Mitchell Secondary School
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mitchell Secondary School clear sky chart from 2005-11-05 to 2018-01-20.

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
47%
16601
24%
48479
14%
16560
54%
16560
37%
27892

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
38%
974
23%
2716
12%
970
47%
970
35%
1609
January16th to endNight
35%
940
27%
2713
13%
940
47%
940
37%
1518
February1st to 15thNight
34%
696
18%
2235
9%
696
45%
696
29%
1334
February16th to endNight
34%
632
22%
1894
8%
632
47%
632
31%
1134
March1st to 15thNight
39%
720
23%
2160
11%
720
50%
720
35%
1232
March16th to endNight
38%
639
21%
2001
12%
639
48%
639
31%
1187
April1st to 15thNight
36%
539
17%
1798
11%
539
47%
539
27%
1073
April16th to endNight
37%
540
17%
1757
12%
540
46%
540
24%
1120
May1st to 15thNight
45%
540
19%
1561
13%
540
50%
540
29%
990
May16th to endNight
46%
562
17%
1498
11%
561
49%
561
30%
990
June1st to 15thNight
50%
540
14%
1440
7%
540
54%
540
37%
872
June16th to endNight
60%
540
21%
1440
12%
540
65%
540
52%
781
July1st to 15thNight
67%
510
18%
1360
13%
510
68%
510
42%
809
July16th to endNight
75%
564
27%
1416
21%
531
75%
531
54%
739
August1st to 15thNight
68%
539
20%
1578
19%
536
70%
536
42%
856
August16th to endNight
67%
573
28%
1910
29%
573
73%
573
43%
953
September1st to 15thNight
61%
540
26%
1800
25%
540
69%
540
38%
954
September16th to endNight
62%
537
34%
1965
32%
537
71%
537
43%
926
October1st to 15thNight
49%
663
25%
2103
17%
663
56%
663
34%
1195
October16th to endNight
50%
873
32%
2409
16%
873
58%
873
43%
1337
November1st to 15thNight
47%
950
29%
2470
15%
950
54%
950
45%
1405
November16th to endNight
47%
975
32%
2613
16%
975
58%
975
45%
1448
December1st to 15thNight
34%
975
19%
2730
9%
975
43%
975
33%
1655
December16th to endNight
38%
1040
22%
2912
11%
1040
47%
1040
33%
1775

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
7%42432445%8%52%
49070
Night
6%5%2442445%7%52%
48651
Cloud CoverDay
6%42442445%8%52%
49068
Night
6%5%2442445%7%52%
48651
TransparencyDay
28%5%13%27%18%5%
48744
Night
29%5%14%27%17%4
48479
SeeingDay
10%6%26%30%20%4
6354
Night
9%5%32%40%11%
16611

By Month

Percentage Cloud Cover SW (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
36%26%5%245%48%49%
1552
16th to endDay
35%25%324446%56%
1625
February1st to 15thDay
6%7%46%434347%46%
1627
16th to endDay
5%6%36%4235%48%48%
1580
March1st to 15thDay
5%5%24424448%53%
1800
16th to endDay
9%5%245%245%5%9%46%
2220
April1st to 15thDay
10%5%2432445%7%47%
2150
16th to endDay
14%6%2443445%7%42%
2202
May1st to 15thDay
12%5%244245%5%7%46%
2388
16th to endDay
10%5%25%5%35%6%7%8%40%
2616
June1st to 15thDay
7%3144245%6%10%49%
2520
16th to endDay
221222445%7%64%
2520
July1st to 15thDay
5%313325%5%6%9%53%
2520
16th to endDay
42123245%6%10%55%
2656
August1st to 15thDay
4213325%6%7%9%52%
2370
16th to endDay
4313323348%61%
2292
September1st to 15thDay
8%313313345%60%
2160
16th to endDay
7%212212247%63%
1995
October1st to 15thDay
12%5%13224436%54%
1856
16th to endDay
5%31321345%7%60%
1802
November1st to 15thDay
5%32342445%9%55%
1718
16th to endDay
441231245%8%60%
1677
December1st to 15thDay
5%6%34415%45%8%50%
1560
16th to endDay
6%6%245%245%5%8%47%
1664
January1st to 15thNight
45%25%42445%8%50%
2716
16th to endNight
342442445%7%53%
2713
February1st to 15thNight
5%7%35%5%2445%9%47%
2225
16th to endNight
5%8%26%42345%6%50%
1894
March1st to 15thNight
45%35%42435%8%51%
2160
16th to endNight
8%7%25%423448%47%
2001
April1st to 15thNight
8%7%345%2345%8%46%
1798
16th to endNight
15%6%245%2445%5%42%
1757
May1st to 15thNight
12%5%25%5%3435%7%46%
1560
16th to endNight
12%4145%245%6%7%44%
1497
June1st to 15thNight
8%5%2333346%8%50%
1440
16th to endNight
2123345%6%11%58%
1440
July1st to 15thNight
5%215%435%48%9%50%
1440
16th to endNight
321132446%10%59%
1512
August1st to 15thNight
4213335%5%7%9%53%
1586
16th to endNight
421333435%7%60%
1910
September1st to 15thNight
8%41432335%7%55%
1800
16th to endNight
7%21231334464%
1965
October1st to 15thNight
13%313323346%52%
2103
16th to endNight
7%31332345%6%58%
2409
November1st to 15thNight
5%42332445%7%57%
2470
16th to endNight
45%1332345%8%58%
2613
December1st to 15thNight
5%6%25%43445%7%49%
2730
16th to endNight
5%6%35%42445%7%49%
2912

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
35%26%425%5%48%49%
1552
16th to endDay
35%25%333446%56%
1625
February1st to 15thDay
6%7%36%443447%46%
1627
16th to endDay
5%7%36%43345%8%48%
1580
March1st to 15thDay
5%5%2442445%8%53%
1800
16th to endDay
8%5%25%5%245%5%9%46%
2218
April1st to 15thDay
10%5%24325%45%8%47%
2150
16th to endDay
14%5%2443445%7%41%
2202
May1st to 15thDay
12%5%2442445%6%46%
2388
16th to endDay
10%5%245%35%6%7%8%39%
2616
June1st to 15thDay
7%314425%46%10%49%
2520
16th to endDay
221232345%8%64%
2520
July1st to 15thDay
5%313235%5%6%8%53%
2520
16th to endDay
42133245%6%10%55%
2656
August1st to 15thDay
4313325%6%7%9%52%
2370
16th to endDay
4313323348%61%
2292
September1st to 15thDay
8%213313346%60%
2160
16th to endDay
7%312312347%63%
1995
October1st to 15thDay
11%413224346%54%
1856
16th to endDay
5%31231345%7%60%
1802
November1st to 15thDay
432342436%9%55%
1718
16th to endDay
441231345%7%60%
1677
December1st to 15thDay
46%345%15%45%8%50%
1560
16th to endDay
6%6%245%245%5%8%47%
1664
January1st to 15thNight
45%25%5%2445%8%50%
2716
16th to endNight
343442446%7%53%
2713
February1st to 15thNight
46%35%6%2445%8%47%
2225
16th to endNight
5%8%26%42445%6%49%
1894
March1st to 15thNight
46%25%42335%8%51%
2160
16th to endNight
8%7%25%324448%47%
2001
April1st to 15thNight
8%6%345%2445%7%46%
1798
16th to endNight
15%6%245%2445%6%42%
1757
May1st to 15thNight
11%5%25%5%3345%6%46%
1560
16th to endNight
11%5%245%345%6%7%44%
1497
June1st to 15thNight
8%5%2343346%8%50%
1440
16th to endNight
2223245%5%11%58%
1440
July1st to 15thNight
5%3144345%8%9%50%
1440
16th to endNight
3223235%6%10%58%
1512
August1st to 15thNight
4213335%5%7%9%52%
1586
16th to endNight
321333435%8%59%
1910
September1st to 15thNight
8%42432235%7%55%
1800
16th to endNight
6%31221344464%
1965
October1st to 15thNight
13%313323346%52%
2103
16th to endNight
7%313333447%57%
2409
November1st to 15thNight
5%42332445%7%57%
2470
16th to endNight
45%1332335%8%58%
2613
December1st to 15thNight
5%6%25%5%3445%7%49%
2730
16th to endNight
5%6%35%43445%7%48%
2912

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
31%5%17%31%12%1
1553
16th to endDay
27%417%33%14%1
1625
February1st to 15thDay
37%5%16%26%10%2
1628
16th to endDay
34%5%15%29%11%3
1580
March1st to 15thDay
29%314%27%19%4
1800
16th to endDay
34%6%15%27%13%2
2220
April1st to 15thDay
35%415%28%12%3
2150
16th to endDay
40%5%14%21%16%2
2202
May1st to 15thDay
36%6%14%28%12%1
2388
16th to endDay
38%7%17%24%10%1
2620
June1st to 15thDay
29%7%15%26%17%4
2520
16th to endDay
17%410%29%28%9%
2520
July1st to 15thDay
26%5%10%24%21%11%
2371
16th to endDay
20%5%11%25%24%11%
2489
August1st to 15thDay
24%7%14%26%17%10%
2354
16th to endDay
22%38%23%29%12%
2292
September1st to 15thDay
23%48%21%27%14%
2160
16th to endDay
20%38%32%30%5%
1995
October1st to 15thDay
30%5%11%24%21%5%
1856
16th to endDay
21%414%31%20%6%
1802
November1st to 15thDay
25%414%29%19%7%
1718
16th to endDay
21%216%33%23%2
1677
December1st to 15thDay
30%5%18%31%12%1
1560
16th to endDay
33%5%18%30%11%1
1664
January1st to 15thNight
30%5%17%29%14%2
2716
16th to endNight
28%416%32%15%2
2713
February1st to 15thNight
34%6%18%29%9%1
2235
16th to endNight
33%5%14%29%13%3
1894
March1st to 15thNight
30%412%29%17%4
2160
16th to endNight
34%415%26%16%2
2001
April1st to 15thNight
36%5%16%24%13%3
1798
16th to endNight
41%5%11%24%15%1
1757
May1st to 15thNight
37%6%15%24%14%1
1561
16th to endNight
37%8%18%22%10%2
1498
June1st to 15thNight
30%6%21%24%14%3
1440
16th to endNight
19%6%15%29%22%6%
1440
July1st to 15thNight
28%6%14%25%17%8%
1360
16th to endNight
18%412%31%21%10%
1416
August1st to 15thNight
24%6%19%26%15%8%
1578
16th to endNight
23%410%22%27%11%
1910
September1st to 15thNight
27%410%25%21%11%
1800
16th to endNight
22%37%33%25%7%
1965
October1st to 15thNight
32%413%22%22%4
2103
16th to endNight
25%411%28%21%8%
2409
November1st to 15thNight
25%312%26%24%6%
2470
16th to endNight
24%413%33%19%4
2613
December1st to 15thNight
32%5%17%30%12%1
2730
16th to endNight
33%6%18%28%12%
2912

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%436%30%17%6%
135
16th to endDay
9%241%30%12%3
109
February1st to 15thDay
11%17%46%21%3
90
16th to endDay
8%16%34%25%14%
81
March1st to 15thDay
47%38%35%11%2
90
16th to endDay
11%14%36%26%9%1
268
April1st to 15thDay
15%15%38%20%8%1
269
16th to endDay
22%16%25%23%11%1
312
May1st to 15thDay
15%7%25%29%17%3
468
16th to endDay
18%7%23%29%17%3
517
June1st to 15thDay
9%6%25%30%21%6%
495
16th to endDay
4426%38%24%2
495
July1st to 15thDay
8%219%32%30%6%
475
16th to endDay
6%218%33%33%5%
515
August1st to 15thDay
7%121%38%25%4
410
16th to endDay
6%423%31%21%12%
332
September1st to 15thDay
7%5%20%34%23%8%
315
16th to endDay
10%5%24%28%22%9%
150
October1st to 15thDay
15%328%21%24%6%
135
16th to endDay
9%8%29%26%19%6%
144
November1st to 15thDay
3322%41%18%10%
135
16th to endDay
14%9%32%31%11%
135
December1st to 15thDay
8%13%46%21%8%
135
16th to endDay
12%442%31%8%
144
January1st to 15thNight
6%10%39%31%10%1
975
16th to endNight
6%10%43%33%6%
940
February1st to 15thNight
7%5%45%32%7%
704
16th to endNight
10%8%41%34%5%
632
March1st to 15thNight
7%7%39%35%9%
720
16th to endNight
13%7%35%37%5%
639
April1st to 15thNight
12%9%37%35%5%
539
16th to endNight
19%7%29%35%7%
540
May1st to 15thNight
15%6%27%37%13%
540
16th to endNight
14%329%38%13%
563
June1st to 15thNight
11%5%28%41%12%
540
16th to endNight
3230%53%10%
540
July1st to 15thNight
7%116%52%22%
510
16th to endNight
3114%55%24%
564
August1st to 15thNight
5%18%53%20%
539
16th to endNight
4120%53%19%
573
September1st to 15thNight
10%220%42%22%1
540
16th to endNight
8%124%45%18%
537
October1st to 15thNight
15%328%38%12%
663
16th to endNight
8%431%40%13%
873
November1st to 15thNight
7%8%33%39%11%
950
16th to endNight
7%6%34%43%7%
975
December1st to 15thNight
8%8%42%34%5%
975
16th to endNight
9%6%39%37%6%
1040
Page generated at 2018-01-21 10:19:33. Version ac04

Copyright 2018 A. Danko


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