Blue Canyon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Blue Canyon clear sky chart from 2005-11-05 to

2017-09-12
.

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
59%
15159
27%
46812
22%
15123
65%
15123
36%
25829

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
44%
718
20%
2504
15%
716
53%
716
25%
1477
January16th to endNight
40%
768
25%
2496
16%
768
53%
768
23%
1535
February1st to 15thNight
41%
700
22%
2253
15%
697
53%
697
23%
1423
February16th to endNight
44%
632
24%
1895
19%
632
53%
632
24%
1235
March1st to 15thNight
42%
720
15%
2083
10%
720
48%
720
21%
1434
March16th to endNight
44%
768
18%
2041
11%
768
49%
768
26%
1378
April1st to 15thNight
45%
719
18%
1799
8%
719
50%
719
27%
1260
April16th to endNight
56%
720
23%
1800
11%
720
60%
720
38%
1097
May1st to 15thNight
58%
545
26%
1625
18%
545
63%
545
43%
828
May16th to endNight
68%
374
23%
1496
28%
374
71%
374
33%
733
June1st to 15thNight
72%
360
26%
1440
33%
360
77%
360
40%
633
June16th to endNight
83%
360
34%
1440
46%
360
87%
360
60%
509
July1st to 15thNight
93%
340
34%
1360
47%
340
94%
340
71%
431
July16th to endNight
91%
456
40%
1490
44%
428
92%
428
72%
532
August1st to 15thNight
88%
581
37%
1654
30%
578
89%
578
68%
731
August16th to endNight
90%
764
42%
1910
27%
764
91%
764
77%
880
September1st to 15thNight
89%
706
42%
1765
29%
706
90%
706
78%
811
September16th to endNight
78%
656
42%
1772
35%
656
83%
656
64%
836
October1st to 15thNight
63%
660
31%
1980
29%
660
70%
660
45%
1009
October16th to endNight
63%
704
34%
2112
30%
704
72%
704
44%
1094
November1st to 15thNight
59%
700
26%
2275
23%
700
67%
700
34%
1245
November16th to endNight
49%
720
24%
2414
21%
720
56%
720
29%
1388
December1st to 15thNight
41%
720
21%
2520
15%
720
53%
720
21%
1549
December16th to endNight
34%
768
21%
2688
13%
768
46%
768
17%
1781

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
11%5%12212335%59%
47844
Night
12%6%12213335%56%
47002
TransparencyDay
28%27%18%24%17%
47523
Night
30%37%18%22%16%
46823
SeeingDay
16%15%32%22%8%3
5792
Night
15%5%13%31%27%5%
15167

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
16%8%14323336%46%
1432
16th to endDay
19%11%22312336%43%
1728
February1st to 15thDay
21%9%12213346%44%
1600
16th to endDay
21%15%3221235%437%
1579
March1st to 15thDay
20%13%33423346%35%
1875
16th to endDay
20%10%23313446%39%
2181
April1st to 15thDay
19%12%13323446%38%
2149
16th to endDay
14%6%13313335%53%
2160
May1st to 15thDay
8%312212347%61%
2321
16th to endDay
13%5%23313446%51%
2615
June1st to 15thDay
9%413213235%60%
2520
16th to endDay
3111122381%
2520
July1st to 15thDay
111112284%
2520
16th to endDay
11111111284%
2574
August1st to 15thDay
211112283%
2295
16th to endDay
1121286%
2292
September1st to 15thDay
2111222380%
2114
16th to endDay
42111112477%
1854
October1st to 15thDay
10%23213345%62%
1650
16th to endDay
11%31331233459%
1760
November1st to 15thDay
11%5%13423346%51%
1584
16th to endDay
15%8%13324335%47%
1545
December1st to 15thDay
21%8%2421345%6%40%
1440
16th to endDay
23%11%23312335%38%
1536
January1st to 15thNight
15%7%13324347%45%
2504
16th to endNight
17%10%12223335%46%
2496
February1st to 15thNight
17%8%2332435%7%40%
2252
16th to endNight
19%12%23113346%41%
1895
March1st to 15thNight
20%11%23323436%36%
2083
16th to endNight
18%10%12313335%44%
2041
April1st to 15thNight
17%10%2432335%6%39%
1799
16th to endNight
12%6%13213345%56%
1800
May1st to 15thNight
8%21331335%5%61%
1625
16th to endNight
10%313313246%57%
1496
June1st to 15thNight
8%311112335%65%
1440
16th to endNight
21211212280%
1440
July1st to 15thNight
2222383%
1440
16th to endNight
121112383%
1592
August1st to 15thNight
21221213377%
1663
16th to endNight
111222382%
1910
September1st to 15thNight
11111112483%
1765
16th to endNight
32111123476%
1772
October1st to 15thNight
8%31331233465%
1980
16th to endNight
11%2121235%5%61%
2112
November1st to 15thNight
12%413213346%54%
2275
16th to endNight
13%7%13323346%50%
2414
December1st to 15thNight
21%7%12323435%43%
2520
16th to endNight
24%10%23212335%39%
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
40%29%21%19%6%
1432
16th to endDay
43%27%15%18%11%
1728
February1st to 15thDay
41%311%17%20%5%
1600
16th to endDay
48%28%25%12%2
1579
March1st to 15thDay
50%310%12%17%5%
1875
16th to endDay
45%415%17%13%3
2181
April1st to 15thDay
46%312%19%14%2
2149
16th to endDay
32%313%23%21%5%
2160
May1st to 15thDay
22%311%31%24%6%
2321
16th to endDay
32%312%27%19%5%
2619
June1st to 15thDay
26%211%18%23%17%
2520
16th to endDay
10%1317%40%26%
2520
July1st to 15thDay
7%129%29%49%
2371
16th to endDay
9%1211%24%51%
2414
August1st to 15thDay
8%1211%32%42%
2279
16th to endDay
6%1114%39%36%
2292
September1st to 15thDay
9%1311%37%36%
2114
16th to endDay
13%15%24%33%21%
1854
October1st to 15thDay
23%26%25%27%13%
1650
16th to endDay
29%28%20%25%14%
1760
November1st to 15thDay
33%311%21%19%9%
1584
16th to endDay
39%37%20%21%7%
1545
December1st to 15thDay
44%38%19%19%4
1440
16th to endDay
49%39%12%17%7%
1536
January1st to 15thNight
38%39%19%19%9%
2504
16th to endNight
41%27%13%19%15%
2496
February1st to 15thNight
43%37%20%17%8%
2263
16th to endNight
44%38%23%16%4
1895
March1st to 15thNight
48%39%15%14%7%
2083
16th to endNight
42%5%11%20%14%5%
2041
April1st to 15thNight
45%412%21%11%4
1799
16th to endNight
30%412%26%21%4
1800
May1st to 15thNight
23%312%26%26%8%
1626
16th to endNight
27%414%29%18%5%
1496
June1st to 15thNight
20%410%22%23%17%
1440
16th to endNight
12%1416%33%31%
1440
July1st to 15thNight
6%228%25%54%
1360
16th to endNight
8%1311%22%53%
1490
August1st to 15thNight
12%1211%27%44%
1654
16th to endNight
8%1213%33%40%
1910
September1st to 15thNight
8%1312%37%37%
1765
16th to endNight
13%2421%36%21%
1772
October1st to 15thNight
23%26%23%28%15%
1980
16th to endNight
23%36%22%28%14%
2112
November1st to 15thNight
29%411%21%21%11%
2275
16th to endNight
35%38%21%22%9%
2414
December1st to 15thNight
42%38%18%20%6%
2520
16th to endNight
48%37%11%20%8%
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
53%8%20%10%6%1
60
16th to endDay
32%13%22%21%8%1
256
February1st to 15thDay
29%14%27%18%8%
241
16th to endDay
36%12%28%19%3
238
March1st to 15thDay
38%20%17%14%7%1
270
16th to endDay
30%19%28%15%4
288
April1st to 15thDay
31%24%26%13%4
269
16th to endDay
24%23%31%15%4
270
May1st to 15thDay
15%26%32%17%5%1
288
16th to endDay
19%17%28%19%8%5%
330
June1st to 15thDay
15%20%33%20%6%3
315
16th to endDay
5%12%42%25%7%6%
315
July1st to 15thDay
17%44%29%6%9%
305
16th to endDay
11%43%28%11%5%
327
August1st to 15thDay
212%40%29%9%5%
315
16th to endDay
10%39%30%13%6%
332
September1st to 15thDay
310%43%27%12%3
300
16th to endDay
6%12%38%32%7%1
255
October1st to 15thDay
9%21%33%23%9%2
255
16th to endDay
19%12%31%27%8%
272
November1st to 15thDay
12%6%17%24%33%5%
90
16th to endDay
27%15%18%27%10%1
77
December1st to 15thDay
36%20%20%16%6%
60
16th to endDay
28%125%26%15%3
64
January1st to 15thNight
22%6%20%29%16%5%
720
16th to endNight
24%11%17%26%17%2
768
February1st to 15thNight
23%7%19%30%16%1
704
16th to endNight
27%9%14%28%16%3
632
March1st to 15thNight
27%7%15%27%19%2
720
16th to endNight
25%8%17%26%20%2
768
April1st to 15thNight
23%5%17%32%18%2
719
16th to endNight
16%7%14%34%21%5%
720
May1st to 15thNight
9%8%17%33%26%3
546
16th to endNight
13%28%32%36%6%
375
June1st to 15thNight
8%5%10%35%36%4
360
16th to endNight
317%38%45%4
360
July1st to 15thNight
230%60%6%
340
16th to endNight
228%57%10%
456
August1st to 15thNight
2337%46%8%
581
16th to endNight
1437%46%8%
764
September1st to 15thNight
2436%45%10%
706
16th to endNight
4310%35%33%12%
656
October1st to 15thNight
10%5%14%32%30%7%
660
16th to endNight
13%5%13%30%29%7%
704
November1st to 15thNight
13%5%15%32%26%6%
700
16th to endNight
17%7%20%29%20%4
720
December1st to 15thNight
25%9%16%31%14%2
720
16th to endNight
31%10%18%24%13%1
768
Page generated at 2017-09-13 04:39:22. Version ac04

Copyright 2017 A. Danko


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