Stormchaserchuck1

Trend has been really strong for the last 7 years that we have a Feb-March -PNA. At the flip of the month, it's doing it again this year. Late blooming La Nina also enhances the SE ridge probability late Winter, and +QBO has been helping 10mb stay very cold this Winter, disallowing Stratosphere warmings. For the last few years, our cold late Winter has come from Stratosphere warmings, but that is looking less likely to occur this year. I would say we veer toward a -PNA/SE ridge pattern through March, but the 2-month period of cold late November through mid January was really uniform and solid.. those type of patterns usually come back at some point later in the Winter. So a bit of a conflicting forces.. I'd probably go with slightly above average late Feb through March, +EPO being less likely and a Winter trend of -EPO/-WPO probably means that I would wait until April to plant.

Yeah we really flipped from +AAM earlier in the Winter to -AAM now. This is a completely different pattern happening: 12z GFS ensembles go wild with RNA in the long range. It's a brutal pattern for snow in the Northeast with +NAO and -PNA, maybe until mid-February..

I just think it's a really strong signal on the mean for being so far out. I think the mean is approaching +300dm south of the Aleutian islands. It's been going back and forth a lot this Winter, I've seen -PNA patterns dissolve and move into -EPO domain in future time this Winter. If the EPS isn't aligned that's a little cause for less confidence.

Pattern's probably underestimated right now for how warm it can get here.

Well it would take a massive shift in the GEFS H5 for snow to occur, 1/50 type stuff. Maybe it's somewhere between the 2 models.

EPS has probably been better in that range this Winter. It's the first run where the GFS ensembles have such a strong signal, so I'd like to see it sustain for a few more runs, but verbatim that's at least 60s, maybe 70s, because it's happening with a +NAO.

12z GEFS really went wild with the -PNA/SE ridge pattern in the medium-long range. 5700dm heights for Feb 10th on the mean, so if the Euro is showing snow it's an outlier.

I'm still thinking the NAO/AO err's positive this cold season. QBO/Weak Nina may continue to be with cold 10mb (been very cold at 10mb this Winter so far), and my Summer N. Atlantic SST index was +NAO for DJFM.

+NAO is kind of hard to break right now with strong +QBO/Weak Nina. It's holding strong through the next 15 days, and maybe beyond. Cold 10mb has been a real strong factor this Winter. Recently in the last few years, our late Winter -NAO's have happened with Stratospheric warmings.. it will be interesting to see if we can produce the same result without that strong variable this year, if this does continue to happen (cold 10mb vortex 0.5 correlated to +QBO/Nina).

@40/70 Benchmark Winter NAO should be near 0.0 after the 15-day period here It might even average out positive for DJF. (I know you were saying NAO forecast was a bust, that's not really true because of this 2nd half of Winter +NAO surge).

For whatever reason, the Pacific -PNA pattern has been a ridiculous consistency since 2018 in the late Winter (Feb-March). I'm curious to see if that pattern holds or breaks this year... all else neutral, I would say -PNA would prevail. A different pattern would be impressive, it would mean something else is occurring globally right now.

I always think La Nina being a cold weather event isn't as bad as it's made out to be.. later in the Winter -PNA does correlate with -NAO a bit more, too. I don't think it's enough data though where you have neutral trumping. Do fading El Nino's to Neutral do better late Winter snow vs sustained El Nino's?

The pattern this Winter in the Pacific was not bad for a west-based La Nina.. be happy that it was weak.. if we broke <-1.0c or lower for the large region it probably would have been different.

Finally feels warm out today for the first day in a while.. the start of a long lasting pattern change though

I can't believe the Chiefs are favored over the Eagles in the SB.. Philly has a much better team: Hurts, Barkley, AJ Brown, Devonte Smith, 3 pro bowlers on the O-line, and NFL #1 ranked defense! They haven't lost a game with Hurts as QB since September. 2 years ago Hurts went on a 25-1 streak covering 2 seasons, so they do get streaky hot. Eagles are a formidable team.

The long term decadal pattern going into Feb-March

La Nina was a late bloomer this year. ENSO subsurface cold didn't get going until late December. Now it's impacting the Pacific pattern in February, and probably March.. It was neutral in Oct-Nov.

February 2018-2024 had a mean 500mb height over the PNA region of +150dm! I went back to the beginning of satellite data in 1948, and found out that the 2nd strongest anomaly covering a 7-year consecutive period was +95dm -NAO 1964-1969 (only 6 consecutive years though). That means that going into this year, we were on a streak of breaking the previous record by 155%! Now models are showing a strong -PNA for this February! That's going to make it year 8 in a row. The streak does also extend into March, as 2018-2024 had a -PNA of +85dm for that 7-year consecutive period.

When the ridge goes up into Alaska, the surface is much colder than 500mb across the eastern 2/3 of the CONUS

I'm kind of getting tired of saying the same thing as the last few years -- Neg PNA and +NAO builds in, shutout coming for at least 2-3 weeks. I was waiting for a good setup for snow and it just didn't come after that first one in the new cold pattern. Originally, the 2nd storm looked like that could phase with the PV, but then that trended much more disconnected and we only got 1". More of the same as the last 7 Winter's right now -- strong RNA for February. Our 7-year average for Feb/March broke #2 going back to 1948 for strongest 500mb anomaly by +170%, and it's interesting that that looks to continue for year 8. Definitely something is causing these 2nd half of Winter -PNA periods. The 2-month period from late Nov to mid Jan was fun though.. it snowed here 15 times (flurries or more).

We have seen a La Nina STJ

Really unfavorable period for snow coming up along the East Coast. The NAO/AO are going strongly positive, and a -PNA is building in and it looks like holding strong. This -PNA Is associated with ENSO subsurface negative anomalies, that really picked back up about 3 weeks ago.. since then we have gradually transitioned from +PNA to -EPO (neutral ridging over PNA region), to now -PNA. It's hitting the most unfavorable part of the cycle here in about 2 weeks.. I wouldn't expect any snow south of Boston until the pattern weakens, that could mean a few weeks. It was a really nice 2-month pattern though from late Nov until now.. but big pattern change underway.

ENSO is just a mover of the Pacific pattern, not something that trumps it. Wavelengths at our latitude make the difference, so you would be more accurate measuring +PNA or -PNA events for snowstorms. It does also connect with the STJ though, but you still need cold, and it's just not coming or "reloading" from now to the time of the storm.

Yeah it's pretty close - I don't like that we have high heights out ahead of the trough with this storm. Make a composite of 15 GOA or -PNA ridges, and 13 or 14 times it evolves too warm for us to have snow.. it is close to the coldest time of the year, but we need a better pattern imo.

I've said this before though - It's ok that the South, like Texas, Oklahoma etc get a snowstorm out of this. The pattern changes quickly from the -48hrs to the time of the storm. We have no high pressure to the north.. By the time the coastal makes it off of Ocean City, we will be above freezing. That High pressure organizing in the Gulf of Alaska is the reason.