Forks of the Credit
Clear Sky Chart
History

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

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	15% 11% 4 9% 5% 5% 5% 4 5% 7% 31%	101971
	Night	14% 10% 4 9% 5% 4 5% 4 5% 6% 33%	97042
Transparency	Day	50% 4 13% 21% 11% 1	105575
	Night	49% 4 13% 22% 11% 1	101528
Seeing	Day	21% 17% 32% 19% 9% 3	14836
	Night	20% 17% 31% 22% 9% 1	23829

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	15% 17% 8% 13% 5% 4 4 3 4 5% 22%	2517
	11th to 20th	Day	11% 20% 9% 20% 8% 6% 5% 3 4 4 9%	2811
	21st to end	Day	20% 20% 8% 13% 6% 5% 4 2 3 5% 14%	3124
February	1st to 10th	Day	13% 17% 6% 16% 8% 6% 5% 4 5% 5% 17%	1710
	11th to 20th	Day	12% 13% 6% 16% 8% 5% 4 3 5% 7% 21%	1663
	21st to end	Day	16% 17% 6% 11% 6% 4 6% 3 4 5% 23%	1479
March	1st to 10th	Day	18% 14% 5% 10% 6% 4 4 3 4 5% 28%	3424
	11th to 20th	Day	10% 16% 8% 11% 6% 5% 4 4 4 6% 27%	3480
	21st to end	Day	15% 12% 4 7% 5% 4 5% 4 5% 6% 33%	3815
April	1st to 10th	Day	17% 15% 4 9% 5% 3 4 4 5% 7% 28%	2221
	11th to 20th	Day	19% 11% 3 7% 5% 4 3 4 4 6% 35%	2362
	21st to end	Day	21% 10% 4 7% 4 4 4 3 5% 6% 32%	2470
May	1st to 10th	Day	18% 9% 3 7% 4 5% 4 3 5% 7% 34%	4108
	11th to 20th	Day	17% 10% 3 8% 5% 5% 5% 4 5% 7% 32%	4320
	21st to end	Day	12% 5% 2 6% 4 4 4 3 6% 7% 46%	4837
June	1st to 10th	Day	14% 7% 2 6% 6% 5% 5% 5% 6% 9% 36%	2660
	11th to 20th	Day	12% 6% 2 6% 5% 5% 5% 4 7% 10% 39%	2745
	21st to end	Day	14% 6% 2 7% 5% 5% 5% 4 7% 9% 37%	2850
July	1st to 10th	Day	11% 5% 2 6% 5% 5% 5% 5% 8% 10% 38%	4696
	11th to 20th	Day	10% 5% 2 6% 4 5% 5% 5% 7% 8% 43%	4414
	21st to end	Day	10% 5% 2 6% 5% 5% 6% 5% 7% 9% 40%	4466
August	1st to 10th	Day	16% 7% 2 6% 5% 5% 5% 4 6% 8% 35%	4104
	11th to 20th	Day	12% 8% 4 8% 5% 6% 6% 4 7% 9% 32%	4044
	21st to end	Day	10% 6% 2 7% 5% 5% 6% 4 6% 8% 40%	4404
September	1st to 10th	Day	13% 7% 3 8% 5% 5% 5% 4 6% 8% 38%	2280
	11th to 20th	Day	12% 8% 3 6% 4 3 3 5% 6% 8% 43%	2132
	21st to end	Day	16% 8% 3 7% 5% 5% 6% 3 6% 8% 32%	2074
October	1st to 10th	Day	18% 11% 3 8% 5% 4 4 4 5% 6% 32%	1900
	11th to 20th	Day	21% 13% 4 7% 5% 5% 4 3 5% 6% 27%	1900
	21st to end	Day	24% 16% 4 9% 5% 4 4 4 4 6% 20%	2090
November	1st to 10th	Day	13% 17% 4 7% 5% 5% 4 5% 5% 7% 28%	1633
	11th to 20th	Day	13% 15% 6% 10% 4 6% 5% 4 6% 8% 23%	1520
	21st to end	Day	16% 18% 6% 11% 6% 5% 6% 3 5% 6% 19%	1520
December	1st to 10th	Day	14% 22% 7% 13% 7% 5% 4 3 5% 5% 14%	1520
	11th to 20th	Day	17% 19% 6% 12% 6% 4 4 3 5% 5% 18%	1906
	21st to end	Day	25% 22% 8% 17% 4 3 4 3 3 3 9%	2772
January	1st to 10th	Night	16% 15% 8% 14% 6% 4 4 4 4 6% 18%	4429
	11th to 20th	Night	12% 13% 8% 17% 11% 9% 7% 4 4 5% 9%	4148
	21st to end	Night	19% 14% 7% 13% 6% 5% 5% 3 5% 6% 16%	4532
February	1st to 10th	Night	12% 16% 5% 12% 7% 5% 5% 4 6% 6% 22%	2470
	11th to 20th	Night	11% 12% 6% 14% 8% 6% 4 4 5% 7% 23%	2403
	21st to end	Night	12% 14% 5% 11% 5% 5% 5% 4 6% 7% 26%	1970
March	1st to 10th	Night	16% 10% 5% 10% 5% 5% 5% 4 6% 6% 29%	3415
	11th to 20th	Night	11% 10% 5% 9% 5% 4 5% 3 6% 6% 37%	3479
	21st to end	Night	15% 8% 3 7% 4 4 4 3 5% 5% 41%	3817
April	1st to 10th	Night	18% 13% 3 7% 6% 5% 4 4 4 6% 32%	1958
	11th to 20th	Night	15% 9% 4 7% 5% 5% 4 3 4 6% 38%	1782
	21st to end	Night	15% 10% 3 9% 5% 5% 4 3 5% 7% 34%	1710
May	1st to 10th	Night	17% 8% 2 6% 4 4 4 3 5% 6% 41%	2833
	11th to 20th	Night	16% 9% 3 6% 5% 4 4 3 5% 7% 38%	2571
	21st to end	Night	10% 5% 2 5% 3 3 4 4 5% 7% 52%	2738
June	1st to 10th	Night	11% 6% 2 7% 5% 5% 5% 4 5% 8% 42%	1520
	11th to 20th	Night	8% 5% 2 7% 5% 5% 5% 5% 7% 9% 42%	1427
	21st to end	Night	11% 6% 2 6% 5% 2 4 4 6% 6% 48%	1330
July	1st to 10th	Night	7% 5% 2 5% 4 4 4 4 6% 8% 51%	2267
	11th to 20th	Night	11% 3 2 5% 4 4 4 2 5% 8% 52%	2542
	21st to end	Night	7% 4 1 5% 4 5% 5% 4 7% 8% 51%	3087
August	1st to 10th	Night	12% 5% 2 6% 4 4 5% 4 6% 6% 48%	2825
	11th to 20th	Night	12% 5% 2 5% 3 4 4 4 5% 8% 47%	2785
	21st to end	Night	11% 5% 2 5% 4 5% 5% 3 5% 7% 48%	3220
September	1st to 10th	Night	9% 5% 2 6% 5% 4 4 4 6% 7% 49%	1900
	11th to 20th	Night	11% 4 2 5% 3 3 3 3 6% 8% 53%	2045
	21st to end	Night	15% 9% 2 7% 4 4 4 3 5% 6% 41%	2105
October	1st to 10th	Night	16% 7% 3 7% 5% 5% 4 3 5% 7% 38%	2280
	11th to 20th	Night	18% 11% 3 8% 4 5% 5% 4 4 5% 34%	2280
	21st to end	Night	20% 11% 4 8% 5% 5% 5% 4 5% 6% 27%	2508
November	1st to 10th	Night	15% 10% 4 6% 6% 4 4 5% 6% 6% 35%	2514
	11th to 20th	Night	15% 13% 5% 9% 5% 6% 5% 4 6% 7% 26%	2660
	21st to end	Night	17% 13% 5% 10% 6% 4 4 4 5% 7% 25%	2660
December	1st to 10th	Night	17% 17% 7% 10% 6% 4 5% 4 5% 6% 18%	2660
	11th to 20th	Night	14% 19% 6% 12% 7% 4 5% 5% 4 6% 18%	3288
	21st to end	Night	25% 21% 7% 15% 5% 3 4 3 4 4 9%	4884

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	63% 2 13% 14% 7%	2518
	11th to 20th	Day	75% 3 9% 9% 3	2811
	21st to end	Day	74% 2 9% 10% 4 1	3124
February	1st to 10th	Day	67% 2 10% 15% 4 1	1710
	11th to 20th	Day	61% 2 12% 16% 7% 1	1672
	21st to end	Day	62% 2 12% 15% 8% 1	1479
March	1st to 10th	Day	59% 3 11% 18% 8% 1	3427
	11th to 20th	Day	56% 3 10% 21% 8% 2	3480
	21st to end	Day	51% 3 10% 22% 12% 2	3815
April	1st to 10th	Day	56% 3 11% 19% 11% 1	2221
	11th to 20th	Day	50% 3 10% 21% 15% 1	2362
	21st to end	Day	53% 3 11% 19% 12% 2	2470
May	1st to 10th	Day	49% 3 12% 22% 12% 2	4120
	11th to 20th	Day	53% 3 14% 22% 8% 1	4324
	21st to end	Day	37% 4 14% 23% 18% 4	4837
June	1st to 10th	Day	44% 5% 12% 24% 14% 1	2660
	11th to 20th	Day	38% 5% 14% 25% 16% 1	2745
	21st to end	Day	42% 5% 13% 26% 14% 1	2850
July	1st to 10th	Day	39% 5% 16% 24% 15% 2	4624
	11th to 20th	Day	34% 5% 13% 35% 11% 1	4339
	21st to end	Day	38% 7% 13% 24% 17% 1	4324
August	1st to 10th	Day	45% 5% 14% 23% 12% 1	4091
	11th to 20th	Day	45% 5% 16% 25% 9%	4083
	21st to end	Day	39% 5% 14% 32% 10% 1	4404
September	1st to 10th	Day	42% 5% 13% 28% 11% 2	2280
	11th to 20th	Day	38% 4 13% 30% 14% 1	2132
	21st to end	Day	49% 5% 13% 24% 9%	2074
October	1st to 10th	Day	43% 5% 13% 25% 13% 1	3160
	11th to 20th	Day	44% 4 14% 23% 15%	3140
	21st to end	Day	57% 5% 12% 19% 7%	3428
November	1st to 10th	Day	51% 4 15% 21% 8% 1	1633
	11th to 20th	Day	56% 6% 14% 15% 8%	1520
	21st to end	Day	64% 4 13% 16% 3	1520
December	1st to 10th	Day	69% 4 12% 12% 4	1520
	11th to 20th	Day	67% 4 12% 12% 5%	1906
	21st to end	Day	81% 3 7% 8% 1	2772
January	1st to 10th	Night	65% 2 13% 16% 3	4429
	11th to 20th	Night	74% 3 10% 10% 3 1	4148
	21st to end	Night	68% 2 12% 13% 4 1	4532
February	1st to 10th	Night	59% 4 11% 20% 5% 1	2470
	11th to 20th	Night	58% 4 11% 18% 8%	2405
	21st to end	Night	55% 4 13% 19% 9% 1	1970
March	1st to 10th	Night	53% 4 12% 23% 7% 1	3425
	11th to 20th	Night	45% 3 14% 25% 11% 2	3480
	21st to end	Night	45% 2 9% 26% 17% 2	3817
April	1st to 10th	Night	53% 4 9% 20% 14% 1	1958
	11th to 20th	Night	46% 5% 9% 22% 16% 2	1782
	21st to end	Night	48% 3 11% 20% 16% 2	1710
May	1st to 10th	Night	45% 4 11% 20% 16% 4	2840
	11th to 20th	Night	46% 5% 14% 24% 10% 2	2572
	21st to end	Night	31% 3 16% 25% 23% 3	2739
June	1st to 10th	Night	38% 5% 12% 26% 18% 1	1520
	11th to 20th	Night	35% 5% 13% 26% 20% 1	1427
	21st to end	Night	36% 4 14% 28% 17% 1	1330
July	1st to 10th	Night	29% 4 16% 25% 21% 4	2231
	11th to 20th	Night	29% 5% 12% 36% 17% 1	2494
	21st to end	Night	29% 8% 15% 31% 16% 2	2988
August	1st to 10th	Night	35% 4 13% 30% 15% 2	2814
	11th to 20th	Night	34% 5% 15% 31% 14% 1	2812
	21st to end	Night	34% 5% 12% 32% 15% 1	3220
September	1st to 10th	Night	33% 6% 15% 30% 15% 1	1900
	11th to 20th	Night	30% 4 12% 34% 19% 1	2045
	21st to end	Night	44% 4 14% 28% 11% 1	2105
October	1st to 10th	Night	34% 3 10% 28% 24% 1	3800
	11th to 20th	Night	45% 3 12% 25% 15% 1	3779
	21st to end	Night	43% 5% 17% 25% 10%	4120
November	1st to 10th	Night	46% 5% 14% 23% 11% 1	2514
	11th to 20th	Night	54% 4 14% 18% 9% 1	2660
	21st to end	Night	56% 5% 18% 18% 3 1	2660
December	1st to 10th	Night	63% 4 13% 16% 4	2660
	11th to 20th	Night	64% 4 14% 14% 4	3288
	21st to end	Night	76% 3 10% 8% 2	4884

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	24% 27% 31% 15% 3 1	180
	11th to 20th	Day	26% 30% 29% 12% 3 1	263
	21st to end	Day	27% 28% 32% 10% 2	297
February	1st to 10th	Day	27% 33% 29% 10% 1	270
	11th to 20th	Day	26% 34% 33% 7%	270
	21st to end	Day	41% 25% 30% 3	225
March	1st to 10th	Day	24% 24% 31% 17% 4	452
	11th to 20th	Day	23% 24% 37% 12% 4	460
	21st to end	Day	30% 19% 33% 12% 4 1	506
April	1st to 10th	Day	26% 25% 32% 12% 5%	460
	11th to 20th	Day	31% 21% 27% 13% 6% 2	452
	21st to end	Day	25% 18% 36% 14% 5% 2	460
May	1st to 10th	Day	24% 17% 32% 17% 8% 3	463
	11th to 20th	Day	18% 15% 33% 21% 10% 3	487
	21st to end	Day	14% 14% 33% 25% 11% 4	529
June	1st to 10th	Day	16% 16% 35% 24% 8% 1	490
	11th to 20th	Day	16% 13% 33% 24% 12% 2	575
	21st to end	Day	18% 13% 36% 24% 8% 3	680
July	1st to 10th	Day	10% 8% 35% 28% 15% 4	635
	11th to 20th	Day	13% 10% 30% 25% 15% 6%	484
	21st to end	Day	10% 8% 36% 27% 13% 5%	532
August	1st to 10th	Day	12% 9% 31% 27% 16% 6%	486
	11th to 20th	Day	11% 7% 29% 26% 19% 7%	479
	21st to end	Day	14% 9% 31% 26% 16% 5%	539
September	1st to 10th	Day	14% 11% 30% 23% 13% 8%	490
	11th to 20th	Day	11% 7% 27% 24% 20% 11%	490
	21st to end	Day	19% 15% 27% 20% 14% 5%	490
October	1st to 10th	Day	24% 18% 26% 18% 10% 3	490
	11th to 20th	Day	26% 21% 32% 13% 7% 1	490
	21st to end	Day	32% 21% 27% 16% 4	539
November	1st to 10th	Day	29% 19% 32% 16% 4 1	255
	11th to 20th	Day	29% 24% 31% 10% 5% 1	180
	21st to end	Day	26% 25% 39% 9% 1	180
December	1st to 10th	Day	33% 32% 28% 8%	180
	11th to 20th	Day	33% 31% 27% 8% 1	180
	21st to end	Day	31% 30% 30% 8% 2	198
January	1st to 10th	Night	23% 27% 34% 13% 4	760
	11th to 20th	Night	26% 24% 30% 16% 3	760
	21st to end	Night	17% 20% 38% 20% 6%	836
February	1st to 10th	Night	22% 29% 32% 16% 1	760
	11th to 20th	Night	22% 24% 36% 14% 3	743
	21st to end	Night	21% 27% 35% 14% 2	628
March	1st to 10th	Night	22% 20% 35% 20% 4	760
	11th to 20th	Night	22% 22% 35% 15% 5%	760
	21st to end	Night	21% 17% 36% 20% 6%	836
April	1st to 10th	Night	26% 17% 35% 21% 2	760
	11th to 20th	Night	21% 17% 34% 19% 7% 1	658
	21st to end	Night	20% 14% 34% 25% 7%	570
May	1st to 10th	Night	17% 12% 31% 28% 10% 2	570
	11th to 20th	Night	16% 10% 33% 29% 11% 1	424
	21st to end	Night	12% 11% 30% 32% 15%	411
June	1st to 10th	Night	13% 8% 36% 31% 12% 1	380
	11th to 20th	Night	11% 9% 30% 36% 14%	380
	21st to end	Night	13% 7% 34% 33% 12% 1	380
July	1st to 10th	Night	6% 7% 29% 38% 19% 1	370
	11th to 20th	Night	9% 6% 32% 34% 18% 1	377
	21st to end	Night	9% 3 31% 38% 18% 2	624
August	1st to 10th	Night	10% 4 26% 35% 24% 1	567
	11th to 20th	Night	7% 5% 23% 39% 23% 2	564
	21st to end	Night	14% 5% 30% 26% 23% 2	684
September	1st to 10th	Night	11% 9% 28% 29% 18% 4	760
	11th to 20th	Night	13% 6% 25% 27% 22% 6%	760
	21st to end	Night	21% 11% 21% 28% 16% 4	760
October	1st to 10th	Night	20% 11% 32% 21% 14% 3	760
	11th to 20th	Night	24% 17% 30% 21% 7% 1	760
	21st to end	Night	25% 21% 29% 20% 4	836
November	1st to 10th	Night	23% 16% 31% 21% 8% 1	755
	11th to 20th	Night	22% 24% 29% 18% 7% 1	760
	21st to end	Night	25% 22% 31% 18% 4	760
December	1st to 10th	Night	28% 24% 32% 13% 3	760
	11th to 20th	Night	24% 26% 35% 13% 3	760
	21st to end	Night	32% 24% 27% 16% 2	836

Page generated at 2024-11-01 22:47:35. Version ac07

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