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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Hour Ending In (LST)
Ev
en
ts kavl
kclt
kgsp
ResultsResults
Warm Season (Apr-Sep) Hourly Frequencies(1971 - 2000)
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Hour Ending In (LST)
Ev
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ts kavl
kclt
kgsp
ResultsResults
ResultsResultsSummer (JJA) Hourly Event Frequency Comparison
(1971 - 2000)
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75
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125
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Hour (LST)
Ev
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ts kavl
kclt
kgsp
ResultsResultsJune Hourly Event Frequency Comparison
(1971 - 2000)
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Hour (LST)
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ts kavl
kclt
kgsp
ResultsResultsJuly Hourly Event Frequency Comparison
(1971 - 2000)
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nts
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ResultsResultsAugust Hourly Event Frequency Comparison
(1971 - 2000)
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Hour (LST)
Ev
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ts kavl
kclt
kgsp
ResultsResultsSummer (JJA) Hourly Precipitation Totals Comparison
(1971 - 2000)
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he
s kavl
kclt
kgsp
June Hourly Precipitation Totals Comparison (1971 - 2000)
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he
s kavl
kclt
kgsp
ResultsResults
ResultsResultsJuly Hourly Precipitation Totals Comparison
(1971 - 2000)
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he
s kavl
kclt
kgsp
ResultsResultsAugust Hourly Precipitation Totals Comparison
(1971 - 2000)
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he
s kavl
kclt
kgsp
Unexpected ObservationUnexpected ObservationJune 6-Hour Frequency of
Occurrence Comparison (1971 - 2000)
10.33
8.67
17.44 17.33
11.67
8.44
18.33
16.22
12.33 11.89
24.56
18.11
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Hour (LST)
Perc
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t KCLT
KGSP
KAVL
Unexpected ObservationUnexpected ObservationJuly 6-Hour Frequency of
Occurrence Comparison (1971 - 2000)
9.89
5.59
19.1418.17
9.78
6.77
20.1119.57
10.00 9.78
25.81
15.16
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Hour (LST)
Pe
rce
nt KCLT
KGSP
KAVL
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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Hour (LST)
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rce
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KGSP
KAVL
JJA 6hr Frequency of Occurrence Comparison (1900-2400 LST)
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June July August
6-H
R F
req
ue
nc
ies
KCLT KGSP KAVL
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