Sunglow Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sunglow Ranch clear sky chart from 2005-11-05 to 2017-03-25.

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
68%
14867
34%
45202
27%
14826
75%
14826
47%
22545

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
66%
719
31%
2327
31%
716
71%
716
46%
1133
January16th to endNight
60%
768
35%
2496
30%
768
70%
768
40%
1293
February1st to 15thNight
65%
698
35%
2263
31%
696
76%
696
50%
1044
February16th to endNight
54%
632
40%
1763
29%
632
67%
632
48%
927
March1st to 15thNight
57%
720
39%
1980
26%
720
67%
720
53%
994
March16th to endNight
64%
744
38%
2046
23%
744
75%
744
59%
979
April1st to 15thNight
54%
577
38%
1731
22%
577
71%
577
51%
822
April16th to endNight
58%
495
41%
1650
29%
495
77%
495
64%
632
May1st to 15thNight
60%
494
37%
1572
26%
494
74%
494
62%
648
May16th to endNight
68%
513
39%
1540
30%
513
76%
513
64%
645
June1st to 15thNight
78%
495
35%
1485
30%
495
81%
495
65%
639
June16th to endNight
78%
495
24%
1485
21%
495
79%
495
47%
752
July1st to 15thNight
75%
465
16%
1395
14%
465
76%
465
30%
857
July16th to endNight
76%
522
12%
1467
11%
489
76%
489
20%
1015
August1st to 15thNight
75%
494
19%
1486
18%
491
75%
491
27%
946
August16th to endNight
77%
525
21%
1750
24%
525
77%
525
29%
1057
September1st to 15thNight
74%
583
24%
1738
22%
583
75%
583
32%
1084
September16th to endNight
80%
656
37%
1815
27%
656
84%
656
58%
891
October1st to 15thNight
74%
660
37%
1965
28%
660
80%
660
58%
920
October16th to endNight
81%
704
41%
2112
33%
704
87%
704
66%
916
November1st to 15thNight
73%
700
42%
2100
32%
700
81%
700
67%
884
November16th to endNight
64%
720
40%
2200
32%
720
72%
720
50%
1065
December1st to 15thNight
66%
720
36%
2340
34%
720
72%
720
46%
1118
December16th to endNight
58%
768
34%
2496
32%
768
65%
768
40%
1284

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
431332445%7%59%
45739
Night
3313323446%62%
45409
TransparencyDay
24%36%13%26%24%
45434
Night
21%37%14%28%24%
45215
SeeingDay
7%10%22%30%23%5%
4599
Night
4417%35%31%6%
14877

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
441222346%6%60%
1611
16th to endDay
8%5%23313346%56%
1728
February1st to 15thDay
5%412312236%66%
1588
16th to endDay
6%42431324462%
1709
March1st to 15thDay
4312223347%64%
1980
16th to endDay
2312212235%70%
2045
April1st to 15thDay
3311213345%68%
1885
16th to endDay
222112225%77%
1980
May1st to 15thDay
1112112336%73%
2045
16th to endDay
2111112245%75%
2221
June1st to 15thDay
111223236%73%
2145
16th to endDay
2113435%5%6%7%58%
2145
July1st to 15thDay
5%425%7%46%7%8%10%35%
2145
16th to endDay
8%6%37%8%5%8%7%8%10%25%
2285
August1st to 15thDay
7%6%36%7%46%7%8%11%31%
2134
16th to endDay
5%325%6%48%7%9%10%36%
2100
September1st to 15thDay
7%425%5%45%6%7%8%41%
1889
16th to endDay
5%21322345%6%62%
1815
October1st to 15thDay
2113323345%70%
1664
16th to endDay
11221233474%
1760
November1st to 15thDay
112212246%73%
1759
16th to endDay
4313322235%67%
1758
December1st to 15thDay
6%31211435%7%62%
1620
16th to endDay
8%5%13313337%58%
1728
January1st to 15thNight
5%412223345%63%
2327
16th to endNight
6%423423445%58%
2496
February1st to 15thNight
3311213346%66%
2263
16th to endNight
3433323335%63%
1763
March1st to 15thNight
3313313245%66%
1980
16th to endNight
3312212235%72%
2046
April1st to 15thNight
231231334468%
1731
16th to endNight
111111213479%
1650
May1st to 15thNight
112212247%73%
1572
16th to endNight
1122335%78%
1540
June1st to 15thNight
221113235%74%
1485
16th to endNight
12233245%7%6%60%
1485
July1st to 15thNight
2326%6%36%8%9%14%35%
1485
16th to endNight
5%426%7%5%8%10%9%12%26%
1575
August1st to 15thNight
4335%6%47%8%8%11%36%
1495
16th to endNight
4425%5%36%6%8%11%41%
1750
September1st to 15thNight
6%316%5%35%5%7%9%43%
1738
16th to endNight
2212213336%69%
1815
October1st to 15thNight
1112223335%71%
1965
16th to endNight
111212335%76%
2112
November1st to 15thNight
121112246%75%
2100
16th to endNight
4313312235%67%
2200
December1st to 15thNight
6%312224347%62%
2340
16th to endNight
7%5%23312245%59%
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
23%26%13%32%19%
1612
16th to endDay
29%2415%28%19%
1728
February1st to 15thDay
21%1314%30%29%
1588
16th to endDay
26%1313%30%25%
1709
March1st to 15thDay
21%139%35%28%
1980
16th to endDay
17%1311%35%30%
2045
April1st to 15thDay
17%139%37%30%
1885
16th to endDay
13%18%30%44%
1980
May1st to 15thDay
13%2410%26%42%
2045
16th to endDay
13%1310%29%41%
2224
June1st to 15thDay
13%136%23%50%
2145
16th to endDay
22%46%10%22%34%
2145
July1st to 15thDay
38%8%16%15%11%8%
2006
16th to endDay
49%11%17%15%5%
2130
August1st to 15thDay
43%10%15%16%12%2
2119
16th to endDay
39%10%14%15%12%7%
2100
September1st to 15thDay
38%7%11%18%16%7%
1889
16th to endDay
22%26%15%32%19%
1815
October1st to 15thDay
18%25%15%28%29%
1664
16th to endDay
15%1414%31%33%
1760
November1st to 15thDay
13%1416%36%28%
1759
16th to endDay
20%1314%31%28%
1758
December1st to 15thDay
23%15%19%32%17%
1620
16th to endDay
28%26%19%30%12%
1728
January1st to 15thNight
23%26%13%30%23%
2327
16th to endNight
28%1317%29%18%
2496
February1st to 15thNight
19%2415%30%27%
2274
16th to endNight
24%1312%33%24%
1763
March1st to 15thNight
20%1312%32%29%
1980
16th to endNight
16%1310%39%28%
2046
April1st to 15thNight
18%2313%37%24%
1731
16th to endNight
10%210%32%43%
1650
May1st to 15thNight
11%25%8%32%39%
1573
16th to endNight
11%2413%32%36%
1541
June1st to 15thNight
12%135%25%50%
1485
16th to endNight
22%35%9%23%34%
1485
July1st to 15thNight
32%9%21%18%9%7%
1395
16th to endNight
41%13%24%15%41
1467
August1st to 15thNight
34%11%17%18%14%3
1486
16th to endNight
33%9%18%16%14%8%
1750
September1st to 15thNight
33%8%14%19%16%7%
1738
16th to endNight
17%26%18%37%17%
1815
October1st to 15thNight
16%29%16%26%28%
1965
16th to endNight
12%15%14%29%37%
2112
November1st to 15thNight
12%15%18%34%28%
2100
16th to endNight
21%1413%27%32%
2200
December1st to 15thNight
22%26%18%31%18%
2340
16th to endNight
28%17%18%29%14%
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
14%6%28%35%14%
90
16th to endDay
12%7%25%30%17%7%
96
February1st to 15thDay
8%6%16%33%30%3
103
16th to endDay
7%27%30%22%10%1
238
March1st to 15thDay
7%16%31%25%15%3
270
16th to endDay
7%18%30%24%14%3
264
April1st to 15thDay
8%21%37%24%7%1
209
16th to endDay
6%26%34%24%6%1
210
May1st to 15thDay
5%21%39%26%6%
228
16th to endDay
311%35%37%10%1
266
June1st to 15thDay
35%30%39%16%4
255
16th to endDay
5%115%38%35%3
255
July1st to 15thDay
11%8%36%38%4
245
16th to endDay
418%32%38%15%
271
August1st to 15thDay
9%15%27%39%16%
255
16th to endDay
26%30%44%14%
268
September1st to 15thDay
12%10%35%33%6%
255
16th to endDay
7%7%16%30%33%5%
255
October1st to 15thDay
1320%32%28%12%
104
16th to endDay
3415%27%38%11%
96
November1st to 15thDay
314%25%31%21%4
90
16th to endDay
6%20%17%35%18%1
90
December1st to 15thDay
7%423%28%32%3
90
16th to endDay
21%14%18%31%13%
96
January1st to 15thNight
6%219%41%24%5%
720
16th to endNight
8%420%37%24%4
768
February1st to 15thNight
46%18%37%26%5%
704
16th to endNight
48%28%39%15%2
632
March1st to 15thNight
5%8%24%34%22%4
720
16th to endNight
37%21%36%26%4
744
April1st to 15thNight
29%28%42%15%2
577
16th to endNight
17%30%38%17%3
495
May1st to 15thNight
16%27%41%21%1
495
16th to endNight
1421%42%27%2
515
June1st to 15thNight
3113%49%29%2
495
16th to endNight
318%43%41%2
495
July1st to 15thNight
35%29%52%8%
465
16th to endNight
6%321%56%12%
522
August1st to 15thNight
41415%56%18%
494
16th to endNight
6%317%57%14%
525
September1st to 15thNight
6%15%23%50%12%
583
16th to endNight
4110%32%42%8%
656
October1st to 15thNight
2117%37%31%8%
660
16th to endNight
2112%36%36%11%
704
November1st to 15thNight
2218%35%33%8%
700
16th to endNight
6%420%32%28%7%
720
December1st to 15thNight
7%5%17%35%28%4
720
16th to endNight
9%6%18%38%21%5%
768
Page generated at 2017-03-26 10:16:44. Version ac04

Copyright 2017 A. Danko


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