Weak La Nina Winter

[AfewUniversesBelowNormal]

last 7 days not included

[raindancewx]

In some ways, unlike El Nino, Nino 4 is the best measure of La Nina conditions, and its warming, both surface and subsurface. Nino 3.4 is warming as well. The trades have relaxed / reversed to some extent, and the SOI still looks slightly to very negative for the next ten days on the GFS to keep that going.

It's going to take a while for Nino 1.2 and Nino 3 to warm up. Those areas are still cold, around -1C, with lots of subsurface cold water. Nino 4 is 160E to 150W, and is going to get attacked from below by the warm waters that are on the maps above. SOI only matters in the sense that those waters are more likely to get pushed east into Nino 3.4 if Darwin has high pressure and Tahiti has low pressure. The Nina isn't really in any immediate trouble, to me it looks fine until sometime in mid-March to mid-April. Tropical Tidbits shows a rise from -0.8C for a month to -0.3C recently in Nino 4, and -1.0C to -0.6C in Nino 3.4.

SOI peaks as an indicator for the West this time of year, with correlations approaching 0.7 in some areas for SOI in February and Feb/Mar precipitation, so the trades mean something. The odds of a 20-point SOI drop month/month are up to 25%, which would put the crash in the top ~1% of crashes since 1931. Similar crash happened by magnitude/timing to 1997, in an East-based cold ENSO year.

[AfewUniversesBelowNormal]

Subsurface below Nino 4 is warm in La Nina. SOI is definitely a sub-tropical jet index, but it doesn't correlate much with changes in ENSO. 1972, 1983, 1997, 2015 Strong El Nino's didn't have negative SOI until event was already developing. I did research once that correlated patterns with various ENSO indicators and a custom subsurface index had the highest correlation with Northern Hemisphere 500mb pattern, 0 lag, 3 lag etc, precip, all ENSO marks. This La Nina is at its strongest point now. 

[raindancewx]

My point was that the sloshing of the Nina induced warmth/cold in various zones does seem to follow SOI changes, don't forget, there was a huge SOI spike Jan 16-29. Nino 4 warming with a negative SOI sending the waters east isn't a great signal for the La Nina going forward given how warm Nino 4 will be relative to the other zones. The SOI was +15 to +30 for two weeks in late January, and that really helped move the Nino 1.2 cold west. The -10 to -30 readings lately should help move the Nino 4 warmth east...but there is a bit of a lag. Seems to be 5-20 days. The images Wolfpackmet posted are consistent with the SOI sloshing idea.

[AfewUniversesBelowNormal]

I disagree

On plus side, last years Spring El Nino was already well underway by now so I think we can rule that out. MAM may be negative or around zero based on what's happening now. March is very likely -PNA

[raindancewx]

I like Nino 3 < Nino 1.2 < Nino 3.4 < Nino 4 in terms of what is coldest and what is warmest in an anomaly sense for Spring. February SSTs in Nino 3.4, 3, 1.2, kind of look like a blend of 1967/1975/1981 to me, with maybe some 2006 or 1985 thrown in for good measure.

Nino 1.2 is the real mystery, coldest reading in January since 1981, no warm waters to the south, west (east is land), or subsurface to warm it up. No idea what the time line is for that. Euro initialization just came out and seems to support my idea?

[raindancewx]

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA

 03JAN2018     22.9-0.8     24.0-1.4     25.8-0.8     28.3-0.1
 10JAN2018     23.3-0.9     24.3-1.3     25.6-0.9     28.2-0.1
 17JAN2018     23.9-0.6     24.7-0.9     26.0-0.6     27.9-0.3
 24JAN2018     24.0-0.9     24.7-1.1     25.9-0.7     27.8-0.4
 31JAN2018     24.4-0.9     24.8-1.2     25.8-0.9     27.7-0.5
 07FEB2018     24.9-0.7     24.9-1.3     25.8-0.9     27.8-0.3

Some warming this week on the edges of the La Nina as Tropical Tidbits has been showing. Increasingly East-Central rather than East-based. Also, this is the first time on the weeklies in over a year (edit: since 3/29/17) that Nino 1.2 hasn't been colder by temps than the other regions. That's a big change. Nino 1.2 was running 5-6C below Nino 3.4 in October/November. Now its only 0.9C colder. It's tied with Nino 3 now.

The warmth below the surface does seem to be intensifying and slowly spreading East again, but its not into Nino 3.4 yet except for the rogue piece of the wave that ran up to 100W by the surface.

[AfewUniversesBelowNormal]

La Nina is higher thermocline west of 160-180, lower thermocline east of 180. or that's the common occurance

This can't really leave La Nina signature until April at the earliest unless some really anomalous stuff happens. A thread on easternuswx.com was well researched, maybe you can find it somehow "Subsurface ENSO index", Stormchaserchuck. It proved that in the face of 70 years of data, the surface isn't even worth paying attention to because of how high subsurface thermocline difference east vs west correlated to pattern. It was plotted with monthly index numbers, some years like 92-93 and 93-94 were El Nino, 95-96 wasn't La Nina, etc. 02-03 was weak El Nino. There was a difference in Pacific PNA of 0.70 subsurface vs 0.55 surface even though surface and subsurface correlated 0.80. And of course Nino 3.4 correlated more than Nino 3, MEI, TNI etc. 0.70, 0.55, 0.50, 0.47 etc subsurface being first. I'm only going off memory

I would say this higher correlation has been true this Winter. For example, largest -PNA Of season is happening now as subsurface is becoming strongest La Nina signature vs surface warming. and when I say largest signature I mean west vs east +0.60/-0.40 (the boxes werent touching each other either)

[raindancewx]

The thermocline numbers from NOAA last Spring had the "positive" slope they talk about as La Nina or cold Neutral conditions, which is probably an OK proxy for the index you are speaking of. You can see for yourself - https://web.archive.org/web/20170329181127/http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf

To be honest, even from the list you have 2002-03, not super different from observed Dec-Jan highs, or even fairly expansive dryness nationally, like this year even with opposite thermocline right? Weakly Nino in a thermocline sense? Positive PNA in December & January despite the differences in the thermocline?

I find that matching the relative nature of the three Modoki boxes in Neutrals, and weak La Ninas and weak El Ninos is a pretty good predictor for US conditions, at least temperatures. When Box B (East Pac) is sufficiently colder than Box A (Central) you get an east/west split for warm/cold in some manner. The left map is when Box C is cold, and Box B is colder than Box A, the right map is when Box B is colder than Box A, but Box C is warm. It looks pretty close to how this year will end up don't you think? February will burn off a lot of the cold in the East, and the West will be hot. The anomalies are a composite, and will never be perfect for a given year from an average but the idea of a hot West, and somewhat cooler East is dead on just from the Modoki structure.

 

[AfewUniversesBelowNormal]

I want to clarify, by strongest of season I mean Trend versus seasonal trend in standard deviation. I've also found that things like MJO waves do not effect the subsurface as the subsurface seems to be an independent variable that moves various things in time +10days, 0 days, 10days as the same. Once there was a Nino 4 vs 1.2 index and Nino 3.4 vs Nino 1.2 weighted for differences in SD etc and it actually gave no conclusive result as an advantage pattern indicator. Also, subsurface ENSO index as a general signal correlates with North Pacific High and Trend relates to West vs East, Ninatrend in La Nina= more Aleutian High, weakening trend in La Nina or 0trend = Gulf of Alaska High. 

[AfewUniversesBelowNormal]

Also when the La Nina become self sustaining, based in Nino 3.4 and 4 (where the east-based events use land torque). This is when it cycles with North Pacific pattern

[raindancewx]

SOI is still -18.15 for Feb 1-14, down from +8.9 in January. Pretty good rains and snows today for Arizona, they may not finish too far below normal precipitation out there for winter.

JAMSTEC has a warmer Nino 1.2, with near-Nina conditions persisting in Spring (its probably similar to the Euro which has the Nina lasting to April). Its trended to a positive look PDO for Spring, and a much colder Atlantic also.

Drier Spring now forecast too relative to January, although the trend is to less dry on the West Coast, which is what I had in my Spring Outlook. (https://t.co/85VPbQq1bD)

There is no currently no El Nino forecast on the Jamstec for 2018 - but it does have kind of a true Neutral, where Nino 3.4 is +0.2C or so in Fall, but Nino 1.2 is -0.2C.

[AfewUniversesBelowNormal]

Subsurface had been weak all Winter, negative neutral to borderline Weak Nina, now it's on the brink of Moderate La Nina. Check out these 5 day SST changes. 

https://imgur.com/a/VuD37

Surface rapid warming, subsurface rapid cooling, SOI is negative. North Pacific is as La Nina as it's been

 

[raindancewx]

This is Tuscon. This is why I was excited about the SOI drop. These are huge numbers for the Southwest in winter. Looks like ~1.3" since yesterday? Did pretty well here, but Tuscon gets 2.7" or so in winter, so 1.3" is huge for 36 hours. 

 

 

[raindancewx]

Since 1950, there are only two years with a -SOI in February (near-certain now) and within 0.4C of Nino 1.2 reading (23.32C) in January 2018:

January-February 1959

January-February 1981

The blend of those years look not only like Dec-Jan temperature anomalies, but also February. So, suspect its going to be a decent match going forward into March, but its kind of a crazy look for March (I think its warmer in the SE then it shows, colder West Coast)

 

[Stebo]

Early March on all the long term models look nothing like 1959 or 1981, if anything complete opposite

[Stebo]

The subsurface has actually cooled some in the east over the last couple of weeks, surface has followed suit except the far east.

[raindancewx]

The analog matches could break, but the models have been bad for the last few months. The Euro monthly (Feb 1 run) for February had a much warmer US, it missed the extreme precipitation in the SE/SW, and the extreme cold in the middle third of the USA. The best forecast I've seen for February was from Larry Cosgrove, he had a hot SW, a hot SE/NE, hot NW, and the cold in that middle US triangle with the point by Brownsville.

The Euro apparently missed the SOI awakening the subtropical jet too.

The issue for March is the -Nino 1.2 / -Nino 3.4 anomalies and -SOI anomalies in February are correlated to opposite effects. The SOI is a better precipitation indicator nationally than Nino 1.2 for February temperatures, and even a bit better than Nino 3.4.

I should also point out, Nino 1.2 & Nino 3.4 produce opposite effects in March for temperatures in the SW. A warm Nino 1.2 in February is a weak warm signal in the SW. A cold Nino 3.4 in February is a strong warm signal in the SW. We had a warm Nino 1.2, and a cold 3.4 last year, and roasted. This year, Nino 1.2 is colder though, and the SOI in February is also a decent March indicator, and much lower.

 

[AfewUniversesBelowNormal]

The United States is pretty localized imo. If you map 0-360, 0-90, or (-360-360,-90-90) ENSO is exactly in the middle, Nino 3.4 or 4

[csnavywx]

The strongest MJO event since the 2015 just occurred. In combination with equatorial rossby waves, a long-lasting westerly wind burst has been ongoing for a few weeks now. That's resulted in a big downwelling equatorial kelvin wave. Stebo's TAO chart shows it well. That will be the death knell for this Nina once it reaches the surface, barring a big trade surge to slow it down.

The WWB will subside in a few days as the MJO enters its inactive phase over the WPac, but there are some hints it may come back in a few weeks for another pass. We'll have to see.

[raindancewx]

For 2/18 to 2/27, if the GFS is remotely right, the SOI is going to reverse substantially. But it looks gradual at first, probably a couple slightly negative readings through 2/19 or 2/20, then a couple near 0, then positive. I think 2/18 to 2/28 may come in around +2 or +3 overall. That's against the -289.01 (-17) observed for Feb 1-17 though. Going to be a close call on a 20-point drop, from the +8.93 in January. I'd like to see one more big negative reading tonight, at that point I think its a coin-flip on a 20-point drop, something like 35x more likely than historical long-term frequency of a 20 point drop. 

Getting back to even a 0 SOI for February would require a bounce to +26.3 readings each day for Feb 18-28, and that's not happening, as the highest Feb SOI reading is like +22.6.

I looked up the 1887-1989 base sea-level pressures BOM uses, and its 1011.351mb for Tahiti, and 1006.597mb for Darwin. Tahiti has been much lower, like 4mb, than that month to date, but Darwin hasn't been much higher.

If anyone wants to estimate readings for the rest of the month its ((Treading-1011.35)-(Dreading-1006.597))*(4.77) roughly. The x4.77 seems to capture the standard deviation readings they use for each site as an OK generalization from my testing.

[raindancewx]

                Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA

 03JAN2018     22.9-0.8     24.0-1.4     25.8-0.8     28.3-0.1
 10JAN2018     23.3-0.9     24.3-1.3     25.6-0.9     28.2-0.1
 17JAN2018     23.9-0.6     24.7-0.9     26.0-0.6     27.9-0.3
 24JAN2018     24.0-0.9     24.7-1.1     25.9-0.7     27.8-0.4
 31JAN2018     24.4-0.9     24.8-1.2     25.8-0.9     27.7-0.5
 07FEB2018     24.9-0.7     24.9-1.3     25.8-0.9     27.8-0.3
 14FEB2018     25.5-0.6     25.3-1.1     25.8-1.0     27.7-0.4

Nino 1.2 & Nino 3 warmed, Nino 3.4 steady. The SOI is at -16.7 for Feb 1-19. Something like a 90% shot it finishes the month between -6 and -18 based on plugging in historical February numbers for he rest of the month. Still think it will come up a fair amount by 2/28, but readings for 2/18 & 2/19 were still very negative. SOI has to be near +1 for the rest of tFebruary to not drop by 20 points from January.

There aren't any La Nina years since 1931 with a February SOI reading in the -6 to -18 range, so will be interesting to see what happens in March. The two nearest Nina status are probably February 1986 (-12.0) and February 1981 (-4.2).  I've been toying around with two blends and then imposing -SOI correlations on them: essentially warming up WA, cooling off the Southern US a bit, making the SW a bit wetter, drying out the OH/TN valleys relative to what the blend shows. Blending in 2005 with strong La Ninas seems like a way of doing that non-abstractly, since the SOI was -29.5 in Feb 2005, but you had a fairly cold Nino 1.2 in Jan-Feb 2005 (Feb 2005 was 25.16C, similar to the weeklies to date for Feb).

Something like this? Keep in mind, the weeklies seem to run 0.2-0.3C higher than the values CPC reports monthly for ONI. 

Feb	SOI	F 1.2	F 3.4
1968	9.1	24.70	25.68
1971	15.5	24.42	25.18
1971	15.5	24.42	25.18
1971	15.5	24.42	25.18
1981	-4.2	24.93	24.93
1981	-4.2	24.93	24.93
1981	-4.2	24.93	24.93
2005	-29.5	25.16	27.11
2006	-0.6	26.32	26.08
Mean	1.43	24.91	25.47

2018E  -9.0   25.10  25.65

[raindancewx]

I'm not a huge fan of the CFS, but its unlikely to be completely wrong on the next month at this range. Here is an attempt at "re-creating" the CFS forecast, in light of the huge -SOI, cold readings in February in Nino 1.2, Nino 3.4, with a couple years added for having similar conditions to winter, and following a major hurricane hitting TX, which seems to be an indicator of what the subtropical ridge does in the South in Feb/Mar.

I'm assuming the month CFS will continue to slowly change the exact dimensions on all of this, but Amarillo, TX has had something like 0.01" rain since mid-October, that seems like a good area for the high to be centered. NM/AZ have caught up a lot lately, as has the SE, as far as precipitation goes relative to normal. Here is a table explaining how I came up with the analogs - MH TX = Major Hurricane hit TX the year before March, and a 2,1,0,-1,-2 is used to determine how close winter was to what has been observed where I live for the "ABQ Obs" column, by looking at precipitation and highs each month for Dec/Jan/Feb. The SSTs for February are my estimates of the readings for February 2018. Locally, the SOI & Solar conditions peak as indicators in March, so I adjusted precipitation totals from the analogs since my solar conditions and SOI conditions were too high. March highs are warming here, but is correlated to the -SOI, so I adjusted the analogs in light of the lower SOI and more recent Marches being warm.

The SOI has been increasing more slowly than I expected, its still -15.9 for Feb 1-21. It needs to be over +3.3 for the rest of the month just to get above -11.1, the threshold for a 20 point drop.

[raindancewx]

SOI is finally coming up some, its at -10.4 for Feb 1-25, and looks positive 2/25 to 2/28, so it probably finishes around -6 to -9.

The recent re-emergence of warmth along the equator off Peru reminds me a bit of March 1997 visually, but its a bit earlier. The March 1997 SOI crash was to -7, which is similar to this month.

[raindancewx]

This event has transitioned rather nicely to a Modoki La Nina structure, with the core of the cold anomalies in Nino 3.4 now. 
Just like last year, that means warmth in the East, severe cold in the Northwest, particularly Montana. This is the first week
Nino 1.2 hasn't been below average since late July 2017. Been assuming Nino 1.2 would still be colder than normal in March, but
its probably going to be warmer than normal at this rate. 

The weeklies are centered on the date to the left, so we actually have 24-days of February now. In recent months, the weighted
weeklies have run 0.3C hotter than the monthly data, so it looks like 25.5C for Nino 3.4, and 25.1C for Nino 1.2, roughly. 
The 1951-2000 means for those zones on ERSST V.5 are 26.65C and 25.74C, respectively, so that's a pretty Nino 3.4.

February 2005 was actually pretty cold in Nino 1.2 (25.16C) and if Nino 3.4 really is 25.5C or so, that's the coldest reading in 
February in that zone since February 2008. In the last frame, the subsurface looks very warm, but it will be fighting a lot of 
cold at the surface. February 2005 was warm in Nino 3.4, but had a -29.5 SOI reading, so might be useful blending lightly with
some very cold La Ninas that had only a slightly positive SOI for March.       

   Nino1+2      Nino3        Nino34        Nino4
 Week          SST SSTA     SST SSTA     SST SSTA     SST SSTA
 03JAN2018     22.9-0.8     24.0-1.4     25.8-0.8     28.3-0.1
 10JAN2018     23.3-0.9     24.3-1.3     25.6-0.9     28.2-0.1
 17JAN2018     23.9-0.6     24.7-0.9     26.0-0.6     27.9-0.3
 24JAN2018     24.0-0.9     24.7-1.1     25.9-0.7     27.8-0.4
 31JAN2018     24.4-0.9     24.8-1.2     25.8-0.9     27.7-0.5
 07FEB2018     24.9-0.7     24.9-1.3     25.8-0.9     27.8-0.3
 14FEB2018     25.5-0.6     25.3-1.1     25.8-1.0     27.7-0.4
 21FEB2018     26.2 0.0     25.7-0.9     25.8-1.1     27.9-0.2

[AfewUniversesBelowNormal]

Tao/Triton map has maxed out subsurface of +4 in warm west. It's pretty rare and  the max here is +5 to +6, so this is a Moderate La Nina signal (Again La Nina subsurface signature is a flatter overall thermocline so higher west lower east)

[raindancewx]

Worth noting - if the MJO wave last year (big amplitude in 7 like this year, 2 to 3 transition around 3/1) helped warm the surface/end the Nina in Feb-Jun last year, the current MJO wave is similar. It might get stuck in two a little longer, but its a big wave nonetheless. The SOI was -2.2 last Feb as well, not super dissimilar from the -7 or so this year. Nino 1.2 has really warmed up a lot this week and is heading West through Nino 3/Nino 3.4 like a warm dagger.

As best I can tell, by raw DJF SSTs in Nino 3.4 and Nino 1.2, this event will end up very similar to 1954-55. All the DJF numbers are from the raw ERSST V.5 data. If a year is within 0.2C in either region, I included it one time. If you warm what the blend of the years shows by 1-2F nationally, it actually does look pretty similar to what the CFS has for March. I don't really like what the CFS has for precipitation, but the idea that we won't have a super-torch in the SW seems OK, given that we've never been more than +5F in March with the SOI under -4 in February, back to 1931. 

DJF	Nino 3.4	Nino 1.2
1950	25.41	23.67
1953	27.00	23.25
1954	25.56	23.34
1954	25.56	23.34
1955	25.22	23.09
1964	25.69	23.71
1973	24.63	23.20
1974	25.93	23.23
1975	24.90	23.28
1980	26.31	23.47
1984	25.55	23.64
1995	25.74	23.85
Mean	25.63	23.42
2017E	25.56	23.29

 

[AfewUniversesBelowNormal]

The west subsurface has stopped warming in the last 2 days, just as the NAO is going negative first the first time since November, and I think is the beginning of the end of the La Nina. It should be a weakening phase for the next month, the end of this warming phase should be pretty significant putting us in ENSO neutral conditions

[raindancewx]

The Canadian has slowed down the weakening of the La Nina some, but still thinks we go to El Nino conditions in Summer. The temperature outlook is warmer nationally than the CFS for March, outside the SE.

[raindancewx]

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/index/heat_content_index.txt
Equatorial Upper 300m temperature Average anomaly based on 1981-2010 Climatology (deg C)
YR    MON   130E-80W   160E-80W   180W-100W 
2017    7     0.13      0.15       0.16
2017    8    -0.19     -0.21      -0.40
2017    9    -0.45     -0.57      -0.79
2017   10    -0.54     -0.77      -0.97
2017   11    -0.41     -0.65      -0.84
2017   12    -0.31     -0.54      -0.75
2018    1     0.01     -0.17      -0.16
2018    2     0.27      0.06      -0.14