MAS LaGrange site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the MAS LaGrange site clear sky chart from 2005-11-06 to 2024-11-30.

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	12% 7% 2 6% 4 4 4 4 6% 7% 43%	101013
	Night	13% 7% 2 5% 4 4 4 3 5% 7% 47%	98585
Transparency	Day	21% 47% 6% 13% 11% 3	104742
	Night	19% 47% 6% 13% 12% 4	102996
Seeing	Day	16% 11% 23% 25% 18% 7%	15363
	Night	16% 10% 25% 29% 18% 3	25136

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	14% 14% 4 7% 4 3 3 2 3 4 42%	2559
	11th to 20th	Day	19% 10% 2 7% 4 4 3 3 3 3 42%	2850
	21st to end	Day	22% 11% 2 5% 3 3 3 3 4 5% 40%	3146
February	1st to 10th	Day	20% 11% 3 5% 5% 3 3 2 3 5% 38%	1900
	11th to 20th	Day	20% 10% 3 5% 4 3 4 3 4 4 39%	1848
	21st to end	Day	23% 10% 2 7% 3 3 4 3 4 6% 36%	1570
March	1st to 10th	Day	19% 12% 4 9% 5% 4 3 3 4 4 33%	3120
	11th to 20th	Day	14% 7% 3 7% 4 3 4 3 4 6% 44%	3411
	21st to end	Day	13% 7% 3 7% 6% 5% 4 4 5% 6% 41%	4101
April	1st to 10th	Day	13% 7% 2 6% 4 5% 4 4 5% 7% 44%	2280
	11th to 20th	Day	16% 8% 2 5% 4 3 4 2 5% 5% 44%	2254
	21st to end	Day	12% 7% 3 6% 5% 5% 4 4 5% 7% 43%	2280
May	1st to 10th	Day	13% 7% 2 7% 4 4 5% 4 6% 8% 39%	3765
	11th to 20th	Day	14% 6% 3 7% 4 4 4 4 6% 9% 39%	4081
	21st to end	Day	11% 6% 2 7% 5% 5% 5% 5% 7% 9% 36%	4569
June	1st to 10th	Day	9% 6% 2 6% 6% 5% 6% 5% 6% 9% 41%	2660
	11th to 20th	Day	4 4 1 5% 5% 5% 6% 5% 7% 10% 47%	2660
	21st to end	Day	5% 4 2 5% 6% 5% 6% 5% 8% 9% 45%	2660
July	1st to 10th	Day	6% 5% 2 7% 6% 5% 6% 5% 9% 11% 38%	4440
	11th to 20th	Day	8% 5% 2 7% 6% 6% 6% 5% 8% 12% 36%	4380
	21st to end	Day	15% 8% 3 8% 6% 6% 6% 5% 6% 7% 30%	4385
August	1st to 10th	Day	3 3 1 4 4 4 4 4 6% 9% 57%	3785
	11th to 20th	Day	7% 4 2 5% 4 5% 5% 4 7% 10% 47%	3729
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 8% 53%	4180
September	1st to 10th	Day	9% 5% 2 7% 5% 5% 5% 5% 7% 7% 44%	2280
	11th to 20th	Day	12% 5% 2 7% 4 5% 4 3 6% 8% 44%	2188
	21st to end	Day	11% 6% 2 6% 4 4 3 3 4 7% 51%	2090
October	1st to 10th	Day	8% 4 2 5% 3 3 4 3 4 6% 59%	2034
	11th to 20th	Day	10% 4 2 5% 3 2 3 3 4 7% 57%	1900
	21st to end	Day	18% 6% 1 4 3 3 3 3 3 3 52%	2090
November	1st to 10th	Day	12% 5% 2 4 3 2 3 3 4 5% 56%	1762
	11th to 20th	Day	14% 6% 2 4 3 3 3 3 5% 7% 52%	1800
	21st to end	Day	18% 8% 2 4 4 3 3 3 5% 6% 44%	1797
December	1st to 10th	Day	20% 10% 3 7% 3 3 4 3 5% 6% 37%	1710
	11th to 20th	Day	14% 9% 3 7% 4 4 3 3 4 5% 44%	1966
	21st to end	Day	12% 13% 4 8% 5% 4 4 4 5% 6% 35%	2783
January	1st to 10th	Night	19% 11% 3 6% 3 3 3 3 4 4 42%	4392
	11th to 20th	Night	17% 9% 3 7% 4 3 3 3 4 4 43%	4120
	21st to end	Night	24% 9% 2 4 3 2 2 2 4 5% 43%	4518
February	1st to 10th	Night	20% 9% 3 8% 4 3 3 2 4 5% 40%	2280
	11th to 20th	Night	19% 9% 3 6% 5% 4 3 3 3 4 42%	2218
	21st to end	Night	19% 9% 2 6% 4 4 4 3 4 5% 39%	1884
March	1st to 10th	Night	20% 10% 3 6% 4 4 3 3 4 5% 39%	3733
	11th to 20th	Night	15% 6% 2 5% 3 3 4 3 4 7% 48%	3577
	21st to end	Night	14% 7% 2 7% 4 4 4 4 6% 6% 41%	3516
April	1st to 10th	Night	13% 5% 2 6% 3 3 3 3 6% 7% 47%	1900
	11th to 20th	Night	16% 6% 2 4 3 3 3 3 5% 7% 48%	1875
	21st to end	Night	11% 7% 2 5% 5% 4 4 4 4 7% 48%	1900
May	1st to 10th	Night	19% 8% 3 6% 3 3 3 3 4 7% 40%	3115
	11th to 20th	Night	13% 9% 2 5% 4 4 4 2 6% 7% 45%	2812
	21st to end	Night	9% 6% 2 7% 5% 4 4 5% 7% 10% 41%	2971
June	1st to 10th	Night	7% 6% 3 7% 3 4 6% 4 6% 11% 44%	1520
	11th to 20th	Night	3 3 1 3 3 3 4 4 6% 9% 59%	1520
	21st to end	Night	3 4 1 3 3 4 4 4 7% 10% 56%	1520
July	1st to 10th	Night	6% 4 2 6% 4 5% 5% 5% 8% 12% 44%	2530
	11th to 20th	Night	6% 4 1 4 4 3 3 4 6% 14% 50%	2585
	21st to end	Night	10% 8% 3 9% 4 5% 5% 4 7% 7% 38%	3175
August	1st to 10th	Night	2 2 1 3 2 3 4 3 6% 7% 68%	3144
	11th to 20th	Night	4 2 1 4 4 4 4 5% 7% 11% 54%	3100
	21st to end	Night	4 3 1 4 3 4 4 4 6% 10% 57%	3476
September	1st to 10th	Night	6% 5% 2 6% 4 4 5% 4 6% 6% 51%	1900
	11th to 20th	Night	9% 6% 3 5% 3 4 4 3 5% 8% 50%	1971
	21st to end	Night	10% 5% 2 4 3 3 3 3 4 6% 58%	2090
October	1st to 10th	Night	7% 4 2 4 2 3 3 2 4 7% 62%	2142
	11th to 20th	Night	11% 4 2 5% 2 3 3 3 3 6% 58%	2280
	21st to end	Night	16% 6% 2 6% 3 2 3 2 3 5% 52%	2508
November	1st to 10th	Night	11% 4 1 4 4 3 4 3 5% 5% 55%	2534
	11th to 20th	Night	11% 5% 2 4 3 3 4 3 6% 6% 52%	2600
	21st to end	Night	15% 7% 1 5% 3 3 4 3 4 5% 50%	2599
December	1st to 10th	Night	20% 8% 2 5% 3 3 3 3 4 6% 42%	2470
	11th to 20th	Night	16% 7% 3 5% 4 3 3 3 5% 5% 47%	3226
	21st to end	Night	14% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	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	32% 37% 2 12% 15% 1	2560
	11th to 20th	Day	29% 39% 4 12% 15% 1	2850
	21st to end	Day	31% 40% 4 12% 11% 2	3146
February	1st to 10th	Day	19% 64% 2 8% 5% 1	1900
	11th to 20th	Day	18% 64% 2 9% 5% 1	1858
	21st to end	Day	18% 65% 3 5% 6% 3	1570
March	1st to 10th	Day	37% 42% 3 5% 6% 7%	3120
	11th to 20th	Day	19% 42% 6% 17% 12% 4	3411
	21st to end	Day	24% 42% 5% 13% 15% 1	4101
April	1st to 10th	Day	16% 65% 3 9% 7% 1	2280
	11th to 20th	Day	17% 66% 3 7% 5% 1	2254
	21st to end	Day	15% 65% 4 10% 6% 1	2280
May	1st to 10th	Day	22% 43% 7% 18% 9%	3800
	11th to 20th	Day	25% 43% 11% 15% 6%	4085
	21st to end	Day	26% 44% 7% 15% 7% 1	4582
June	1st to 10th	Day	15% 67% 4 6% 7% 1	2660
	11th to 20th	Day	12% 66% 6% 9% 6%	2660
	21st to end	Day	14% 65% 6% 10% 4	2660
July	1st to 10th	Day	23% 38% 12% 21% 5%	4371
	11th to 20th	Day	26% 37% 8% 25% 3	4305
	21st to end	Day	40% 36% 6% 14% 4	4246
August	1st to 10th	Day	12% 38% 11% 20% 18% 2	3773
	11th to 20th	Day	20% 37% 11% 18% 12% 1	3765
	21st to end	Day	17% 37% 8% 16% 21% 1	4179
September	1st to 10th	Day	12% 62% 4 13% 7% 2	2280
	11th to 20th	Day	12% 61% 6% 9% 10% 2	2188
	21st to end	Day	16% 60% 5% 11% 6% 2	2090
October	1st to 10th	Day	8% 37% 3 8% 26% 19%	3385
	11th to 20th	Day	8% 36% 2 14% 27% 13%	3140
	21st to end	Day	15% 36% 2 19% 22% 7%	3428
November	1st to 10th	Day	20% 56% 3 7% 10% 3	1762
	11th to 20th	Day	14% 57% 3 8% 13% 4	1800
	21st to end	Day	20% 57% 3 8% 11% 1	1797
December	1st to 10th	Day	21% 60% 2 8% 7% 2	1710
	11th to 20th	Day	21% 48% 2 11% 15% 2	1963
	21st to end	Day	31% 40% 7% 13% 9% 1	2783
January	1st to 10th	Night	31% 37% 3 12% 16% 1	4392
	11th to 20th	Night	27% 38% 5% 13% 14% 4	4120
	21st to end	Night	29% 39% 4 15% 11% 2	4518
February	1st to 10th	Night	18% 64% 3 7% 6% 1	2280
	11th to 20th	Night	19% 64% 3 7% 6% 1	2219
	21st to end	Night	17% 65% 3 7% 6% 4	1884
March	1st to 10th	Night	33% 42% 6% 6% 8% 5%	3733
	11th to 20th	Night	18% 41% 5% 16% 13% 7%	3577
	21st to end	Night	23% 42% 6% 10% 18% 1	3516
April	1st to 10th	Night	14% 65% 3 9% 8% 1	1900
	11th to 20th	Night	16% 65% 3 9% 5% 1	1875
	21st to end	Night	12% 65% 4 9% 8% 2	1900
May	1st to 10th	Night	28% 43% 6% 14% 9% 1	3145
	11th to 20th	Night	24% 42% 9% 19% 6%	2813
	21st to end	Night	24% 45% 9% 15% 7% 1	2979
June	1st to 10th	Night	13% 67% 4 7% 8% 1	1520
	11th to 20th	Night	8% 66% 7% 10% 9%	1520
	21st to end	Night	9% 65% 7% 13% 7%	1520
July	1st to 10th	Night	22% 38% 16% 18% 5%	2490
	11th to 20th	Night	16% 36% 10% 31% 6% 1	2537
	21st to end	Night	36% 36% 6% 13% 8%	3074
August	1st to 10th	Night	7% 38% 5% 29% 20% 1	3132
	11th to 20th	Night	13% 38% 17% 19% 12% 1	3130
	21st to end	Night	12% 37% 9% 19% 21% 2	3476
September	1st to 10th	Night	10% 60% 4 13% 10% 3	1900
	11th to 20th	Night	10% 62% 5% 10% 12% 2	1971
	21st to end	Night	10% 60% 6% 15% 8% 2	2090
October	1st to 10th	Night	8% 37% 3 8% 25% 19%	3571
	11th to 20th	Night	8% 36% 2 10% 26% 19%	3779
	21st to end	Night	14% 36% 3 21% 14% 12%	4120
November	1st to 10th	Night	19% 56% 3 8% 12% 2	2534
	11th to 20th	Night	13% 57% 3 9% 13% 4	2600
	21st to end	Night	15% 57% 4 11% 12% 2	2599
December	1st to 10th	Night	20% 60% 3 8% 7% 2	2470
	11th to 20th	Night	18% 48% 3 13% 16% 2	3228
	21st to end	Night	28% 41% 8% 12% 8% 3	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	26% 24% 32% 14% 3	270
	11th to 20th	Day	33% 21% 33% 9% 2 1	270
	21st to end	Day	29% 27% 32% 10% 3	297
February	1st to 10th	Day	30% 22% 31% 13% 3 1	270
	11th to 20th	Day	36% 23% 30% 9% 1	270
	21st to end	Day	37% 29% 25% 6% 2	225
March	1st to 10th	Day	26% 21% 35% 13% 4	270
	11th to 20th	Day	25% 27% 34% 14%	270
	21st to end	Day	26% 19% 34% 14% 7%	468
April	1st to 10th	Day	24% 17% 32% 20% 7% 1	460
	11th to 20th	Day	21% 18% 32% 20% 7% 1	452
	21st to end	Day	22% 15% 30% 22% 10% 2	460
May	1st to 10th	Day	19% 17% 27% 25% 9% 3	463
	11th to 20th	Day	13% 8% 28% 29% 16% 5%	487
	21st to end	Day	9% 8% 26% 31% 18% 9%	583
June	1st to 10th	Day	12% 5% 20% 28% 25% 11%	680
	11th to 20th	Day	4 3 17% 37% 27% 12%	680
	21st to end	Day	6% 4 20% 35% 24% 11%	680
July	1st to 10th	Day	7% 3 13% 32% 30% 15%	671
	11th to 20th	Day	8% 2 13% 26% 34% 17%	668
	21st to end	Day	9% 2 10% 32% 32% 16%	695
August	1st to 10th	Day	5% 3 12% 31% 36% 12%	486
	11th to 20th	Day	10% 3 15% 31% 31% 10%	479
	21st to end	Day	12% 1 10% 23% 35% 19%	539
September	1st to 10th	Day	9% 3 11% 33% 36% 9%	490
	11th to 20th	Day	12% 3 14% 25% 32% 13%	490
	21st to end	Day	17% 6% 15% 31% 21% 10%	490
October	1st to 10th	Day	10% 3 24% 31% 28% 5%	434
	11th to 20th	Day	11% 12% 40% 26% 8% 2	300
	21st to end	Day	23% 14% 32% 24% 7% 1	330
November	1st to 10th	Day	20% 11% 28% 31% 9% 1	300
	11th to 20th	Day	13% 19% 37% 25% 6%	300
	21st to end	Day	26% 14% 30% 17% 10% 2	299
December	1st to 10th	Day	29% 21% 28% 18% 3 1	270
	11th to 20th	Day	26% 19% 31% 18% 6%	270
	21st to end	Day	25% 21% 39% 12% 3	297
January	1st to 10th	Night	23% 18% 33% 22% 4	950
	11th to 20th	Night	25% 19% 33% 20% 4	950
	21st to end	Night	22% 17% 36% 23% 2	1031
February	1st to 10th	Night	23% 17% 33% 22% 4	760
	11th to 20th	Night	24% 20% 32% 22% 2	743
	21st to end	Night	24% 23% 31% 19% 3	628
March	1st to 10th	Night	20% 16% 32% 28% 4	760
	11th to 20th	Night	22% 13% 35% 26% 4 1	628
	21st to end	Night	20% 14% 33% 24% 10%	627
April	1st to 10th	Night	15% 16% 34% 27% 8% 1	570
	11th to 20th	Night	18% 11% 33% 27% 10% 1	563
	21st to end	Night	14% 11% 35% 29% 10% 1	570
May	1st to 10th	Night	16% 8% 26% 34% 13% 2	570
	11th to 20th	Night	13% 6% 26% 34% 18% 4	561
	21st to end	Night	8% 2 23% 36% 26% 5%	617
June	1st to 10th	Night	8% 3 15% 37% 30% 6%	570
	11th to 20th	Night	4 1 14% 36% 42% 3	570
	21st to end	Night	5% 1 13% 38% 37% 6%	570
July	1st to 10th	Night	5% 1 12% 28% 45% 10%	555
	11th to 20th	Night	6% 2 11% 28% 40% 12%	552
	21st to end	Night	6% 1 9% 30% 43% 11%	624
August	1st to 10th	Night	4 1 7% 31% 48% 9%	567
	11th to 20th	Night	6% 2 6% 39% 41% 5%	564
	21st to end	Night	8% 1 9% 28% 44% 9%	627
September	1st to 10th	Night	7% 2 8% 39% 40% 5%	570
	11th to 20th	Night	11% 2 14% 32% 34% 7%	641
	21st to end	Night	11% 4 17% 35% 29% 4	760
October	1st to 10th	Night	9% 4 18% 34% 31% 4	760
	11th to 20th	Night	13% 8% 26% 34% 17% 2	760
	21st to end	Night	20% 9% 25% 31% 14% 1	836
November	1st to 10th	Night	13% 9% 25% 35% 17% 1	780
	11th to 20th	Night	13% 11% 33% 31% 12%	800
	21st to end	Night	20% 11% 31% 27% 10% 1	800
December	1st to 10th	Night	24% 12% 30% 27% 6%	760
	11th to 20th	Night	23% 14% 31% 27% 6%	897
	21st to end	Night	23% 17% 32% 24% 4	1045

Page generated at 2024-11-27 16:30:54. Version ac07

Copyright © 2024 Attilla Danko.