An Overview of New Tools to Help Forecast Unusual to Extreme Weather Events in Southern California

On 30 April, 2014 high winds developed in San Diego County. Sill Hill, which appears to be the windiest location in San Diego County, recorded a wind gust of 101 mph. On 26 February, 2020, that mark was surpassed with a value of 106 mph, possibly the highest wind gust ever measured in San Diego County. Both events occurred under Santa Ana Wind conditions.

The models are improving steadily and can now get an overall feel of the winds and wind patterns in southern California, but still struggle with extreme events and the locations of such events. Therefore an adjustment on the guidance is needed for these events. An “Adjusted Multiple Regression” approach was utilized to help determine approximated wind gust speeds for locations that experience extreme values such as Sill Hill.

This is critical, since under such extreme wind conditions at Sill Hill, wind gusts that are somewhat weaker, but still damaging, reach other sites as well, and it becomes nearly impossible to battle the prevalence of damaged transmission lines and/or wildfires, thus accurate forecasts become optimally important to the delivery of precise IDSS messaging for such problems.

Also there are new tools available for looking at upcoming conditions both in the short and long range to assist in the forecasting of extreme events and should result in improved IDSS messaging. It has been found that combined with the “Adjusted Multiple Regression” approach based on selected parameters, (especially utilizing the tools and trusted parameters of skilled forecasters), the quality and utility of IDSS messaging can be increased, (not just for wind, but for temperature forecasting and damaging rainfall/flooding events as well). Some thoughts on how the National Blend of Models (NBM) and probabilistic data plays into this are also discussed from a point approach as well as an “area “approach.