In simple terms, La Nina is when the waters in the Pacific at the equator are cooler than normal. The opposite, El Nino, indicates that Pacific Ocean water is warmer than normal. These fluctuate from year to year, lasting several months at a time and we can also see neutral conditions when neither is prevalent. Here’s the example of La Nina and El Nino:
And as far as which one we see more often, it’s 50/50...since record keeping from 1950, we’ve had 25 El Ninos and 24 La Ninas! El Nino can help us with our hurricane season producing strong winds from the Pacific across Central America which tear up tropical storms that are forming in the Caribbean. In fact, because we have not had an El Nino this summer we’ve had another above normal hurricane season this year at 20 storms/7 hurricanes/4 majors and counting.
We had a La Nina last year and although it left us in late spring, it’s back for another round this year! Known as “double dipping,” we don’t usually see two years in a row of La Nina, but all models point to another one already occurring and lasting through spring. Follow the red line below and you’ll see it’s well below the 0° line which is the neutral line:
So what does that mean to us? Well, usually a La Nina winter brings us a drier than normal, warmer than normal winter with the Jet Stream cutting the country in half. The cold, wet winter shows up in the northern U.S. and Canada:
So what about last year?
Last winter, we had a La Nina but when we think of earlier this year we certainly focus on the cold February blast that proved not only miserable, but deadly. We don’t think of drier and warmer than normal! But it was! Take a look at January through March as far as average highs and lows and rainfall (I’ve rounded the temps for simplicity):
All of these months were drier than normal, while January and March were above normal for average highs. In fact, we only had one freezing day in January and hit 78° twice that month. February actually started with 80° on 2/4 and lots of 60s and 70s the first ten days. Of course, the bottom fell out on Valentine’s Day:
So what happened? Actually the polar vortex usually keeps the cold air locked up at the north pole, but an influx of warm air weakened it allowing the cold air to seep southward into the United States, so we had that one week exception of very cold air that moved into Texas. You can thank climate change for that. But it is the exception, not the rule. Despite a cold outbreak possibility, I’m forecasting a dry, warm winter.
For now, here is what counts: it’s the weekend and this big cold front moving through this afternoon promises some exceptional weather the next several days. Enjoy and GO ASTROS!!