Rocky Gap State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rocky Gap State Park clear sky chart from 2005-11-06 to 2024-11-03.

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	14% 8% 3 7% 5% 5% 5% 4 6% 7% 37%	101150
	Night	14% 8% 3 7% 5% 4 4 4 5% 7% 39%	97777
Transparency	Day	43% 9% 13% 22% 12% 2	100956
	Night	42% 9% 13% 22% 12% 2	97641
Seeing	Day	22% 15% 26% 21% 12% 4	14841
	Night	20% 14% 24% 28% 13% 1	24427

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	15% 13% 4 9% 5% 4 3 3 4 5% 34%	2713
	11th to 20th	Day	12% 15% 6% 13% 7% 6% 4 3 4 4 26%	2840
	21st to end	Day	17% 14% 4 10% 6% 5% 4 3 4 6% 27%	3124
February	1st to 10th	Day	14% 13% 3 9% 5% 4 5% 4 4 6% 32%	1710
	11th to 20th	Day	13% 9% 4 10% 6% 6% 5% 4 5% 6% 32%	1663
	21st to end	Day	17% 8% 4 11% 5% 4 3 3 4 5% 35%	1579
March	1st to 10th	Day	19% 12% 3 8% 5% 4 4 3 5% 5% 32%	3435
	11th to 20th	Day	12% 7% 3 6% 4 4 4 4 5% 8% 43%	3480
	21st to end	Day	15% 10% 3 7% 5% 4 3 3 4 6% 39%	3815
April	1st to 10th	Day	13% 10% 3 8% 6% 4 5% 4 5% 7% 35%	2250
	11th to 20th	Day	13% 8% 3 6% 6% 5% 4 3 5% 7% 41%	2254
	21st to end	Day	20% 7% 2 6% 4 4 5% 4 6% 6% 36%	2375
May	1st to 10th	Day	24% 7% 3 7% 5% 5% 5% 4 6% 6% 29%	4082
	11th to 20th	Day	23% 8% 2 6% 4 4 5% 4 6% 7% 31%	4134
	21st to end	Day	11% 5% 2 6% 4 4 6% 5% 7% 10% 39%	4823
June	1st to 10th	Day	12% 5% 2 5% 5% 4 5% 5% 7% 9% 40%	2660
	11th to 20th	Day	10% 5% 2 7% 5% 5% 7% 6% 7% 9% 37%	2660
	21st to end	Day	9% 5% 2 6% 5% 5% 5% 5% 8% 11% 40%	2660
July	1st to 10th	Day	6% 4 2 6% 5% 5% 6% 5% 7% 9% 44%	4440
	11th to 20th	Day	7% 5% 2 6% 5% 5% 6% 5% 7% 11% 41%	4132
	21st to end	Day	12% 8% 3 7% 6% 5% 5% 4 6% 8% 37%	4466
August	1st to 10th	Day	16% 6% 3 7% 5% 5% 6% 4 7% 9% 33%	4104
	11th to 20th	Day	10% 5% 2 6% 5% 5% 6% 4 7% 9% 41%	4026
	21st to end	Day	11% 4 1 5% 4 5% 5% 4 7% 8% 46%	4180
September	1st to 10th	Day	15% 5% 2 5% 4 4 4 3 6% 7% 45%	2280
	11th to 20th	Day	13% 5% 2 6% 3 4 4 4 5% 6% 49%	2200
	21st to end	Day	20% 7% 2 6% 4 4 5% 4 6% 6% 36%	2027
October	1st to 10th	Day	17% 6% 2 5% 3 4 4 3 6% 6% 45%	1900
	11th to 20th	Day	16% 7% 2 7% 5% 4 4 3 5% 6% 42%	1900
	21st to end	Day	14% 6% 3 6% 4 5% 4 4 5% 7% 43%	2090
November	1st to 10th	Day	10% 6% 2 5% 3 4 4 3 5% 7% 50%	1863
	11th to 20th	Day	14% 10% 2 6% 4 4 4 4 6% 6% 41%	1563
	21st to end	Day	15% 9% 2 7% 5% 5% 4 3 6% 6% 37%	1520
December	1st to 10th	Day	18% 10% 3 8% 6% 5% 6% 5% 5% 7% 28%	1520
	11th to 20th	Day	16% 12% 5% 8% 5% 4 4 3 5% 5% 34%	1910
	21st to end	Day	18% 11% 3 10% 6% 6% 6% 4 5% 6% 25%	2772
January	1st to 10th	Night	12% 11% 4 9% 6% 6% 5% 4 5% 6% 31%	4228
	11th to 20th	Night	14% 12% 4 10% 5% 5% 4 3 4 5% 33%	4120
	21st to end	Night	20% 12% 4 10% 5% 4 4 3 4 5% 28%	4532
February	1st to 10th	Night	14% 9% 3 7% 5% 6% 4 4 6% 6% 38%	2470
	11th to 20th	Night	14% 10% 4 8% 5% 5% 5% 4 6% 6% 34%	2403
	21st to end	Night	15% 9% 4 8% 6% 5% 4 4 6% 7% 32%	1869
March	1st to 10th	Night	21% 9% 2 6% 4 4 4 4 5% 6% 36%	3418
	11th to 20th	Night	11% 10% 3 7% 4 4 3 3 4 6% 44%	3480
	21st to end	Night	14% 7% 2 6% 4 4 3 3 4 5% 47%	3817
April	1st to 10th	Night	16% 9% 3 7% 5% 4 4 4 6% 5% 37%	1929
	11th to 20th	Night	14% 6% 2 5% 5% 4 5% 4 6% 8% 41%	1875
	21st to end	Night	17% 5% 2 5% 4 4 4 4 5% 8% 42%	1820
May	1st to 10th	Night	24% 9% 3 7% 4 4 5% 3 5% 7% 29%	2813
	11th to 20th	Night	24% 9% 3 7% 5% 4 4 3 5% 5% 32%	2755
	21st to end	Night	11% 5% 2 5% 4 4 6% 4 7% 9% 43%	2732
June	1st to 10th	Night	11% 5% 1 4 4 3 6% 5% 5% 8% 47%	1520
	11th to 20th	Night	11% 4 2 6% 5% 5% 5% 4 7% 9% 42%	1520
	21st to end	Night	8% 5% 2 5% 5% 4 4 4 9% 10% 44%	1520
July	1st to 10th	Night	7% 4 2 5% 5% 5% 6% 5% 8% 9% 44%	2520
	11th to 20th	Night	6% 5% 3 6% 5% 5% 6% 4 7% 10% 43%	2823
	21st to end	Night	10% 6% 2 6% 6% 5% 5% 5% 7% 9% 39%	3087
August	1st to 10th	Night	15% 5% 2 7% 5% 5% 5% 4 7% 9% 35%	2825
	11th to 20th	Night	10% 5% 2 6% 5% 5% 5% 5% 6% 8% 44%	2785
	21st to end	Night	14% 5% 2 5% 3 4 5% 3 5% 8% 47%	3460
September	1st to 10th	Night	15% 5% 2 5% 4 4 3 3 4 7% 48%	1900
	11th to 20th	Night	11% 6% 2 5% 3 4 3 4 5% 6% 51%	1976
	21st to end	Night	21% 6% 2 5% 3 4 4 3 5% 6% 41%	2152
October	1st to 10th	Night	18% 5% 2 5% 4 4 3 3 5% 6% 44%	2280
	11th to 20th	Night	14% 6% 1 5% 3 4 4 3 4 8% 48%	2280
	21st to end	Night	16% 5% 1 6% 4 4 4 4 5% 6% 45%	2508
November	1st to 10th	Night	9% 7% 3 6% 4 4 4 3 4 6% 50%	2259
	11th to 20th	Night	13% 10% 2 6% 5% 4 4 4 6% 6% 40%	2612
	21st to end	Night	14% 8% 3 7% 5% 5% 5% 4 5% 7% 38%	2660
December	1st to 10th	Night	16% 10% 4 8% 5% 5% 5% 4 5% 6% 33%	2660
	11th to 20th	Night	15% 9% 3 8% 5% 6% 5% 4 5% 5% 36%	3285
	21st to end	Night	16% 10% 3 9% 6% 6% 6% 4 6% 8% 26%	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	48% 9% 12% 23% 6% 1	2714
	11th to 20th	Day	58% 8% 11% 13% 9% 1	2840
	21st to end	Day	56% 10% 9% 19% 5% 1	3124
February	1st to 10th	Day	51% 7% 14% 19% 9% 1	1710
	11th to 20th	Day	50% 6% 14% 19% 10% 1	1672
	21st to end	Day	50% 5% 14% 17% 12% 2	1579
March	1st to 10th	Day	50% 9% 11% 20% 9% 1	3435
	11th to 20th	Day	35% 8% 13% 28% 14% 2	3480
	21st to end	Day	44% 9% 12% 21% 12% 2	3815
April	1st to 10th	Day	47% 8% 12% 17% 13% 3	2250
	11th to 20th	Day	42% 7% 11% 19% 17% 4	2254
	21st to end	Day	45% 7% 11% 22% 11% 2	2375
May	1st to 10th	Day	52% 10% 9% 19% 9% 1	4120
	11th to 20th	Day	49% 10% 12% 21% 7% 2	4138
	21st to end	Day	34% 12% 16% 23% 13% 2	4837
June	1st to 10th	Day	38% 10% 14% 22% 14% 1	2660
	11th to 20th	Day	38% 13% 15% 20% 13% 1	2660
	21st to end	Day	35% 11% 17% 23% 13% 1	2660
July	1st to 10th	Day	35% 9% 16% 26% 10% 4	4370
	11th to 20th	Day	34% 9% 18% 25% 13% 1	4062
	21st to end	Day	44% 7% 10% 22% 16% 1	4324
August	1st to 10th	Day	45% 9% 17% 21% 8%	4091
	11th to 20th	Day	38% 8% 12% 27% 15%	4065
	21st to end	Day	34% 8% 15% 27% 14% 2	4180
September	1st to 10th	Day	38% 8% 12% 18% 19% 4	2280
	11th to 20th	Day	35% 7% 11% 27% 18% 2	2200
	21st to end	Day	46% 9% 12% 17% 16% 1	2027
October	1st to 10th	Day	38% 8% 13% 22% 16% 3	1900
	11th to 20th	Day	42% 7% 11% 25% 14% 1	1900
	21st to end	Day	39% 7% 12% 24% 16% 2	2090
November	1st to 10th	Day	34% 6% 13% 23% 19% 4	1863
	11th to 20th	Day	41% 7% 13% 19% 17% 3	1563
	21st to end	Day	44% 8% 14% 23% 10% 1	1520
December	1st to 10th	Day	54% 9% 14% 17% 7%	1520
	11th to 20th	Day	49% 8% 11% 24% 6% 1	1906
	21st to end	Day	54% 11% 14% 12% 8%	2772
January	1st to 10th	Night	47% 12% 11% 19% 10% 1	4228
	11th to 20th	Night	49% 8% 14% 20% 7% 2	4120
	21st to end	Night	53% 9% 10% 21% 5% 1	4532
February	1st to 10th	Night	44% 9% 14% 22% 10% 1	2470
	11th to 20th	Night	49% 8% 11% 19% 13% 1	2405
	21st to end	Night	49% 8% 12% 18% 10% 3	1869
March	1st to 10th	Night	46% 9% 12% 24% 8% 1	3418
	11th to 20th	Night	37% 10% 11% 31% 10% 1	3480
	21st to end	Night	37% 8% 11% 25% 16% 3	3817
April	1st to 10th	Night	45% 9% 12% 16% 15% 3	1929
	11th to 20th	Night	39% 8% 13% 20% 15% 4	1875
	21st to end	Night	38% 9% 13% 26% 11% 3	1820
May	1st to 10th	Night	53% 9% 9% 17% 11% 2	2840
	11th to 20th	Night	48% 10% 13% 19% 9% 1	2756
	21st to end	Night	32% 13% 17% 25% 10% 3	2739
June	1st to 10th	Night	33% 10% 12% 27% 16% 2	1520
	11th to 20th	Night	36% 10% 15% 26% 12% 1	1520
	21st to end	Night	32% 8% 18% 24% 16% 2	1520
July	1st to 10th	Night	34% 9% 18% 21% 12% 6%	2480
	11th to 20th	Night	34% 9% 17% 24% 14% 1	2770
	21st to end	Night	39% 9% 14% 20% 16% 1	2988
August	1st to 10th	Night	43% 9% 18% 22% 9%	2814
	11th to 20th	Night	36% 8% 12% 25% 18% 1	2812
	21st to end	Night	35% 7% 14% 30% 13% 2	3460
September	1st to 10th	Night	36% 7% 13% 21% 19% 4	1900
	11th to 20th	Night	32% 6% 12% 27% 21% 2	1976
	21st to end	Night	42% 8% 12% 21% 16% 1	2152
October	1st to 10th	Night	40% 7% 12% 24% 16% 1	2280
	11th to 20th	Night	34% 7% 13% 26% 17% 2	2280
	21st to end	Night	37% 7% 10% 27% 18% 1	2508
November	1st to 10th	Night	35% 6% 12% 23% 19% 4	2259
	11th to 20th	Night	41% 7% 10% 23% 15% 3	2612
	21st to end	Night	44% 7% 13% 21% 12% 2	2660
December	1st to 10th	Night	50% 7% 13% 21% 8% 1	2660
	11th to 20th	Night	46% 8% 13% 21% 11% 1	3288
	21st to end	Night	50% 13% 17% 14% 6%	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	33% 25% 27% 11% 4	236
	11th to 20th	Day	37% 26% 27% 9% 2	270
	21st to end	Day	32% 26% 27% 12% 3	297
February	1st to 10th	Day	29% 26% 33% 10% 2	270
	11th to 20th	Day	37% 29% 28% 5% 1	270
	21st to end	Day	33% 25% 27% 12% 2	339
March	1st to 10th	Day	30% 22% 27% 17% 3	460
	11th to 20th	Day	30% 27% 26% 12% 4 1	460
	21st to end	Day	29% 22% 29% 14% 5% 1	506
April	1st to 10th	Day	29% 23% 23% 18% 5% 1	460
	11th to 20th	Day	21% 22% 27% 17% 8% 4	452
	21st to end	Day	32% 17% 27% 15% 7% 2	460
May	1st to 10th	Day	30% 16% 26% 15% 9% 3	463
	11th to 20th	Day	26% 16% 27% 18% 9% 4	487
	21st to end	Day	21% 11% 22% 24% 14% 8%	529
June	1st to 10th	Day	18% 14% 29% 20% 16% 4	490
	11th to 20th	Day	17% 10% 29% 25% 13% 6%	490
	21st to end	Day	13% 12% 30% 24% 17% 4	490
July	1st to 10th	Day	12% 6% 25% 27% 18% 10%	485
	11th to 20th	Day	7% 6% 28% 32% 19% 8%	484
	21st to end	Day	15% 6% 27% 29% 18% 5%	532
August	1st to 10th	Day	14% 8% 22% 27% 20% 9%	486
	11th to 20th	Day	15% 4 25% 27% 20% 9%	479
	21st to end	Day	14% 4 25% 23% 22% 11%	539
September	1st to 10th	Day	19% 8% 20% 22% 21% 9%	490
	11th to 20th	Day	17% 5% 18% 31% 22% 9%	490
	21st to end	Day	29% 10% 23% 20% 14% 4	490
October	1st to 10th	Day	21% 9% 24% 23% 18% 4	490
	11th to 20th	Day	20% 16% 27% 24% 11% 2	490
	21st to end	Day	20% 19% 28% 22% 10% 2	539
November	1st to 10th	Day	15% 16% 29% 26% 12% 2	457
	11th to 20th	Day	26% 21% 26% 22% 5%	223
	21st to end	Day	25% 23% 29% 18% 4 1	180
December	1st to 10th	Day	29% 27% 25% 13% 6% 1	180
	11th to 20th	Day	28% 26% 23% 19% 4	180
	21st to end	Day	29% 18% 26% 22% 5%	198
January	1st to 10th	Night	22% 24% 31% 19% 4	760
	11th to 20th	Night	24% 21% 31% 22% 2	760
	21st to end	Night	23% 24% 31% 21% 2	836
February	1st to 10th	Night	22% 20% 30% 25% 3	760
	11th to 20th	Night	25% 27% 31% 16% 1	743
	21st to end	Night	26% 21% 30% 21% 2	628
March	1st to 10th	Night	24% 19% 32% 22% 4	760
	11th to 20th	Night	26% 22% 26% 20% 5% 1	760
	21st to end	Night	23% 18% 33% 20% 5% 1	836
April	1st to 10th	Night	24% 20% 29% 22% 5%	760
	11th to 20th	Night	19% 17% 27% 28% 8%	751
	21st to end	Night	21% 14% 26% 30% 9%	680
May	1st to 10th	Night	22% 12% 24% 29% 13% 1	570
	11th to 20th	Night	24% 9% 22% 32% 12%	530
	21st to end	Night	14% 8% 18% 33% 25% 2	411
June	1st to 10th	Night	13% 5% 24% 36% 22%	380
	11th to 20th	Night	13% 6% 22% 38% 21% 1	380
	21st to end	Night	10% 3 22% 42% 22% 1	380
July	1st to 10th	Night	11% 4 16% 39% 26% 4	370
	11th to 20th	Night	7% 3 13% 38% 35% 4	536
	21st to end	Night	9% 3 18% 37% 30% 2	624
August	1st to 10th	Night	10% 2 15% 40% 29% 3	567
	11th to 20th	Night	10% 4 13% 40% 28% 5%	564
	21st to end	Night	14% 3 16% 34% 29% 4	820
September	1st to 10th	Night	18% 4 17% 32% 25% 4	760
	11th to 20th	Night	15% 5% 14% 32% 30% 4	760
	21st to end	Night	26% 7% 17% 28% 19% 3	760
October	1st to 10th	Night	21% 7% 21% 28% 22% 2	760
	11th to 20th	Night	18% 14% 25% 30% 12% 1	760
	21st to end	Night	21% 14% 24% 29% 11% 1	836
November	1st to 10th	Night	14% 12% 26% 35% 12% 1	749
	11th to 20th	Night	21% 19% 23% 28% 8% 1	760
	21st to end	Night	21% 17% 27% 28% 7%	760
December	1st to 10th	Night	25% 19% 28% 22% 5%	760
	11th to 20th	Night	22% 18% 30% 26% 3	760
	21st to end	Night	22% 19% 27% 30% 3	836

Page generated at 2024-10-31 03:39:23. Version ac07

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