Oct. 16, 2020: La Niña’s reign continues; 85% chance it will last through the winter
As reported in NOAA’s ENSO Blog, “La Niña’s reign continues in the tropical Pacific, with an approximately 85% chance of lasting through the winter. Forecasters currently think this La Niña will be on the stronger side.”
This week NOAA released its winter outlook and are expecting a typical La Niña pattern, which is: a cooler and wetter northern tier of the country, while the southern tier is expected to be warmer and drier. This could have big implications for the areas in New Mexico, and West and Far West Texas, which are currently sitting in drought.
Below is map of how December through January precipitation deviates from average (i.e. the anomaly) during weak La Niña events. The years considered are listed under the heading. As noted above, though, NOAA expects a relatively strong event so some of these patterns may not hold up. One thing about La Niña events (Los Niñas?) that should be mentioned, however, is that while they have a signature pattern, not every La Niña behaves like a good La Niña should. So there could be some surprises.
During the last La Niña, we looked at how recent events have affected the winter wheat yield. Unfortunately, the data from USDA gets a bit spotty in the 00s, but you can see there is a slight “La Niña” pattern between Oklahoma and Texas. This roughly corresponds with the weak La Niña precipitation map above.
The map below shows the latest seasonal drought outlook. NOAA is expecting drought will intensify in the western half of the country and develop in the Plains through the winter. While they paint a pretty bleak picture, we would point out again every La Niña event is different, and things often unfold in a way that will surprise you and even the forecasters.
I heard a story about a forecast meeting NOAA held several years ago for a few states in the Southeast. It was a similar scenario: A La Niña was setting up and the forecasters were making some dire predictions that the winter was going to be a warm and dry. It turned out Georgia experienced one of its colder winters on record. In fact, Atlanta had a White Christmas that same year. The first since 1881! Guessing those forecasters were put into the forecaster witness protection program. A warm and dry winter indeed…