Bill Sadowski Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bill Sadowski Park clear sky chart from 2005-11-05 to 2017-04-26.

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
56%
15803
16%
45576
13%
15765
61%
15765
23%
30491

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
47%
716
15%
2327
12%
716
53%
716
20%
1496
January16th to endNight
49%
768
23%
2463
19%
768
58%
768
25%
1479
February1st to 15thNight
51%
701
25%
2084
20%
699
57%
699
30%
1243
February16th to endNight
54%
631
30%
1735
17%
631
64%
631
35%
1006
March1st to 15thNight
50%
720
23%
1980
15%
720
57%
720
28%
1238
March16th to endNight
55%
768
23%
2112
18%
768
60%
768
31%
1266
April1st to 15thNight
64%
718
23%
1976
17%
718
69%
718
38%
1112
April16th to endNight
58%
704
22%
1766
12%
704
64%
704
32%
1101
May1st to 15thNight
63%
659
24%
1649
15%
659
66%
659
38%
955
May16th to endNight
58%
578
10%
1604
9%
578
59%
578
22%
1146
June1st to 15thNight
53%
495
8%
1485
6%
495
53%
495
14%
1135
June16th to endNight
65%
495
5%
1485
4%
495
65%
495
17%
1085
July1st to 15thNight
65%
465
5%
1395
5%
465
65%
465
16%
1050
July16th to endNight
66%
522
9%
1469
8%
489
71%
489
24%
971
August1st to 15thNight
68%
574
8%
1554
7%
571
68%
571
21%
1105
August16th to endNight
64%
700
5%
1857
4%
700
65%
700
19%
1392
September1st to 15thNight
62%
660
4%
1815
4%
660
62%
660
13%
1461
September16th to endNight
53%
657
4%
1815
2%
657
55%
657
11%
1474
October1st to 15thNight
59%
660
11%
1919
12%
660
60%
660
16%
1426
October16th to endNight
50%
704
16%
2112
14%
704
54%
704
19%
1494
November1st to 15thNight
51%
700
20%
2101
16%
700
56%
700
22%
1414
November16th to endNight
50%
720
21%
2160
16%
720
57%
720
19%
1463
December1st to 15thNight
51%
720
20%
2217
16%
720
57%
720
20%
1490
December16th to endNight
59%
768
21%
2496
20%
768
64%
768
26%
1489

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
8%5%36%7%47%7%8%10%29%
46064
Night
6%425%6%36%6%7%10%39%
45782
TransparencyDay
40%13%17%15%9%2
45766
Night
38%10%17%19%11%2
45584
SeeingDay
8%10%8%21%27%22%
5536
Night
7%15%9%24%27%14%
15813

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
8%6%36%6%45%6%7%9%33%
1611
16th to endDay
8%435%6%46%6%7%10%36%
1758
February1st to 15thDay
9%425%6%345%6%9%42%
1769
16th to endDay
6%3135%35%6%7%10%44%
1738
March1st to 15thDay
6%4246%36%6%8%11%39%
1980
16th to endDay
5%445%5%45%5%7%10%40%
2111
April1st to 15thDay
5%3245%35%6%8%12%43%
1972
16th to endDay
6%4145%46%7%8%12%37%
2105
May1st to 15thDay
43145%47%7%8%11%40%
1972
16th to endDay
9%6%37%9%5%8%8%10%11%20%
2165
June1st to 15thDay
11%7%410%9%6%10%8%6%9%14%
2145
16th to endDay
7%6%48%11%6%11%8%9%11%14%
2145
July1st to 15thDay
7%5%47%9%6%8%9%9%13%18%
2145
16th to endDay
6%5%27%9%6%8%9%9%12%21%
2283
August1st to 15thDay
5%6%39%9%6%8%9%9%11%20%
2052
16th to endDay
9%6%37%8%5%9%9%10%10%17%
1989
September1st to 15thDay
8%6%39%10%7%10%9%9%8%15%
1815
16th to endDay
11%9%5%9%10%6%9%8%7%8%13%
1815
October1st to 15thDay
8%6%39%8%5%8%7%8%9%22%
1709
16th to endDay
13%6%37%7%36%6%7%8%29%
1760
November1st to 15thDay
8%5%36%5%46%6%7%9%35%
1757
16th to endDay
9%5%26%6%37%6%7%9%35%
1800
December1st to 15thDay
9%6%35%6%37%5%7%9%33%
1740
16th to endDay
6%5%25%6%36%7%10%11%33%
1728
January1st to 15thNight
7%5%25%6%36%6%8%10%36%
2327
16th to endNight
5%424435%46%11%46%
2463
February1st to 15thNight
9%33442346%9%47%
2082
16th to endNight
421442446%10%53%
1735
March1st to 15thNight
5%315%5%35%5%6%8%48%
1980
16th to endNight
4314425%5%6%9%49%
2112
April1st to 15thNight
32134245%6%10%56%
1976
16th to endNight
6%3244246%8%10%47%
1766
May1st to 15thNight
311442347%10%56%
1649
16th to endNight
8%5%36%6%37%6%8%10%32%
1603
June1st to 15thNight
11%7%36%7%5%7%7%8%11%23%
1485
16th to endNight
5%4246%5%8%8%10%14%28%
1485
July1st to 15thNight
5%436%6%48%8%10%12%28%
1485
16th to endNight
2415%5%46%7%9%13%38%
1577
August1st to 15thNight
5%325%6%47%6%8%14%34%
1565
16th to endNight
6%427%7%5%8%8%10%12%27%
1857
September1st to 15thNight
6%5%38%8%5%9%9%9%10%24%
1815
16th to endNight
7%7%39%9%47%9%8%11%21%
1815
October1st to 15thNight
7%6%26%8%47%6%9%11%28%
1919
16th to endNight
13%6%37%6%36%5%6%7%33%
2112
November1st to 15thNight
8%426%5%36%6%6%8%41%
2101
16th to endNight
9%5%26%6%36%6%6%9%39%
2160
December1st to 15thNight
10%5%25%5%45%6%7%10%37%
2217
16th to endNight
6%3245%36%5%7%10%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
40%11%15%17%11%3
1612
16th to endDay
36%8%16%17%15%4
1758
February1st to 15thDay
34%5%14%22%18%4
1772
16th to endDay
26%9%17%27%14%4
1738
March1st to 15thDay
29%10%18%22%16%2
1980
16th to endDay
30%10%17%23%14%4
2112
April1st to 15thDay
25%9%21%25%16%1
1972
16th to endDay
30%10%17%20%17%2
2105
May1st to 15thDay
27%12%18%24%13%4
1972
16th to endDay
46%15%18%16%4
2169
June1st to 15thDay
56%16%14%9%2
2145
16th to endDay
52%19%18%7%1
2145
July1st to 15thDay
47%19%25%7%
2006
16th to endDay
41%20%27%10%
2128
August1st to 15thDay
43%21%23%10%1
2039
16th to endDay
47%22%21%8%
1989
September1st to 15thDay
52%24%16%6%
1815
16th to endDay
55%21%13%7%2
1815
October1st to 15thDay
47%15%16%13%6%
1709
16th to endDay
46%9%14%13%11%4
1760
November1st to 15thDay
41%8%15%14%15%4
1757
16th to endDay
41%8%12%13%19%5%
1800
December1st to 15thDay
41%9%14%17%15%2
1740
16th to endDay
37%10%15%20%14%2
1728
January1st to 15thNight
40%8%17%20%10%3
2327
16th to endNight
32%9%13%24%15%3
2463
February1st to 15thNight
34%5%12%24%17%6%
2090
16th to endNight
26%7%15%26%18%5%
1735
March1st to 15thNight
33%7%11%25%17%4
1980
16th to endNight
29%8%16%24%17%3
2112
April1st to 15thNight
24%6%18%31%16%2
1976
16th to endNight
29%8%18%22%18%3
1766
May1st to 15thNight
23%7%17%33%14%3
1650
16th to endNight
44%9%18%20%6%
1605
June1st to 15thNight
50%12%21%11%3
1485
16th to endNight
40%17%30%9%
1485
July1st to 15thNight
42%19%27%9%
1395
16th to endNight
32%16%33%15%1
1469
August1st to 15thNight
35%18%29%15%
1554
16th to endNight
43%16%28%10%
1857
September1st to 15thNight
48%21%20%8%1
1815
16th to endNight
54%16%17%8%3
1815
October1st to 15thNight
47%13%16%13%7%1
1919
16th to endNight
48%7%11%18%11%3
2112
November1st to 15thNight
43%7%12%16%17%3
2101
16th to endNight
43%8%10%16%15%5%
2160
December1st to 15thNight
42%8%13%18%13%2
2217
16th to endNight
33%8%14%24%16%2
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
16%325%35%18%
90
16th to endDay
11%9%25%34%15%4
96
February1st to 15thDay
7%7%17%40%24%3
111
16th to endDay
8%11%17%35%25%
239
March1st to 15thDay
6%11%20%38%21%1
270
16th to endDay
6%13%20%32%21%5%
288
April1st to 15thDay
5%12%12%32%31%5%
270
16th to endDay
6%12%5%39%32%2
254
May1st to 15thDay
314%424%37%16%
228
16th to endDay
411%211%38%29%
267
June1st to 15thDay
12%12%5%10%29%29%
255
16th to endDay
6%12%1323%52%
255
July1st to 15thDay
38%422%59%
245
16th to endDay
412%16%27%47%
270
August1st to 15thDay
9%6%7%23%52%
253
16th to endDay
13%5%18%21%49%
268
September1st to 15thDay
7%5%311%22%49%
255
16th to endDay
16%6%7%24%44%
254
October1st to 15thDay
10%6%322%41%16%
255
16th to endDay
18%8%9%26%28%8%
272
November1st to 15thDay
10%10%13%26%28%10%
265
16th to endDay
10%12%21%30%22%2
270
December1st to 15thDay
15%10%12%30%25%6%
210
16th to endDay
429%36%46%1
96
January1st to 15thNight
9%20%14%28%24%3
720
16th to endNight
7%20%16%35%19%
768
February1st to 15thNight
7%17%17%33%23%
704
16th to endNight
5%17%17%38%20%
631
March1st to 15thNight
6%19%18%32%21%2
720
16th to endNight
5%17%15%35%23%2
768
April1st to 15thNight
316%9%39%28%2
718
16th to endNight
6%18%9%38%25%1
704
May1st to 15thNight
318%6%30%35%4
660
16th to endNight
7%19%316%39%13%
580
June1st to 15thNight
8%18%313%33%23%
495
16th to endNight
418%16%30%39%
495
July1st to 15thNight
5%12%16%28%44%
465
16th to endNight
418%5%25%46%
522
August1st to 15thNight
6%10%15%36%40%
574
16th to endNight
8%9%48%32%36%
700
September1st to 15thNight
8%9%210%31%38%
660
16th to endNight
10%9%5%11%26%36%
657
October1st to 15thNight
10%10%421%36%15%
660
16th to endNight
16%10%10%23%27%11%
704
November1st to 15thNight
9%15%14%29%24%5%
700
16th to endNight
10%17%12%31%23%4
720
December1st to 15thNight
11%17%12%30%25%2
720
16th to endNight
5%17%12%27%31%5%
768
Page generated at 2017-04-27 17:49:02. Version ac04

Copyright 2017 A. Danko


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