KNOXVILLE, Tenn. (WATE) — Last week the National Oceanic and Atmospheric Administration (NOAA) released their forecast for an upcoming La Niña event and head into another La Niña winter season.
La Niña is a period of below-average sea surface temperatures across the East-Central equatorial Pacific. It brings warmer than normal winters for the southeast and episodes typically last 9 to 12 months. However, it can last as long as a couple of years.
La Niña means “little girl” in Spanish and it usually develops late in the year around Christmastime. In East Tennessee, La Niña often means wetter and warmer than average winters. In fact, the previous 10 of 13 events have been this way.
The National Weather Service declared La Niña conditions last week and there is an 87% chance that La Niña will persist through the winter. The official winter forecast will be released on Thursday, Oct. 21.
La Niña also affects the wind flow at the upper levels of the atmosphere around the globe. It will typically create a large high-pressure area over the eastern pacific. This will act as a block that deflects the polar jet stream southward, then the jet stream will move eastward. Meaning the cold air is locked to the north, leaving the warmer air and wet weather along those jetstream winds moving from west to east through the eastern half of the country.
