Lake Pleasant
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Pleasant clear sky chart from 2005-11-05 to 2017-04-02.

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
77%
15144
37%
45346
33%
15104
81%
15104
56%
21147

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%
719
34%
2327
33%
716
76%
716
47%
1109
January16th to endNight
63%
768
37%
2496
34%
768
73%
768
43%
1251
February1st to 15thNight
72%
699
37%
2166
33%
698
81%
698
54%
1012
February16th to endNight
68%
632
35%
1895
36%
632
73%
632
47%
979
March1st to 15thNight
70%
720
40%
1987
33%
720
77%
720
58%
971
March16th to endNight
76%
768
40%
2112
31%
768
82%
768
64%
979
April1st to 15thNight
69%
666
34%
1833
23%
666
76%
666
55%
905
April16th to endNight
71%
498
44%
1529
34%
498
80%
498
74%
595
May1st to 15thNight
77%
494
41%
1484
34%
494
82%
494
67%
618
May16th to endNight
80%
513
38%
1540
30%
513
83%
513
72%
629
June1st to 15thNight
85%
495
37%
1485
33%
495
86%
495
75%
589
June16th to endNight
92%
495
33%
1485
31%
495
92%
495
78%
587
July1st to 15thNight
86%
465
28%
1395
25%
465
86%
465
53%
679
July16th to endNight
85%
522
28%
1467
24%
489
85%
489
46%
781
August1st to 15thNight
88%
494
33%
1476
28%
491
89%
491
51%
733
August16th to endNight
84%
608
33%
1713
29%
608
84%
608
47%
931
September1st to 15thNight
82%
660
33%
1815
29%
660
84%
660
52%
955
September16th to endNight
85%
656
42%
1815
34%
656
89%
656
70%
802
October1st to 15thNight
79%
660
42%
1878
35%
660
83%
660
64%
850
October16th to endNight
82%
704
44%
2112
38%
704
88%
704
66%
897
November1st to 15thNight
82%
700
42%
2160
39%
700
86%
700
65%
900
November16th to endNight
76%
720
40%
2340
40%
720
82%
720
56%
1028
December1st to 15thNight
72%
720
37%
2340
36%
720
78%
720
48%
1097
December16th to endNight
67%
768
36%
2496
35%
768
72%
768
41%
1270

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
3212212346%70%
45769
Night
3212213345%69%
45545
TransparencyDay
16%2411%25%39%
45464
Night
17%2410%23%40%
45351
SeeingDay
4420%37%26%6%
4819
Night
4111%39%37%5%
15153

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
5%21331234467%
1611
16th to endDay
8%213221236%66%
1728
February1st to 15thDay
3213212335%67%
1692
16th to endDay
7%313312346%62%
1579
March1st to 15thDay
5%112213236%68%
1971
16th to endDay
2112213225%72%
2112
April1st to 15thDay
3112113346%70%
1817
16th to endDay
111112235%78%
2098
May1st to 15thDay
11112235%79%
2136
16th to endDay
21111111480%
2221
June1st to 15thDay
1111112482%
2145
16th to endDay
111212383%
2145
July1st to 15thDay
211332346%7%62%
2145
16th to endDay
4323436%6%7%10%47%
2285
August1st to 15thDay
321333445%10%57%
2145
16th to endDay
311232345%7%62%
2134
September1st to 15thDay
4212223346%65%
1815
16th to endDay
21111122381%
1815
October1st to 15thDay
21121222477%
1751
16th to endDay
1111223478%
1760
November1st to 15thDay
1222345%75%
1696
16th to endDay
5%12212235%73%
1620
December1st to 15thDay
5%31322335%6%62%
1620
16th to endDay
7%313322346%60%
1728
January1st to 15thNight
5%312213335%66%
2327
16th to endNight
8%31332313464%
2496
February1st to 15thNight
4312212335%68%
2158
16th to endNight
6%212224436%62%
1895
March1st to 15thNight
412311335%70%
1987
16th to endNight
311212236%73%
2112
April1st to 15thNight
312314345%68%
1833
16th to endNight
211113383%
1529
May1st to 15thNight
111112347%75%
1484
16th to endNight
211111383%
1540
June1st to 15thNight
1111122383%
1485
16th to endNight
111112384%
1485
July1st to 15thNight
11124235%6%10%60%
1485
16th to endNight
2213426%5%7%10%52%
1575
August1st to 15thNight
12123245%6%10%59%
1485
16th to endNight
123425%5%6%8%58%
1713
September1st to 15thNight
22123246%6%7%60%
1815
16th to endNight
11111233479%
1815
October1st to 15thNight
312112225%74%
1878
16th to endNight
11121223477%
2112
November1st to 15thNight
211212335%75%
2160
16th to endNight
5%1122223473%
2340
December1st to 15thNight
6%212213346%65%
2340
16th to endNight
7%323323345%60%
2496

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
21%2413%27%31%
1612
16th to endDay
21%1417%25%29%
1728
February1st to 15thDay
19%26%14%27%29%
1692
16th to endDay
23%2317%28%24%
1579
March1st to 15thDay
18%128%31%37%
1971
16th to endDay
16%2310%32%34%
2112
April1st to 15thDay
15%139%31%37%
1817
16th to endDay
10%127%24%53%
2098
May1st to 15thDay
9%37%25%53%
2136
16th to endDay
11%116%24%55%
2224
June1st to 15thDay
8%1415%68%
2145
16th to endDay
7%12312%72%
2145
July1st to 15thDay
19%410%13%18%33%
2006
16th to endDay
27%7%12%20%20%13%
2130
August1st to 15thDay
21%48%16%20%28%
2130
16th to endDay
19%5%7%17%29%21%
2134
September1st to 15thDay
19%38%12%22%33%
1815
16th to endDay
10%115%26%53%
1815
October1st to 15thDay
12%2310%26%45%
1751
16th to endDay
10%147%26%48%
1760
November1st to 15thDay
11%2311%32%39%
1696
16th to endDay
15%1211%25%43%
1620
December1st to 15thDay
22%36%17%25%24%
1620
16th to endDay
25%35%19%28%17%
1728
January1st to 15thNight
22%2411%25%34%
2327
16th to endNight
26%1311%25%31%
2496
February1st to 15thNight
18%26%13%24%34%
2169
16th to endNight
24%3411%27%29%
1895
March1st to 15thNight
17%238%25%43%
1987
16th to endNight
14%149%31%38%
2112
April1st to 15thNight
18%238%28%38%
1833
16th to endNight
8%137%23%56%
1529
May1st to 15thNight
10%136%26%51%
1485
16th to endNight
10%15%21%60%
1541
June1st to 15thNight
8%12414%69%
1485
16th to endNight
7%147%77%
1485
July1st to 15thNight
18%410%14%15%36%
1395
16th to endNight
21%6%12%18%23%16%
1467
August1st to 15thNight
17%5%10%18%16%30%
1476
16th to endNight
21%6%7%15%21%27%
1713
September1st to 15thNight
19%5%8%14%20%30%
1815
16th to endNight
10%125%22%57%
1815
October1st to 15thNight
14%1210%24%45%
1878
16th to endNight
11%238%18%55%
2112
November1st to 15thNight
12%1210%29%43%
2160
16th to endNight
16%248%23%45%
2340
December1st to 15thNight
21%25%13%26%30%
2340
16th to endNight
26%26%16%28%19%
2496

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
26%120%35%15%1
90
16th to endDay
9%314%33%27%12%
96
February1st to 15thDay
3323%40%27%2
207
16th to endDay
8%7%34%33%14%1
238
March1st to 15thDay
6%8%21%37%21%4
270
16th to endDay
39%32%31%19%3
288
April1st to 15thDay
8%12%28%31%14%3
214
16th to endDay
415%40%27%9%2
210
May1st to 15thDay
310%28%37%16%2
228
16th to endDay
3430%34%22%4
266
June1st to 15thDay
1332%37%19%5%
255
16th to endDay
116%44%29%7%
255
July1st to 15thDay
110%49%31%6%
245
16th to endDay
2433%41%16%
271
August1st to 15thDay
25%35%40%16%
255
16th to endDay
1439%46%8%
268
September1st to 15thDay
6%112%40%33%4
255
16th to endDay
5%217%41%25%7%
255
October1st to 15thDay
4221%34%30%5%
191
16th to endDay
2111%33%46%5%
96
November1st to 15thDay
2313%40%33%7%
90
16th to endDay
7%221%41%26%1
90
December1st to 15thDay
3114%33%41%6%
90
16th to endDay
10%8%20%38%18%3
96
January1st to 15thNight
7%214%45%25%4
720
16th to endNight
9%217%40%26%3
768
February1st to 15thNight
6%214%45%27%3
704
16th to endNight
7%116%48%22%3
632
March1st to 15thNight
5%117%41%28%4
720
16th to endNight
3313%42%32%4
768
April1st to 15thNight
3417%46%24%3
666
16th to endNight
1221%43%26%3
498
May1st to 15thNight
1314%46%31%2
495
16th to endNight
2112%40%39%3
515
June1st to 15thNight
1110%45%39%2
495
16th to endNight
1340%48%6%
495
July1st to 15thNight
2428%58%6%
465
16th to endNight
1319%65%9%
522
August1st to 15thNight
1220%62%11%
494
16th to endNight
3221%62%10%
608
September1st to 15thNight
36%27%54%7%
660
16th to endNight
217%35%45%7%
656
October1st to 15thNight
3110%40%39%4
660
16th to endNight
29%39%38%9%
704
November1st to 15thNight
319%42%37%5%
700
16th to endNight
5%110%41%34%5%
720
December1st to 15thNight
7%212%41%33%2
720
16th to endNight
9%213%44%26%4
768
Page generated at 2017-04-02 22:35:07. Version ac04

Copyright 2017 A. Danko


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