Annbar Canyon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Annbar Canyon clear sky chart from 2005-11-05 to 2018-01-12.

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
66%
16099
34%
48356
27%
16058
73%
16058
51%
23375

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
57%
764
30%
2471
26%
760
66%
760
43%
1232
January16th to endNight
57%
768
34%
2496
29%
768
68%
768
41%
1277
February1st to 15thNight
62%
700
32%
2202
29%
700
69%
700
49%
1065
February16th to endNight
50%
632
35%
1895
28%
632
62%
632
44%
994
March1st to 15thNight
57%
720
36%
2000
25%
720
68%
720
53%
1003
March16th to endNight
59%
768
34%
2112
23%
768
69%
768
52%
1074
April1st to 15thNight
49%
704
29%
1963
14%
704
60%
704
50%
1013
April16th to endNight
57%
540
42%
1632
26%
540
71%
540
60%
699
May1st to 15thNight
60%
540
35%
1619
24%
539
68%
539
57%
726
May16th to endNight
60%
561
34%
1684
22%
561
69%
561
57%
753
June1st to 15thNight
67%
540
31%
1620
25%
540
72%
540
67%
679
June16th to endNight
82%
540
34%
1620
30%
540
84%
540
75%
639
July1st to 15thNight
83%
510
22%
1530
20%
510
83%
510
47%
774
July16th to endNight
81%
564
20%
1593
18%
531
81%
531
35%
932
August1st to 15thNight
80%
539
30%
1611
26%
536
81%
536
49%
802
August16th to endNight
84%
633
35%
1821
29%
633
85%
633
50%
945
September1st to 15thNight
80%
720
29%
1980
24%
720
81%
720
48%
1089
September16th to endNight
76%
716
46%
1980
32%
716
85%
716
70%
872
October1st to 15thNight
67%
720
36%
2058
25%
720
76%
720
63%
939
October16th to endNight
74%
768
43%
2304
36%
768
81%
768
62%
1021
November1st to 15thNight
65%
760
36%
2391
28%
760
75%
760
56%
1074
November16th to endNight
65%
780
40%
2535
36%
780
75%
780
55%
1105
December1st to 15thNight
62%
780
33%
2535
29%
780
72%
780
46%
1228
December16th to endNight
58%
832
32%
2704
28%
832
65%
832
37%
1440

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
3313323346%63%
48979
Night
3312223346%67%
48552
TransparencyDay
22%47%17%27%20%
48674
Night
18%48%19%29%20%
48358
SeeingDay
6%9%23%30%21%8%
5812
Night
4420%35%29%5%
16105

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
3413323245%64%
1710
16th to endDay
5%5%12313337%62%
1728
February1st to 15thDay
28%12312337%62%
1658
16th to endDay
47%24313436%56%
1579
March1st to 15thDay
3411214346%65%
1959
16th to endDay
332221335%6%65%
2112
April1st to 15thDay
2413424445%63%
1984
16th to endDay
2312213326%70%
2325
May1st to 15thDay
2212422336%68%
2331
16th to endDay
331231343467%
2429
June1st to 15thDay
1121223479%
2340
16th to endDay
11221223476%
2340
July1st to 15thDay
4315%5%37%46%7%49%
2340
16th to endDay
6%436%6%47%8%7%9%34%
2467
August1st to 15thDay
5%415%6%46%5%5%7%45%
2340
16th to endDay
44146%46%6%5%6%49%
2378
September1st to 15thDay
43145%35%446%54%
1980
16th to endDay
222213245%72%
1980
October1st to 15thDay
121232233473%
1900
16th to endDay
22321222474%
1920
November1st to 15thDay
1212112336%72%
1797
16th to endDay
441221112472%
1755
December1st to 15thDay
35%13322346%63%
1755
16th to endDay
5%7%23323447%55%
1872
January1st to 15thNight
4423322335%63%
2471
16th to endNight
6%5%23222335%62%
2496
February1st to 15thNight
2413312235%67%
2191
16th to endNight
45%13213445%62%
1895
March1st to 15thNight
231221346%6%65%
2000
16th to endNight
231221345%6%66%
2112
April1st to 15thNight
3313323236%67%
1963
16th to endNight
111112336%75%
1632
May1st to 15thNight
221212335%74%
1619
16th to endNight
1112213335%72%
1684
June1st to 15thNight
1122335%77%
1620
16th to endNight
11111223480%
1620
July1st to 15thNight
22123345%5%7%60%
1620
16th to endNight
23145%45%7%9%11%44%
1701
August1st to 15thNight
221332345%8%61%
1620
16th to endNight
21343345%7%63%
1821
September1st to 15thNight
22134245%5%6%61%
1980
16th to endNight
21111113380%
1980
October1st to 15thNight
211112335%74%
2058
16th to endNight
1112212245%74%
2304
November1st to 15thNight
1212312236%71%
2391
16th to endNight
3211212235%71%
2535
December1st to 15thNight
3412212446%65%
2535
16th to endNight
5%7%12323347%57%
2704

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%37%22%34%8%
1711
16th to endDay
24%39%19%32%10%
1728
February1st to 15thDay
23%37%25%21%17%
1658
16th to endDay
29%38%18%28%11%
1579
March1st to 15thDay
20%36%23%34%12%
1959
16th to endDay
20%37%23%30%14%
2112
April1st to 15thDay
21%46%19%31%15%
1984
16th to endDay
17%25%19%34%20%
2325
May1st to 15thDay
18%27%18%34%17%
2331
16th to endDay
20%45%14%35%19%
2432
June1st to 15thDay
10%248%27%46%
2340
16th to endDay
12%236%22%52%
2340
July1st to 15thDay
32%7%9%11%14%24%
2201
16th to endDay
40%12%14%12%13%6%
2312
August1st to 15thDay
35%7%10%12%17%15%
2325
16th to endDay
32%7%8%15%23%12%
2378
September1st to 15thDay
28%5%11%15%18%20%
1980
16th to endDay
15%36%15%30%28%
1980
October1st to 15thDay
16%35%15%28%30%
1900
16th to endDay
15%25%15%37%23%
1920
November1st to 15thDay
15%26%24%31%19%
1797
16th to endDay
18%16%19%33%19%
1755
December1st to 15thDay
22%412%24%25%11%
1755
16th to endDay
29%410%22%25%8%
1872
January1st to 15thNight
23%46%24%32%9%
2471
16th to endNight
25%37%21%29%12%
2496
February1st to 15thNight
19%49%24%25%16%
2202
16th to endNight
23%45%22%30%12%
1895
March1st to 15thNight
18%36%22%38%10%
2000
16th to endNight
18%48%22%32%13%
2112
April1st to 15thNight
19%36%17%36%15%
1963
16th to endNight
11%25%21%37%20%
1632
May1st to 15thNight
13%3419%36%21%
1620
16th to endNight
14%26%17%38%20%
1685
June1st to 15thNight
11%147%29%45%
1620
16th to endNight
8%146%22%57%
1620
July1st to 15thNight
19%7%14%15%15%29%
1530
16th to endNight
27%10%18%18%15%9%
1593
August1st to 15thNight
20%5%11%22%20%19%
1611
16th to endNight
19%5%10%21%25%16%
1821
September1st to 15thNight
20%7%11%18%20%21%
1980
16th to endNight
9%2414%33%35%
1980
October1st to 15thNight
12%37%17%29%29%
2058
16th to endNight
13%35%14%35%28%
2304
November1st to 15thNight
16%27%21%33%19%
2391
16th to endNight
15%26%20%31%22%
2535
December1st to 15thNight
20%49%25%25%14%
2535
16th to endNight
27%5%11%21%25%8%
2704

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
19%17%21%30%11%
123
16th to endDay
9%9%18%31%19%11%
96
February1st to 15thDay
6%8%34%26%19%4
173
16th to endDay
11%21%32%19%13%1
238
March1st to 15thDay
5%15%27%29%18%3
270
16th to endDay
6%17%29%27%16%3
288
April1st to 15thDay
7%20%29%23%12%6%
269
16th to endDay
5%25%31%23%10%4
270
May1st to 15thDay
414%34%29%12%3
288
16th to endDay
7%13%27%26%20%4
330
June1st to 15thDay
38%31%31%14%10%
315
16th to endDay
4315%40%25%10%
315
July1st to 15thDay
4218%40%26%8%
305
16th to endDay
9%9%34%34%12%
327
August1st to 15thDay
7%10%37%28%14%
315
16th to endDay
6%10%31%31%18%
332
September1st to 15thDay
5%318%32%30%9%
315
16th to endDay
6%7%20%31%24%10%
315
October1st to 15thDay
212%37%25%14%8%
235
16th to endDay
7%5%15%31%27%12%
144
November1st to 15thDay
38%18%35%25%8%
135
16th to endDay
10%5%25%34%16%7%
135
December1st to 15thDay
211%22%33%21%8%
135
16th to endDay
9%8%23%34%17%6%
144
January1st to 15thNight
7%7%23%34%20%6%
764
16th to endNight
7%6%23%35%21%4
768
February1st to 15thNight
5%323%41%21%3
704
16th to endNight
6%8%33%33%17%2
632
March1st to 15thNight
46%29%33%22%3
720
16th to endNight
45%27%36%22%4
768
April1st to 15thNight
39%32%32%18%2
704
16th to endNight
38%29%38%16%4
540
May1st to 15thNight
35%29%40%19%2
540
16th to endNight
36%25%36%26%2
563
June1st to 15thNight
1224%44%25%2
540
16th to endNight
2111%42%39%2
540
July1st to 15thNight
4335%49%6%
510
16th to endNight
4426%55%9%
564
August1st to 15thNight
4429%53%7%
539
16th to endNight
3426%51%13%
633
September1st to 15thNight
36%28%49%10%
720
16th to endNight
2314%31%36%11%
716
October1st to 15thNight
3323%38%25%5%
720
16th to endNight
2217%35%30%10%
768
November1st to 15thNight
3323%37%25%5%
760
16th to endNight
45%21%37%23%7%
780
December1st to 15thNight
6%6%21%37%24%3
780
16th to endNight
10%6%21%37%20%3
832
Page generated at 2018-01-12 20:01:29. Version ac04

Copyright 2018 A. Danko


Annbar Canyon Clear Sky Chart |Charts Home