A.H. Stephens Memorial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the A.H. Stephens Memorial Park clear sky chart from 2005-11-05 to 2017-09-10.

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
48%
15613
23%
46849
15%
15570
57%
15570
28%
28854

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
28%
720
23%
2327
10%
716
45%
716
21%
1411
January16th to endNight
26%
768
24%
2496
11%
768
42%
768
22%
1543
February1st to 15thNight
32%
704
26%
2120
11%
701
48%
701
26%
1287
February16th to endNight
25%
631
25%
1893
9%
631
42%
631
25%
1153
March1st to 15thNight
32%
720
25%
2010
11%
720
44%
720
28%
1248
March16th to endNight
37%
768
22%
2112
11%
768
46%
768
31%
1289
April1st to 15thNight
39%
718
25%
1976
14%
718
49%
718
34%
1166
April16th to endNight
48%
549
27%
1661
17%
549
57%
549
34%
953
May1st to 15thNight
51%
540
22%
1620
13%
540
58%
540
32%
972
May16th to endNight
61%
561
21%
1682
15%
561
64%
561
31%
1035
June1st to 15thNight
64%
540
16%
1620
13%
540
66%
540
28%
1047
June16th to endNight
73%
540
17%
1620
14%
540
75%
540
33%
992
July1st to 15thNight
68%
510
12%
1530
10%
510
69%
510
25%
1040
July16th to endNight
74%
564
13%
1595
12%
531
76%
531
28%
1035
August1st to 15thNight
69%
539
17%
1609
16%
536
69%
536
23%
1101
August16th to endNight
64%
612
16%
1898
15%
612
65%
612
23%
1277
September1st to 15thNight
64%
700
18%
1925
16%
700
65%
700
27%
1290
September16th to endNight
54%
657
21%
1815
15%
657
59%
657
28%
1194
October1st to 15thNight
53%
660
31%
1864
24%
660
61%
660
35%
1122
October16th to endNight
51%
704
35%
2112
26%
704
64%
704
38%
1151
November1st to 15thNight
52%
700
32%
2188
24%
700
64%
700
38%
1171
November16th to endNight
40%
720
27%
2340
17%
720
55%
720
30%
1330
December1st to 15thNight
40%
720
25%
2340
17%
720
52%
720
24%
1416
December16th to endNight
34%
768
23%
2496
15%
768
45%
768
20%
1631

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%35%5%5%7%42%
47770
Night
11%5%2442445%7%46%
47049
TransparencyDay
39%6%11%20%17%5%
47471
Night
36%5%11%19%19%7%
46852
SeeingDay
15%6%20%23%23%10%
5477
Night
14%8%22%29%21%3
15615

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%24423345%44%
1611
16th to endDay
16%6%2422345%6%46%
1728
February1st to 15thDay
15%5%24424445%46%
1739
16th to endDay
16%5%15%323335%48%
1580
March1st to 15thDay
15%424424446%48%
1948
16th to endDay
15%5%24325%445%46%
2111
April1st to 15thDay
10%425%425%447%48%
1972
16th to endDay
9%3235%35%5%5%7%49%
2307
May1st to 15thDay
11%4245%25%5%5%8%44%
2331
16th to endDay
10%5%25%5%36%6%6%8%40%
2431
June1st to 15thDay
9%426%7%46%7%6%10%35%
2340
16th to endDay
43246%47%6%7%10%40%
2340
July1st to 15thDay
8%5%26%7%5%7%7%7%9%31%
2340
16th to endDay
6%427%7%5%7%8%8%11%28%
2465
August1st to 15thDay
9%5%27%8%5%7%7%7%9%28%
2340
16th to endDay
14%6%36%7%46%6%7%9%28%
2288
September1st to 15thDay
11%5%36%5%35%5%6%7%38%
1923
16th to endDay
17%6%25%434445%40%
1815
October1st to 15thDay
17%413313345%52%
1763
16th to endDay
10%32332323459%
1760
November1st to 15thDay
12%423323246%54%
1670
16th to endDay
13%423423345%50%
1620
December1st to 15thDay
15%6%25%42445%6%42%
1620
16th to endDay
22%7%35%323346%37%
1728
January1st to 15thNight
14%6%24423445%45%
2327
16th to endNight
16%6%3432334447%
2496
February1st to 15thNight
16%424423345%48%
2112
16th to endNight
14%5%24423446%48%
1893
March1st to 15thNight
12%5%24224347%48%
2010
16th to endNight
12%424325%337%50%
2112
April1st to 15thNight
11%413423347%52%
1976
16th to endNight
8%3145%24448%51%
1661
May1st to 15thNight
7%5%24426%45%8%48%
1619
16th to endNight
6%415%5%25%6%6%8%45%
1682
June1st to 15thNight
8%4346%36%5%8%12%36%
1620
16th to endNight
4325%435%7%8%11%43%
1620
July1st to 15thNight
7%435%5%46%7%9%11%33%
1620
16th to endNight
5%415%5%47%7%9%13%35%
1703
August1st to 15thNight
7%5%25%7%5%5%8%8%11%32%
1620
16th to endNight
11%6%25%6%25%6%8%10%33%
1898
September1st to 15thNight
9%5%26%5%346%6%9%39%
1925
16th to endNight
15%5%25%6%24337%43%
1815
October1st to 15thNight
14%41332334453%
1864
16th to endNight
9%314324345%58%
2112
November1st to 15thNight
10%413313236%58%
2188
16th to endNight
13%424423345%51%
2340
December1st to 15thNight
13%7%24423446%46%
2340
16th to endNight
18%7%24424345%41%
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
41%48%15%25%4
1612
16th to endDay
38%36%19%23%8%
1728
February1st to 15thDay
39%37%21%20%6%
1741
16th to endDay
38%35%21%23%7%
1580
March1st to 15thDay
37%47%20%20%8%
1948
16th to endDay
38%411%21%18%5%
2112
April1st to 15thDay
34%49%20%22%7%
1972
16th to endDay
33%5%9%21%23%6%
2307
May1st to 15thDay
36%5%13%21%18%4
2331
16th to endDay
39%6%14%23%13%2
2435
June1st to 15thDay
40%8%17%22%9%1
2340
16th to endDay
33%9%16%22%14%3
2340
July1st to 15thDay
41%11%17%19%7%2
2201
16th to endDay
42%12%17%18%7%2
2310
August1st to 15thDay
47%10%14%18%8%1
2327
16th to endDay
50%9%14%15%9%
2288
September1st to 15thDay
42%7%12%17%17%2
1923
16th to endDay
44%48%20%16%4
1815
October1st to 15thDay
33%39%20%25%7%
1763
16th to endDay
29%2419%30%12%
1760
November1st to 15thDay
32%26%18%26%13%
1670
16th to endDay
35%46%19%25%8%
1620
December1st to 15thDay
41%49%18%16%8%
1620
16th to endDay
48%38%17%14%7%
1728
January1st to 15thNight
39%37%17%24%7%
2327
16th to endNight
41%3417%22%10%
2496
February1st to 15thNight
38%26%19%21%11%
2121
16th to endNight
37%45%19%24%8%
1893
March1st to 15thNight
36%49%18%22%9%
2010
16th to endNight
35%311%20%21%7%
2112
April1st to 15thNight
32%38%24%22%9%
1976
16th to endNight
30%5%10%21%21%10%
1661
May1st to 15thNight
33%5%13%22%19%5%
1620
16th to endNight
33%8%15%25%14%3
1684
June1st to 15thNight
37%8%19%22%10%1
1620
16th to endNight
29%11%18%23%13%3
1620
July1st to 15thNight
37%13%19%19%6%3
1530
16th to endNight
33%12%24%18%7%2
1595
August1st to 15thNight
41%11%15%21%8%1
1609
16th to endNight
41%10%19%17%10%
1898
September1st to 15thNight
37%10%14%15%16%4
1925
16th to endNight
41%5%11%17%18%5%
1815
October1st to 15thNight
33%47%19%25%9%
1864
16th to endNight
28%35%18%30%14%
2112
November1st to 15thNight
28%36%17%28%16%
2188
16th to endNight
34%27%15%26%12%
2340
December1st to 15thNight
38%48%20%18%8%
2340
16th to endNight
45%38%18%17%7%
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%16%43%13%7%
90
16th to endDay
17%32%34%10%5%
96
February1st to 15thDay
20%24%40%15%
90
16th to endDay
19%9%50%16%3
81
March1st to 15thDay
15%15%30%29%7%1
238
16th to endDay
15%11%31%25%14%1
288
April1st to 15thDay
15%14%27%20%18%4
270
16th to endDay
11%6%24%29%24%4
270
May1st to 15thDay
14%7%32%18%16%10%
288
16th to endDay
14%417%21%27%13%
331
June1st to 15thDay
10%213%22%31%19%
315
16th to endDay
7%14%28%26%23%
315
July1st to 15thDay
8%10%22%35%21%
305
16th to endDay
9%5%24%39%20%
326
August1st to 15thDay
16%112%24%27%16%
313
16th to endDay
15%11%22%30%18%
332
September1st to 15thDay
13%213%21%35%13%
294
16th to endDay
22%315%29%21%7%
254
October1st to 15thDay
24%219%26%18%7%
255
16th to endDay
12%5%19%27%25%9%
272
November1st to 15thDay
24%6%23%22%19%3
178
16th to endDay
8%11%27%31%17%3
90
December1st to 15thDay
20%16%32%24%6%
90
16th to endDay
37%13%22%17%6%2
96
January1st to 15thNight
19%17%28%25%8%
720
16th to endNight
19%16%34%25%4
768
February1st to 15thNight
19%14%28%31%4
704
16th to endNight
16%18%35%26%3
631
March1st to 15thNight
15%15%32%30%6%
720
16th to endNight
15%12%30%27%13%
768
April1st to 15thNight
14%13%30%27%14%
718
16th to endNight
12%6%26%35%16%1
549
May1st to 15thNight
10%5%26%32%21%3
540
16th to endNight
10%317%31%33%4
563
June1st to 15thNight
10%213%33%31%7%
540
16th to endNight
5%111%34%36%9%
540
July1st to 15thNight
9%10%29%37%12%
510
16th to endNight
6%7%30%46%7%
564
August1st to 15thNight
11%5%30%44%7%
539
16th to endNight
14%17%29%38%8%
612
September1st to 15thNight
12%210%28%39%7%
700
16th to endNight
19%115%31%27%3
657
October1st to 15thNight
16%321%27%26%4
660
16th to endNight
11%7%24%30%23%3
704
November1st to 15thNight
12%6%24%31%21%3
700
16th to endNight
13%12%29%26%16%1
720
December1st to 15thNight
18%11%24%30%12%1
720
16th to endNight
21%13%26%28%8%
768
Page generated at 2017-09-11 19:35:20. Version ac04

Copyright 2017 A. Danko


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