Fort Supply Reservoir
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Supply Reservoir clear sky chart from 2005-11-06 to 2024-11-28.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	7% 5% 2 4 3 3 3 3 5% 7% 58%	105219
	Night	7% 4 2 4 3 3 3 3 5% 7% 59%	102964
Transparency	Day	26% 5% 10% 24% 25% 9%	104986
	Night	25% 5% 10% 24% 26% 10%	102787
Seeing	Day	9% 8% 30% 32% 17% 4	15518
	Night	9% 9% 37% 35% 10%	25445

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	6% 8% 2 5% 4 4 4 4 5% 5% 54%	2847
	11th to 20th	Day	5% 5% 2 5% 3 3 4 4 5% 8% 57%	2850
	21st to end	Day	10% 9% 3 6% 3 3 3 3 4 5% 52%	3139
February	1st to 10th	Day	8% 9% 3 4 3 2 2 3 4 6% 54%	1900
	11th to 20th	Day	6% 6% 2 6% 3 3 4 3 3 6% 59%	1849
	21st to end	Day	6% 6% 2 5% 3 4 3 3 4 6% 59%	1570
March	1st to 10th	Day	7% 6% 2 4 2 2 2 2 4 6% 63%	3177
	11th to 20th	Day	7% 5% 2 4 3 3 3 3 4 6% 59%	3480
	21st to end	Day	10% 8% 3 6% 4 4 5% 4 5% 6% 46%	3814
April	1st to 10th	Day	7% 5% 2 5% 4 2 3 3 4 6% 60%	2194
	11th to 20th	Day	11% 6% 2 5% 3 4 3 4 5% 6% 52%	2251
	21st to end	Day	12% 5% 2 4 3 3 3 3 5% 6% 53%	2467
May	1st to 10th	Day	12% 5% 2 5% 4 4 3 3 5% 6% 52%	4120
	11th to 20th	Day	9% 4 2 5% 3 4 4 4 5% 7% 53%	4082
	21st to end	Day	9% 4 2 5% 4 3 4 3 6% 6% 54%	4489
June	1st to 10th	Day	6% 4 2 5% 3 4 5% 4 6% 8% 54%	2470
	11th to 20th	Day	5% 3 1 4 3 4 5% 4 6% 7% 58%	2470
	21st to end	Day	6% 3 2 4 4 3 4 3 6% 8% 58%	2470
July	1st to 10th	Day	7% 5% 2 6% 4 4 5% 4 5% 8% 52%	4120
	11th to 20th	Day	4 3 1 4 3 4 4 4 6% 8% 60%	4120
	21st to end	Day	3 2 1 3 3 4 4 4 6% 10% 59%	4466
August	1st to 10th	Day	8% 4 2 5% 3 4 4 3 6% 7% 55%	4103
	11th to 20th	Day	4 4 1 4 3 3 4 4 5% 8% 60%	3895
	21st to end	Day	4 3 1 3 2 3 4 3 6% 9% 62%	4180
September	1st to 10th	Day	9% 4 2 4 2 4 3 3 4 6% 58%	2159
	11th to 20th	Day	8% 3 1 4 3 3 4 4 5% 7% 57%	2090
	21st to end	Day	6% 3 1 5% 3 3 3 3 4 6% 63%	2090
October	1st to 10th	Day	6% 3 1 3 2 2 2 2 3 4 74%	3480
	11th to 20th	Day	5% 2 1 3 2 2 2 2 5% 7% 70%	3246
	21st to end	Day	6% 3 1 3 2 2 2 2 5% 5% 69%	3289
November	1st to 10th	Day	6% 3 1 4 3 2 3 2 4 4 67%	1763
	11th to 20th	Day	5% 5% 1 3 2 2 3 2 4 7% 66%	1800
	21st to end	Day	9% 5% 2 4 3 2 3 2 3 5% 63%	1773
December	1st to 10th	Day	6% 5% 2 4 3 3 3 3 5% 7% 58%	1710
	11th to 20th	Day	8% 6% 2 4 3 3 4 3 4 5% 59%	2161
	21st to end	Day	7% 12% 4 7% 5% 4 3 2 4 6% 46%	3135
January	1st to 10th	Night	8% 7% 4 5% 3 4 4 3 4 5% 53%	4108
	11th to 20th	Night	4 4 2 5% 4 4 4 4 4 6% 60%	4120
	21st to end	Night	12% 8% 2 5% 3 3 3 2 4 4 52%	4532
February	1st to 10th	Night	9% 8% 2 6% 4 3 3 3 4 5% 54%	2290
	11th to 20th	Night	9% 6% 2 6% 4 4 3 3 5% 6% 53%	2218
	21st to end	Night	7% 4 2 4 3 4 3 3 5% 6% 59%	1884
March	1st to 10th	Night	5% 5% 2 4 3 2 3 3 4 6% 64%	3684
	11th to 20th	Night	8% 4 2 4 3 3 3 3 4 6% 59%	3480
	21st to end	Night	7% 7% 2 5% 4 3 4 3 5% 6% 54%	3817
April	1st to 10th	Night	6% 4 1 3 3 4 3 3 4 6% 61%	1981
	11th to 20th	Night	9% 4 2 5% 3 4 4 3 7% 7% 52%	1877
	21st to end	Night	12% 4 2 4 3 3 4 4 4 6% 54%	1710
May	1st to 10th	Night	12% 5% 1 5% 4 3 3 4 5% 6% 51%	2850
	11th to 20th	Night	9% 3 2 5% 3 3 5% 3 7% 7% 53%	2823
	21st to end	Night	7% 4 1 4 3 3 4 3 6% 8% 57%	3098
June	1st to 10th	Night	5% 4 1 4 3 4 3 4 7% 11% 55%	1710
	11th to 20th	Night	5% 2 1 4 3 3 3 4 7% 11% 56%	1710
	21st to end	Night	6% 3 2 3 3 2 4 3 5% 10% 58%	1710
July	1st to 10th	Night	5% 4 2 5% 3 3 5% 4 6% 8% 56%	2850
	11th to 20th	Night	4 2 1 3 3 4 4 5% 7% 12% 56%	2850
	21st to end	Night	3 2 1 3 3 3 4 4 8% 10% 58%	3097
August	1st to 10th	Night	5% 3 1 5% 4 5% 6% 4 7% 9% 51%	2836
	11th to 20th	Night	5% 3 1 4 3 4 5% 4 7% 12% 52%	2926
	21st to end	Night	3 2 1 4 3 3 4 3 7% 10% 60%	3487
September	1st to 10th	Night	8% 3 1 3 3 2 3 3 4 6% 63%	2019
	11th to 20th	Night	8% 4 2 5% 3 3 3 3 5% 5% 58%	2090
	21st to end	Night	5% 3 1 4 3 3 3 3 4 6% 64%	2090
October	1st to 10th	Night	5% 2 1 3 2 2 2 2 3 5% 74%	3480
	11th to 20th	Night	4 2 1 2 2 2 3 2 4 6% 72%	3640
	21st to end	Night	5% 2 1 2 1 2 2 3 3 7% 72%	4262
November	1st to 10th	Night	7% 4 1 3 2 1 2 3 5% 6% 66%	2535
	11th to 20th	Night	4 4 1 3 3 2 2 3 4 6% 68%	2600
	21st to end	Night	8% 5% 1 4 3 3 3 3 4 5% 63%	2562
December	1st to 10th	Night	6% 6% 1 4 3 3 3 3 5% 7% 60%	2470
	11th to 20th	Night	8% 5% 1 5% 3 3 3 3 5% 6% 59%	3036
	21st to end	Night	7% 8% 2 5% 4 4 4 3 5% 6% 50%	4532

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	30% 5% 8% 24% 28% 4	2848
	11th to 20th	Day	26% 5% 15% 21% 26% 8%	2850
	21st to end	Day	35% 4 6% 24% 27% 4	3139
February	1st to 10th	Day	32% 3 11% 25% 22% 7%	1900
	11th to 20th	Day	30% 3 9% 26% 23% 10%	1859
	21st to end	Day	27% 4 6% 25% 25% 14%	1570
March	1st to 10th	Day	24% 3 8% 18% 23% 24%	3177
	11th to 20th	Day	26% 6% 10% 22% 29% 8%	3480
	21st to end	Day	35% 8% 11% 24% 18% 4	3814
April	1st to 10th	Day	25% 5% 8% 24% 25% 13%	2194
	11th to 20th	Day	32% 5% 9% 23% 20% 11%	2254
	21st to end	Day	31% 5% 10% 26% 23% 5%	2467
May	1st to 10th	Day	32% 7% 12% 18% 19% 12%	4120
	11th to 20th	Day	28% 7% 13% 27% 19% 5%	4086
	21st to end	Day	29% 7% 10% 19% 19% 16%	4489
June	1st to 10th	Day	25% 8% 19% 26% 15% 7%	2470
	11th to 20th	Day	23% 7% 12% 24% 25% 8%	2470
	21st to end	Day	23% 5% 13% 25% 24% 10%	2470
July	1st to 10th	Day	30% 6% 10% 24% 23% 7%	4056
	11th to 20th	Day	22% 5% 11% 29% 27% 6%	4051
	21st to end	Day	20% 5% 12% 28% 29% 4	4325
August	1st to 10th	Day	29% 4 12% 29% 22% 5%	4090
	11th to 20th	Day	23% 5% 12% 25% 29% 5%	3934
	21st to end	Day	20% 5% 12% 30% 28% 6%	4179
September	1st to 10th	Day	27% 6% 8% 22% 23% 14%	2159
	11th to 20th	Day	25% 6% 11% 21% 30% 6%	2090
	21st to end	Day	22% 5% 10% 22% 29% 11%	2090
October	1st to 10th	Day	17% 3 6% 15% 42% 18%	3480
	11th to 20th	Day	16% 2 10% 27% 27% 18%	3246
	21st to end	Day	19% 2 6% 24% 35% 13%	3289
November	1st to 10th	Day	21% 3 8% 22% 31% 15%	1763
	11th to 20th	Day	20% 3 7% 26% 31% 12%	1800
	21st to end	Day	27% 3 5% 24% 29% 12%	1773
December	1st to 10th	Day	26% 5% 10% 28% 25% 6%	1710
	11th to 20th	Day	27% 5% 8% 23% 28% 9%	2159
	21st to end	Day	39% 5% 8% 19% 23% 6%	3135
January	1st to 10th	Night	32% 6% 8% 28% 22% 5%	4108
	11th to 20th	Night	23% 7% 15% 23% 26% 7%	4120
	21st to end	Night	35% 5% 7% 20% 27% 6%	4532
February	1st to 10th	Night	34% 4 8% 24% 22% 9%	2290
	11th to 20th	Night	31% 5% 9% 21% 24% 9%	2218
	21st to end	Night	26% 4 6% 22% 26% 16%	1884
March	1st to 10th	Night	22% 4 6% 21% 25% 22%	3684
	11th to 20th	Night	25% 5% 9% 25% 24% 11%	3480
	21st to end	Night	29% 7% 10% 25% 22% 7%	3817
April	1st to 10th	Night	24% 5% 9% 22% 25% 15%	1981
	11th to 20th	Night	29% 6% 12% 23% 19% 10%	1877
	21st to end	Night	30% 6% 11% 26% 23% 5%	1710
May	1st to 10th	Night	32% 9% 10% 15% 20% 15%	2850
	11th to 20th	Night	27% 9% 15% 27% 17% 5%	2824
	21st to end	Night	24% 7% 13% 20% 19% 17%	3099
June	1st to 10th	Night	23% 7% 18% 30% 16% 6%	1710
	11th to 20th	Night	22% 8% 13% 27% 24% 8%	1710
	21st to end	Night	22% 5% 12% 27% 23% 11%	1710
July	1st to 10th	Night	26% 4 13% 28% 24% 5%	2805
	11th to 20th	Night	20% 4 12% 28% 29% 7%	2796
	21st to end	Night	19% 4 15% 27% 30% 4	2999
August	1st to 10th	Night	26% 6% 12% 26% 24% 6%	2826
	11th to 20th	Night	25% 5% 11% 29% 25% 6%	2953
	21st to end	Night	20% 5% 14% 33% 24% 6%	3487
September	1st to 10th	Night	23% 5% 10% 24% 27% 11%	2019
	11th to 20th	Night	28% 5% 10% 20% 29% 9%	2090
	21st to end	Night	21% 4 9% 23% 31% 12%	2090
October	1st to 10th	Night	17% 3 5% 16% 38% 21%	3480
	11th to 20th	Night	15% 2 8% 23% 34% 18%	3640
	21st to end	Night	15% 2 5% 26% 36% 16%	4262
November	1st to 10th	Night	19% 4 9% 23% 27% 18%	2535
	11th to 20th	Night	19% 3 7% 26% 31% 13%	2600
	21st to end	Night	25% 3 6% 24% 28% 14%	2562
December	1st to 10th	Night	25% 3 9% 28% 28% 7%	2470
	11th to 20th	Night	27% 4 7% 25% 29% 8%	3037
	21st to end	Night	32% 5% 11% 21% 23% 8%	4532

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	8% 10% 42% 30% 9% 1	270
	11th to 20th	Day	15% 15% 34% 26% 9%	270
	21st to end	Day	7% 13% 43% 27% 9% 1	297
February	1st to 10th	Day	13% 13% 40% 28% 6% 1	270
	11th to 20th	Day	11% 11% 50% 20% 6% 2	270
	21st to end	Day	12% 13% 56% 17% 2	225
March	1st to 10th	Day	9% 11% 50% 23% 7%	270
	11th to 20th	Day	16% 13% 41% 20% 7% 2	270
	21st to end	Day	16% 16% 38% 24% 5% 1	297
April	1st to 10th	Day	13% 16% 40% 23% 7%	374
	11th to 20th	Day	14% 19% 43% 22% 2	452
	21st to end	Day	14% 18% 38% 21% 9% 1	647
May	1st to 10th	Day	13% 10% 41% 29% 6% 1	653
	11th to 20th	Day	14% 6% 30% 33% 15% 2	675
	21st to end	Day	9% 11% 35% 32% 11% 3	734
June	1st to 10th	Day	6% 6% 27% 38% 18% 6%	680
	11th to 20th	Day	6% 6% 29% 38% 19% 2	680
	21st to end	Day	6% 2 29% 42% 18% 3	680
July	1st to 10th	Day	6% 2 17% 35% 31% 9%	671
	11th to 20th	Day	3 2 14% 42% 32% 8%	668
	21st to end	Day	6% 1 11% 40% 35% 8%	739
August	1st to 10th	Day	6% 1 16% 41% 31% 5%	676
	11th to 20th	Day	7% 2 14% 41% 33% 4	584
	21st to end	Day	5% 2 15% 38% 29% 10%	539
September	1st to 10th	Day	11% 1 13% 35% 31% 9%	369
	11th to 20th	Day	6% 2 19% 47% 20% 6%	300
	21st to end	Day	9% 3 25% 30% 27% 7%	300
October	1st to 10th	Day	12% 4 30% 28% 21% 5%	300
	11th to 20th	Day	7% 6% 37% 35% 14% 1	300
	21st to end	Day	16% 9% 35% 24% 12% 4	330
November	1st to 10th	Day	9% 8% 39% 29% 12% 2	300
	11th to 20th	Day	7% 13% 38% 27% 13% 3	300
	21st to end	Day	17% 10% 33% 26% 11% 3	291
December	1st to 10th	Day	7% 9% 43% 30% 10% 2	270
	11th to 20th	Day	11% 12% 36% 29% 11% 1	270
	21st to end	Day	14% 19% 42% 19% 5%	297
January	1st to 10th	Night	8% 10% 42% 34% 6%	950
	11th to 20th	Night	9% 14% 37% 33% 7%	950
	21st to end	Night	8% 10% 42% 32% 7%	1045
February	1st to 10th	Night	12% 12% 44% 29% 4 1	770
	11th to 20th	Night	11% 15% 42% 28% 4	744
	21st to end	Night	10% 15% 45% 25% 4	628
March	1st to 10th	Night	8% 12% 47% 29% 4	736
	11th to 20th	Night	16% 11% 42% 26% 6%	570
	21st to end	Night	11% 17% 45% 23% 4	627
April	1st to 10th	Night	8% 15% 48% 27% 3	570
	11th to 20th	Night	11% 18% 45% 23% 3	563
	21st to end	Night	14% 15% 42% 23% 6%	570
May	1st to 10th	Night	12% 13% 46% 25% 5%	570
	11th to 20th	Night	11% 9% 34% 35% 9% 1	561
	21st to end	Night	7% 9% 42% 31% 11% 1	617
June	1st to 10th	Night	6% 5% 42% 33% 13%	570
	11th to 20th	Night	5% 6% 44% 38% 7%	570
	21st to end	Night	6% 2 39% 41% 11%	570
July	1st to 10th	Night	6% 1 24% 45% 22% 2	555
	11th to 20th	Night	5% 1 22% 53% 19% 1	552
	21st to end	Night	5% 1 18% 54% 21% 2	624
August	1st to 10th	Night	5% 1 23% 48% 22% 1	567
	11th to 20th	Night	8% 3 18% 53% 19%	564
	21st to end	Night	4 1 21% 46% 26% 2	627
September	1st to 10th	Night	9% 2 22% 49% 18% 1	570
	11th to 20th	Night	9% 4 31% 42% 13% 1	570
	21st to end	Night	6% 5% 33% 38% 16% 1	570
October	1st to 10th	Night	9% 6% 33% 39% 13%	570
	11th to 20th	Night	8% 8% 42% 35% 5%	673
	21st to end	Night	9% 11% 37% 29% 13% 1	916
November	1st to 10th	Night	8% 8% 39% 35% 9% 1	975
	11th to 20th	Night	7% 13% 42% 32% 7%	1000
	21st to end	Night	9% 13% 34% 34% 9%	986
December	1st to 10th	Night	9% 9% 37% 35% 9%	950
	11th to 20th	Night	13% 11% 41% 31% 4	950
	21st to end	Night	12% 13% 40% 30% 5%	1045

Page generated at 2024-11-24 23:22:20. Version ac07

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