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 2024-03-23.

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% 7% 3 6% 6% 3 5% 5% 6% 7% 37%	78770
	Night	14% 7% 3 6% 6% 3 5% 5% 5% 7% 39%	81112
Transparency	Day	44% 9% 13% 20% 12% 2	78485
	Night	42% 9% 13% 22% 12% 2	80916
Seeing	Day	23% 15% 26% 20% 12% 4	13941
	Night	20% 14% 25% 28% 13% 1	23697

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	16% 12% 5% 8% 6% 3 4 4 4 5% 34%	2713
	11th to 20th	Day	12% 14% 7% 11% 9% 4 5% 4 4 4 26%	2840
	21st to end	Day	17% 14% 5% 8% 7% 3 5% 4 4 6% 27%	3124
February	1st to 10th	Day	14% 12% 4 8% 6% 3 5% 5% 4 7% 33%	1710
	11th to 20th	Day	13% 8% 4 9% 7% 4 6% 5% 5% 6% 33%	1663
	21st to end	Day	17% 8% 4 10% 6% 3 3 4 4 5% 35%	1579
March	1st to 10th	Day	13% 8% 4 6% 5% 3 4 4 5% 5% 42%	2090
	11th to 20th	Day	16% 8% 4 6% 6% 3 4 5% 4 7% 36%	2090
	21st to end	Day	17% 9% 4 7% 6% 3 4 4 4 6% 36%	2200
April	1st to 10th	Day	13% 9% 4 7% 6% 3 5% 5% 5% 7% 36%	2131
	11th to 20th	Day	13% 7% 4 5% 5% 4 5% 4 4 7% 41%	2134
	21st to end	Day	20% 7% 2 5% 4 3 5% 5% 5% 7% 36%	2250
May	1st to 10th	Day	17% 7% 3 6% 6% 4 7% 5% 7% 6% 33%	2340
	11th to 20th	Day	21% 8% 2 5% 5% 3 5% 5% 4 8% 35%	2326
	21st to end	Day	14% 6% 3 6% 5% 3 6% 6% 7% 8% 37%	2725
June	1st to 10th	Day	13% 4 3 5% 5% 3 5% 5% 7% 9% 40%	2520
	11th to 20th	Day	11% 5% 2 6% 6% 4 7% 7% 8% 9% 35%	2520
	21st to end	Day	9% 4 2 5% 5% 3 6% 6% 7% 11% 40%	2520
July	1st to 10th	Day	9% 5% 2 5% 6% 4 6% 7% 6% 8% 41%	2520
	11th to 20th	Day	7% 4 3 5% 6% 4 6% 7% 7% 11% 41%	2352
	21st to end	Day	11% 5% 3 6% 6% 4 7% 6% 6% 9% 37%	2547
August	1st to 10th	Day	10% 5% 3 6% 6% 4 8% 7% 7% 9% 35%	2327
	11th to 20th	Day	13% 4 2 5% 6% 4 5% 5% 7% 9% 40%	2299
	21st to end	Day	12% 5% 2 5% 5% 3 6% 6% 7% 8% 43%	2376
September	1st to 10th	Day	16% 5% 2 4 5% 3 4 4 6% 7% 43%	2160
	11th to 20th	Day	13% 5% 2 6% 4 2 4 5% 5% 7% 49%	2085
	21st to end	Day	17% 7% 2 5% 5% 3 5% 6% 6% 6% 38%	1921
October	1st to 10th	Day	17% 5% 2 5% 4 3 4 5% 6% 6% 44%	1800
	11th to 20th	Day	16% 7% 2 6% 6% 3 4 5% 5% 6% 41%	1800
	21st to end	Day	15% 6% 3 5% 5% 3 4 5% 5% 7% 41%	1980
November	1st to 10th	Day	10% 6% 3 5% 4 3 5% 4 5% 7% 50%	1843
	11th to 20th	Day	15% 8% 3 5% 5% 3 5% 5% 6% 6% 41%	1563
	21st to end	Day	15% 8% 3 5% 6% 3 5% 5% 6% 6% 37%	1520
December	1st to 10th	Day	18% 9% 4 8% 7% 4 5% 6% 5% 7% 28%	1520
	11th to 20th	Day	16% 11% 5% 8% 5% 3 4 4 5% 5% 35%	1910
	21st to end	Day	18% 11% 4 8% 8% 4 6% 5% 5% 6% 25%	2772
January	1st to 10th	Night	12% 11% 4 8% 8% 4 6% 6% 5% 6% 31%	4228
	11th to 20th	Night	14% 12% 5% 9% 7% 3 4 4 4 5% 33%	4120
	21st to end	Night	20% 12% 4 8% 7% 3 5% 4 4 5% 29%	4532
February	1st to 10th	Night	14% 8% 3 5% 6% 4 5% 5% 5% 7% 38%	2470
	11th to 20th	Night	14% 9% 4 7% 6% 3 5% 5% 5% 7% 34%	2403
	21st to end	Night	15% 9% 5% 7% 6% 3 4 5% 6% 7% 32%	1869
March	1st to 10th	Night	14% 7% 2 5% 4 2 4 5% 5% 7% 44%	2090
	11th to 20th	Night	17% 7% 3 5% 6% 3 4 4 5% 7% 40%	2090
	21st to end	Night	16% 8% 3 5% 5% 3 4 4 5% 6% 41%	2201
April	1st to 10th	Night	16% 8% 3 6% 6% 4 4 4 5% 6% 38%	1828
	11th to 20th	Night	14% 6% 2 4 5% 3 5% 5% 6% 8% 42%	1775
	21st to end	Night	18% 4 2 4 5% 3 4 5% 5% 8% 42%	1725
May	1st to 10th	Night	17% 8% 3 6% 4 3 5% 5% 6% 8% 36%	1620
	11th to 20th	Night	19% 6% 4 5% 5% 3 5% 4 5% 6% 39%	1563
	21st to end	Night	13% 5% 2 3 4 4 5% 5% 6% 10% 44%	1550
June	1st to 10th	Night	12% 4 2 3 4 3 5% 6% 5% 9% 47%	1440
	11th to 20th	Night	12% 4 2 5% 6% 3 6% 5% 7% 9% 41%	1440
	21st to end	Night	8% 4 2 4 5% 3 4 5% 9% 10% 44%	1440
July	1st to 10th	Night	9% 4 2 4 6% 3 6% 5% 7% 8% 44%	1440
	11th to 20th	Night	5% 4 2 4 5% 3 5% 5% 6% 10% 49%	1603
	21st to end	Night	9% 3 2 4 6% 3 5% 7% 8% 11% 42%	1771
August	1st to 10th	Night	7% 6% 2 6% 5% 4 6% 6% 7% 8% 42%	1611
	11th to 20th	Night	9% 5% 2 6% 6% 3 5% 5% 5% 7% 46%	1598
	21st to end	Night	11% 5% 2 4 4 4 5% 5% 5% 9% 46%	1964
September	1st to 10th	Night	16% 4 2 5% 5% 2 5% 3 4 6% 47%	1800
	11th to 20th	Night	12% 5% 2 4 4 3 4 4 5% 6% 51%	1872
	21st to end	Night	18% 5% 2 4 4 3 4 5% 5% 6% 43%	2038
October	1st to 10th	Night	17% 5% 3 5% 5% 3 4 4 5% 6% 43%	2160
	11th to 20th	Night	15% 6% 2 4 4 3 4 4 4 8% 47%	2160
	21st to end	Night	17% 5% 2 5% 5% 3 4 4 5% 6% 44%	2376
November	1st to 10th	Night	10% 6% 3 6% 4 3 4 4 4 6% 50%	2234
	11th to 20th	Night	14% 9% 3 5% 5% 3 4 4 5% 7% 40%	2612
	21st to end	Night	14% 7% 3 6% 6% 3 5% 5% 5% 7% 38%	2660
December	1st to 10th	Night	16% 10% 4 7% 6% 4 5% 5% 5% 6% 33%	2660
	11th to 20th	Night	15% 8% 3 6% 6% 4 5% 5% 5% 6% 36%	3285
	21st to end	Night	16% 10% 4 8% 7% 4 6% 5% 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	43% 6% 13% 23% 13% 1	2090
	11th to 20th	Day	46% 7% 12% 20% 12% 3	2090
	21st to end	Day	49% 7% 11% 20% 12% 2	2200
April	1st to 10th	Day	47% 8% 12% 17% 13% 3	2131
	11th to 20th	Day	42% 7% 12% 18% 17% 4	2134
	21st to end	Day	46% 7% 11% 22% 11% 3	2250
May	1st to 10th	Day	48% 10% 12% 17% 12% 1	2340
	11th to 20th	Day	47% 8% 12% 19% 11% 3	2330
	21st to end	Day	42% 10% 14% 22% 10% 1	2725
June	1st to 10th	Day	39% 10% 14% 21% 14% 1	2520
	11th to 20th	Day	40% 13% 14% 19% 12% 1	2520
	21st to end	Day	35% 11% 17% 23% 13% 1	2520
July	1st to 10th	Day	38% 12% 14% 21% 13% 3	2450
	11th to 20th	Day	34% 12% 15% 21% 16% 2	2282
	21st to end	Day	40% 10% 14% 20% 14% 2	2405
August	1st to 10th	Day	40% 13% 17% 20% 10%	2314
	11th to 20th	Day	38% 11% 14% 23% 12% 1	2299
	21st to end	Day	37% 9% 16% 24% 12% 3	2376
September	1st to 10th	Day	40% 9% 13% 18% 17% 4	2160
	11th to 20th	Day	35% 7% 12% 26% 17% 3	2085
	21st to end	Day	43% 9% 12% 18% 17% 1	1921
October	1st to 10th	Day	39% 9% 14% 21% 15% 3	1800
	11th to 20th	Day	42% 8% 10% 25% 14% 1	1800
	21st to end	Day	41% 7% 12% 24% 14% 2	1980
November	1st to 10th	Day	34% 6% 13% 23% 19% 4	1843
	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	39% 7% 13% 27% 13% 1	2090
	11th to 20th	Night	43% 8% 12% 22% 13% 2	2090
	21st to end	Night	43% 8% 13% 20% 13% 4	2201
April	1st to 10th	Night	46% 8% 12% 17% 15% 3	1828
	11th to 20th	Night	39% 8% 13% 20% 15% 4	1775
	21st to end	Night	39% 8% 12% 25% 11% 3	1725
May	1st to 10th	Night	43% 9% 11% 21% 12% 4	1620
	11th to 20th	Night	46% 7% 13% 17% 15% 2	1564
	21st to end	Night	35% 10% 18% 25% 12% 1	1551
June	1st to 10th	Night	33% 10% 12% 27% 16% 2	1440
	11th to 20th	Night	37% 10% 15% 25% 11% 1	1440
	21st to end	Night	31% 9% 19% 24% 15% 2	1440
July	1st to 10th	Night	35% 11% 15% 22% 13% 4	1400
	11th to 20th	Night	29% 10% 16% 25% 16% 2	1550
	21st to end	Night	30% 12% 20% 21% 15% 2	1672
August	1st to 10th	Night	35% 11% 17% 22% 14% 1	1600
	11th to 20th	Night	35% 10% 15% 23% 17% 1	1598
	21st to end	Night	34% 9% 15% 25% 15% 3	1964
September	1st to 10th	Night	37% 7% 14% 21% 17% 4	1800
	11th to 20th	Night	32% 7% 12% 27% 20% 2	1872
	21st to end	Night	40% 8% 12% 22% 17% 1	2038
October	1st to 10th	Night	40% 7% 13% 24% 15% 1	2160
	11th to 20th	Night	35% 7% 14% 26% 16% 1	2160
	21st to end	Night	39% 7% 10% 26% 17% 1	2376
November	1st to 10th	Night	35% 6% 13% 23% 19% 4	2234
	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	30% 22% 29% 14% 5% 1	470
April	1st to 10th	Day	28% 23% 23% 19% 5% 1	420
	11th to 20th	Day	22% 21% 27% 17% 9% 5%	412
	21st to end	Day	34% 17% 27% 13% 7% 2	420
May	1st to 10th	Day	30% 17% 27% 15% 9% 3	423
	11th to 20th	Day	26% 16% 28% 18% 8% 4	447
	21st to end	Day	22% 11% 22% 24% 14% 8%	485
June	1st to 10th	Day	17% 14% 29% 22% 15% 4	450
	11th to 20th	Day	18% 11% 29% 23% 13% 6%	450
	21st to end	Day	13% 13% 28% 25% 17% 4	450
July	1st to 10th	Day	13% 6% 24% 27% 18% 11%	445
	11th to 20th	Day	7% 5% 27% 33% 20% 8%	444
	21st to end	Day	14% 6% 26% 29% 18% 6%	488
August	1st to 10th	Day	13% 9% 21% 28% 21% 10%	446
	11th to 20th	Day	15% 3 23% 28% 21% 10%	439
	21st to end	Day	15% 4 26% 23% 21% 12%	495
September	1st to 10th	Day	20% 8% 20% 21% 22% 10%	450
	11th to 20th	Day	17% 5% 18% 30% 21% 9%	450
	21st to end	Day	25% 11% 24% 22% 15% 4	450
October	1st to 10th	Day	21% 9% 23% 23% 20% 4	450
	11th to 20th	Day	21% 16% 27% 24% 11% 1	450
	21st to end	Day	22% 21% 27% 20% 9% 1	495
November	1st to 10th	Day	16% 16% 29% 26% 12% 2	449
	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% 17% 33% 20% 5% 1	801
April	1st to 10th	Night	24% 21% 28% 22% 5%	720
	11th to 20th	Night	19% 17% 27% 28% 9%	711
	21st to end	Night	22% 14% 26% 29% 9%	645
May	1st to 10th	Night	21% 12% 25% 29% 13% 1	540
	11th to 20th	Night	25% 8% 22% 33% 12%	502
	21st to end	Night	15% 7% 17% 33% 25% 2	389
June	1st to 10th	Night	14% 4 24% 36% 22%	360
	11th to 20th	Night	13% 6% 22% 37% 21% 1	360
	21st to end	Night	10% 3 22% 42% 22% 1	360
July	1st to 10th	Night	11% 4 16% 38% 27% 4	350
	11th to 20th	Night	8% 2 13% 37% 36% 4	506
	21st to end	Night	9% 3 19% 37% 31% 2	591
August	1st to 10th	Night	9% 3 15% 40% 30% 3	537
	11th to 20th	Night	11% 4 13% 39% 29% 5%	534
	21st to end	Night	14% 3 16% 34% 29% 4	776
September	1st to 10th	Night	18% 4 17% 31% 25% 5%	720
	11th to 20th	Night	16% 5% 15% 32% 29% 4	720
	21st to end	Night	23% 8% 18% 29% 20% 3	720
October	1st to 10th	Night	21% 7% 21% 28% 22% 2	720
	11th to 20th	Night	18% 14% 25% 30% 12% 1	720
	21st to end	Night	22% 15% 24% 28% 10% 1	792
November	1st to 10th	Night	14% 12% 26% 35% 12% 1	740
	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 2024-03-19 23:31:08. Version ac07

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