Stormchaserchuck1

Sub 5100dm over the Artic circle tomorrow! Areas of cold 500mb >60N continues to be a theme for the warm season since May 2024, and May this year. I say for cold Winter prospects, give me cold upper latitude 500mb earlier in the year. I think it correlates to more -EPO conditions down the road. Hopefully the trend of cold 500mb continues in the Fall. It shut off after September last year, and in the Fall of the last several years.

Pretty cool to watch the N. Pacific warm pool shift north with the Summer pattern. It's aligned right now with the Hadley/mid-latitude Cell.

^Winter NAO prediction based on May-Sept N. Atlantic SSTAs will probably come in weakly positive. Add to it that we are in the period of 0 to +4 years after a Solar Max, which has a +0.2 Winter NAO correlation, or 55% of the time. Then the NAO has run positive 6 straight months, and the AO has run positive 5 straight months.. that rolls forward to a +0.2 Winter +NAO correlation. All-in-all, that gives us about a +0.3-4 correlation right now for +NAO Winter (DJFM), or 60-62% chance of happening, based on those 3 indicators. Because of the decadal cycle, and 83% of Winter months have been +NAO since 11-12, I would say the current odds are more like 65% chance it is a +NAO Winter.

18-19 and 20-21 through 22-23 -NAO's were really not getting cold at all. The last 2 Winters, there has been cold under -NAO patterns in the east, and the Mid Atlantic has done better in those times.

Down below 5190dm over the Arctic circle Aug 22-25. It's doing exactly what that +AO roll-forward showed, in the exact location, albeit a few months early. I thought this was impressive because the Polar Vortex was 2000 miles from where the base +AO period had negative H5.

Down below 5190dm over the Arctic circle Aug 22-25

Thursday I will have been 75 or under for a high 4 straight days. Yesterday it didn't get out of the 60s. Hard to believe it won't be cold enough to snow in the Winter unless we stumble into a really bad upper latitude pattern. The cold next week (more days with highs in the 70s) is largely -EPO driven. Aug -EPO is actually a colder-Earth pattern, when you roll it forward into Jan-Feb the correlations are pretty high on the below average side generally I was stressing the cold H5 over Greenland May-July. It's moderated now, but has been proceeded with some cooler indicator conditions. Last year there was cold H5 over Greenland May-Sept, this moderated in the Fall.. this year it's the same thing but maybe 1 month early on the moderation. Give me cold H5 earlier in the year, I don't care if it's +NAO (unless it's the Winter).

A big problem has been the upper latitude pattern. This big ridge in the N. Pacific is -PNA Here's the Winter sea-level pressure pattern with PNA (map is default positive, so what's happened lately is opposite of this map) ^Notice the low SLP off the east coast. -0.3 is pretty significant correlation. We've been seeing -PNA (North Pacific pattern), so there has been more tendency downstream for High pressure along the east coast and off the coast. That's just the Pacific.. in the Atlantic since 2011-2012, 83% of the Winter months have had +NAO! In that time monthly NAO readings of >1.11 have been positive 18-0. Here's the SLP correlation with NAO, this map is default positive so in +NAO, like we have seen lately, it is like this Again, very High pressure correlation. Add the Pacific and Atlantic upper latitude patterns together and you have 5x more likely to have east coast, or off the east coast, High pressure vs Low pressure in the Winter months. That's the pattern we've been in since 2011-2012 and more so since 2016-2017. A core reason for this is the decadal La Nina state that has been in place since 1997-1998. Some say -PDO, but the Hadley Cells are flexed in the southern Hemisphere too so it's been more Nino 3.4 driven, imo. Atlantic NAO is a decadal cycle, since the 1800s there have been 4 swings between positive and negative. They usually last 30-50 years at a time. We have been in the middle of a +NAO decadal cycle. Of course the jet stream is moving north with global warming, but it's been bad timing with regard to long term global pattern fluctuations.

^It seems the Euro ensembles are good at those long range forecasted hurricane numbers. I remember in the 2nd half of last season they had 5x average, and we sure did have an active period.

I started keeping a weather journal in Sept 2002. I was surprised looking back at it, how many days there was snow in October. It seems those massive Winters hit early, consistently, and end late. My last snowfall in 03 was in early May, and it snowed over 100" that Winter. The odds of a major one is probably 5:1 less this Winter, while closer to average doesn't have as bad odds.. so yeah, October might come in a little warm (The PDO's top correlation month of the year is Oct).

Hard to believe we ever had -AMO, but for 100 years the Atlantic did average 9 named storms per year.. We are already on number 5 with moderately above average SSTAs. This is the 3rd year in a row with top 1% Rapid Intensification where a certain storm jumped over 12-18 hours: 2023 was Lee 2024 was Milton 2025 Erin I mean like 75mph to 160mph overnight jumps.

Yeah, two -PDO/Weak Nina seasons in a row with +PNA? That's what I'm thinking.. the PDO actually scores so high on long range predictability, and I found that when it didn't work one season, it worked the next season at 1.24x the average. Anyway, energy traders are hedging on a warmer Winter bet over the last few weeks. Natural Gas December contract dropping from $4.80 to $3.70 over the past few weeks.. despite -PDO rebounding a bit.. that's a bet on more +NAO conditions this Winter.

Again, with -ENSO (persistent +SOI), -PDO, -H5 over the Arctic during the Summer, I'm liking a blend of the last 5 Winters (20-21 to 24-25). We should at least get some cold shots, I don't think it will be a wall-to-wall warm Winter, like 97-98/01-02 or anything like that. 22-23 had some -EPO/-NAO patterns in Dec and March that didn't deliver, I'd take my chances with the same upper latitude pattern.

Philadelphia's previous 7-year low snowfall record was 13.2" The last 7 years has been 10.5".. they might be the epicenter. I know that I haven't had a storm over 5.5" since Nov 15, 2018.

I agree that 97L will likely stay out to sea, as CV storms passing NE of 60W/20N, stay out to sea historically 90% of the time. The ones that break that have a huge +H5 ridge over the top after it passes that point, and models don't currently have that.

I just think it's so interesting how Summer's with -SLP 60-90N since 2012 reversed in the Winter almost everytime. And it's not reversing as a -NAO over Greenland, it's 100% reversing, at 90N.

I think it's strongest 0 to +4 years.

Spring/Summer NAO roll forward, and +2 years after Solar Max also support a Winter +NAO at 0.2-3 correlation. I suspect we'll have the same deal as the last few years where the CPC NAO index will be positive, but the AO will be negative a lot of the time, with +500mb heights up near the Pole.

What I notice most is how backed up the mid-latitude jet is, as there are 3 regions with lower 500mb heights than the warmth to the north. When I mapped DC and Baltimore's top snowfalls/snowfall months/snowfall seasons, the same thing is true.. there are 3 areas of lower heights than even the -AO/-NAO +500mb heights to the north. This tells me that general -H5 is more important than having Polar blocking. I think the problem with my analogs is that the northern ridge is too far north: over 90N. 90N puts a mean trough at 45N, but not as much 39N. We need classic Greenland/Davis Strait blocking to do better. Unfortunately with Arctic ice melt, it's something that reverses 100% the following Winter, and that's centered 90N. I think this is why the new Euro seasonal has ridging/blocking centered at 90N.

^Phoenix broke their all-time August monthly high at 118F yesterday.

January on the Euro seasonal looks like -EPO/-AO

The 73-year average for PNA in July is a +0.2 temp correlation from ATL to NYC in +PNA vs -PNA, all data included.

Heatwave coming in France

Maybe not 50 years.. the 1980s were significantly cooler than now in the West coast warm season.. but some places broke the trend of recent years

Have fun in Africa!