Getchell Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Getchell Mountain clear sky chart from 2005-11-06 to 2024-11-12.

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	18% 9% 3 7% 5% 4 4 4 5% 7% 33%	101447
	Night	19% 9% 3 7% 5% 4 4 4 5% 6% 34%	97779
Transparency	Day	48% 6% 12% 21% 12% 1	104966
	Night	48% 6% 12% 21% 11% 1	102350
Seeing	Day	27% 16% 31% 18% 6% 1	16003
	Night	25% 15% 32% 22% 6%	24108

By Month

Percentage Cloud Cover NE (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	14% 12% 3 9% 4 4 4 5% 5% 5% 34%	2366
	11th to 20th	Day	15% 11% 3 8% 5% 4 4 2 3 5% 41%	2520
	21st to end	Day	13% 10% 5% 10% 6% 5% 5% 4 5% 6% 32%	2843
February	1st to 10th	Day	15% 12% 4 9% 6% 5% 5% 3 5% 6% 29%	1710
	11th to 20th	Day	14% 13% 5% 9% 5% 5% 5% 3 5% 6% 31%	1710
	21st to end	Day	12% 12% 4 8% 6% 4 5% 4 4 7% 33%	1570
March	1st to 10th	Day	24% 14% 3 7% 4 4 4 3 4 5% 29%	3179
	11th to 20th	Day	18% 16% 4 10% 6% 5% 4 3 5% 5% 23%	3480
	21st to end	Day	26% 11% 4 8% 4 3 3 3 4 6% 26%	3816
April	1st to 10th	Day	21% 14% 3 8% 5% 4 4 3 5% 6% 28%	2241
	11th to 20th	Day	20% 10% 3 6% 5% 3 4 3 5% 6% 34%	2442
	21st to end	Day	22% 12% 3 7% 4 4 3 3 4 5% 33%	2470
May	1st to 10th	Day	20% 10% 2 6% 5% 4 5% 3 5% 6% 33%	4106
	11th to 20th	Day	19% 9% 3 7% 5% 5% 5% 5% 6% 7% 29%	4081
	21st to end	Day	16% 7% 2 6% 5% 5% 6% 4 6% 8% 33%	5137
June	1st to 10th	Day	24% 8% 3 8% 4 5% 4 3 6% 7% 28%	2850
	11th to 20th	Day	20% 7% 2 5% 5% 4 4 4 6% 8% 36%	2850
	21st to end	Day	25% 8% 3 7% 5% 4 5% 4 5% 6% 27%	2850
July	1st to 10th	Day	14% 7% 2 7% 5% 6% 6% 5% 8% 8% 33%	4760
	11th to 20th	Day	18% 6% 2 7% 5% 5% 5% 4 7% 8% 36%	4486
	21st to end	Day	17% 7% 3 6% 5% 4 5% 4 5% 8% 36%	4726
August	1st to 10th	Day	19% 8% 3 8% 6% 5% 5% 4 6% 7% 31%	4105
	11th to 20th	Day	16% 9% 3 8% 5% 5% 5% 5% 6% 8% 30%	4045
	21st to end	Day	13% 6% 2 7% 5% 4 5% 4 5% 8% 41%	4532
September	1st to 10th	Day	11% 5% 2 6% 4 4 3 3 5% 8% 47%	2215
	11th to 20th	Day	15% 7% 2 4 3 3 3 3 3 5% 50%	2090
	21st to end	Day	18% 7% 2 6% 4 3 4 3 4 7% 43%	2090
October	1st to 10th	Day	18% 8% 3 7% 5% 4 3 3 5% 6% 39%	2000
	11th to 20th	Day	21% 7% 2 6% 4 5% 4 3 5% 6% 38%	1900
	21st to end	Day	21% 11% 3 8% 4 5% 3 3 4 6% 33%	1893
November	1st to 10th	Day	20% 8% 2 7% 4 4 5% 4 4 6% 38%	1761
	11th to 20th	Day	20% 8% 2 5% 4 3 5% 4 4 8% 37%	1586
	21st to end	Day	21% 9% 3 7% 5% 4 4 4 5% 6% 33%	1520
December	1st to 10th	Day	23% 12% 3 7% 6% 4 5% 4 4 5% 28%	1418
	11th to 20th	Day	22% 12% 3 7% 5% 4 4 4 4 5% 30%	1668
	21st to end	Day	23% 11% 3 8% 5% 4 4 3 4 5% 30%	2431
January	1st to 10th	Night	13% 11% 4 9% 5% 5% 4 3 5% 6% 34%	4582
	11th to 20th	Night	14% 9% 3 9% 5% 5% 5% 4 5% 6% 35%	4440
	21st to end	Night	13% 11% 4 10% 6% 5% 5% 5% 5% 6% 30%	4811
February	1st to 10th	Night	15% 11% 4 8% 6% 5% 6% 4 6% 6% 29%	2470
	11th to 20th	Night	13% 12% 3 10% 6% 5% 4 4 5% 7% 31%	2353
	21st to end	Night	15% 12% 4 8% 5% 4 4 3 4 5% 36%	1884
March	1st to 10th	Night	26% 14% 3 6% 4 5% 4 3 4 4 27%	3661
	11th to 20th	Night	18% 15% 3 8% 6% 6% 5% 3 5% 6% 24%	3479
	21st to end	Night	27% 11% 3 7% 4 4 4 4 6% 6% 25%	3816
April	1st to 10th	Night	21% 13% 3 7% 5% 2 3 3 4 6% 33%	1934
	11th to 20th	Night	21% 10% 2 6% 5% 5% 4 3 5% 7% 33%	1688
	21st to end	Night	25% 10% 3 6% 5% 4 4 3 5% 6% 30%	1710
May	1st to 10th	Night	23% 7% 2 6% 4 3 3 3 6% 7% 35%	2834
	11th to 20th	Night	17% 9% 3 8% 6% 6% 5% 4 6% 7% 28%	2799
	21st to end	Night	15% 8% 2 6% 5% 5% 4 4 5% 7% 38%	2477
June	1st to 10th	Night	23% 9% 3 7% 5% 4 4 4 5% 7% 28%	1330
	11th to 20th	Night	16% 9% 2 7% 5% 4 3 4 5% 8% 36%	1330
	21st to end	Night	26% 7% 3 7% 6% 4 4 3 5% 7% 29%	1330
July	1st to 10th	Night	13% 6% 2 6% 5% 4 5% 6% 7% 9% 37%	2210
	11th to 20th	Night	19% 8% 3 6% 4 4 4 4 7% 6% 34%	2472
	21st to end	Night	14% 8% 2 6% 4 4 4 4 7% 8% 38%	2796
August	1st to 10th	Night	21% 6% 4 8% 5% 5% 6% 4 5% 7% 29%	2825
	11th to 20th	Night	15% 9% 3 8% 5% 6% 5% 5% 6% 8% 31%	2782
	21st to end	Night	12% 7% 2 7% 4 4 3 3 5% 7% 46%	3124
September	1st to 10th	Night	14% 5% 1 5% 3 3 5% 4 5% 6% 48%	1960
	11th to 20th	Night	16% 6% 2 4 3 3 3 3 5% 6% 49%	2090
	21st to end	Night	18% 6% 2 5% 3 3 4 3 5% 7% 44%	2090
October	1st to 10th	Night	19% 6% 2 5% 3 3 3 4 5% 6% 42%	2179
	11th to 20th	Night	18% 7% 2 7% 5% 4 4 4 5% 6% 39%	2280
	21st to end	Night	22% 10% 2 7% 4 4 4 3 5% 5% 34%	2703
November	1st to 10th	Night	18% 7% 2 7% 4 4 4 4 5% 7% 38%	2537
	11th to 20th	Night	19% 8% 2 6% 4 5% 4 4 5% 5% 37%	2617
	21st to end	Night	19% 10% 3 7% 4 3 4 4 5% 6% 34%	2660
December	1st to 10th	Night	24% 11% 4 7% 5% 4 4 3 5% 5% 30%	2759
	11th to 20th	Night	25% 9% 3 5% 5% 5% 3 3 4 5% 32%	3531
	21st to end	Night	23% 11% 3 7% 4 3 3 3 4 5% 33%	5236

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	50% 5% 15% 22% 8%	2367
	11th to 20th	Day	46% 5% 9% 26% 13% 2	2520
	21st to end	Day	50% 7% 12% 16% 14% 1	2843
February	1st to 10th	Day	54% 6% 11% 17% 11% 2	1710
	11th to 20th	Day	53% 5% 10% 18% 13% 1	1718
	21st to end	Day	49% 5% 10% 20% 11% 5%	1570
March	1st to 10th	Day	58% 4 8% 15% 12% 3	3183
	11th to 20th	Day	58% 7% 11% 11% 11% 1	3480
	21st to end	Day	58% 3 7% 15% 13% 3	3816
April	1st to 10th	Day	57% 5% 9% 14% 12% 3	2241
	11th to 20th	Day	49% 5% 10% 21% 15% 1	2442
	21st to end	Day	52% 5% 8% 17% 14% 4	2470
May	1st to 10th	Day	50% 6% 11% 21% 9% 2	4120
	11th to 20th	Day	50% 8% 13% 20% 7% 1	4085
	21st to end	Day	44% 8% 15% 16% 15% 1	5137
June	1st to 10th	Day	53% 6% 12% 18% 10% 1	2850
	11th to 20th	Day	45% 6% 11% 21% 15% 2	2850
	21st to end	Day	55% 8% 11% 16% 9% 1	2850
July	1st to 10th	Day	44% 7% 14% 23% 11% 1	4685
	11th to 20th	Day	44% 7% 14% 24% 10% 1	4409
	21st to end	Day	45% 7% 11% 25% 10% 1	4575
August	1st to 10th	Day	50% 7% 12% 24% 6%	4092
	11th to 20th	Day	48% 8% 15% 21% 7%	4084
	21st to end	Day	37% 6% 13% 25% 18% 1	4532
September	1st to 10th	Day	34% 7% 12% 29% 17% 1	2215
	11th to 20th	Day	37% 4 9% 28% 19% 3	2090
	21st to end	Day	40% 5% 9% 28% 17% 1	2090
October	1st to 10th	Day	53% 5% 9% 24% 9%	3325
	11th to 20th	Day	40% 5% 10% 31% 14%	3140
	21st to end	Day	37% 4 17% 23% 19%	3093
November	1st to 10th	Day	46% 6% 13% 19% 14% 1	1761
	11th to 20th	Day	45% 6% 13% 21% 14% 2	1586
	21st to end	Day	50% 6% 15% 21% 7%	1520
December	1st to 10th	Day	57% 7% 10% 17% 8% 1	1418
	11th to 20th	Day	56% 5% 10% 18% 10% 1	1668
	21st to end	Day	55% 6% 10% 17% 9% 3	2431
January	1st to 10th	Night	49% 6% 14% 22% 8% 1	4582
	11th to 20th	Night	48% 6% 12% 22% 11% 1	4440
	21st to end	Night	51% 6% 12% 19% 11% 1	4811
February	1st to 10th	Night	51% 6% 13% 18% 10% 2	2470
	11th to 20th	Night	52% 5% 10% 18% 13% 1	2356
	21st to end	Night	50% 4 8% 20% 15% 3	1884
March	1st to 10th	Night	61% 4 7% 16% 10% 2	3670
	11th to 20th	Night	57% 7% 11% 15% 9% 1	3480
	21st to end	Night	59% 4 7% 16% 12% 2	3816
April	1st to 10th	Night	53% 4 9% 15% 16% 4	1934
	11th to 20th	Night	49% 6% 9% 19% 15% 2	1688
	21st to end	Night	54% 6% 10% 14% 14% 3	1710
May	1st to 10th	Night	46% 8% 16% 21% 9% 1	2840
	11th to 20th	Night	50% 10% 14% 19% 7% 1	2800
	21st to end	Night	42% 9% 17% 21% 10% 1	2478
June	1st to 10th	Night	53% 7% 12% 20% 8% 1	1330
	11th to 20th	Night	46% 6% 13% 22% 12% 2	1330
	21st to end	Night	55% 7% 10% 18% 9% 2	1330
July	1st to 10th	Night	41% 8% 15% 23% 12%	2175
	11th to 20th	Night	48% 7% 12% 26% 8%	2426
	21st to end	Night	41% 9% 16% 23% 11% 1	2707
August	1st to 10th	Night	54% 8% 13% 19% 7%	2813
	11th to 20th	Night	48% 8% 17% 19% 7%	2809
	21st to end	Night	36% 8% 15% 23% 17% 1	3124
September	1st to 10th	Night	34% 7% 13% 30% 15% 1	1960
	11th to 20th	Night	36% 5% 13% 27% 18% 1	2090
	21st to end	Night	40% 6% 10% 28% 15% 1	2090
October	1st to 10th	Night	44% 5% 12% 26% 12% 1	3634
	11th to 20th	Night	36% 6% 12% 30% 16%	3779
	21st to end	Night	40% 4 14% 25% 14% 1	4453
November	1st to 10th	Night	44% 7% 13% 24% 12% 1	2537
	11th to 20th	Night	46% 6% 12% 22% 13% 1	2617
	21st to end	Night	49% 6% 14% 19% 10% 1	2660
December	1st to 10th	Night	56% 5% 11% 19% 9%	2759
	11th to 20th	Night	53% 5% 11% 17% 14% 1	3532
	21st to end	Night	53% 5% 11% 18% 9% 3	5236

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	38% 16% 31% 14% 2	180
	11th to 20th	Day	35% 21% 34% 6% 3 1	180
	21st to end	Day	24% 21% 34% 17% 4	243
February	1st to 10th	Day	25% 18% 35% 18% 3	370
	11th to 20th	Day	28% 28% 31% 11% 2 1	388
	21st to end	Day	26% 22% 35% 14% 2	382
March	1st to 10th	Day	30% 25% 30% 13% 2	460
	11th to 20th	Day	28% 20% 33% 14% 3 1	460
	21st to end	Day	34% 19% 29% 13% 4 1	506
April	1st to 10th	Day	39% 20% 25% 11% 3 2	460
	11th to 20th	Day	35% 21% 27% 12% 4	452
	21st to end	Day	35% 18% 32% 11% 3 1	460
May	1st to 10th	Day	33% 18% 29% 16% 3 1	463
	11th to 20th	Day	28% 18% 28% 20% 4 1	487
	21st to end	Day	24% 19% 33% 18% 5% 1	735
June	1st to 10th	Day	31% 13% 30% 18% 7% 1	680
	11th to 20th	Day	25% 14% 28% 21% 10% 2	680
	21st to end	Day	30% 11% 31% 22% 7% 1	680
July	1st to 10th	Day	20% 11% 34% 25% 8% 1	670
	11th to 20th	Day	22% 10% 36% 23% 8% 2	515
	21st to end	Day	17% 8% 38% 30% 6% 2	532
August	1st to 10th	Day	18% 9% 36% 26% 9% 2	486
	11th to 20th	Day	19% 11% 28% 31% 10% 2	479
	21st to end	Day	19% 14% 27% 28% 10% 2	539
September	1st to 10th	Day	15% 13% 36% 24% 9% 3	490
	11th to 20th	Day	23% 11% 30% 19% 14% 4	490
	21st to end	Day	19% 15% 34% 19% 9% 4	490
October	1st to 10th	Day	24% 13% 28% 21% 11% 3	443
	11th to 20th	Day	26% 17% 31% 16% 8% 2	390
	21st to end	Day	30% 19% 30% 16% 4 1	429
November	1st to 10th	Day	30% 17% 31% 15% 6% 2	395
	11th to 20th	Day	31% 20% 29% 14% 6%	373
	21st to end	Day	31% 21% 28% 17% 3	370
December	1st to 10th	Day	31% 18% 35% 13% 4	268
	11th to 20th	Day	37% 23% 31% 8% 1	180
	21st to end	Day	37% 23% 27% 9% 4	198
January	1st to 10th	Night	25% 19% 33% 21% 2	801
	11th to 20th	Night	27% 19% 33% 18% 4	760
	21st to end	Night	19% 18% 39% 19% 3 1	836
February	1st to 10th	Night	24% 20% 35% 18% 3	760
	11th to 20th	Night	24% 24% 36% 14% 2 1	743
	21st to end	Night	25% 20% 32% 20% 3	628
March	1st to 10th	Night	28% 16% 35% 19% 1	760
	11th to 20th	Night	26% 19% 33% 19% 4	760
	21st to end	Night	26% 18% 32% 19% 5%	836
April	1st to 10th	Night	32% 17% 32% 16% 3	741
	11th to 20th	Night	28% 17% 34% 16% 5%	564
	21st to end	Night	34% 14% 31% 17% 5%	570
May	1st to 10th	Night	29% 13% 30% 24% 4	570
	11th to 20th	Night	25% 15% 35% 19% 6%	562
	21st to end	Night	20% 14% 35% 25% 6%	461
June	1st to 10th	Night	29% 8% 33% 24% 6%	380
	11th to 20th	Night	21% 8% 36% 27% 9%	380
	21st to end	Night	30% 7% 29% 30% 5%	380
July	1st to 10th	Night	17% 6% 38% 34% 6%	370
	11th to 20th	Night	19% 5% 30% 37% 8% 1	368
	21st to end	Night	18% 3 33% 37% 9%	449
August	1st to 10th	Night	20% 4 31% 35% 10%	568
	11th to 20th	Night	19% 6% 28% 34% 12% 1	562
	21st to end	Night	15% 8% 29% 33% 14% 1	627
September	1st to 10th	Night	17% 8% 35% 28% 12%	703
	11th to 20th	Night	19% 9% 27% 30% 14% 2	760
	21st to end	Night	21% 11% 31% 25% 11% 1	760
October	1st to 10th	Night	23% 9% 27% 27% 13%	760
	11th to 20th	Night	21% 15% 32% 23% 8% 1	760
	21st to end	Night	30% 16% 32% 19% 3	836
November	1st to 10th	Night	25% 17% 31% 20% 5% 1	780
	11th to 20th	Night	26% 18% 30% 18% 8% 1	828
	21st to end	Night	28% 19% 31% 18% 3 1	850
December	1st to 10th	Night	31% 16% 31% 17% 4	850
	11th to 20th	Night	30% 21% 29% 18% 2	850
	21st to end	Night	31% 20% 31% 14% 4	935

Page generated at 2024-11-08 22:45:41. Version ac07

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