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Feef Peak Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Feef Peak Observatory clear sky chart from 2005-11-05 to 2018-02-13.

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
60%
16332
31%
48803
22%
16291
69%
16291
46%
25016

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
61%
804
33%
2549
27%
803
71%
803
52%
1173
January16th to endNight
56%
832
36%
2704
27%
832
70%
832
52%
1218
February1st to 15thNight
53%
750
29%
2367
21%
748
63%
748
46%
1144
February16th to endNight
42%
632
38%
1894
19%
632
61%
632
48%
921
March1st to 15thNight
51%
720
34%
2036
20%
720
62%
720
46%
1079
March16th to endNight
51%
720
35%
2064
19%
720
64%
720
51%
1013
April1st to 15thNight
43%
539
33%
1798
17%
539
63%
539
42%
858
April16th to endNight
42%
540
35%
1800
20%
540
65%
540
44%
835
May1st to 15thNight
48%
539
25%
1799
18%
539
61%
539
41%
894
May16th to endNight
55%
563
31%
1553
16%
561
70%
561
48%
820
June1st to 15thNight
62%
540
25%
1440
16%
540
69%
540
48%
777
June16th to endNight
71%
540
25%
1440
20%
540
74%
540
50%
774
July1st to 15thNight
73%
510
17%
1437
15%
510
74%
510
32%
896
July16th to endNight
76%
564
16%
1593
16%
531
77%
531
31%
976
August1st to 15thNight
78%
539
15%
1712
16%
536
78%
536
31%
1031
August16th to endNight
77%
573
23%
1910
26%
573
80%
573
32%
1107
September1st to 15thNight
73%
540
23%
1800
24%
540
76%
540
30%
1068
September16th to endNight
68%
564
35%
1932
31%
564
76%
564
43%
948
October1st to 15thNight
64%
720
34%
2160
24%
720
71%
720
51%
1062
October16th to endNight
66%
768
40%
2304
27%
768
74%
768
56%
1078
November1st to 15thNight
65%
845
38%
2365
24%
845
73%
845
62%
1092
November16th to endNight
62%
975
40%
2535
25%
975
69%
975
57%
1304
December1st to 15thNight
56%
975
33%
2699
20%
975
65%
975
50%
1381
December16th to endNight
51%
1040
32%
2912
21%
1040
61%
1040
46%
1567

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
221332345%8%61%
49227
Night
331332345%7%61%
48997
TransparencyDay
20%5%10%22%26%14%
48920
Night
20%5%10%22%26%13%
48805
SeeingDay
5%10%25%31%21%5%
5999
Night
46%25%41%20%1
16338

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
1212223447%67%
1730
16th to endDay
3322222236%68%
1872
February1st to 15thDay
23432235%6%65%
1756
16th to endDay
131332335%9%63%
1580
March1st to 15thDay
231322345%8%62%
1923
16th to endDay
2213223447%65%
2159
April1st to 15thDay
221332345%8%62%
2150
16th to endDay
2313223345%67%
2160
May1st to 15thDay
221232345%8%63%
2151
16th to endDay
2212213447%67%
2554
June1st to 15thDay
11221346%8%66%
2520
16th to endDay
11131345%8%67%
2520
July1st to 15thDay
34236%36%6%8%11%44%
2432
16th to endDay
33245%45%8%8%10%41%
2467
August1st to 15thDay
2313435%6%8%10%48%
2238
16th to endDay
3413435%6%7%10%48%
2292
September1st to 15thDay
6%413435%5%7%9%48%
2160
16th to endDay
222324446%65%
2025
October1st to 15thDay
4212212345%68%
1800
16th to endDay
221221213474%
1920
November1st to 15thDay
121212347%71%
1810
16th to endDay
2212222336%70%
1755
December1st to 15thDay
142313346%66%
1589
16th to endDay
3413423448%58%
1664
January1st to 15thNight
2212213246%69%
2549
16th to endNight
3311213346%68%
2704
February1st to 15thNight
2413323335%65%
2357
16th to endNight
2312424346%64%
1894
March1st to 15thNight
3412324446%61%
2036
16th to endNight
4312212335%68%
2064
April1st to 15thNight
322332446%6%61%
1798
16th to endNight
321331334468%
1800
May1st to 15thNight
321342335%8%60%
1799
16th to endNight
2312313447%65%
1553
June1st to 15thNight
1112325%6%6%9%59%
1440
16th to endNight
1124245%7%8%60%
1440
July1st to 15thNight
43145%26%8%10%11%42%
1524
16th to endNight
32146%36%5%8%15%41%
1701
August1st to 15thNight
33145%36%8%9%11%42%
1721
16th to endNight
32145%46%6%9%12%44%
1910
September1st to 15thNight
42145%45%7%9%12%42%
1800
16th to endNight
3313323345%65%
1932
October1st to 15thNight
421331325%6%67%
2160
16th to endNight
221312335%72%
2304
November1st to 15thNight
111212345%74%
2365
16th to endNight
2212312335%70%
2535
December1st to 15thNight
3412213347%65%
2699
16th to endNight
3414323348%59%
2912

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
16%5%11%30%31%4
1731
16th to endDay
18%47%26%33%9%
1872
February1st to 15thDay
19%411%28%25%10%
1757
16th to endDay
18%36%26%32%11%
1580
March1st to 15thDay
20%46%23%32%12%
1923
16th to endDay
19%38%20%34%14%
2159
April1st to 15thDay
20%37%22%30%15%
2150
16th to endDay
18%36%18%34%18%
2160
May1st to 15thDay
19%5%10%17%28%17%
2151
16th to endDay
18%48%18%25%24%
2557
June1st to 15thDay
16%39%17%21%31%
2520
16th to endDay
15%49%18%22%30%
2520
July1st to 15thDay
30%9%15%15%15%12%
2290
16th to endDay
31%10%19%26%10%1
2312
August1st to 15thDay
27%10%17%21%15%6%
2223
16th to endDay
28%9%13%24%17%6%
2292
September1st to 15thDay
30%7%14%22%16%8%
2160
16th to endDay
19%5%6%20%29%18%
2025
October1st to 15thDay
18%5%5%18%30%20%
1800
16th to endDay
14%36%20%35%18%
1920
November1st to 15thDay
12%38%25%36%13%
1810
16th to endDay
16%36%24%36%13%
1755
December1st to 15thDay
18%313%33%24%6%
1589
16th to endDay
24%315%27%24%3
1664
January1st to 15thNight
16%410%32%29%7%
2549
16th to endNight
16%310%24%36%8%
2704
February1st to 15thNight
20%411%28%24%11%
2367
16th to endNight
19%37%21%34%13%
1894
March1st to 15thNight
22%46%25%30%11%
2036
16th to endNight
18%36%19%36%16%
2064
April1st to 15thNight
21%37%21%28%17%
1798
16th to endNight
20%36%18%32%19%
1800
May1st to 15thNight
22%5%10%16%27%17%
1800
16th to endNight
19%5%10%17%23%23%
1554
June1st to 15thNight
20%6%11%14%17%30%
1440
16th to endNight
18%7%11%15%17%29%
1440
July1st to 15thNight
30%11%16%17%12%11%
1437
16th to endNight
30%11%24%22%9%1
1593
August1st to 15thNight
29%12%19%18%13%6%
1712
16th to endNight
28%10%16%24%12%6%
1910
September1st to 15thNight
29%12%17%18%13%8%
1800
16th to endNight
21%5%8%16%27%20%
1932
October1st to 15thNight
18%47%17%28%22%
2160
16th to endNight
15%35%16%36%20%
2304
November1st to 15thNight
12%26%23%39%14%
2365
16th to endNight
17%35%22%34%17%
2535
December1st to 15thNight
19%411%31%27%6%
2699
16th to endNight
23%413%30%24%4
2912

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
5%5%35%34%17%
135
16th to endDay
39%31%30%22%2
144
February1st to 15thDay
414%26%34%19%
126
16th to endDay
7%13%35%27%16%
81
March1st to 15thDay
5%21%30%29%13%
213
16th to endDay
6%29%31%21%9%1
288
April1st to 15thDay
8%24%33%21%8%2
269
16th to endDay
10%27%38%17%5%
270
May1st to 15thDay
319%42%23%10%
288
16th to endDay
5%10%31%36%14%1
474
June1st to 15thDay
27%22%35%28%3
495
16th to endDay
2217%34%37%6%
495
July1st to 15thDay
415%37%32%9%
394
16th to endDay
5%19%26%36%21%
327
August1st to 15thDay
3112%36%33%13%
315
16th to endDay
8%15%34%29%11%
332
September1st to 15thDay
5%323%40%20%6%
315
16th to endDay
47%28%38%19%1
210
October1st to 15thDay
5%10%28%29%20%4
135
16th to endDay
6%6%25%25%28%9%
144
November1st to 15thDay
114%28%33%19%2
135
16th to endDay
8%11%37%25%16%1
135
December1st to 15thDay
413%28%37%14%2
135
16th to endDay
9%10%30%40%8%
144
January1st to 15thNight
4426%45%18%1
807
16th to endNight
46%30%39%17%1
832
February1st to 15thNight
47%31%43%12%
752
16th to endNight
49%41%38%5%
632
March1st to 15thNight
5%8%31%41%12%
720
16th to endNight
311%31%41%12%
720
April1st to 15thNight
314%36%38%6%
539
16th to endNight
412%38%35%9%
540
May1st to 15thNight
49%32%40%12%
540
16th to endNight
36%32%39%17%
563
June1st to 15thNight
1327%46%19%
540
16th to endNight
319%48%27%1
540
July1st to 15thNight
5%10%41%38%3
510
16th to endNight
46%30%51%6%
564
August1st to 15thNight
38%31%47%8%
539
16th to endNight
318%38%42%6%
573
September1st to 15thNight
4212%42%35%2
540
16th to endNight
4319%43%26%2
564
October1st to 15thNight
4324%44%21%2
720
16th to endNight
3422%41%24%3
768
November1st to 15thNight
25%25%42%23%1
845
16th to endNight
37%23%40%21%2
975
December1st to 15thNight
5%9%26%44%13%
975
16th to endNight
5%7%31%44%10%
1040
Page generated at 2018-02-13 18:46:11. Version ac04

Copyright 2018 A. Danko


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