The latest sea surface temperature anomaly map.

You can see the El Niño weakening, and the evidence of La Niña building. There is also quite a bit of cooling in the north Pacific and from the Baja to Hawaii. That “cold horseshoe” is likely going to mean a PDO (Pacific Decadal Oscillation) that gets more and more negative/cold. That is not a good sign as we move out of spring and into summer…

The long range models seem to agree with me. I have no doubt we are going to La Niña, and it could be a fairly strong one. I think the only question lies in how fast it comes on… Here are the latest probabilities from NOAA and the Climate Prediction Center…

You can see that it has us locked in with La Niña percentages of 60% or greater starting in June/July/August.

Here is a look at the full NMME model precipitation anomaly forecast. This model is aggressive in bringing the La Niña on quickly and strongly. So, factor that in with it’s relatively drier than average forecast for many areas of the central and southwest US.

NMME Model Precipitation Anomaly Forecast April – October

You can see that NMME is pretty aggressive about bringing on the dryness after we get out of May, and possibly early June for some. This is especially true for the Southern Plains and Desert Southwest. There would be heat issues too…possibly starting up as soon as June, but certainly maxing out in July/August/September. As I have been saying for the past several months, the time between now and June is critical. After we get past June, and the monsoon likely ends up either severely diminished or a significant failure, it doesn’t leave much room to break the pattern. La Niña will likely linger into the first one-third of 2025, which leads to another set of issues when trying to break the dry/droughty pattern.

1) Could this be wrong? Sure…I just don’t have any current or historical evidence to think so. It is a prepare for the worst and hope for the best scenario…in my opinion.

2) Will there still be rain? Of course there will… But with this setup, it just makes it less frequent and meaningful. Also, the farther west you live, the drier it will likely end up. The hurricane season will likely be active, which accounts for the wetter than average bias to parts of Texas and the Gulf Coast this summer. 

3) Wait, the monsoon was pretty amazing during the summers that La NIña was around…why not this year? The exceptionally warm water off the west coast of Africa is known as the positive/warm Atlantic Meridional Mode. It was present last year, and the monsoon disappointed. That region is even warmer than last year, and I see no reason for it to change. This is historically a bad sign for the monsoon. Even the models see a monsoon failure happening… This is significant for western parts of the region.

Plenty to watch and analyze in the coming days, but I fear the deck is stacked against many of us for the second half of 2024. Could the active tropical storm and hurricane season offset this trend? Sure, but those storms have to come in at the right angle to help us. If they shear east, then they are no help at all…