GrokSurf's San Diego

Local observations on water, environment, technology, law & politics

Winter precipitation outlook for San Diego and California

Posted by George J Janczyn on November 3, 2009

I attended a California Department of Water Resources workshop in downtown San Diego this morning to hear a report on the outlook for water supply conditions for the 2010 rainy season. I’m sure there will be more detailed reports by media water analysts by tomorrow, but here are a few highlights:

  • Latest data on El Nino show it may be dramatically strengthening. If the new trend continues, it could translate into wetter weather for San Diego
  • The big October rain event was not related to El Nino, but rather was due to a moisture plume (“river”) that was injected into the atmosphere by a typhoon in the western Pacific and carried towards California via jet stream and pressure systems (a “pineapple express” effect)
  • The October rain event has probably recharged ground moisture enough that if we get good precipitation from here on, it won’t be absorbed as much and stream runoff will be much better, which translates into more water for reservoirs.
  • Winter snow is preferable to spring rains as snow provides more predictable stream runoff in the spring which can be more readily managed
  • Unusually cold weather recently in the midwest does not support a conclusion that climate warming is not occurring
  • Preparations must continue for protecting areas damaged by wildfires with increased possibility of flash flooding and debris flows
  • Looking at the long historical record, effects from El Ninos are becoming less predictable
  • It is becoming more popular in the media to blame precipitation events (or non-events) on climate change rather than El Nino (brings this caution to mind)
  • Overall consensus: guarded optimism that we’ll have reasonably good precipitation over the coming rainy season


[Nov 4: updated with breaking news reports]


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