Pine Flat Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pine Flat Observatory clear sky chart from 2005-11-05 to 2017-09-24.

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
67%
15599
31%
46929
27%
15564
71%
15564
45%
24245

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
59%
716
24%
2500
24%
716
65%
716
34%
1351
January16th to endNight
54%
768
28%
2469
26%
768
61%
768
32%
1426
February1st to 15thNight
54%
700
27%
2112
25%
700
58%
700
31%
1266
February16th to endNight
53%
632
24%
1895
24%
632
57%
632
29%
1192
March1st to 15thNight
57%
720
21%
2160
20%
720
61%
720
33%
1279
March16th to endNight
58%
768
21%
1995
15%
768
62%
768
38%
1223
April1st to 15thNight
49%
719
25%
1799
13%
719
54%
719
37%
1125
April16th to endNight
57%
720
28%
1800
15%
720
61%
720
48%
1002
May1st to 15thNight
63%
602
29%
1682
19%
602
66%
602
52%
836
May16th to endNight
55%
534
29%
1658
22%
534
60%
534
44%
804
June1st to 15thNight
72%
360
31%
1440
34%
360
79%
360
52%
554
June16th to endNight
88%
360
41%
1440
48%
360
92%
360
79%
424
July1st to 15thNight
92%
340
34%
1360
42%
340
93%
340
63%
474
July16th to endNight
89%
495
38%
1526
37%
464
90%
464
64%
621
August1st to 15thNight
88%
717
37%
1790
24%
713
88%
713
80%
803
August16th to endNight
92%
764
45%
1910
29%
764
92%
764
80%
865
September1st to 15thNight
90%
720
41%
1806
31%
720
91%
720
74%
849
September16th to endNight
83%
692
46%
1914
39%
692
89%
692
74%
820
October1st to 15thNight
72%
660
35%
1873
32%
660
77%
660
54%
931
October16th to endNight
74%
704
37%
2139
38%
704
78%
704
49%
1065
November1st to 15thNight
71%
700
30%
2275
33%
700
74%
700
43%
1149
November16th to endNight
67%
720
27%
2340
28%
720
70%
720
38%
1237
December1st to 15thNight
57%
720
27%
2358
23%
720
64%
720
33%
1326
December16th to endNight
47%
768
24%
2688
22%
768
54%
768
25%
1623

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
6%412212335%64%
48002
Night
7%5%12212335%63%
47112
TransparencyDay
22%47%19%27%19%
47684
Night
22%47%20%26%17%
46930
SeeingDay
11%15%35%27%7%2
5884
Night
8%5%14%33%30%7%
15610

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
10%412333448%52%
1435
16th to endDay
12%10%24324335%48%
1753
February1st to 15thDay
12%9%23212347%49%
1751
16th to endDay
16%12%33323235%40%
1579
March1st to 15thDay
10%8%33434447%45%
1800
16th to endDay
9%9%24323347%47%
2226
April1st to 15thDay
11%9%24313336%51%
2149
16th to endDay
7%6%2232235%7%57%
2160
May1st to 15thDay
6%312113346%63%
2265
16th to endDay
7%413212346%61%
2453
June1st to 15thDay
3211212245%71%
2520
16th to endDay
11112285%
2520
July1st to 15thDay
211221223476%
2520
16th to endDay
211221222473%
2536
August1st to 15thDay
11111112384%
2160
16th to endDay
111122383%
2292
September1st to 15thDay
1111122480%
2154
16th to endDay
11111122283%
1904
October1st to 15thDay
6%412223235%64%
1755
16th to endDay
6%31342343463%
1731
November1st to 15thDay
6%8%13222245%60%
1584
16th to endDay
8%5%23322446%57%
1620
December1st to 15thDay
9%6%2332335%7%53%
1599
16th to endDay
13%8%33314347%47%
1536
January1st to 15thNight
11%5%22322346%54%
2500
16th to endNight
12%7%23213345%52%
2469
February1st to 15thNight
10%11%34212347%47%
2101
16th to endNight
15%10%33213345%46%
1895
March1st to 15thNight
8%8%32423447%50%
2160
16th to endNight
10%7%1322445%7%50%
1995
April1st to 15thNight
12%7%13313245%53%
1799
16th to endNight
6%5%12213336%64%
1800
May1st to 15thNight
6%22212236%68%
1682
16th to endNight
8%31221113468%
1657
June1st to 15thNight
421212235%73%
1440
16th to endNight
1112387%
1440
July1st to 15thNight
11121223478%
1440
16th to endNight
2112113380%
1631
August1st to 15thNight
111111385%
1800
16th to endNight
11112285%
1910
September1st to 15thNight
121123282%
1806
16th to endNight
111223282%
1914
October1st to 15thNight
6%31221223468%
1873
16th to endNight
441331243366%
2139
November1st to 15thNight
7%5%1331234461%
2275
16th to endNight
6%5%24313347%55%
2340
December1st to 15thNight
10%5%24323446%53%
2358
16th to endNight
14%8%33323346%46%
2688

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
29%5%7%21%24%11%
1435
16th to endDay
38%5%8%15%18%14%
1753
February1st to 15thDay
34%48%21%22%9%
1751
16th to endDay
43%5%6%21%19%2
1579
March1st to 15thDay
35%7%11%19%17%9%
1800
16th to endDay
33%6%14%24%16%4
2226
April1st to 15thDay
34%5%9%26%18%6%
2149
16th to endDay
25%5%13%27%23%4
2160
May1st to 15thDay
21%410%25%32%6%
2265
16th to endDay
23%47%32%28%3
2456
June1st to 15thDay
14%47%21%32%19%
2520
16th to endDay
6%229%40%38%
2520
July1st to 15thDay
11%3410%24%45%
2371
16th to endDay
15%3413%29%33%
2378
August1st to 15thDay
8%129%35%42%
2146
16th to endDay
7%2211%43%33%
2292
September1st to 15thDay
9%25%13%32%36%
2154
16th to endDay
9%1122%38%26%
1904
October1st to 15thDay
21%45%21%28%18%
1755
16th to endDay
21%5%5%17%28%21%
1731
November1st to 15thDay
25%5%7%18%26%16%
1584
16th to endDay
27%5%9%17%25%15%
1620
December1st to 15thDay
29%6%10%20%21%11%
1599
16th to endDay
35%7%9%21%15%10%
1536
January1st to 15thNight
29%5%6%21%23%12%
2500
16th to endNight
33%5%7%17%19%17%
2469
February1st to 15thNight
36%47%18%22%11%
2112
16th to endNight
38%5%8%20%21%5%
1895
March1st to 15thNight
32%6%10%21%19%9%
2160
16th to endNight
31%6%16%24%17%3
1995
April1st to 15thNight
32%410%30%15%6%
1799
16th to endNight
19%6%13%33%22%4
1800
May1st to 15thNight
18%310%31%30%4
1683
16th to endNight
20%38%29%33%3
1658
June1st to 15thNight
14%39%22%33%15%
1440
16th to endNight
41312%42%35%
1440
July1st to 15thNight
9%3412%26%44%
1360
16th to endNight
11%35%14%28%36%
1526
August1st to 15thNight
6%1311%36%39%
1790
16th to endNight
6%1113%44%30%
1910
September1st to 15thNight
8%3313%35%35%
1806
16th to endNight
8%2223%36%26%
1914
October1st to 15thNight
18%3424%30%18%
1873
16th to endNight
20%4420%29%20%
2139
November1st to 15thNight
24%48%17%28%17%
2275
16th to endNight
25%6%9%15%26%16%
2340
December1st to 15thNight
30%6%8%20%22%11%
2358
16th to endNight
37%7%10%18%15%11%
2688

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
33%17%33%7%34
63
16th to endDay
21%14%33%21%8%
261
February1st to 15thDay
16%19%30%22%7%2
266
16th to endDay
26%19%31%17%41
238
March1st to 15thDay
18%22%29%19%7%2
270
16th to endDay
15%24%33%19%5%1
288
April1st to 15thDay
23%27%28%16%31
269
16th to endDay
15%32%27%20%21
270
May1st to 15thDay
15%24%33%18%5%2
288
16th to endDay
17%18%32%23%5%2
330
June1st to 15thDay
6%17%42%25%5%2
315
16th to endDay
215%41%25%9%5%
315
July1st to 15thDay
25%37%40%9%5%
305
16th to endDay
2333%42%10%7%
327
August1st to 15thDay
47%43%29%8%6%
315
16th to endDay
337%42%10%5%
332
September1st to 15thDay
25%46%34%9%1
315
16th to endDay
410%41%32%9%1
288
October1st to 15thDay
7%17%40%29%5%
255
16th to endDay
9%12%35%34%7%
243
November1st to 15thDay
11%8%10%33%30%6%
90
16th to endDay
12%15%21%37%13%
90
December1st to 15thDay
11%14%36%28%8%
87
16th to endDay
14%20%23%29%10%1
64
January1st to 15thNight
13%317%33%24%7%
720
16th to endNight
15%420%33%21%5%
768
February1st to 15thNight
12%7%18%33%20%7%
704
16th to endNight
17%8%16%32%19%4
632
March1st to 15thNight
9%7%20%33%22%6%
720
16th to endNight
11%9%16%37%21%4
768
April1st to 15thNight
12%11%19%31%21%3
719
16th to endNight
6%12%20%33%22%5%
720
May1st to 15thNight
5%7%20%39%23%3
603
16th to endNight
8%13%17%32%25%2
536
June1st to 15thNight
4216%44%28%3
360
16th to endNight
18%52%33%3
360
July1st to 15thNight
1230%56%8%
340
16th to endNight
1223%59%12%
495
August1st to 15thNight
17%33%47%9%
717
16th to endNight
1326%51%16%
764
September1st to 15thNight
5%30%48%14%
720
16th to endNight
1111%28%44%12%
692
October1st to 15thNight
6%213%37%30%9%
660
16th to endNight
6%310%32%34%11%
704
November1st to 15thNight
8%5%9%35%31%9%
700
16th to endNight
9%414%38%27%6%
720
December1st to 15thNight
10%5%19%37%21%4
720
16th to endNight
15%7%22%33%16%3
768
Page generated at 2017-09-25 06:02:29. Version ac04

Copyright 2017 A. Danko


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