GaWx

Every month of June-Oct have had a +PNA despite the very strong -PDO during the same period. Are there any implications?

Showing an area >+3.0 SSTS isn’t as absurd as it seems because it is only a small area. It goes only between 1.5N and 2S latitude at its widest point, which stretches only across ~15 degrees of longitude centered on 120W, the middle of Nino 3 and the far E end of Nino 3.4. Keep in mind that Nino 3 and 3.4 stretch from 5N to 5S, a 10 degree swath. So, the +3+ covers only ~1/3 of this at its widest, which stretches only across ~15 deg of longitude vs Nino 3’s 60 degrees of longitude or 1/4 of it. So, the +3+ area covers not much more than 10% of the entire Nino 3 and well <10% of Nino 3.4. Even the +2+ area covers <50% of Nino 3/3.4 meaning the +1 to +2 area covers 50%+ of Nino 3/3.4. So, Nino 3 likely averages only in the low +2’s at most on this map and Nino 3.4 is probably only ~+2 at most. For reference, TAO is already ~+2.5 in a portion of 120W and a little warmer than that just to the east.

Looking at the ONI chart, it barely missed a triple. Also, 2018-9 to 2019-20 barely missed a double. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

That’s actually likely since most peak in Oct or Nov. So, that wouldn’t change the equation.

There appear to be some questionable classifications in this per the IOD source I use: - 1987, 2002, and 2009 don’t belong in the -IOD column as Oct-Dec averaged positive for all three years - 1986 doesn’t belong in the +IOD column since Oct-Dec IOD averaged negative - 2018 (+), 2014 (+), 1976 (-), 1969 (-), and 1953 (-) were all left out - Note that the presented graphs were for NDJ rather than DJF - However, for the E US even after making these adjustments/additions/change from NDJ to DJF, the avg precip for +IOD still comes out AN/much wetter than that for -IOD while the avg temperature for +IOD still comes out significantly warmer than that for -IOD. You learn something new every day but this isn’t what I wanted to see for upcoming winter BN temp. chances. Thus, next El Niño I’ll be rooting for a -IOD. My monthly IOD source: https://psl.noaa.gov/gcos_wgsp/Timeseries/Data/dmi.had.long.data

The -SOI streak is still going. The current -SOI streak has just hit 60 days. Looking at model progs, it looks like it will reach at least 64 days. There’s a chance it will just make it to 66 days, which would tie it with 2015 for the 3rd longest since June 1991. This is a form of atmospheric coupling of El Niño: Longest -SOI streaks in days since June 1991: 100: Days 3-102 of 1998 72: Days 195-266 of 1997 66: Days 248-313 of 2015 60: Days 232-291 of 2023 and still going 55: Days 191-245 of 2015 46: Days 268-313 of 1997 46: Days 6-51 of 2010 43: Days 175-217 of 1994 https://data.longpaddock.qld.gov.au/SeasonalClimateOutlook/SouthernOscillationIndex/SOIDataFiles/DailySOI1887-1989Base.txt

Keeping in mind the high level of inaccuracy of the EPS weeklies, today’s version does have slightly higher H5 ht anomalies (slightly above normal) over Greenland and Iceland than to the south (near normal). Whereas the actual calculation of the NAO is based on SLP anomalies in Iceland and the Azores, H5 ht anomaly differences are often used to give a general idea due to a significant correlation. So, weeks 2-4 of Nov are leaning -NAO on this run after a neutralish week 1.

1. As mentioned before, there’s little correlation of both summer and Oct NAO to winter NAO. So, this means that having a strong -NAO this past summer and having one this month don’t, when looked at alone, increase the chance for a -NAO this winter. Based on progs, the Oct NAO has a very good shot to be within -1.6 to -2.1 (top 10 -NAO Oct since 1950) and may end up as the 5th lowest Oct NAO since 1950 (93 percentile). 1960, 1968, 1980, 1992, 1997, 2002, 2006, 2012, and 2021 had the 9 lowest Oct NAOs. How was the subsequent DJF NAO for these 9? 1960: +0.31 1968: -1.26 1980: +0.69 1992: +0.86 1997: -0.23 2002: -0.05 2006: +0.36 2012: +0.02 2021: +1.02 So, of these 9, only one (1968) had a -NAO winter to follow though it was strong. Three were neutral and five had a +NAO. 2. Whereas I found no correlation of Oct -NAO to winter -NAO, I do see what appears to be a pretty good correlation of a sub -0.75 Nov NAO to Dec -NAO. For the sub -0.75 Novembers, here were the Dec NAOs: 1950 -1.02 1952 -0.43 1955 +0.17 1963 -1.92 1965 +1.37 1968 -1.40 1969 -0.28 1973 +0.32 1983 +0.29 1995 -1.67 1997 -0.96 2000 -0.58 2010 -1.85 So, following a sub -0.75 Nov NAO, the following Decembers 9 of the 13 times had a -NAO, once had neutral, and three times had a +NAO. Out of the 13, five had a strong -NAO vs only one with a strong +NAO. Four out of the 5 El Niño cases had a -NAO Dec. So, what this is telling me is that if we can get a sub -0.75 next month, I’d actually feel good about the chance for a -NAO in Dec. So, I’ll soon start following the models for Nov NAO hints. Keep in mind though that only two of the nine lowest Oct NAOs were followed by a sub -0.75 Nov. due to no more than a small correlation.

Not only that, but I think we have a good shot at 1-2 months of DJF with an overall weak MJO (including many days inside the COD) hopefully with a lean toward the left side for the upcoming DJF. I say that because of the weak MJO so far this month (see below) along with the expectation based on model consensus that Oct 2023 as a whole will come in weak. Looking back at the 16 prior El Niños back to 1976-7, I found these 6 (38% of them) with weak MJO Octobers: 1977, 1982, 1987, 1997, 2002, and 2014. Here’s the subsequent MJO amp for DJF for these 6 weak Oct MJO cases: -D was weak 3 times, moderate twice, and strong once. -J was also weak 3 times, moderate twice, and strong once. -F was weak 3 times, moderate once, and strong twice. Now I’ll look at moderate Oct MJOs during El Niño: 1976, 1986, 1991, 1994, 2004, 2009, 2015, 2018. -D weak once (2004), moderate 5 times, strong twice -J also weak once (1977), moderate 5 times, strong twice -F also weak once (1977), moderate 5 times, strong twice So when comparing weak Oct MJO to moderate Oct MJO during El Nino, the moderate Oct tend to keep it mainly moderate in winter vs being weak more often than moderate during winter following a weak Oct MJO. So, it appears that during El Niño there’s some correlation of Oct MJO amplitude and the subsequent winter MJO amplitude based on weak vs moderate Oct stats. This image shows how weak the MJO has been this month so far:

Whether we’d get it or not, we’d be overdue for a -PNA or at least neutral PNA month in Nov. June-Sep were all +PNA months. Also, there’s a near certainty for Oct to do the same. There have been only 3 other years since 1950 with all of June-Oct having a +PNA (all +0.45+ in the current case). I don’t count 1960 and 1964 because they had lowest PNA months of +0.04/+0.15 within June-Oct, which I consider neutral.

The Oct 1-16, 2023, PNA after doubling the dailies to approximate what the monthly calculation would be is ~+2. However, it is about to fall sharply and is progged to be a -PNA for ~10/22-31. Though it will still easily end up a +PNA for Oct as a whole, this sharp fall will bring down this +2 significantly. How far is the question. For El Niño winters since 1950, here are the Oct PNA along with the nature of the subsequent winter’s temperatures in the SE US: 1953: +1.91 warm 2015: +1.78 warm 1979: +1.53 normal 1965: +1.14 cool 1977: +0.98 cold 1986: +0.92 cool 2014: +0.89 cool 1963: +0.69 cold 1976: +0.68 cold 1987: +0.53 cool 2009: +0.43 cold 1969: +0.35 cold 1957: +0.27 cold 1968: +0.26 cool 1951: +0.24 warm 2018: +0.21 warm 1958: +0.16 normal 1994: -0.23 mild 1997: -0.26 mild 2002: -0.65 cool 2006: -0.84 mild 1982: -0.93 normal 2004: -1.39 normal 1972: -1.50 normal 1991: -2.28 warm Although there’s likely some randomness involved, the fact that all 11 El Niño winters following an Oct with a PNA within the interval +0.26 to +1.14 were cool or cold and 11 of the 12 cool to cold Nino winters (out of a total of 25 Nino winters) followed an Oct with a PNA in that range seems pretty significant. It tells me that if the Oct 2023 PNA were to end up in that range that the chance for a BN SE 2023-4 winter would be higher than the ~45% for an El Niño winter in general and the ~33% chance for all SE winters.

Would you please post the 850 mb temps? What period is used for the climo base for the anomalies?

Do you have the 2 meter temperature maps?

Regarding the solar eclipse yesterday (10/14), this is from a San Antonio, TX, NWS discussion just afterward (1:52PM): “HOPEFULLY MANY OF YOU WERE ABLE TO SEE THE ECLIPSE NEAR THE PEAK OBSCURATION TIME. TEMPERATURES CURRENTLY RANGE FROM THE MIDDLE 60S TO LOWER 70S AND LOCATIONS CLOSER TO THE TOTAL ANNULARITY ACTUALLY DROPPED ABOUT 2-5 DEGREES WITH THE PEAK OBSCURATION.” One can get a good idea of the cooling influence of the eclipse by looking at Austin’s hourlies from yesterday since they had near full sunshine and no front coming through. The partial started at 10:24AM, peak obscuration (nearly 90%) was at 11:54AM, and the partial ended at 1:32PM. Note the steady rise 8-10AM, followed by a slowing of the warming at 11AM once ~1/2 hour into partial, a cooling of 3F 11AM-noon when going from some partial to the near 90% obscuration peak, the most rapid hourly warming noon-1PM when going from peak to losing most of the obscuration, and then steady warming through 4PM after the eclipse ended: 8AM: AUSTIN/BERGSTM PTCLDY 62 41 46 N14 9AM: AUSTIN/BERGSTM MOSUNNY 64 41 42 N16 10AM: AUSTIN/BERGSTM MOSUNNY 67 40 37 N20G29 11AM: AUSTIN/BERGSTM MOSUNNY 68 41 37 N14 Noon: AUSTIN/BERGSTM MOSUNNY 65 41 41 N12 1PM: AUSTIN/BERGSTM MOSUNNY 70 40 33 N16 2PM: AUSTIN/BERGSTM MOSUNNY 74 41 30 N15 3PM: AUSTIN/BERGSTM MOSUNNY 76 39 26 N14G22 4PM: AUSTIN/BERGSTM MOSUNNY 78 39 24 N13

On average, it does gradually though it will vary from year to year with ups and downs. The middle red line on the top image below is climo/normal of the mean zonal wind way up in the stratosphere (at 10 mb) at 60N. These winds correlate with the strength of the SPV. The latest EPS weeklies (from yesterday) are forecasting (mean is dark blue line) a stronger than normal SPV in late Oct, which is what @snowman19showed. However, this run then quickly weakens it to near to slightly stronger than normal for November: With an SSW, the mean winds drop as the SPV strongly warms. If those winds were to drop to negative, that means a reversal from the normal net E to net W winds and it is called a major SSW. The last occurred last Feb. Looking at the image below, the yellow line is the normal temp N of 60N at 10 mb. It hits a min ~Dec 1st. That’s when the chance for a SSW starts to increase. That chance rises to a peak in Jan/Feb before tapering off in Mar. Note how the light gray area, which shows the variance surrounding the mean, stays pretty narrow through Nov. That’s largely because SSW season hasn’t started. But then it widens a lot in Dec and hits a max mid Jan through early Mar, the heart of SSW season. Also, check out the red line, which shows 2022 through Feb of 2023. Note that after a very cold/strong SPV Nov/Dec, it hit all-time record cold of ~196K (-77C) 1/1/23! Even that didn’t prevent a minor SSW in late Jan/early Feb, a major SSW in mid Feb, and a secondary warming/wind reversal in late Feb, which all lead to a sharp drop in the NAO from Feb to Mar:

To clarify, although neither had an RNA and 94-95 had a +PNA, 53-54 actually had a net neutral PNA rather than +PNA.

Interesting! -Of the three -PDO/RNA El Niño winters since 1950, two were cool/1-3 BN in most of the SE: 1965-6 (had a cold Jan) and 1968-9 (all 3 of DJF cool). -ATL had its earliest measurable snow on record on 11/11/1968! -But despite a big snow late Feb of 1952, all 3 of DJF of 1951-52 were AN, especially J.

RNA = -PNA (reverse PNA)

-It is interesting due to its uniqueness though the PDO will probably rise significantly by winter. -These El Niño winters didn’t have a net RNA despite a net -PDO: 2018-9, 2006-7, 2004-5, 1994-5, 1972-3, and 1953-4 -These -PDO El Niño winters did have a RNA dominating: 1968-9, 1965-6, and 1951-2.

-True. How significant is it that the current sharp turnaround is occurring after a triple Niña vs after either a double or single Niña like 1972 and 1965? -The closest I can find to a strong Nino immediately following a triple Niña is the 1911-2 Nino, which peaked high end moderate (+1.4 ONI) after a triple Nina per this: https://www.webberweather.com/ensemble-oceanic-nino-index.html

Regarding turnaround within the same year, what about 1965 and 1972? They’re comparable at this point in the year. https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php

There are periods of both RNA and PNA during a typical winter. But the combo of it being El Niño instead of La Niña and how much cooler is the WPac N of Australia vs one year ago keeps me confident that a RNA won’t dominate. The last El Niño with a RNA dominating is way back in 1968-9. That means that there have been a whopping 18 El Niños in a row with either a dominant PNA (15 of the 18) or neutral (the other 3 of the 18): https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.pna.monthly.b5001.current.ascii.table

Thanks mainly to a major SSW of 2/16/23 along with a second 10 mb wind reversal/warming 2/27/23 and also considering the typical ~2 weeks it takes for strat weakening to work its way well down into the troposphere, the NAO went from the +1.25 of Jan and +0.92 of Feb to -1.11 of Mar and -0.63 of Apr. That resulted in the SE US during mid Mar the coldest period since January. The main reason there was an even longer than normal lag from SSW to colder E US along with a shorter than average duration of cold was a strong RNA late Feb-Mar, which partially countered the effects of the strong -NAO.

One very good way is to look at the SOI. You don’t get a 56+ day -SOI streak when not in El Niño: Longest -SOI streaks in days since June 1991: 100: Days 3-102 of 1998 72: Days 195-266 of 1997 66: Days 248-313 of 2015 56: Days 232-287 of 2023 and still going 55: Days 191-245 of 2015 46: Days 268-313 of 1997 46: Days 6-51 of 2010 43: Days 175-217 of 1994 https://data.longpaddock.qld.gov.au/SeasonalClimateOutlook/SouthernOscillationIndex/SOIDataFiles/DailySOI1887-1989Base.txt All 8 40+ day streaks since June 1991 have been during El Niño.

Wasn’t a lot of the W 1/2 of the US snowy? But much of the E US was the opposite. Maybe it came in as a wash for the lower 48 averaged out?? Or did the AN snow anomalies out west outweigh the E US BN anomalies? If it was a wash, the Euro over predicted.