COLUMBUS, Ohio (WCMH) — The summer outlook from NOAA’S Climate Prediction Center predicts warmer-than-average temperatures across virtually all of the country, except along the West Coast.
The Ohio Valley is expected to have a warm summer (June-August), with temperatures likely averaging 1-2 degrees Fahrenheit above normal. Much-above-normal temperatures are predicted in the Northeast, and from the Intermountain West to the western Plains, which is concerning because of the threat of continuing drought and rampant wildfires in the Western states.
Rainfall forecasts are more challenging in the summer because thunderstorms are affected by local patterns, since the upper-level flow is comparatively weak. Given the prevailing precipitation distribution in spring with ample soil moisture, there is a likelihood of at least slightly above-normal rainfall in the upper Ohio Valley.
Rainfall is expected to be deficient in the central states and much of the West through the first half of summer, prior to the onset of the North American monsoon, which brings sporadic rain to portions of Southwest, though not reaching the interior Far West.
The summer weather pattern will continue to be affected by cooler-than-average sea surface temperatures in the central and eastern tropical Pacific Ocean referred to as La Niña.
A weaker jet stream flow over the Atlantic influenced by La Niña increases the risk of hurricanes over the western Atlantic Basin due to decreased wind shear aloft.
According to NOAA’s Climate Prediction Center, there is a 59% chance La Niña will hang around through August, and a 50%-55% chance of an even longer run well into the fall, which would be a rare three-year period of below-normal sea surface temperatures in the equatorial eastern Pacific that commenced in 2020.
La Niña develops in relation to fluctuations in the surface air pressure pattern between Tahiti and Australia that causes warm water to flow westward away from the coast of South America, which allows deep cold currents to reach the surface and provide nutrients for aquatic life in coastal Peru.
In the spring, severe weather outbreaks are more common in the Central and Southern states during La Niña, where air masses frequently clash and storm systems are intensified by a strong jet stream from the Southwest to the Great Lakes.
The opposite climate pattern features a warm sea surface temperatures, classified as El Niño, which presents with a different climatic response in the Lower 48 states.