Observatoire Laforge-1
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatoire Laforge-1 clear sky chart from 2005-11-05 to 2018-10-08.

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 TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(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

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
30%
16175
5%
50807
4%
16143
31%
16143
8%
42905

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
25%
1020
3%
3104
2%
1015
26%
1015
4%
2848
January16th to endNight
35%
910
8%
3022
6%
910
37%
910
6%
2606
February1st to 15thNight
42%
764
6%
2672
5%
761
44%
761
7%
2244
February16th to endNight
36%
683
7%
2155
7%
683
38%
683
9%
1803
March1st to 15thNight
42%
779
11%
2340
8%
779
45%
779
14%
1827
March16th to endNight
35%
832
10%
2176
5%
832
37%
832
13%
1792
April1st to 15thNight
34%
733
9%
1901
6%
733
35%
733
13%
1539
April16th to endNight
39%
467
12%
1623
12%
467
43%
467
16%
1211
May1st to 15thNight
33%
390
6%
1489
6%
390
35%
390
11%
1147
May16th to endNight
35%
406
0%
1359
0%
406
35%
406
18%
979
June1st to 15thNight
43%
390
0%
1170
0%
390
43%
390
21%
825
June16th to endNight
38%
390
0%
1170
0%
390
38%
390
18%
862
July1st to 15thNight
36%
370
0%
1110
0%
370
36%
370
15%
853
July16th to endNight
44%
408
1%
1306
0%
386
45%
386
13%
1023
August1st to 15thNight
42%
383
5%
1524
9%
381
42%
381
10%
1166
August16th to endNight
35%
532
6%
1774
6%
532
36%
532
12%
1407
September1st to 15thNight
26%
780
7%
1950
4%
780
28%
780
12%
1640
September16th to endNight
20%
777
6%
2139
3%
777
23%
777
10%
1779
October1st to 15thNight
17%
752
7%
2286
5%
752
20%
752
7%
1983
October16th to endNight
15%
768
3%
2496
3%
768
16%
768
4%
2288
November1st to 15thNight
14%
786
1%
2746
1%
786
15%
786
2%
2562
November16th to endNight
15%
825
2%
2925
2%
825
16%
825
2%
2730
December1st to 15thNight
16%
942
1%
3042
1%
942
17%
942
2%
2856
December16th to endNight
32%
1088
6%
3328
5%
1088
33%
1088
6%
2935

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 ForecastData
Points
Cloud CoverDay
20%14%6%9%7%45%5%45%16%
52360
Night
16%15%6%10%8%46%5%4415%
50946
TransparencyDay
69%6%8%11%3
52015
Night
70%6%8%10%3
50809
SeeingDay
28%7%22%22%13%5%
8304
Night
23%6%25%27%14%3
16177

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
11%17%8%12%10%6%8%7%6%44
1164
16th to endDay
5%13%7%14%11%6%10%8%9%47%
1552
February1st to 15thDay
29%5%11%13%9%13%13%10%44
1520
16th to endDay
6%13%7%13%10%8%10%11%6%47%
1601
March1st to 15thDay
7%9%6%10%10%6%9%9%9%5%14%
1940
16th to endDay
8%15%7%12%9%5%7%7%5%5%14%
2397
April1st to 15thDay
14%14%6%11%9%5%6%45%416%
2377
16th to endDay
13%14%7%10%8%3433325%
2624
May1st to 15thDay
22%16%6%10%6%2323420%
2792
16th to endDay
17%14%5%9%6%34447%23%
3103
June1st to 15thDay
18%11%35%5%345%46%30%
3120
16th to endDay
23%10%37%6%3445%6%24%
3120
July1st to 15thDay
27%10%48%6%34445%20%
3120
16th to endDay
28%11%48%7%45%445%15%
3129
August1st to 15thDay
26%11%46%6%35%5%45%18%
2679
16th to endDay
29%13%5%6%6%34446%16%
2765
September1st to 15thDay
29%14%48%6%2333417%
2340
16th to endDay
32%17%46%6%3234414%
2151
October1st to 15thDay
27%25%5%7%43333411%
1840
16th to endDay
32%22%9%8%5%222227%
1728
November1st to 15thDay
23%23%11%13%7%232226%
1439
16th to endDay
16%25%11%14%9%323226%
1365
December1st to 15thDay
12%18%7%15%13%7%7%6%325%
1246
16th to endDay
10%14%7%11%13%7%12%8%5%36%
1248
January1st to 15thNight
11%17%7%14%11%6%9%9%5%32
3104
16th to endNight
6%13%7%13%11%6%11%9%6%5%7%
3022
February1st to 15thNight
39%6%12%12%8%12%12%9%5%6%
2670
16th to endNight
7%15%6%10%11%6%8%8%7%5%11%
2155
March1st to 15thNight
6%10%6%10%8%5%8%9%7%7%18%
2327
16th to endNight
9%13%6%12%7%5%7%6%4420%
2176
April1st to 15thNight
13%14%7%9%8%46%44422%
1901
16th to endNight
12%12%6%8%7%4444430%
1623
May1st to 15thNight
22%13%5%8%6%35%23424%
1489
16th to endNight
13%12%5%8%5%34446%32%
1359
June1st to 15thNight
19%8%25%5%34447%34%
1170
16th to endNight
21%9%25%5%24447%32%
1170
July1st to 15thNight
24%7%36%5%445%46%26%
1170
16th to endNight
22%9%46%5%45%36%6%24%
1390
August1st to 15thNight
22%8%48%6%35%35%7%24%
1534
16th to endNight
25%10%38%6%33346%23%
1774
September1st to 15thNight
25%12%49%6%3433421%
1950
16th to endNight
30%14%47%423335%19%
2139
October1st to 15thNight
27%23%36%5%3333415%
2286
16th to endNight
30%22%7%10%6%232238%
2496
November1st to 15thNight
24%23%10%12%7%332325%
2746
16th to endNight
17%22%9%15%9%443226%
2925
December1st to 15thNight
11%19%10%17%13%6%7%5%215%
3042
16th to endNight
9%15%7%12%11%6%9%8%6%38%
3328

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
79%45%7%2
1165
16th to endDay
71%6%7%9%5%
1552
February1st to 15thDay
69%8%8%9%3
1522
16th to endDay
74%6%7%8%2
1601
March1st to 15thDay
62%7%7%15%6%
1950
16th to endDay
70%5%7%9%5%
2397
April1st to 15thDay
68%5%7%13%5%
2377
16th to endDay
64%48%16%6%
2624
May1st to 15thDay
69%36%14%5%
2792
16th to endDay
61%6%11%16%4
3107
June1st to 15thDay
54%6%10%19%9%
3120
16th to endDay
60%6%11%15%6%
3120
July1st to 15thDay
64%7%10%13%3
2951
16th to endDay
70%7%10%9%2
2950
August1st to 15thDay
65%9%12%11%1
2665
16th to endDay
69%7%11%9%1
2765
September1st to 15thDay
71%5%10%10%2
2340
16th to endDay
74%5%9%9%
2151
October1st to 15thDay
77%5%6%9%1
1840
16th to endDay
84%45%4
1728
November1st to 15thDay
85%45%2
1439
16th to endDay
86%3341
1365
December1st to 15thDay
83%7%6%2
1246
16th to endDay
78%5%7%6%1
1248
January1st to 15thNight
82%5%5%5%1
3104
16th to endNight
74%6%5%8%5%
3022
February1st to 15thNight
68%9%8%10%3
2672
16th to endNight
69%6%8%10%5%
2155
March1st to 15thNight
59%6%11%13%8%
2340
16th to endNight
66%46%15%6%
2176
April1st to 15thNight
64%48%14%6%1
1901
16th to endNight
56%5%7%18%10%
1623
May1st to 15thNight
65%26%17%8%
1489
16th to endNight
53%5%15%19%6%
1361
June1st to 15thNight
50%412%22%9%
1170
16th to endNight
51%8%10%19%10%
1170
July1st to 15thNight
57%7%11%19%4
1110
16th to endNight
58%9%15%15%1
1306
August1st to 15thNight
59%8%14%16%1
1524
16th to endNight
62%6%14%14%1
1774
September1st to 15thNight
66%6%10%14%2
1950
16th to endNight
68%5%11%11%3
2139
October1st to 15thNight
73%6%7%10%1
2286
16th to endNight
82%5%6%5%1
2496
November1st to 15thNight
85%45%21
2746
16th to endNight
84%5%431
2925
December1st to 15thNight
86%5%421
3042
16th to endNight
75%6%6%8%2
3328

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
8%11%35%26%14%3
90
16th to endDay
15%323%33%16%7%
96
February1st to 15thDay
16%31%33%23%4
90
16th to endDay
8%10%28%28%18%5%
203
March1st to 15thDay
12%321%31%22%8%
330
16th to endDay
14%6%29%28%15%5%
352
April1st to 15thDay
17%426%27%16%6%
330
16th to endDay
21%8%24%26%13%6%
319
May1st to 15thDay
26%8%22%21%15%5%
419
16th to endDay
23%6%26%28%12%2
657
June1st to 15thDay
27%421%22%17%6%
765
16th to endDay
28%8%20%24%13%3
765
July1st to 15thDay
33%7%18%21%12%6%
735
16th to endDay
34%418%21%15%5%
639
August1st to 15thDay
32%5%13%17%18%13%
358
16th to endDay
33%7%21%20%9%8%
396
September1st to 15thDay
41%10%20%17%6%3
375
16th to endDay
37%11%28%16%41
374
October1st to 15thDay
40%11%21%17%7%1
328
16th to endDay
45%10%16%12%10%4
288
November1st to 15thDay
39%7%29%16%5%1
119
16th to endDay
26%11%31%17%11%2
90
December1st to 15thDay
21%6%24%24%16%6%
90
16th to endDay
11%334%33%9%8%
96
January1st to 15thNight
18%7%26%25%16%5%
1020
16th to endNight
11%424%34%20%4
910
February1st to 15thNight
6%425%36%21%6%
764
16th to endNight
14%224%32%21%4
683
March1st to 15thNight
9%5%25%33%22%3
780
16th to endNight
14%5%30%30%14%3
832
April1st to 15thNight
20%5%25%30%15%2
733
16th to endNight
16%7%26%32%14%2
467
May1st to 15thNight
28%8%20%28%12%1
390
16th to endNight
21%6%29%34%8%
407
June1st to 15thNight
23%419%33%17%1
390
16th to endNight
26%5%21%31%13%1
390
July1st to 15thNight
27%6%21%29%12%2
370
16th to endNight
23%220%27%22%3
408
August1st to 15thNight
25%217%27%24%3
383
16th to endNight
29%421%27%15%2
532
September1st to 15thNight
33%9%24%22%9%
780
16th to endNight
38%9%26%20%41
777
October1st to 15thNight
39%10%27%15%6%
752
16th to endNight
41%7%20%16%10%3
768
November1st to 15thNight
35%10%24%17%8%3
786
16th to endNight
28%10%27%21%8%4
825
December1st to 15thNight
18%10%30%27%10%2
942
16th to endNight
17%423%31%19%4
1088
Page generated at 2018-10-09 10:39:15. Version ac04

Copyright 2018 A. Danko


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