Highland Road Park Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Highland Road Park Observatory clear sky chart from 2005-11-05 to 2017-08-12.

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
57%
15145
23%
46434
19%
15101
62%
15101
31%
27814

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
39%
900
23%
2327
10%
895
48%
895
30%
1504
January16th to endNight
36%
921
25%
2457
11%
921
44%
921
29%
1606
February1st to 15thNight
40%
704
27%
2111
13%
701
50%
701
30%
1284
February16th to endNight
35%
631
22%
1893
11%
631
42%
631
27%
1192
March1st to 15thNight
42%
549
25%
1989
19%
549
52%
549
24%
1179
March16th to endNight
50%
576
24%
2078
20%
576
58%
576
31%
1121
April1st to 15thNight
49%
539
25%
1797
20%
539
60%
539
32%
1016
April16th to endNight
53%
540
26%
1800
24%
540
61%
540
34%
1002
May1st to 15thNight
59%
539
21%
1799
21%
539
65%
539
34%
1005
May16th to endNight
73%
561
23%
1870
25%
561
75%
561
37%
1012
June1st to 15thNight
81%
540
15%
1669
16%
540
82%
540
34%
1000
June16th to endNight
74%
540
15%
1620
16%
540
74%
540
29%
1026
July1st to 15thNight
81%
510
14%
1530
17%
510
82%
510
34%
925
July16th to endNight
79%
564
10%
1658
12%
531
78%
531
26%
1075
August1st to 15thNight
83%
527
14%
1750
18%
524
83%
524
32%
1034
August16th to endNight
74%
525
12%
1750
16%
525
74%
525
23%
1159
September1st to 15thNight
73%
495
21%
1650
24%
495
73%
495
28%
1009
September16th to endNight
72%
592
27%
1750
25%
592
72%
592
32%
1077
October1st to 15thNight
73%
660
32%
1980
28%
660
75%
660
48%
1002
October16th to endNight
62%
704
34%
2112
29%
704
66%
704
40%
1146
November1st to 15thNight
58%
700
32%
2100
27%
700
63%
700
37%
1193
November16th to endNight
53%
720
34%
2160
25%
720
62%
720
37%
1203
December1st to 15thNight
45%
720
26%
2160
19%
720
52%
720
28%
1359
December16th to endNight
36%
888
19%
2424
12%
888
40%
888
23%
1685

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
11%5%36%6%36%5%5%7%37%
47514
Night
10%42442445%8%47%
46640
TransparencyDay
44%6%10%16%15%5%
47223
Night
34%6%13%19%17%8%
46437
SeeingDay
12%312%21%28%22%
5211
Night
12%418%31%26%6%
15148

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
15%6%24433446%42%
1611
16th to endDay
19%7%25%42433343%
1764
February1st to 15thDay
14%6%25%424347%43%
1750
16th to endDay
19%6%25%424435%40%
1580
March1st to 15thDay
17%5%36%5%24446%40%
1980
16th to endDay
10%7%36%5%35%447%42%
2143
April1st to 15thDay
12%5%25%5%3446%8%40%
2151
16th to endDay
11%5%35%5%36%5%5%9%38%
2160
May1st to 15thDay
10%6%25%5%36%5%5%8%37%
2151
16th to endDay
8%5%26%7%5%7%6%6%7%36%
2244
June1st to 15thDay
7%437%8%5%9%8%8%8%27%
2286
16th to endDay
6%5%38%8%6%9%9%8%9%23%
2340
July1st to 15thDay
8%6%37%8%5%9%8%5%9%26%
2340
16th to endDay
8%7%49%8%5%9%7%7%8%23%
2394
August1st to 15thDay
9%6%38%8%48%6%8%10%25%
2112
16th to endDay
12%6%36%8%48%7%8%8%26%
2100
September1st to 15thDay
13%5%27%5%46%5%7%8%32%
1980
16th to endDay
9%6%36%6%35%5%6%6%39%
1863
October1st to 15thDay
7%315%42346%6%53%
1650
16th to endDay
9%313324446%55%
1760
November1st to 15thDay
8%425%4245%47%50%
1758
16th to endDay
11%414424435%52%
1800
December1st to 15thDay
18%6%35%5%34345%39%
1800
16th to endDay
19%8%36%6%25%445%32%
1797
January1st to 15thNight
14%5%2442445%6%45%
2327
16th to endNight
17%6%34413446%44%
2457
February1st to 15thNight
14%5%33414347%46%
2103
16th to endNight
18%5%24323445%45%
1893
March1st to 15thNight
14%6%25%424447%44%
1989
16th to endNight
11%42432335%7%51%
2078
April1st to 15thNight
10%5%145%2345%8%49%
1797
16th to endNight
8%42442345%7%51%
1800
May1st to 15thNight
8%3244245%7%9%47%
1799
16th to endNight
6%2145%2445%9%53%
1869
June1st to 15thNight
3324437%6%8%10%45%
1669
16th to endNight
4326%6%36%7%6%12%38%
1620
July1st to 15thNight
3424336%7%7%14%43%
1620
16th to endNight
5%425%6%36%7%10%13%35%
1771
August1st to 15thNight
5%213435%6%9%12%45%
1762
16th to endNight
6%425%6%45%7%8%11%35%
1750
September1st to 15thNight
8%425%6%345%7%10%41%
1650
16th to endNight
6%4245%35%5%6%9%44%
1750
October1st to 15thNight
4313313347%62%
1980
16th to endNight
9%313413345%59%
2112
November1st to 15thNight
9%423414435%55%
2100
16th to endNight
9%423413336%56%
2160
December1st to 15thNight
15%5%25%5%23347%44%
2160
16th to endNight
18%8%36%42435%6%36%
2424

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
42%46%14%22%9%
1612
16th to endDay
45%35%14%20%10%
1764
February1st to 15thDay
41%47%14%21%9%
1752
16th to endDay
46%35%16%20%7%
1580
March1st to 15thDay
46%47%19%16%6%
1980
16th to endDay
41%47%18%22%5%
2145
April1st to 15thDay
40%5%9%17%18%8%
2151
16th to endDay
40%5%10%21%17%5%
2160
May1st to 15thDay
42%6%11%18%14%7%
2151
16th to endDay
43%6%11%20%16%
2248
June1st to 15thDay
49%9%11%17%11%
2286
16th to endDay
50%10%16%16%6%
2340
July1st to 15thDay
49%10%17%15%5%
2201
16th to endDay
54%10%17%14%3
2245
August1st to 15thDay
49%10%18%14%5%
2100
16th to endDay
52%10%17%9%7%1
2100
September1st to 15thDay
46%7%17%16%10%2
1980
16th to endDay
42%5%10%17%17%5%
1863
October1st to 15thDay
30%310%17%22%15%
1650
16th to endDay
29%3414%30%18%
1760
November1st to 15thDay
33%47%20%26%8%
1758
16th to endDay
34%45%14%26%15%
1800
December1st to 15thDay
46%38%18%15%6%
1800
16th to endDay
52%36%16%15%4
1797
January1st to 15thNight
38%47%15%22%11%
2327
16th to endNight
40%36%15%21%11%
2457
February1st to 15thNight
37%27%18%21%11%
2112
16th to endNight
40%46%17%18%12%
1893
March1st to 15thNight
39%410%18%19%7%
1989
16th to endNight
31%411%21%21%8%
2078
April1st to 15thNight
33%412%20%18%11%
1797
16th to endNight
30%5%12%22%20%8%
1800
May1st to 15thNight
30%6%14%23%17%7%
1800
16th to endNight
27%6%16%28%18%2
1871
June1st to 15thNight
28%10%17%26%15%1
1669
16th to endNight
34%10%22%22%10%
1620
July1st to 15thNight
27%11%31%21%6%
1530
16th to endNight
32%15%29%18%3
1658
August1st to 15thNight
25%14%30%22%6%
1750
16th to endNight
36%13%25%12%7%3
1750
September1st to 15thNight
35%7%20%22%9%4
1650
16th to endNight
34%7%13%19%18%7%
1750
October1st to 15thNight
21%39%20%26%16%
1980
16th to endNight
28%3415%25%22%
2112
November1st to 15thNight
31%38%18%27%11%
2100
16th to endNight
30%36%16%23%19%
2160
December1st to 15thNight
40%39%21%17%6%
2160
16th to endNight
49%38%16%15%7%
2424

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
24%10%32%25%6%1
90
16th to endDay
17%12%41%17%10%
96
February1st to 15thDay
13%13%24%33%13%2
90
16th to endDay
14%7%32%32%13%
81
March1st to 15thDay
28%8%36%20%5%
90
16th to endDay
15%6%24%26%23%3
129
April1st to 15thDay
15%7%25%29%20%1
270
16th to endDay
12%416%38%21%5%
270
May1st to 15thDay
12%316%34%25%7%
288
16th to endDay
9%114%25%30%19%
331
June1st to 15thDay
8%1326%37%23%
441
16th to endDay
10%15%21%32%28%
495
July1st to 15thDay
8%416%33%36%
475
16th to endDay
7%310%37%41%
443
August1st to 15thDay
12%26%30%47%
297
16th to endDay
12%1210%29%44%
268
September1st to 15thDay
11%15%9%34%36%
255
16th to endDay
8%6%21%43%20%
250
October1st to 15thDay
214%31%37%14%
90
16th to endDay
16%215%27%18%19%
96
November1st to 15thDay
18%217%34%18%7%
90
16th to endDay
14%10%28%23%16%6%
90
December1st to 15thDay
26%6%25%25%11%4
90
16th to endDay
26%11%27%25%10%
96
January1st to 15thNight
17%7%30%35%9%
900
16th to endNight
19%8%30%31%9%
921
February1st to 15thNight
16%8%30%35%9%
704
16th to endNight
20%8%32%32%6%
631
March1st to 15thNight
16%6%28%37%11%
549
16th to endNight
12%6%26%38%16%
576
April1st to 15thNight
12%7%25%38%15%
539
16th to endNight
10%326%41%16%1
540
May1st to 15thNight
8%221%45%21%
540
16th to endNight
7%9%42%35%4
563
June1st to 15thNight
3331%51%9%
540
16th to endNight
41324%47%19%
540
July1st to 15thNight
3115%50%28%
510
16th to endNight
5%1210%50%29%
564
August1st to 15thNight
5%113%50%28%
527
16th to endNight
8%1215%46%25%
525
September1st to 15thNight
10%1317%47%20%
495
16th to endNight
8%6%29%46%9%
592
October1st to 15thNight
7%110%37%38%4
660
16th to endNight
12%317%34%29%3
704
November1st to 15thNight
10%319%40%23%2
700
16th to endNight
12%5%23%38%18%1
720
December1st to 15thNight
16%7%24%34%16%
720
16th to endNight
23%7%25%30%11%
888
Page generated at 2017-08-13 13:16:36. Version ac04

Copyright 2017 A. Danko


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