2024 ENSO= BoM / CPC have La Niña watch in effect / CPC June update on the 13th

[DorkyMcDorkface]

Can you tell La Niña is coming?

[Kingarabian]

Strong westerlies over the equatorial IO is a great indicator.

[Woofde]

Equatorial SOI has reached neutral levels. This agrees with the traditional SOI metric, which has also just about returned to baseline. It looks like we've reached true neutral by most atmospheric and oceanic metrics. Now it's time to see how deep the transition goes.

[cycloneye]

CPC weekly update has niño 3.4 in warm neutral at +0.2C, but they still have not declared that el niño has ended as they will do it on June 13th.

[cycloneye]

The ENSO plume consensus of all the dynamic models has weak la niña for the peak of the season ASO.

https://iri.columbia.edu/our-expertise/ ... -sst_table

[LarryWx]

The ENSO plume consensus of all the dynamic models has weak la niña for the peak of the season ASO.

https://iri.columbia.edu/our-expertise/ ... -sst_table

https://i.imgur.com/xaGLURL.jpeg

Indeed, the dynamic model avg ONI for ASO is -0.557, low end weak La Niña. That means that the implied RONI prog for ASO is in the low to mid moderate La Niña range…-1.0 to -1.2. For the CONUS per analogs I’ve studied, the -1.0 would be higher risk vs normal for FL Atlantic coast and up E coast vs a -1.2 implying highest risk in CONUS vs normal further west on Gulf coast with nearer normal E coast of FL and up E coast of US. The general idea is for the highest risk for US E coast including FL vs its normal risk to be if ASO RONI is weak to low end moderate La Niña vs that highest US risk vs normal shifting westward to Gulf coast if ASO RONI is middle grade moderate to strong La Niña. If I’m not mistaken, that normal risk to US Gulf coast is somewhat higher than normal risk to US E coast. Someone please correct me with data if this isn’t correct.

[cycloneye]

The ENSO plume consensus of all the dynamic models has weak la niña for the peak of the season ASO.

https://iri.columbia.edu/our-expertise/ ... -sst_table

https://i.imgur.com/xaGLURL.jpeg

Indeed, the dynamic model avg ONI for ASO is -0.557, low end weak La Niña. That means that the implied RONI prog for ASO is in the low to mid moderate La Niña range…-1.0 to -1.2. For the CONUS per analogs I’ve studied, the -1.0 would be higher risk vs normal for FL Atlantic coast and up E coast vs a -1.2 implying highest risk in CONUS vs normal further west on Gulf coast with nearer normal E coast of FL and up E coast of US. The general idea is for the highest risk for US E coast including FL vs its normal risk to be if ASO RONI is weak La Niña vs that highest US risk vs normal shifting westward to Gulf coast if ASO RONI is moderate to strong La Niña. If I’m not mistaken, that normal risk to US Gulf coast is somewhat higher than normal risk to US E coast. Someone please correct me with data if this isn’t correct.

What is the risk for the Caribbrean with weak La Niña?

[LarryWx]

The ENSO plume consensus of all the dynamic models has weak la niña for the peak of the season ASO.

https://iri.columbia.edu/our-expertise/ ... -sst_table

https://i.imgur.com/xaGLURL.jpeg

Indeed, the dynamic model avg ONI for ASO is -0.557, low end weak La Niña. That means that the implied RONI prog for ASO is in the low to mid moderate La Niña range…-1.0 to -1.2. For the CONUS per analogs I’ve studied, the -1.0 would be higher risk vs normal for FL Atlantic coast and up E coast vs a -1.2 implying highest risk in CONUS vs normal further west on Gulf coast with nearer normal E coast of FL and up E coast of US. The general idea is for the highest risk for US E coast including FL vs its normal risk to be if ASO RONI is weak La Niña vs that highest US risk vs normal shifting westward to Gulf coast if ASO RONI is moderate to strong La Niña. If I’m not mistaken, that normal risk to US Gulf coast is somewhat higher than normal risk to US E coast. Someone please correct me with data if this isn’t correct.

What is the risk for the Caribbrean with weak La Niña?

I honestly don’t know. Plus even if I knew, it probably would vary based on what portion of the Caribbean is being analyzed since it is pretty large. But if I were to make a wild guess based on common storm tracks, I’d say that the US E coast risk would probably be highest vs its normal when NE Caribbean risk is highest vs its normal. I’d also guess that the threat to the US Gulf coast would be highest vs its normal when the threat to the NW Caribbean is at its highest vs its normal.
So, my wild guess is that a weak to low end moderate RONI based La Niña during ASO would mean higher than normal risk to NE Caribbean but a stronger La Niña would perhaps shift that highest risk vs normal further W in the Caribbean.

[cycloneye]

Indeed, the dynamic model avg ONI for ASO is -0.557, low end weak La Niña. That means that the implied RONI prog for ASO is in the low to mid moderate La Niña range…-1.0 to -1.2. For the CONUS per analogs I’ve studied, the -1.0 would be higher risk vs normal for FL Atlantic coast and up E coast vs a -1.2 implying highest risk in CONUS vs normal further west on Gulf coast with nearer normal E coast of FL and up E coast of US. The general idea is for the highest risk for US E coast including FL vs its normal risk to be if ASO RONI is weak La Niña vs that highest US risk vs normal shifting westward to Gulf coast if ASO RONI is moderate to strong La Niña. If I’m not mistaken, that normal risk to US Gulf coast is somewhat higher than normal risk to US E coast. Someone please correct me with data if this isn’t correct.

What is the risk for the Caribbrean with weak La Niña?

I honestly don’t know. Plus even if I knew, it probably would vary based on what portion of the Caribbean is being analyzed since it is pretty large. But if I were to make a wild guess based on common storm tracks, I’d say that the US E coast risk would probably be highest vs its normal when NE Caribbean risk is highest vs its normal. I’d also guess that the threat to the US Gulf coast would be highest vs its normal when the threat to the NW Caribbean is at its highest vs its normal.
So, my wild guess is that a weak to low end moderate RONI based La Niña during ASO would mean higher than normal risk to NE Caribbean but a stronger La Niña would perhaps shift that highest risk vs normal further W in the Caribbean.

Thanks Larrywx. Interesting the shift from one area (NE Caribbean) to (NW Caribbean) depending on La Niña strengh.

[LarryWx]

What is the risk for the Caribbrean with weak La Niña?

I honestly don’t know. Plus even if I knew, it probably would vary based on what portion of the Caribbean is being analyzed since it is pretty large. But if I were to make a wild guess based on common storm tracks, I’d say that the US E coast risk would probably be highest vs its normal when NE Caribbean risk is highest vs its normal. I’d also guess that the threat to the US Gulf coast would be highest vs its normal when the threat to the NW Caribbean is at its highest vs its normal.
So, my wild guess is that a weak to low end moderate RONI based La Niña during ASO would mean higher than normal risk to NE Caribbean but a stronger La Niña would perhaps shift that highest risk vs normal further W in the Caribbean.

Thanks LarryWx. Interesting the shift from one area (NE Caribbean) to (NW Caribbean) depending on La Niña strengh.

You’re welcome. Keep in mind that’s just a wild guess and it is a guess vs each area’s normal. It isn’t based on actual storm data. Someone could look at the worst storms to hit each section of the Caribbean during ASO RONI based La Niña over a multi-decadal long period and see if there’s a tendency for a shift for different strengths of La Niña. That would probably be time consuming and still may not yield a definitive result.

[cycloneye]

Found a good graphic of U.S CONUS landfall with the different strenghs of La Niña, Neutral and El Niño.

[LarryWx]

Found a good graphic of U.S CONUS landfall with the different strenghs of La Niña, Neutral and El Niño.

https://i.imgur.com/cU5V3Ev.jpeg

Thanks, Luis!

After seeing this, I decided to do an analysis of CONUS landfalls for RONI ASO -0.50 to -1.00 vs sub -1.00. E = east coast and G = Gulf coast including FL Keys; if storm landfalled on both as a H, I counted it as 1/2 E and 1/2 G (1995’s Erin and 2022’s Ian)

ASO RONI -0.50 to -1.00: every season at least 1
1954: 3 (3E)
1955: 2 (2E)
1964: 4 (2E, 2G)
1970: 1 (1G)
1983: 1 (1G)
1995: 2 (0.5E, 1.5G)
1999: 3 (1E, 2G)
2011: 1 (1E)
2017: 3 (3G)
2021: 2 (2G)
AVG: 2.20 (0.95E, 1.25G)


ASO RONI sub -1.00: less active avg despite 2020
1973: 0
1975: 1 (1G)
1988: 1 (1G)
1998: 3 (1E, 2G)
2007: 1 (1G)
2010: 0
2016: 2 (1E, 1G)
2020: 6 (1E, 5G)
2022: 2 (1.5E, 0.5G)
AVG: 1.78 (0.50E, 1.28G)

Analysis of ASO RONI wk vs mod+:
-sig. more CONUS H landfalls (100%/70% had 1+/2+)
-sig. more E coast landfalls (60%/30% had 1+/2+)
-slightly fewer G coast landfalls due to 2020 being active
-E being nearly as active as G for wk is relatively high for E
-2020 ASO is mod+ per RONI but is only wk per ONI

H tracks:
https://www.nhc.noaa.gov/data/

RONI: https://www.cpc.ncep.noaa.gov/data/indi ... .ascii.txt

[TheAustinMan]

I honestly don’t know. Plus even if I knew, it probably would vary based on what portion of the Caribbean is being analyzed since it is pretty large. But if I were to make a wild guess based on common storm tracks, I’d say that the US E coast risk would probably be highest vs its normal when NE Caribbean risk is highest vs its normal. I’d also guess that the threat to the US Gulf coast would be highest vs its normal when the threat to the NW Caribbean is at its highest vs its normal.
So, my wild guess is that a weak to low end moderate RONI based La Niña during ASO would mean higher than normal risk to NE Caribbean but a stronger La Niña would perhaps shift that highest risk vs normal further W in the Caribbean.

I made the following plot using the ASO temperature anomaly in the Nino3.4 region relative to the preceding 30-year period as thresholds for La Niña and El Niño. The shading/contours indicate areas where there is more or less ACE for a particular group of years than average. In general, when accounting for only the ENSO state, there does appear to be a slight southwestward shift in where activity tends to be most above average as one turns up the La Niña intensity. Stronger La Nina years are most anomalous in the Western Caribbean and Yucatan Channel region, while weaker La Nina years are most anomalous around the Bahamas.

Of course, this accounts for only ENSO state and does not account for AMO, which is certainly a very strong influence on Atlantic activity (2005, for instance, would count as very slightly warm neutral in this particular computation).

Source: Created using Python. Data from IBTrACS. Excludes 2023.


And, restricting the data for only 1950 to present:

Source: Created using Python. Data from IBTrACS. Excludes 2023. 1950-present only.

[LarryWx]

I honestly don’t know. Plus even if I knew, it probably would vary based on what portion of the Caribbean is being analyzed since it is pretty large. But if I were to make a wild guess based on common storm tracks, I’d say that the US E coast risk would probably be highest vs its normal when NE Caribbean risk is highest vs its normal. I’d also guess that the threat to the US Gulf coast would be highest vs its normal when the threat to the NW Caribbean is at its highest vs its normal.
So, my wild guess is that a weak to low end moderate RONI based La Niña during ASO would mean higher than normal risk to NE Caribbean but a stronger La Niña would perhaps shift that highest risk vs normal further W in the Caribbean.

I made the following plot using the ASO temperature anomaly in the Nino3.4 region relative to the preceding 30-year period as thresholds for La Niña and El Niño. The shading/contours indicate areas where there is more or less ACE for a particular group of years than average. In general, when accounting for only the ENSO state, there does appear to be a slight southwestward shift in where activity tends to be most above average as one turns up the La Niña intensity. Stronger La Nina years are most anomalous in the Western Caribbean and Yucatan Channel region, while weaker La Nina years are most anomalous around the Bahamas.

Of course, this accounts for only ENSO state and does not account for AMO, which is certainly a very strong influence on Atlantic activity (2005, for instance, would count as very slightly warm neutral in this particular computation).

Source: Created using Python. Data from IBTrACS. Excludes 2023.
https://i.imgur.com/cNUsnTz.png

And, restricting the data for only 1950 to present:

Source: Created using Python. Data from IBTrACS. Excludes 2023. 1950-present only.
https://i.imgur.com/GgXtM7j.png

Fantastic images! This clearly also shows that for the CONUS overall based on ASO ONI, weaker Niña is on average the most dangerous, especially FL to NC, though weaker vs stronger La Niña is close in TX. Would it be possible for you to do the same 6 images for RONI ASO instead of ONI ASO? If not for the 6, could you do just weaker RONI ASO vs stronger RONI ASO? You’d only be able to go back to 1950 since that’s as far back as RONI goes.

RONI:
https://www.cpc.ncep.noaa.gov/data/indi ... .ascii.txt

[LarryWx]

I honestly don’t know. Plus even if I knew, it probably would vary based on what portion of the Caribbean is being analyzed since it is pretty large. But if I were to make a wild guess based on common storm tracks, I’d say that the US E coast risk would probably be highest vs its normal when NE Caribbean risk is highest vs its normal. I’d also guess that the threat to the US Gulf coast would be highest vs its normal when the threat to the NW Caribbean is at its highest vs its normal.
So, my wild guess is that a weak to low end moderate RONI based La Niña during ASO would mean higher than normal risk to NE Caribbean but a stronger La Niña would perhaps shift that highest risk vs normal further W in the Caribbean.

I made the following plot using the ASO temperature anomaly in the Nino3.4 region relative to the preceding 30-year period as thresholds for La Niña and El Niño. The shading/contours indicate areas where there is more or less ACE for a particular group of years than average. In general, when accounting for only the ENSO state, there does appear to be a slight southwestward shift in where activity tends to be most above average as one turns up the La Niña intensity. Stronger La Nina years are most anomalous in the Western Caribbean and Yucatan Channel region, while weaker La Nina years are most anomalous around the Bahamas.

Of course, this accounts for only ENSO state and does not account for AMO, which is certainly a very strong influence on Atlantic activity (2005, for instance, would count as very slightly warm neutral in this particular computation).

Source: Created using Python. Data from IBTrACS. Excludes 2023.
https://i.imgur.com/cNUsnTz.png

And, restricting the data for only 1950 to present:

Source: Created using Python. Data from IBTrACS. Excludes 2023. 1950-present only.
https://i.imgur.com/GgXtM7j.png

I didn’t catch this before. Why do you have only 4 stronger (sub -1) La Niña seasons per ASO since 1950 and which 4? What source did you use for Nino 3.4 SSTa? Per this ONI table, I see 8 sub -1.0 during ASO:

https://origin.cpc.ncep.noaa.gov/produc ... ONI_v5.php

Thanks in advance.

[cycloneye]

The new kid of the block is relative niño 3.4 index. El Niño has been out a few weeks ago, but officially, is still alive.

 https://x.com/BenNollWeather/status/1793235394219434190

[LarryWx]

The new kid of the block is relative niño 3.4 index. El Niño has been out a few weeks ago, but officially, is still alive.

 https://x.com/BenNollWeather/status/1793235394219434190

Thanks, Luis. This is the first time I’ve ever seen a model prog for RONI! It’s showing RONI-ONI to be -0.67 in May and -0.55 in Oct. Based on this graph, it’s showing a prog of ASO ONI to be ~-0.60 (weak La Niña) but ASO RONI to be ~-1.15 (moderate La Niña), a truer reflection of the predicted strength of La Niña since it is negating the surrounding tropical waters’ warming.

[skyline385]

Relative ONI seems to be the same as SSTa - Global mean SSTa, which while introduced 2-3 years ago has so far failed to pick up. They make sense in a global warming world and I am in support of using them but we do need some actual studies on relative vs absolute indices and which are more accurate in predicting the atmospheric response and eventually for the official authorities to start using them. Until then, unfortunately they remain just one of out many indices which are used speculatively.

[TheAustinMan]

I didn’t catch this before. Why do you have only 4 stronger (sub -1) La Niña seasons per ASO since 1950 and which 4? What source did you use for Nino 3.4 SSTa? Per this ONI table, I see 8 sub -1.0 during ASO:

https://origin.cpc.ncep.noaa.gov/produc ... ONI_v5.php

Thanks in advance.

I probably used a different methodology. My years were based on SST anomaly relative to the preceding 30 years (so, for example, 1955 would be relative to 1925-1955). In that case, the four years that met criteria were 1973, 1975, 1988, and 2010. I didn't use the ONI page for that selection of years, but used ERSSTv5 SST data instead.

Fantastic images! This clearly also shows that for the CONUS overall based on ASO ONI, weaker Niña is on average the most dangerous, especially FL to NC, though weaker vs stronger La Niña is close in TX. Would it be possible for you to do the same 6 images for RONI ASO instead of ONI ASO? If not for the 6, could you do just weaker RONI ASO vs stronger RONI ASO? You’d only be able to go back to 1950 since that’s as far back as RONI goes.

RONI:
https://www.cpc.ncep.noaa.gov/data/indi ... .ascii.txt

Sure thing.

[Kingarabian]

It looks like a classic -PDO is setting up. Something we have not seen in a while despite the index being negative for the past few years. Waters are not just warm east of Japan but also NE of Hawaii. As well as a cold horseshoe off of NWAmerica.