PhiEaglesfan712

1998-99 had some moments. It was warm for most of the winter, but we got some good snows in the first half of January and in mid-March. Also, the snow on Dec 23-24, just a few days after we had 60-degree record warmth (and a few weeks earlier, it was in the 70s). That was the White Christmas that came out of nowhere! (We're well overdue for a White Christmas. I think the last one was 2002.)

Hypothetical summer 2025 strong la nina peak:

For the individual ones, it looks like 1975-76 is the closest to an east-based la nina. 1973-74: 1975-76: 1988-89: 1998-99: 1999-2000: 2007-08: The year with the closest to the east-based la nina is the one with the warmest RONI (peaked at only -1.14). All the other years at least got down to the -1.5 mark. I guess to get an east-based la nina, we may need a cold ONI and a warmer RONI, which of course, we're not getting this year.

Here is the composite of all the ONI strong la nina years:

What site did you use to get this? And how far does this go back? I want to see if I can create the other strong la nina years.

How do you do these composites? I want to be able to do some of my own.

While we're at it, can someone run the composite of the 8 ONI strong la ninas: 1955-56, 1973-74, 1975-76, 1988-89, 1998-99, 1999-2000, 2007-08, and 2010-11?

My thinking is that this upcoming winter will be similar to 1998-99 and 2007-08. Both were strong la ninas with cold subsurfaces. We'll likely have below average snowfall and above average temperatures, but there will be a moment of snow or two. Fall is most likely going to be warm and dry, while spring will be much closer to average temperaturewise.

I really like my analog years of 1998 and 2007. Those are the la nina years since 1949-50 that best fits a warm/dry temperature/precipitation profile. 1998 has all 3 months above average temperature and below average precipitation. 2007 works as well, except we had that mudstorm the last weekend of October that pushed the October precipation above average and November was below average. 1998: Sep (71.8F, +3F above average, 1.86 in); Oct (58.3F, +1.1F above average, 1.84 in); Nov (48.2 F, +1.1F above average, 1.18 in) 2007: Sep (72F, +3F above average, 0.58 in); Oct (64.5F, +7.3F above average, 4.66 in [2.83 from 10/23 to 10/27]); Nov (45.7F, -1.4F below average, 1.45 in) Uses 1971-2000 averages

Oh gosh, I hope not, lol. That would mean well above average temps and wet weather for October-January. At PHL, November 1976 was the coldest/driest on record, and January 1977 was the coldest on record. After the last 5 years, I really don't want a record warm/wet November and a record warm January. On the flip side, this would mean a cold spring (March-May), with a dry March and April, which probably means no meaningful snow, unless February (which would be a close to average month, but still wet) provides an opening for some snow. Either way, a very depressing fall/winter/spring combination. I'll rather have the anti-1986/87 analog. We may still get an above average temperature winter and a below average temperature spring, but at least the departure will be much closer to average. Plus, there's a better chance of snow potential sprinkled throughout the winter.

I definitely disagree with November being the warmest of the 3 months, at least here at PHL. I think September and October are going to be well above average. In fact, if there is a below average month in the fall, I think it's November.

I don't like the 22-23 analog at all. That was a 3rd year nina that pretty much peaked in the summer and dissipated during the winter. Plus, that one had a warm subsurface. This is pretty much an opposite set-up to what we have this year. Now, if we have the scenario where a strong la nina peaks next summer, I'd use it as an analog for 2025-26. But definitely not a good analog for this year.

I've been saying that the anti-86/87 scenario could occur, and the la nina could peak as a strong one in summer 2025. (Just don't expect it do dissipate really quickly in the winter of 2025-26, and transition into a super el nino in 2026-27.) I'd assume a summer peaking strong la nina would be very hot and dry in the East, and most of the United States, for that matter. The closest thing to strong la nina conditions in the summer was 1988 (heading into the historical la nina), following the dissipation of the el nino that began in 1986.

If I remember correctly, the RONI and ONI were almost in line in 2009-10. The 86-87 one was weird. The RONI had a double peak, while the ONI peaked in the summer. JJA 1986 RONI: 0.25 ONI: 0.3 JAS 1986 RONI: 0.55 ONI: 0.6 ASO 1986 RONI: 0.87 ONI: 0.9 SON 1986 RONI: 1.12 ONI: 1.1 OND 1986 RONI: 1.35 ONI: 1.2 NDJ 1986 RONI: 1.49 ONI: 1.2 DJF 1987 RONI: 1.54 ONI: 1.2 - First RONI (winter) peak JFM 1987 RONI: 1.43 ONI: 1.2 FMA 1987 RONI: 1.17 ONI: 1.1 MAM 1987 RONI: 0.87 ONI: 1.0 AMJ 1987 RONI: 0.77 ONI: 1.1 MJJ 1987 RONI: 0.94 ONI: 1.3 JJA 1987 RONI: 1.23 ONI: 1.6 JAS 1987 RONI: 1.46 ONI: 1.7 - Second RONI (summer) peak ASO 1987 RONI: 1.43 ONI: 1.8 - ONI peak SON 1987 RONI: 1.24 ONI: 1.7 OND 1987 RONI: 1.02 ONI: 1.4 NDJ 1987 RONI: 0.93 ONI: 1.1 DJF 1988 RONI: 0.65 ONI: 0.7 JFM 1988 RONI: 0.30 ONI: 0.3 So, the RONI began and ended the el nino at roughly the same. In between, the RONI was ahead by as much as .34 over the ONI in the winter. This would flip flop during the year, as the ONI ended up ahead as much as .46 over the RONI by the fall. Of course, when this el nino dissipated, it transitioned into a strong la nina in 1988-89 (just as the 2009-10 strong el nino transitioned into the 2010-11 strong la nina).

Knowing what I know now, I probably would have used 1957-58 and 2009-10 as the best analogs for 2023-24. 1957-58 had the best ENSO match to 2023-24 (I mean the 5 year lead up matches perfectly: 1952-54 disjointed el nino = 2018-20 disjointed el nino and 1954-57 triple la nina = 2020-23 triple la nina). 2009-10 had the best RONI match to 2023-24. Both 1957-58 and 2009-10 were very snowy winters in the PHL area, so I probably would have predicted 2023-24 to be a very snowy winter, which didn't pan out.

This would almost be a perfect ENSO/RONI/subsurface match to 1998-99.

1998 is a very good analog:

That cold pool in the subsurface is getting stronger. A strong la nina is definitely coming at some point in the next 12 months.

I still think the anti-1986 scenario is in play, where we get a strong la nina, but it peaks in the summer of 2025 rather than in the winter. If this happens, then how fast the la nina dissipates in 2026 will be key on whether we have an el nino in 2026-27, and how strong it will be. One thing to keep in mind is that la ninas are much harder to dissipate than el ninos. Perhaps the biggest reason why we were able to get a historic la nina in 1988-89 is the fact that the el nino that peaked in the summer of 1987 quickly dissipated starting in early 1988.

2011 is another year that had a rainy August-September. Oddly enough, both 1999 and 2011 led into 2nd year la ninas.

I'm going to assume that one of those 1988's is supposed to be a 1998. If that's the case, then all of those +PNA Julys produced a strong la nina, with the exception of 2022 (which was a 3rd straight moderate la nina year). Of course, 2022 was the only one that didn't transition from an el nino the previous year. So, we'd be breaking some trends if we don't get a strong la nina out of this.

MJJ ONI (NOAA): +0.2C MJJ RONI: -0.38C

Rainy week ahead:

At PHL, 1998-99 stayed warm throughout all of August-February, and didn't have a below average temperature month until March. April and May were near normal. 2007-08 had a very warm August-October, then went below average in November. December was near normal, and we didn't have another below average month until May. My prediction: August-October: Well above average November-December: Near average January-February: Above average March-May: Near average

I hate that the graph cuts off at 2010, so we don't get to see the entire picture of that first strong el nino in full. I wish they had started in 2009. But the fact that the 2019-20 (a year with barely an el nino) had more red than the start of 2010 (at the peak of a strong el nino) should tell you all you need to know about global warming in the 2010s decade.