Lake Mead (ASN-LV)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Mead (ASN-LV) clear sky chart from 2005-11-05 to 2018-03-21.

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
63%
16608
38%
49219
27%
16570
74%
16570
50%
22463

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
60%
778
32%
2522
26%
776
70%
776
39%
1197
January16th to endNight
57%
832
37%
2688
29%
832
71%
832
39%
1283
February1st to 15thNight
58%
760
36%
2292
30%
760
68%
760
41%
1119
February16th to endNight
53%
684
37%
2051
29%
684
68%
684
40%
1017
March1st to 15thNight
56%
780
36%
2265
27%
780
69%
780
46%
1083
March16th to endNight
59%
792
38%
2178
24%
792
71%
792
48%
1063
April1st to 15thNight
49%
719
34%
1838
16%
719
60%
719
47%
924
April16th to endNight
53%
615
42%
1695
19%
615
68%
615
54%
757
May1st to 15thNight
57%
539
37%
1619
21%
539
68%
539
52%
692
May16th to endNight
55%
561
35%
1685
20%
561
67%
561
53%
706
June1st to 15thNight
61%
540
33%
1620
22%
540
70%
540
61%
631
June16th to endNight
67%
540
35%
1620
24%
540
77%
540
65%
622
July1st to 15thNight
74%
510
29%
1530
24%
510
77%
510
52%
699
July16th to endNight
68%
564
34%
1593
25%
531
78%
531
47%
766
August1st to 15thNight
74%
554
39%
1626
27%
551
78%
551
57%
726
August16th to endNight
79%
764
42%
1910
25%
764
85%
764
62%
947
September1st to 15thNight
77%
720
38%
1930
28%
720
81%
720
60%
909
September16th to endNight
77%
716
48%
1980
35%
716
87%
716
71%
820
October1st to 15thNight
72%
720
43%
1980
34%
720
79%
720
61%
905
October16th to endNight
70%
768
45%
2353
36%
768
83%
768
59%
974
November1st to 15thNight
68%
760
38%
2470
34%
760
77%
760
52%
1031
November16th to endNight
64%
780
43%
2535
36%
780
77%
780
50%
1052
December1st to 15thNight
60%
780
36%
2535
31%
780
70%
780
41%
1149
December16th to endNight
54%
832
34%
2704
26%
832
67%
832
33%
1391

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
212212346%71%
49625
Night
2212212346%71%
49414
TransparencyDay
14%2415%27%34%
49320
Night
15%2414%27%35%
49220
SeeingDay
313%16%27%27%11%
6260
Night
317%11%32%30%4
16617

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
323324448%62%
1746
16th to endDay
6%213323337%62%
1886
February1st to 15thDay
2113223347%66%
1901
16th to endDay
5%31322335%5%63%
1709
March1st to 15thDay
213212347%70%
2023
16th to endDay
2212213346%67%
2173
April1st to 15thDay
221231235%6%68%
2107
16th to endDay
21121133477%
2262
May1st to 15thDay
122237%76%
2331
16th to endDay
111112235%78%
2429
June1st to 15thDay
11113384%
2340
16th to endDay
1112387%
2340
July1st to 15thDay
2112313346%68%
2340
16th to endDay
31123245%5%9%60%
2467
August1st to 15thDay
21221225%5%73%
2322
16th to endDay
211223347%72%
2292
September1st to 15thDay
111112345%75%
2028
16th to endDay
1111212383%
1980
October1st to 15thDay
211111223476%
1980
16th to endDay
11121213480%
1868
November1st to 15thDay
221112335%73%
1719
16th to endDay
2111213237%72%
1755
December1st to 15thDay
331331345%8%60%
1755
16th to endDay
6%225%32335%10%54%
1872
January1st to 15thNight
3213322446%65%
2522
16th to endNight
5%313213346%64%
2688
February1st to 15thNight
3213323235%67%
2281
16th to endNight
5%312213346%64%
2051
March1st to 15thNight
311221245%8%66%
2265
16th to endNight
2112213346%69%
2178
April1st to 15thNight
2113212236%71%
1838
16th to endNight
112212245%76%
1695
May1st to 15thNight
111212335%76%
1619
16th to endNight
11212336%75%
1684
June1st to 15thNight
111122482%
1620
16th to endNight
1212385%
1620
July1st to 15thNight
11112135%5%7%68%
1620
16th to endNight
211232446%9%61%
1701
August1st to 15thNight
221212335%72%
1635
16th to endNight
111122345%75%
1910
September1st to 15thNight
111111235%7%72%
1930
16th to endNight
11122384%
1980
October1st to 15thNight
21112235%77%
1980
16th to endNight
1121223479%
2353
November1st to 15thNight
1212112235%74%
2470
16th to endNight
2112211136%74%
2535
December1st to 15thNight
421232225%7%66%
2535
16th to endNight
6%412313347%59%
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
22%38%32%28%4
1747
16th to endDay
24%27%30%28%5%
1886
February1st to 15thDay
19%38%23%31%13%
1901
16th to endDay
23%26%21%31%14%
1709
March1st to 15thDay
15%25%18%39%19%
2023
16th to endDay
16%3419%35%19%
2173
April1st to 15thDay
17%2313%31%31%
2107
16th to endDay
11%2313%32%37%
2262
May1st to 15thDay
9%2311%29%43%
2331
16th to endDay
9%136%30%47%
2432
June1st to 15thDay
7%25%16%67%
2340
16th to endDay
6%1210%78%
2340
July1st to 15thDay
15%337%16%52%
2201
16th to endDay
18%46%14%20%35%
2312
August1st to 15thDay
12%2410%24%46%
2307
16th to endDay
12%239%24%46%
2292
September1st to 15thDay
11%3310%23%47%
2028
16th to endDay
8%117%26%54%
1980
October1st to 15thDay
12%2411%28%40%
1980
16th to endDay
10%1314%37%32%
1868
November1st to 15thDay
14%2421%38%17%
1719
16th to endDay
15%25%24%37%14%
1755
December1st to 15thDay
22%411%26%27%8%
1755
16th to endDay
28%411%27%21%6%
1872
January1st to 15thNight
20%35%26%34%9%
2522
16th to endNight
21%25%24%30%14%
2688
February1st to 15thNight
20%36%18%30%21%
2292
16th to endNight
21%2416%35%19%
2051
March1st to 15thNight
17%3415%34%25%
2265
16th to endNight
17%2416%33%26%
2178
April1st to 15thNight
16%2412%32%32%
1838
16th to endNight
11%2211%28%45%
1695
May1st to 15thNight
10%249%26%46%
1620
16th to endNight
11%139%23%50%
1685
June1st to 15thNight
7%12314%69%
1620
16th to endNight
6%1210%77%
1620
July1st to 15thNight
15%238%14%55%
1530
16th to endNight
19%35%12%22%37%
1593
August1st to 15thNight
14%238%19%52%
1626
16th to endNight
13%227%23%51%
1910
September1st to 15thNight
12%3411%18%50%
1930
16th to endNight
7%116%20%63%
1980
October1st to 15thNight
11%229%24%49%
1980
16th to endNight
10%239%24%48%
2353
November1st to 15thNight
13%2216%38%26%
2470
16th to endNight
14%1416%35%27%
2535
December1st to 15thNight
18%26%25%30%15%
2535
16th to endNight
26%39%26%26%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
14%8%12%36%23%4
135
16th to endDay
8%313%31%30%13%
158
February1st to 15thDay
415%14%24%29%11%
326
16th to endDay
6%24%14%27%20%7%
290
March1st to 15thDay
5%18%17%22%26%9%
330
16th to endDay
320%21%24%20%8%
311
April1st to 15thDay
7%25%22%20%15%8%
269
16th to endDay
329%24%24%14%5%
270
May1st to 15thDay
319%25%27%18%7%
288
16th to endDay
117%21%27%23%8%
330
June1st to 15thDay
115%24%26%20%10%
315
16th to endDay
13%14%22%30%19%
315
July1st to 15thDay
17%13%29%29%17%
305
16th to endDay
411%8%31%33%11%
327
August1st to 15thDay
46%18%30%31%9%
315
16th to endDay
36%9%24%34%21%
332
September1st to 15thDay
17%13%29%34%13%
315
16th to endDay
19%15%24%32%17%
315
October1st to 15thDay
111%13%34%22%17%
315
16th to endDay
46%7%28%36%18%
150
November1st to 15thDay
2114%25%45%9%
135
16th to endDay
9%8%36%39%5%
135
December1st to 15thDay
26%14%30%40%5%
135
16th to endDay
9%10%6%36%27%9%
144
January1st to 15thNight
318%10%35%27%4
780
16th to endNight
7%18%11%32%27%3
832
February1st to 15thNight
319%12%39%22%3
764
16th to endNight
6%20%16%34%20%1
684
March1st to 15thNight
320%14%34%24%2
780
16th to endNight
221%12%36%24%1
792
April1st to 15thNight
326%17%29%20%3
719
16th to endNight
224%18%29%21%3
615
May1st to 15thNight
221%15%33%23%2
540
16th to endNight
123%16%31%25%2
563
June1st to 15thNight
20%16%38%22%2
540
16th to endNight
17%12%35%31%3
540
July1st to 15thNight
112%7%34%41%3
510
16th to endNight
316%6%29%41%2
564
August1st to 15thNight
39%7%34%41%2
554
16th to endNight
29%5%24%49%9%
764
September1st to 15thNight
29%5%26%45%9%
720
16th to endNight
19%9%28%42%8%
716
October1st to 15thNight
212%9%36%34%4
720
16th to endNight
112%10%29%39%6%
768
November1st to 15thNight
316%10%31%34%4
760
16th to endNight
318%9%33%29%4
780
December1st to 15thNight
5%20%9%36%26%2
780
16th to endNight
8%21%10%33%22%3
832
Page generated at 2018-03-22 08:34:23. Version ac04

Copyright 2018 A. Danko


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