Chain Lake Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chain Lake Provincial Park clear sky chart from 2005-11-06 to 2024-11-05.

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	7% 8% 3 7% 5% 5% 5% 4 6% 8% 41%	105558
	Night	5% 8% 3 8% 5% 5% 5% 4 6% 8% 44%	102082
Transparency	Day	38% 9% 15% 23% 12% 3	105307
	Night	36% 9% 16% 23% 13% 3	101979
Seeing	Day	15% 18% 31% 23% 10% 2	15326
	Night	11% 17% 32% 27% 11% 2	24389

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	1 6% 5% 10% 7% 6% 5% 4 7% 9% 39%	2219
	11th to 20th	Day	2 7% 4 9% 6% 6% 5% 5% 8% 10% 38%	2330
	21st to end	Day	1 7% 3 9% 5% 4 5% 4 8% 9% 44%	2794
February	1st to 10th	Day	3 7% 3 10% 7% 5% 6% 5% 8% 9% 36%	1524
	11th to 20th	Day	2 10% 4 9% 7% 5% 7% 5% 6% 10% 34%	1665
	21st to end	Day	2 10% 5% 11% 6% 5% 6% 4 7% 8% 35%	1555
March	1st to 10th	Day	1 6% 4 10% 6% 5% 6% 5% 8% 10% 38%	3138
	11th to 20th	Day	3 11% 3 6% 4 3 4 4 5% 8% 49%	3448
	21st to end	Day	5% 17% 7% 15% 5% 5% 4 3 5% 6% 27%	3884
April	1st to 10th	Day	7% 14% 4 10% 5% 6% 4 5% 7% 8% 31%	2313
	11th to 20th	Day	7% 16% 5% 9% 5% 5% 5% 4 6% 8% 30%	2440
	21st to end	Day	9% 14% 4 8% 6% 4 5% 5% 6% 7% 33%	2470
May	1st to 10th	Day	15% 18% 4 7% 4 4 4 3 5% 7% 27%	4223
	11th to 20th	Day	9% 9% 3 9% 6% 6% 6% 5% 7% 8% 32%	4687
	21st to end	Day	15% 10% 3 9% 6% 5% 6% 5% 7% 7% 27%	5161
June	1st to 10th	Day	16% 9% 3 7% 6% 5% 5% 5% 6% 7% 30%	2850
	11th to 20th	Day	21% 8% 3 8% 6% 6% 5% 4 6% 6% 27%	2850
	21st to end	Day	9% 5% 2 5% 6% 5% 6% 6% 7% 8% 41%	2850
July	1st to 10th	Day	6% 5% 2 5% 4 4 5% 4 6% 9% 50%	4740
	11th to 20th	Day	5% 3 1 4 3 4 6% 5% 8% 9% 51%	4740
	21st to end	Day	3 2 1 4 3 4 4 4 5% 8% 61%	4922
August	1st to 10th	Day	10% 5% 2 4 4 4 6% 6% 8% 9% 42%	4401
	11th to 20th	Day	8% 4 2 5% 4 4 6% 5% 6% 9% 48%	4040
	21st to end	Day	8% 3 2 4 3 4 4 4 6% 7% 55%	4521
September	1st to 10th	Day	11% 6% 2 5% 4 3 4 3 4 7% 51%	2333
	11th to 20th	Day	12% 6% 2 5% 5% 4 4 4 4 7% 47%	2090
	21st to end	Day	9% 8% 2 4 3 3 5% 4 5% 8% 49%	2090
October	1st to 10th	Day	6% 6% 2 6% 4 4 5% 4 6% 11% 47%	3372
	11th to 20th	Day	3 7% 2 6% 4 4 4 4 8% 12% 47%	2916
	21st to end	Day	4 8% 3 7% 5% 4 5% 4 6% 8% 47%	3101
November	1st to 10th	Day	5% 13% 4 8% 5% 5% 4 5% 6% 7% 39%	1630
	11th to 20th	Day	3 8% 4 8% 4 4 4 4 6% 9% 47%	1477
	21st to end	Day	3 12% 3 10% 5% 5% 4 4 5% 8% 41%	1330
December	1st to 10th	Day	2 7% 3 10% 7% 4 6% 5% 5% 9% 42%	1330
	11th to 20th	Day	3 9% 4 10% 6% 5% 5% 4 9% 9% 36%	1682
	21st to end	Day	2 8% 3 7% 5% 5% 4 4 6% 9% 47%	2442
January	1st to 10th	Night	1 8% 4 10% 7% 7% 6% 5% 7% 10% 34%	4726
	11th to 20th	Night	2 7% 3 10% 8% 6% 5% 6% 8% 8% 36%	4596
	21st to end	Night	1 10% 4 9% 6% 5% 5% 4 7% 8% 40%	4862
February	1st to 10th	Night	2 8% 4 11% 6% 5% 5% 5% 7% 9% 39%	2656
	11th to 20th	Night	1 10% 5% 11% 7% 5% 5% 4 6% 8% 36%	2402
	21st to end	Night	2 8% 4 11% 7% 7% 6% 3 6% 6% 40%	1899
March	1st to 10th	Night	1 6% 3 12% 9% 8% 7% 4 7% 7% 36%	3736
	11th to 20th	Night	3 8% 3 6% 3 4 4 3 5% 8% 52%	3531
	21st to end	Night	6% 17% 7% 13% 5% 4 4 4 5% 7% 28%	3767
April	1st to 10th	Night	6% 13% 4 9% 5% 4 3 4 5% 7% 40%	1866
	11th to 20th	Night	8% 13% 4 9% 4 4 5% 4 6% 7% 34%	1691
	21st to end	Night	7% 12% 5% 10% 5% 4 5% 4 5% 7% 36%	1710
May	1st to 10th	Night	13% 16% 4 8% 4 3 3 4 5% 7% 32%	2742
	11th to 20th	Night	9% 7% 2 7% 5% 6% 5% 4 6% 9% 39%	2204
	21st to end	Night	15% 8% 3 8% 5% 5% 5% 4 7% 8% 32%	2414
June	1st to 10th	Night	14% 7% 3 6% 5% 5% 4 4 6% 5% 41%	1330
	11th to 20th	Night	19% 8% 2 6% 5% 5% 4 3 5% 8% 35%	1330
	21st to end	Night	7% 4 2 4 3 4 6% 5% 6% 8% 51%	1330
July	1st to 10th	Night	4 4 1 4 4 4 5% 5% 7% 9% 54%	2220
	11th to 20th	Night	5% 4 2 4 4 3 4 3 7% 8% 57%	2220
	21st to end	Night	4 3 1 3 3 3 3 2 4 6% 67%	2626
August	1st to 10th	Night	10% 6% 2 5% 4 3 4 4 5% 8% 49%	2529
	11th to 20th	Night	6% 4 2 5% 4 5% 6% 4 7% 9% 48%	2798
	21st to end	Night	6% 3 1 5% 3 4 4 3 5% 8% 57%	3146
September	1st to 10th	Night	11% 4 1 4 3 3 4 3 5% 7% 55%	1844
	11th to 20th	Night	11% 8% 2 3 2 3 3 3 6% 8% 52%	2090
	21st to end	Night	9% 7% 2 4 3 3 3 3 6% 8% 52%	2090
October	1st to 10th	Night	5% 6% 2 4 3 3 4 4 5% 7% 57%	3604
	11th to 20th	Night	3 6% 2 4 3 3 4 5% 8% 10% 52%	4010
	21st to end	Night	3 8% 3 6% 4 4 4 4 6% 7% 51%	4457
November	1st to 10th	Night	5% 12% 5% 8% 5% 4 4 4 7% 7% 39%	2530
	11th to 20th	Night	2 8% 2 6% 5% 4 5% 4 7% 9% 47%	2702
	21st to end	Night	2 9% 3 9% 5% 6% 4 3 7% 10% 42%	2850
December	1st to 10th	Night	2 9% 4 8% 6% 5% 5% 5% 6% 9% 42%	2850
	11th to 20th	Night	2 7% 4 11% 6% 5% 6% 5% 8% 10% 36%	3510
	21st to end	Night	2 9% 4 9% 5% 4 5% 4 6% 6% 46%	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	39% 9% 15% 24% 11% 3	2219
	11th to 20th	Day	41% 8% 13% 16% 16% 6%	2352
	21st to end	Day	31% 14% 17% 28% 8% 1	2794
February	1st to 10th	Day	42% 13% 15% 19% 9% 2	1524
	11th to 20th	Day	43% 10% 16% 19% 9% 3	1674
	21st to end	Day	46% 8% 15% 17% 12% 2	1555
March	1st to 10th	Day	34% 12% 18% 19% 17% 1	3138
	11th to 20th	Day	32% 7% 21% 27% 13% 1	3449
	21st to end	Day	55% 10% 13% 17% 5%	3884
April	1st to 10th	Day	50% 9% 16% 17% 7% 1	2313
	11th to 20th	Day	51% 8% 14% 17% 9% 1	2440
	21st to end	Day	48% 9% 16% 18% 8% 1	2470
May	1st to 10th	Day	58% 7% 11% 20% 4	4223
	11th to 20th	Day	43% 12% 16% 21% 8%	4691
	21st to end	Day	48% 12% 19% 11% 9% 1	5162
June	1st to 10th	Day	49% 10% 15% 16% 10% 1	2850
	11th to 20th	Day	54% 9% 11% 14% 10% 2	2850
	21st to end	Day	35% 11% 16% 23% 12% 2	2850
July	1st to 10th	Day	29% 8% 13% 27% 18% 6%	4666
	11th to 20th	Day	25% 8% 14% 31% 18% 4	4659
	21st to end	Day	21% 5% 9% 25% 24% 16%	4766
August	1st to 10th	Day	32% 10% 16% 27% 12% 2	4384
	11th to 20th	Day	29% 9% 21% 30% 9% 2	4079
	21st to end	Day	26% 6% 13% 38% 15% 2	4520
September	1st to 10th	Day	34% 6% 12% 24% 18% 6%	2333
	11th to 20th	Day	35% 8% 14% 26% 15% 2	2090
	21st to end	Day	33% 8% 14% 29% 13% 3	2090
October	1st to 10th	Day	32% 7% 16% 35% 10% 1	3372
	11th to 20th	Day	30% 6% 22% 25% 15% 3	2916
	21st to end	Day	35% 7% 14% 26% 14% 4	3101
November	1st to 10th	Day	44% 9% 14% 19% 13%	1630
	11th to 20th	Day	34% 10% 20% 22% 12% 1	1477
	21st to end	Day	40% 8% 20% 19% 9% 4	1330
December	1st to 10th	Day	39% 9% 18% 19% 11% 4	1330
	11th to 20th	Day	41% 11% 19% 21% 7% 1	1684
	21st to end	Day	31% 9% 13% 23% 17% 6%	2442
January	1st to 10th	Night	39% 13% 15% 21% 9% 2	4726
	11th to 20th	Night	42% 9% 14% 15% 14% 6%	4636
	21st to end	Night	35% 12% 18% 22% 11% 1	4862
February	1st to 10th	Night	42% 10% 14% 18% 13% 3	2656
	11th to 20th	Night	43% 9% 17% 18% 11% 2	2403
	21st to end	Night	46% 7% 12% 21% 11% 3	1899
March	1st to 10th	Night	41% 10% 16% 20% 13%	3736
	11th to 20th	Night	28% 10% 23% 24% 15%	3531
	21st to end	Night	54% 10% 13% 17% 5% 1	3767
April	1st to 10th	Night	43% 8% 15% 21% 11% 1	1866
	11th to 20th	Night	47% 8% 13% 22% 8% 1	1691
	21st to end	Night	47% 9% 13% 22% 8% 2	1710
May	1st to 10th	Night	51% 8% 12% 24% 5%	2742
	11th to 20th	Night	34% 10% 16% 29% 9% 1	2204
	21st to end	Night	45% 11% 16% 17% 9% 1	2414
June	1st to 10th	Night	44% 8% 15% 22% 10% 1	1330
	11th to 20th	Night	47% 8% 15% 20% 10% 1	1330
	21st to end	Night	28% 10% 19% 27% 14% 2	1330
July	1st to 10th	Night	24% 7% 19% 23% 21% 6%	2185
	11th to 20th	Night	24% 8% 16% 30% 17% 5%	2178
	21st to end	Night	19% 4 9% 31% 24% 14%	2543
August	1st to 10th	Night	33% 7% 17% 24% 17% 3	2521
	11th to 20th	Night	30% 8% 20% 30% 11% 2	2825
	21st to end	Night	24% 5% 16% 34% 18% 2	3146
September	1st to 10th	Night	29% 6% 15% 28% 16% 6%	1844
	11th to 20th	Night	30% 7% 16% 28% 15% 4	2090
	21st to end	Night	30% 8% 18% 27% 14% 4	2090
October	1st to 10th	Night	26% 6% 12% 30% 24% 2	3604
	11th to 20th	Night	26% 7% 20% 26% 19% 3	4010
	21st to end	Night	32% 6% 15% 31% 16% 1	4457
November	1st to 10th	Night	42% 10% 16% 20% 11% 2	2530
	11th to 20th	Night	31% 11% 19% 21% 16% 1	2702
	21st to end	Night	36% 9% 20% 20% 11% 4	2850
December	1st to 10th	Night	38% 9% 18% 19% 12% 4	2850
	11th to 20th	Night	38% 14% 21% 20% 7% 1	3507
	21st to end	Night	34% 8% 15% 23% 13% 7%	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	7% 24% 31% 21% 11% 6%	180
	11th to 20th	Day	8% 17% 41% 25% 7% 2	180
	21st to end	Day	8% 30% 38% 15% 6% 4	198
February	1st to 10th	Day	15% 24% 34% 20% 5% 2	182
	11th to 20th	Day	11% 21% 37% 22% 8% 1	270
	21st to end	Day	14% 22% 35% 24% 5% 1	367
March	1st to 10th	Day	11% 26% 37% 16% 7% 2	460
	11th to 20th	Day	12% 24% 31% 23% 8% 2	460
	21st to end	Day	14% 26% 34% 17% 7% 2	506
April	1st to 10th	Day	15% 26% 35% 19% 4	460
	11th to 20th	Day	18% 23% 31% 18% 9% 1	452
	21st to end	Day	19% 25% 27% 18% 8% 2	460
May	1st to 10th	Day	20% 16% 30% 21% 11% 2	463
	11th to 20th	Day	20% 14% 23% 25% 15% 3	668
	21st to end	Day	22% 12% 22% 28% 14% 2	734
June	1st to 10th	Day	19% 19% 29% 22% 9% 3	680
	11th to 20th	Day	22% 18% 29% 20% 9% 2	680
	21st to end	Day	11% 13% 30% 26% 15% 4	680
July	1st to 10th	Day	11% 10% 29% 28% 19% 3	671
	11th to 20th	Day	11% 12% 30% 28% 15% 3	668
	21st to end	Day	7% 14% 33% 30% 14% 2	611
August	1st to 10th	Day	11% 13% 32% 29% 13% 2	487
	11th to 20th	Day	6% 13% 31% 30% 16% 3	477
	21st to end	Day	12% 15% 33% 24% 12% 4	539
September	1st to 10th	Day	15% 18% 30% 24% 9% 4	490
	11th to 20th	Day	15% 16% 32% 23% 11% 2	490
	21st to end	Day	18% 25% 30% 19% 6% 2	490
October	1st to 10th	Day	16% 18% 30% 25% 10% 2	424
	11th to 20th	Day	15% 22% 30% 19% 11% 3	300
	21st to end	Day	17% 22% 35% 19% 4 3	330
November	1st to 10th	Day	19% 23% 33% 20% 5%	282
	11th to 20th	Day	21% 24% 37% 14% 4	249
	21st to end	Day	17% 24% 27% 19% 6% 7%	180
December	1st to 10th	Day	11% 21% 38% 21% 8% 2	180
	11th to 20th	Day	9% 24% 38% 21% 6% 2	180
	21st to end	Day	11% 16% 36% 24% 9% 5%	198
January	1st to 10th	Night	10% 24% 39% 20% 6% 1	950
	11th to 20th	Night	8% 21% 43% 20% 6% 1	885
	21st to end	Night	8% 23% 39% 23% 6% 1	836
February	1st to 10th	Night	9% 21% 34% 24% 9% 3	760
	11th to 20th	Night	7% 18% 39% 28% 8% 1	744
	21st to end	Night	8% 14% 37% 27% 12% 2	628
March	1st to 10th	Night	7% 20% 38% 24% 9% 2	760
	11th to 20th	Night	9% 22% 31% 28% 8% 1	760
	21st to end	Night	9% 16% 32% 31% 10% 3	836
April	1st to 10th	Night	12% 19% 32% 25% 10% 2	726
	11th to 20th	Night	15% 16% 31% 27% 10% 1	563
	21st to end	Night	12% 17% 33% 28% 10%	570
May	1st to 10th	Night	16% 13% 26% 30% 15% 1	504
	11th to 20th	Night	14% 9% 21% 34% 20% 2	374
	21st to end	Night	25% 6% 19% 30% 19% 1	411
June	1st to 10th	Night	17% 11% 28% 28% 14% 2	380
	11th to 20th	Night	22% 11% 28% 25% 13% 1	380
	21st to end	Night	9% 8% 24% 35% 22% 1	380
July	1st to 10th	Night	8% 6% 17% 45% 24%	370
	11th to 20th	Night	8% 7% 24% 40% 19% 2	368
	21st to end	Night	7% 7% 18% 46% 21% 1	416
August	1st to 10th	Night	10% 4 16% 40% 28% 2	378
	11th to 20th	Night	8% 4 23% 40% 24% 2	551
	21st to end	Night	8% 11% 26% 38% 15% 2	627
September	1st to 10th	Night	13% 9% 22% 34% 18% 4	690
	11th to 20th	Night	15% 7% 24% 32% 18% 4	760
	21st to end	Night	13% 17% 31% 24% 12% 4	760
October	1st to 10th	Night	14% 13% 27% 31% 13% 2	760
	11th to 20th	Night	11% 16% 31% 29% 10% 2	760
	21st to end	Night	12% 20% 34% 26% 7% 1	836
November	1st to 10th	Night	15% 24% 35% 19% 7%	821
	11th to 20th	Night	11% 28% 40% 17% 3 1	950
	21st to end	Night	8% 26% 38% 20% 6% 2	950
December	1st to 10th	Night	8% 24% 37% 22% 8% 2	950
	11th to 20th	Night	7% 25% 38% 24% 5% 1	950
	21st to end	Night	9% 21% 39% 21% 9% 1	1045

Page generated at 2024-11-03 00:11:28. Version ac07

Copyright © 2024 Attilla Danko.