Climate Literacy

Session: Climate, Climatology of California

Elissa LynnAugust 5, 2015

Climate, Climatology of California

• California Climate

• Climate Signals

• Atmospheric Rivers

California Geography (Major Climate Factor)

• 1340 miles of coastline

(~75% coast of lower US)

• 800 miles long

• 250 miles wide

• LA is east of Reno

• Land area of 163,696 sq. miles

3.79 million sq. miles –

3rd biggest after AK and TX

California Geography (Major Climate Factor)

• 1340 miles of coastline

(~75% coast of lower US)

• 800 miles long

• 250 miles wide

• LA is east of Reno

• Land area of 163,696 sq. miles

3.79 million sq. miles –

3rd biggest after AK and TX

Mediterranean Climate - warm dry summer, cool wet winter

California Topography (Major Climate Factor)

Greatest Precipitation falls in northern mountains in CA

Biggest Population centers are along coasts and southern part of CA

Precipitation: Limited Locations

Dettinger et al, 2011

Just a few storms each year provideCalifornia’s water supply

5-10 stormy days or storm events each winter

December, January, February responsible for 50% of precipitation

Precipitation: Limited Opportunity

Dettinger et al, 2011

Measuring CA Precipitation

Northern Sierra 8 Station Index

Annual Average: 50 inchesMaximum Year (1983): 88.5 inchesMinimum Year (1924): 17.1 inchesPeriod of Record 1921- Present

Average of:

Mt. Shasta City QuincyShasta Dam Sierraville RSMineral Pacific HouseBrush Creek RS Blue Canyon

1921

1922

1923

1924

1925

1926

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2012

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2014

0

20

40

60

80

100

Water Year

Pre

cip

ita

tio

n (

Inc

he

s)

1949

1950

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2014

0102030405060708090

Water Year

Pre

cip

ita

tio

n (

Inc

he

s)

Annual Average: 40 inchesMaximum Year (1983) 77.4 inchesMinimum Year (1924) 14.8 inchesPeriod of Record 1949 - Present

Average of:

Calaveras Big TreesHetch HetchyYosemite HQNorth Fork Ranger StationHuntington Lake

Measuring CA Precipitation

Southern Sierra 5 Station Index

Snowpack

Drought

Worst Years for SnowpackApril 1 Percent of Average

2015 5

2014             25

1977             25

1988            29

1976            37

2007            39

2013            42

1963            45

1990             45

1994             52

2012             52

Each of last 4 years are in the top-10 lowest snowpacks5 of 10 driest years in last hundred have been this decade

1977 used to be worst; 2014 tied at 25% of average2015 was 20% of EITHER of those; only 5% of average

System managed better than in 1977; but worse hydrologyIn recent years, it’s WARMER

Drought

Runoff Observations: Timing Shift

Brochure Page 3

California 1895-PresentCourtesy: Western Region Climate

Center

Observed Maximums

Observed Minimums

Temperatures

Climate Signal; El

Nino

El Niño conditions are present

Warm Sea Surface Temperatures over Eastern Pacific (us!)

Greater than 90% chance that El Niño will continue through winter, and around an 80% chance it will last into early spring 2016.

Climate Signal; El

Nino

Climate Signal; Pacific Decadal Oscillation

Storm Track changes

Flooding & water supply

MJO/Tropical Convection ENSO

Polar Processes

Atmospheric

River

Easterly Wave

Cyclogensis

L

Different Hydrologic Outcomes Result from the Combination of Key Processes Evolving at

Different Space/Time Scales

Climate Signal; Atmospheric Rivers -> KEY for Water Supply/Flooding

https://www.youtube.com/watch?v=MgKT__9ThSs&feature=youtu.be

Atmospheric Rivers (CalWater Research) DWR YouTube

Take Home PointsCalifornia has a Mediterranean Climate

Topography/Geography very important for CA precipitation

Lots of variability in space and time

Many processes in play to create events in historic record

Atmospheric Rivers important for floods and water supply

Climate Change will impact these relationships; drought, etc.