Forecaster Sees a Ho-Hum Winter

One of the nation’s pioneer researchers in long-range weather forecasting on Monday predicted normal wintertime temperatures and precipitation for much of the nation in the next three months, including Southern California.

Jerome Namias, head of the climate research group at UC San Diego’s Scripps Institution of Oceanography, expects a colder-than-normal winter only for the northern third of the United States, from Oregon to the Great Lakes region. He predicted warmer-than-average temperatures for the southeastern states.

Heavier-than-normal precipitation is forecast along a swath running from central Texas through the Southeast along the Atlantic Seaboard into Maine, as well as in Central and Northern California, Nevada and Utah. Normal amounts of rain and snow can be expected in Southern California and the Western Plateau states, the Central Plains and much of the Midwest. The extreme Northwest, the eastern Northern Plains and Great Lakes states and southern Florida can look for lower-than-average precipitation.

Namias said in an interview Monday that his annual 90-day winter forecast is only an experimental prediction and represents the average of national conditions from December to February, not a detailed weekly or daily breakdown.

He developed monthly and seasonal predictions as chief of the National Weather Service extended forecast division in the late 1960s.

His former protege, Donald Gilman, now heads the service’s predictions branch and issued his own winter forecast Friday in an ongoing “friendly competition” between Washington and La Jolla.

The two forecasts predict similar weather for Southern California but differ for several other regions. Namias sees more precipitation in Central California and warmer temperatures in the Midwest and Southeast than Gilman.

Part of the competition comes in the way that the two centers interpret the data from satellite, ocean-buoy and other sensors picking up temperature and wind conditions across the Pacific.

Namias bases his group’s interpretation primarily on the interaction of surface water temperatures and wind patterns in the North Pacific, relying on the ocean temperatures as indicators of changes over North America.

Gilman relies more on upper wind currents and atmospheric pressure patterns going back decades, as well as factoring in recent weather anomalies in the last several seasons that can be expected to continue.

The key, in both cases, is how far the westerly jet streams, which carry storms across the continent, dip down from polar regions and what path they will take.