Deep Creek Lake State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Deep Creek Lake State Park clear sky chart from 2005-11-06 to 2024-04-10.

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% 9% 5% 9% 7% 4 5% 5% 6% 7% 30%	83250
	Night	12% 9% 5% 9% 7% 4 5% 5% 5% 7% 32%	85528
Transparency	Day	50% 10% 11% 18% 10% 1	82970
	Night	48% 10% 11% 19% 10% 2	85327
Seeing	Day	26% 19% 26% 17% 9% 3	14009
	Night	23% 19% 25% 22% 10% 1	23860

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% 9% 11% 14% 6% 4 5% 4 5% 6% 22%	2836
	11th to 20th	Day	10% 14% 8% 20% 9% 7% 4 3 4 5% 18%	2840
	21st to end	Day	14% 14% 7% 15% 9% 4 5% 4 4 6% 17%	3124
February	1st to 10th	Day	12% 12% 6% 9% 10% 4 4 6% 6% 6% 25%	1710
	11th to 20th	Day	14% 9% 4 12% 9% 4 7% 5% 6% 7% 23%	1663
	21st to end	Day	13% 12% 6% 12% 7% 5% 5% 4 4 4 26%	1595
March	1st to 10th	Day	16% 9% 6% 8% 6% 4 5% 5% 5% 7% 27%	3435
	11th to 20th	Day	10% 9% 4 9% 6% 3 5% 5% 5% 8% 35%	3480
	21st to end	Day	15% 12% 4 8% 6% 3 5% 4 5% 6% 33%	3815
April	1st to 10th	Day	12% 11% 6% 8% 5% 4 5% 6% 6% 8% 30%	2207
	11th to 20th	Day	15% 9% 5% 7% 5% 3 4 5% 5% 6% 36%	2134
	21st to end	Day	18% 9% 4 7% 6% 4 4 4 5% 7% 31%	2290
May	1st to 10th	Day	18% 10% 3 8% 6% 4 6% 6% 6% 7% 27%	2340
	11th to 20th	Day	22% 7% 3 7% 6% 4 5% 5% 5% 7% 29%	2301
	21st to end	Day	13% 7% 3 6% 6% 4 6% 6% 6% 8% 33%	2677
June	1st to 10th	Day	12% 7% 4 6% 6% 4 6% 6% 8% 8% 34%	2520
	11th to 20th	Day	14% 6% 3 7% 7% 4 6% 7% 6% 9% 30%	2520
	21st to end	Day	11% 6% 3 6% 6% 5% 6% 7% 6% 10% 34%	2520
July	1st to 10th	Day	11% 7% 3 7% 6% 4 6% 6% 6% 8% 35%	2443
	11th to 20th	Day	9% 6% 3 7% 7% 4 7% 6% 7% 9% 35%	2340
	21st to end	Day	12% 6% 5% 7% 7% 3 7% 7% 7% 8% 31%	2547
August	1st to 10th	Day	11% 6% 4 7% 7% 5% 7% 8% 8% 9% 28%	2327
	11th to 20th	Day	13% 7% 3 6% 7% 5% 6% 6% 6% 10% 31%	2303
	21st to end	Day	12% 6% 3 6% 6% 4 6% 7% 6% 8% 35%	2403
September	1st to 10th	Day	15% 5% 3 6% 7% 4 5% 5% 6% 6% 40%	2160
	11th to 20th	Day	11% 7% 3 6% 6% 3 4 6% 6% 8% 40%	2034
	21st to end	Day	17% 9% 3 7% 6% 3 5% 5% 5% 7% 34%	1949
October	1st to 10th	Day	14% 9% 3 5% 6% 4 5% 4 5% 7% 39%	1800
	11th to 20th	Day	16% 13% 3 7% 5% 3 4 5% 5% 5% 36%	1800
	21st to end	Day	15% 12% 3 7% 6% 3 4 4 4 6% 36%	1980
November	1st to 10th	Day	10% 8% 4 5% 5% 3 5% 4 5% 7% 44%	1857
	11th to 20th	Day	11% 11% 5% 10% 6% 3 5% 5% 6% 6% 31%	1578
	21st to end	Day	14% 12% 7% 8% 7% 4 5% 4 4 6% 28%	1520
December	1st to 10th	Day	15% 13% 7% 14% 7% 3 6% 5% 5% 5% 20%	1520
	11th to 20th	Day	13% 13% 7% 13% 7% 4 5% 4 4 5% 25%	1910
	21st to end	Day	15% 11% 9% 11% 7% 4 5% 5% 7% 6% 19%	2772
January	1st to 10th	Night	8% 11% 9% 19% 8% 4 6% 5% 5% 5% 20%	4109
	11th to 20th	Night	11% 11% 8% 15% 12% 4 6% 5% 4 5% 20%	4120
	21st to end	Night	17% 13% 6% 13% 10% 4 5% 4 4 4 19%	4532
February	1st to 10th	Night	11% 8% 5% 10% 8% 5% 6% 5% 7% 7% 29%	2470
	11th to 20th	Night	13% 9% 5% 11% 10% 4 7% 6% 5% 6% 24%	2403
	21st to end	Night	13% 11% 6% 10% 8% 4 4 5% 4 7% 27%	1853
March	1st to 10th	Night	18% 12% 5% 7% 6% 4 5% 5% 4 6% 28%	3418
	11th to 20th	Night	9% 10% 6% 11% 5% 3 5% 4 5% 8% 34%	3480
	21st to end	Night	12% 10% 4 7% 6% 3 5% 4 5% 5% 41%	3817
April	1st to 10th	Night	12% 10% 6% 9% 6% 4 5% 5% 4 6% 33%	1962
	11th to 20th	Night	11% 8% 4 8% 6% 4 6% 5% 5% 7% 37%	1775
	21st to end	Night	14% 9% 4 7% 6% 4 5% 4 4 6% 38%	1684
May	1st to 10th	Night	17% 8% 3 6% 5% 3 5% 5% 6% 8% 33%	1620
	11th to 20th	Night	19% 8% 3 6% 6% 3 5% 4 4 8% 34%	1592
	21st to end	Night	8% 7% 2 5% 6% 3 6% 6% 7% 10% 39%	1595
June	1st to 10th	Night	9% 7% 3 5% 6% 4 6% 5% 6% 8% 41%	1440
	11th to 20th	Night	11% 6% 3 6% 7% 4 4 6% 7% 9% 36%	1440
	21st to end	Night	9% 5% 3 6% 5% 4 5% 5% 7% 13% 38%	1440
July	1st to 10th	Night	9% 7% 3 5% 5% 3 5% 5% 7% 9% 41%	1512
	11th to 20th	Night	7% 5% 2 5% 7% 4 4 6% 5% 8% 47%	1620
	21st to end	Night	9% 5% 2 5% 7% 3 5% 7% 7% 10% 39%	1771
August	1st to 10th	Night	8% 6% 3 6% 6% 4 6% 5% 8% 9% 39%	1611
	11th to 20th	Night	9% 7% 2 5% 6% 5% 4 5% 5% 9% 43%	1598
	21st to end	Night	10% 5% 2 5% 6% 4 4 5% 5% 8% 46%	1934
September	1st to 10th	Night	12% 7% 2 6% 5% 3 4 5% 5% 7% 45%	1800
	11th to 20th	Night	10% 7% 2 6% 4 2 4 4 5% 7% 49%	1923
	21st to end	Night	15% 9% 3 6% 5% 4 5% 4 5% 7% 38%	2010
October	1st to 10th	Night	14% 8% 2 5% 5% 4 5% 5% 3 7% 42%	2160
	11th to 20th	Night	12% 10% 3 6% 5% 4 4 5% 6% 7% 39%	2160
	21st to end	Night	16% 11% 4 6% 6% 4 3 4 4 5% 37%	2376
November	1st to 10th	Night	9% 10% 4 6% 6% 3 5% 4 4 6% 44%	2221
	11th to 20th	Night	12% 10% 6% 8% 7% 4 5% 5% 5% 6% 32%	2597
	21st to end	Night	13% 10% 6% 9% 7% 3 6% 5% 5% 6% 30%	2660
December	1st to 10th	Night	15% 11% 7% 14% 7% 5% 6% 4 4 5% 22%	2660
	11th to 20th	Night	14% 9% 5% 13% 8% 5% 6% 5% 5% 6% 24%	3285
	21st to end	Night	14% 13% 8% 12% 7% 4 6% 6% 5% 6% 19%	4880

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	56% 12% 11% 14% 7% 1	2837
	11th to 20th	Day	67% 9% 7% 10% 6% 1	2840
	21st to end	Day	62% 11% 9% 13% 5% 1	3124
February	1st to 10th	Day	56% 10% 10% 15% 9%	1710
	11th to 20th	Day	57% 9% 11% 13% 10%	1672
	21st to end	Day	57% 9% 8% 14% 9% 2	1595
March	1st to 10th	Day	52% 8% 12% 20% 8% 1	3435
	11th to 20th	Day	41% 12% 11% 26% 10% 1	3480
	21st to end	Day	50% 8% 11% 19% 12% 1	3815
April	1st to 10th	Day	50% 9% 11% 16% 12% 2	2207
	11th to 20th	Day	47% 8% 11% 15% 16% 3	2134
	21st to end	Day	51% 8% 10% 20% 10% 2	2290
May	1st to 10th	Day	54% 9% 9% 16% 10% 1	2340
	11th to 20th	Day	53% 9% 10% 16% 9% 2	2305
	21st to end	Day	46% 11% 14% 20% 8% 1	2677
June	1st to 10th	Day	44% 11% 12% 21% 12% 1	2520
	11th to 20th	Day	46% 12% 11% 21% 9% 1	2520
	21st to end	Day	42% 11% 13% 23% 9% 1	2520
July	1st to 10th	Day	44% 11% 11% 20% 13% 2	2377
	11th to 20th	Day	42% 10% 13% 22% 12% 1	2271
	21st to end	Day	45% 12% 11% 19% 12% 1	2405
August	1st to 10th	Day	46% 13% 14% 18% 8%	2314
	11th to 20th	Day	45% 10% 13% 22% 10%	2303
	21st to end	Day	43% 11% 12% 21% 11% 2	2403
September	1st to 10th	Day	43% 8% 11% 18% 16% 3	2160
	11th to 20th	Day	40% 7% 11% 25% 14% 3	2034
	21st to end	Day	47% 7% 11% 20% 14% 1	1949
October	1st to 10th	Day	43% 9% 10% 22% 14% 3	1800
	11th to 20th	Day	49% 6% 10% 22% 13%	1800
	21st to end	Day	48% 8% 10% 20% 13% 2	1980
November	1st to 10th	Day	39% 8% 9% 22% 17% 5%	1857
	11th to 20th	Day	49% 9% 9% 15% 14% 3	1578
	21st to end	Day	55% 8% 11% 16% 10% 1	1520
December	1st to 10th	Day	64% 9% 9% 12% 5% 1	1520
	11th to 20th	Day	57% 9% 9% 19% 5% 1	1906
	21st to end	Day	58% 11% 13% 10% 7%	2772
January	1st to 10th	Night	60% 12% 8% 12% 7% 1	4109
	11th to 20th	Night	59% 11% 15% 11% 3	4120
	21st to end	Night	61% 12% 9% 12% 5% 1	4532
February	1st to 10th	Night	51% 12% 10% 17% 10% 1	2470
	11th to 20th	Night	58% 9% 10% 14% 9%	2405
	21st to end	Night	54% 10% 9% 16% 9% 3	1853
March	1st to 10th	Night	51% 10% 11% 20% 8% 1	3418
	11th to 20th	Night	44% 12% 11% 26% 6% 1	3480
	21st to end	Night	41% 9% 10% 24% 14% 2	3817
April	1st to 10th	Night	51% 8% 9% 17% 13% 2	1962
	11th to 20th	Night	44% 9% 12% 17% 14% 4	1775
	21st to end	Night	46% 8% 10% 24% 10% 3	1684
May	1st to 10th	Night	47% 9% 12% 19% 10% 3	1620
	11th to 20th	Night	48% 10% 11% 16% 14% 1	1593
	21st to end	Night	37% 12% 17% 24% 9% 1	1596
June	1st to 10th	Night	38% 11% 11% 25% 14% 1	1440
	11th to 20th	Night	42% 10% 13% 24% 10% 1	1440
	21st to end	Night	36% 12% 15% 23% 13% 1	1440
July	1st to 10th	Night	36% 14% 13% 23% 11% 3	1468
	11th to 20th	Night	34% 11% 14% 24% 15% 2	1566
	21st to end	Night	34% 13% 16% 23% 14% 1	1672
August	1st to 10th	Night	37% 11% 17% 23% 11% 1	1600
	11th to 20th	Night	36% 11% 14% 26% 13% 1	1598
	21st to end	Night	35% 10% 14% 25% 13% 2	1934
September	1st to 10th	Night	38% 9% 13% 21% 15% 4	1800
	11th to 20th	Night	33% 8% 12% 27% 18% 2	1923
	21st to end	Night	44% 8% 12% 20% 16%	2010
October	1st to 10th	Night	41% 9% 11% 24% 14% 2	2160
	11th to 20th	Night	41% 9% 10% 25% 15% 1	2160
	21st to end	Night	46% 8% 9% 22% 13% 2	2376
November	1st to 10th	Night	41% 8% 10% 20% 16% 6%	2221
	11th to 20th	Night	50% 8% 8% 18% 14% 2	2597
	21st to end	Night	53% 9% 10% 16% 10% 2	2660
December	1st to 10th	Night	61% 10% 9% 14% 4 2	2660
	11th to 20th	Night	56% 10% 10% 15% 8% 1	3288
	21st to end	Night	60% 12% 11% 11% 6%	4880

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	42% 27% 22% 6% 3	270
	11th to 20th	Day	43% 29% 23% 4 1	270
	21st to end	Day	35% 35% 24% 4 2	297
February	1st to 10th	Day	37% 29% 27% 6% 1	270
	11th to 20th	Day	50% 25% 23% 3	270
	21st to end	Day	41% 30% 23% 5% 1	307
March	1st to 10th	Day	34% 27% 26% 10% 2	460
	11th to 20th	Day	38% 27% 22% 10% 3 1	460
	21st to end	Day	34% 25% 26% 12% 2	506
April	1st to 10th	Day	31% 24% 28% 13% 4	457
	11th to 20th	Day	27% 21% 28% 14% 7% 3	412
	21st to end	Day	34% 25% 24% 11% 5% 1	420
May	1st to 10th	Day	34% 19% 27% 13% 4 3	423
	11th to 20th	Day	28% 21% 26% 17% 6% 3	447
	21st to end	Day	19% 16% 27% 21% 11% 6%	485
June	1st to 10th	Day	16% 18% 29% 22% 10% 4	450
	11th to 20th	Day	20% 16% 28% 19% 12% 4	450
	21st to end	Day	12% 17% 32% 24% 12% 3	450
July	1st to 10th	Day	13% 8% 29% 25% 16% 9%	445
	11th to 20th	Day	8% 10% 34% 28% 14% 7%	444
	21st to end	Day	15% 11% 27% 26% 14% 7%	488
August	1st to 10th	Day	12% 12% 26% 25% 17% 7%	446
	11th to 20th	Day	16% 10% 25% 25% 14% 10%	439
	21st to end	Day	13% 9% 28% 26% 15% 9%	495
September	1st to 10th	Day	17% 10% 24% 24% 16% 9%	450
	11th to 20th	Day	14% 8% 27% 24% 20% 7%	450
	21st to end	Day	25% 14% 26% 19% 12% 4	450
October	1st to 10th	Day	21% 13% 27% 24% 13% 2	450
	11th to 20th	Day	25% 20% 27% 20% 7%	450
	21st to end	Day	30% 24% 25% 15% 6%	495
November	1st to 10th	Day	23% 19% 29% 18% 9% 2	455
	11th to 20th	Day	29% 28% 28% 10% 5%	210
	21st to end	Day	35% 28% 26% 8% 2 1	180
December	1st to 10th	Day	39% 30% 21% 7% 2 2	180
	11th to 20th	Day	41% 27% 22% 8% 2	180
	21st to end	Day	37% 27% 22% 11% 3	198
January	1st to 10th	Night	33% 30% 24% 10% 3	760
	11th to 20th	Night	33% 30% 25% 12% 1	760
	21st to end	Night	34% 30% 25% 11% 1	836
February	1st to 10th	Night	31% 25% 28% 15% 1	760
	11th to 20th	Night	35% 34% 24% 7%	743
	21st to end	Night	32% 29% 27% 11% 1	628
March	1st to 10th	Night	29% 25% 27% 17% 2	760
	11th to 20th	Night	34% 23% 24% 14% 5% 1	760
	21st to end	Night	24% 25% 31% 15% 4 1	836
April	1st to 10th	Night	24% 26% 30% 17% 3	760
	11th to 20th	Night	21% 19% 30% 21% 8% 1	711
	21st to end	Night	25% 18% 26% 24% 6%	604
May	1st to 10th	Night	23% 16% 26% 27% 9%	540
	11th to 20th	Night	23% 13% 26% 25% 11% 1	531
	21st to end	Night	10% 11% 25% 29% 23% 2	435
June	1st to 10th	Night	11% 11% 25% 36% 16% 1	360
	11th to 20th	Night	14% 11% 24% 31% 19% 1	360
	21st to end	Night	11% 8% 32% 34% 14% 1	360
July	1st to 10th	Night	10% 9% 23% 33% 22% 4	418
	11th to 20th	Night	7% 8% 20% 36% 25% 4	522
	21st to end	Night	10% 8% 22% 34% 25% 2	591
August	1st to 10th	Night	10% 6% 19% 37% 25% 2	537
	11th to 20th	Night	11% 7% 16% 38% 24% 4	534
	21st to end	Night	11% 7% 20% 36% 23% 3	746
September	1st to 10th	Night	16% 6% 23% 31% 21% 4	720
	11th to 20th	Night	13% 8% 18% 34% 23% 3	720
	21st to end	Night	20% 13% 19% 28% 17% 2	720
October	1st to 10th	Night	19% 14% 22% 25% 18% 2	720
	11th to 20th	Night	22% 17% 27% 25% 9% 1	720
	21st to end	Night	28% 21% 24% 20% 6% 1	792
November	1st to 10th	Night	19% 18% 26% 26% 9% 1	740
	11th to 20th	Night	28% 21% 25% 18% 6% 1	760
	21st to end	Night	28% 22% 28% 18% 4 1	760
December	1st to 10th	Night	33% 24% 23% 14% 5%	760
	11th to 20th	Night	31% 28% 23% 16% 2	760
	21st to end	Night	30% 27% 26% 16% 2	836

Page generated at 2024-04-07 09:28:11. Version ac07

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