4 ms·

I think there is some selection bias in maps like this because it has no data on above average rainfall. I know where I live we've had one of the rainiest summe

I think there is some selection bias in maps like this because it has no data on above average rainfall. I know where I live we've had one of the rainiest summers ever but you won't see this on a map like this.

joe_the_user 4y ago
The monitor seems problematic to me in all sorts of ways. As you say, there's no reference to above average rainfall. Also, it should be base-lining on the median result, not the average result. California has always had a few very wet and many dry years so the monitor usually shows drought. This serves developers and farmers who don't want to admit California is dry place and you should do projects taking a lot of water. And finally, the drought monitor measures dryness, not overall rainfall but it doesn't make this obvious. California's reservoirs are low but we have had fairly typical (median) rainfall for the last two years (and even had an usually humid spring and summer). The difference is increased heat increases evaporation and dryness and the map should make this distinction obvious.
- richiebful1 4y ago
  It's better to go to the government agency site for the source data. They make it clear that the drought level is based on the availability of water compared to normal. https://www.drought.gov/data-maps-tools/us-drought-monitor https://www.drought.gov/data-maps-tools/us-drought-monitor
  - UncleEntity 4y ago
    And the map isn’t generated for people to whine about growing alfalfa in California but to determine crop insurance rates &etc…
simonsarris 4y ago
Drought.gov actually keeps track of that! For example for New Hampshire: https://www.drought.gov/states/new-hampshire https://www.drought.gov/states/new-hampshire Scroll down to the graph, click "1895 - Present (Monthly)", and click the different levels of exceptional drought/exceptional wetness. You can see that NH has been trending wetter for the last 100 years (as with all the northeast), more or less the opposite of the southwestern US. Large periods of exceptional wet have happened in my life, with fewer big droughts than ever. (Alas, we're in a drought right now.) You can also see that California had some unusually wet periods in the 80's and 90's, which might have informed policy, but were simply an anomaly: https://www.drought.gov/states/california https://www.drought.gov/states/california

joe_the_user 4y ago

The monitor seems problematic to me in all sorts of ways. As you say, there's no reference to above average rainfall. Also, it should be base-lining on the median result, not the average result. California has always had a few very wet and many dry years so the monitor usually shows drought. This serves developers and farmers who don't want to admit California is dry place and you should do projects taking a lot of water. And finally, the drought monitor measures dryness, not overall rainfall but it doesn't make this obvious. California's reservoirs are low but we have had fairly typical (median) rainfall for the last two years (and even had an usually humid spring and summer). The difference is increased heat increases evaporation and dryness and the map should make this distinction obvious.

richiebful1 4y ago
It's better to go to the government agency site for the source data. They make it clear that the drought level is based on the availability of water compared to normal. https://www.drought.gov/data-maps-tools/us-drought-monitor https://www.drought.gov/data-maps-tools/us-drought-monitor
- UncleEntity 4y ago
  And the map isn’t generated for people to whine about growing alfalfa in California but to determine crop insurance rates &etc…

simonsarris 4y ago

Drought.gov actually keeps track of that! For example for New Hampshire: https://www.drought.gov/states/new-hampshire https://www.drought.gov/states/new-hampshire Scroll down to the graph, click "1895 - Present (Monthly)", and click the different levels of exceptional drought/exceptional wetness. You can see that NH has been trending wetter for the last 100 years (as with all the northeast), more or less the opposite of the southwestern US. Large periods of exceptional wet have happened in my life, with fewer big droughts than ever. (Alas, we're in a drought right now.) You can also see that California had some unusually wet periods in the 80's and 90's, which might have informed policy, but were simply an anomaly: https://www.drought.gov/states/california https://www.drought.gov/states/california