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California: Waiting for El Nino
The title should read ’Waiting for El Nino-enhanced precipitation’ to affect the state since this, so far, has yet to occur. However, hopefully this will be the last blog I write for a while concerning how dry California has been these past years: a series of storms are now taking aim at the state and, perhaps, the beginning to the end of California’s drought nightmare is at hand. Nevertheless, there is an item of concern: previous strong/very strong El Ninos brought heavy early season rain and snow to the state during their respective Novembers. This has not happened this time around. Here are the details.
As we approach mid-December it is finally appearing that the much anticipated heavy rain and snowfalls that normally affect California during strong/very strong El Ninos are beginning to take shape. Until now the jet stream has been funneling storm after storm into the Pacific Northwest (where flooding is now happening but, so far, only relatively light rain/snow has fallen in California (for the most part).
Although it is said that the ‘real’ affects of strong El Ninos (precipitation-wise) normally do not begin in California until January this is not true. In fact, if we look at the historical record, November also usually sees much above normal precipitation in California during strong/very strong El Nino events whereas Seattle (as an example for the Pacific Northwest) sees below average precipitation. The reverse occurred this year. Let’s take a look at the past six times since 1950 that a strong/very strong El Nino developed and how much actual precipitation was measured during the Novembers of those years in Seattle, San Francisco, and Los Angeles.
The graph above shows the Oceanic Nino Index since 1950. The winter seasons that experienced strong/very strong El Ninos were those of 1957-1958, 1965-1966, 1972-1973, 1982-1983, 1997-1998, and, of course, this season of 2015-2016. Graph by Jan Null of Golden Gate Weather Services using data from NOAA/CPC.
Now let’s look at how much rain fell during the Novembers of those years in Seattle, San Francisco, and Los Angeles (and what the 30-year November precipitation normals are).
As we can see, this past November was an anomaly with much below average precipitation in SF and LA and much above average in Seattle. No previous strong/very strong El Nino (since 1950 at least) has seen this happen (except for November 1957 in the Los Angeles case). Obviously, this time around the El Nino seasonal precipitation pattern has not commenced in a similar way (as in former El Ninos). Does this mean that this season’s El Nino (currently on track as one of the strongest on record) will be a bust for California? I doubt this and remain optimistic that the state will see exceptionally heavy precipitation as the coming weeks and months progress. The slow start is most likely a result of other factors not directly related to El Nino. I hope.
Where California Stands Precipitation-wise as of December 9th
As of the time I write this, the precipitation season (which begins on July 1st) and the calendar year-to-date precipitation has been exceptionally deficient almost statewide. Snow/water content is around 60% of normal for this time of the season in the Sierra Nevada and the state’s reservoirs are at just 51.5% of normal capacity for the time of year.
Snow/water content in the Sierra Nevada (top map) and reservoir capacity for the state as of December 8th. Both graphics courtesy of the California Department of Water Resources.
In so far as individual cities are concerned, it remains the driest calendar year on record for San Francisco, Redding, and Blue Canyon (located in the central Sierra at around 5,000’ elevation). Only southern California has seen above normal or close to normal precipitation, this a result of some unusually heavy rains in the July-September period when dissipating tropical storms and a very active monsoonal season affected much of the Southwest. San Francisco’s paltry 4.78” since January 1st (as of December 9th) is especially remarkable since it was just two years ago that the previous driest year on record occurred with a 5.59” total in 2013. San Francisco’s precipitation period of record (POR) dates back to 1849 and is one of the longest such for any city in the U.S. That being said, it is almost certain an additional .81” will fall by the end of the month if not in the next few days. Nevertheless, this year does have a shot at of becoming the 2nd driest year on record. That feat is currently held by 1917 when 9.00” was measured.
Precipitation for select Californian cities/towns so far this season (since July 1st) top table and so far this calendar year (bottom table) as of December 9th.
I suspect the figures in the above tables will look quite different by the end of this month!
For a deeper analysis of the California weather/climate situation you can do no better than to follow The California Weather Blog by Daniel Swain.
Christopher C. Burt
Weather Historian
The title should read ’Waiting for El Nino-enhanced precipitation’ to affect the state since this, so far, has yet to occur. However, hopefully this will be the last blog I write for a while concerning how dry California has been these past years: a series of storms are now taking aim at the state and, perhaps, the beginning to the end of California’s drought nightmare is at hand. Nevertheless, there is an item of concern: previous strong/very strong El Ninos brought heavy early season rain and snow to the state during their respective Novembers. This has not happened this time around. Here are the details.
As we approach mid-December it is finally appearing that the much anticipated heavy rain and snowfalls that normally affect California during strong/very strong El Ninos are beginning to take shape. Until now the jet stream has been funneling storm after storm into the Pacific Northwest (where flooding is now happening but, so far, only relatively light rain/snow has fallen in California (for the most part).
Although it is said that the ‘real’ affects of strong El Ninos (precipitation-wise) normally do not begin in California until January this is not true. In fact, if we look at the historical record, November also usually sees much above normal precipitation in California during strong/very strong El Nino events whereas Seattle (as an example for the Pacific Northwest) sees below average precipitation. The reverse occurred this year. Let’s take a look at the past six times since 1950 that a strong/very strong El Nino developed and how much actual precipitation was measured during the Novembers of those years in Seattle, San Francisco, and Los Angeles.
The graph above shows the Oceanic Nino Index since 1950. The winter seasons that experienced strong/very strong El Ninos were those of 1957-1958, 1965-1966, 1972-1973, 1982-1983, 1997-1998, and, of course, this season of 2015-2016. Graph by Jan Null of Golden Gate Weather Services using data from NOAA/CPC.
Now let’s look at how much rain fell during the Novembers of those years in Seattle, San Francisco, and Los Angeles (and what the 30-year November precipitation normals are).
As we can see, this past November was an anomaly with much below average precipitation in SF and LA and much above average in Seattle. No previous strong/very strong El Nino (since 1950 at least) has seen this happen (except for November 1957 in the Los Angeles case). Obviously, this time around the El Nino seasonal precipitation pattern has not commenced in a similar way (as in former El Ninos). Does this mean that this season’s El Nino (currently on track as one of the strongest on record) will be a bust for California? I doubt this and remain optimistic that the state will see exceptionally heavy precipitation as the coming weeks and months progress. The slow start is most likely a result of other factors not directly related to El Nino. I hope.
Where California Stands Precipitation-wise as of December 9th
As of the time I write this, the precipitation season (which begins on July 1st) and the calendar year-to-date precipitation has been exceptionally deficient almost statewide. Snow/water content is around 60% of normal for this time of the season in the Sierra Nevada and the state’s reservoirs are at just 51.5% of normal capacity for the time of year.
Snow/water content in the Sierra Nevada (top map) and reservoir capacity for the state as of December 8th. Both graphics courtesy of the California Department of Water Resources.
In so far as individual cities are concerned, it remains the driest calendar year on record for San Francisco, Redding, and Blue Canyon (located in the central Sierra at around 5,000’ elevation). Only southern California has seen above normal or close to normal precipitation, this a result of some unusually heavy rains in the July-September period when dissipating tropical storms and a very active monsoonal season affected much of the Southwest. San Francisco’s paltry 4.78” since January 1st (as of December 9th) is especially remarkable since it was just two years ago that the previous driest year on record occurred with a 5.59” total in 2013. San Francisco’s precipitation period of record (POR) dates back to 1849 and is one of the longest such for any city in the U.S. That being said, it is almost certain an additional .81” will fall by the end of the month if not in the next few days. Nevertheless, this year does have a shot at of becoming the 2nd driest year on record. That feat is currently held by 1917 when 9.00” was measured.
Precipitation for select Californian cities/towns so far this season (since July 1st) top table and so far this calendar year (bottom table) as of December 9th.
I suspect the figures in the above tables will look quite different by the end of this month!
For a deeper analysis of the California weather/climate situation you can do no better than to follow The California Weather Blog by Daniel Swain.
Christopher C. Burt
Weather Historian
Extreme Weather El Nino Precipitation Records
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.