Katepwa Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Katepwa Lake clear sky chart from 2005-11-06 to 2024-04-25.

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	10% 8% 4 8% 7% 4 5% 5% 6% 7% 35%	83088
	Night	8% 9% 4 8% 7% 4 6% 5% 6% 7% 36%	85973
Transparency	Day	47% 6% 15% 23% 9% 1	82801
	Night	47% 5% 15% 22% 10% 1	85840
Seeing	Day	14% 8% 28% 29% 16% 4	15307
	Night	13% 7% 29% 35% 14% 2	24996

By Month

Percentage Cloud Cover NW (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% 14% 6% 13% 11% 6% 7% 5% 8% 7% 16%	2233
	11th to 20th	Day	5% 8% 4 11% 13% 10% 9% 10% 8% 7% 15%	2516
	21st to end	Day	6% 12% 6% 11% 9% 5% 6% 4 4 6% 31%	2794
February	1st to 10th	Day	8% 13% 5% 13% 9% 4 8% 8% 5% 6% 20%	1520
	11th to 20th	Day	7% 9% 7% 10% 8% 5% 8% 8% 7% 6% 25%	1659
	21st to end	Day	6% 8% 5% 9% 12% 6% 8% 7% 8% 8% 23%	1570
March	1st to 10th	Day	9% 11% 6% 12% 9% 4 7% 5% 5% 7% 24%	3130
	11th to 20th	Day	7% 10% 6% 14% 8% 4 5% 4 5% 7% 30%	3250
	21st to end	Day	8% 8% 4 10% 8% 4 5% 5% 6% 8% 33%	4165
April	1st to 10th	Day	8% 8% 3 7% 6% 4 5% 6% 7% 9% 36%	2280
	11th to 20th	Day	15% 15% 4 7% 6% 3 5% 4 4 7% 29%	2321
	21st to end	Day	14% 8% 2 7% 5% 4 5% 5% 6% 8% 37%	2498
May	1st to 10th	Day	11% 7% 3 5% 6% 3 4 5% 6% 9% 41%	2520
	11th to 20th	Day	10% 7% 3 6% 5% 4 4 6% 7% 9% 39%	2478
	21st to end	Day	19% 7% 3 6% 5% 3 6% 5% 6% 7% 33%	2875
June	1st to 10th	Day	16% 5% 2 6% 6% 3 6% 6% 7% 8% 37%	2725
	11th to 20th	Day	19% 6% 3 7% 6% 4 6% 6% 6% 7% 30%	2880
	21st to end	Day	12% 5% 2 5% 6% 3 5% 6% 7% 9% 40%	2880
July	1st to 10th	Day	7% 4 2 4 4 3 5% 5% 5% 10% 50%	2880
	11th to 20th	Day	9% 4 2 5% 4 3 5% 5% 8% 9% 46%	2570
	21st to end	Day	7% 4 1 4 4 4 5% 5% 6% 8% 52%	2742
August	1st to 10th	Day	8% 4 2 5% 5% 3 5% 5% 7% 9% 49%	2507
	11th to 20th	Day	9% 4 2 4 5% 4 4 5% 6% 9% 48%	2477
	21st to end	Day	13% 4 2 4 4 2 4 4 5% 7% 51%	2450
September	1st to 10th	Day	12% 5% 2 5% 4 2 4 5% 4 8% 48%	2160
	11th to 20th	Day	12% 8% 3 6% 5% 3 3 4 5% 8% 43%	2115
	21st to end	Day	14% 6% 3 4 4 2 4 4 4 7% 49%	1980
October	1st to 10th	Day	17% 12% 4 6% 4 3 4 3 6% 7% 36%	1823
	11th to 20th	Day	11% 10% 5% 6% 5% 3 4 4 5% 8% 40%	1685
	21st to end	Day	12% 11% 6% 9% 7% 3 4 5% 5% 6% 32%	1782
November	1st to 10th	Day	16% 14% 5% 8% 9% 4 5% 4 4 5% 27%	1598
	11th to 20th	Day	7% 13% 6% 12% 10% 4 5% 5% 5% 7% 26%	1468
	21st to end	Day	10% 14% 7% 9% 7% 4 5% 5% 5% 6% 28%	1330
December	1st to 10th	Day	7% 12% 5% 11% 13% 6% 7% 7% 6% 5% 21%	1330
	11th to 20th	Day	8% 16% 8% 15% 9% 4 6% 6% 6% 6% 17%	1679
	21st to end	Day	5% 8% 3 6% 6% 3 5% 4 4 5% 49%	2218
January	1st to 10th	Night	5% 15% 6% 12% 10% 4 6% 5% 6% 7% 24%	4693
	11th to 20th	Night	6% 7% 4 14% 14% 9% 10% 7% 6% 6% 18%	4392
	21st to end	Night	6% 12% 4 10% 9% 4 5% 5% 7% 6% 31%	4873
February	1st to 10th	Night	9% 10% 5% 10% 8% 5% 8% 7% 7% 8% 24%	2660
	11th to 20th	Night	4 10% 6% 10% 9% 5% 8% 7% 7% 7% 28%	2424
	21st to end	Night	4 8% 5% 10% 9% 6% 6% 6% 7% 8% 31%	1884
March	1st to 10th	Night	7% 11% 6% 10% 9% 4 6% 4 5% 9% 29%	3734
	11th to 20th	Night	5% 11% 5% 7% 7% 4 6% 6% 5% 8% 36%	3706
	21st to end	Night	6% 8% 4 10% 8% 5% 6% 5% 7% 8% 32%	3477
April	1st to 10th	Night	6% 8% 3 5% 6% 4 5% 4 6% 8% 44%	1900
	11th to 20th	Night	15% 10% 4 7% 5% 3 5% 5% 6% 6% 34%	1809
	21st to end	Night	15% 7% 2 6% 7% 3 6% 5% 6% 6% 36%	1559
May	1st to 10th	Night	11% 6% 2 6% 5% 3 5% 6% 6% 7% 42%	1440
	11th to 20th	Night	13% 5% 2 5% 5% 2 4 5% 6% 8% 45%	1418
	21st to end	Night	18% 5% 2 5% 4 3 5% 5% 6% 9% 39%	1398
June	1st to 10th	Night	13% 5% 2 4 4 3 4 5% 5% 7% 46%	1232
	11th to 20th	Night	17% 6% 3 4 5% 3 7% 5% 5% 6% 39%	1080
	21st to end	Night	11% 5% 2 4 5% 2 4 5% 6% 8% 47%	1080
July	1st to 10th	Night	7% 3 2 3 4 3 6% 5% 7% 8% 54%	1080
	11th to 20th	Night	8% 2 1 3 3 2 5% 4 5% 8% 57%	1384
	21st to end	Night	5% 3 2 3 2 2 3 4 5% 8% 62%	1576
August	1st to 10th	Night	6% 4 1 3 3 2 4 5% 6% 8% 57%	1432
	11th to 20th	Night	8% 3 1 3 4 3 5% 5% 6% 9% 54%	1424
	21st to end	Night	9% 4 2 4 3 2 3 4 5% 9% 56%	1903
September	1st to 10th	Night	10% 5% 2 5% 4 3 4 4 5% 7% 50%	1800
	11th to 20th	Night	12% 6% 2 4 4 3 5% 5% 6% 8% 47%	1845
	21st to end	Night	12% 5% 2 5% 4 2 4 5% 6% 6% 48%	1980
October	1st to 10th	Night	14% 10% 3 5% 4 2 4 4 5% 7% 40%	2134
	11th to 20th	Night	10% 8% 4 5% 4 3 4 4 5% 7% 45%	2256
	21st to end	Night	11% 14% 5% 9% 5% 3 5% 4 5% 7% 33%	2574
November	1st to 10th	Night	16% 13% 5% 9% 7% 3 4 4 4 5% 30%	2476
	11th to 20th	Night	9% 13% 6% 11% 9% 4 6% 5% 5% 5% 28%	2712
	21st to end	Night	9% 12% 6% 10% 8% 4 5% 5% 6% 6% 31%	2850
December	1st to 10th	Night	7% 10% 7% 12% 9% 6% 6% 7% 6% 6% 25%	2850
	11th to 20th	Night	8% 13% 6% 13% 9% 5% 7% 6% 5% 6% 21%	3518
	21st to end	Night	5% 7% 3 8% 7% 3 5% 5% 5% 7% 44%	5420

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	65% 6% 14% 11% 4	2233
	11th to 20th	Day	63% 6% 14% 13% 4	2540
	21st to end	Day	55% 4 11% 24% 5%	2794
February	1st to 10th	Day	62% 6% 13% 13% 6%	1520
	11th to 20th	Day	56% 5% 10% 17% 11%	1668
	21st to end	Day	56% 7% 13% 16% 9%	1570
March	1st to 10th	Day	58% 6% 14% 18% 4	3130
	11th to 20th	Day	54% 6% 17% 18% 5%	3251
	21st to end	Day	47% 6% 14% 19% 13% 1	4165
April	1st to 10th	Day	42% 7% 16% 25% 10%	2280
	11th to 20th	Day	56% 5% 12% 17% 8% 2	2321
	21st to end	Day	45% 5% 18% 24% 8% 1	2498
May	1st to 10th	Day	40% 6% 13% 28% 13% 1	2520
	11th to 20th	Day	40% 6% 12% 28% 13% 1	2482
	21st to end	Day	50% 5% 13% 20% 12% 1	2875
June	1st to 10th	Day	44% 6% 15% 25% 9% 1	2725
	11th to 20th	Day	51% 7% 15% 18% 9%	2880
	21st to end	Day	38% 8% 19% 25% 8%	2880
July	1st to 10th	Day	31% 6% 21% 33% 9%	2801
	11th to 20th	Day	33% 7% 19% 29% 11% 1	2491
	21st to end	Day	29% 6% 17% 36% 11% 1	2590
August	1st to 10th	Day	31% 7% 22% 28% 11% 1	2491
	11th to 20th	Day	32% 6% 23% 31% 7% 1	2477
	21st to end	Day	33% 6% 12% 35% 12% 1	2450
September	1st to 10th	Day	36% 4 15% 31% 13% 1	2160
	11th to 20th	Day	40% 5% 15% 26% 12% 1	2115
	21st to end	Day	36% 4 16% 32% 11% 1	1980
October	1st to 10th	Day	48% 4 15% 24% 7% 1	1823
	11th to 20th	Day	44% 4 13% 30% 10% 1	1685
	21st to end	Day	53% 5% 17% 19% 6%	1782
November	1st to 10th	Day	61% 5% 14% 14% 7%	1598
	11th to 20th	Day	59% 6% 14% 14% 7% 1	1468
	21st to end	Day	59% 5% 15% 16% 5%	1330
December	1st to 10th	Day	63% 5% 11% 14% 6%	1330
	11th to 20th	Day	67% 5% 14% 11% 3	1680
	21st to end	Day	38% 5% 11% 26% 13% 6%	2218
January	1st to 10th	Night	59% 5% 15% 16% 5%	4693
	11th to 20th	Night	65% 5% 14% 12% 4	4430
	21st to end	Night	52% 6% 17% 20% 5%	4873
February	1st to 10th	Night	56% 6% 12% 18% 7% 1	2660
	11th to 20th	Night	52% 6% 13% 19% 10% 1	2425
	21st to end	Night	50% 5% 12% 24% 8%	1884
March	1st to 10th	Night	52% 5% 19% 19% 5%	3734
	11th to 20th	Night	45% 7% 20% 21% 6%	3706
	21st to end	Night	48% 5% 13% 23% 12%	3477
April	1st to 10th	Night	37% 5% 15% 26% 17% 1	1900
	11th to 20th	Night	50% 5% 10% 22% 12% 2	1809
	21st to end	Night	47% 5% 13% 21% 13% 1	1559
May	1st to 10th	Night	39% 4 13% 26% 16% 1	1440
	11th to 20th	Night	37% 6% 12% 27% 17% 1	1418
	21st to end	Night	41% 7% 17% 19% 15% 2	1398
June	1st to 10th	Night	37% 6% 15% 28% 13% 2	1232
	11th to 20th	Night	45% 6% 14% 21% 13% 1	1080
	21st to end	Night	35% 6% 19% 31% 8% 1	1080
July	1st to 10th	Night	27% 7% 21% 32% 13% 1	1050
	11th to 20th	Night	26% 6% 19% 35% 12% 1	1340
	21st to end	Night	20% 5% 19% 38% 16% 2	1488
August	1st to 10th	Night	23% 7% 21% 35% 14% 1	1424
	11th to 20th	Night	27% 5% 21% 35% 11% 1	1424
	21st to end	Night	26% 5% 14% 38% 16% 1	1903
September	1st to 10th	Night	34% 5% 12% 30% 17% 2	1800
	11th to 20th	Night	36% 6% 15% 28% 14% 1	1845
	21st to end	Night	36% 4 14% 30% 14% 1	1980
October	1st to 10th	Night	43% 5% 19% 23% 9% 1	2134
	11th to 20th	Night	40% 4 15% 28% 12% 1	2256
	21st to end	Night	51% 4 13% 23% 7%	2574
November	1st to 10th	Night	57% 4 12% 17% 8% 1	2476
	11th to 20th	Night	57% 5% 17% 15% 6%	2712
	21st to end	Night	54% 6% 17% 18% 4	2850
December	1st to 10th	Night	59% 6% 13% 16% 5% 1	2850
	11th to 20th	Night	63% 6% 12% 14% 5%	3516
	21st to end	Night	39% 6% 11% 23% 17% 5%	5420

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	13% 10% 29% 30% 13% 5%	228
	11th to 20th	Day	10% 6% 33% 34% 16% 1	270
	21st to end	Day	16% 7% 30% 28% 17% 1	297
February	1st to 10th	Day	14% 11% 28% 32% 14% 1	270
	11th to 20th	Day	10% 8% 31% 32% 15% 4	270
	21st to end	Day	9% 4 24% 41% 17% 5%	225
March	1st to 10th	Day	13% 6% 34% 30% 14% 3	270
	11th to 20th	Day	12% 10% 27% 30% 18% 4	308
	21st to end	Day	16% 9% 31% 27% 14% 3	506
April	1st to 10th	Day	10% 12% 38% 29% 9% 2	460
	11th to 20th	Day	21% 13% 29% 25% 10% 2	519
	21st to end	Day	15% 9% 27% 31% 17%	622
May	1st to 10th	Day	13% 8% 29% 31% 16% 3	603
	11th to 20th	Day	14% 7% 28% 25% 18% 7%	625
	21st to end	Day	17% 5% 26% 27% 17% 8%	679
June	1st to 10th	Day	14% 10% 27% 26% 16% 6%	630
	11th to 20th	Day	17% 12% 29% 25% 12% 4	630
	21st to end	Day	13% 7% 23% 31% 20% 6%	630
July	1st to 10th	Day	7% 5% 25% 33% 24% 5%	621
	11th to 20th	Day	9% 7% 29% 30% 20% 6%	618
	21st to end	Day	7% 6% 27% 32% 20% 8%	684
August	1st to 10th	Day	9% 6% 20% 36% 23% 6%	626
	11th to 20th	Day	8% 5% 21% 33% 25% 8%	615
	21st to end	Day	13% 5% 21% 35% 19% 6%	555
September	1st to 10th	Day	14% 9% 36% 23% 14% 4	450
	11th to 20th	Day	20% 7% 29% 26% 14% 4	405
	21st to end	Day	16% 9% 30% 29% 13% 3	270
October	1st to 10th	Day	22% 10% 24% 20% 21% 3	270
	11th to 20th	Day	18% 11% 29% 26% 11% 4	270
	21st to end	Day	15% 12% 33% 27% 10% 2	297
November	1st to 10th	Day	23% 8% 28% 26% 10% 4	270
	11th to 20th	Day	15% 10% 37% 29% 9%	270
	21st to end	Day	16% 9% 35% 31% 9% 1	270
December	1st to 10th	Day	12% 5% 33% 31% 14% 4	270
	11th to 20th	Day	14% 8% 45% 26% 6% 3	270
	21st to end	Day	13% 5% 32% 30% 16% 4	234
January	1st to 10th	Night	10% 10% 31% 34% 13% 1	950
	11th to 20th	Night	15% 11% 31% 33% 9% 1	950
	21st to end	Night	13% 11% 33% 33% 10% 1	1045
February	1st to 10th	Night	14% 7% 30% 32% 15% 2	950
	11th to 20th	Night	9% 7% 32% 38% 12% 3	768
	21st to end	Night	6% 5% 24% 41% 20% 4	628
March	1st to 10th	Night	13% 7% 29% 36% 14% 2	760
	11th to 20th	Night	10% 6% 32% 36% 16% 1	755
	21st to end	Night	14% 5% 28% 36% 16% 2	627
April	1st to 10th	Night	11% 8% 32% 35% 14% 1	570
	11th to 20th	Night	20% 8% 29% 34% 9% 1	563
	21st to end	Night	18% 6% 31% 34% 10% 1	555
May	1st to 10th	Night	13% 6% 29% 36% 16% 1	540
	11th to 20th	Night	16% 5% 26% 34% 17% 2	531
	21st to end	Night	20% 5% 24% 31% 17% 2	584
June	1st to 10th	Night	16% 5% 27% 35% 16% 2	512
	11th to 20th	Night	21% 6% 27% 34% 12% 1	360
	21st to end	Night	14% 4 24% 38% 19% 1	360
July	1st to 10th	Night	9% 3 24% 42% 22% 1	350
	11th to 20th	Night	10% 3 26% 41% 19% 1	492
	21st to end	Night	6% 4 22% 42% 23% 3	591
August	1st to 10th	Night	8% 3 22% 43% 22% 3	537
	11th to 20th	Night	9% 2 16% 45% 26% 1	534
	21st to end	Night	10% 5% 24% 40% 20% 1	594
September	1st to 10th	Night	12% 5% 26% 35% 20% 2	540
	11th to 20th	Night	14% 6% 23% 42% 15% 1	540
	21st to end	Night	13% 6% 29% 38% 13% 1	540
October	1st to 10th	Night	20% 7% 21% 35% 16% 1	694
	11th to 20th	Night	14% 8% 27% 36% 14% 1	816
	21st to end	Night	17% 10% 30% 34% 8% 1	990
November	1st to 10th	Night	20% 10% 30% 31% 9% 1	925
	11th to 20th	Night	15% 10% 35% 28% 10% 2	950
	21st to end	Night	14% 10% 36% 33% 6% 1	950
December	1st to 10th	Night	12% 7% 34% 31% 13% 3	950
	11th to 20th	Night	12% 11% 33% 32% 11% 2	950
	21st to end	Night	12% 6% 30% 34% 15% 3	1045

Page generated at 2024-04-22 07:25:47. Version ac07

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