State Climate Update for Arizona – Conditions through August 2005

 

 

August 2005                                                                                                                                   

August, at the heart of the monsoon season across Arizona, was wetter than average across the state. Precipitation was of the 70th-90th percentile across the state, except for in east-central Arizona (CD 4), where precipitation was only slightly above average (55th percentile). However, the monsoon season typically does not significantly alter drought conditions in Arizona. The impact of the very wet fall and winter season of 2004-05 is still evident in Palmer Drought Severity Index values across the state. Values through August indicate very wet current conditions in all regions of the state except for in southeastern Arizona (CD 7), where drought recovery has been slowest. With humidity and precipitation typically come lower temperatures in Arizona, and this was the case for August across the state (28th – 73rd percentile).

 

 

Temperature

Precipitation

PDSI

CD1

64.0%

83.8% (0)

96.4%

CD2

28.8%

76.6% (0)

88.3%

CD3

52.3%

70.3% (0)

90.1%

CD4

36.9%

55.0% (0)

71.2%

CD5

73.9%

90.1% (0)

99.1%

CD6

66.7%

82.9% (0)

91.9%

CD7

34.2%

72.1% (0)

46.9%

 

1-month percentiles of temperature, precipitation (with drought category), and Palmer Drought Severity Index for the 7 Arizona climate divisions


 

 

June 2005 – August 2005                                                                                                

Three-month precipitation values that represent the traditional summer season (monsoon season is approximately July through September) indicate above-average precipitation across western and south-central Arizona, but rather dry conditions across eastern Arizona. For the 3-month period the northwest (CD 1), west central (CD 3), southwest (CD 5), and south-central (CD 6) areas of the state recorded slightly to well above average precipitation. In eastern Arizona precipitation was below normal and of a magnitude indicative of “moderate drought” in the southeastern part of the state (CD 7). Temperatures during the three months were rather mild relative to recent decades, but higher than the long-term median.

 

 

Temperature

Precipitation

CD1

71.2%

81.1% (0)

CD2

52.3%

47.8% (0)

CD3

67.6%

55.9% (0)

CD4

57.7%

42.3% (0)

CD5

79.3%

86.5% (0)

CD6

87.4%

73.0% (0)

CD7

85.6%

23.4% (2)

 

3-month percentiles of temperature, and precipitation (with drought category) for the 7 Arizona climate divisions


 

March 2005 – August 2005                                                                                             

Six-month precipitation values indicate evidence of drought conditions in southeastern (CD 7; moderate drought) and east-central (CD 4; abnormally dry) Arizona. Precipitation across the northeastern portion of the state (CDs 2 and 4) for the past six months was only slightly below normal, while the western (CDs 1 and 5) and south-central (CD 6) areas were rather wet. Statewide, temperatures were above the long-term median over the past 6 months, but not approaching unprecedented levels.

 

 

Temperature

Precipitation

CD1

72.1%

65.8% (0)

CD2

67.6%

46.8% (0)

CD3

73.0%

45.1% (0)

CD4

70.3%

35.1% (1)

CD5

75.7%

73.9% (0)

CD6

82.0%

53.2% (0)

CD7

82.9%

18.9% (2)

 

6-month percentiles of temperature, and precipitation (with drought category) for the 7 Arizona climate divisions


 

September 2004 – August 2005                                                                                    

There is no evidence of drought conditions within the state when examining 12-month precipitation values. Most regions were characterized by well above normal precipitation, including totals in the 90th percentile for 6 of the 7 regions, and the wettest September-August period on record for 2 of the regions (CDs 2 and 3). The relatively drier area continues to be across the southeast (CD 7; 69th percentile). Still, the 12-month precipitation total in that region was above the long-term median. Temperatures across the state were above normal for the past 12-month period, but again, the values were not near unprecedented levels.

 

 

Temperature

Precipitation

CD1

77.3%

99.1% (0)

CD2

82.7%

100% (0)

CD3

77.3%

100% (0)

CD4

78.2%

91.8% (0)

CD5

73.6%

99.1% (0)

CD6

83.6%

95.5% (0)

CD7

67.3%

69.1% (0)

 

12-month percentiles of temperature, and precipitation (with drought category) for the 7 Arizona climate divisions


 

September 2003 – August 2005                                                                                    

Twenty-four month precipitation values continue to indicate rather wet conditions across the state, as all regions but the southeast (CD 7) were comfortably above the long-term median value, and well above across the western portion of the state. The 2-year precipitation total was near average across southeastern Arizona (CD 7), the driest region over the past two years. Mean temperatures for the 2-year period reflect the trend toward warming over the last several decades, as temperatures were of the 83rd – 98th percentile across the state.

 

 

Temperature

Precipitation

CD1

83.5%

92.7% (0)

CD2

89.9%

83.5% (0)

CD3

90.8%

88.1% (0)

CD4

95.4%

67.9% (0)

CD5

89.9%

96.3% (0)

CD6

89.9%

85.3% (0)

CD7

82.6%

52.3% (0)

 

24-month percentiles of temperature, and precipitation (with drought category) for the 7 Arizona climate divisions


 

September 2002 – August 2005                                                                                    

Precipitation totals for the longer 3-year period indicate conditions that are not as wet when considering the past two years, as a portion of the very dry year of 2002 enters the timeframe. Relatively dry conditions are evident across the southeastern portion of the state (CD 7; 25th percentile), where the total precipitation for the period is suggestive of “abnormally” conditions. Elsewhere, precipitation was either at or above the long-term median for the 3-year period. Temperatures for the period were well above the historical median; however, the longer 3-year time period likely illustrates the more general climatic changes of the past several decades rather than shorter term anomalies.

 

 

Temperature

Precipitation

CD1

86.1%

89.8% (0)

CD2

91.7%

75.9% (0)

CD3

93.5%

85.2% (0)

CD4

97.2%

50.0% (0)

CD5

92.6%

93.5% (0)

CD6

93.5%

79.6% (0)

CD7

87.0%

25.9% (1)

 

36-month percentiles of temperature, and precipitation (with drought category) for the 7 Arizona climate divisions


September 2001 – August 2005                                                                                    

Forty eight-month precipitation values indicate the presence of longer-term drought conditions across two areas of the state, with abnormally dry conditions across another three areas. All regions within the state, except for the southwest (CD 5), have been characterized by less than average precipitation over the 4-year period. Precipitation totals for the period indicate “abnormally dry” conditions across the northeastern (CD 2), west-central (CD 3), and south-central (CD 6) portions of the state. Long-term conditions suggestive of “severe drought” exist across southeastern (CD 7) and east-central (CD 4) Arizona, as both are characterized by 48-month precipitation that is in the 9th-10th percentile range. Temperatures for the 4-year period are near unprecedented highs but, again, this is a likely to be a reflection of longer-term trends rather than shorter-term anomalies.

 

 

Temperature

Precipitation

CD1

88.8%

46.7% (0)

CD2

92.5%

39.3% (1)

CD3

97.2%

36.5% (1)

CD4

98.1%

9.4% (3)

CD5

92.5%

76.6% (0)

CD6

96.3%

34.6% (1)

CD7

96.3%

10.3% (3)

 

48-month percentiles of temperature, and precipitation (with drought category) for the 7 Arizona climate divisions


 

 

  

 

                                                                                                                               

                       

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

 

 

                                                


 

 

 

 

 

 

 

 

Summary                                                                                                                             

Corresponding with the heart of the monsoon season, August 2005 was characterized by rather wet conditions across the state, and the wet fall and winter conditions of 2004-05 were still reflected in high (wet) Palmer Drought Index Values. Problematic was the re-emergence of dry conditions across southeastern Arizona over the past 3-6 months, associated with a dry spring and late onset of the monsoon. There exists little or no evidence of drought across Arizona over the past 12-to-36 months with generally much greater precipitation than normal during the period. However, long-term dryness and drought are evident on the 48-month time frame. The most critical areas of dryness over the past 4 years are located across southeastern and east-central Arizona. In these areas, precipitation was of an amount suggestive of “severe drought”. Included within the 4-year period is the very dry year of 2002, which is certain to have a significant influence. Overall, short-term conditions indicate a bit of a shift from the unusual wetness of fall and winter to a rather dry spring and early summer, followed by a rather wet month of August. The impacts of the wetness earlier in the year have persisted such that the Palmer Drought Severity Index values continue to indicate unusual wetness across most of the state; the increased precipitation of fall and winter has clearly provided relief to the longer-term drought condition. Still, the southeastern and east-central regions continue to struggle with long-term precipitation totals suggestive of drought, and southeastern Arizona has shown recent signs of re-emerging dry conditions on the short-term.