Winter 2020 Weather Outlook

This winter seems to one of those years where there aren’t many solid clues as to predict what sort of weather pattern may emerge in Southern California during the next few months. The cool, wet weather pattern which suddenly emerged in November continued into December as several cold-core storm systems visited the state. Will it continue in the remaining winter months?

The Niño region saw significant warming in December which may negate any chance of seeing an El Niño from developing this season. The majority of long range models had been consistent in showing well below normal precipitation this winter across California. The axis of lowest precipitation compared to normal has shifted northward into Northern CA, bringing the driest conditions into the Pacific Northwest. It remains to be seen whether the strong jet stream that we’ve seen this winter will continue to be the biggest player in the weather, or if a blocking pattern will eventually win out.

Long range models are still keen on the concept of drier than average weather the rest of the winter, with some of the greater deficits occurring in January and February but forecaster confidence remains lower than normal. Temperature outlooks further down the line are a bit clearer, cut with a high likelihood of warmer than normal temperatures through spring.

Widespread, significant precipitation occurring near the winter solstice is usually enough to keep large fire potential low in ensuing weeks and this year should be no exception. The mountains have near or above normal snowpack for this time of year while lower elevations are seeing rapid growth of seasonal grasses. If the weather turns warm and dry for a period of time during the next month or two, fire spread should be limited to windy periods and confined to elevations above seasonal grass growth.

Large fire potential may rise to an above normal potential by April over Southern California. Last year was a very quiet fire season across the western U.S. This summer may be more active across the West and there may be more completion outside of the region for resources. Look for higher preparedness levels nationally with an earlier onset to the 2020 fire season overall. Locally, the highest potential this season (and perhaps for many seasons to come) will likely be in the Sierra Foothills due to a dense stand of bug killed timber. It is too soon to predict whether this will be an active monsoon season, but since storms were so infrequent last year, there will probably be a greater r risk of lightning-generated ignitions compared to 2019.

Summary

• Temperatures Above Normal through March
• Winter Precipitation Below Normal rest of winter into early spring
• Near Normal number of offshore wind events January
• Early onset of spring “grassfire season” possible in April