This winter for California was chugging along to be one of the driest in recent years. The snowpack in the Sierra by early March was puny compared to normal, and rainfall was up to 70% lower than normal in many places in the state. This was at least partially due to a pretty decent La Nina for much of the time from November through February. However, the La Nina was weakening and that continued over the following weeks. This, at least in part, may have helped along the rather stormy weather pattern of the last month. While precipitation levels, and most importantly the snowpack, have not recovered to normal in many areas (there is an exception) the current water situation is far better than it was just a little over a month ago.
To show this I have a few charts for you. The first shows precipitation amounts accumulated over two separate time periods for select cities from north to south. The first time block is from Nov. 1 through March 14, the second is from March 15 through midnight last night. In each column is the amount of rain that has fallen and in parenthesis the percentage of normal for the time period listed.
It is easy to see two things. The first is how wet the last month has been and the second is how dry the previous four and a half months were. Also note that a few cities had nearly as much, or more, rain in the past month than they did in the previous four and a half months.
The next two charts show the snow water equivalent in the snowpack in the Sierra. The first was on March 14 and the second was this morning.
There was considerable recovery here too, especially in the northern and central Sierra with the northern Sierra getting back to what is normal. The average statewide has more than
doubled in the last month.
A prolonged rain-free pattern is setting in.
By this time in 1998 there was twice as much rain that had occurred to date compared to 2015-2016.
Could an unusual El Nino precipitation pattern be as simple as looking at the state of water temperatures?
One thing that I find interesting is that the pattern since fall has not been your typical El Nino storm pattern.
There are signs of a possible stormier pattern beginning the week of Jan. 18.
The cumulative effect of the series of storms will mean flooding, mudslides and debris flows are going to be a problems for much of the week