How El Niño may impact tornado, hail frequency in spring
AUSTIN (KXAN) -- As El Niño continues into at least the early spring, it’s worth looking into its influence on spring weather in Central Texas.
The latest outlook from the Climate Prediction Center has El Niño solidly favored during the bulk of our severe weather season, which runs from March through early June.
The March-May ENSO (El Niño Southern Oscillation) forecast continues to favor El Niño over any other phase.
Typically, there are more weather pattern connections to the winter months in the Northern Hemisphere during La Niña or El Niño periods, but severe weather may be impacted in the spring.
NOAA referenced a study that was published in April 2015 in Nature Geoscience by authors John Allen, Michael Tippett and Adam Sobel, which documented decreasing severe weather in Central Texas during El Niño spring months.
In the image below, you can see the decreasing (brown) or increasing (purple) frequency of tornadoes or hail during El Niño springs (March-May) on the left, versus La Niña springs on the right.
While El Niño shows a decrease in both hail and tornadoes in Central Texas during the spring, the opposite is true in La Niña spring months. The frequency of hail storms increases more dramatically than the increase in the number of tornadoes in La Niña springs, but they both become more common.
The reason for the change? Typically during El Niño spring months, the surface winds that carry the warm and humid air from the Gulf of Mexico are weaker. This lowers the temperature and humidity gradients near the Southern Plains and tends to discourage incidents of severe weather.
Spring forecast
Meteorological spring begins March 1 and continues through the end of May. The latest three-month outlook from the Climate Prediction Center favors near normal temperatures and near normal to slightly below normal rainfall, with drier weather favored to the west.
Still, just because the overall trend points toward fewer tornadoes and hail events during El Niño springs, it doesn't mean we won't have those at all.