Magazine Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Magazine Mountain clear sky chart from 2005-11-05 to 2017-09-21.

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
52%
15696
26%
47127
19%
15649
59%
15649
33%
27355

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
36%
900
30%
2327
13%
895
47%
895
33%
1412
January16th to endNight
35%
960
31%
2496
11%
960
47%
960
35%
1507
February1st to 15thNight
32%
880
22%
2287
8%
876
40%
876
30%
1440
February16th to endNight
32%
587
28%
1849
12%
587
45%
587
29%
1051
March1st to 15thNight
40%
540
23%
1980
17%
540
48%
540
22%
1196
March16th to endNight
40%
576
20%
2112
18%
576
46%
576
23%
1298
April1st to 15thNight
41%
539
24%
1835
16%
539
54%
539
30%
1018
April16th to endNight
43%
540
23%
1800
18%
540
55%
540
29%
1048
May1st to 15thNight
51%
539
20%
1680
17%
539
58%
539
27%
1055
May16th to endNight
60%
563
21%
1685
22%
561
64%
561
33%
1016
June1st to 15thNight
76%
540
23%
1620
22%
540
79%
540
46%
844
June16th to endNight
78%
540
25%
1620
25%
540
80%
540
48%
829
July1st to 15thNight
74%
510
19%
1530
20%
510
76%
510
38%
876
July16th to endNight
85%
564
26%
1594
30%
531
86%
531
45%
840
August1st to 15thNight
77%
539
25%
1610
28%
536
79%
536
42%
878
August16th to endNight
76%
573
24%
1907
29%
573
76%
573
35%
1063
September1st to 15thNight
72%
540
27%
1803
30%
540
74%
540
35%
993
September16th to endNight
69%
532
33%
1903
34%
532
72%
532
35%
991
October1st to 15thNight
60%
660
31%
1980
26%
660
62%
660
39%
1101
October16th to endNight
55%
704
35%
2112
24%
704
63%
704
42%
1109
November1st to 15thNight
53%
700
32%
2100
23%
700
61%
700
37%
1168
November16th to endNight
42%
810
30%
2302
18%
810
52%
810
31%
1397
December1st to 15thNight
40%
900
22%
2499
12%
900
47%
900
30%
1567
December16th to endNight
37%
960
25%
2496
12%
960
45%
960
26%
1658

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
12%5%25%5%3445%7%44%
47716
Night
11%424423347%51%
47323
TransparencyDay
38%410%23%18%4
47416
Night
33%310%25%21%5%
47128
SeeingDay
12%6%18%26%26%10%
5740
Night
14%7%19%33%22%2
15697

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
16%6%13223235%50%
1611
16th to endDay
13%6%24413345%49%
1728
February1st to 15thDay
15%7%35%323325%48%
1575
16th to endDay
14%7%36%423346%43%
1632
March1st to 15thDay
17%6%24424245%44%
1980
16th to endDay
17%7%35%5%23345%38%
2110
April1st to 15thDay
13%5%35%434346%45%
2112
16th to endDay
17%6%25%5%34446%39%
2160
May1st to 15thDay
16%7%35%5%34445%39%
2268
16th to endDay
11%5%36%6%36%5%6%7%36%
2430
June1st to 15thDay
7%426%6%36%6%7%8%40%
2340
16th to endDay
6%3245%35%6%6%10%44%
2340
July1st to 15thDay
8%5%35%7%47%6%7%9%34%
2340
16th to endDay
5%2246%5%6%7%8%10%40%
2466
August1st to 15thDay
8%4245%45%6%7%10%40%
2340
16th to endDay
8%4246%36%5%6%8%41%
2295
September1st to 15thDay
13%5%2442435%7%46%
2154
16th to endDay
9%41442445%6%51%
1838
October1st to 15thDay
12%5%26%424235%50%
1650
16th to endDay
13%41322323458%
1760
November1st to 15thDay
9%424323345%55%
1758
16th to endDay
14%7%25%313325%51%
1649
December1st to 15thDay
15%5%24423346%46%
1452
16th to endDay
17%6%34424235%44%
1728
January1st to 15thNight
15%423322235%54%
2327
16th to endNight
12%42442333454%
2496
February1st to 15thNight
14%7%24412345%48%
2278
16th to endNight
11%6%24322337%51%
1849
March1st to 15thNight
17%6%24324246%43%
1980
16th to endNight
17%5%35%423245%43%
2112
April1st to 15thNight
10%3245%2445%6%50%
1835
16th to endNight
11%6%24324446%48%
1800
May1st to 15thNight
13%425%334447%45%
1679
16th to endNight
7%6%345%2446%9%45%
1683
June1st to 15thNight
421332345%8%59%
1620
16th to endNight
421321436%9%58%
1620
July1st to 15thNight
3425%5%35%5%7%11%44%
1620
16th to endNight
32124345%7%11%53%
1702
August1st to 15thNight
42145%3446%10%51%
1620
16th to endNight
6%323435%6%7%10%46%
1907
September1st to 15thNight
10%5%1332335%6%53%
1803
16th to endNight
7%41442346%6%54%
1903
October1st to 15thNight
9%5%14422345%55%
1980
16th to endNight
12%31221223462%
2112
November1st to 15thNight
9%323314346%55%
2100
16th to endNight
15%5%2431323452%
2302
December1st to 15thNight
16%6%24423336%46%
2499
16th to endNight
17%6%35%423335%45%
2496

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
37%27%26%20%5%
1612
16th to endDay
37%17%27%21%3
1728
February1st to 15thDay
40%29%24%17%4
1576
16th to endDay
42%28%23%17%5%
1632
March1st to 15thDay
43%28%20%16%7%
1980
16th to endDay
47%39%24%13%2
2112
April1st to 15thDay
39%310%22%19%4
2112
16th to endDay
44%47%20%19%2
2160
May1st to 15thDay
47%48%17%18%2
2268
16th to endDay
43%5%12%23%13%1
2434
June1st to 15thDay
37%6%12%25%17%
2340
16th to endDay
32%6%14%25%18%2
2340
July1st to 15thDay
40%6%13%27%10%1
2201
16th to endDay
33%7%15%29%13%1
2311
August1st to 15thDay
36%6%13%25%16%2
2326
16th to endDay
38%6%15%20%15%3
2295
September1st to 15thDay
37%5%9%23%15%8%
2154
16th to endDay
31%310%23%24%5%
1838
October1st to 15thDay
37%27%21%23%8%
1650
16th to endDay
29%26%24%26%9%
1760
November1st to 15thDay
30%38%28%21%7%
1758
16th to endDay
37%26%22%24%5%
1649
December1st to 15thDay
39%211%23%18%4
1452
16th to endDay
44%26%23%18%4
1728
January1st to 15thNight
34%27%23%28%4
2327
16th to endNight
33%17%26%23%6%
2496
February1st to 15thNight
37%28%27%18%5%
2288
16th to endNight
34%29%28%18%6%
1849
March1st to 15thNight
42%310%17%20%6%
1980
16th to endNight
43%28%24%17%3
2112
April1st to 15thNight
33%311%21%20%8%
1835
16th to endNight
35%49%23%23%3
1800
May1st to 15thNight
38%5%10%20%18%5%
1680
16th to endNight
33%6%17%26%14%1
1685
June1st to 15thNight
22%5%12%32%24%2
1620
16th to endNight
21%414%28%25%5%
1620
July1st to 15thNight
28%6%17%28%16%2
1530
16th to endNight
22%6%16%34%18%2
1594
August1st to 15thNight
26%415%31%18%2
1610
16th to endNight
29%6%15%25%18%3
1907
September1st to 15thNight
31%49%25%20%8%
1803
16th to endNight
28%47%25%25%7%
1903
October1st to 15thNight
31%210%20%23%11%
1980
16th to endNight
26%15%22%30%11%
2112
November1st to 15thNight
29%37%25%23%10%
2100
16th to endNight
36%25%21%27%6%
2302
December1st to 15thNight
40%29%22%19%5%
2499
16th to endNight
43%27%22%18%5%
2496

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
18%10%42%20%8%
90
16th to endDay
15%19%36%16%9%2
96
February1st to 15thDay
8%24%36%22%6%1
90
16th to endDay
14%17%39%18%8%1
81
March1st to 15thDay
23%22%33%20%1
90
16th to endDay
12%23%31%21%10%
96
April1st to 15thDay
15%19%24%24%14%1
231
16th to endDay
25%8%24%23%14%3
270
May1st to 15thDay
17%9%27%26%17%1
405
16th to endDay
13%6%26%31%17%5%
517
June1st to 15thDay
10%214%25%37%9%
495
16th to endDay
6%314%33%29%11%
495
July1st to 15thDay
7%114%32%30%13%
475
16th to endDay
4422%42%26%
515
August1st to 15thDay
10%17%28%36%15%
493
16th to endDay
10%15%22%42%16%
335
September1st to 15thDay
10%17%18%41%20%
309
16th to endDay
7%17%37%29%16%
105
October1st to 15thDay
7%218%41%26%3
90
16th to endDay
17%5%17%30%21%7%
96
November1st to 15thDay
10%6%23%32%24%3
90
16th to endDay
30%17%22%12%16%1
90
December1st to 15thDay
15%11%38%16%14%3
90
16th to endDay
19%14%33%26%6%
96
January1st to 15thNight
20%14%25%32%8%
900
16th to endNight
15%12%32%34%4
960
February1st to 15thNight
18%14%29%33%4
880
16th to endNight
17%14%31%32%3
587
March1st to 15thNight
21%10%23%39%5%
540
16th to endNight
19%7%26%35%10%1
576
April1st to 15thNight
13%10%30%33%12%
539
16th to endNight
14%8%28%34%13%
540
May1st to 15thNight
15%5%22%38%16%1
540
16th to endNight
11%416%37%27%3
563
June1st to 15thNight
429%37%41%3
540
16th to endNight
5%17%32%47%5%
540
July1st to 15thNight
318%31%48%5%
510
16th to endNight
4225%53%13%
564
August1st to 15thNight
5%5%28%49%10%
539
16th to endNight
8%1426%52%8%
573
September1st to 15thNight
12%6%26%47%5%
540
16th to endNight
9%210%35%37%6%
532
October1st to 15thNight
13%416%33%28%3
660
16th to endNight
13%7%19%34%22%1
704
November1st to 15thNight
10%9%20%38%20%1
700
16th to endNight
19%10%22%31%15%
810
December1st to 15thNight
21%9%25%35%8%
900
16th to endNight
22%12%21%36%6%
960
Page generated at 2017-09-22 06:35:39. Version ac04

Copyright 2017 A. Danko


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