Sachigo Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sachigo Lake clear sky chart from 2005-11-05 to 2017-11-30.

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 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
31%
16107
7%
47686
4%
16064
34%
16064
13%
37112

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
27%
900
5%
2759
4%
895
28%
895
9%
2313
January16th to endNight
29%
960
5%
2880
3%
960
31%
960
9%
2386
February1st to 15thNight
33%
875
8%
2384
5%
875
35%
875
14%
1910
February16th to endNight
39%
789
7%
2051
4%
789
41%
789
13%
1693
March1st to 15thNight
37%
677
12%
2117
10%
677
41%
677
14%
1585
March16th to endNight
38%
576
15%
2046
12%
576
46%
576
17%
1415
April1st to 15thNight
42%
539
15%
1759
13%
539
48%
539
24%
1146
April16th to endNight
39%
540
14%
1496
6%
540
44%
540
30%
964
May1st to 15thNight
30%
540
5%
1440
2%
540
32%
540
20%
1072
May16th to endNight
33%
452
0%
1204
0%
450
34%
450
20%
894
June1st to 15thNight
40%
360
0%
1080
0%
360
40%
360
22%
723
June16th to endNight
39%
360
0%
1080
0%
360
39%
360
19%
758
July1st to 15thNight
44%
361
0%
1041
0%
361
44%
361
25%
691
July16th to endNight
45%
564
1%
1239
1%
531
46%
531
31%
857
August1st to 15thNight
48%
539
7%
1406
5%
536
50%
536
26%
977
August16th to endNight
38%
573
10%
1675
6%
573
41%
573
22%
1156
September1st to 15thNight
30%
540
6%
1800
3%
540
35%
540
16%
1275
September16th to endNight
28%
613
9%
1966
6%
613
33%
613
14%
1470
October1st to 15thNight
19%
720
9%
2160
4%
720
23%
720
10%
1761
October16th to endNight
18%
844
4%
2542
1%
844
20%
844
5%
2241
November1st to 15thNight
14%
950
5%
2661
1%
950
18%
950
6%
2337
November16th to endNight
16%
975
4%
2948
2%
975
18%
975
5%
2584
December1st to 15thNight
28%
900
5%
2880
2%
900
32%
900
8%
2386
December16th to endNight
29%
960
7%
3072
5%
960
32%
960
9%
2518

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
15%10%48%6%46%5%5%6%26%
48760
Night
14%12%5%8%7%46%6%5%5%22%
47821
Cloud CoverDay
12%9%37%6%319%45%5%22%
48769
Night
11%11%47%6%319%5%45%19%
47825
TransparencyDay
57%411%17%7%
48413
Night
61%410%16%5%
47686
SeeingDay
21%11%30%23%10%2
6498
Night
20%8%29%27%11%1
16112

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
9%11%10%14%11%48%7%6%410%
1179
16th to endDay
11%11%6%10%10%5%9%11%8%5%10%
1344
February1st to 15thDay
38%49%7%411%12%10%9%19%
1478
16th to endDay
5%12%6%9%8%49%10%8%6%19%
1422
March1st to 15thDay
10%9%39%7%45%7%7%6%27%
1844
16th to endDay
8%12%48%7%46%5%6%6%29%
2178
April1st to 15thDay
9%9%47%6%46%45%7%34%
2187
16th to endDay
7%9%35%435%5%5%7%42%
2463
May1st to 15thDay
18%11%48%7%2445%6%26%
2511
16th to endDay
21%8%36%5%3445%7%30%
2908
June1st to 15thDay
15%8%36%6%35%46%6%34%
2880
16th to endDay
18%7%26%6%35%45%5%32%
2880
July1st to 15thDay
17%6%36%6%46%6%6%7%28%
2856
16th to endDay
14%6%26%5%46%5%7%8%32%
2845
August1st to 15thDay
17%6%27%5%35%5%5%6%34%
2546
16th to endDay
22%6%25%5%245%46%33%
2524
September1st to 15thDay
21%10%25%434447%29%
2160
16th to endDay
25%13%36%5%3444424%
1979
October1st to 15thDay
21%20%48%6%34335%17%
1800
16th to endDay
22%24%8%9%6%3323411%
1680
November1st to 15thDay
18%20%8%13%7%4433310%
1527
16th to endDay
11%17%6%14%12%7%8%5%348%
1337
December1st to 15thDay
8%17%6%12%10%6%8%6%7%7%9%
1080
16th to endDay
12%14%7%12%8%5%7%6%6%5%12%
1152
January1st to 15thNight
8%13%7%13%10%6%9%7%7%5%10%
2759
16th to endNight
9%13%6%10%9%5%9%10%9%6%8%
2880
February1st to 15thNight
6%8%48%8%6%14%12%7%319%
2381
16th to endNight
5%11%7%11%9%6%11%7%6%6%15%
2051
March1st to 15thNight
11%11%48%7%48%6%47%25%
2104
16th to endNight
9%12%38%6%35%5%47%32%
2046
April1st to 15thNight
10%8%36%6%45%45%5%40%
1759
16th to endNight
9%9%36%413445%46%
1496
May1st to 15thNight
20%11%36%5%33445%30%
1440
16th to endNight
21%8%36%5%25%46%5%30%
1203
June1st to 15thNight
18%5%25%5%3445%7%37%
1080
16th to endNight
19%7%36%5%35%45%8%31%
1080
July1st to 15thNight
16%5%25%436%5%6%9%33%
1102
16th to endNight
13%5%145%25%5%6%9%39%
1323
August1st to 15thNight
16%6%35%5%1445%7%38%
1413
16th to endNight
22%6%245%24446%36%
1675
September1st to 15thNight
22%8%26%43445%7%30%
1800
16th to endNight
26%9%35%5%23445%29%
1966
October1st to 15thNight
28%17%5%6%42333321%
2160
16th to endNight
24%23%8%8%6%2333311%
2542
November1st to 15thNight
19%20%8%12%8%3333312%
2661
16th to endNight
13%18%7%13%11%6%6%43410%
2948
December1st to 15thNight
8%12%7%12%10%6%8%8%6%6%11%
2880
16th to endNight
12%14%5%12%9%47%8%7%5%12%
3072

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
49%7%13%10%325%6%5%48%
1180
16th to endDay
8%10%39%8%5%24%10%7%47%
1344
February1st to 15thDay
37%38%6%324%10%9%6%15%
1478
16th to endDay
412%5%8%6%422%9%6%5%15%
1422
March1st to 15thDay
7%7%210%6%221%6%5%5%23%
1854
16th to endDay
5%12%37%6%422%5%45%23%
2176
April1st to 15thDay
6%8%35%6%322%445%28%
2187
16th to endDay
6%8%343221%445%33%
2463
May1st to 15thDay
13%10%37%5%320%345%22%
2511
16th to endDay
15%7%25%4220%345%27%
2908
June1st to 15thDay
12%6%25%5%220%45%5%28%
2880
16th to endDay
14%7%25%5%321%345%26%
2880
July1st to 15thDay
14%5%245%321%5%5%6%24%
2856
16th to endDay
11%5%25%5%321%46%7%26%
2845
August1st to 15thDay
15%6%16%5%313%45%6%30%
2546
16th to endDay
21%5%25%5%212%445%29%
2524
September1st to 15thDay
19%10%25%4312%437%25%
2160
16th to endDay
22%12%36%5%311%43423%
1979
October1st to 15thDay
18%19%37%6%312%33416%
1800
16th to endDay
19%22%7%9%6%312%23410%
1680
November1st to 15thDay
15%19%7%11%7%317%3229%
1527
16th to endDay
8%15%5%14%10%6%20%4246%
1337
December1st to 15thDay
414%311%7%5%23%6%7%6%8%
1080
16th to endDay
8%12%411%7%5%22%5%6%5%9%
1152
January1st to 15thNight
410%5%12%8%6%24%7%6%48%
2759
16th to endNight
6%11%49%8%5%24%8%8%5%6%
2880
February1st to 15thNight
5%7%47%7%5%27%11%5%315%
2374
16th to endNight
5%10%6%9%7%5%24%7%5%413%
2051
March1st to 15thNight
7%9%37%6%324%6%36%21%
2117
16th to endNight
7%11%28%5%321%445%26%
2044
April1st to 15thNight
7%7%35%5%321%44433%
1759
16th to endNight
7%9%35%4119%33438%
1496
May1st to 15thNight
14%10%25%5%119%335%26%
1439
16th to endNight
14%8%244221%45%427%
1204
June1st to 15thNight
13%5%143220%446%32%
1080
16th to endNight
14%5%25%4321%447%26%
1080
July1st to 15thNight
12%415%3221%45%8%30%
1102
16th to endNight
9%4144221%45%8%32%
1323
August1st to 15thNight
14%6%244213%45%6%35%
1413
16th to endNight
20%5%345%212%346%31%
1675
September1st to 15thNight
21%7%25%4212%45%6%26%
1800
16th to endNight
23%9%25%4211%33428%
1966
October1st to 15thNight
25%16%46%3212%22320%
2160
16th to endNight
20%22%7%8%5%211%32311%
2542
November1st to 15thNight
15%18%7%11%7%216%33311%
2661
16th to endNight
10%16%5%12%10%5%20%3339%
2948
December1st to 15thNight
6%10%5%9%9%5%24%8%5%5%10%
2880
16th to endNight
7%12%411%7%422%7%6%5%9%
3072

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
72%5%8%12%2
1180
16th to endDay
68%5%7%13%5%
1344
February1st to 15thDay
52%6%12%21%6%
1479
16th to endDay
61%49%16%7%
1422
March1st to 15thDay
53%5%14%19%6%
1854
16th to endDay
55%410%19%8%2
2178
April1st to 15thDay
49%411%23%11%
2187
16th to endDay
40%48%26%17%1
2463
May1st to 15thDay
58%39%19%8%
2511
16th to endDay
54%37%22%9%1
2912
June1st to 15thDay
48%5%8%20%15%
2880
16th to endDay
52%5%11%19%9%1
2880
July1st to 15thDay
51%7%13%20%6%1
2689
16th to endDay
47%6%19%18%6%
2666
August1st to 15thDay
48%6%18%21%4
2529
16th to endDay
50%5%16%20%6%
2524
September1st to 15thDay
54%418%17%3
2160
16th to endDay
62%412%15%3
1979
October1st to 15thDay
70%310%10%4
1800
16th to endDay
78%39%6%1
1680
November1st to 15thDay
80%37%6%2
1527
16th to endDay
79%36%8%2
1337
December1st to 15thDay
71%410%10%2
1080
16th to endDay
70%38%13%4
1152
January1st to 15thNight
71%48%13%2
2759
16th to endNight
68%5%7%13%4
2880
February1st to 15thNight
62%5%9%17%4
2384
16th to endNight
66%5%7%15%5%
2051
March1st to 15thNight
58%412%16%8%
2117
16th to endNight
52%48%22%9%3
2046
April1st to 15thNight
45%39%26%14%
1759
16th to endNight
39%38%26%20%
1496
May1st to 15thNight
54%48%22%9%
1440
16th to endNight
53%48%18%12%2
1204
June1st to 15thNight
45%5%6%23%18%
1080
16th to endNight
50%5%13%18%10%2
1080
July1st to 15thNight
43%5%15%25%8%1
1041
16th to endNight
40%6%17%27%7%
1239
August1st to 15thNight
44%6%17%25%5%
1406
16th to endNight
48%417%22%5%
1675
September1st to 15thNight
52%5%20%17%3
1800
16th to endNight
58%413%19%3
1966
October1st to 15thNight
69%38%14%3
2160
16th to endNight
78%38%7%1
2542
November1st to 15thNight
77%39%5%3
2661
16th to endNight
78%38%8%1
2948
December1st to 15thNight
67%7%10%12%1
2880
16th to endNight
68%5%10%12%3
3072

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
5%11%40%31%10%1
77
16th to endDay
33%331%21%8%2
96
February1st to 15thDay
312%46%27%8%1
90
16th to endDay
9%14%32%27%14%1
81
March1st to 15thDay
12%15%33%25%10%3
90
16th to endDay
11%16%33%19%13%5%
162
April1st to 15thDay
16%8%28%32%12%2
306
16th to endDay
14%14%35%21%9%3
450
May1st to 15thDay
22%12%31%21%8%2
468
16th to endDay
24%11%31%23%6%2
517
June1st to 15thDay
20%15%26%23%11%3
495
16th to endDay
24%9%29%24%11%2
495
July1st to 15thDay
17%9%31%27%11%2
475
16th to endDay
16%10%30%23%13%4
515
August1st to 15thDay
23%7%23%25%16%3
493
16th to endDay
24%9%24%26%12%2
514
September1st to 15thDay
29%6%31%24%7%
315
16th to endDay
34%12%30%16%5%
222
October1st to 15thDay
34%12%29%20%2
135
16th to endDay
34%12%34%13%6%
144
November1st to 15thDay
25%15%41%14%2
135
16th to endDay
21%16%41%13%6%2
99
December1st to 15thDay
23%10%28%26%10%1
60
16th to endDay
25%12%37%15%7%1
64
January1st to 15thNight
13%11%35%25%11%3
900
16th to endNight
16%12%29%32%8%
960
February1st to 15thNight
10%8%37%29%11%3
880
16th to endNight
11%5%30%32%17%3
789
March1st to 15thNight
16%9%28%27%16%1
677
16th to endNight
16%9%28%26%14%3
576
April1st to 15thNight
13%7%28%36%11%1
539
16th to endNight
14%10%31%30%10%2
540
May1st to 15thNight
26%7%30%24%10%
540
16th to endNight
26%6%28%27%9%
452
June1st to 15thNight
20%8%25%29%13%2
360
16th to endNight
19%7%27%33%11%1
360
July1st to 15thNight
17%429%32%15%
361
16th to endNight
15%427%34%15%3
564
August1st to 15thNight
20%320%33%19%1
539
16th to endNight
25%6%25%27%13%1
573
September1st to 15thNight
29%5%29%26%9%
540
16th to endNight
30%8%27%22%9%
613
October1st to 15thNight
38%8%26%20%41
720
16th to endNight
37%9%23%19%7%2
844
November1st to 15thNight
28%11%30%22%6%1
950
16th to endNight
23%12%32%21%8%
975
December1st to 15thNight
13%11%32%29%12%
900
16th to endNight
18%7%28%30%13%1
960
Page generated at 2017-12-01 11:13:40. Version ac04

Copyright 2017 A. Danko


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