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 2017-12-04.

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%
15724
34%
47799
27%
15683
75%
15683
48%
23833

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
63%
768
39%
2112
23%
768
75%
768
59%
1011
April1st to 15thNight
55%
629
36%
1888
21%
629
71%
629
52%
891
April16th to endNight
58%
540
43%
1800
30%
540
78%
540
65%
683
May1st to 15thNight
60%
539
35%
1715
26%
539
73%
539
61%
709
May16th to endNight
67%
561
41%
1684
31%
561
76%
561
65%
703
June1st to 15thNight
77%
540
34%
1620
28%
540
80%
540
64%
707
June16th to endNight
79%
540
25%
1620
22%
540
79%
540
47%
817
July1st to 15thNight
76%
510
15%
1530
14%
510
76%
510
30%
940
July16th to endNight
76%
564
11%
1593
10%
531
76%
531
20%
1117
August1st to 15thNight
75%
539
17%
1622
17%
536
75%
536
26%
1039
August16th to endNight
78%
573
23%
1910
26%
573
78%
573
30%
1143
September1st to 15thNight
75%
636
24%
1896
22%
636
76%
636
33%
1170
September16th to endNight
80%
716
40%
1980
28%
716
85%
716
61%
955
October1st to 15thNight
75%
720
36%
2144
27%
720
81%
720
60%
988
October16th to endNight
81%
768
42%
2304
35%
768
87%
768
65%
1001
November1st to 15thNight
74%
760
41%
2280
32%
760
81%
760
65%
981
November16th to endNight
65%
780
42%
2384
34%
780
73%
780
51%
1145
December1st to 15thNight
66%
736
36%
2392
33%
736
72%
736
45%
1158
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%60%
48680
Night
3313323446%62%
48006
TransparencyDay
24%36%13%26%25%
48375
Night
21%37%14%28%24%
47812
SeeingDay
6%9%20%30%25%7%
5541
Night
4416%35%32%6%
15734

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
3312212235%71%
2112
April1st to 15thDay
3312213346%68%
2058
16th to endDay
21111112478%
2160
May1st to 15thDay
1112112336%73%
2232
16th to endDay
2111112235%76%
2429
June1st to 15thDay
111223246%72%
2340
16th to endDay
21134345%6%7%59%
2340
July1st to 15thDay
5%425%7%47%7%8%10%36%
2340
16th to endDay
8%6%37%8%5%8%8%8%10%25%
2467
August1st to 15thDay
6%5%36%7%46%6%8%11%32%
2328
16th to endDay
6%325%6%47%7%9%9%38%
2292
September1st to 15thDay
7%4245%45%6%7%8%42%
2061
16th to endDay
421322345%6%64%
1980
October1st to 15thDay
2112323335%71%
1815
16th to endDay
11221234474%
1920
November1st to 15thDay
12221225%7%70%
1909
16th to endDay
4212312235%69%
1904
December1st to 15thDay
6%41212435%7%61%
1649
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
331221223472%
2112
April1st to 15thNight
331231334468%
1888
16th to endNight
111112135%79%
1800
May1st to 15thNight
112212237%74%
1715
16th to endNight
11122235%78%
1684
June1st to 15thNight
221113245%73%
1620
16th to endNight
12233245%6%6%60%
1620
July1st to 15thNight
2426%6%36%8%9%14%36%
1620
16th to endNight
4425%7%5%8%10%10%12%26%
1701
August1st to 15thNight
3335%6%5%7%8%8%11%36%
1631
16th to endNight
4425%436%6%8%11%42%
1910
September1st to 15thNight
6%315%5%35%5%7%9%44%
1896
16th to endNight
2112213336%71%
1980
October1st to 15thNight
1112123335%73%
2144
16th to endNight
11121233477%
2304
November1st to 15thNight
121112246%72%
2280
16th to endNight
4313312335%67%
2384
December1st to 15thNight
6%412224347%61%
2392
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%36%29%
2112
April1st to 15thDay
17%128%38%30%
2058
16th to endDay
12%18%29%45%
2160
May1st to 15thDay
13%239%27%42%
2232
16th to endDay
12%139%29%42%
2432
June1st to 15thDay
14%136%23%49%
2340
16th to endDay
21%46%9%22%35%
2340
July1st to 15thDay
37%9%17%15%11%9%
2201
16th to endDay
49%12%17%14%4
2312
August1st to 15thDay
42%10%15%16%13%2
2313
16th to endDay
38%9%13%15%14%8%
2292
September1st to 15thDay
37%7%11%18%17%8%
2061
16th to endDay
21%26%17%31%20%
1980
October1st to 15thDay
17%25%15%29%29%
1815
16th to endDay
15%1413%32%32%
1920
November1st to 15thDay
13%1418%35%26%
1909
16th to endDay
20%1313%32%28%
1904
December1st to 15thDay
24%15%19%32%17%
1649
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%40%28%
2112
April1st to 15thNight
18%1312%37%25%
1888
16th to endNight
10%210%31%44%
1800
May1st to 15thNight
12%25%8%31%40%
1716
16th to endNight
11%2312%32%37%
1685
June1st to 15thNight
13%135%25%48%
1620
16th to endNight
22%36%9%21%35%
1620
July1st to 15thNight
32%10%20%18%10%8%
1530
16th to endNight
40%15%24%14%31
1593
August1st to 15thNight
35%11%17%17%14%3
1622
16th to endNight
32%9%17%16%14%9%
1910
September1st to 15thNight
32%8%13%18%17%9%
1896
16th to endNight
16%26%18%37%17%
1980
October1st to 15thNight
15%28%15%28%29%
2144
16th to endNight
12%1414%29%36%
2304
November1st to 15thNight
13%15%19%33%26%
2280
16th to endNight
20%1412%29%31%
2384
December1st to 15thNight
23%26%18%30%18%
2392
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%20%29%24%13%4
288
April1st to 15thDay
6%18%33%26%10%3
269
16th to endDay
5%25%32%24%10%2
270
May1st to 15thDay
5%20%36%23%11%2
288
16th to endDay
311%34%38%10%1
330
June1st to 15thDay
35%28%38%16%6%
315
16th to endDay
4113%36%37%6%
315
July1st to 15thDay
8%8%33%42%6%
305
16th to endDay
5%17%28%36%20%
327
August1st to 15thDay
10%426%38%19%
315
16th to endDay
45%27%41%19%
332
September1st to 15thDay
10%9%35%34%8%
315
16th to endDay
6%7%18%32%31%4
315
October1st to 15thDay
1320%30%32%12%
150
16th to endDay
2215%25%42%12%
144
November1st to 15thDay
49%20%35%26%2
135
16th to endDay
5%13%13%34%29%2
135
December1st to 15thDay
8%422%30%33%3
100
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
768
April1st to 15thNight
28%27%42%16%1
629
16th to endNight
17%31%38%17%3
540
May1st to 15thNight
25%27%40%21%2
540
16th to endNight
1322%42%26%1
563
June1st to 15thNight
3113%49%29%2
540
16th to endNight
27%43%41%2
540
July1st to 15thNight
35%30%52%7%
510
16th to endNight
5%320%56%14%
564
August1st to 15thNight
4315%57%18%
539
16th to endNight
6%317%56%15%
573
September1st to 15thNight
7%15%23%51%11%
636
16th to endNight
4110%34%41%7%
716
October1st to 15thNight
2116%36%33%8%
720
16th to endNight
2111%34%38%11%
768
November1st to 15thNight
2216%36%33%7%
760
16th to endNight
6%419%32%29%8%
780
December1st to 15thNight
7%5%17%36%28%4
736
16th to endNight
9%6%18%38%21%5%
768
Page generated at 2017-12-05 08:19:02. Version ac04

Copyright 2017 A. Danko


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