Ritter Butte
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ritter Butte clear sky chart from 2005-11-05 to 2018-10-08.

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
51%
15997
15%
51014
15%
15970
52%
15970
21%
34580

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
36%
776
9%
2716
9%
776
38%
776
11%
2118
January16th to endNight
43%
832
12%
2912
12%
832
44%
832
14%
2139
February1st to 15thNight
37%
761
7%
2489
7%
758
38%
758
10%
1987
February16th to endNight
34%
684
11%
2051
10%
684
36%
684
12%
1625
March1st to 15thNight
37%
780
8%
2340
8%
780
39%
780
13%
1843
March16th to endNight
32%
832
8%
2168
6%
832
32%
832
13%
1759
April1st to 15thNight
38%
779
9%
1949
5%
779
38%
779
16%
1559
April16th to endNight
46%
687
14%
1845
10%
687
47%
687
22%
1325
May1st to 15thNight
55%
428
18%
1598
20%
428
59%
428
23%
972
May16th to endNight
57%
406
10%
1624
15%
406
59%
406
16%
1082
June1st to 15thNight
58%
390
12%
1560
18%
390
60%
390
20%
964
June16th to endNight
66%
390
16%
1560
26%
390
69%
390
30%
807
July1st to 15thNight
82%
370
21%
1480
34%
370
87%
370
50%
598
July16th to endNight
89%
408
31%
1544
46%
386
92%
386
63%
532
August1st to 15thNight
89%
418
33%
1562
38%
416
90%
416
53%
642
August16th to endNight
80%
828
34%
2070
22%
828
81%
828
65%
1032
September1st to 15thNight
81%
780
37%
1950
23%
780
83%
780
66%
965
September16th to endNight
66%
776
27%
2116
23%
776
67%
776
38%
1269
October1st to 15thNight
55%
752
19%
2223
19%
752
58%
752
27%
1440
October16th to endNight
52%
768
18%
2434
19%
768
55%
768
21%
1643
November1st to 15thNight
40%
760
12%
2470
11%
760
43%
760
14%
1866
November16th to endNight
39%
780
9%
2711
9%
780
40%
780
13%
2052
December1st to 15thNight
41%
780
10%
2730
10%
780
42%
780
13%
2048
December16th to endNight
31%
832
9%
2912
10%
832
32%
832
10%
2313

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
10%9%35%424446%43%
52139
Night
12%10%35%424446%41%
51182
Cloud CoverDay
11%10%35%424346%42%
52139
Night
13%11%35%424346%40%
51186
TransparencyDay
44%5%10%18%15%5%
51810
Night
46%6%10%18%13%4
51015
SeeingDay
18%12%27%25%13%3
6791
Night
20%6%15%31%21%3
16006

By Month

Percentage Cloud Cover NW (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%12%46%5%36%6%6%7%23%
1552
16th to endDay
16%12%46%425%45%7%28%
1664
February1st to 15thDay
15%15%5%8%5%25%5%46%25%
1701
16th to endDay
12%14%5%8%8%345%6%7%22%
1709
March1st to 15thDay
13%15%49%7%46%6%5%5%21%
1950
16th to endDay
12%16%6%9%7%5%5%5%5%6%20%
2405
April1st to 15thDay
12%16%5%8%6%35%45%6%24%
2329
16th to endDay
11%10%46%6%3445%6%36%
2389
May1st to 15thDay
9%8%36%5%2345%7%41%
2680
16th to endDay
15%9%36%6%35%446%34%
2839
June1st to 15thDay
14%7%25%5%34446%40%
2730
16th to endDay
8%413323346%57%
2730
July1st to 15thDay
2112313445%69%
2730
16th to endDay
111212235%77%
2881
August1st to 15thDay
2212212235%73%
2641
16th to endDay
221221233474%
2484
September1st to 15thDay
2211212225%73%
2340
16th to endDay
9%5%34323345%52%
2174
October1st to 15thDay
15%8%2443335%6%42%
1902
16th to endDay
17%8%36%5%34346%38%
1788
November1st to 15thDay
18%13%37%43445%8%26%
1719
16th to endDay
15%16%47%5%3345%7%26%
1578
December1st to 15thDay
13%15%6%6%6%34445%27%
1560
16th to endDay
18%19%5%8%5%34435%21%
1664
January1st to 15thNight
19%13%5%7%6%23445%25%
2716
16th to endNight
17%13%46%5%2445%6%30%
2912
February1st to 15thNight
15%14%5%8%6%35%45%5%25%
2477
16th to endNight
11%18%6%9%5%34436%26%
2051
March1st to 15thNight
15%13%5%7%6%245%5%6%26%
2340
16th to endNight
12%14%5%8%6%45%46%6%25%
2164
April1st to 15thNight
13%13%45%6%245%5%7%29%
1949
16th to endNight
11%11%35%334446%40%
1845
May1st to 15thNight
9%6%25%42445%6%48%
1598
16th to endNight
11%8%35%6%46%45%6%39%
1624
June1st to 15thNight
14%5%13424347%47%
1560
16th to endNight
7%313323346%57%
1560
July1st to 15thNight
112213346%71%
1560
16th to endNight
111224480%
1640
August1st to 15thNight
211223345%71%
1570
16th to endNight
22121223478%
2070
September1st to 15thNight
32111225%77%
1950
16th to endNight
7%425%3225%46%54%
2116
October1st to 15thNight
11%8%24432346%47%
2223
16th to endNight
14%8%25%5%33345%42%
2434
November1st to 15thNight
19%11%45%6%3445%7%27%
2470
16th to endNight
18%12%46%5%24445%29%
2711
December1st to 15thNight
15%14%46%5%3445%5%30%
2730
16th to endNight
18%17%5%7%434445%23%
2912

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
18%12%47%435%5%5%7%23%
1552
16th to endDay
17%13%46%5%25%447%28%
1664
February1st to 15thDay
17%15%5%8%5%25%435%25%
1701
16th to endDay
13%16%7%8%5%35%5%5%5%22%
1709
March1st to 15thDay
14%17%5%9%7%45%6%4420%
1950
16th to endDay
13%19%6%10%7%36%44419%
2405
April1st to 15thDay
13%18%6%7%6%35%346%23%
2329
16th to endDay
12%13%47%5%34445%34%
2389
May1st to 15thDay
10%9%36%5%2445%7%39%
2680
16th to endDay
17%10%36%6%35%45%6%31%
2839
June1st to 15thDay
16%7%35%5%245%46%39%
2730
16th to endDay
9%5%13323346%56%
2730
July1st to 15thDay
2212214345%69%
2730
16th to endDay
1111212226%76%
2881
August1st to 15thDay
222212245%72%
2641
16th to endDay
2212212235%73%
2484
September1st to 15thDay
321221223472%
2340
16th to endDay
10%6%24323345%52%
2174
October1st to 15thDay
15%9%25%423346%41%
1902
16th to endDay
18%8%26%5%33245%38%
1788
November1st to 15thDay
20%14%46%42336%8%25%
1719
16th to endDay
17%16%5%6%5%33447%25%
1578
December1st to 15thDay
15%18%46%5%33445%27%
1560
16th to endDay
20%21%6%8%42333421%
1664
January1st to 15thNight
21%13%5%7%5%24335%26%
2716
16th to endNight
18%14%46%42435%6%29%
2912
February1st to 15thNight
17%16%47%5%345%5%5%24%
2477
16th to endNight
12%20%6%9%434435%24%
2051
March1st to 15thNight
16%14%5%7%5%345%5%6%25%
2340
16th to endNight
14%16%5%8%7%35%35%6%23%
2168
April1st to 15thNight
14%14%47%6%35%347%28%
1949
16th to endNight
12%13%35%434347%39%
1845
May1st to 15thNight
9%7%244345%36%47%
1598
16th to endNight
12%8%35%5%35%347%38%
1624
June1st to 15thNight
15%6%23424447%45%
1560
16th to endNight
8%423324347%55%
1560
July1st to 15thNight
11221325%6%71%
1560
16th to endNight
112235%79%
1640
August1st to 15thNight
21121235%7%70%
1570
16th to endNight
22121223477%
2070
September1st to 15thNight
3211111235%76%
1950
16th to endNight
8%6%14323336%54%
2116
October1st to 15thNight
13%8%34432345%46%
2223
16th to endNight
16%8%26%424345%41%
2434
November1st to 15thNight
21%12%35%5%3445%5%27%
2470
16th to endNight
19%15%36%424435%29%
2711
December1st to 15thNight
16%15%46%424445%29%
2730
16th to endNight
20%19%5%7%5%23345%22%
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
59%8%11%14%5%
1552
16th to endDay
55%8%13%13%6%3
1664
February1st to 15thDay
61%7%13%11%5%
1701
16th to endDay
65%7%10%11%3
1709
March1st to 15thDay
67%7%9%10%4
1950
16th to endDay
69%7%8%12%2
2405
April1st to 15thDay
63%6%12%13%3
2329
16th to endDay
53%5%11%18%10%
2389
May1st to 15thDay
44%7%11%25%10%
2680
16th to endDay
55%7%11%19%5%
2843
June1st to 15thDay
47%5%10%23%11%2
2730
16th to endDay
30%410%29%20%4
2730
July1st to 15thDay
17%48%19%30%18%
2581
16th to endDay
12%36%12%35%29%
2714
August1st to 15thDay
14%46%21%35%16%
2624
16th to endDay
15%38%24%35%13%
2484
September1st to 15thDay
16%36%24%35%13%
2340
16th to endDay
35%5%8%22%22%5%
2174
October1st to 15thDay
44%5%11%19%16%2
1902
16th to endDay
49%5%10%19%14%
1788
November1st to 15thDay
58%6%11%16%6%
1719
16th to endDay
60%6%12%13%7%1
1578
December1st to 15thDay
59%7%12%13%5%1
1560
16th to endDay
67%6%10%11%3
1664
January1st to 15thNight
61%6%10%13%6%
2716
16th to endNight
56%6%10%14%7%4
2912
February1st to 15thNight
62%8%11%10%6%
2489
16th to endNight
63%6%9%13%6%1
2051
March1st to 15thNight
60%7%9%16%41
2340
16th to endNight
61%7%13%14%2
2168
April1st to 15thNight
57%8%11%17%4
1949
16th to endNight
47%6%13%19%11%
1845
May1st to 15thNight
39%6%13%29%10%
1599
16th to endNight
47%7%16%20%7%
1624
June1st to 15thNight
40%7%12%23%12%2
1560
16th to endNight
29%5%12%31%15%5%
1560
July1st to 15thNight
14%5%11%21%29%17%
1480
16th to endNight
9%27%18%37%24%
1544
August1st to 15thNight
15%47%23%31%17%
1562
16th to endNight
13%37%25%36%13%
2070
September1st to 15thNight
13%36%28%34%13%
1950
16th to endNight
32%49%23%22%7%
2116
October1st to 15thNight
41%5%10%22%17%3
2223
16th to endNight
46%5%11%14%18%2
2434
November1st to 15thNight
56%8%9%15%9%
2470
16th to endNight
58%7%10%12%10%1
2711
December1st to 15thNight
57%7%12%14%7%1
2730
16th to endNight
64%6%9%13%5%
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
23%5%20%21%24%5%
90
16th to endDay
29%12%31%13%12%1
96
February1st to 15thDay
28%16%21%21%8%2
269
16th to endDay
25%18%30%18%6%
290
March1st to 15thDay
29%19%26%17%6%
330
16th to endDay
30%18%28%18%3
352
April1st to 15thDay
23%21%28%16%7%3
329
16th to endDay
25%17%26%18%9%2
318
May1st to 15thDay
19%17%25%23%11%2
348
16th to endDay
24%7%24%22%16%5%
394
June1st to 15thDay
16%14%26%23%14%4
375
16th to endDay
10%12%31%29%12%3
375
July1st to 15thDay
6%7%31%33%19%3
365
16th to endDay
110%37%30%16%4
391
August1st to 15thDay
5%5%26%35%18%7%
359
16th to endDay
47%24%32%20%10%
396
September1st to 15thDay
6%7%25%30%22%7%
375
16th to endDay
14%8%25%29%18%3
375
October1st to 15thDay
20%11%26%26%12%2
345
16th to endDay
28%9%19%25%13%2
204
November1st to 15thDay
25%17%26%27%3
135
16th to endDay
35%14%22%21%5%1
94
December1st to 15thDay
31%14%20%14%11%8%
90
16th to endDay
31%15%21%20%10%
96
January1st to 15thNight
28%8%17%24%19%1
780
16th to endNight
26%6%15%31%17%2
832
February1st to 15thNight
25%7%19%31%14%1
764
16th to endNight
23%12%20%27%15%1
684
March1st to 15thNight
24%10%21%24%15%2
780
16th to endNight
24%11%23%26%12%
832
April1st to 15thNight
21%10%20%30%13%2
779
16th to endNight
21%7%19%26%20%3
687
May1st to 15thNight
15%419%32%24%3
429
16th to endNight
17%5%9%31%30%4
407
June1st to 15thNight
18%315%37%21%3
390
16th to endNight
11%214%40%30%1
390
July1st to 15thNight
48%46%36%2
370
16th to endNight
17%51%36%2
408
August1st to 15thNight
3340%46%5%
418
16th to endNight
3110%37%38%7%
828
September1st to 15thNight
5%27%37%39%8%
780
16th to endNight
13%212%32%30%8%
776
October1st to 15thNight
20%314%34%21%5%
752
16th to endNight
22%5%14%30%21%6%
768
November1st to 15thNight
28%7%16%33%12%1
760
16th to endNight
30%8%15%24%15%5%
780
December1st to 15thNight
26%6%16%29%18%2
780
16th to endNight
31%10%20%26%9%1
832
Page generated at 2018-10-09 07:39:17. Version ac04

Copyright 2018 A. Danko


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