BULLETIN 120: April 12, 2022

From the Department of Water Resources:

The Department of Water Resources has finished the April 12, 2022 Bulletin 120 (B120) forecast update. The forecast includes observed conditions through the morning of Tuesday, April 12, 2022.

 The forecasts are posted at:

B120 Update:   https://cdec.water.ca.gov/reportapp/javareports?name=B120UP

B120 Update WY Distribution:  https://cdec.water.ca.gov/reportapp/javareports?name=B120DIST

Forecast Summary:

The projected median April-July (AJ) runoff ranges in the major Southern Cascades/Sacramento River basins from 21 percent of average for the Trinity River basin to 53 percent of average for the Pit River basin, in the major San Joaquin River basins from 24 percent of average for the Cosumnes River basin to 50 percent of average for the San Joaquin River basin, and in the major Tulare basins from 19 percent of average for the Tule River basin to 43 percent of average for the Kings River basin.

Since the April 1 B120 was issued, the AJ forecasts for most river basins have decreased between 1 and 5 percent of average due to below median precipitation in the first third of April. The Feather River basin forecast was the only to increase, rising 2 percent of average due to higher than expected flows since April 1. Forecasts in the McCloud, Pit, and American River basins remain unchanged since the April 1 B120.

Runoff:

Since April 1, daily full natural flow rates have mostly fluctuated up and down during the first week and then declined during the second week due to overcast skies and decreasing temperatures.  The Trinity and Sacramento River have shown response to the recent rainfall, increasing over the past few days.  The Trinity and Sacramento Region rivers are running below half of their respective April average flow rate, except for the American River which is running at 56 percent of average. All rivers in the San Joaquin and Tulare Lake basins are flowing above 60 percent of average, except for the Cosumnes, Tule, and Kern rivers which are flowing decidedly lower. The Trinity, Sacramento, Cosumnes and Tule rivers are flowing at a rate equal to or less than 30 percent of average for the month.

Unimpaired flows in Percent of Average for Water Year 2022 are as follows:

River

Oct

Nov

Dec

Jan

Feb

Mar

Oct-Mar

Apr (Month to Date)

Trinity

312

195

40

46

32

28

49

24

Shasta

104

104

72

67

29

25

53

30

Sacramento at Bend Bridge

125

115

76

54

25

23

51

30

Feather

348

137

117

74

45

47

79

42

Yuba

566

163

117

58

35

42

74

49

American

814

198

144

58

40

48

80

56

Sacramento Region

233

131

99

60

33

35

64

 

Cosumnes

1334

151

254

51

28

22

66

22

Mokelumne

732

234

135

58

49

58

87

74

Stanislaus

432

161

146

47

47

56

77

63

Tuolumne

384

176

143

45

39

49

74

73

Merced

277

167

140

42

36

51

65

83

San Joaquin

282

170

215

71

67

73

102

86

San Joaquin Region

402

176

165

52

45

53

79

 

Kings

96

100

126

54

49

59

68

73

Kaweah

70

49

99

38

34

42

47

61

Tule

65

29

95

35

22

26

36

29

Kern

51

58

72

45

37

34

45

40

Tulare Region

76

74

104

48

41

47

56

 

Precipitation:

As of the morning of April 14th, despite recent precipitation events, all three precipitation indices have accrued precipitation at a rate well below average for the month of April. However, significant precipitation forecast over the next week has the potential to finally end the three-month streak of well below average precipitation in the Northern and Central Sierra.

Precipitation summary for Water Year 2022 as of April 14, 2022:

Region

Percent of Average

Precipitation (inches)

Oct

Nov

Dec

Jan

Feb

Mar

Apr (Month to Date)

WY to Date

Apr (Month to Date)

WY to Date

Northern Sierra 8-Station Index

453

58

144

14

4

16

16

73

0.7

33.9

San Joaquin
5-Station Index

314

25

195

0

2

26

14

65

0.5

22.6

Tulare Basin
6-Station Index

216

7

221

0

9

31

4

60

0.1

15.0

Snowpack:

The statewide snow water equivalent (SWE) based on snow sensors is 6.6 inches which corresponds to 25 percent of normal for this date and 24 percent of the April 1 average.  Since April 1, the statewide snowpack has decreased by 3.7 inches. Snowmelt was high at the start of the month with increased temperatures and solar radiation but recent precipitation has added back to the snowpack over the last three days.

The regional snowpack levels as of the morning of April 14, 2022 stand at the following (based on snow sensors): 

Region

No. of Stations

Avg. SWC

Percent of April 1

Percent of Normal

Northern

29

5.0

18

20

Central

44

8.2

27

28

Southern

25

5.9

24

25

Statewide

98

6.6

24

25

Weather and Climate Outlooks:

According to CNRFC 6-day forecast, significant precipitation is forecasted across the Northern two thirds of the state. The present front is expected to continue to move across the state before clearing on Sunday with another storm following behind it. The highest totals of precipitation are forecasted for the Northern Sierras and North Coastal range with potential totals in excess of 5 inches in some places. The Central Coast and Central Valley are forecast to receive up to an inch of precipitation with levels declining farther south. Freezing levels are currently at 4,000-6,000 feet in the northern basins and 6,000-7,000 feet in the southern Sierras. For the northern basins, the freezing level will increase to 7,000-8,000 feet by Sunday and then begin to decline starting Monday. The freezing elevation will increase to 9,000-11,000 by Sunday for the southern Sierras for the rest of the forecast window. Southern California freezing levels are currently 10,000-12,000 feet and will slowly rise across the forecast window.   

The NWS Climate Prediction Center (CPC) one‐month outlook issued on March 31, 2022, suggests equal chances of above or below normal temperatures throughout the northern quarter of the state; it suggests above average chances for higher-than-normal temperatures in the remainder of the state. The same forecast suggests the entire state has slightly increased chances for below normal precipitation for April.

The CPC three-month (April-May-June) outlook, issued on March 17, 2022, suggests equal chances of above or below normal temperatures for the central coast and northern third of the state; for the rest of the state increased chances of above average temperatures are expected.  The outlook also shows equal chances of above or below normal precipitation for the southern half of the state and increased chances of below normal precipitation for the northern half.

According to the latest El Niño/Southern Oscillation (ENSO) discussion issued by the CPC on April 11, 2022, La Niña conditions are present. Equatorial sea surface temperatures (SSTs) are below average across the east-central and eastern Pacific Ocean. The tropical Pacific atmosphere is consistent with La Niña.  These conditions are favored to continue into the Northern Hemisphere summer (53 percent chance during June-August 2022), with a 40-50 percent chance of La Niña or ENSO-neutral thereafter.

Next Update:

A Bulletin 120 update forecast for conditions as of April 19, 2022, will be available on Thursday, April 21st.  If you have any questions regarding this forecast, please contact a member of the Snow Surveys and Water Supply Forecasting staff.

Important Links: 

Full Natural Flow Data:  

Precipitation Data:  

Snow Data: 

Extended Regional Forecasts:  

Bulletin 120: 

Other Useful Links:

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