A 30-Year Climatology of A 30-Year Climatology of Hourly Precipitation Across Hourly Precipitation Across

the Western Carolinas the Western Carolinas

Scott KrentzScott Krentz

Charles DaltonCharles Dalton

OverviewOverview

• Test Hypothesis Previous 10-year Study

• Methodology

• Results

• Unexpected Observation

• Concluding Remarks

Previous 10-year AnalysisPrevious 10-year Analysis

• Only used KGSP data

• Qualitatively compared to KAVL

• Verified forecaster’s observations

• Hypothesized temporal relationship between mountain and non-mountain precipitation

MethodologyMethodology

• 30-year hourly datasets from NCDC

• 3 ASOS sites – 6 FP sites

• Data quality controlled (outliers < 0.1%)

• Hourly precipitation and frequencies

• Spreadsheets Charts

Cool Season (Oct-Mar) Hourly Frequencies(1971 - 2000)

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ResultsResults

Warm Season (Apr-Sep) Hourly Frequencies(1971 - 2000)

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ResultsResults

ResultsResultsSummer (JJA) Hourly Event Frequency Comparison

(1971 - 2000)

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ResultsResultsJune Hourly Event Frequency Comparison

(1971 - 2000)

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ResultsResultsJuly Hourly Event Frequency Comparison

(1971 - 2000)

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ResultsResultsAugust Hourly Event Frequency Comparison

(1971 - 2000)

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ResultsResultsSummer (JJA) Hourly Precipitation Totals Comparison

(1971 - 2000)

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June Hourly Precipitation Totals Comparison (1971 - 2000)

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ResultsResults

ResultsResultsJuly Hourly Precipitation Totals Comparison

(1971 - 2000)

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ResultsResultsAugust Hourly Precipitation Totals Comparison

(1971 - 2000)

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Unexpected ObservationUnexpected ObservationJune 6-Hour Frequency of

Occurrence Comparison (1971 - 2000)

10.33

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17.44 17.33

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16.22

12.33 11.89

24.56

18.11

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Unexpected ObservationUnexpected ObservationJuly 6-Hour Frequency of

Occurrence Comparison (1971 - 2000)

9.89

5.59

19.1418.17

9.78

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20.1119.57

10.00 9.78

25.81

15.16

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Unexpected ObservationUnexpected ObservationAugust 6-Hour Frequency of

Occurrence Comparison (1971 - 2000)

10.43

6.56

14.6215.16

9.78

7.53

17.74

14.62

10.229.57

24.84

16.02

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JJA 6hr Frequency of Occurrence Comparison (1900-2400 LST)

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Unexpected ObservationUnexpected Observation

Unexpected ObservationUnexpected Observation

• Definite Warm-Season Frequency Shift

• Climatological Basis for Forecasts and Seasonal Staffing

• Additional Study Removing Tropical Precipitation

• Potential for Study of July Mountain Precipitation Decrease

ConclusionsConclusions