December California Climatology

Happy New Year and Best Wishes for a healthy, happy and properous 2015.


December 2014 was a wet and warm month across the Golden State. Precipitation ranged from "only" 120% of normal at Eureka to 294% at Los Angeles and 297% at San Jose.  December maxima were well above normal, ranging from 1.6 degrees above normal at Redding to 5.9 above normal at Sacramento; with the exception of Los Angeles whose maxima were 0.2 below normal.


December California Key City Climatology
http://ggweather.com/calif/dec2014.htm 


December Max Anomaly Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dTxdep.gif 


December Mean Anomaly Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dTvdep.gif 


December Min Anomaly Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dTndep.gif 


December Precipitation Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dP.gif 


December Precipitation % of Normal Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc30dPpct.gif 


July - December Precipitation Table
http://www.cnrfc.noaa.gov/awipsProducts/RNOWRKCLI.php 


July - December % of Normal Map
http://www.wrcc.dri.edu/cgi-bin/anomimage.pl?wrc6mPpct.gif 


Northern Sierra Nevada 8-Station Index
http://cdec.water.ca.gov/cgi-progs/products/PLOT_ESI.pdf 


Southern Sierra Nevada 5-Station Index
http://cdec.water.ca.gov/cgi-progs/products/PLOT_FSI.pdf 


California Snow Water Content
http://cdec.water.ca.gov/cgi-progs/products/PLOT_SWC.pdf 

Jan Null, CCM
http://ggweather.com 

Posted

Should You Walk or Run in the Rain?

With the recent rains I have been re-asked the eternal question: "Should I Walk or Run in the Rain?" This is a classic question that meteorologists get asked and upon which we have probably spent way too much time. So, does a person make impact with more droplets as they run faster even though they are exposed for a shorter period of time? Or do more drops hit the front of a running person than on their head and shoulders when they run instead of walk?

There have even been a number of studies to "scientifically'' calculate whether it's better to run or walk to shelter. One of the simpler studies had people wear a piece of cardboard over their heads and in front of them as they walked or ran through the rain and then the number of drops that marked the cardboard were counted. A more detailed effort from the National Climatic Data Center in Asheville, North Carolina had their experimental subjects wear identical moisture absorbing clothing as they walked 100 yards at 3 mph and then ran the same course at 9 mph. Their clothing was then weighed to find out how much water was absorbed. They found that speed helps ... the person who ran the course absorbed 40 percent less water than the walker!

And of course someone, again with way too much time on their hands, has put up a website to calculate how wet you would get based upon your size, speed and the rate of rainfall. See http://www.dctech.com/physics/notes/0006.php and http://www.dctech.com/physics/notes/0005.php.

Stay dry!

Jan Null, CCM
Golden Gate Weather Services
http://ggweather.com

Posted

Not Necessarily the Worst California Drought in 1200 Years!

In the past week there has been extensive media coverage and headlines about "the worst California drought in 1200 years". This was based on a paper to be published in Geophysical Research Letters by the AGU. However a thorough reading of that paper,"How unusual is the 2012-2014 California drought?", indicates that this "worst" declaration should have at least a few asterisks. The article is not inaccurate but it takes only a limited view at looking at the current California drought.


- The study defines drought using the Palmer Drought Severity Index (PDSI). This is an agricultural index, based on soil-moisture as a function of both temperatue and precipitation. While, agriculture is incredibly important in California, it is not necessarily the best metric for the state's overall water deficit and its impacts.


- The paper also does not look at all of California. Instead it only examines the PDSI for central and southern California (i.e. NCDC California Climate Divisions 4, 5, 6, 7). This methodolgy gives a skewed prespective since much of the water used throughout the entire state originates in northern California (i.e., Climate Divisions 1,2,3) and the 3-year deficit has been less there than in the sampled southern two-thirds of the state. [For additional context see the just released NOAA California Drought Assessment.]


The bottom line is that the paper really only speaks to agricultural drought in central and southern California while both the Ranked 3-year Precipitation and PDSI show that currently the drought in northern California is only on the order of the 4th or 5th driest in the past 120 years; certainly not the driest in the past 1200 years statewide.


Jan Null, CCM
Golden Gate Weather Services

 

Links referenced above:
http://www.whoi.edu/page.do?pid=50242&tid=3622&cid=207049 
http://www.drought.gov/drought/content/products-current-drought-and-monitoring-drought-indicators/palmer-drought-severity-index 

 
http://cpo.noaa.gov/sites/cpo/MAPP/Task%20Forces/DTF/californiadrought/California_Drought_2-pager.pdf 
 

Posted

Not Necessarily the Worst Drought in 1200 years!

In the past week there has been extensive media coverage and headlines about "the worst California drought in 1200 years". This was based on a paper to be published in Geophysical Research Letters by the AGU. However a thorough reading of that paper,"How unusual is the 2012-2014 California drought?", indicates that this "worst" declaration should have at least a few asterisks. The article is not inaccurate but it takes only a limited view at looking at the current California drought.


- The study defines drought using the Palmer Drought Severity Index (PDSI). This is an agricultural index, based on soil-moisture as a function of both temperatue and precipitation. While, agriculture is incredibly important in California, it is not necessarily the best metric for the state's overall water deficit and its impacts.


- The paper also does not look at all of California. Instead it only examines the PDSI for central and southern California (i.e. NCDC California Climate Divisions 4, 5, 6, 7). This methodolgy gives a skewed prespective since much of the water used throughout the entire state originates in northern California (i.e., Climate Divisions 1,2,3) and the 3-year deficit has been less there than in the sampled southern two-thirds of the state. [For additional context see the just released NOAA California Drought Assessment.]


The bottom line is that the paper really only speaks to agricultural drought in central and southern California while both the Ranked 3-year Precipitation and PDSI show that currently the drought in northern California is only on the order of the 4th or 5th driest in the past 120 years; certainly not the driest in the past 1200 years statewide.

Jan Null, CCM
Golden Gate Weather Services


Posted

Impressive California 5-Day Totals

Compilation of 5-day rainfall statewide totals and current percent of normal.

 
...Northern California...

 

 

 

 

 

5-day

Season-

Current

 

29-Nov

30-Nov

1-Dec

2-Dec

3-Dec

Total

to-Date

% Normal

Crescent City

0.22

0.00

T

0.06

0.24

0.52

14.05

85

Eureka

0.76

T

0.00

0.10

0.27

1.13

12.16

125

Ukiah

0.11

0.37

0.18

0.30

1.67

2.63

9.05

121

Redding

M

0.29

0.08

0.12

1.30

1.79

11.02

137

Sacramento Exec AP

M

0.13

0.01

0.71

2.20

3.05

5.22

143

Sacramento - Csus

M

0.10

0.00

0.53

1.82

2.45

4.65

112

Santa Rosa

0.21

0.37

M

M

1.23

1.81

6.43

85

San Francisco

0.06

0.29

0.00

1.45

1.79

3.59

6.79

137

SFO Int'L Airport

T

0.29

T

1.55

1.55

3.39

5.86

152

Oakland Airport

0.02

0.22

T

1.18

1.06

2.48

5.05

121

Livermore

T

0.44

0.02

1.40

1.01

2.87

4.18

127

Mtn View - Moffett

0.34

0.46

0.12

1.14

1.84

3.90

5.08

190

San Jose

0.70

0.56

0.01

1.13

1.17

3.57

4.94

164

 

 

 

 

 

 

 

 

 

...Central California...

 

 

 

 

 

5-day

Season-

Current

 

29-Nov

30-Nov

1-Dec

2-Dec

3-Dec

Total

to-Date

% Normal

Stockton

0.04

0.43

0.00

1.10

0.17

1.74

3.62

121

Modesto

0.37

0.25

0.00

0.87

0.09

1.58

2.99

121

Merced

0.16

0.03

0.00

0.66

0.06

0.91

2.08

87

Madera

0.00

0.00

0.00

0.49

T

0.49

1.32

55

Fresno

0.00

0.01

0.00

0.42

T

0.43

1.51

75

Hanford

0.00

T

0.00

0.37

0.00

0.37

1.18

67

Bakersfield

0.00

0.00

0.00

0.44

0.00

0.44

1.1

97

Salinas

0.02

0.07

T

0.89

0.07

1.05

3.05

130

Paso Robles

0.00

0.17

T

0.66

0.07

0.90

2

95

Santa Maria

0.00

T

0.00

0.71

0.02

0.73

2.05

90

 

 

 

 

 

 

 

 

 

...Southern California...

 

 

 

 

 

5-day

Season-

Current

 

29-Nov

30-Nov

1-Dec

2-Dec

3-Dec

Total

to-Date

% Normal

Sandberg

0.00

0.04

0.00

1.32

0.49

1.85

2.75

159

Palmdale

0.00

T

0.00

1.18

0.01

1.19

1.37

73

Lancaster

0.00

T

0.00

1.10

0.07

1.17

1.54

111

Santa Barbara

0.00

T

T

2.06

0.22

2.28

3.72

127

Camarillo

0.00

0.07

0.00

1.15

0.12

1.34

2.13

93

Burbank - Bob Hope

0.00

0.43

0.00

1.06

0.04

1.53

2.32

92

LAX Int'L Airport

0.00

0.22

0.00

1.05

0.17

1.44

2.14

102

Los Angeles / Usc

0.00

0.21

0.00

1.15

0.20

1.56

2.19

102

Long Beach

0.00

0.05

0.10

0.90

0.40

1.45

2.58

128

Fullerton

0.00

0.03

0.01

0.58

0.22

0.84

1.86

81

Irvine - John Wayne

0.00

0.02

0.00

0.29

0.09

0.40

0.78

33

Oceanside

0.00

0.00

0.00

0.09

0.35

0.44

1.75

75

Ramona

0.00

T

0.00

0.06

0.31

0.37

2.27

86

San Diego - Lindbergh

0.00

0.00

0.00

0.02

0.26

0.28

1.13

59

Ontario

0.00

0.16

0.00

0.84

0.16

1.16

2.96

121

Riverside

0.00

T

0.00

0.05

0.04

0.09

0.69

39

Palm Springs

0.00

0.00

0.00

0.13

0.03

0.16

1.62

82

Thermal

0.00

0.00

0.00

T

0.01

0.01

0.46

43

Campo

0.00

0.00

0.00

0.08

1.14

1.22

3.76

108

 

Jan Null, CCM
Golden Gate Weather Services

Posted

Biggest 2-day and 3-day Rain Events in San Francisco

Through 7 am San Francisco had received 1.36" of rainfall since midnight, which combined with 1.61" received yesterday gives a 2-day total of 2.97".  With more rain on the way this looks to be the rainiest 2 days in San Francisco since at least January 2008.

The table below has the rainiest 2-day and 3-day events since 2000.

It should be noted that the one-day record in San Francisco is 5.54" on Nov. 5, 1994.  http://ggweather.com/sf/top%2020%20wettest.html 

 

    2-day 3-day
1/18/2010 0.99    
1/19/2010 1.24 2.23  
1/20/2010 1.03 2.27 3.26
       
2/15/2009 2.18    
2/16/2009 0.79 2.97  
2/17/2009 0.87 1.66 3.84
       
1/25/2008 3.19    
1/26/2008 0.38 3.57  
1/27/2008 0.38 0.76 3.95
       
12/17/2005 1.14    
12/18/2005 2.15 3.29  
12/19/2005 0.20 2.35 3.49
       
12/16/2004 0.84    
12/17/2004 2.61 3.45  
12/18/2004 0.31 2.92 3.76
       
12/13/2002 2.99    
12/14/2002 0.81 3.80  
12/15/2002 0.42 1.23 4.22
       
2/11/2000 1.23    
2/12/2000 0.53 1.76  
2/13/2000 2.08 2.61 3.84
 Jan Null, CCM
Golden Gate Weather Services
Posted

California Drought - Good News, Bad News

Great soaking rain across much of California and we will see many rainfall season-to-date percent of normal rainfall jump significantly.  Some to above normal. (see http://www.cnrfc.noaa.gov/awipsProducts/RNOWRKCLI.php  which is reissued daily at 6 PM).  This is all good and every inch of rain helps ease the drought.


But, looking at the broader picture of the deficits from the last 3 seasons (2011-12, 2012-13, 2013-14) shows what a long uphill battle it will be.  For example, the 3-season deficit for San Francisco at the beginning of the rainfall season was 26.07 inches. If you add that to the 23.65 inches needed for this season to ultimately reach normal we would need 49.73 inches to be at "normal".  The all-time rainiest season in SF history was 1861-62 when there was 49.27".  Or for every 1 inch of rain in San Francisco we will only erase about 3% of this long term deficit!


Below is a table of the rainfall to date (through 6 pm last night) for the combined last 3 seasons plus this season-to-date, thge deficit and the percent of normal.

 

3+ seasons to date

 

Rain

Normal

Deficit

% Normal

...Northern California...

 

 

 

 

 

 

 

 

 

Crescent City

161.95

208.18

-46.23

78%

Eureka

105.93

130.18

-24.25

81%

Ukiah

79.01

119.21

-40.20

66%

Redding

79.23

111.53

-32.30

71%

Sacramento Exec Airport

39.46

59.02

-19.56

67%

Sacramento - Csus

42.23

64.77

-22.54

65%

Santa Rosa

69.81

116.13

-46.32

60%

San Francisco

48.27

75.63

-27.36

64%

SFO Int'L Airport

37.75

65.60

-27.85

58%

Oakland Airport

41.68

66.44

-24.76

63%

Livermore

28.37

50.31

-21.94

56%

Mountain View - Moffett

25.31

46.59

-21.28

54%

San Jose

25.43

47.63

-22.20

53%

 

 

 

 

 

...Central California...

 

 

 

 

 

 

 

 

 

Stockton

27.96

45.05

-17.09

62%

Modesto

26.85

41.70

-14.85

64%

Merced

21.34

39.82

-18.48

54%

Madera

21.59

38.40

-16.81

56%

Fresno

19.72

36.43

-16.71

54%

Hanford

13.05

32.03

-18.98

41%

Bakersfield

11.15

20.49

-9.34

54%

Salinas

27.40

40.72

-13.32

67%

Paso Robles

19.49

40.36

-20.87

48%

Santa Maria

21.75

44.02

-22.27

49%

 

 

 

 

 

...Southern California...

 

 

 

 

 

 

 

 

 

Sandberg

16.18

38.63

-22.45

42%

Palmdale

10.00

26.74

-16.74

37%

Lancaster

8.57

23.48

-14.91

36%

Santa Barbara

29.01

56.10

-27.09

52%

Camarillo

19.44

47.87

-28.43

41%

Burbank - Bob Hope

20.90

54.34

-33.44

38%

LAX Int'L Airport

19.80

40.47

-20.67

49%

Los Angeles / Usc

21.40

46.83

-25.43

46%

Long Beach

19.88

38.69

-18.81

51%

Fullerton

17.60

43.86

-26.26

40%

Irvine - John Wayne

15.19

42.31

-27.12

36%

Oceanside

19.88

43.25

-23.37

46%

Ramona

28.85

50.64

-21.79

57%

San Diego - Lindbergh

20.04

32.84

-12.80

61%

Ontario

20.57

47.49

-26.92

43%

Riverside

13.17

38.91

-25.74

34%

Palm Springs

7.73

19.15

-11.42

40%

Thermal

5.97

10.64

-4.67

56%

Campo

29.78

50.56

-20.78

59%

 

Jan Null, CCM
Golden Gate Weather Services

Wettest SF Day Since ?

Through 8 am this morning downtown San Francisco had received 1.13 inches of rain.  Below are the 25 rainiest days (midnight to midnight) in downtown SF since July 1, 2009.  The current total would make it the only the wettest day since last February, BUT with rain continuing to fall today's total should climb rapidly up the list.

rank

date

rain

1

10/13/2009

2.48

2

2/15/2009

2.18

3

3/14/2012

1.47

4

1/20/2012

1.41

5

12/19/2010

1.27

6

2/22/2009

1.24

7

1/19/2010

1.24

8

3/24/2011

1.24

9

4/12/2012

1.24

10

3/24/2012

1.23

11

12/28/2010

1.21

12

11/7/2010

1.18

13

4/17/2010

1.17

14

12/25/2012

1.15

15

2/8/2014

1.15

16

2/9/2014

1.13

17

3/19/2011

1.12

18

2/28/2014

1.12

19

12/2/2012

1.06

20

2/19/2011

1.05

21

2/17/2011

1.04

22

1/20/2010

1.03

23

12/8/2010

1.02

24

12/23/2012

1.00

 

Jan Null, CCM
Golden Gate Weather Services

Posted

November California Rain and Temperature Summary

Despite the recent rain, California ended up with below normal rainfall in November 2014. Precipitation ranged from 82% of normal at Redding to 48% at Sacramento in northern California, 93% at San Jose to 37% in Fresno in central California and from 46% in Los Angeles to 37% in San Diego.


In terms of the droughtit is important to note, that even reaching "normal to date" rainfall for this season does not address the carry-over deficits from the past two seasons.

Temperatures were universally above normal, ranging from 1.8 above normal at Redding to 5.3 above normal at San Diego.


See http://ggweather.com/calif/nov2014.htm 

 Jan Null, CCM
Golden Gate Weather Services

Posted