Powhatan Wildlife Management Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Powhatan Wildlife Management Area 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% 6% 2 5% 5% 3 5% 5% 5% 8% 43%	78799
	Night	14% 6% 2 5% 5% 3 4 4 5% 7% 45%	81069
Transparency	Day	39% 6% 12% 23% 17% 4	78520
	Night	39% 6% 10% 22% 18% 4	80867
Seeing	Day	19% 11% 26% 24% 15% 5%	14208
	Night	17% 10% 27% 31% 14% 2	24073

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	18% 4 2 4 3 2 4 3 4 5% 52%	2836
	11th to 20th	Day	15% 8% 2 5% 5% 3 4 3 5% 5% 45%	2840
	21st to end	Day	18% 9% 3 6% 5% 3 3 4 4 5% 40%	3124
February	1st to 10th	Day	13% 7% 3 6% 5% 3 5% 5% 5% 7% 41%	1710
	11th to 20th	Day	21% 6% 2 4 4 2 4 4 5% 5% 43%	1696
	21st to end	Day	19% 6% 3 6% 5% 4 4 4 5% 7% 36%	1613
March	1st to 10th	Day	14% 6% 2 4 3 3 4 4 5% 6% 49%	2090
	11th to 20th	Day	16% 6% 3 5% 5% 3 4 4 6% 7% 42%	2090
	21st to end	Day	17% 6% 3 6% 6% 4 4 4 5% 7% 39%	2200
April	1st to 10th	Day	10% 5% 2 4 4 2 4 5% 5% 7% 52%	2146
	11th to 20th	Day	12% 5% 3 5% 5% 2 4 3 5% 7% 49%	2134
	21st to end	Day	16% 6% 3 5% 5% 3 5% 4 5% 7% 42%	2160
May	1st to 10th	Day	14% 6% 3 5% 5% 3 5% 5% 6% 8% 40%	2308
	11th to 20th	Day	17% 7% 3 5% 5% 4 4 5% 5% 7% 39%	2301
	21st to end	Day	14% 5% 2 5% 5% 3 5% 6% 6% 10% 40%	2677
June	1st to 10th	Day	10% 3 2 5% 5% 3 5% 5% 7% 11% 44%	2520
	11th to 20th	Day	11% 4 2 5% 6% 3 6% 5% 8% 9% 41%	2520
	21st to end	Day	8% 4 2 4 6% 3 6% 7% 7% 10% 43%	2520
July	1st to 10th	Day	9% 6% 2 6% 6% 4 5% 6% 7% 10% 41%	2424
	11th to 20th	Day	5% 4 2 5% 6% 4 6% 7% 8% 12% 42%	2340
	21st to end	Day	8% 4 3 5% 7% 4 8% 7% 8% 11% 37%	2547
August	1st to 10th	Day	11% 6% 3 6% 6% 4 6% 6% 7% 10% 35%	2327
	11th to 20th	Day	11% 5% 3 7% 6% 4 6% 7% 8% 10% 34%	2222
	21st to end	Day	10% 5% 2 6% 6% 3 6% 5% 7% 10% 39%	2376
September	1st to 10th	Day	12% 6% 2 5% 5% 4 4 5% 5% 8% 45%	2160
	11th to 20th	Day	12% 6% 2 5% 4 3 4 4 5% 8% 46%	2127
	21st to end	Day	19% 6% 2 6% 5% 3 4 4 5% 7% 39%	1895
October	1st to 10th	Day	16% 5% 2 5% 4 3 3 4 4 6% 48%	1800
	11th to 20th	Day	17% 4 2 3 4 2 3 4 4 6% 51%	1800
	21st to end	Day	13% 5% 2 5% 4 2 3 3 3 6% 52%	1980
November	1st to 10th	Day	13% 4 2 3 4 3 3 3 4 5% 55%	1857
	11th to 20th	Day	15% 5% 2 4 4 2 3 3 5% 6% 50%	1723
	21st to end	Day	14% 4 3 4 3 3 3 3 5% 6% 52%	1520
December	1st to 10th	Day	17% 6% 3 5% 4 3 5% 4 6% 7% 40%	1520
	11th to 20th	Day	16% 5% 2 4 3 2 4 3 3 5% 52%	1910
	21st to end	Day	18% 6% 2 5% 4 3 4 5% 5% 7% 39%	2786
January	1st to 10th	Night	14% 7% 3 5% 4 3 4 4 5% 5% 47%	4109
	11th to 20th	Night	18% 7% 3 4 4 2 3 4 4 5% 47%	4120
	21st to end	Night	21% 8% 3 5% 4 2 3 4 4 4 43%	4532
February	1st to 10th	Night	14% 7% 2 5% 5% 3 4 5% 5% 7% 44%	2470
	11th to 20th	Night	19% 6% 2 4 5% 3 4 4 4 6% 43%	2369
	21st to end	Night	17% 6% 2 5% 5% 2 4 4 5% 5% 45%	1837
March	1st to 10th	Night	14% 5% 2 4 3 2 4 3 5% 6% 51%	2090
	11th to 20th	Night	17% 5% 2 6% 5% 3 4 4 6% 7% 41%	2090
	21st to end	Night	15% 6% 3 6% 5% 3 4 5% 4 6% 43%	2201
April	1st to 10th	Night	13% 6% 4 5% 5% 3 4 4 5% 6% 47%	1813
	11th to 20th	Night	11% 6% 2 4 4 3 4 4 5% 8% 49%	1775
	21st to end	Night	15% 6% 2 4 4 3 5% 4 6% 7% 45%	1800
May	1st to 10th	Night	14% 5% 3 5% 5% 3 5% 4 6% 8% 42%	1667
	11th to 20th	Night	15% 6% 3 5% 5% 4 5% 5% 6% 7% 40%	1592
	21st to end	Night	13% 5% 2 5% 5% 3 5% 6% 6% 9% 42%	1594
June	1st to 10th	Night	12% 3 2 5% 4 3 5% 5% 7% 9% 43%	1440
	11th to 20th	Night	10% 5% 3 6% 5% 3 7% 5% 7% 10% 41%	1440
	21st to end	Night	9% 5% 2 4 5% 3 5% 5% 7% 12% 43%	1440
July	1st to 10th	Night	9% 5% 3 6% 5% 4 4 6% 6% 9% 42%	1531
	11th to 20th	Night	4 4 2 5% 6% 3 7% 6% 7% 12% 45%	1620
	21st to end	Night	6% 5% 2 5% 6% 4 8% 8% 7% 10% 39%	1771
August	1st to 10th	Night	9% 5% 2 6% 6% 4 6% 7% 7% 10% 38%	1611
	11th to 20th	Night	12% 6% 2 7% 5% 4 6% 6% 6% 9% 37%	1660
	21st to end	Night	8% 6% 2 6% 8% 5% 5% 6% 7% 9% 38%	1980
September	1st to 10th	Night	14% 6% 2 4 6% 3 4 4 5% 8% 43%	1800
	11th to 20th	Night	11% 5% 3 5% 5% 3 5% 5% 5% 7% 47%	1829
	21st to end	Night	21% 8% 2 5% 4 2 4 5% 5% 5% 39%	2064
October	1st to 10th	Night	16% 6% 3 5% 4 3 4 4 4 5% 46%	2160
	11th to 20th	Night	16% 5% 2 4 4 2 3 4 4 6% 48%	2160
	21st to end	Night	13% 5% 2 5% 4 3 4 4 4 6% 51%	2376
November	1st to 10th	Night	13% 7% 2 4 4 3 3 4 4 5% 51%	2221
	11th to 20th	Night	14% 6% 2 4 4 2 4 4 4 6% 51%	2450
	21st to end	Night	13% 4 2 4 4 2 5% 4 5% 7% 50%	2660
December	1st to 10th	Night	17% 8% 3 5% 5% 3 4 4 4 5% 43%	2660
	11th to 20th	Night	17% 7% 2 4 4 2 3 3 4 5% 48%	3285
	21st to end	Night	16% 7% 2 5% 4 3 5% 5% 5% 7% 41%	4852

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	36% 4 6% 32% 17% 5%	2837
	11th to 20th	Day	40% 5% 7% 20% 22% 6%	2840
	21st to end	Day	47% 4 9% 21% 15% 3	3124
February	1st to 10th	Day	42% 6% 9% 26% 14% 3	1710
	11th to 20th	Day	42% 5% 7% 22% 20% 5%	1705
	21st to end	Day	47% 5% 12% 14% 17% 5%	1613
March	1st to 10th	Day	36% 6% 9% 23% 21% 6%	2090
	11th to 20th	Day	41% 5% 10% 20% 17% 8%	2090
	21st to end	Day	47% 6% 8% 19% 17% 4	2200
April	1st to 10th	Day	31% 5% 12% 23% 20% 9%	2146
	11th to 20th	Day	35% 4 11% 21% 22% 7%	2134
	21st to end	Day	41% 5% 11% 21% 16% 5%	2160
May	1st to 10th	Day	40% 8% 15% 19% 15% 3	2308
	11th to 20th	Day	44% 7% 13% 22% 11% 2	2305
	21st to end	Day	39% 8% 16% 25% 12%	2677
June	1st to 10th	Day	33% 8% 17% 25% 15% 1	2520
	11th to 20th	Day	37% 10% 16% 21% 16% 2	2520
	21st to end	Day	33% 10% 16% 25% 15% 2	2520
July	1st to 10th	Day	38% 9% 14% 20% 17% 3	2359
	11th to 20th	Day	32% 9% 21% 24% 13% 2	2271
	21st to end	Day	36% 10% 15% 23% 15% 1	2405
August	1st to 10th	Day	42% 9% 16% 22% 11% 1	2314
	11th to 20th	Day	41% 11% 15% 21% 10% 1	2222
	21st to end	Day	37% 8% 16% 23% 13% 3	2376
September	1st to 10th	Day	37% 7% 14% 17% 20% 4	2160
	11th to 20th	Day	37% 7% 8% 24% 20% 4	2127
	21st to end	Day	46% 4 9% 20% 17% 4	1895
October	1st to 10th	Day	38% 4 11% 24% 20% 4	1800
	11th to 20th	Day	34% 5% 8% 24% 24% 5%	1800
	21st to end	Day	34% 4 6% 26% 24% 6%	1980
November	1st to 10th	Day	33% 4 8% 24% 27% 5%	1857
	11th to 20th	Day	36% 3 9% 21% 22% 8%	1723
	21st to end	Day	34% 5% 8% 23% 25% 5%	1520
December	1st to 10th	Day	42% 5% 11% 23% 15% 4	1520
	11th to 20th	Day	36% 4 7% 29% 17% 7%	1906
	21st to end	Day	43% 6% 10% 26% 14% 2	2786
January	1st to 10th	Night	38% 4 8% 23% 22% 5%	4109
	11th to 20th	Night	40% 4 7% 21% 23% 5%	4120
	21st to end	Night	45% 4 6% 22% 16% 6%	4532
February	1st to 10th	Night	40% 5% 10% 24% 18% 3	2470
	11th to 20th	Night	43% 4 7% 20% 19% 7%	2371
	21st to end	Night	41% 4 8% 22% 18% 7%	1837
March	1st to 10th	Night	36% 4 9% 25% 23% 4	2090
	11th to 20th	Night	42% 5% 8% 21% 20% 5%	2090
	21st to end	Night	43% 5% 9% 21% 17% 5%	2201
April	1st to 10th	Night	39% 6% 9% 17% 22% 7%	1813
	11th to 20th	Night	33% 5% 11% 22% 22% 7%	1775
	21st to end	Night	39% 5% 12% 23% 16% 6%	1800
May	1st to 10th	Night	39% 8% 14% 21% 14% 4	1667
	11th to 20th	Night	43% 8% 13% 21% 13% 2	1593
	21st to end	Night	37% 10% 14% 26% 11% 1	1595
June	1st to 10th	Night	35% 8% 13% 27% 15% 1	1440
	11th to 20th	Night	37% 10% 17% 19% 15% 2	1440
	21st to end	Night	33% 9% 15% 21% 18% 4	1440
July	1st to 10th	Night	38% 10% 15% 17% 15% 4	1486
	11th to 20th	Night	30% 11% 21% 24% 12% 2	1566
	21st to end	Night	36% 11% 17% 23% 13% 1	1672
August	1st to 10th	Night	39% 10% 15% 24% 11% 1	1600
	11th to 20th	Night	42% 9% 17% 20% 12% 1	1660
	21st to end	Night	39% 10% 14% 23% 10% 3	1980
September	1st to 10th	Night	39% 7% 15% 18% 16% 5%	1800
	11th to 20th	Night	37% 6% 10% 22% 22% 3	1829
	21st to end	Night	46% 6% 10% 19% 16% 4	2064
October	1st to 10th	Night	39% 6% 9% 23% 19% 4	2160
	11th to 20th	Night	37% 4 8% 23% 22% 5%	2160
	21st to end	Night	35% 4 9% 23% 23% 6%	2376
November	1st to 10th	Night	35% 5% 8% 21% 25% 6%	2221
	11th to 20th	Night	36% 5% 8% 20% 23% 9%	2450
	21st to end	Night	33% 5% 8% 25% 22% 6%	2660
December	1st to 10th	Night	43% 5% 8% 23% 17% 4	2660
	11th to 20th	Night	39% 4 8% 22% 21% 7%	3288
	21st to end	Night	40% 7% 11% 24% 16% 2	4852

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	28% 21% 27% 17% 6%	270
	11th to 20th	Day	28% 26% 32% 11% 3	270
	21st to end	Day	28% 17% 39% 12% 3	297
February	1st to 10th	Day	24% 21% 37% 14% 4	270
	11th to 20th	Day	37% 23% 29% 8% 2	303
	21st to end	Day	30% 17% 30% 19% 3	382
March	1st to 10th	Day	22% 22% 31% 20% 6%	460
	11th to 20th	Day	23% 22% 33% 16% 5% 1	460
	21st to end	Day	24% 17% 35% 17% 6% 1	470
April	1st to 10th	Day	23% 19% 28% 20% 8% 1	420
	11th to 20th	Day	20% 12% 33% 21% 9% 5%	412
	21st to end	Day	24% 12% 34% 20% 8% 2	420
May	1st to 10th	Day	22% 13% 32% 21% 8% 3	423
	11th to 20th	Day	23% 7% 28% 25% 13% 4	447
	21st to end	Day	19% 4 20% 30% 21% 5%	485
June	1st to 10th	Day	11% 5% 26% 30% 22% 6%	450
	11th to 20th	Day	12% 7% 24% 31% 18% 9%	450
	21st to end	Day	11% 5% 23% 32% 21% 7%	450
July	1st to 10th	Day	10% 4 18% 29% 28% 11%	445
	11th to 20th	Day	5% 2 16% 34% 30% 12%	444
	21st to end	Day	9% 3 21% 31% 24% 10%	488
August	1st to 10th	Day	12% 4 19% 28% 28% 9%	446
	11th to 20th	Day	13% 3 14% 30% 29% 12%	439
	21st to end	Day	10% 3 16% 28% 26% 16%	495
September	1st to 10th	Day	16% 5% 17% 25% 22% 16%	450
	11th to 20th	Day	14% 4 16% 32% 23% 12%	450
	21st to end	Day	26% 8% 20% 27% 13% 5%	450
October	1st to 10th	Day	23% 5% 22% 23% 18% 8%	450
	11th to 20th	Day	18% 10% 21% 29% 19% 3	450
	21st to end	Day	16% 12% 33% 25% 10% 4	495
November	1st to 10th	Day	18% 10% 28% 26% 15% 4	455
	11th to 20th	Day	19% 12% 30% 25% 12% 2	368
	21st to end	Day	21% 15% 28% 25% 8% 3	180
December	1st to 10th	Day	24% 15% 38% 14% 8% 2	180
	11th to 20th	Day	24% 14% 31% 22% 7% 1	180
	21st to end	Day	29% 14% 29% 17% 9% 2	204
January	1st to 10th	Night	20% 18% 35% 23% 3	760
	11th to 20th	Night	22% 17% 31% 27% 4	760
	21st to end	Night	21% 15% 38% 24% 3	836
February	1st to 10th	Night	21% 14% 36% 26% 3	760
	11th to 20th	Night	25% 17% 37% 18% 2	743
	21st to end	Night	24% 16% 35% 23% 3	628
March	1st to 10th	Night	19% 15% 36% 27% 3	760
	11th to 20th	Night	22% 16% 34% 21% 6%	760
	21st to end	Night	18% 14% 39% 24% 5%	801
April	1st to 10th	Night	17% 16% 36% 25% 5%	720
	11th to 20th	Night	13% 13% 36% 28% 9% 1	711
	21st to end	Night	18% 8% 33% 33% 8%	720
May	1st to 10th	Night	18% 8% 32% 33% 8% 1	587
	11th to 20th	Night	18% 5% 25% 35% 15% 1	531
	21st to end	Night	14% 3 17% 41% 24% 2	434
June	1st to 10th	Night	11% 3 18% 45% 23% 1	360
	11th to 20th	Night	11% 3 19% 39% 25% 3	360
	21st to end	Night	9% 2 21% 44% 22% 1	360
July	1st to 10th	Night	12% 3 13% 38% 30% 3	436
	11th to 20th	Night	5% 1 10% 42% 37% 5%	522
	21st to end	Night	7% 2 16% 43% 27% 4	591
August	1st to 10th	Night	11% 2 12% 43% 29% 3	537
	11th to 20th	Night	14% 2 10% 40% 30% 4	596
	21st to end	Night	10% 3 14% 34% 33% 6%	792
September	1st to 10th	Night	16% 3 12% 34% 29% 6%	720
	11th to 20th	Night	13% 4 15% 33% 31% 4	720
	21st to end	Night	23% 4 18% 34% 19% 1	720
October	1st to 10th	Night	19% 4 19% 33% 21% 4	720
	11th to 20th	Night	18% 7% 27% 29% 18% 1	720
	21st to end	Night	17% 9% 28% 30% 14% 1	792
November	1st to 10th	Night	17% 8% 27% 33% 14% 2	740
	11th to 20th	Night	17% 12% 30% 30% 10% 1	760
	21st to end	Night	14% 13% 31% 32% 9% 1	760
December	1st to 10th	Night	22% 13% 32% 26% 8%	760
	11th to 20th	Night	19% 11% 33% 32% 6%	760
	21st to end	Night	22% 14% 26% 33% 4	836

Page generated at 2024-03-19 23:31:08. Version ac07

Copyright © 2024 Attilla Danko.