Pelican Lake Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pelican Lake Observatory clear sky chart from 2005-11-06 to 2024-11-25.

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% 9% 3 8% 5% 5% 5% 4 6% 7% 36%	101940
	Night	12% 10% 4 9% 5% 4 4 4 5% 7% 36%	97626
Transparency	Day	45% 8% 14% 24% 9% 1	105523
	Night	45% 7% 13% 23% 11% 1	102184
Seeing	Day	15% 9% 31% 27% 14% 4	16167
	Night	15% 8% 32% 32% 11% 1	26081

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	7% 16% 7% 15% 8% 6% 4 3 5% 7% 22%	2218
	11th to 20th	Day	6% 10% 6% 16% 11% 8% 9% 7% 6% 6% 16%	2373
	21st to end	Day	6% 15% 11% 17% 7% 6% 5% 4 4 7% 18%	3114
February	1st to 10th	Day	7% 15% 5% 11% 7% 5% 5% 4 6% 7% 29%	1710
	11th to 20th	Day	8% 11% 4 8% 7% 7% 5% 5% 7% 5% 35%	1664
	21st to end	Day	10% 13% 4 11% 7% 6% 5% 3 5% 6% 31%	1413
March	1st to 10th	Day	10% 11% 4 10% 6% 5% 5% 4 5% 7% 34%	3404
	11th to 20th	Day	9% 9% 4 10% 5% 4 4 4 6% 7% 38%	3480
	21st to end	Day	21% 13% 4 9% 5% 4 4 3 4 7% 27%	3814
April	1st to 10th	Day	17% 12% 3 8% 6% 4 4 3 5% 6% 33%	2278
	11th to 20th	Day	18% 13% 4 7% 4 5% 4 3 5% 6% 32%	2352
	21st to end	Day	22% 10% 3 6% 5% 4 4 4 4 5% 33%	2470
May	1st to 10th	Day	19% 8% 2 6% 4 4 4 4 5% 7% 37%	4269
	11th to 20th	Day	15% 8% 2 6% 4 4 4 3 6% 7% 41%	4399
	21st to end	Day	17% 7% 3 7% 5% 4 5% 4 6% 8% 34%	4824
June	1st to 10th	Day	12% 5% 2 6% 5% 5% 5% 5% 6% 9% 42%	2777
	11th to 20th	Day	16% 7% 2 6% 5% 5% 5% 4 5% 7% 38%	2850
	21st to end	Day	11% 6% 2 5% 5% 6% 7% 5% 7% 10% 38%	2850
July	1st to 10th	Day	7% 4 2 7% 5% 5% 6% 5% 9% 9% 40%	4750
	11th to 20th	Day	7% 4 1 4 3 4 4 4 6% 10% 52%	4671
	21st to end	Day	6% 5% 2 5% 4 4 5% 5% 7% 10% 48%	4791
August	1st to 10th	Day	12% 5% 2 5% 4 5% 4 4 7% 8% 44%	4104
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 7% 9% 42%	4041
	21st to end	Day	14% 7% 3 6% 4 4 4 4 5% 6% 42%	4440
September	1st to 10th	Day	10% 5% 2 6% 4 4 4 4 6% 8% 46%	2280
	11th to 20th	Day	12% 6% 3 7% 5% 5% 5% 3 6% 7% 42%	2205
	21st to end	Day	15% 7% 2 6% 4 4 5% 4 5% 6% 42%	2028
October	1st to 10th	Day	18% 9% 3 6% 3 4 4 3 5% 7% 38%	1900
	11th to 20th	Day	16% 14% 4 7% 4 4 4 2 4 5% 36%	1900
	21st to end	Day	19% 12% 5% 7% 4 3 4 4 4 6% 31%	2048
November	1st to 10th	Day	13% 13% 5% 10% 6% 4 4 3 5% 6% 32%	1567
	11th to 20th	Day	13% 16% 6% 13% 7% 5% 3 3 5% 5% 25%	1600
	21st to end	Day	13% 12% 6% 10% 7% 5% 5% 4 7% 7% 24%	1552
December	1st to 10th	Day	10% 15% 5% 12% 8% 6% 6% 3 4 6% 23%	1520
	11th to 20th	Day	10% 14% 7% 13% 7% 6% 6% 4 5% 5% 24%	1842
	21st to end	Day	21% 17% 6% 14% 6% 5% 3 2 4 4 18%	2442
January	1st to 10th	Night	9% 11% 5% 14% 9% 5% 4 4 6% 6% 27%	4737
	11th to 20th	Night	6% 13% 5% 13% 10% 8% 10% 5% 5% 6% 20%	4594
	21st to end	Night	8% 18% 11% 15% 5% 4 5% 3 4 5% 21%	4550
February	1st to 10th	Night	6% 10% 5% 10% 7% 5% 5% 5% 6% 7% 34%	2470
	11th to 20th	Night	6% 10% 4 9% 6% 5% 5% 5% 6% 7% 37%	2403
	21st to end	Night	10% 12% 5% 9% 6% 6% 5% 3 5% 6% 32%	2041
March	1st to 10th	Night	8% 9% 3 7% 5% 4 4 3 5% 7% 44%	3479
	11th to 20th	Night	9% 10% 3 10% 6% 5% 5% 4 5% 6% 37%	3480
	21st to end	Night	21% 15% 5% 10% 5% 3 3 3 4 4 27%	3817
April	1st to 10th	Night	15% 11% 3 7% 5% 4 4 3 4 6% 36%	1901
	11th to 20th	Night	18% 11% 4 7% 4 4 4 2 4 6% 36%	1775
	21st to end	Night	19% 10% 3 8% 4 3 3 4 5% 6% 36%	1710
May	1st to 10th	Night	17% 9% 3 7% 3 4 3 3 5% 6% 40%	2635
	11th to 20th	Night	15% 6% 3 6% 3 3 5% 4 5% 6% 45%	2506
	21st to end	Night	17% 8% 2 6% 5% 5% 5% 4 5% 7% 36%	2743
June	1st to 10th	Night	11% 5% 2 5% 4 4 4 4 7% 9% 45%	1399
	11th to 20th	Night	10% 5% 2 5% 5% 5% 3 5% 6% 8% 45%	1330
	21st to end	Night	11% 5% 2 5% 4 3 5% 4 6% 7% 48%	1330
July	1st to 10th	Night	9% 4 1 5% 4 5% 5% 5% 9% 10% 43%	2220
	11th to 20th	Night	4 3 1 4 3 3 3 3 6% 7% 61%	2282
	21st to end	Night	4 3 1 5% 4 3 5% 5% 6% 9% 55%	2770
August	1st to 10th	Night	10% 6% 2 5% 4 4 4 3 6% 8% 49%	2836
	11th to 20th	Night	13% 6% 2 5% 3 3 4 3 6% 8% 49%	2798
	21st to end	Night	12% 7% 2 5% 3 4 4 3 6% 8% 45%	3223
September	1st to 10th	Night	9% 4 1 4 4 4 4 5% 5% 8% 52%	1900
	11th to 20th	Night	9% 5% 2 5% 4 4 4 2 6% 8% 51%	1971
	21st to end	Night	14% 5% 2 5% 5% 3 3 2 4 6% 50%	2133
October	1st to 10th	Night	15% 7% 2 6% 4 3 4 3 6% 6% 44%	2280
	11th to 20th	Night	14% 10% 4 8% 4 4 4 3 5% 6% 37%	2280
	21st to end	Night	18% 11% 4 8% 4 4 4 3 6% 5% 33%	2544
November	1st to 10th	Night	14% 11% 4 8% 6% 4 5% 3 5% 7% 34%	2731
	11th to 20th	Night	15% 13% 5% 11% 5% 5% 4 4 5% 6% 28%	2800
	21st to end	Night	12% 10% 5% 10% 7% 5% 4 4 6% 7% 30%	2723
December	1st to 10th	Night	9% 14% 6% 14% 7% 7% 5% 4 5% 6% 24%	2660
	11th to 20th	Night	11% 15% 6% 12% 7% 6% 5% 4 6% 7% 24%	3350
	21st to end	Night	22% 19% 5% 12% 5% 4 3 3 4 5% 19%	5225

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	61% 7% 10% 17% 5%	2219
	11th to 20th	Day	63% 9% 9% 15% 4	2373
	21st to end	Day	64% 8% 9% 14% 5%	3114
February	1st to 10th	Day	53% 5% 10% 22% 9% 1	1710
	11th to 20th	Day	48% 7% 14% 21% 9% 1	1673
	21st to end	Day	53% 6% 12% 16% 12% 1	1413
March	1st to 10th	Day	47% 9% 13% 21% 9%	3404
	11th to 20th	Day	42% 7% 14% 28% 9%	3480
	21st to end	Day	57% 7% 11% 20% 4	3814
April	1st to 10th	Day	51% 6% 11% 19% 12% 2	2278
	11th to 20th	Day	52% 7% 12% 18% 11% 1	2352
	21st to end	Day	52% 7% 10% 20% 10%	2470
May	1st to 10th	Day	43% 8% 15% 21% 12% 2	4307
	11th to 20th	Day	39% 8% 15% 25% 10% 3	4403
	21st to end	Day	43% 11% 15% 23% 8% 1	4837
June	1st to 10th	Day	36% 9% 18% 27% 10% 1	2777
	11th to 20th	Day	43% 8% 14% 22% 13% 1	2850
	21st to end	Day	37% 10% 18% 26% 8% 1	2850
July	1st to 10th	Day	36% 11% 18% 22% 12% 1	4676
	11th to 20th	Day	24% 8% 18% 36% 12% 1	4590
	21st to end	Day	29% 9% 18% 32% 12% 1	4640
August	1st to 10th	Day	35% 7% 16% 29% 12% 1	4090
	11th to 20th	Day	36% 8% 17% 31% 8%	4080
	21st to end	Day	40% 8% 14% 26% 10% 1	4439
September	1st to 10th	Day	34% 8% 15% 33% 10%	2280
	11th to 20th	Day	38% 9% 19% 26% 8%	2205
	21st to end	Day	41% 7% 13% 31% 8% 1	2028
October	1st to 10th	Day	35% 5% 14% 31% 15% 1	3160
	11th to 20th	Day	43% 5% 10% 23% 17% 1	3140
	21st to end	Day	52% 5% 13% 24% 6%	3351
November	1st to 10th	Day	53% 7% 11% 18% 10% 1	1567
	11th to 20th	Day	61% 5% 13% 14% 7% 1	1600
	21st to end	Day	54% 9% 14% 16% 5% 2	1552
December	1st to 10th	Day	61% 7% 13% 14% 5%	1520
	11th to 20th	Day	60% 8% 11% 17% 4	1839
	21st to end	Day	70% 6% 6% 12% 5%	2442
January	1st to 10th	Night	55% 7% 12% 20% 5%	4737
	11th to 20th	Night	61% 9% 13% 12% 5% 1	4594
	21st to end	Night	64% 6% 9% 17% 5%	4550
February	1st to 10th	Night	48% 6% 12% 23% 11% 1	2470
	11th to 20th	Night	44% 8% 13% 24% 11% 1	2404
	21st to end	Night	51% 8% 10% 20% 10% 1	2041
March	1st to 10th	Night	38% 7% 16% 22% 14% 2	3479
	11th to 20th	Night	43% 8% 12% 23% 13%	3480
	21st to end	Night	61% 5% 9% 17% 7% 1	3817
April	1st to 10th	Night	48% 6% 10% 19% 15% 1	1901
	11th to 20th	Night	49% 6% 7% 20% 16% 1	1775
	21st to end	Night	48% 6% 11% 21% 13% 2	1710
May	1st to 10th	Night	42% 8% 12% 25% 11% 2	2662
	11th to 20th	Night	36% 8% 12% 24% 17% 3	2507
	21st to end	Night	44% 9% 13% 21% 12% 1	2751
June	1st to 10th	Night	32% 10% 21% 26% 10% 2	1399
	11th to 20th	Night	34% 9% 16% 23% 16% 1	1330
	21st to end	Night	34% 8% 16% 29% 12% 2	1330
July	1st to 10th	Night	32% 11% 19% 24% 13% 1	2185
	11th to 20th	Night	20% 8% 14% 41% 15% 3	2240
	21st to end	Night	23% 8% 19% 34% 14% 2	2682
August	1st to 10th	Night	33% 7% 16% 27% 15% 3	2826
	11th to 20th	Night	32% 7% 15% 34% 11% 1	2825
	21st to end	Night	36% 8% 18% 27% 11% 1	3223
September	1st to 10th	Night	29% 7% 17% 34% 12% 1	1900
	11th to 20th	Night	31% 7% 18% 32% 12%	1971
	21st to end	Night	35% 6% 12% 35% 12%	2133
October	1st to 10th	Night	28% 4 8% 36% 19% 4	3800
	11th to 20th	Night	40% 5% 11% 24% 19% 1	3779
	21st to end	Night	47% 6% 14% 22% 10%	4192
November	1st to 10th	Night	49% 6% 12% 23% 9% 1	2731
	11th to 20th	Night	55% 7% 13% 16% 8% 1	2800
	21st to end	Night	51% 8% 16% 18% 5% 1	2723
December	1st to 10th	Night	59% 7% 13% 15% 4 1	2660
	11th to 20th	Night	58% 7% 12% 15% 6% 1	3352
	21st to end	Night	68% 5% 8% 13% 5%	5225

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	11% 9% 36% 32% 9% 3	270
	11th to 20th	Day	16% 8% 33% 34% 9%	270
	21st to end	Day	12% 7% 38% 25% 14% 3	297
February	1st to 10th	Day	16% 14% 40% 22% 7%	270
	11th to 20th	Day	17% 15% 36% 23% 7% 2	270
	21st to end	Day	12% 12% 39% 33% 3	225
March	1st to 10th	Day	15% 13% 40% 24% 6% 1	270
	11th to 20th	Day	17% 6% 38% 25% 12% 3	270
	21st to end	Day	23% 14% 29% 19% 12% 3	297
April	1st to 10th	Day	23% 13% 32% 24% 7% 1	458
	11th to 20th	Day	25% 12% 27% 24% 11% 1	550
	21st to end	Day	24% 11% 28% 24% 12% 1	650
May	1st to 10th	Day	20% 14% 30% 23% 10% 2	653
	11th to 20th	Day	19% 10% 30% 27% 11% 3	675
	21st to end	Day	17% 10% 27% 31% 13% 3	734
June	1st to 10th	Day	11% 7% 31% 30% 17% 3	680
	11th to 20th	Day	17% 9% 34% 27% 11% 2	680
	21st to end	Day	12% 8% 32% 27% 17% 4	680
July	1st to 10th	Day	7% 5% 24% 28% 28% 9%	671
	11th to 20th	Day	9% 6% 30% 26% 20% 9%	668
	21st to end	Day	6% 4 26% 32% 23% 8%	739
August	1st to 10th	Day	11% 5% 23% 30% 25% 6%	676
	11th to 20th	Day	11% 6% 22% 31% 24% 6%	665
	21st to end	Day	11% 9% 24% 32% 19% 5%	695
September	1st to 10th	Day	10% 6% 29% 32% 18% 4	490
	11th to 20th	Day	11% 7% 29% 31% 17% 6%	415
	21st to end	Day	18% 12% 33% 21% 12% 4	300
October	1st to 10th	Day	21% 11% 29% 24% 9% 6%	300
	11th to 20th	Day	16% 14% 39% 25% 6% 1	300
	21st to end	Day	25% 14% 38% 15% 6% 1	330
November	1st to 10th	Day	17% 14% 35% 25% 8% 1	300
	11th to 20th	Day	21% 14% 43% 18% 4	300
	21st to end	Day	21% 11% 41% 22% 5%	282
December	1st to 10th	Day	15% 9% 41% 26% 9% 1	270
	11th to 20th	Day	17% 17% 35% 27% 4	270
	21st to end	Day	24% 10% 34% 24% 6% 1	297
January	1st to 10th	Night	12% 11% 36% 31% 9% 2	950
	11th to 20th	Night	16% 8% 36% 30% 8% 1	950
	21st to end	Night	17% 10% 36% 28% 8% 1	1045
February	1st to 10th	Night	11% 9% 39% 31% 10% 1	950
	11th to 20th	Night	10% 10% 43% 26% 10% 1	929
	21st to end	Night	16% 8% 36% 29% 10% 1	785
March	1st to 10th	Night	14% 11% 36% 29% 8% 1	608
	11th to 20th	Night	15% 9% 42% 27% 6% 1	570
	21st to end	Night	21% 10% 26% 30% 10% 2	627
April	1st to 10th	Night	19% 8% 37% 29% 6%	570
	11th to 20th	Night	23% 8% 31% 29% 9% 1	563
	21st to end	Night	23% 6% 31% 30% 9% 1	570
May	1st to 10th	Night	18% 10% 34% 29% 8% 1	570
	11th to 20th	Night	16% 8% 31% 36% 8% 1	561
	21st to end	Night	14% 8% 27% 38% 13%	617
June	1st to 10th	Night	12% 5% 29% 38% 14% 1	570
	11th to 20th	Night	12% 4 34% 42% 9%	570
	21st to end	Night	13% 6% 24% 40% 17% 1	570
July	1st to 10th	Night	5% 2 23% 42% 25% 2	555
	11th to 20th	Night	7% 3 28% 41% 20% 1	552
	21st to end	Night	5% 3 23% 44% 23% 2	624
August	1st to 10th	Night	8% 3 17% 49% 21% 2	567
	11th to 20th	Night	11% 4 20% 38% 25% 2	564
	21st to end	Night	12% 5% 24% 37% 20% 2	627
September	1st to 10th	Night	10% 5% 24% 40% 19% 2	570
	11th to 20th	Night	11% 6% 30% 32% 20% 1	570
	21st to end	Night	15% 7% 34% 28% 14% 2	613
October	1st to 10th	Night	18% 10% 31% 30% 11% 1	760
	11th to 20th	Night	20% 11% 35% 29% 6% 1	760
	21st to end	Night	22% 12% 33% 28% 6%	851
November	1st to 10th	Night	18% 9% 33% 30% 9%	975
	11th to 20th	Night	19% 12% 35% 24% 8% 1	1000
	21st to end	Night	17% 13% 39% 25% 6%	973
December	1st to 10th	Night	15% 11% 33% 31% 8% 1	950
	11th to 20th	Night	20% 10% 37% 26% 7% 1	950
	21st to end	Night	25% 11% 33% 25% 5% 1	1045

Page generated at 2024-11-22 07:02:28. Version ac07

Copyright © 2024 Attilla Danko.