Prepare for Potential Big Rainy Event in December

Last winter, San Diego County saw above-normal rainfall throughout the county. What can we expect this winter season and further out?

The National Weather Service wants us to be a “Weather Ready Nation.” So, meteorologists based in the Rancho Bernardo office talked to city and county representatives including firefighters and law enforcement this week to prepare them for weather-related hazards this season.

First of all, you may have already heard, we are experiencing a weak to moderate La Nina weather event which generally means less rain here in San Diego and more in other regions like the Pacific Northwest. However, forecasters pointed out that last year we actually had more rain than usual and it was also a La Nina event. This year, they are comparing models that show what has occurred historically in San Diego during years when there have been consecutive La Nina events to predict the winter outlook.

Alex Tardy, warning coordination meteorologist for the National Weather Service, said that just because the season started off wet in November, it doesn’t mean that it will continue. Data seems to show there will be an average season for rainfall, but we can still have some big storms that would impact the county in December or January.

“There’s still a threat of a big rainfall event this season,” Tardy said. “These types of scenarios are more common in a weak La Nina or neutral event.”

Tardy explained that one 4- to 10-day period of intermittent heavy rainfall is all it would take to cause significant flooding and hazards in the county.

Temperatures are expected to be cooler than normal this winter with increased chances of frost or freeze in December through mid February. Low snow levels are also predicted during several storms.

After one or possibly two heavy rainfall events this winter and a few smaller storms, it is likely that February through March will be drier than normal.

“We’re not out of the woods with wildfires,” Tardy said. “If we enter into the predicted dry weather, an early fire season could be in the making this spring.”

If this prediction holds true, the seasonal grasses and plants that come up after the rains could quickly dry up and become fuel for wildfires.

While Tardy offered the long-range outlook for first responders, he said the public can also take this information and prepare at home.

• Residents can get sandbags if flooding typically occurs in your area.
• Clean out storm drains on your property.
• Never cross a flooded intersection or stream in a vehicle or on foot. The water may be deeper or moving faster than it appears.
• Keep up with the yard work this spring by clearing away dead and dry vegetation before it becomes a hazard.

National Weather Service meteorologist Mark Moede also provided the city and county with an overview of resources for weather information starting with their redesigned web site at weather.gov/sandiego. The site was reorganized to be more user-friendly and has new front page features. It retains a “point and click” interface meaning people can click anywhere on the map and get current weather conditions and a forecast for that point. The site also offers a “Weather Story” thumbnail for quick updates, headlines that quickly state the latest news, and popular links in a new toolbar tab menu.

Chula Vista emergency services coordinator Tom Leonard, who attended the meeting, said the forecast information and online tools are a great resource for the region.

“If we have a weather event, it’s more helpful to get fast information for my city,” Leonard said.