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Landers
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Landers clear sky chart from 2005-11-05 to 2019-09-17.

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
74%
18816
40%
54886
31%
18777
82%
18777
66%
23540

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
68%
838
35%
2717
29%
836
78%
836
48%
1251
January16th to endNight
63%
896
39%
2758
30%
896
76%
896
52%
1280
February1st to 15thNight
64%
819
40%
2468
31%
818
78%
818
58%
1106
February16th to endNight
60%
736
38%
2207
34%
736
71%
736
55%
1016
March1st to 15thNight
62%
840
37%
2499
30%
840
75%
840
58%
1108
March16th to endNight
66%
896
39%
2416
26%
896
77%
896
63%
1119
April1st to 15thNight
56%
839
40%
2099
17%
839
70%
839
62%
1035
April16th to endNight
63%
820
41%
2068
20%
820
73%
820
72%
925
May1st to 15thNight
71%
629
44%
1889
30%
629
78%
629
78%
712
May16th to endNight
67%
657
39%
1973
27%
657
74%
657
76%
759
June1st to 15thNight
81%
630
38%
1890
30%
630
85%
630
82%
699
June16th to endNight
84%
630
36%
1890
31%
630
86%
630
83%
709
July1st to 15thNight
90%
600
34%
1800
31%
600
91%
600
73%
723
July16th to endNight
89%
660
35%
1881
29%
627
89%
627
61%
841
August1st to 15thNight
92%
806
40%
2042
26%
803
93%
803
80%
913
August16th to endNight
93%
892
44%
2230
31%
892
93%
892
81%
1003
September1st to 15thNight
91%
840
43%
2201
34%
840
93%
840
80%
954
September16th to endNight
88%
780
48%
2157
42%
780
92%
780
87%
843
October1st to 15thNight
78%
780
46%
2145
36%
780
86%
780
76%
903
October16th to endNight
82%
832
45%
2519
42%
832
89%
832
73%
991
November1st to 15thNight
78%
820
42%
2665
39%
820
88%
820
69%
1023
November16th to endNight
76%
840
42%
2730
40%
840
84%
840
62%
1114
December1st to 15thNight
69%
840
38%
2730
32%
840
80%
840
52%
1217
December16th to endNight
61%
896
37%
2912
30%
896
74%
896
49%
1296

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%76%
55798
Night
111112235%78%
55085
TransparencyDay
11%25%14%27%39%
55493
Night
10%25%14%29%37%
54891
SeeingDay
310%23%34%21%6%
8528
Night
1316%33%34%9%
18826

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
321221225%6%68%
1881
16th to endDay
1212313346%68%
2168
February1st to 15thDay
1112113347%71%
2051
16th to endDay
112214346%70%
1839
March1st to 15thDay
11111235%7%72%
2120
16th to endDay
12112247%74%
2509
April1st to 15thDay
1111212236%75%
2509
16th to endDay
1111136%82%
2495
May1st to 15thDay
1111123481%
2721
16th to endDay
111222482%
2845
June1st to 15thDay
112485%
2730
16th to endDay
11111288%
2730
July1st to 15thDay
212212245%73%
2730
16th to endDay
21232445%6%66%
2883
August1st to 15thDay
111221224477%
2488
16th to endDay
11112345%76%
2676
September1st to 15thDay
1121223379%
2417
16th to endDay
11111287%
2157
October1st to 15thDay
111222481%
2145
16th to endDay
11113483%
2054
November1st to 15thDay
1111223478%
1854
16th to endDay
111113246%74%
1890
December1st to 15thDay
2212222239%67%
1890
16th to endDay
2212222337%68%
2016
January1st to 15thNight
122223447%67%
2717
16th to endNight
21221235%6%70%
2758
February1st to 15thNight
212212335%73%
2461
16th to endNight
22121246%7%68%
2207
March1st to 15thNight
211212348%71%
2499
16th to endNight
2212246%76%
2416
April1st to 15thNight
11212335%76%
2099
16th to endNight
11226%82%
2068
May1st to 15thNight
2225%84%
1889
16th to endNight
212485%
1972
June1st to 15thNight
113387%
1890
16th to endNight
1111290%
1890
July1st to 15thNight
11112235%79%
1890
16th to endNight
112223345%73%
1989
August1st to 15thNight
1111135%82%
2051
16th to endNight
11135%83%
2230
September1st to 15thNight
11113484%
2201
16th to endNight
11290%
2157
October1st to 15thNight
111225%83%
2145
16th to endNight
111122483%
2519
November1st to 15thNight
112235%80%
2665
16th to endNight
211111235%76%
2730
December1st to 15thNight
222223338%68%
2730
16th to endNight
222212247%70%
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
17%47%19%31%19%
1882
16th to endDay
17%45%21%29%21%
2168
February1st to 15thDay
14%45%17%31%26%
2051
16th to endDay
14%5%7%18%33%19%
1839
March1st to 15thDay
11%35%20%32%25%
2120
16th to endDay
11%26%22%32%23%
2509
April1st to 15thDay
13%25%16%35%27%
2509
16th to endDay
6%1416%34%36%
2495
May1st to 15thDay
8%2411%34%39%
2721
16th to endDay
7%2412%32%40%
2848
June1st to 15thDay
5%128%20%62%
2730
16th to endDay
6%1310%77%
2730
July1st to 15thDay
12%25%9%16%53%
2591
16th to endDay
16%5%7%15%20%34%
2728
August1st to 15thDay
10%239%21%52%
2473
16th to endDay
9%2411%23%47%
2676
September1st to 15thDay
9%348%20%52%
2417
16th to endDay
6%125%27%57%
2157
October1st to 15thDay
9%2310%29%44%
2145
16th to endDay
7%149%29%47%
2054
November1st to 15thDay
11%25%14%33%33%
1854
16th to endDay
11%35%16%32%29%
1890
December1st to 15thDay
17%38%22%26%22%
1890
16th to endDay
18%48%24%26%17%
2016
January1st to 15thNight
17%47%18%27%22%
2717
16th to endNight
15%47%20%26%24%
2758
February1st to 15thNight
14%26%18%29%27%
2472
16th to endNight
14%47%19%31%22%
2207
March1st to 15thNight
12%35%21%31%24%
2499
16th to endNight
10%36%18%38%22%
2416
April1st to 15thNight
11%45%18%33%26%
2099
16th to endNight
6%1314%37%36%
2068
May1st to 15thNight
5%1416%36%35%
1890
16th to endNight
5%1316%36%35%
1973
June1st to 15thNight
4128%20%61%
1890
16th to endNight
4115%12%74%
1890
July1st to 15thNight
8%148%17%58%
1800
16th to endNight
12%45%16%24%36%
1881
August1st to 15thNight
6%239%22%54%
2042
16th to endNight
6%239%28%50%
2230
September1st to 15thNight
6%25%8%20%56%
2201
16th to endNight
315%27%60%
2157
October1st to 15thNight
7%2411%33%41%
2145
16th to endNight
7%148%26%50%
2519
November1st to 15thNight
8%2413%37%33%
2665
16th to endNight
12%25%16%32%30%
2730
December1st to 15thNight
15%47%18%27%25%
2730
16th to endNight
16%310%19%29%20%
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
11%6%22%35%20%3
180
16th to endDay
316%29%31%15%4
344
February1st to 15thDay
414%31%28%15%5%
386
16th to endDay
6%23%28%26%15%
342
March1st to 15thDay
5%21%26%30%14%1
390
16th to endDay
5%15%32%32%12%1
416
April1st to 15thDay
5%21%26%26%15%3
389
16th to endDay
324%28%24%14%4
378
May1st to 15thDay
311%27%36%14%6%
408
16th to endDay
213%30%34%14%4
458
June1st to 15thDay
15%25%36%24%6%
435
16th to endDay
1223%34%25%11%
435
July1st to 15thDay
113%40%31%13%
425
16th to endDay
414%39%28%13%
455
August1st to 15thDay
2118%43%24%10%
419
16th to endDay
13%40%29%15%
460
September1st to 15thDay
1117%47%26%4
435
16th to endDay
27%22%36%28%3
380
October1st to 15thDay
210%27%40%16%1
375
16th to endDay
26%18%31%31%9%
286
November1st to 15thDay
18%18%33%32%5%
180
16th to endDay
29%25%27%29%6%
180
December1st to 15thDay
7%9%20%29%31%2
180
16th to endDay
7%12%18%29%26%5%
192
January1st to 15thNight
2420%37%24%10%
840
16th to endNight
35%23%33%28%6%
896
February1st to 15thNight
25%22%34%26%8%
824
16th to endNight
26%29%34%20%6%
736
March1st to 15thNight
27%25%33%25%6%
840
16th to endNight
17%21%36%26%7%
896
April1st to 15thNight
17%29%30%24%5%
839
16th to endNight
9%23%31%26%7%
820
May1st to 15thNight
1421%38%29%5%
630
16th to endNight
5%24%35%28%4
659
June1st to 15thNight
116%43%35%3
630
16th to endNight
13%40%40%4
630
July1st to 15thNight
1433%51%8%
600
16th to endNight
2333%52%7%
660
August1st to 15thNight
329%50%15%
806
16th to endNight
1221%51%22%
892
September1st to 15thNight
328%50%15%
840
16th to endNight
17%31%44%14%
780
October1st to 15thNight
1116%35%36%7%
780
16th to endNight
211%30%38%16%
832
November1st to 15thNight
116%34%36%10%
820
16th to endNight
3314%31%33%13%
840
December1st to 15thNight
3419%36%28%7%
840
16th to endNight
5%8%20%33%24%7%
896
Page generated at 2019-09-17 18:12:14. Version ac04

Copyright 2019 A. Danko


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