The official “rainy season” for Southern California started on October 1 and continues through April 30, 2020. Rainfall events typically begin to arrive in October and continue with more frequency as we get into November and December. That said, we are more than halfway through October and there isn’t much rain in sight through Halloween. With the current above average temperatures forecast to continue well into fall, there may be a late onset of rainfall events for Southern California. Here is a summary of the winter weather outlook through the end of 2019:
- Temperatures slightly above normal, especially across inland areas.
- Chance of a delayed start to the “rainy season” with a likelihood of below normal rainfall this winter.
- Near normal to slightly above number of offshore wind events expected through December.
The three-month seasonal temperature and precipitation outlooks shown below from the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center generally favor above-average temperatures across much of the United States, including the Southwest, and below normal to normal precipitation for California.
What to do now to prepare for when it starts raining this winter?
Businesses and municipalities need to implement standard rainfall contingency plans. Review your storm water pollution prevention plan, train your personnel, clean up outdoor exposed materials, perform good housekeeping practices to reduce and prevent pollution, and organize sample kits for those who will conduct sampling. Now is the time to inspect your site for potential flood impacts, erosion control issues, and to perform drainage system cleaning and maintenance. With all the recent fires in California, burn sites will have a higher risk for sediment and debris flows, as we saw in previous years with devasting mudflow events. It is important to have plans for early warning systems and ensure that your business has procedures for evacuation and contingency planning for flood events, if you are in one of these areas.
NV5 is a Weather-Ready Nation Ambassador (WRN) with the NOAA. As a WRN Ambassador, NV5 supports NOAA’s initiatives to inspire others to be better informed and prepared, helping to minimize or avoid the impacts of natural disasters by educating employees and the business community on workplace preparedness. More information about WRN and weather preparedness can be found at https://www.weather.gov/wrn/.