Big Rapids
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Rapids clear sky chart from 2005-11-05 to 2017-09-16.

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
33%
16018
15%
46808
8%
15976
39%
15976
20%
32777

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
15%
900
7%
2506
2%
895
19%
895
9%
2117
January16th to endNight
17%
960
7%
2688
2%
960
20%
960
10%
2209
February1st to 15thNight
17%
730
10%
2240
4%
730
23%
730
11%
1760
February16th to endNight
21%
631
13%
1893
5%
631
28%
631
13%
1440
March1st to 15thNight
28%
720
16%
2134
9%
720
34%
720
20%
1483
March16th to endNight
30%
729
18%
2073
10%
729
37%
729
22%
1405
April1st to 15thNight
28%
539
15%
1797
10%
539
36%
539
17%
1230
April16th to endNight
31%
540
20%
1629
9%
540
41%
540
24%
1055
May1st to 15thNight
34%
540
16%
1620
7%
540
42%
540
24%
1097
May16th to endNight
38%
562
17%
1536
8%
561
47%
561
31%
983
June1st to 15thNight
44%
540
14%
1440
8%
540
48%
540
33%
906
June16th to endNight
50%
540
15%
1440
8%
540
55%
540
36%
896
July1st to 15thNight
62%
510
17%
1360
13%
510
65%
510
46%
758
July16th to endNight
56%
564
17%
1417
11%
531
61%
531
43%
827
August1st to 15thNight
60%
539
23%
1581
17%
536
65%
536
40%
876
August16th to endNight
59%
573
23%
1807
19%
573
64%
573
35%
1028
September1st to 15thNight
56%
609
24%
1869
19%
609
62%
609
36%
1056
September16th to endNight
54%
661
22%
1826
15%
661
59%
661
34%
1114
October1st to 15thNight
43%
660
22%
1853
15%
660
49%
660
28%
1198
October16th to endNight
22%
704
12%
2288
6%
704
31%
704
16%
1627
November1st to 15thNight
30%
700
18%
2276
13%
700
37%
700
19%
1549
November16th to endNight
21%
720
10%
2340
5%
720
28%
720
11%
1815
December1st to 15thNight
14%
887
5%
2507
2%
887
17%
887
9%
2111
December16th to endNight
13%
960
8%
2688
2%
960
19%
960
10%
2237

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
14%9%47%6%35%45%7%31%
47959
Night
14%9%47%5%3445%6%33%
46976
Cloud CoverDay
14%9%47%6%35%45%7%32%
47968
Night
14%9%47%5%3445%6%33%
46981
TransparencyDay
51%311%21%10%1
47645
Night
50%312%21%10%1
46808
SeeingDay
17%9%28%25%13%5%
6006
Night
19%9%30%28%10%1
16022

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
16%16%7%13%10%5%5%445%10%
1432
16th to endDay
11%18%12%13%10%6%5%4348%
1536
February1st to 15thDay
13%14%8%10%11%5%7%5%4414%
1619
16th to endDay
12%15%7%10%10%46%5%45%17%
1580
March1st to 15thDay
14%11%5%8%6%35%448%27%
1814
16th to endDay
15%10%47%7%345%45%31%
2160
April1st to 15thDay
19%13%45%424346%30%
2151
16th to endDay
15%9%36%6%3445%7%34%
2329
May1st to 15thDay
18%8%35%5%2446%7%34%
2331
16th to endDay
12%5%35%5%3446%8%41%
2578
June1st to 15thDay
13%6%36%5%25%5%5%7%38%
2520
16th to endDay
11%426%5%36%5%5%8%39%
2520
July1st to 15thDay
6%425%435%5%6%9%45%
2520
16th to endDay
9%5%246%35%5%5%9%42%
2655
August1st to 15thDay
8%6%25%6%36%6%7%9%38%
2370
16th to endDay
12%6%25%5%25%45%7%41%
2393
September1st to 15thDay
13%425%435%46%8%42%
2079
16th to endDay
12%6%35%5%345%5%8%39%
1824
October1st to 15thDay
18%8%46%5%34346%35%
1774
16th to endDay
22%12%47%7%345%45%24%
1584
November1st to 15thDay
13%10%5%7%5%2435%6%34%
1582
16th to endDay
19%18%6%8%6%3435%5%19%
1620
December1st to 15thDay
16%16%11%12%8%45%32414%
1452
16th to endDay
21%17%10%11%8%3443410%
1536
January1st to 15thNight
18%15%7%10%8%45%43316%
2506
16th to endNight
11%14%9%12%9%5%6%5%6%6%13%
2688
February1st to 15thNight
12%14%7%9%9%46%43422%
2238
16th to endNight
15%13%5%9%8%45%5%46%22%
1893
March1st to 15thNight
15%8%46%5%35%447%33%
2121
16th to endNight
14%7%46%5%3445%7%36%
2073
April1st to 15thNight
18%10%45%5%2435%6%32%
1797
16th to endNight
18%7%25%22346%6%40%
1629
May1st to 15thNight
15%6%346%36%5%5%8%34%
1620
16th to endNight
10%6%35%43435%8%44%
1534
June1st to 15thNight
11%5%25%5%2446%8%43%
1440
16th to endNight
9%325%5%246%6%9%44%
1440
July1st to 15thNight
5%323325%45%9%54%
1440
16th to endNight
7%214425%46%8%52%
1513
August1st to 15thNight
5%424425%46%10%51%
1590
16th to endNight
10%424323446%52%
1807
September1st to 15thNight
11%313323447%52%
1869
16th to endNight
11%415%335%35%8%47%
1826
October1st to 15thNight
17%6%25%32345%6%41%
1853
16th to endNight
20%9%47%6%24336%31%
2288
November1st to 15thNight
13%11%46%5%245%5%6%34%
2276
16th to endNight
19%16%5%7%5%345%5%6%20%
2340
December1st to 15thNight
19%15%7%11%8%45%44414%
2507
16th to endNight
20%16%8%10%7%2445%5%14%
2688

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%15%7%12%10%5%5%445%10%
1432
16th to endDay
11%18%12%12%10%6%5%5%439%
1536
February1st to 15thDay
13%14%7%10%10%5%6%5%5%5%15%
1619
16th to endDay
11%14%7%10%9%46%6%5%5%18%
1580
March1st to 15thDay
14%10%5%8%6%35%447%28%
1824
16th to endDay
16%9%5%7%6%3445%6%31%
2159
April1st to 15thDay
19%13%45%5%23445%30%
2151
16th to endDay
15%9%26%6%3445%6%34%
2329
May1st to 15thDay
18%8%25%42436%7%34%
2331
16th to endDay
12%5%35%5%345%6%8%41%
2578
June1st to 15thDay
13%6%36%5%25%45%8%39%
2520
16th to endDay
11%426%5%36%5%5%7%39%
2520
July1st to 15thDay
6%425%5%25%5%6%10%45%
2520
16th to endDay
9%425%6%35%5%5%10%42%
2655
August1st to 15thDay
8%5%25%6%36%7%6%9%38%
2370
16th to endDay
12%6%25%5%25%46%7%42%
2393
September1st to 15thDay
13%414435%45%8%42%
2079
16th to endDay
12%6%36%5%35%45%8%39%
1824
October1st to 15thDay
18%8%36%6%34337%35%
1774
16th to endDay
22%12%36%7%34445%24%
1584
November1st to 15thDay
14%10%48%6%24347%34%
1582
16th to endDay
19%18%6%7%6%33345%19%
1620
December1st to 15thDay
16%17%10%12%7%45%33414%
1452
16th to endDay
21%17%10%11%7%34445%10%
1536
January1st to 15thNight
19%16%7%10%7%5%444416%
2506
16th to endNight
11%13%9%11%9%5%6%5%6%6%13%
2688
February1st to 15thNight
12%14%8%9%8%46%445%22%
2231
16th to endNight
15%12%5%9%8%35%45%6%22%
1893
March1st to 15thNight
15%8%5%6%5%35%45%6%34%
2134
16th to endNight
14%8%35%5%35%45%7%36%
2073
April1st to 15thNight
19%9%5%5%5%2435%6%32%
1797
16th to endNight
18%7%3432345%5%40%
1629
May1st to 15thNight
14%5%445%45%45%8%35%
1619
16th to endNight
9%7%35%424449%44%
1534
June1st to 15thNight
11%5%25%42447%8%43%
1440
16th to endNight
9%4244246%6%10%44%
1440
July1st to 15thNight
5%31332445%9%54%
1440
16th to endNight
6%223425%5%5%8%52%
1513
August1st to 15thNight
5%31442446%9%51%
1590
16th to endNight
10%423423447%52%
1807
September1st to 15thNight
11%31332345%6%52%
1869
16th to endNight
11%414325%448%47%
1826
October1st to 15thNight
17%7%2432345%6%41%
1853
16th to endNight
21%9%46%5%24336%31%
2288
November1st to 15thNight
13%10%47%435%45%6%34%
2276
16th to endNight
19%16%5%8%5%345%5%6%20%
2340
December1st to 15thNight
19%14%7%10%8%46%5%35%13%
2507
16th to endNight
20%16%8%10%7%3445%5%14%
2688

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
75%48%9%2
1433
16th to endDay
78%35%8%2
1536
February1st to 15thDay
70%37%14%2
1621
16th to endDay
66%48%13%5%
1580
March1st to 15thDay
55%312%19%8%
1824
16th to endDay
53%312%22%7%1
2160
April1st to 15thDay
54%38%20%12%
2151
16th to endDay
49%312%17%14%2
2329
May1st to 15thDay
48%210%24%11%1
2331
16th to endDay
40%413%27%13%
2582
June1st to 15thDay
43%212%25%15%
2520
16th to endDay
41%414%24%15%1
2520
July1st to 15thDay
33%411%29%18%2
2371
16th to endDay
37%411%26%16%2
2488
August1st to 15thDay
39%5%11%29%12%1
2355
16th to endDay
39%410%26%16%2
2393
September1st to 15thDay
38%410%32%12%1
2079
16th to endDay
42%314%26%13%
1824
October1st to 15thDay
51%29%24%11%
1774
16th to endDay
61%314%15%4
1584
November1st to 15thDay
50%312%23%9%
1582
16th to endDay
67%212%12%4
1620
December1st to 15thDay
74%110%11%2
1452
16th to endDay
76%39%8%2
1536
January1st to 15thNight
70%47%12%4
2506
16th to endNight
68%412%10%3
2688
February1st to 15thNight
64%37%17%6%
2240
16th to endNight
61%311%16%7%
1893
March1st to 15thNight
49%413%20%11%1
2134
16th to endNight
47%213%24%10%1
2073
April1st to 15thNight
52%28%20%15%
1797
16th to endNight
44%311%22%15%3
1629
May1st to 15thNight
46%311%23%12%2
1620
16th to endNight
38%411%27%15%1
1536
June1st to 15thNight
36%414%27%15%1
1440
16th to endNight
34%5%16%25%17%
1440
July1st to 15thNight
25%312%34%20%2
1360
16th to endNight
28%419%28%17%2
1417
August1st to 15thNight
28%414%35%16%
1581
16th to endNight
32%411%29%20%1
1807
September1st to 15thNight
31%310%34%18%1
1869
16th to endNight
35%313%33%12%
1826
October1st to 15thNight
42%210%29%14%
1853
16th to endNight
55%214%19%7%
2288
November1st to 15thNight
49%412%21%11%
2276
16th to endNight
63%313%15%3
2340
December1st to 15thNight
72%310%9%3
2507
16th to endNight
71%211%11%3
2688

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
21%14%34%28%1
90
16th to endDay
30%6%39%17%5%1
96
February1st to 15thDay
17%17%48%13%2
90
16th to endDay
16%20%37%20%4
81
March1st to 15thDay
27%18%25%23%5%
114
16th to endDay
27%7%28%24%10%2
288
April1st to 15thDay
29%8%29%23%8%
270
16th to endDay
21%6%35%22%9%5%
270
May1st to 15thDay
25%12%26%22%7%5%
288
16th to endDay
15%13%32%25%9%4
478
June1st to 15thDay
13%11%32%27%11%3
495
16th to endDay
13%10%34%25%10%5%
495
July1st to 15thDay
9%8%28%26%18%8%
475
16th to endDay
11%6%28%28%16%8%
515
August1st to 15thDay
9%420%27%26%12%
343
16th to endDay
17%5%18%24%21%12%
332
September1st to 15thDay
11%221%26%25%13%
315
16th to endDay
14%5%17%30%22%8%
257
October1st to 15thDay
24%7%23%28%14%1
252
16th to endDay
30%12%34%21%1
96
November1st to 15thDay
11%15%36%25%5%5%
90
16th to endDay
33%12%33%14%6%
90
December1st to 15thDay
25%20%36%14%21
90
16th to endDay
31%26%31%11%
96
January1st to 15thNight
27%14%31%19%6%
900
16th to endNight
18%11%38%25%5%
960
February1st to 15thNight
18%14%37%24%4
733
16th to endNight
23%15%29%27%4
631
March1st to 15thNight
20%12%32%25%9%
720
16th to endNight
17%13%33%26%8%1
729
April1st to 15thNight
24%11%31%26%5%
539
16th to endNight
22%10%32%25%7%1
540
May1st to 15thNight
18%9%32%30%8%
540
16th to endNight
12%7%34%28%15%1
563
June1st to 15thNight
14%7%27%33%15%
540
16th to endNight
9%328%41%14%1
540
July1st to 15thNight
7%219%44%23%2
510
16th to endNight
7%226%38%23%1
564
August1st to 15thNight
6%322%43%21%3
539
16th to endNight
12%319%35%25%3
573
September1st to 15thNight
12%5%22%34%20%5%
609
16th to endNight
13%421%34%21%4
661
October1st to 15thNight
21%6%25%32%13%1
660
16th to endNight
26%12%32%20%7%
704
November1st to 15thNight
20%11%31%27%8%1
700
16th to endNight
27%13%27%24%5%
720
December1st to 15thNight
27%14%33%21%3
887
16th to endNight
28%12%33%21%3
960
Page generated at 2017-09-17 12:05:46. Version ac04

Copyright 2017 A. Danko


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