AVAC Kings Canyon Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the AVAC Kings Canyon Site clear sky chart from 2005-11-05 to 2018-03-11.

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
62%
16441
37%
49024
26%
16392
73%
16392
57%
22059

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
52%
780
29%
2680
23%
776
64%
776
40%
1293
January16th to endNight
51%
832
35%
2617
24%
832
67%
832
42%
1304
February1st to 15thNight
54%
760
36%
2288
25%
758
69%
758
49%
1093
February16th to endNight
48%
684
34%
2051
26%
684
61%
684
42%
1054
March1st to 15thNight
50%
764
29%
2292
20%
764
64%
764
44%
1140
March16th to endNight
49%
768
34%
1996
17%
768
63%
768
54%
1001
April1st to 15thNight
42%
719
34%
1799
12%
719
55%
719
50%
943
April16th to endNight
47%
720
36%
1800
12%
720
58%
720
60%
860
May1st to 15thNight
51%
624
35%
1703
17%
623
60%
623
63%
756
May16th to endNight
47%
561
35%
1685
17%
561
61%
561
60%
694
June1st to 15thNight
62%
397
38%
1477
30%
397
76%
397
71%
477
June16th to endNight
73%
360
43%
1440
44%
360
83%
360
81%
416
July1st to 15thNight
90%
340
37%
1360
42%
340
93%
340
69%
435
July16th to endNight
91%
575
39%
1599
33%
537
91%
537
70%
665
August1st to 15thNight
86%
717
38%
1790
24%
713
87%
713
82%
794
August16th to endNight
90%
764
47%
1910
30%
764
92%
764
83%
849
September1st to 15thNight
87%
720
44%
1813
33%
720
90%
720
81%
811
September16th to endNight
79%
716
50%
1980
40%
716
88%
716
81%
795
October1st to 15thNight
66%
720
39%
2025
28%
720
79%
720
62%
910
October16th to endNight
68%
768
46%
2322
38%
768
82%
768
63%
989
November1st to 15thNight
65%
760
37%
2470
31%
760
78%
760
58%
1044
November16th to endNight
64%
780
40%
2535
36%
780
75%
780
53%
1131
December1st to 15thNight
54%
780
36%
2535
25%
780
69%
780
45%
1203
December16th to endNight
51%
832
33%
2857
26%
832
64%
832
36%
1402

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
212212236%72%
49587
Night
212212347%71%
49218
TransparencyDay
14%25%17%29%30%
49276
Night
14%26%19%30%26%
49029
SeeingDay
414%32%32%12%3
6504
Night
37%23%36%24%4
16447

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
4413324347%60%
1585
16th to endDay
7%424413337%58%
1956
February1st to 15thDay
331232335%7%63%
1901
16th to endDay
6%42431435%5%58%
1709
March1st to 15thDay
321222445%9%60%
1904
16th to endDay
22123233410%61%
2224
April1st to 15thDay
4312213247%66%
2149
16th to endDay
112112348%72%
2160
May1st to 15thDay
111111246%76%
2245
16th to endDay
111212337%74%
2429
June1st to 15thDay
11211225%80%
2478
16th to endDay
111288%
2520
July1st to 15thDay
1111222481%
2520
16th to endDay
21211123478%
2452
August1st to 15thDay
11111385%
2160
16th to endDay
111122483%
2292
September1st to 15thDay
11113484%
2145
16th to endDay
111112385%
1980
October1st to 15thDay
211212235%76%
1932
16th to endDay
12212335%76%
1901
November1st to 15thDay
21131335%6%70%
1719
16th to endDay
3212313347%65%
1755
December1st to 15thDay
421331336%9%60%
1755
16th to endDay
6%31432435%7%57%
1716
January1st to 15thNight
431332345%9%57%
2680
16th to endNight
5%323313348%60%
2617
February1st to 15thNight
321231235%8%64%
2281
16th to endNight
5%312323447%60%
2051
March1st to 15thNight
221232346%10%59%
2292
16th to endNight
22122123410%65%
1996
April1st to 15thNight
221221335%7%67%
1799
16th to endNight
1111111349%73%
1800
May1st to 15thNight
111226%11%71%
1703
16th to endNight
11121123480%
1684
June1st to 15thNight
111137%82%
1477
16th to endNight
12390%
1440
July1st to 15thNight
11212483%
1440
16th to endNight
12111335%77%
1711
August1st to 15thNight
11112386%
1800
16th to endNight
1122385%
1910
September1st to 15thNight
1112484%
1813
16th to endNight
112487%
1980
October1st to 15thNight
111212336%75%
2025
16th to endNight
112112246%76%
2322
November1st to 15thNight
111212347%71%
2470
16th to endNight
221121345%8%66%
2535
December1st to 15thNight
431231335%8%63%
2535
16th to endNight
5%31332445%9%57%
2857

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
24%38%22%26%15%
1585
16th to endDay
28%37%20%22%17%
1956
February1st to 15thDay
21%35%20%30%18%
1901
16th to endDay
27%2422%33%9%
1709
March1st to 15thDay
20%39%27%24%15%
1904
16th to endDay
20%210%27%23%14%
2224
April1st to 15thDay
18%29%28%28%11%
2149
16th to endDay
12%210%23%32%18%
2160
May1st to 15thDay
10%26%22%33%24%
2245
16th to endDay
11%2422%40%17%
2432
June1st to 15thDay
8%2414%30%40%
2478
16th to endDay
6%115%21%63%
2520
July1st to 15thDay
9%117%20%58%
2371
16th to endDay
11%1214%29%40%
2301
August1st to 15thDay
8%17%26%56%
2146
16th to endDay
6%16%32%51%
2292
September1st to 15thDay
6%1111%29%49%
2145
16th to endDay
6%18%39%42%
1980
October1st to 15thDay
13%1217%30%34%
1932
16th to endDay
11%2414%30%36%
1901
November1st to 15thDay
14%25%21%36%19%
1719
16th to endDay
18%36%20%28%22%
1755
December1st to 15thDay
20%27%22%28%17%
1755
16th to endDay
27%38%23%23%12%
1716
January1st to 15thNight
23%37%21%28%15%
2680
16th to endNight
23%28%19%25%20%
2617
February1st to 15thNight
19%27%20%27%22%
2292
16th to endNight
24%36%22%31%11%
2051
March1st to 15thNight
20%49%24%24%17%
2292
16th to endNight
16%212%30%25%12%
1996
April1st to 15thNight
17%29%33%25%11%
1799
16th to endNight
10%29%29%32%15%
1800
May1st to 15thNight
9%27%26%37%16%
1704
16th to endNight
9%28%25%38%15%
1685
June1st to 15thNight
5%15%19%32%34%
1477
16th to endNight
428%26%57%
1440
July1st to 15thNight
8%1210%23%54%
1360
16th to endNight
10%2317%27%38%
1599
August1st to 15thNight
6%19%30%51%
1790
16th to endNight
5%117%39%44%
1910
September1st to 15thNight
6%129%34%44%
1813
16th to endNight
5%111%43%37%
1980
October1st to 15thNight
12%1315%33%32%
2025
16th to endNight
12%2315%28%38%
2322
November1st to 15thNight
13%25%21%34%22%
2470
16th to endNight
16%25%19%31%24%
2535
December1st to 15thNight
21%27%19%29%20%
2535
16th to endNight
24%38%22%26%13%
2857

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
6%24%33%30%4
123
16th to endDay
9%20%33%22%12%
324
February1st to 15thDay
6%21%28%28%11%3
326
16th to endDay
10%26%30%22%8%1
290
March1st to 15thDay
8%24%34%18%11%1
312
16th to endDay
7%24%33%22%9%2
288
April1st to 15thDay
11%23%35%18%7%4
269
16th to endDay
7%35%33%15%5%3
270
May1st to 15thDay
5%17%38%27%7%3
288
16th to endDay
416%39%27%8%2
330
June1st to 15thDay
211%39%33%9%4
315
16th to endDay
2336%39%13%3
315
July1st to 15thDay
230%44%20%2
305
16th to endDay
222%51%18%4
327
August1st to 15thDay
1428%48%12%3
315
16th to endDay
125%50%14%8%
332
September1st to 15thDay
5%33%42%13%3
315
16th to endDay
8%34%37%16%3
315
October1st to 15thDay
214%38%32%11%
315
16th to endDay
313%30%27%22%2
317
November1st to 15thDay
211%20%37%17%10%
135
16th to endDay
5%16%25%31%18%2
135
December1st to 15thDay
217%29%30%20%
135
16th to endDay
8%27%15%26%18%2
108
January1st to 15thNight
6%7%27%35%18%4
780
16th to endNight
8%8%25%36%17%3
832
February1st to 15thNight
47%27%32%21%6%
764
16th to endNight
8%9%30%32%15%3
684
March1st to 15thNight
411%30%33%17%3
764
16th to endNight
413%30%33%15%3
768
April1st to 15thNight
415%33%29%15%2
719
16th to endNight
215%33%30%15%2
720
May1st to 15thNight
11%33%35%16%2
624
16th to endNight
212%34%31%17%
563
June1st to 15thNight
7%28%48%14%
397
16th to endNight
124%47%25%1
360
July1st to 15thNight
15%50%39%2
340
16th to endNight
1346%42%6%
575
August1st to 15thNight
19%42%41%5%
717
16th to endNight
6%33%48%10%
764
September1st to 15thNight
8%36%45%8%
720
16th to endNight
314%39%33%8%
716
October1st to 15thNight
17%21%40%24%4
720
16th to endNight
1421%34%27%10%
768
November1st to 15thNight
2423%39%23%6%
760
16th to endNight
3423%35%24%7%
780
December1st to 15thNight
5%7%27%34%20%3
780
16th to endNight
9%10%23%35%17%2
832
Page generated at 2018-03-12 10:28:08. Version ac04

Copyright 2018 A. Danko


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