raindancewx

Still following the progression of the four most recent El Ninos, but at much more extreme severity. The +15F stuff centered over Kansas should wash out a bit by the end of the month, same for the -5 to -10 centered on Oregon. We're seeing widespread heavy rains this month in New Mexico after very little rain in June-Aug. Will be curious to see how the month finishes locally. But 2015/2018/2023 had fairly wet Septembers as well locally.

Again, we are tracking the last four El Ninos rather well as a blend.

Roughly 20F off so far for parts of Iowa. No big deal. Only 10-15F or so by CA/OR so far. La Nina Modoki / El Nino traditional tend to favor the West Cold Fall-Spring (E Pac relatively warm v. W Pac at the equator in each case).

Summer heat over the West looks like it has been destroyed, as Sept has been cold so far over some of the warmest areas, with more cooler than average temps coming for a while. Especially with significant rains likely from the dying East Pacific hurricane running north. Our local pattern of "every day is 90-105" has finally broken in Sept, which is nice. More rain forecast will help if it verifies.

August and Summer (Jun-Aug) were warm for basically the entire lower 48 this year. I fudged the scale on this to make it closer, but the pattern resembled a 1994, 2003, 2012, 2018 blend. In the Summer, 2003/2012 were both El Ninos in terms of SSTs (close to 28C). June-August was my hottest Summer on record: average temp of 81F here v. 80.4F (2011) previously. El Ninos that show up as both near record hot and near record dry are 1953, 1958, 2003, 2023. These are highs for the following Oct-May. Bold is colder v. 1991-2020. 1953-1954 72.6 58.4 42.9 50.3 61.4 58.9 76.8 81.0 62.8 1958-1959 68.6 58.6 54.6 45.4 51.2 59.6 70.4 78.8 60.9 2003-2004 74.3 56.3 47.8 48.4 48.2 65.3 65.7 81.8 61.0 2023-2024 74.8 57.9 49.7 48.5 56.1 60.4 70.8 81.2 62.4 No strong signal for any time-frame being cold, but March is closest followed by February. You've got no real cold signal at all in these years in the Fall, Oct 1958 is -2F, Nov 2003 is -1F, but those are washed out by the others. Dec 1953 is about -5F, but Dec 1958 is +7F. Jan 1959 is -3F, others warm. Its really Feb/Mar with the best shot. Feb averages out to about 1991-2020 mean high, and March averages out 2F below it. Even for March, you have a warm counter-example. Oct-May Oct Nov Dec Jan Feb Mar Apr May Oct-May 1953-1954 0.46 0.91 0.29 0.20 0.07 0.24 0.00 0.51 2.68 1958-1959 1.72 0.37 1.35 0.17 0.04 0.42 0.43 0.80 5.30 2003-2004 1.58 0.49 0.11 0.10 1.17 0.67 3.00 0.00 7.12 2023-2024 0.00 1.00 1.01 0.33 0.41 0.27 0.33 0.06 3.41 0.94 0.69 0.69 0.20 0.42 0.40 0.94 0.34 Precip has mixed signals too, but each month from Oct-Dec has 2/4 years with 2x average precipitation or more, so that'd be my guess for the wetter period. January looks much drier than average with no above average months, and Mar-May is very erratic but finishes near average as a blend, largely on 2003-04. Best guess is 2-3 wet months from Oct-May. Snow is much more interesting - about 12.3" total, which is what I keep getting when looking at similar patterns. Nov, Dec, Jan, Feb are all 3/4 cases of measurable snow, March is 2/4. My research has previously shown that hot/dry Summers locally favor "out of season" heavy snow. You can see Oct-Nov/Mar-May snow averages 4.0 inches in these years, which is high for those months locally. November has the strongest signal relative to average for a snow event (more likely than average (75% v. 50%) and higher totals than average (2.7" v. 1.0"). December has one of the top ten snow months locally as well, Dec 1958. 1953-1954 0.0 7.5 3.7 2.9 0.0 0.0 0.0 0.0 14.1 1958-1959 0.0 2.2 14.2 1.7 0.6 4.8 0.0 0.0 23.5 2003-2004 0.0 0.0 2.0 0.0 2.7 0.7 0.0 0.0 5.4 2023-2024 0.0 1.0 0.0 2.4 2.7 0.0 0.0 0.0 6.1 Blended: 0.0 2.7 5.0 1.8 1.5 1.4 0.0 0.0

Canadian update shows PDO trending positive through Feb-Mar before reversing again. It shifted the center of the El Nino east. Still has a central event, which is why it is cold for the East. But it is shifting the warm plume/enhanced equator moisture east with each run now.

August SOI is approximately in the top ten most negative for the last 100 years. Finished at -14. These are the -10 SOI or lower Augusts, rolled forward to December. The -12 to -16 SOI Augusts, 1953, 1987, 1993, 1994, 2002, 2006 produce the same result. Aug SOI is pretty strong as an indicator for February too. Very strong correlations for a cold SE/warm NW as you'd expect with any ENSO correlation.

August SOI is traditionally a much stronger signal for a warm Northern US December than Nino 3/3.4/4. Month looks like it will finish among the lowest ever SOI readings for August. Vast area of Southern Canada/Northern US favored warm at a strong correlation already. For whatever reason, the August SOI is more predictive for Dec temps than the Sept SOI as well.

Southern South America has been seeing a cold winter (their winter is our Summer). That's fairly normal for an El Nino "expected effect". The Southern Hemisphere +PDO is sort of there, warm ring around a cold tongue. Areas expected to be warm in El Nino have been running +10F or more in winter - good preview for our winter in the northern US I'd expect.

The recent El Nino Summers (2015, 2018, 2019, 2023) as a blend are pretty close to 2026 for Jun-Aug - not quite by magnitude but in terms of pattern. Close match for Sept on the CFS too. Honestly, it's probably a decent match overall. 2015/2023 - very strong El Ninos with high solar, neutral/negative PDO values in all four years. Warm Atlantic. 2015/2018 both followed very warm/dry Western winters like 2026 will. Decent QBO match too.

The Canadian outlook for August verified way too cold for the US. Far too wet too. Worth keeping in mind for what it shows over the next few months. Fall months are often the hardest to predict anyway, particularly October, so not expecting much accuracy from these outlooks for a while. Colorado is +5F in areas expected to be -1F to -2F v. long-term averages as an example.

I've been disappointed with the E Pacific hurricane season so far. Was hoping we'd have several land falling systems on Western Mexico to help with rain out here. Nothing. CFS is insistent every month from Sept-Mar will be wet locally. We could use that. CFS also has the entire US, except for New England, cold at least one month from Jan-Mar, so that's encouraging to see. For comparison, 2023 had 11 named systems in the Atlantic by 8/31. We're at...four. By the end of August, 2015/2019 had five, 2018 had six, and 2014 had three. 1982/1997 were relatively quiet too. 2004/2018/2023 are the more recent active hurricane seasons in El Ninos. Nice to see we're not getting a big hurricane season with this. Wyoming is favored wet in El Nino Augusts. Other than that, precipitation is still not behaving with an El Nino look. No AO/NAO/WPO/EPO/PNA signature to it either.

Going to be very interesting to see if we get 'normal' El Nino conditions here. So far the Summer here has been about as hot as ever recorded, with near record low precipitation as well. 2023 was even drier in the Summer, but we're running hotter. Summer has been very close to 1953, 1958, 2023 as a blend, all the sort of drought plagued, -PDO, El Nino, very +AMO shit years locally. It's actually been very interesting - for the past month little batches of rain showers have formed late evening almost every night. But they are widely scattered and have only brought drizzle to the city most nights. A lot of the terrible monsoon years don't even have the showers form. But they typically perform best for rainfall late afternoon to about 8 pm. We've seen showers develop in the 8 pm to 2 am time frame and then sizzle out, which is unusual here for formation time. The Atlantic has really warmed up quite a bit relative to averages over the past 2-3 weeks. I think we will actually see a brief period of decent hurricane season activity in September. My hottest average temperature El Nino Summers are these winters: 1994, 2023, (2003 borderline El Nino), 1958, 2018, 1953, 2002. We tend to get fluky out-of-season heavy snow events following very hot and very dry Summers here. 1994-95 snowed a lot in April, 1953-54 in November, 2002-03 in March, 1958-59 in March, 2023-24 in November. Several of these also see good snow in the main winter too. My guess is the MJO will set up to favor bigger storms nationally in something like an Oct 15-->Nov 30-->Jan 15-->Mar 1-->Apr 15 fashion for major events given the local Summer data supports unusual concentration of heavy snow events in Nov/Mar/Apr so far, more than the winter.

PDO has definitely weakened toward neutral in recent days. Net trend will be more positive. It's just whether that continues into actual positive territory and sustains. The North Atlantic on the other hand has also warmed up quite a bit.

July was similar nationally to 2002, 2003, 2006 more than the recent El Ninos, in terms of US temp profile. Recent events (2009-) were either much colder or had different spatial distributions for warm/cool areas. July is close enough to winter that you can probably infer meaningfully what will happen from the tele-connection set. This is July 2026: -EPO, -WPO, +PNA, -NAO, +AO. Of those, EPO was extremely negative. -EPO July, El Nino: 1957, 1963, 1969, 1976, 1979, 1986, 1991, 1997, 2002, 2003, 2006, 2018 -WPO July, El Nino: 1953, 1957, 1969, 1972, 1986, 1991, 2002, 2006, 2014, 2018, 2019 +PNA July, El Nino: 1953, 1958, 1969, 1979, 1982, 1991, 1997, 2002, 2006, 2009, 2014, 2015, 2019, 2023 -NAO July, El Nino: 1957, 1958, 1963, 1968, 1976, 1977, 1991, 2009, 2015, 2019, 2023 +AO July, El Nino: 1951, 1953, 1969, 1979, 1982, 1994, 2002, 2006, 2018 On the five signs, you only have a handful of El Ninos that are 3-4-5 match candidates. Those are bold above. 3 match group: 1953, 1957, 1979, 2018, 2019 4 match group: 1969, 1991, 2002, 2006 If you roll that nine year blend forward to winter - certainly somewhat more muted and different spatially then what I expect. The -EPO July is actually a fairly big warm signal for the following December in the Great Basin, weaker for the rest of the West to the NM/AZ border, and a weak cold signal for the SE US south of DC. That's like a +30% snowfall winter composite for me. All of those winters have fairly notorious off-season flukish snow events, which is a major feature of El Nino. You can get heavy snow in Oct-Nov and/or Mar-Apr in additional to decent snow in winter.