Hensley Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hensley Lake 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
73%
15426
31%
46915
29%
15390
76%
15390
50%
23018

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
67%
717
21%
2479
24%
716
68%
716
33%
1379
January16th to endNight
66%
768
25%
2496
28%
768
67%
768
31%
1472
February1st to 15thNight
68%
698
25%
2182
28%
698
70%
698
37%
1225
February16th to endNight
64%
632
26%
1895
27%
632
66%
632
36%
1095
March1st to 15thNight
64%
720
20%
2112
21%
720
66%
720
40%
1188
March16th to endNight
64%
768
26%
2019
20%
768
68%
768
48%
1133
April1st to 15thNight
57%
719
27%
1799
14%
719
63%
719
46%
1035
April16th to endNight
62%
720
29%
1800
13%
720
67%
720
57%
945
May1st to 15thNight
68%
634
31%
1714
19%
634
73%
634
63%
805
May16th to endNight
64%
409
33%
1531
28%
408
74%
408
53%
607
June1st to 15thNight
67%
360
33%
1440
33%
360
79%
360
59%
507
June16th to endNight
83%
360
40%
1440
48%
360
88%
360
82%
414
July1st to 15thNight
90%
340
37%
1360
45%
340
92%
340
74%
417
July16th to endNight
89%
485
41%
1516
39%
454
91%
454
68%
589
August1st to 15thNight
88%
660
38%
1734
26%
657
89%
657
80%
744
August16th to endNight
92%
764
46%
1910
29%
764
92%
764
86%
838
September1st to 15thNight
90%
720
44%
1800
31%
720
93%
720
83%
796
September16th to endNight
84%
680
46%
1845
40%
680
88%
680
77%
786
October1st to 15thNight
80%
660
35%
1947
35%
660
84%
660
60%
878
October16th to endNight
81%
704
40%
2112
44%
704
83%
704
59%
960
November1st to 15thNight
80%
700
33%
2272
37%
700
81%
700
52%
1050
November16th to endNight
75%
720
29%
2340
32%
720
77%
720
43%
1188
December1st to 15thNight
69%
720
24%
2484
27%
720
71%
720
32%
1400
December16th to endNight
61%
768
23%
2688
25%
768
64%
768
29%
1567

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
6%212212335%67%
47948
Night
8%212212235%66%
47102
TransparencyDay
20%28%20%25%23%
47629
Night
21%29%21%25%20%
46921
SeeingDay
8%417%34%25%9%
5886
Night
8%110%36%33%8%
15436

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
12%4235%24346%50%
1459
16th to endDay
17%423424346%44%
1728
February1st to 15thDay
14%5%2332445%5%48%
1673
16th to endDay
18%424323346%46%
1579
March1st to 15thDay
12%4234246%5%9%46%
1845
16th to endDay
11%4133135%5%7%51%
2205
April1st to 15thDay
11%423313245%56%
2149
16th to endDay
7%212223337%63%
2160
May1st to 15thDay
2212212135%73%
2235
16th to endDay
412212346%69%
2579
June1st to 15thDay
22111122477%
2520
16th to endDay
1111288%
2520
July1st to 15thDay
1122484%
2520
16th to endDay
11111223381%
2546
August1st to 15thDay
1111288%
2217
16th to endDay
1111111385%
2292
September1st to 15thDay
111112385%
2160
16th to endDay
11122482%
1907
October1st to 15thDay
4111322345%69%
1680
16th to endDay
5%112212235%70%
1760
November1st to 15thDay
8%312423425%61%
1585
16th to endDay
10%323324335%56%
1620
December1st to 15thDay
15%5%23435%335%47%
1473
16th to endDay
16%425%424346%44%
1536
January1st to 15thNight
12%424322336%53%
2479
16th to endNight
16%413313437%49%
2496
February1st to 15thNight
13%41321345%7%52%
2176
16th to endNight
18%313222346%51%
1895
March1st to 15thNight
12%32422335%5%55%
2112
16th to endNight
10%313212437%58%
2019
April1st to 15thNight
10%31331335%7%58%
1799
16th to endNight
6%211213325%70%
1800
May1st to 15thNight
3112212235%73%
1714
16th to endNight
413112235%73%
1530
June1st to 15thNight
21111223478%
1440
16th to endNight
1111289%
1440
July1st to 15thNight
11122285%
1440
16th to endNight
21111122380%
1621
August1st to 15thNight
11111286%
1743
16th to endNight
11111486%
1910
September1st to 15thNight
11112386%
1800
16th to endNight
1111122383%
1845
October1st to 15thNight
4211212236%70%
1947
16th to endNight
5%2121235%73%
2112
November1st to 15thNight
7%212212126%68%
2272
16th to endNight
7%213223337%60%
2340
December1st to 15thNight
13%423323346%52%
2484
16th to endNight
19%323323237%47%
2688

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
35%5%14%21%19%4
1459
16th to endDay
41%411%19%15%8%
1728
February1st to 15thDay
36%412%25%16%3
1673
16th to endDay
37%212%30%15%1
1579
March1st to 15thDay
32%5%16%23%17%5%
1845
16th to endDay
30%417%25%18%3
2205
April1st to 15thDay
29%311%28%19%7%
2149
16th to endDay
22%211%26%27%8%
2160
May1st to 15thDay
15%17%25%36%14%
2235
16th to endDay
15%18%30%32%12%
2583
June1st to 15thDay
12%28%18%30%27%
2520
16th to endDay
5%28%32%50%
2520
July1st to 15thDay
5%115%21%63%
2371
16th to endDay
10%128%21%55%
2388
August1st to 15thDay
6%8%27%55%
2201
16th to endDay
7%18%34%48%
2292
September1st to 15thDay
7%1211%31%45%
2160
16th to endDay
8%1221%39%27%
1907
October1st to 15thDay
15%27%24%28%21%
1680
16th to endDay
17%16%27%28%17%
1760
November1st to 15thDay
26%212%26%26%5%
1585
16th to endDay
30%312%25%24%3
1620
December1st to 15thDay
39%5%9%22%19%3
1473
16th to endDay
40%5%15%21%15%3
1536
January1st to 15thNight
33%312%25%20%5%
2479
16th to endNight
35%411%17%18%11%
2496
February1st to 15thNight
31%313%27%18%5%
2187
16th to endNight
33%213%30%16%2
1895
March1st to 15thNight
30%217%21%22%5%
2112
16th to endNight
25%316%27%21%5%
2019
April1st to 15thNight
26%215%30%18%6%
1799
16th to endNight
18%214%26%30%7%
1800
May1st to 15thNight
13%28%23%35%16%
1715
16th to endNight
15%28%27%33%12%
1531
June1st to 15thNight
11%17%23%27%27%
1440
16th to endNight
4210%25%56%
1440
July1st to 15thNight
6%1422%63%
1360
16th to endNight
10%117%20%57%
1516
August1st to 15thNight
7%18%27%55%
1734
16th to endNight
418%32%51%
1910
September1st to 15thNight
6%129%30%49%
1800
16th to endNight
8%1117%41%30%
1845
October1st to 15thNight
15%28%24%27%21%
1947
16th to endNight
16%2425%31%20%
2112
November1st to 15thNight
20%111%27%28%9%
2272
16th to endNight
25%311%26%25%7%
2340
December1st to 15thNight
33%412%23%20%5%
2484
16th to endNight
37%314%23%15%4
2688

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
27%117%31%13%9%
87
16th to endDay
22%111%28%23%13%
256
February1st to 15thDay
20%411%25%20%17%
253
16th to endDay
19%6%17%28%19%7%
238
March1st to 15thDay
12%6%21%25%22%11%
270
16th to endDay
17%8%22%28%18%5%
288
April1st to 15thDay
16%13%26%25%13%4
269
16th to endDay
9%14%25%31%13%5%
270
May1st to 15thDay
5%8%26%36%16%6%
288
16th to endDay
48%22%33%24%6%
330
June1st to 15thDay
25%27%35%23%4
315
16th to endDay
213%39%31%12%
315
July1st to 15thDay
8%36%40%13%
305
16th to endDay
18%40%37%11%
327
August1st to 15thDay
4113%45%25%9%
315
16th to endDay
10%39%31%16%
332
September1st to 15thDay
212%46%27%10%
315
16th to endDay
3418%35%29%7%
276
October1st to 15thDay
45%22%35%25%5%
255
16th to endDay
8%416%32%28%9%
272
November1st to 15thDay
12%1313%35%35%
91
16th to endDay
8%418%31%31%5%
90
December1st to 15thDay
16%115%44%21%
65
16th to endDay
20%19%28%29%10%
64
January1st to 15thNight
14%17%33%29%13%
720
16th to endNight
18%17%32%29%9%
768
February1st to 15thNight
15%18%33%29%10%
704
16th to endNight
18%19%35%26%7%
632
March1st to 15thNight
12%212%35%29%7%
720
16th to endNight
11%216%36%28%4
768
April1st to 15thNight
10%5%21%34%25%3
719
16th to endNight
6%422%34%25%6%
720
May1st to 15thNight
3320%44%23%4
635
16th to endNight
5%323%38%28%
409
June1st to 15thNight
3323%45%23%
360
16th to endNight
114%54%29%
360
July1st to 15thNight
5%49%43%1
340
16th to endNight
21332%52%8%
485
August1st to 15thNight
26%40%43%7%
660
16th to endNight
5%34%51%8%
764
September1st to 15thNight
15%32%49%11%
720
16th to endNight
210%33%41%12%
680
October1st to 15thNight
5%18%35%37%11%
660
16th to endNight
7%16%31%35%17%
704
November1st to 15thNight
9%15%32%36%14%
700
16th to endNight
7%19%36%32%13%
720
December1st to 15thNight
15%17%37%29%8%
720
16th to endNight
20%18%39%23%5%
768
Page generated at 2017-09-22 04:35:33. Version ac04

Copyright 2017 A. Danko


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