Spodue Lookout
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Spodue Lookout clear sky chart from 2005-11-05 to 2018-02-13.

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
56%
15459
20%
48806
19%
15432
59%
15432
29%
29821

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
45%
776
12%
2716
12%
776
48%
776
18%
1881
January16th to endNight
50%
832
19%
2779
21%
832
51%
832
21%
1865
February1st to 15thNight
48%
746
12%
2444
12%
745
51%
745
19%
1693
February16th to endNight
44%
632
14%
1931
14%
632
47%
632
19%
1369
March1st to 15thNight
41%
720
10%
2079
9%
720
42%
720
17%
1558
March16th to endNight
35%
768
13%
2049
9%
768
37%
768
19%
1517
April1st to 15thNight
40%
719
13%
1799
7%
719
42%
719
21%
1330
April16th to endNight
51%
716
18%
1796
9%
716
54%
716
34%
1147
May1st to 15thNight
57%
390
20%
1470
16%
390
64%
390
33%
760
May16th to endNight
56%
375
16%
1496
17%
374
62%
374
24%
858
June1st to 15thNight
62%
360
17%
1440
23%
360
67%
360
27%
775
June16th to endNight
72%
360
26%
1440
39%
360
76%
360
47%
590
July1st to 15thNight
84%
340
26%
1360
37%
340
88%
340
57%
502
July16th to endNight
85%
376
36%
1416
47%
354
89%
354
62%
492
August1st to 15thNight
89%
538
34%
1611
30%
535
90%
535
62%
723
August16th to endNight
82%
735
41%
1881
27%
735
83%
735
73%
872
September1st to 15thNight
84%
720
40%
1800
24%
720
87%
720
75%
845
September16th to endNight
72%
716
35%
1953
29%
716
75%
716
52%
1005
October1st to 15thNight
64%
720
24%
2160
22%
720
70%
720
42%
1163
October16th to endNight
60%
768
24%
2337
25%
768
63%
768
31%
1425
November1st to 15thNight
48%
760
16%
2477
16%
760
50%
760
21%
1678
November16th to endNight
45%
780
11%
2730
11%
780
47%
780
18%
1869
December1st to 15thNight
50%
780
15%
2730
16%
780
52%
780
21%
1780
December16th to endNight
39%
832
14%
2912
14%
832
41%
832
14%
2124

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
10%8%24423346%50%
49250
Night
11%8%24323346%47%
48979
TransparencyDay
35%410%19%19%9%
48922
Night
36%5%12%20%16%7%
48807
SeeingDay
15%12%22%25%17%7%
6102
Night
14%6%16%33%24%4
15470

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
16%12%45%435%347%31%
1552
16th to endDay
17%12%35%422335%38%
1794
February1st to 15thDay
14%14%35%42436%7%33%
1685
16th to endDay
12%17%6%6%6%23346%29%
1542
March1st to 15thDay
18%16%5%5%5%33347%25%
1879
16th to endDay
16%16%45%5%3445%6%28%
2173
April1st to 15thDay
14%16%5%7%6%34336%28%
2149
16th to endDay
9%10%26%423447%44%
2163
May1st to 15thDay
8%7%2442345%6%51%
2478
16th to endDay
12%10%35%5%24346%39%
2615
June1st to 15thDay
10%5%24424437%50%
2520
16th to endDay
6%312322235%68%
2520
July1st to 15thDay
212211235%75%
2520
16th to endDay
11121122479%
2654
August1st to 15thDay
212312345%72%
2340
16th to endDay
2111113481%
2320
September1st to 15thDay
11221223476%
2160
16th to endDay
5%5%13312345%61%
2006
October1st to 15thDay
10%6%24322347%52%
1800
16th to endDay
14%8%24322337%47%
1887
November1st to 15thDay
18%9%26%31345%7%37%
1709
16th to endDay
16%12%46%43345%7%31%
1560
December1st to 15thDay
18%11%24333347%37%
1560
16th to endDay
22%15%36%5%3333427%
1664
January1st to 15thNight
14%12%345%35%45%7%33%
2716
16th to endNight
15%14%34324346%38%
2779
February1st to 15thNight
16%10%35%43445%6%34%
2432
16th to endNight
12%14%46%4335%36%35%
1931
March1st to 15thNight
17%13%45%425%45%6%30%
2079
16th to endNight
16%13%46%423448%30%
2049
April1st to 15thNight
12%11%47%5%35%446%33%
1799
16th to endNight
9%8%2432345%7%49%
1796
May1st to 15thNight
8%41231445%7%55%
1470
16th to endNight
7%6%25%43445%7%46%
1496
June1st to 15thNight
9%423324348%52%
1440
16th to endNight
5%212212145%70%
1440
July1st to 15thNight
122113346%72%
1440
16th to endNight
11121122480%
1512
August1st to 15thNight
11111335%5%73%
1620
16th to endNight
11121212380%
1881
September1st to 15thNight
1111124478%
1800
16th to endNight
5%412222246%65%
1953
October1st to 15thNight
6%413313346%58%
2160
16th to endNight
11%6%2443445%6%47%
2337
November1st to 15thNight
16%9%235%345%5%7%35%
2477
16th to endNight
18%11%35%324347%35%
2730
December1st to 15thNight
18%10%24423347%38%
2730
16th to endNight
18%16%46%423445%29%
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
51%6%13%16%8%1
1552
16th to endDay
48%5%12%17%9%6%
1794
February1st to 15thDay
47%7%15%18%10%1
1685
16th to endDay
54%6%14%15%6%1
1542
March1st to 15thDay
58%5%12%14%8%
1879
16th to endDay
54%7%15%12%8%1
2173
April1st to 15thDay
56%5%10%19%7%
2149
16th to endDay
39%6%16%23%12%2
2163
May1st to 15thDay
33%6%11%26%19%3
2478
16th to endDay
46%5%11%21%13%2
2619
June1st to 15thDay
34%5%10%21%23%4
2520
16th to endDay
20%36%28%30%10%
2520
July1st to 15thDay
13%26%22%28%25%
2371
16th to endDay
10%2413%30%37%
2487
August1st to 15thDay
13%26%18%33%24%
2324
16th to endDay
9%1417%41%25%
2320
September1st to 15thDay
11%25%16%35%28%
2160
16th to endDay
23%5%11%21%23%14%
2006
October1st to 15thDay
30%412%21%20%9%
1800
16th to endDay
38%5%11%20%19%4
1887
November1st to 15thDay
45%6%16%17%12%2
1709
16th to endDay
50%6%13%14%11%3
1560
December1st to 15thDay
46%6%12%22%10%1
1560
16th to endDay
60%5%8%16%8%1
1664
January1st to 15thNight
49%7%14%15%11%1
2716
16th to endNight
47%5%10%18%10%7%
2779
February1st to 15thNight
48%7%15%16%9%2
2444
16th to endNight
48%8%14%19%8%1
1931
March1st to 15thNight
54%7%12%14%10%1
2079
16th to endNight
51%7%15%17%7%1
2049
April1st to 15thNight
49%7%14%18%9%
1799
16th to endNight
34%6%19%26%10%3
1796
May1st to 15thNight
27%6%14%30%17%4
1471
16th to endNight
35%7%15%28%10%2
1496
June1st to 15thNight
32%6%12%26%18%4
1440
16th to endNight
17%48%38%25%5%
1440
July1st to 15thNight
12%28%25%29%21%
1360
16th to endNight
10%25%12%33%34%
1416
August1st to 15thNight
12%48%23%30%20%
1611
16th to endNight
10%1421%36%25%
1881
September1st to 15thNight
8%2420%34%29%
1800
16th to endNight
20%310%24%23%17%
1953
October1st to 15thNight
25%412%25%22%9%
2160
16th to endNight
34%6%13%19%18%6%
2337
November1st to 15thNight
45%7%13%19%11%2
2477
16th to endNight
48%6%13%15%11%4
2730
December1st to 15thNight
44%6%12%21%13%2
2730
16th to endNight
55%6%9%16%9%1
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
34%6%21%17%10%10%
90
16th to endDay
28%12%18%19%15%6%
226
February1st to 15thDay
22%12%24%20%17%1
273
16th to endDay
28%15%23%22%9%1
232
March1st to 15thDay
29%22%21%16%10%
270
16th to endDay
27%22%27%15%6%1
288
April1st to 15thDay
23%22%19%18%11%4
269
16th to endDay
16%24%29%15%10%3
270
May1st to 15thDay
16%17%27%23%10%4
288
16th to endDay
21%10%19%24%15%9%
330
June1st to 15thDay
10%14%28%23%17%5%
315
16th to endDay
6%11%22%29%16%13%
315
July1st to 15thDay
6%6%20%34%22%9%
305
16th to endDay
2324%37%22%10%
327
August1st to 15thDay
35%20%34%23%13%
315
16th to endDay
45%19%27%27%15%
332
September1st to 15thDay
2325%31%23%13%
315
16th to endDay
8%8%23%29%26%3
315
October1st to 15thDay
15%14%23%22%20%3
315
16th to endDay
18%11%21%21%17%8%
303
November1st to 15thDay
23%6%20%35%11%3
133
16th to endDay
26%15%25%18%10%3
90
December1st to 15thDay
32%10%12%20%8%16%
90
16th to endDay
26%5%13%28%22%4
96
January1st to 15thNight
19%6%19%30%18%5%
780
16th to endNight
21%7%15%29%20%6%
832
February1st to 15thNight
19%6%18%34%19%1
752
16th to endNight
18%9%17%34%17%2
632
March1st to 15thNight
22%11%19%24%18%3
720
16th to endNight
22%11%24%25%14%1
768
April1st to 15thNight
16%11%24%29%15%3
719
16th to endNight
13%9%22%29%21%4
716
May1st to 15thNight
10%324%35%24%1
391
16th to endNight
9%5%19%35%26%4
375
June1st to 15thNight
9%318%42%23%1
360
16th to endNight
6%215%44%31%
360
July1st to 15thNight
27%46%40%2
340
16th to endNight
28%52%35%
376
August1st to 15thNight
2440%47%5%
538
16th to endNight
2111%40%39%4
735
September1st to 15thNight
111%33%44%8%
720
16th to endNight
6%313%34%33%7%
716
October1st to 15thNight
7%5%17%37%27%4
720
16th to endNight
13%5%13%31%27%8%
768
November1st to 15thNight
20%5%18%36%14%4
760
16th to endNight
22%9%16%27%17%5%
780
December1st to 15thNight
22%5%15%30%20%5%
780
16th to endNight
26%9%18%30%12%2
832
Page generated at 2018-02-13 17:46:00. Version ac04

Copyright 2018 A. Danko


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