El Nino contributed to Florida's cool winter, a summer La Nina could influence hurricane season

If it has seemed a bit cooler than usual this winter, it is not just your imagination. For example, in the first 21 days of February, 71% of those days were cooler than average in Tampa, 67% were cooler than average in Ft. Meyers, and 62% of those February days were cooler than average in Jacksonville. This winter, the ocean circulation pattern known as ENSO, or the El Nino Southern Oscillation has been in the El Nino phase.

When in an El Nino phase, the impacts in Florida actually are different from much of the nation. That's because the southern branch of the jet stream is more active in an El Nino winter, driving more cold fronts into Florida. In a Florida winter, during an El Nino pattern, the temperatures are cooler than average and precipitation is higher. Due to the lag between ocean patterns and the atmosphere, the strong measured El Nino in January shows up in February data.

The extended forecast for March shows this transition underway, with Florida and the Gulf Coast remaining a bit cooler than average and wetter. The El Nino indicators measured were stronger in January, and have weakened in February and are forecast to fully reverse this summer and the pattern will move into the La Nina phase.

The Climate Prediction Center has issued a La Nina Watch, meaning a transition to La Nina is expected to occur over the next several months into the summer, that will mean less wind shear in tropical waters. The lack of strong upper level winds during La Nina summers to disrupt the flow around developing tropical storms means higher numbers of storms, and storms that could grow into larger, more powerful hurricanes. The combination of warmer tropical waters and more favorable La Nina upper level winds expected this summer are indicators that we can expect another active hurricane season. That does not need that Florida will necessarily experience numerous major hurricanes this season, but it does mean that we will be more likely to see higher numbers of stronger tropical cyclones in the Atlantic basin, and as every Floridian knows, it only takes one storm.