California Rainfall and Reservoir Update

 

2018-2019 CALIFORNIA WATER BY THE NUMBERS

It's should be no surprise that abundant rainfall this season has translated into a pretty bright picture for water supplies across the Golden State. 

The latest Drought Monitor shows California with its least amount of drought-impacted area since 2011. With only 0.60% in the Moderate Drought category (D1) and 9.56% in D0 (Abnormally Dry), California is at its most drought free since 8-30-2011. 

 The latest California Precipitation Snapshot shows rainfall already approaching or above normals for the entire is rainfall season (July 1 to June 30).

Of particular note is the 8-Station Northern Sierra Index, with state's largest reservoirs, which is now at 128% of normal and just 2.33" shy of their seasonal normal of 54.52".

  
And all of the above translates into California reservoir levels close to or exceeding historical averages for this time of year. 


Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

 

Posted

February 5th Bay Area Snow; But Not like 1887 or 1976


Historically, February 5th is the snowiest day of the year in San Francisco and the Bay Area. Of the 11 days when snow has been recorded near sea level in San Francisco, twice before on February 5th. In 1887 and again in 1976. (https://www.ggweather.com/sf/snow.htm)


The event on February 5, 1887, was the snowiest on record with over 3 inches in the downtown area of the City.  This is well documented in Mark McLaughlin's wonderful  "San Francisco Snowstorms" document (http://thestormking.com/Sierra_Stories/San_Francisco_Snowstorms/san_francisco_snowstorms.html)


And the last time there was an accumulation of snow near sea level in San Francisco was on February 5, 1976, with up to an inch downtown and 5" on Twin Peaks. (Spectacular photograph below: Art Frisch, SF Chronicle), 



The forecast conditions for tomorrow, February 5, 2019, do NOT look like a repeat of either one of the previous snow events. But the combination of much colder air moving into the region and continued bands of showers overnight should at least whiten the hills above 2000' and in some areas, especially inland possibly down to into the 1000' to 1500' range.

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather


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Significant Rainfall Gains Statewide


The first 16 days of January have seen great rainfall recoveries across California from recent storms. Most locales have jumped by about 20% versus their Jan. 1st %-of-normal numbers. The very important 8-Station N Sierra Index (8SI) has jumped to 89% of normal while both Redding and Sacramento are now just above normal. For others see below or https://www.ggweather.com/water/.

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather



 

 

Posted

California Rainfall Update and Odds


 

With no rain in the forecast through the end of the year, here are some updates on where California stands precipitation-wise. Most of the state north of the Tehachapis is about 75% of normal, while to the south it is averaging from near to slightly above normal.

Through Dec 31, San Francisco will be at 5.95 inches or 65% of normal. This is the 63rd driest out of the 170 seasons dating back to 1849. Looking at the 30 seasons that had this value plus/minus an inch, the corresponding end of the rainfall season (Jul 1 through Jun 30) totals ranged from 11.06" to 27.86". This breaks down further with 6 seasons at < 60% of normal, 11 seasons at 61-80% of normal, 8 seasons at 81-100% and 5 seasons in the 100 to 120 percent of normal. 

https://www.ggweather.com/water/
 





Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather

 

Posted

Significant Rainfall Gains

Last week's rains made a significant dent in California rainfall deficits, pushing many northern California areas from around 10% of their normal late November rainfall to over 50% of normal. And forecast charts continue to show at least moderate rain at times this week in the Tuesday through Thursday timeframe. See https://www.ggweather.com/seasonal_rain.htm and https://www.ggweather.com/water/









 

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com  
Web: http://ggweather.com
Twitter: https://twitter.com/ggweather
Facebook: https://www.facebook.com/Golden-Gate-Weather-Services-151100414926621/

 

Posted

A dry start to the SF rainfall season; What does it mean?

 

So far, the 2018-2019 rainfall season has been pretty dry, with only 0.21” having fallen in downtown San Francisco. But it is far from the driest, with 26, out of 169 previous July 1st to October 31st totals having lesser amounts.

Looking at the 47 seasons that ranged from 0.00” to 0.42” for teh first 4 months of the rainfall season:
25 (53%) ended with less than 80% of normal by June 30th,
15 (32%) ended with between 80% and 120% of normal, and
7 (15%) of the seasons finished with more than 120% of normal.

It is interesting to note that both San Francisco’s all-time driest and wettest seasons began dry. The driest was 1850-1851 with a July to October total of 0.33” and a final seasonal total of just 7.42”. Conversely, 1861-1862, after having only 0.02” through October, finished with a fantastic (except for the flooding) record season of 49.27”.

List of the 48 driest beginnings to the SF rainfall season:

 

 

 

End of Season

Rank

Season

Jul-Oct

Total

% Normal

1

1855-1856

0.00

21.66

92%

2

1905-1906

0.00

20.42

86%

3

1929-1930

0.01

16.28

69%

4

1932-1933

0.01

14.93

63%

5

1861-1862

0.02

49.27

208%

6

1915-1916

0.02

27.12

115%

7

1917-1918

0.02

11.48

49%

8

1863-1864

0.03

10.08

43%

9

1870-1871

0.03

14.11

60%

10

1880-1881

0.05

29.86

126%

11

2002-2003

0.05

23.87

101%

12

1995-1996

0.06

24.89

105%

13

1928-1929

0.07

15.21

64%

14

1955-1956

0.07

27.17

115%

15

1952-1953

0.08

21.10

89%

16

1871-1872

0.09

30.78

130%

17

1859-1860

0.10

22.27

94%

18

2003-2004

0.10

20.54

87%

19

1866-1867

0.11

34.92

148%

20

1980-1981

0.11

14.63

62%

21

1868-1869

0.15

21.35

90%

22

1872-1873

0.16

15.66

66%

23

1903-1904

0.17

20.59

87%

24

1949-1950

0.18

16.78

71%

25

1978-1979

0.19

18.70

79%

26

2015-2016

0.20

23.26

98%

27

2018-2019

0.21

??

??

28

1958-1959

0.21

10.46

44%

29

1875-1876

0.24

31.19

132%

30

1867-1868

0.24

38.84

164%

31

1946-1947

0.27

14.89

63%

32

1966-1967

0.27

29.41

124%

33

1911-1912

0.28

14.06

59%

34

1887-1888

0.30

16.74

71%

35

1914-1915

0.31

27.41

116%

36

1961-1962

0.33

17.65

75%

37

1850-1851

0.33

7.42

31%

38

1890-1891

0.33

17.58

74%

39

1948-1949

0.33

18.28

77%

40

1993-1994

0.33

15.22

64%

41

1864-1865

0.35

24.73

105%

42

1971-1972

0.35

11.06

47%

43

1990-1991

0.36

14.08

60%

44

2008-2009

0.36

18.11

77%

45

1893-1894

0.39

18.47

78%

46

1906-1907

0.40

26.17

111%

47

1953-1954

0.41

14.27

60%

48

2017-2018

0.42

17.53

74%

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Twitter: @ggweather
 

Posted

CPC Winter Outlooks and an Updated El Niño Forecast

 

 

With the latest NOAA 2018-2019 Winter Outlook just released, here's how the previous three CPC Winter Precipitation Outlooks "verified". At least here on the West Coast they seem to have pretty much missed the mark.



And the just updated IRI/CPC Oceanic Niño Index (ONI) forecast is significantly warmer than last month's; pushing the winter months into the moderate El Niño category.

However, even in the moderate El Niño category there is still a large range of solutions and little predictive value. See https://www.ggweather.com/ca_enso/ca_elnino.html for the California and https://www.ggweather.com/enso2016/us_elnino.html for the US.



Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Web: http://ggweather.com
Twitter: @ggweather
 

 

Posted

New & Improved El Niño (and La Niña) California Precipitation Climatology


The Climate Prediction Center (CPC) currently has an El Niño Watch for this coming Fall and Winter, though they have been gradually decreasing its probability of occurrence in recent months.


I have put together a new & improved comprehensive California Precipitation climatology for ENSO (i.e., El Niño and La Niña) events. See 
https://www.ggweather.com/ca_enso/ca_elnino.html and https://www.ggweather.com/ca_enso/ca_lanina.html.



The climatology is based upon the 10 California Hydrologic regions (map) and generated with the updated (and excellent) Western Region Climate Center's California Climate Tracker tools.

As always, corrections, comments and corrections are greatly appreciated.

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com
Web: http://ggweather.com
Facebook: Golden-Gate-Weather-Services
Twitter: @ggweather

 

Posted

PG&E and SoCal Edison Mesonets

In recent months both Pacific Gas & Electric (PG&E) and Southern California Edison (SCE) have been installing extensive weather station networks. Primarily mounted on utility poles they gather wind, temperature and humidity data every 10 minutes. Currently PG&E has about 100 stations online and SCE about 70 stations; and it is my understanding that more are being installed. (San Diego Gas & Electric (SDG&E) has had a similar mesonet of about 150 stations for about 5 years) The data is available on MesoWest and on via NWS graphical interface. However, neither MesoWest or the NWS page let's one parse out just these mesonets, so I have put together a couple pages, both in tabular and map/graphical form.

PG&E: Table, Map 
SCE: TableMap
SDG&E mesonet
These have both been added to the Mesonet section on my Meteorologist Links page.

Enjoy and please let me know of any comments or suggestions.

Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Email: jnull@ggweather.com  
Web: http://ggweather.com
Twitter: https://twitter.com/ggweather
Facebook: https://www.facebook.com/Golden-Gate-Weather-Services-151100414926621/




 

Posted

California Summer Temps Mostly Above Average - Recap

 

Meteorological summer (i.e., June, July, August) has ended and most of the Golden State ended up with above normal temperatures. The biggest anomalies were over the southern half of the California and over the northern interior.  



Jan Null, CCM
Certified Consulting Meteorologist
Golden Gate Weather Services
Phone: (408) 379-7500
Email: jnull@ggweather.com  
Web: http://ggweather.com
Twitter: https://twitter.com/ggweather
Facebook: https://www.facebook.com/Golden-Gate-Weather-Services-151100414926621/

 

Posted