Bearbower Sand Prairie Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bearbower Sand Prairie Area clear sky chart from 2005-11-06 to 2024-11-12.

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	13% 8% 3 8% 5% 4 4 4 5% 7% 38%	101562
	Night	13% 9% 3 8% 5% 4 4 3 5% 6% 40%	97710
Transparency	Day	44% 6% 12% 23% 13% 1	105170
	Night	43% 5% 11% 23% 15% 2	102242
Seeing	Day	16% 10% 30% 26% 14% 4	15899
	Night	16% 9% 32% 31% 11% 1	25740

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	8% 13% 8% 19% 7% 7% 6% 3 4 5% 21%	2527
	11th to 20th	Day	10% 12% 4 11% 9% 8% 6% 5% 7% 6% 23%	2608
	21st to end	Day	14% 18% 6% 16% 6% 5% 4 3 5% 6% 16%	3135
February	1st to 10th	Day	11% 12% 5% 10% 6% 6% 4 4 5% 7% 29%	1710
	11th to 20th	Day	12% 11% 4 6% 5% 5% 6% 4 5% 6% 34%	1668
	21st to end	Day	14% 10% 4 9% 5% 4 4 5% 5% 6% 33%	1570
March	1st to 10th	Day	16% 10% 3 8% 5% 3 3 3 4 5% 41%	3278
	11th to 20th	Day	10% 7% 2 6% 5% 5% 4 4 5% 8% 43%	3480
	21st to end	Day	22% 14% 5% 11% 5% 4 5% 3 5% 6% 20%	3931
April	1st to 10th	Day	19% 12% 3 7% 4 4 4 4 5% 6% 32%	2280
	11th to 20th	Day	16% 12% 3 8% 5% 4 5% 3 5% 6% 33%	2254
	21st to end	Day	23% 8% 3 6% 4 4 3 3 5% 6% 34%	2316
May	1st to 10th	Day	20% 7% 2 7% 5% 5% 5% 4 6% 7% 33%	4234
	11th to 20th	Day	16% 7% 2 6% 4 4 4 4 5% 7% 42%	4399
	21st to end	Day	16% 6% 2 6% 5% 4 4 4 6% 8% 40%	4824
June	1st to 10th	Day	12% 5% 2 5% 4 5% 5% 4 7% 8% 44%	2660
	11th to 20th	Day	11% 6% 3 6% 3 3 4 4 6% 7% 45%	2660
	21st to end	Day	12% 6% 3 6% 5% 5% 4 5% 6% 9% 40%	2660
July	1st to 10th	Day	11% 7% 3 8% 5% 5% 5% 4 7% 9% 36%	4440
	11th to 20th	Day	5% 4 1 5% 3 4 4 4 6% 9% 55%	4440
	21st to end	Day	6% 5% 2 6% 5% 5% 5% 5% 8% 10% 44%	4698
August	1st to 10th	Day	8% 5% 2 7% 4 4 5% 5% 7% 8% 44%	4104
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 7% 10% 40%	3993
	21st to end	Day	8% 4 2 6% 4 4 4 3 6% 9% 49%	4180
September	1st to 10th	Day	14% 4 1 6% 3 3 4 2 5% 7% 49%	2280
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 4 7% 50%	2280
	21st to end	Day	11% 5% 2 6% 5% 4 4 4 5% 7% 47%	2003
October	1st to 10th	Day	15% 6% 2 6% 4 4 3 3 5% 6% 46%	1900
	11th to 20th	Day	18% 8% 2 5% 4 4 4 3 4 6% 42%	1900
	21st to end	Day	16% 10% 2 7% 4 3 4 3 4 5% 41%	2063
November	1st to 10th	Day	12% 7% 2 6% 5% 4 5% 3 4 7% 44%	1762
	11th to 20th	Day	13% 11% 6% 8% 4 4 4 4 5% 7% 35%	1584
	21st to end	Day	16% 10% 2 8% 4 4 3 3 5% 6% 38%	1520
December	1st to 10th	Day	13% 12% 5% 12% 5% 5% 4 3 4 6% 31%	1520
	11th to 20th	Day	14% 11% 4 9% 7% 6% 4 3 6% 7% 30%	1918
	21st to end	Day	22% 19% 8% 13% 4 3 4 2 4 4 16%	2783
January	1st to 10th	Night	10% 13% 8% 17% 6% 5% 4 3 4 5% 25%	4428
	11th to 20th	Night	12% 15% 5% 13% 7% 4 4 4 8% 6% 22%	4345
	21st to end	Night	16% 15% 6% 14% 6% 5% 4 3 4 6% 22%	4532
February	1st to 10th	Night	11% 12% 5% 9% 7% 5% 4 3 4 5% 34%	2470
	11th to 20th	Night	11% 10% 3 8% 5% 5% 4 3 5% 7% 40%	2397
	21st to end	Night	13% 11% 3 8% 5% 5% 5% 3 4 6% 38%	1884
March	1st to 10th	Night	16% 8% 3 7% 4 3 3 2 3 5% 45%	3605
	11th to 20th	Night	11% 6% 2 5% 4 4 3 3 5% 7% 50%	3480
	21st to end	Night	26% 11% 4 12% 5% 4 3 3 4 4 24%	3700
April	1st to 10th	Night	15% 10% 3 7% 5% 4 3 3 5% 5% 40%	1900
	11th to 20th	Night	16% 9% 2 6% 4 4 5% 4 4 6% 39%	1875
	21st to end	Night	18% 7% 2 6% 4 4 4 3 6% 6% 39%	1860
May	1st to 10th	Night	18% 8% 2 5% 4 4 4 4 5% 6% 39%	2668
	11th to 20th	Night	12% 7% 3 7% 4 4 4 3 5% 6% 45%	2506
	21st to end	Night	10% 7% 2 5% 4 4 4 4 5% 7% 46%	2743
June	1st to 10th	Night	8% 5% 2 6% 4 4 4 5% 7% 7% 48%	1520
	11th to 20th	Night	8% 5% 2 5% 4 5% 3 5% 8% 9% 45%	1520
	21st to end	Night	12% 4 2 5% 3 4 3 3 7% 8% 47%	1520
July	1st to 10th	Night	10% 6% 3 6% 4 4 5% 4 7% 9% 43%	2530
	11th to 20th	Night	4 2 2 4 3 3 4 4 5% 9% 60%	2530
	21st to end	Night	6% 4 2 6% 4 4 5% 4 6% 9% 50%	2862
August	1st to 10th	Night	6% 3 1 5% 3 4 4 4 7% 9% 53%	2836
	11th to 20th	Night	9% 5% 2 5% 4 4 3 3 5% 7% 53%	2842
	21st to end	Night	9% 5% 2 5% 4 3 4 3 5% 6% 53%	3476
September	1st to 10th	Night	10% 4 2 5% 4 3 3 3 5% 5% 55%	1900
	11th to 20th	Night	12% 4 2 5% 3 4 4 3 4 7% 53%	1900
	21st to end	Night	9% 5% 1 4 3 3 4 3 5% 6% 56%	2152
October	1st to 10th	Night	12% 6% 2 5% 4 3 3 3 4 6% 53%	2280
	11th to 20th	Night	15% 6% 2 6% 4 3 4 3 4 6% 47%	2280
	21st to end	Night	17% 9% 2 6% 5% 4 4 3 4 5% 40%	2533
November	1st to 10th	Night	12% 7% 2 5% 4 3 4 3 4 6% 50%	2536
	11th to 20th	Night	13% 10% 4 7% 5% 3 4 3 5% 7% 38%	2617
	21st to end	Night	16% 10% 2 7% 4 4 4 3 4 6% 41%	2660
December	1st to 10th	Night	13% 10% 4 10% 6% 4 4 4 5% 6% 33%	2660
	11th to 20th	Night	14% 12% 4 9% 6% 4 5% 3 5% 6% 33%	3279
	21st to end	Night	21% 16% 6% 12% 5% 5% 4 3 4 5% 19%	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	66% 6% 10% 11% 6%	2528
	11th to 20th	Day	59% 4 13% 15% 8%	2608
	21st to end	Day	69% 4 11% 11% 4	3135
February	1st to 10th	Day	54% 5% 13% 18% 9% 1	1710
	11th to 20th	Day	49% 6% 12% 23% 9% 1	1677
	21st to end	Day	50% 6% 13% 20% 9% 3	1570
March	1st to 10th	Day	46% 5% 10% 24% 13% 2	3278
	11th to 20th	Day	39% 6% 12% 29% 14% 1	3480
	21st to end	Day	64% 6% 12% 13% 4 1	3931
April	1st to 10th	Day	53% 5% 11% 22% 8%	2280
	11th to 20th	Day	50% 6% 10% 21% 12% 1	2254
	21st to end	Day	50% 5% 11% 20% 12% 2	2316
May	1st to 10th	Day	49% 7% 12% 18% 13% 1	4272
	11th to 20th	Day	41% 7% 12% 28% 12%	4403
	21st to end	Day	40% 8% 11% 23% 16% 1	4837
June	1st to 10th	Day	35% 9% 14% 24% 16% 2	2660
	11th to 20th	Day	36% 7% 12% 22% 21% 3	2660
	21st to end	Day	40% 8% 13% 23% 13% 2	2660
July	1st to 10th	Day	43% 7% 13% 27% 9% 1	4371
	11th to 20th	Day	27% 7% 15% 32% 18% 2	4365
	21st to end	Day	33% 11% 18% 20% 18% 2	4550
August	1st to 10th	Day	35% 8% 15% 27% 13% 2	4090
	11th to 20th	Day	38% 7% 16% 24% 14% 1	4032
	21st to end	Day	32% 6% 14% 30% 17% 2	4179
September	1st to 10th	Day	34% 5% 12% 25% 21% 3	2280
	11th to 20th	Day	33% 6% 12% 31% 17% 1	2280
	21st to end	Day	36% 5% 10% 30% 17% 1	2003
October	1st to 10th	Day	23% 4 6% 33% 33% 1	3160
	11th to 20th	Day	31% 2 11% 28% 24% 5%	3140
	21st to end	Day	41% 4 10% 29% 14% 3	3377
November	1st to 10th	Day	40% 5% 13% 26% 13% 3	1762
	11th to 20th	Day	49% 5% 15% 19% 12% 1	1584
	21st to end	Day	47% 6% 16% 23% 9%	1520
December	1st to 10th	Day	55% 6% 12% 18% 8% 2	1520
	11th to 20th	Day	53% 5% 17% 16% 9% 1	1915
	21st to end	Day	72% 4 10% 9% 4	2783
January	1st to 10th	Night	60% 5% 12% 15% 8% 1	4428
	11th to 20th	Night	60% 3 12% 15% 9%	4345
	21st to end	Night	65% 5% 10% 14% 5% 1	4532
February	1st to 10th	Night	52% 4 10% 21% 12% 1	2470
	11th to 20th	Night	44% 5% 12% 25% 13% 2	2398
	21st to end	Night	48% 4 12% 20% 14% 2	1884
March	1st to 10th	Night	43% 4 10% 26% 16% 2	3605
	11th to 20th	Night	34% 5% 11% 32% 17% 2	3480
	21st to end	Night	65% 5% 11% 13% 5% 1	3700
April	1st to 10th	Night	46% 4 9% 25% 13% 2	1900
	11th to 20th	Night	46% 5% 8% 21% 16% 3	1875
	21st to end	Night	44% 5% 11% 24% 14% 2	1860
May	1st to 10th	Night	44% 6% 11% 16% 21% 2	2695
	11th to 20th	Night	39% 6% 10% 28% 14% 3	2507
	21st to end	Night	34% 7% 12% 27% 18% 2	2751
June	1st to 10th	Night	31% 8% 16% 26% 16% 3	1520
	11th to 20th	Night	32% 8% 13% 23% 20% 4	1520
	21st to end	Night	33% 7% 15% 26% 15% 4	1520
July	1st to 10th	Night	37% 6% 15% 27% 12% 2	2490
	11th to 20th	Night	21% 6% 17% 36% 17% 2	2482
	21st to end	Night	30% 9% 16% 23% 20% 2	2771
August	1st to 10th	Night	27% 6% 17% 33% 16% 2	2826
	11th to 20th	Night	30% 6% 14% 35% 14% 1	2869
	21st to end	Night	31% 6% 12% 27% 19% 5%	3476
September	1st to 10th	Night	31% 6% 9% 26% 26% 2	1900
	11th to 20th	Night	32% 5% 9% 32% 20% 2	1900
	21st to end	Night	29% 6% 10% 30% 23% 2	2152
October	1st to 10th	Night	23% 3 6% 29% 36% 3	3800
	11th to 20th	Night	28% 3 10% 23% 30% 6%	3779
	21st to end	Night	47% 4 8% 23% 15% 3	4169
November	1st to 10th	Night	36% 4 13% 25% 18% 3	2536
	11th to 20th	Night	46% 4 12% 24% 12% 1	2617
	21st to end	Night	46% 4 12% 26% 11% 1	2660
December	1st to 10th	Night	51% 5% 12% 22% 8% 1	2660
	11th to 20th	Night	52% 5% 13% 23% 6% 1	3281
	21st to end	Night	68% 5% 8% 13% 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	18% 13% 34% 25% 8% 2	270
	11th to 20th	Day	17% 13% 43% 21% 4	270
	21st to end	Day	20% 15% 33% 26% 5% 1	297
February	1st to 10th	Day	16% 20% 38% 22% 4	270
	11th to 20th	Day	19% 19% 32% 22% 7%	270
	21st to end	Day	20% 15% 43% 17% 5%	225
March	1st to 10th	Day	15% 19% 41% 19% 5% 1	270
	11th to 20th	Day	20% 16% 33% 21% 8% 2	270
	21st to end	Day	31% 16% 30% 16% 6% 1	363
April	1st to 10th	Day	25% 14% 39% 17% 5%	460
	11th to 20th	Day	24% 18% 28% 21% 8% 1	452
	21st to end	Day	25% 14% 34% 16% 9% 2	496
May	1st to 10th	Day	23% 13% 32% 23% 8% 1	653
	11th to 20th	Day	20% 13% 27% 25% 12% 3	675
	21st to end	Day	16% 11% 29% 25% 15% 4	734
June	1st to 10th	Day	10% 5% 29% 31% 20% 5%	680
	11th to 20th	Day	13% 6% 29% 33% 17% 3	680
	21st to end	Day	11% 8% 33% 31% 13% 4	680
July	1st to 10th	Day	9% 3 18% 35% 22% 13%	671
	11th to 20th	Day	8% 3 26% 31% 24% 8%	668
	21st to end	Day	6% 3 24% 36% 26% 4	739
August	1st to 10th	Day	7% 4 24% 32% 27% 8%	676
	11th to 20th	Day	12% 5% 20% 31% 23% 10%	643
	21st to end	Day	8% 4 22% 34% 24% 8%	539
September	1st to 10th	Day	15% 5% 22% 31% 21% 6%	490
	11th to 20th	Day	9% 4 23% 36% 21% 7%	490
	21st to end	Day	13% 11% 29% 27% 17% 3	358
October	1st to 10th	Day	18% 9% 29% 25% 15% 4	300
	11th to 20th	Day	25% 18% 32% 16% 8% 1	300
	21st to end	Day	21% 18% 36% 18% 5% 2	330
November	1st to 10th	Day	17% 11% 38% 23% 9% 3	300
	11th to 20th	Day	16% 23% 27% 26% 8% 1	273
	21st to end	Day	26% 11% 35% 23% 5%	270
December	1st to 10th	Day	13% 13% 43% 22% 7% 2	270
	11th to 20th	Day	18% 13% 35% 23% 9% 1	270
	21st to end	Day	26% 19% 37% 16% 2	297
January	1st to 10th	Night	14% 14% 37% 27% 7%	950
	11th to 20th	Night	16% 14% 36% 28% 6%	950
	21st to end	Night	19% 12% 34% 29% 5%	1045
February	1st to 10th	Night	17% 12% 38% 27% 6%	950
	11th to 20th	Night	16% 12% 38% 28% 6%	923
	21st to end	Night	18% 13% 39% 25% 4 1	628
March	1st to 10th	Night	20% 13% 37% 24% 6% 1	684
	11th to 20th	Night	17% 10% 35% 28% 9% 1	570
	21st to end	Night	24% 11% 36% 22% 6% 1	627
April	1st to 10th	Night	20% 12% 41% 24% 3	570
	11th to 20th	Night	20% 13% 35% 25% 6%	563
	21st to end	Night	20% 10% 35% 26% 8% 1	570
May	1st to 10th	Night	18% 10% 34% 31% 7% 1	570
	11th to 20th	Night	17% 9% 30% 34% 10% 1	561
	21st to end	Night	15% 5% 31% 33% 15% 2	617
June	1st to 10th	Night	9% 5% 28% 42% 15% 1	570
	11th to 20th	Night	10% 3 32% 42% 13% 1	570
	21st to end	Night	12% 4 28% 39% 15% 1	570
July	1st to 10th	Night	6% 1 15% 44% 30% 3	555
	11th to 20th	Night	5% 2 19% 44% 27% 3	552
	21st to end	Night	7% 1 20% 48% 22% 2	624
August	1st to 10th	Night	6% 2 15% 48% 27% 2	567
	11th to 20th	Night	9% 3 16% 43% 25% 4	564
	21st to end	Night	10% 2 17% 43% 24% 3	627
September	1st to 10th	Night	11% 4 20% 40% 21% 4	570
	11th to 20th	Night	12% 3 21% 37% 25% 2	570
	21st to end	Night	10% 7% 29% 35% 18% 1	694
October	1st to 10th	Night	15% 6% 29% 35% 14% 1	760
	11th to 20th	Night	18% 11% 34% 29% 8%	760
	21st to end	Night	21% 11% 31% 28% 8%	836
November	1st to 10th	Night	16% 9% 38% 28% 8%	780
	11th to 20th	Night	17% 13% 40% 23% 7%	898
	21st to end	Night	20% 11% 37% 24% 8%	950
December	1st to 10th	Night	17% 13% 39% 25% 6% 1	950
	11th to 20th	Night	22% 9% 35% 27% 6%	950
	21st to end	Night	26% 12% 35% 23% 4	1045

Page generated at 2024-11-08 21:45:40. Version ac07

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