Glacial Lakes State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Glacial Lakes State Park clear sky chart from 2005-11-06 to 2024-11-05.

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	12% 8% 3 8% 5% 5% 5% 4 6% 7% 38%	101629
	Night	11% 9% 4 8% 5% 5% 5% 4 5% 7% 38%	97509
Transparency	Day	43% 6% 14% 25% 11% 1	105210
	Night	43% 5% 13% 25% 12% 1	102073
Seeing	Day	15% 10% 31% 28% 14% 3	16052
	Night	14% 9% 33% 33% 10% 1	25929

By Month

Percentage Cloud Cover SE (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	11% 15% 3 14% 11% 8% 6% 4 6% 5% 18%	2218
	11th to 20th	Day	5% 9% 6% 13% 8% 8% 10% 6% 9% 7% 19%	2477
	21st to end	Day	6% 13% 10% 17% 9% 7% 6% 4 6% 6% 17%	3135
February	1st to 10th	Day	8% 12% 5% 10% 6% 6% 7% 4 7% 8% 27%	1710
	11th to 20th	Day	6% 11% 4 10% 8% 8% 6% 5% 8% 6% 28%	1664
	21st to end	Day	8% 14% 4 11% 7% 7% 5% 5% 8% 6% 25%	1479
March	1st to 10th	Day	12% 12% 4 10% 6% 5% 5% 3 4 5% 34%	3367
	11th to 20th	Day	9% 11% 3 8% 5% 4 5% 3 5% 8% 39%	3480
	21st to end	Day	21% 14% 4 12% 8% 5% 4 3 4 6% 18%	3814
April	1st to 10th	Day	17% 9% 3 7% 3 4 5% 3 6% 8% 35%	2214
	11th to 20th	Day	19% 12% 3 8% 4 4 4 3 5% 6% 32%	2410
	21st to end	Day	23% 10% 3 6% 4 4 4 3 4 5% 33%	2470
May	1st to 10th	Day	17% 7% 2 7% 4 5% 4 3 5% 7% 39%	4082
	11th to 20th	Day	14% 6% 2 6% 4 4 3 4 6% 7% 45%	4392
	21st to end	Day	17% 6% 2 6% 4 4 4 4 6% 9% 36%	4824
June	1st to 10th	Day	11% 5% 2 6% 4 4 4 4 7% 8% 44%	2813
	11th to 20th	Day	14% 6% 3 6% 5% 5% 4 4 6% 7% 39%	2850
	21st to end	Day	9% 5% 2 5% 4 3 5% 5% 7% 9% 45%	2850
July	1st to 10th	Day	9% 4 1 5% 4 5% 6% 5% 8% 10% 41%	4750
	11th to 20th	Day	4 3 1 3 2 3 4 3 6% 9% 60%	4750
	21st to end	Day	5% 4 2 6% 4 5% 4 5% 7% 9% 50%	4541
August	1st to 10th	Day	12% 5% 2 5% 4 3 4 4 6% 8% 46%	4104
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 6% 10% 41%	4041
	21st to end	Day	9% 5% 2 5% 4 4 5% 4 5% 8% 49%	4508
September	1st to 10th	Day	11% 4 1 5% 3 3 4 3 5% 8% 53%	2280
	11th to 20th	Day	11% 5% 2 5% 3 4 5% 4 6% 7% 48%	2114
	21st to end	Day	15% 5% 2 4 3 3 3 3 5% 7% 49%	2085
October	1st to 10th	Day	16% 9% 2 5% 4 4 2 4 6% 7% 42%	1900
	11th to 20th	Day	15% 12% 2 5% 3 3 4 3 4 6% 42%	1900
	21st to end	Day	16% 11% 3 7% 5% 3 4 3 5% 6% 37%	2027
November	1st to 10th	Day	13% 12% 3 8% 6% 3 3 3 6% 7% 36%	1600
	11th to 20th	Day	11% 12% 5% 14% 8% 5% 5% 4 3 6% 28%	1520
	21st to end	Day	12% 11% 4 10% 7% 5% 5% 4 6% 6% 31%	1520
December	1st to 10th	Day	8% 12% 5% 13% 9% 7% 7% 4 6% 5% 24%	1520
	11th to 20th	Day	9% 13% 7% 13% 7% 5% 5% 3 4 6% 26%	1778
	21st to end	Day	21% 14% 5% 15% 7% 4 3 3 4 6% 19%	2442
January	1st to 10th	Night	8% 12% 5% 15% 11% 7% 5% 4 6% 6% 21%	4737
	11th to 20th	Night	5% 10% 5% 14% 9% 10% 11% 7% 7% 6% 17%	4490
	21st to end	Night	7% 16% 11% 13% 6% 5% 5% 4 5% 6% 22%	4532
February	1st to 10th	Night	6% 11% 4 10% 7% 6% 6% 4 7% 8% 31%	2470
	11th to 20th	Night	6% 10% 4 8% 6% 6% 7% 5% 7% 7% 36%	2403
	21st to end	Night	11% 9% 4 9% 5% 5% 6% 4 6% 7% 33%	1989
March	1st to 10th	Night	8% 8% 3 7% 5% 4 4 4 6% 7% 44%	3488
	11th to 20th	Night	9% 8% 3 7% 5% 4 5% 4 7% 7% 40%	3480
	21st to end	Night	22% 13% 4 10% 5% 4 3 3 5% 5% 26%	3817
April	1st to 10th	Night	15% 10% 3 6% 3 4 4 3 5% 6% 41%	1965
	11th to 20th	Night	18% 9% 4 7% 4 4 4 3 4 6% 37%	1718
	21st to end	Night	18% 10% 3 6% 3 3 5% 3 4 5% 39%	1710
May	1st to 10th	Night	17% 7% 2 6% 4 3 4 3 4 6% 44%	2823
	11th to 20th	Night	12% 6% 2 7% 3 5% 4 4 5% 6% 46%	2511
	21st to end	Night	16% 7% 3 6% 4 4 5% 4 6% 7% 40%	2743
June	1st to 10th	Night	10% 5% 2 4 4 3 4 4 5% 9% 49%	1363
	11th to 20th	Night	11% 4 2 5% 4 4 5% 3 6% 8% 48%	1330
	21st to end	Night	8% 5% 2 4 3 3 3 3 6% 7% 57%	1330
July	1st to 10th	Night	9% 6% 3 6% 4 4 4 5% 8% 9% 43%	2220
	11th to 20th	Night	4 2 1 3 2 3 4 3 4 7% 66%	2220
	21st to end	Night	4 4 2 4 3 3 4 4 7% 9% 55%	3017
August	1st to 10th	Night	10% 6% 2 5% 3 3 4 3 6% 8% 50%	2836
	11th to 20th	Night	12% 4 2 5% 3 4 3 4 5% 8% 51%	2798
	21st to end	Night	9% 4 2 5% 4 3 3 4 5% 8% 53%	3157
September	1st to 10th	Night	8% 5% 1 4 2 2 3 3 6% 7% 59%	1900
	11th to 20th	Night	10% 5% 2 5% 4 4 4 4 5% 6% 53%	2062
	21st to end	Night	11% 5% 2 5% 3 3 3 3 4 6% 54%	2090
October	1st to 10th	Night	12% 7% 2 6% 4 3 4 3 4 7% 47%	2265
	11th to 20th	Night	14% 9% 2 6% 4 3 3 4 5% 6% 44%	2280
	21st to end	Night	16% 11% 3 8% 4 3 4 3 5% 6% 38%	2570
November	1st to 10th	Night	12% 9% 3 7% 5% 5% 5% 4 5% 6% 40%	2579
	11th to 20th	Night	11% 12% 5% 11% 6% 4 4 3 4 5% 36%	2660
	21st to end	Night	10% 10% 3 9% 6% 4 4 3 5% 7% 37%	2660
December	1st to 10th	Night	8% 12% 5% 11% 8% 6% 5% 3 6% 7% 29%	2660
	11th to 20th	Night	11% 11% 4 11% 7% 6% 6% 4 5% 7% 27%	3411
	21st to end	Night	19% 15% 5% 13% 7% 5% 5% 4 4 5% 18%	5225

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	67% 5% 10% 14% 4	2219
	11th to 20th	Day	59% 5% 13% 19% 4	2477
	21st to end	Day	66% 6% 11% 13% 4	3135
February	1st to 10th	Day	54% 6% 11% 20% 8%	1710
	11th to 20th	Day	53% 7% 13% 20% 5% 1	1673
	21st to end	Day	56% 6% 11% 18% 8%	1479
March	1st to 10th	Day	52% 5% 11% 25% 6% 1	3367
	11th to 20th	Day	43% 5% 12% 28% 9% 2	3480
	21st to end	Day	67% 5% 10% 15% 3	3814
April	1st to 10th	Day	46% 6% 12% 23% 12% 1	2214
	11th to 20th	Day	52% 5% 11% 18% 13% 1	2410
	21st to end	Day	53% 5% 11% 22% 8% 1	2470
May	1st to 10th	Day	42% 7% 12% 25% 14%	4120
	11th to 20th	Day	38% 6% 10% 30% 13% 3	4396
	21st to end	Day	42% 7% 14% 27% 9% 1	4837
June	1st to 10th	Day	36% 6% 16% 29% 11% 1	2813
	11th to 20th	Day	42% 8% 14% 21% 14% 1	2850
	21st to end	Day	32% 8% 20% 28% 12% 1	2850
July	1st to 10th	Day	34% 10% 20% 24% 13%	4676
	11th to 20th	Day	20% 6% 17% 38% 17% 2	4669
	21st to end	Day	28% 8% 18% 32% 14% 1	4398
August	1st to 10th	Day	35% 5% 14% 33% 12% 2	4090
	11th to 20th	Day	37% 7% 16% 32% 7% 1	4080
	21st to end	Day	32% 7% 17% 30% 12% 2	4507
September	1st to 10th	Day	29% 6% 16% 37% 12% 1	2280
	11th to 20th	Day	33% 6% 18% 31% 10%	2114
	21st to end	Day	34% 6% 14% 32% 13% 2	2085
October	1st to 10th	Day	32% 3 8% 32% 23% 1	3160
	11th to 20th	Day	37% 4 12% 23% 22% 1	3140
	21st to end	Day	47% 4 14% 26% 9%	3320
November	1st to 10th	Day	46% 5% 13% 22% 12% 3	1600
	11th to 20th	Day	58% 5% 12% 17% 8%	1520
	21st to end	Day	50% 5% 18% 19% 6% 2	1520
December	1st to 10th	Day	57% 6% 16% 15% 6%	1520
	11th to 20th	Day	59% 5% 16% 17% 4	1775
	21st to end	Day	68% 4 10% 13% 5%	2442
January	1st to 10th	Night	61% 7% 11% 17% 4	4737
	11th to 20th	Night	63% 7% 11% 14% 5%	4490
	21st to end	Night	60% 6% 12% 16% 6%	4532
February	1st to 10th	Night	49% 6% 13% 20% 11% 1	2470
	11th to 20th	Night	45% 6% 14% 23% 11% 1	2404
	21st to end	Night	48% 7% 13% 19% 11% 2	1989
March	1st to 10th	Night	37% 5% 15% 28% 13% 2	3488
	11th to 20th	Night	39% 6% 12% 32% 12%	3480
	21st to end	Night	59% 5% 9% 20% 6% 1	3817
April	1st to 10th	Night	43% 5% 13% 27% 11% 2	1965
	11th to 20th	Night	49% 4 6% 24% 15% 2	1718
	21st to end	Night	47% 4 11% 23% 13% 2	1710
May	1st to 10th	Night	40% 5% 11% 28% 14% 3	2850
	11th to 20th	Night	37% 6% 10% 24% 20% 3	2512
	21st to end	Night	41% 6% 14% 25% 12% 2	2751
June	1st to 10th	Night	32% 5% 16% 30% 15% 2	1363
	11th to 20th	Night	32% 7% 17% 25% 17% 3	1330
	21st to end	Night	27% 4 18% 31% 18% 2	1330
July	1st to 10th	Night	35% 7% 20% 23% 15% 1	2185
	11th to 20th	Night	18% 4 14% 44% 18% 3	2178
	21st to end	Night	24% 7% 19% 34% 14% 2	2922
August	1st to 10th	Night	33% 5% 15% 28% 16% 4	2826
	11th to 20th	Night	32% 5% 17% 33% 12% 1	2825
	21st to end	Night	28% 6% 18% 31% 14% 2	3157
September	1st to 10th	Night	25% 5% 17% 34% 18% 1	1900
	11th to 20th	Night	31% 6% 15% 31% 17%	2062
	21st to end	Night	32% 4 12% 33% 18% 1	2090
October	1st to 10th	Night	24% 3 7% 36% 25% 4	3785
	11th to 20th	Night	33% 4 12% 28% 20% 2	3779
	21st to end	Night	41% 5% 15% 25% 13% 1	4231
November	1st to 10th	Night	42% 5% 14% 23% 13% 2	2579
	11th to 20th	Night	50% 5% 14% 20% 11% 1	2660
	21st to end	Night	45% 6% 18% 22% 8% 2	2660
December	1st to 10th	Night	53% 5% 16% 19% 7%	2660
	11th to 20th	Night	55% 6% 17% 17% 5% 1	3413
	21st to end	Night	67% 6% 10% 13% 4	5225

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	17% 8% 34% 29% 9% 3	270
	11th to 20th	Day	13% 12% 34% 31% 9% 1	270
	21st to end	Day	13% 12% 36% 24% 13% 2	297
February	1st to 10th	Day	12% 15% 40% 30% 3	270
	11th to 20th	Day	12% 16% 39% 27% 7%	270
	21st to end	Day	13% 14% 40% 26% 7%	225
March	1st to 10th	Day	15% 16% 39% 23% 7%	270
	11th to 20th	Day	19% 7% 37% 24% 10% 2	270
	21st to end	Day	24% 12% 26% 25% 10% 4	297
April	1st to 10th	Day	26% 14% 33% 21% 7%	394
	11th to 20th	Day	27% 15% 25% 23% 9% 1	608
	21st to end	Day	25% 11% 32% 20% 11% 1	650
May	1st to 10th	Day	19% 13% 35% 24% 9% 1	653
	11th to 20th	Day	19% 13% 28% 27% 12% 2	675
	21st to end	Day	17% 8% 32% 27% 13% 2	734
June	1st to 10th	Day	10% 9% 24% 34% 20% 3	680
	11th to 20th	Day	14% 9% 37% 27% 11% 2	680
	21st to end	Day	13% 6% 34% 30% 15% 3	680
July	1st to 10th	Day	6% 4 25% 33% 26% 6%	671
	11th to 20th	Day	7% 7% 26% 35% 19% 6%	668
	21st to end	Day	5% 3 25% 35% 25% 6%	739
August	1st to 10th	Day	10% 3 23% 33% 26% 5%	676
	11th to 20th	Day	12% 4 22% 32% 23% 6%	665
	21st to end	Day	10% 6% 26% 32% 21% 4	737
September	1st to 10th	Day	11% 8% 28% 32% 17% 3	490
	11th to 20th	Day	10% 4 34% 33% 15% 4	324
	21st to end	Day	17% 14% 29% 25% 13% 2	300
October	1st to 10th	Day	18% 12% 29% 26% 11% 4	300
	11th to 20th	Day	16% 17% 38% 20% 7% 2	300
	21st to end	Day	22% 17% 35% 18% 6% 1	330
November	1st to 10th	Day	24% 12% 26% 30% 7% 1	282
	11th to 20th	Day	17% 17% 41% 21% 4	270
	21st to end	Day	19% 19% 34% 23% 4	270
December	1st to 10th	Day	10% 10% 44% 26% 10%	270
	11th to 20th	Day	16% 13% 43% 23% 5%	270
	21st to end	Day	28% 11% 34% 23% 5%	297
January	1st to 10th	Night	11% 9% 40% 30% 8% 2	950
	11th to 20th	Night	12% 12% 37% 31% 8% 1	950
	21st to end	Night	14% 11% 37% 31% 7%	1045
February	1st to 10th	Night	10% 10% 38% 33% 9% 1	950
	11th to 20th	Night	11% 11% 41% 28% 8% 1	929
	21st to end	Night	15% 11% 32% 31% 10% 1	733
March	1st to 10th	Night	15% 11% 36% 30% 7% 1	617
	11th to 20th	Night	17% 10% 37% 30% 5% 1	570
	21st to end	Night	18% 10% 30% 29% 12% 1	627
April	1st to 10th	Night	18% 11% 38% 28% 4	570
	11th to 20th	Night	22% 12% 31% 27% 8% 1	563
	21st to end	Night	21% 10% 32% 28% 8% 1	570
May	1st to 10th	Night	19% 11% 32% 30% 8% 1	570
	11th to 20th	Night	15% 8% 33% 33% 11%	561
	21st to end	Night	14% 10% 29% 38% 9%	617
June	1st to 10th	Night	12% 7% 26% 38% 16% 1	570
	11th to 20th	Night	11% 4 34% 44% 7%	570
	21st to end	Night	9% 4 26% 47% 14% 1	570
July	1st to 10th	Night	5% 3 21% 45% 25% 2	555
	11th to 20th	Night	5% 3 25% 47% 17% 2	552
	21st to end	Night	6% 2 22% 46% 21% 3	624
August	1st to 10th	Night	8% 2 22% 46% 21% 1	567
	11th to 20th	Night	10% 3 22% 39% 23% 2	564
	21st to end	Night	7% 4 26% 39% 22% 1	627
September	1st to 10th	Night	11% 4 26% 41% 16% 2	570
	11th to 20th	Night	11% 5% 29% 37% 16% 1	570
	21st to end	Night	12% 7% 35% 32% 12% 1	570
October	1st to 10th	Night	17% 10% 35% 29% 10%	745
	11th to 20th	Night	18% 11% 32% 30% 8% 1	760
	21st to end	Night	20% 12% 34% 28% 5%	898
November	1st to 10th	Night	16% 11% 32% 32% 9%	950
	11th to 20th	Night	16% 12% 37% 25% 9% 1	950
	21st to end	Night	14% 13% 39% 27% 7%	950
December	1st to 10th	Night	13% 11% 37% 31% 8% 1	950
	11th to 20th	Night	17% 10% 35% 31% 6% 1	950
	21st to end	Night	23% 11% 35% 25% 5% 1	1045

Page generated at 2024-11-03 01:11:07. Version ac07

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