Little Bow Reservoir
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Bow Reservoir clear sky chart from 2005-11-06 to 2024-11-08.

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	8% 8% 3 7% 5% 5% 5% 4 6% 8% 42%	105579
	Night	7% 9% 3 8% 5% 5% 5% 4 6% 8% 40%	102092
Transparency	Day	37% 7% 15% 26% 12% 2	105323
	Night	40% 8% 15% 24% 12% 2	101994
Seeing	Day	11% 9% 25% 29% 19% 6%	15431
	Night	11% 9% 31% 33% 15% 2	24535

By Month

Percentage Cloud Cover NW (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	4 12% 5% 10% 5% 5% 5% 5% 7% 10% 31%	2219
	11th to 20th	Day	4 8% 4 13% 7% 6% 6% 6% 8% 7% 31%	2213
	21st to end	Day	4 8% 4 11% 6% 6% 4 4 5% 8% 40%	2794
February	1st to 10th	Day	7% 13% 4 10% 8% 6% 7% 5% 5% 8% 28%	1583
	11th to 20th	Day	6% 12% 5% 11% 7% 6% 6% 6% 6% 7% 29%	1665
	21st to end	Day	4 13% 6% 11% 8% 5% 4 4 6% 8% 29%	1494
March	1st to 10th	Day	3 11% 4 11% 8% 7% 6% 5% 6% 8% 31%	3169
	11th to 20th	Day	7% 8% 2 7% 5% 5% 4 3 5% 8% 45%	3489
	21st to end	Day	9% 19% 6% 13% 6% 4 4 4 5% 7% 23%	3825
April	1st to 10th	Day	9% 12% 4 9% 6% 5% 5% 4 6% 7% 31%	2333
	11th to 20th	Day	10% 12% 3 8% 5% 5% 6% 5% 7% 7% 32%	2440
	21st to end	Day	10% 10% 3 8% 6% 5% 5% 5% 6% 8% 34%	2470
May	1st to 10th	Day	18% 12% 4 7% 4 4 4 4 5% 6% 31%	4223
	11th to 20th	Day	9% 7% 3 7% 6% 5% 7% 6% 8% 10% 33%	4690
	21st to end	Day	13% 8% 3 9% 6% 6% 7% 5% 7% 8% 28%	5161
June	1st to 10th	Day	12% 8% 3 6% 5% 5% 6% 5% 7% 9% 35%	2850
	11th to 20th	Day	15% 9% 2 8% 5% 4 5% 5% 7% 8% 32%	2850
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 7% 9% 47%	2850
July	1st to 10th	Day	5% 4 2 4 4 4 4 4 6% 8% 56%	4740
	11th to 20th	Day	4 3 1 4 3 3 4 3 6% 10% 58%	4740
	21st to end	Day	3 2 1 3 2 2 3 3 5% 8% 68%	5052
August	1st to 10th	Day	8% 5% 2 5% 3 4 4 4 7% 10% 48%	4321
	11th to 20th	Day	5% 4 2 5% 3 3 5% 5% 7% 9% 51%	4028
	21st to end	Day	8% 3 1 4 3 3 3 4 5% 8% 57%	4521
September	1st to 10th	Day	10% 5% 2 4 4 3 3 3 4 7% 56%	2353
	11th to 20th	Day	14% 7% 2 5% 3 3 3 3 6% 7% 47%	2090
	21st to end	Day	8% 7% 2 6% 3 5% 4 3 5% 8% 49%	2090
October	1st to 10th	Day	8% 7% 3 7% 5% 4 5% 4 7% 8% 42%	3298
	11th to 20th	Day	6% 6% 2 6% 4 5% 5% 4 6% 8% 48%	3015
	21st to end	Day	7% 7% 2 6% 5% 4 5% 4 6% 8% 46%	3101
November	1st to 10th	Day	10% 15% 3 8% 5% 5% 4 4 7% 7% 31%	1589
	11th to 20th	Day	6% 10% 3 8% 6% 4 4 3 6% 9% 39%	1520
	21st to end	Day	4 11% 5% 9% 5% 4 5% 4 7% 9% 36%	1349
December	1st to 10th	Day	5% 14% 4 10% 6% 5% 5% 4 6% 7% 34%	1330
	11th to 20th	Day	4 11% 5% 12% 7% 6% 5% 4 7% 7% 32%	1682
	21st to end	Day	4 8% 3 7% 5% 5% 5% 4 6% 8% 44%	2442
January	1st to 10th	Night	4 11% 5% 11% 7% 6% 6% 5% 7% 9% 29%	4726
	11th to 20th	Night	4 9% 5% 14% 6% 5% 6% 5% 6% 8% 33%	4699
	21st to end	Night	4 9% 4 10% 6% 5% 5% 4 6% 7% 41%	4863
February	1st to 10th	Night	7% 11% 4 11% 7% 7% 6% 4 5% 7% 31%	2596
	11th to 20th	Night	5% 14% 5% 11% 6% 7% 6% 5% 7% 8% 28%	2402
	21st to end	Night	4 13% 5% 10% 7% 6% 6% 4 6% 8% 33%	1957
March	1st to 10th	Night	3 10% 5% 13% 7% 6% 6% 5% 7% 7% 31%	3705
	11th to 20th	Night	7% 8% 3 6% 4 4 6% 4 6% 8% 44%	3490
	21st to end	Night	11% 19% 6% 12% 6% 4 5% 3 6% 7% 21%	3828
April	1st to 10th	Night	8% 13% 3 9% 6% 5% 5% 4 7% 9% 31%	1843
	11th to 20th	Night	9% 12% 5% 8% 5% 5% 5% 4 6% 8% 32%	1691
	21st to end	Night	10% 10% 3 7% 6% 6% 4 5% 7% 7% 34%	1710
May	1st to 10th	Night	17% 13% 4 9% 5% 4 5% 4 5% 6% 29%	2746
	11th to 20th	Night	8% 6% 2 7% 5% 6% 6% 5% 8% 10% 36%	2199
	21st to end	Night	12% 8% 3 11% 7% 7% 6% 6% 7% 8% 25%	2414
June	1st to 10th	Night	14% 7% 4 7% 4 5% 4 4 7% 7% 37%	1330
	11th to 20th	Night	17% 7% 2 5% 4 5% 5% 5% 8% 9% 33%	1330
	21st to end	Night	6% 4 2 6% 4 5% 5% 4 7% 10% 48%	1330
July	1st to 10th	Night	4 3 2 5% 4 5% 5% 5% 7% 10% 51%	2220
	11th to 20th	Night	5% 4 2 6% 4 4 5% 4 8% 11% 49%	2220
	21st to end	Night	3 3 2 4 3 3 4 3 5% 8% 62%	2497
August	1st to 10th	Night	6% 4 2 6% 4 4 5% 4 7% 8% 50%	2610
	11th to 20th	Night	5% 4 2 7% 4 5% 6% 6% 7% 10% 45%	2811
	21st to end	Night	7% 3 1 3 3 3 4 4 5% 8% 60%	3146
September	1st to 10th	Night	10% 5% 2 5% 3 4 4 4 6% 8% 49%	1824
	11th to 20th	Night	11% 5% 1 6% 4 3 3 3 4 8% 51%	2090
	21st to end	Night	7% 5% 2 6% 4 4 5% 4 6% 7% 49%	2090
October	1st to 10th	Night	7% 5% 2 5% 4 3 4 3 5% 9% 53%	3676
	11th to 20th	Night	6% 7% 3 6% 4 4 4 3 5% 8% 49%	3900
	21st to end	Night	6% 6% 2 7% 6% 5% 5% 4 6% 7% 46%	4457
November	1st to 10th	Night	10% 12% 3 8% 5% 5% 5% 4 6% 8% 34%	2629
	11th to 20th	Night	5% 10% 4 7% 5% 4 5% 5% 7% 8% 40%	2660
	21st to end	Night	5% 11% 3 9% 4 4 5% 3 7% 10% 39%	2829
December	1st to 10th	Night	5% 12% 4 10% 6% 6% 5% 4 6% 8% 35%	2850
	11th to 20th	Night	3 9% 5% 10% 6% 6% 6% 5% 7% 9% 35%	3510
	21st to end	Night	5% 9% 3 7% 5% 5% 5% 4 5% 8% 44%	5214

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	43% 10% 17% 21% 7% 1	2219
	11th to 20th	Day	47% 7% 13% 14% 15% 3	2234
	21st to end	Day	40% 8% 15% 30% 6% 1	2794
February	1st to 10th	Day	55% 7% 13% 16% 8% 1	1583
	11th to 20th	Day	50% 9% 14% 17% 7% 2	1674
	21st to end	Day	52% 7% 11% 18% 11% 1	1494
March	1st to 10th	Day	45% 8% 15% 20% 11% 1	3169
	11th to 20th	Day	35% 7% 21% 25% 10% 1	3490
	21st to end	Day	56% 10% 13% 17% 4	3825
April	1st to 10th	Day	49% 8% 14% 21% 8%	2333
	11th to 20th	Day	48% 7% 13% 22% 9% 2	2440
	21st to end	Day	44% 8% 15% 22% 10% 1	2470
May	1st to 10th	Day	52% 7% 11% 25% 5%	4223
	11th to 20th	Day	37% 11% 16% 26% 10%	4694
	21st to end	Day	46% 10% 15% 21% 7% 1	5162
June	1st to 10th	Day	42% 8% 18% 20% 10% 2	2850
	11th to 20th	Day	45% 9% 15% 20% 9% 2	2850
	21st to end	Day	30% 8% 18% 29% 12% 3	2850
July	1st to 10th	Day	24% 7% 15% 29% 20% 5%	4666
	11th to 20th	Day	20% 6% 17% 34% 19% 4	4659
	21st to end	Day	14% 4 11% 29% 26% 16%	4892
August	1st to 10th	Day	29% 6% 13% 37% 14% 2	4304
	11th to 20th	Day	27% 7% 18% 37% 9% 2	4067
	21st to end	Day	24% 4 13% 40% 16% 2	4520
September	1st to 10th	Day	29% 5% 14% 27% 16% 8%	2353
	11th to 20th	Day	35% 7% 13% 29% 13% 3	2090
	21st to end	Day	33% 7% 13% 31% 13% 3	2090
October	1st to 10th	Day	37% 6% 11% 33% 12% 1	3298
	11th to 20th	Day	32% 6% 17% 27% 15% 2	3015
	21st to end	Day	35% 5% 12% 33% 11% 3	3101
November	1st to 10th	Day	50% 8% 13% 21% 8% 1	1589
	11th to 20th	Day	41% 8% 17% 24% 9%	1520
	21st to end	Day	41% 8% 17% 22% 10% 2	1349
December	1st to 10th	Day	49% 7% 13% 18% 9% 3	1330
	11th to 20th	Day	48% 7% 16% 24% 4 1	1684
	21st to end	Day	34% 7% 15% 22% 20% 1	2442
January	1st to 10th	Night	47% 10% 15% 21% 6% 1	4726
	11th to 20th	Night	49% 6% 13% 14% 15% 2	4740
	21st to end	Night	40% 8% 17% 25% 10% 1	4863
February	1st to 10th	Night	51% 7% 13% 16% 11% 2	2596
	11th to 20th	Night	50% 9% 13% 18% 9% 1	2403
	21st to end	Night	46% 7% 16% 19% 9% 2	1957
March	1st to 10th	Night	45% 10% 14% 22% 8% 1	3705
	11th to 20th	Night	35% 8% 21% 24% 12% 1	3490
	21st to end	Night	60% 9% 13% 13% 4 1	3828
April	1st to 10th	Night	47% 9% 14% 20% 11%	1843
	11th to 20th	Night	48% 8% 12% 21% 10% 1	1691
	21st to end	Night	45% 8% 12% 24% 9% 1	1710
May	1st to 10th	Night	54% 7% 11% 21% 6% 1	2746
	11th to 20th	Night	35% 12% 16% 28% 8% 1	2199
	21st to end	Night	48% 12% 16% 17% 5% 1	2414
June	1st to 10th	Night	43% 9% 14% 23% 10% 2	1330
	11th to 20th	Night	43% 8% 15% 22% 9% 3	1330
	21st to end	Night	30% 7% 19% 27% 16% 2	1330
July	1st to 10th	Night	24% 9% 19% 24% 21% 3	2185
	11th to 20th	Night	28% 7% 14% 31% 16% 5%	2178
	21st to end	Night	21% 5% 9% 29% 24% 13%	2418
August	1st to 10th	Night	29% 7% 14% 31% 16% 3	2602
	11th to 20th	Night	32% 7% 19% 26% 13% 2	2838
	21st to end	Night	22% 5% 14% 38% 18% 4	3146
September	1st to 10th	Night	30% 7% 13% 25% 18% 7%	1824
	11th to 20th	Night	32% 6% 13% 27% 16% 5%	2090
	21st to end	Night	31% 6% 15% 29% 15% 3	2090
October	1st to 10th	Night	29% 5% 11% 33% 19% 3	3676
	11th to 20th	Night	33% 5% 16% 26% 17% 3	3900
	21st to end	Night	36% 6% 11% 31% 16% 1	4457
November	1st to 10th	Night	47% 7% 13% 21% 10% 2	2629
	11th to 20th	Night	39% 9% 17% 20% 14% 1	2660
	21st to end	Night	40% 8% 20% 20% 10% 3	2829
December	1st to 10th	Night	47% 6% 15% 20% 10% 2	2850
	11th to 20th	Night	43% 9% 22% 21% 4 1	3507
	21st to end	Night	37% 7% 14% 24% 15% 4	5214

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	4 14% 28% 29% 13% 11%	180
	11th to 20th	Day	6% 9% 32% 31% 16% 5%	180
	21st to end	Day	9% 9% 33% 28% 17% 5%	198
February	1st to 10th	Day	15% 9% 33% 30% 9% 3	211
	11th to 20th	Day	8% 11% 30% 31% 16% 3	270
	21st to end	Day	10% 12% 27% 32% 15% 4	306
March	1st to 10th	Day	9% 14% 35% 25% 13% 5%	460
	11th to 20th	Day	8% 11% 29% 28% 19% 5%	460
	21st to end	Day	12% 10% 31% 25% 16% 5%	506
April	1st to 10th	Day	13% 14% 30% 26% 14% 2	460
	11th to 20th	Day	13% 8% 29% 29% 17% 4	452
	21st to end	Day	15% 12% 28% 27% 15% 4	460
May	1st to 10th	Day	15% 11% 21% 26% 20% 8%	524
	11th to 20th	Day	14% 6% 22% 28% 24% 6%	675
	21st to end	Day	16% 7% 19% 29% 19% 8%	734
June	1st to 10th	Day	13% 10% 24% 32% 16% 4	680
	11th to 20th	Day	16% 11% 26% 29% 16% 2	680
	21st to end	Day	8% 4 25% 32% 23% 8%	680
July	1st to 10th	Day	7% 4 17% 35% 28% 9%	671
	11th to 20th	Day	7% 5% 21% 34% 24% 9%	668
	21st to end	Day	4 4 21% 37% 25% 9%	689
August	1st to 10th	Day	8% 4 20% 34% 25% 9%	487
	11th to 20th	Day	8% 4 17% 33% 26% 12%	477
	21st to end	Day	10% 6% 21% 29% 25% 10%	539
September	1st to 10th	Day	11% 7% 24% 27% 22% 8%	490
	11th to 20th	Day	16% 8% 24% 26% 21% 6%	490
	21st to end	Day	13% 14% 26% 31% 12% 4	490
October	1st to 10th	Day	17% 9% 20% 26% 22% 6%	376
	11th to 20th	Day	11% 13% 29% 24% 18% 5%	300
	21st to end	Day	16% 17% 26% 24% 14% 2	330
November	1st to 10th	Day	21% 11% 27% 25% 12% 2	291
	11th to 20th	Day	12% 14% 36% 27% 9% 2	270
	21st to end	Day	5% 13% 37% 22% 15% 7%	189
December	1st to 10th	Day	8% 12% 32% 29% 14% 5%	180
	11th to 20th	Day	12% 17% 37% 22% 11% 2	180
	21st to end	Day	12% 7% 28% 26% 21% 6%	198
January	1st to 10th	Night	10% 14% 34% 27% 14% 1	950
	11th to 20th	Night	10% 10% 35% 32% 12% 2	950
	21st to end	Night	12% 11% 35% 29% 11% 2	837
February	1st to 10th	Night	10% 11% 29% 32% 14% 4	760
	11th to 20th	Night	10% 9% 32% 34% 13% 2	744
	21st to end	Night	10% 7% 28% 30% 21% 4	628
March	1st to 10th	Night	8% 7% 35% 33% 14% 2	760
	11th to 20th	Night	10% 10% 32% 33% 12% 2	760
	21st to end	Night	13% 10% 30% 31% 14% 3	836
April	1st to 10th	Night	13% 10% 33% 30% 13% 1	677
	11th to 20th	Night	16% 7% 31% 33% 12% 1	563
	21st to end	Night	15% 9% 29% 33% 14% 1	570
May	1st to 10th	Night	15% 9% 23% 33% 19% 1	570
	11th to 20th	Night	11% 6% 26% 32% 22% 2	374
	21st to end	Night	19% 6% 22% 31% 21% 2	411
June	1st to 10th	Night	18% 7% 28% 30% 15% 2	380
	11th to 20th	Night	18% 8% 28% 33% 12%	380
	21st to end	Night	7% 4 27% 40% 21% 1	380
July	1st to 10th	Night	6% 4 19% 46% 24% 1	370
	11th to 20th	Night	6% 4 24% 45% 19% 2	368
	21st to end	Night	4 2 25% 44% 23% 2	416
August	1st to 10th	Night	9% 4 17% 43% 25% 2	420
	11th to 20th	Night	7% 2 22% 46% 21% 2	564
	21st to end	Night	9% 4 24% 40% 22% 1	627
September	1st to 10th	Night	11% 4 25% 38% 20% 2	622
	11th to 20th	Night	16% 5% 19% 37% 22% 2	760
	21st to end	Night	9% 7% 33% 34% 14% 2	760
October	1st to 10th	Night	14% 7% 26% 34% 17% 2	760
	11th to 20th	Night	12% 8% 33% 30% 15% 2	760
	21st to end	Night	12% 10% 34% 32% 12% 1	836
November	1st to 10th	Night	17% 9% 39% 25% 9% 1	897
	11th to 20th	Night	9% 13% 41% 27% 8% 2	950
	21st to end	Night	10% 14% 35% 29% 10% 1	950
December	1st to 10th	Night	10% 11% 32% 31% 14% 2	950
	11th to 20th	Night	8% 11% 37% 31% 11% 1	950
	21st to end	Night	13% 10% 34% 29% 11% 2	1045

Page generated at 2024-11-05 06:15:48. Version ac07

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