the 8-year period is most -PNA on record by 150% over any #2 (at least for Feb-March)! Greenland blocking recently has disconnected somewhat, but when we have a strong +PNA/-EPO pattern it generally doesn't disconnect (I know we had -epo in Dec 2022 and March 2023, but that's the only time it didn't correlate with cold). If you believe the CPC, it's also been +NAO in the Winter something like 41/46 Winter months since 2013.. and record -PNA.. it's no surprise our snowfall is record low (although I think they base a lot of NAO calculation on mid-latitudes - the ability for a Greenland ridge/block to produce a trough underneath of it)!

About AO/NAO being snow signals.. If you base them solely on High pressure, I don't think so. The mid latitude cold is a stronger pattern. You see -50 anomaly in the Pacific and <-40dm anomaly off of western Europe, but the whole northern latitude AO/NAO blocking only reaches +35dm. A lot of times when we are talking about the NAO, we are talking about a Greenland block. But the mid latitude needing to be cold (50/50 low, +PNA) is actually more important, according to those maps.

Yeah but it happened. We had a real strong -EPO that Winter. EPO is more of a rare pattern, and you see it usually run in 7-12 day cycles vs longer periods, so you generally don't get it in a full Winter composite (a lot of + and - periods in a Winter). It wasn't like some tropical pattern that lead to an anomalous snowfall that Winter.. it was Pacific driven cold, legit imo.

Yeah, but include 2014 because there's no reason why not to include it.. +NAO/-EPO is actually a pattern that has happened in tandem more since 2013.. I'm surprised we don't get more -EPO driven snow, maybe there's a lot of ice instead. Here's the 10 analogs you came up with This doesn't scream blocking to me. This screams mid latitude cold. Last year I ran a composite of December's before DCA's most snowy Winter.. in those composites 90% of the N. Hemisphere was below average in December. This isn't a -NAO signal as much as general mid-latitude trough/below average.. -NAO is the 3rd strongest anomaly in that ^ map. A cold trough over western Europe is actually a greater anomaly by almost double! Wow (in the upper latitudes there is more volatility, so that's even more impressive)! +PNA too.. And the Arctic circle/North Pole might actually be too far north for a block to correlate with snow (I guess unless you're at 45N).

I think they have it included. I was wondering about the string of High pressures, and if it was going to break down allowing storms to track more north again.. so far that looks to be the case. It will be hard to have so many rainstorms though with the AO at -4 and nothing really unfavorable in the Pacific/Atlantic mid latitudes. For the data collected on -AO being our snowstorm pattern.. know that a ridge at 90N is rare. Usually the NAO/AO overlap, and they are just talking about Greenland block.. I wonder if the Arctic circle is actually too far north to have substantial effect on our precip type.

What do you mean, you think the models are warm biased because of Nina?

That's called a -AO. NAO is a North Atlantic sea-level pressure measurement.

+PNA, which is starting to show up in the long range, favors lower pressure on the coast.. like that 968mb frame on the LR GFS. Hopefully it holds.. it's going against the 7-year seasonal trend For learning, -EPO is always an ice possibility pattern.. non-neg EPO is rain/snow.

It's an active pattern in the medium range.. so much for all that drought stuff everyone was going with after the dry Summer.

Seems like you found your tool. I was saying the 500mb pattern didn't look good when it was far out, but everything came together to match the snow output.