Jumbo Rocks
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jumbo Rocks clear sky chart from 2005-11-05 to 2017-05-01.

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
72%
15635
39%
45675
30%
15593
79%
15593
60%
20494

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
64%
720
33%
2327
28%
716
74%
716
44%
1105
January16th to endNight
59%
768
38%
2370
27%
768
74%
768
44%
1166
February1st to 15thNight
63%
699
38%
2109
30%
698
76%
698
52%
979
February16th to endNight
58%
632
36%
1895
33%
632
67%
632
45%
955
March1st to 15thNight
62%
720
35%
2130
29%
720
74%
720
52%
993
March16th to endNight
66%
768
38%
2091
27%
768
75%
768
55%
1012
April1st to 15thNight
56%
719
38%
1799
17%
719
68%
719
58%
897
April16th to endNight
63%
701
43%
1781
19%
701
74%
701
71%
799
May1st to 15thNight
69%
497
45%
1493
30%
497
77%
497
73%
577
May16th to endNight
70%
514
37%
1541
27%
513
75%
513
73%
604
June1st to 15thNight
78%
495
37%
1485
31%
495
80%
495
77%
568
June16th to endNight
82%
495
34%
1485
29%
495
84%
495
78%
577
July1st to 15thNight
86%
465
33%
1395
29%
465
87%
465
65%
601
July16th to endNight
84%
522
35%
1467
30%
489
85%
489
58%
672
August1st to 15thNight
90%
632
39%
1616
27%
629
91%
629
74%
748
August16th to endNight
90%
700
41%
1750
29%
700
90%
700
70%
853
September1st to 15thNight
91%
660
41%
1742
33%
660
93%
660
75%
784
September16th to endNight
86%
656
47%
1815
42%
656
91%
656
82%
727
October1st to 15thNight
75%
660
45%
1815
35%
660
83%
660
71%
794
October16th to endNight
79%
704
45%
2118
41%
704
87%
704
69%
869
November1st to 15thNight
73%
700
39%
2275
35%
700
84%
700
61%
935
November16th to endNight
72%
720
42%
2340
40%
720
80%
720
57%
980
December1st to 15thNight
66%
720
35%
2340
30%
720
76%
720
45%
1098
December16th to endNight
58%
768
36%
2496
29%
768
70%
768
41%
1201

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
1112212235%73%
46079
Night
1112212335%74%
45873
TransparencyDay
13%2313%26%39%
45774
Night
13%2413%28%37%
45679
SeeingDay
413%24%34%18%5%
5251
Night
36%15%30%34%11%
15642

By Month

Percentage Cloud Cover SW (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
2314313346%65%
1611
16th to endDay
3323322346%63%
1851
February1st to 15thDay
2213323336%67%
1751
16th to endDay
121342345%6%62%
1579
March1st to 15thDay
1111113447%70%
1830
16th to endDay
1111212237%72%
2130
April1st to 15thDay
2112213336%70%
2149
16th to endDay
1111235%81%
2178
May1st to 15thDay
111213480%
2138
16th to endDay
111112483%
2221
June1st to 15thDay
1111112483%
2145
16th to endDay
11111111285%
2145
July1st to 15thDay
3111213347%69%
2145
16th to endDay
2113323347%65%
2285
August1st to 15thDay
111212335%75%
2002
16th to endDay
222212335%73%
2100
September1st to 15thDay
111213245%76%
1887
16th to endDay
111122283%
1815
October1st to 15thDay
111121232378%
1815
16th to endDay
11111222479%
1750
November1st to 15thDay
1211212225%75%
1584
16th to endDay
1211213247%71%
1620
December1st to 15thDay
321332436%8%61%
1620
16th to endDay
3323314436%61%
1728
January1st to 15thNight
131332345%6%64%
2327
16th to endNight
321342334465%
2370
February1st to 15thNight
1312213446%68%
2101
16th to endNight
221342446%7%61%
1895
March1st to 15thNight
221121345%6%68%
2130
16th to endNight
112323346%70%
2091
April1st to 15thNight
1212212335%73%
1799
16th to endNight
1112135%82%
1781
May1st to 15thNight
1113484%
1493
16th to endNight
12112484%
1540
June1st to 15thNight
1132286%
1485
16th to endNight
11121188%
1485
July1st to 15thNight
211221233474%
1485
16th to endNight
3212323335%68%
1575
August1st to 15thNight
11112245%78%
1625
16th to endNight
211212335%76%
1750
September1st to 15thNight
111112235%79%
1742
16th to endNight
1111289%
1815
October1st to 15thNight
1111133479%
1815
16th to endNight
1111235%79%
2118
November1st to 15thNight
11121232477%
2275
16th to endNight
2211212335%74%
2340
December1st to 15thNight
3213223446%64%
2340
16th to endNight
3214323346%64%
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
19%25%18%30%23%
1612
16th to endDay
21%3418%29%22%
1851
February1st to 15thDay
18%2416%30%26%
1751
16th to endDay
21%45%17%31%20%
1579
March1st to 15thDay
13%3318%30%31%
1830
16th to endDay
14%2321%33%25%
2130
April1st to 15thDay
16%2412%35%28%
2149
16th to endDay
8%2314%32%39%
2178
May1st to 15thDay
10%128%31%45%
2138
16th to endDay
8%1210%32%45%
2224
June1st to 15thDay
8%118%16%64%
2145
16th to endDay
8%1310%75%
2145
July1st to 15thDay
14%338%19%49%
2006
16th to endDay
17%3417%22%33%
2130
August1st to 15thDay
11%2210%23%49%
1987
16th to endDay
14%3310%25%43%
2100
September1st to 15thDay
11%3210%21%50%
1887
16th to endDay
7%11425%58%
1815
October1st to 15thDay
11%139%30%43%
1815
16th to endDay
10%2410%25%46%
1750
November1st to 15thDay
14%2312%33%34%
1584
16th to endDay
13%2415%30%33%
1620
December1st to 15thDay
20%46%21%24%23%
1620
16th to endDay
23%36%22%25%16%
1728
January1st to 15thNight
20%4316%28%26%
2327
16th to endNight
22%25%17%23%27%
2370
February1st to 15thNight
16%35%15%29%28%
2112
16th to endNight
20%45%17%29%21%
1895
March1st to 15thNight
15%3416%31%27%
2130
16th to endNight
15%35%17%34%24%
2091
April1st to 15thNight
14%25%17%34%27%
1799
16th to endNight
7%1314%34%37%
1781
May1st to 15thNight
6%1114%35%40%
1494
16th to endNight
6%1314%39%35%
1541
June1st to 15thNight
6%1210%19%59%
1485
16th to endNight
7%5%10%75%
1485
July1st to 15thNight
12%228%18%55%
1395
16th to endNight
16%2415%27%33%
1467
August1st to 15thNight
9%2311%24%48%
1616
16th to endNight
11%3110%26%47%
1750
September1st to 15thNight
8%2410%22%51%
1742
16th to endNight
5%116%25%60%
1815
October1st to 15thNight
9%149%33%40%
1815
16th to endNight
8%249%25%49%
2118
November1st to 15thNight
12%2311%34%36%
2275
16th to endNight
14%1315%30%34%
2340
December1st to 15thNight
20%37%15%27%25%
2340
16th to endNight
21%38%20%26%19%
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
11%10%31%40%7%
90
16th to endDay
7%23%24%31%10%3
219
February1st to 15thDay
5%15%35%25%15%2
266
16th to endDay
8%23%30%22%14%
238
March1st to 15thDay
320%24%32%17%2
270
16th to endDay
5%22%27%31%11%2
288
April1st to 15thDay
11%24%26%19%13%4
269
16th to endDay
327%30%24%12%1
270
May1st to 15thDay
5%17%31%32%10%3
229
16th to endDay
116%26%37%10%6%
266
June1st to 15thDay
28%31%34%17%6%
255
16th to endDay
4429%30%20%10%
255
July1st to 15thDay
2116%42%26%11%
245
16th to endDay
219%47%23%15%
271
August1st to 15thDay
1119%41%26%10%
255
16th to endDay
3112%42%26%14%
268
September1st to 15thDay
3220%46%21%5%
255
16th to endDay
37%19%38%25%4
255
October1st to 15thDay
112%26%42%14%1
255
16th to endDay
410%20%29%33%2
166
November1st to 15thDay
114%16%24%35%7%
90
16th to endDay
5%16%28%24%20%4
90
December1st to 15thDay
418%11%34%30%1
90
16th to endDay
9%15%21%37%15%
96
January1st to 15thNight
47%17%35%23%11%
720
16th to endNight
6%8%20%31%25%8%
768
February1st to 15thNight
47%19%33%27%7%
704
16th to endNight
39%24%35%18%8%
632
March1st to 15thNight
39%20%32%25%7%
720
16th to endNight
110%16%35%25%9%
768
April1st to 15thNight
211%24%30%24%6%
719
16th to endNight
9%24%30%25%9%
701
May1st to 15thNight
18%19%32%34%5%
498
16th to endNight
6%20%33%29%7%
515
June1st to 15thNight
1216%41%33%4
495
16th to endNight
1112%33%44%6%
495
July1st to 15thNight
35%28%50%12%
465
16th to endNight
31324%56%10%
522
August1st to 15thNight
2318%59%15%
632
16th to endNight
3216%52%25%
700
September1st to 15thNight
2323%52%18%
660
16th to endNight
118%28%42%18%
656
October1st to 15thNight
2315%32%36%10%
660
16th to endNight
1411%28%38%16%
704
November1st to 15thNight
1417%29%35%12%
700
16th to endNight
46%13%29%32%14%
720
December1st to 15thNight
47%15%35%27%9%
720
16th to endNight
7%11%17%32%23%6%
768
Page generated at 2017-05-02 05:43:34. Version ac04

Copyright 2017 A. Danko


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