Hard Labor Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hard Labor Creek Observatory clear sky chart from 2005-11-05 to

2017-09-12
.

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
49%
15547
23%
46878
16%
15503
57%
15503
28%
28799

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
27%
720
23%
2327
10%
716
43%
716
21%
1418
January16th to endNight
27%
768
25%
2472
11%
768
44%
768
22%
1536
February1st to 15thNight
31%
704
26%
2111
11%
700
47%
700
26%
1288
February16th to endNight
28%
631
26%
1893
10%
631
44%
631
25%
1170
March1st to 15thNight
34%
720
25%
2037
13%
720
46%
720
29%
1263
March16th to endNight
39%
768
23%
2112
12%
768
48%
768
32%
1289
April1st to 15thNight
41%
682
25%
1940
16%
682
51%
682
35%
1126
April16th to endNight
49%
540
26%
1680
16%
540
59%
540
32%
972
May1st to 15thNight
50%
540
21%
1620
11%
540
57%
540
30%
989
May16th to endNight
63%
561
22%
1682
15%
561
67%
561
33%
1017
June1st to 15thNight
67%
540
17%
1620
14%
540
68%
540
32%
1009
June16th to endNight
74%
540
17%
1620
15%
540
75%
540
34%
973
July1st to 15thNight
71%
510
13%
1530
11%
510
72%
510
28%
1002
July16th to endNight
76%
564
16%
1595
13%
531
78%
531
29%
1028
August1st to 15thNight
69%
539
18%
1609
17%
536
70%
536
25%
1088
August16th to endNight
65%
584
17%
1916
18%
584
65%
584
22%
1290
September1st to 15thNight
65%
707
19%
1944
17%
707
66%
707
28%
1281
September16th to endNight
57%
657
23%
1815
17%
657
61%
657
29%
1185
October1st to 15thNight
53%
660
31%
1842
24%
660
61%
660
34%
1117
October16th to endNight
54%
704
34%
2112
26%
704
66%
704
38%
1153
November1st to 15thNight
51%
700
32%
2225
26%
700
62%
700
37%
1187
November16th to endNight
42%
720
28%
2340
19%
720
55%
720
30%
1333
December1st to 15thNight
39%
720
24%
2340
15%
720
51%
720
24%
1438
December16th to endNight
33%
768
22%
2496
15%
768
44%
768
20%
1647

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%245%345%5%7%42%
47774
Night
12%42442445%8%46%
47078
TransparencyDay
38%6%11%20%17%5%
47475
Night
36%5%10%19%20%7%
46881
SeeingDay
15%5%17%23%23%13%
5416
Night
14%7%21%29%23%4
15549

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%7%34323346%44%
1611
16th to endDay
18%5%1432245%6%44%
1749
February1st to 15thDay
15%6%24424445%45%
1750
16th to endDay
17%5%2432445%5%45%
1580
March1st to 15thDay
15%4245%23337%45%
1920
16th to endDay
16%5%24424446%45%
2111
April1st to 15thDay
11%435%423447%47%
2017
16th to endDay
9%325%5%2445%7%50%
2280
May1st to 15thDay
10%5%25%5%2435%7%45%
2331
16th to endDay
10%425%5%36%6%6%9%40%
2431
June1st to 15thDay
8%415%6%46%7%7%10%35%
2340
16th to endDay
43145%46%7%8%10%44%
2340
July1st to 15thDay
8%5%26%6%46%7%9%10%31%
2340
16th to endDay
6%426%7%47%7%10%12%30%
2465
August1st to 15thDay
10%5%26%6%5%7%6%8%11%29%
2340
16th to endDay
14%6%26%6%45%6%8%9%28%
2270
September1st to 15thDay
12%5%25%6%46%5%6%7%37%
1936
16th to endDay
17%6%24434346%42%
1815
October1st to 15thDay
14%413323335%54%
1788
16th to endDay
11%313322345%58%
1760
November1st to 15thDay
11%423323435%55%
1632
16th to endDay
14%423423346%49%
1620
December1st to 15thDay
16%8%245%23445%42%
1620
16th to endDay
23%7%24423435%36%
1728
January1st to 15thNight
17%5%24423345%46%
2327
16th to endNight
16%6%24424345%45%
2472
February1st to 15thNight
15%5%14424336%48%
2103
16th to endNight
14%5%245%2433449%
1893
March1st to 15thNight
13%424434445%49%
2037
16th to endNight
12%414324447%50%
2112
April1st to 15thNight
13%413213449%51%
1940
16th to endNight
8%41442445%8%49%
1680
May1st to 15thNight
8%4335%35%45%7%46%
1619
16th to endNight
7%324435%6%6%9%46%
1682
June1st to 15thNight
7%415%5%36%6%6%14%39%
1620
16th to endNight
43235%46%6%8%11%43%
1620
July1st to 15thNight
8%4245%45%6%7%13%36%
1620
16th to endNight
43145%47%8%10%14%35%
1703
August1st to 15thNight
7%425%6%46%6%8%12%34%
1620
16th to endNight
12%5%26%6%45%6%5%10%35%
1916
September1st to 15thNight
9%5%25%5%35%5%6%10%39%
1944
16th to endNight
13%5%16%5%23448%43%
1815
October1st to 15thNight
13%5%23423345%52%
1842
16th to endNight
10%213323335%59%
2112
November1st to 15thNight
11%313212236%59%
2225
16th to endNight
13%423414336%51%
2340
December1st to 15thNight
15%6%24423445%46%
2340
16th to endNight
20%6%25%424446%38%
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%38%15%25%4
1612
16th to endDay
39%46%20%21%7%
1749
February1st to 15thDay
40%37%21%21%5%
1752
16th to endDay
39%37%21%21%6%
1580
March1st to 15thDay
39%38%20%20%7%
1920
16th to endDay
39%411%22%17%4
2112
April1st to 15thDay
37%39%20%22%6%
2017
16th to endDay
33%5%10%20%24%5%
2280
May1st to 15thDay
37%412%22%18%4
2331
16th to endDay
37%8%12%25%13%2
2435
June1st to 15thDay
38%10%18%22%8%1
2340
16th to endDay
29%9%17%24%15%2
2340
July1st to 15thDay
39%11%19%19%7%2
2201
16th to endDay
39%12%17%22%7%1
2310
August1st to 15thDay
45%9%16%19%8%
2327
16th to endDay
48%9%14%15%11%1
2270
September1st to 15thDay
44%7%11%18%16%2
1936
16th to endDay
42%410%20%17%4
1815
October1st to 15thDay
33%310%20%25%7%
1788
16th to endDay
27%36%18%32%11%
1760
November1st to 15thDay
31%36%17%29%11%
1632
16th to endDay
35%46%18%27%8%
1620
December1st to 15thDay
43%37%21%15%8%
1620
16th to endDay
49%37%18%13%7%
1728
January1st to 15thNight
40%37%18%24%6%
2327
16th to endNight
41%3418%21%9%
2472
February1st to 15thNight
38%35%19%22%11%
2112
16th to endNight
38%3420%24%7%
1893
March1st to 15thNight
36%49%18%21%9%
2037
16th to endNight
33%5%10%22%22%6%
2112
April1st to 15thNight
30%49%24%22%8%
1940
16th to endNight
31%5%9%21%22%9%
1680
May1st to 15thNight
35%6%12%20%20%4
1620
16th to endNight
30%8%14%27%14%3
1684
June1st to 15thNight
34%7%19%26%10%1
1620
16th to endNight
30%8%19%23%15%2
1620
July1st to 15thNight
36%10%22%20%7%2
1530
16th to endNight
32%13%24%18%9%2
1595
August1st to 15thNight
39%10%15%22%9%
1609
16th to endNight
42%9%17%18%11%
1916
September1st to 15thNight
37%9%14%17%16%4
1944
16th to endNight
39%5%11%18%18%6%
1815
October1st to 15thNight
33%49%17%26%8%
1842
16th to endNight
29%25%17%30%14%
2112
November1st to 15thNight
28%25%17%29%15%
2225
16th to endNight
34%36%16%27%11%
2340
December1st to 15thNight
39%48%20%18%8%
2340
16th to endNight
46%38%16%18%6%
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
20%12%42%22%21
90
16th to endDay
16%31%35%12%4
96
February1st to 15thDay
20%24%35%20%
90
16th to endDay
29%344%18%3
81
March1st to 15thDay
16%13%29%30%9%
210
16th to endDay
16%9%27%27%18%1
288
April1st to 15thDay
18%8%26%21%20%4
270
16th to endDay
12%5%24%26%25%5%
270
May1st to 15thDay
14%11%29%17%15%13%
288
16th to endDay
14%5%15%22%25%17%
331
June1st to 15thDay
10%111%23%30%23%
315
16th to endDay
7%113%25%26%24%
315
July1st to 15thDay
8%15%24%33%25%
305
16th to endDay
7%1419%36%30%
326
August1st to 15thDay
18%5%23%29%22%
313
16th to endDay
18%16%18%30%23%
332
September1st to 15thDay
15%211%19%33%18%
299
16th to endDay
22%112%27%26%8%
254
October1st to 15thDay
22%120%25%19%10%
255
16th to endDay
12%5%17%28%31%4
272
November1st to 15thDay
27%8%17%27%17%1
140
16th to endDay
13%11%21%34%16%3
90
December1st to 15thDay
28%12%32%17%8%
90
16th to endDay
40%14%22%15%5%1
96
January1st to 15thNight
21%15%27%27%7%
720
16th to endNight
20%15%31%27%4
768
February1st to 15thNight
20%14%27%32%4
704
16th to endNight
17%15%34%29%3
631
March1st to 15thNight
16%12%32%31%7%
720
16th to endNight
14%11%30%29%13%
768
April1st to 15thNight
15%11%29%26%16%
682
16th to endNight
11%7%23%33%22%2
540
May1st to 15thNight
11%326%30%22%4
540
16th to endNight
10%214%31%34%6%
563
June1st to 15thNight
9%210%31%35%9%
540
16th to endNight
5%8%30%43%11%
540
July1st to 15thNight
9%16%24%44%13%
510
16th to endNight
5%6%28%49%10%
564
August1st to 15thNight
10%2426%46%10%
539
16th to endNight
13%16%23%43%10%
584
September1st to 15thNight
12%19%23%43%9%
707
16th to endNight
18%112%31%32%4
657
October1st to 15thNight
16%320%30%24%5%
660
16th to endNight
11%6%20%30%25%3
704
November1st to 15thNight
11%8%23%31%22%2
700
16th to endNight
16%10%25%29%16%1
720
December1st to 15thNight
17%12%24%30%13%1
720
16th to endNight
22%11%26%29%9%
768
Page generated at 2017-09-13 07:39:02. Version ac04

Copyright 2017 A. Danko


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