Ridgecrest
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ridgecrest clear sky chart from 2005-11-05 to 2017-09-21.

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
71%
15649
39%
46845
31%
15612
79%
15612
65%
19771

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
70%
716
30%
2506
30%
716
77%
716
53%
1059
January16th to endNight
65%
768
39%
2415
33%
768
75%
768
51%
1115
February1st to 15thNight
66%
696
36%
2101
32%
696
74%
696
55%
976
February16th to endNight
61%
632
38%
1895
33%
632
73%
632
53%
888
March1st to 15thNight
62%
720
35%
2160
28%
720
75%
720
60%
921
March16th to endNight
59%
768
40%
2016
24%
768
71%
768
65%
937
April1st to 15thNight
54%
719
37%
1799
16%
719
66%
719
60%
877
April16th to endNight
60%
720
41%
1800
17%
720
70%
720
70%
830
May1st to 15thNight
60%
563
40%
1643
25%
563
68%
563
75%
635
May16th to endNight
60%
561
38%
1685
24%
561
69%
561
72%
644
June1st to 15thNight
67%
420
38%
1500
33%
420
77%
420
77%
482
June16th to endNight
78%
360
42%
1440
44%
360
88%
360
82%
410
July1st to 15thNight
87%
340
36%
1360
41%
340
91%
340
65%
457
July16th to endNight
88%
513
39%
1542
36%
480
89%
480
65%
634
August1st to 15thNight
83%
717
38%
1790
23%
713
85%
713
82%
788
August16th to endNight
86%
764
46%
1910
29%
764
88%
764
82%
847
September1st to 15thNight
85%
720
43%
1839
30%
720
89%
720
77%
828
September16th to endNight
82%
680
50%
1881
40%
680
91%
680
85%
732
October1st to 15thNight
75%
660
43%
1820
35%
660
84%
660
71%
789
October16th to endNight
77%
704
45%
2175
41%
704
87%
704
73%
842
November1st to 15thNight
79%
700
39%
2275
39%
700
86%
700
65%
905
November16th to endNight
75%
720
41%
2340
40%
720
82%
720
65%
924
December1st to 15thNight
70%
720
37%
2340
33%
720
77%
720
52%
1026
December16th to endNight
64%
768
34%
2613
31%
768
72%
768
45%
1225

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
111112235%77%
48002
Night
111112235%77%
47041
TransparencyDay
10%25%16%28%37%
47686
Night
11%25%18%29%32%
46857
SeeingDay
49%21%29%23%11%
5827
Night
25%17%39%31%3
15664

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
311211325%8%68%
1432
16th to endDay
5%313213347%63%
1803
February1st to 15thDay
211213339%68%
1751
16th to endDay
4112313347%65%
1579
March1st to 15thDay
12111245%8%69%
1800
16th to endDay
111112349%71%
2204
April1st to 15thDay
1112212236%74%
2149
16th to endDay
112235%80%
2160
May1st to 15thDay
1212484%
2307
16th to endDay
111111125%80%
2429
June1st to 15thDay
1112485%
2456
16th to endDay
11289%
2520
July1st to 15thDay
111121223478%
2520
16th to endDay
212212236%74%
2515
August1st to 15thDay
1111111286%
2160
16th to endDay
1112485%
2292
September1st to 15thDay
111122482%
2121
16th to endDay
112388%
1871
October1st to 15thDay
11111122479%
1807
16th to endDay
121112225%78%
1697
November1st to 15thDay
111112235%79%
1584
16th to endDay
2112348%73%
1620
December1st to 15thDay
111232335%9%65%
1620
16th to endDay
3212223448%63%
1605
January1st to 15thNight
1212312347%68%
2506
16th to endNight
4213212236%68%
2415
February1st to 15thNight
1213212336%69%
2101
16th to endNight
5%12113447%67%
1895
March1st to 15thNight
11221235%8%71%
2160
16th to endNight
1111112248%73%
2016
April1st to 15thNight
111211233477%
1799
16th to endNight
211225%81%
1800
May1st to 15thNight
11136%83%
1643
16th to endNight
1121484%
1684
June1st to 15thNight
1126%85%
1500
16th to endNight
11291%
1440
July1st to 15thNight
11111132479%
1440
16th to endNight
1111333477%
1649
August1st to 15thNight
11121485%
1800
16th to endNight
1112287%
1910
September1st to 15thNight
111222482%
1839
16th to endNight
111389%
1881
October1st to 15thNight
111224479%
1820
16th to endNight
1111135%82%
2175
November1st to 15thNight
11112235%78%
2275
16th to endNight
21111237%76%
2340
December1st to 15thNight
2212212347%68%
2340
16th to endNight
4212213347%66%
2613

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
15%210%29%31%10%
1432
16th to endDay
22%27%24%27%14%
1803
February1st to 15thDay
15%38%24%30%17%
1751
16th to endDay
19%29%24%31%12%
1579
March1st to 15thDay
12%29%24%30%20%
1800
16th to endDay
11%210%24%31%19%
2204
April1st to 15thDay
12%26%21%35%22%
2149
16th to endDay
7%16%19%34%29%
2160
May1st to 15thDay
6%1317%32%38%
2307
16th to endDay
9%1214%37%34%
2432
June1st to 15thDay
5%1210%23%55%
2456
16th to endDay
5%412%76%
2520
July1st to 15thDay
10%126%14%64%
2371
16th to endDay
13%1310%20%51%
2359
August1st to 15thDay
7%6%18%66%
2146
16th to endDay
5%11424%62%
2292
September1st to 15thDay
8%127%20%59%
2121
16th to endDay
47%32%53%
1871
October1st to 15thDay
11%1313%35%35%
1807
16th to endDay
11%1313%32%38%
1697
November1st to 15thDay
9%15%21%40%21%
1584
16th to endDay
11%28%22%34%20%
1620
December1st to 15thDay
16%411%26%30%10%
1620
16th to endDay
20%5%13%28%21%11%
1605
January1st to 15thNight
16%29%26%31%13%
2506
16th to endNight
18%27%23%27%20%
2415
February1st to 15thNight
17%29%21%27%21%
2112
16th to endNight
16%36%26%32%13%
1895
March1st to 15thNight
12%28%23%31%22%
2160
16th to endNight
10%28%29%31%16%
2016
April1st to 15thNight
12%26%25%35%18%
1799
16th to endNight
8%1424%39%21%
1800
May1st to 15thNight
5%1220%38%31%
1644
16th to endNight
5%1418%39%29%
1685
June1st to 15thNight
41313%27%50%
1500
16th to endNight
36%15%72%
1440
July1st to 15thNight
9%116%15%66%
1360
16th to endNight
11%238%22%51%
1542
August1st to 15thNight
5%117%20%62%
1790
16th to endNight
6%15%28%58%
1910
September1st to 15thNight
8%118%25%54%
1839
16th to endNight
317%34%52%
1881
October1st to 15thNight
9%1411%36%36%
1820
16th to endNight
7%1413%31%41%
2175
November1st to 15thNight
10%1419%36%26%
2275
16th to endNight
10%26%23%28%28%
2340
December1st to 15thNight
16%312%23%30%14%
2340
16th to endNight
18%5%11%26%24%13%
2613

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
15%13%11%31%20%8%
60
16th to endDay
13%9%18%24%18%15%
239
February1st to 15thDay
6%10%18%27%25%10%
266
16th to endDay
10%15%23%25%19%5%
238
March1st to 15thDay
6%15%21%22%22%11%
270
16th to endDay
5%15%27%26%18%5%
288
April1st to 15thDay
10%19%27%19%16%5%
269
16th to endDay
5%18%32%27%11%4
270
May1st to 15thDay
312%32%26%19%6%
288
16th to endDay
413%22%26%23%9%
330
June1st to 15thDay
38%28%27%21%9%
315
16th to endDay
16%24%27%24%16%
315
July1st to 15thDay
2316%32%24%20%
305
16th to endDay
1213%37%26%18%
327
August1st to 15thDay
3220%39%20%13%
315
16th to endDay
212%34%30%18%
332
September1st to 15thDay
2319%33%29%12%
315
16th to endDay
26%12%30%34%14%
276
October1st to 15thDay
5%8%23%27%25%8%
255
16th to endDay
38%14%30%29%13%
209
November1st to 15thDay
25%11%22%27%31%
90
16th to endDay
25%15%38%26%11%
90
December1st to 15thDay
1215%47%24%8%
90
16th to endDay
8%5%12%42%26%5%
75
January1st to 15thNight
2415%43%30%4
720
16th to endNight
6%319%41%26%2
768
February1st to 15thNight
25%18%42%27%3
704
16th to endNight
5%8%20%40%21%2
632
March1st to 15thNight
19%22%40%22%3
720
16th to endNight
110%26%36%22%1
768
April1st to 15thNight
213%27%33%21%2
719
16th to endNight
110%25%38%21%3
720
May1st to 15thNight
17%28%38%21%2
564
16th to endNight
19%26%37%23%
563
June1st to 15thNight
5%25%42%24%1
420
16th to endNight
1117%54%23%1
360
July1st to 15thNight
26%45%42%3
340
16th to endNight
1445%43%3
513
August1st to 15thNight
11%41%41%4
717
16th to endNight
18%32%45%10%
764
September1st to 15thNight
10%32%47%7%
720
16th to endNight
212%32%45%6%
680
October1st to 15thNight
1317%38%34%3
660
16th to endNight
1314%34%41%4
704
November1st to 15thNight
1411%39%38%4
700
16th to endNight
2214%38%36%4
720
December1st to 15thNight
36%13%45%28%3
720
16th to endNight
5%5%20%41%24%2
768
Page generated at 2017-09-22 04:35:30. Version ac04

Copyright 2017 A. Danko


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