Brazil’s farms in the south are fighting a drought, Kenya and Tanzania are wetter than normal while Madagascar is in a deep dry. Northern Europe is very wet while Spain is drier than normal. Central SE USA just saw deadly tornadoes and is much wetter than normal – and California is experiencing an absolute record dry. California’s extreme weather is once again in the news as the state just recorded the driest February on record.
February is normally one of the wettest months, yet Sacramento, for the first time ever (since 1864), saw zero precipitation for the 29 days of February. The two maps below show this pattern across California and Nevada. The fire risk in these already fire-prone regions will likely be extremely high in 2020.
A closer look into California and Nevada and we see the extent of the dry – some areas received 0 rainfall in February 2020 with nearly all of California receiving less than 10 mm.
As we look into the current situation in California, we can see that precipitation has been abnormally low since October 2019 with a few exceptions in December 2019. January 2020 was also abnormally drier than normal (based on 2006-2019), shown in the map below.
The map to the left represents the variability during the 3-month period (Dec-Feb). The coefficient of variation (CV) is shown with higher percentages reflecting greater variability. For California, this indicator is high (> 30%) across the state except for the NW corner.
Precipitation variability, especially in the mountains of eastern California, is of great concern as this snowpack is vital to recharge water ways for forests and irrigation.
Further, we can examine the last 14 years and see trends across that state that are disturbing: winter is becoming drier especially in southern California and along the eastern border of the mountains. This can lead to potentially catastrophic fires in the dry season (May-September). Stream-flow will be lower that will impact fisheries and reduce access to water for irrigating California’s valuable crops.
Implications and Recommendations
With timely insights are critical for governments, emergency response, homeowners and farmers to take appropriate action to reduce risks associated with weather variability in California. Weather insights can guide infrastructure investments (such as watershed/irrigation management) to reduce the impact of rainfall variability and reduce the incidence and impact of fires.