The Department of Water Resources’ new California Water Watch website is a great new resource, however, the site appears to miss information on the rapidly developing drought.
The website displays statewide precipitation for the water year to date. It also displays a map of “Drought Risk Impacts” based on precipitation being less than 70% of average for the water year to date, and temperatures being greater than the 80th percentile. The map for February 20, 2022 is shown below:
Intuitively, the map appears to underestimate developing drought risk in the state. Climate scientist Daniel Swain explains why in a February 17, 2022 Twitter thread:
October and December were extremely wet in parts of California (record wet in some parts of NorCal). But the most recent ~45 day stretch (Jan 1-Feb 17) has been among driest mid-winter periods on record most of CA, NV, UT, and portions of adjacent states. #CAwx #CAwater (1/3) pic.twitter.com/qS3rrQJmUV
— Daniel Swain (@Weather_West) February 17, 2022
Yet hydrologic/landscape conditions–inc. surface reservoirs, soil moisture, streamflow, & vegetation aridity–are at extremely dry levels for mid-winter. This is due to 1) ongoing long-term drought and 2) the recent 6+ week record dry/warm & windy spell. #CAwx #CAWater (3/3) pic.twitter.com/c3KLkKFwDr
— Daniel Swain (@Weather_West) February 17, 2022
Given the kind of water whiplash we have seen this year, it seems essential to look at shorter time frames in evaluating drought risk. Yet the February 4, 2022 California Hydrology Update by DWR’s state climatologist, Michael Anderson, only states,
To date statewide for the current water year (October 1, 2021- September 30, 2022), precipitation is 104% of average, down significantly from the end of December when it was near 150% of average.
If California is going to manage for drought risk, we need to step up our game.
