Lookout Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lookout Point clear sky chart from 2005-11-05 to 2017-09-22.

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
32%
14647
13%
46912
9%
14616
37%
14616
16%
33606

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
18%
720
6%
2506
3%
716
22%
716
6%
2070
January16th to endNight
25%
768
11%
2616
6%
768
31%
768
12%
1972
February1st to 15thNight
20%
703
9%
2287
5%
701
26%
701
11%
1791
February16th to endNight
22%
631
13%
1984
5%
631
31%
631
13%
1496
March1st to 15thNight
22%
720
12%
2064
7%
720
28%
720
14%
1588
March16th to endNight
32%
768
20%
2058
10%
768
39%
768
23%
1408
April1st to 15thNight
27%
718
15%
1796
6%
718
31%
718
20%
1332
April16th to endNight
30%
623
17%
1703
9%
623
36%
623
22%
1187
May1st to 15thNight
34%
360
17%
1440
18%
360
43%
360
17%
948
May16th to endNight
37%
375
13%
1497
11%
374
48%
374
20%
935
June1st to 15thNight
39%
360
9%
1440
9%
360
47%
360
17%
930
June16th to endNight
47%
360
9%
1440
13%
360
51%
360
20%
919
July1st to 15thNight
52%
340
13%
1360
19%
340
57%
340
25%
768
July16th to endNight
56%
376
14%
1418
17%
354
60%
354
27%
792
August1st to 15thNight
58%
473
15%
1544
13%
471
61%
471
26%
962
August16th to endNight
56%
675
20%
1821
12%
675
60%
675
36%
1111
September1st to 15thNight
46%
720
15%
1800
7%
720
48%
720
28%
1246
September16th to endNight
49%
685
21%
1877
14%
685
53%
685
32%
1198
October1st to 15thNight
32%
660
17%
1980
12%
660
40%
660
20%
1383
October16th to endNight
27%
704
10%
2177
6%
704
33%
704
12%
1697
November1st to 15thNight
31%
700
15%
2376
13%
700
37%
700
15%
1681
November16th to endNight
22%
720
9%
2520
7%
720
25%
720
9%
1965
December1st to 15thNight
18%
720
7%
2520
3%
720
22%
720
7%
2048
December16th to endNight
17%
768
9%
2688
4%
768
22%
768
8%
2179

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
18%9%36%6%34446%32%
47974
Night
18%10%46%5%34446%31%
47082
TransparencyDay
52%411%20%9%1
47662
Night
54%411%19%9%
46912
SeeingDay
22%10%26%22%12%4
5423
Night
23%10%26%27%11%
14648

By Month

Percentage Cloud Cover NE (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
22%15%5%9%6%2333322%
1432
16th to endDay
15%16%6%8%8%3434423%
1607
February1st to 15thDay
13%14%5%11%8%4445%5%21%
1575
16th to endDay
16%14%5%8%6%34336%25%
1488
March1st to 15thDay
16%13%5%7%7%3434428%
1882
16th to endDay
14%6%5%5%6%33446%39%
2164
April1st to 15thDay
23%9%45%423336%33%
2152
16th to endDay
22%7%25%423435%37%
2265
May1st to 15thDay
20%8%36%5%2445%6%32%
2511
16th to endDay
16%6%35%7%345%5%7%34%
2618
June1st to 15thDay
21%6%36%6%25%45%7%30%
2520
16th to endDay
15%5%26%5%37%46%8%34%
2520
July1st to 15thDay
13%5%25%5%36%6%5%8%37%
2520
16th to endDay
11%5%25%5%37%6%6%9%36%
2654
August1st to 15thDay
12%5%26%7%45%45%7%36%
2403
16th to endDay
12%5%25%435%5%6%8%39%
2369
September1st to 15thDay
17%6%345%2335%6%41%
2160
16th to endDay
16%6%34325%346%43%
1893
October1st to 15thDay
22%8%25%5%33445%33%
1650
16th to endDay
30%9%36%5%24335%24%
1694
November1st to 15thDay
18%9%47%5%33436%32%
1481
16th to endDay
27%15%5%7%6%3433419%
1440
December1st to 15thDay
21%17%5%10%7%45%43415%
1440
16th to endDay
24%17%6%8%5%2333419%
1536
January1st to 15thNight
21%16%6%11%7%4443416%
2506
16th to endNight
15%15%5%8%6%35%445%25%
2616
February1st to 15thNight
13%14%6%12%7%35%44421%
2285
16th to endNight
16%13%5%9%7%3433427%
1984
March1st to 15thNight
19%13%47%7%3423428%
2052
16th to endNight
15%8%46%5%23245%41%
2058
April1st to 15thNight
22%10%35%434445%33%
1796
16th to endNight
19%8%36%423446%36%
1703
May1st to 15thNight
23%7%35%422445%36%
1440
16th to endNight
15%5%25%5%445%6%7%37%
1495
June1st to 15thNight
18%436%5%25%35%7%37%
1440
16th to endNight
15%5%245%35%5%5%7%37%
1440
July1st to 15thNight
12%4245%2445%8%45%
1440
16th to endNight
11%5%135%25%5%7%9%44%
1514
August1st to 15thNight
11%424435%5%7%7%42%
1554
16th to endNight
10%424424448%48%
1821
September1st to 15thNight
16%5%35%5%3335%7%40%
1800
16th to endNight
17%5%24313236%48%
1877
October1st to 15thNight
22%8%245%23335%37%
1980
16th to endNight
26%10%36%5%3445%5%24%
2177
November1st to 15thNight
20%9%35%5%25%45%6%31%
2376
16th to endNight
25%13%5%8%6%33335%22%
2520
December1st to 15thNight
22%18%5%9%6%3433418%
2520
16th to endNight
24%17%5%8%6%2333418%
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
68%39%12%6%
1433
16th to endDay
64%39%14%6%
1607
February1st to 15thDay
63%411%15%4
1577
16th to endDay
61%210%15%8%1
1488
March1st to 15thDay
59%311%17%7%1
1893
16th to endDay
45%39%21%15%4
2164
April1st to 15thDay
53%37%19%13%3
2152
16th to endDay
50%36%20%16%3
2265
May1st to 15thDay
51%39%18%14%2
2511
16th to endDay
48%5%10%19%13%2
2622
June1st to 15thDay
52%411%20%9%
2520
16th to endDay
46%6%12%21%12%1
2520
July1st to 15thDay
40%6%12%27%12%
2371
16th to endDay
42%6%16%24%10%
2487
August1st to 15thDay
45%6%15%21%10%
2389
16th to endDay
39%7%16%26%9%
2369
September1st to 15thDay
43%413%27%10%
2160
16th to endDay
42%412%31%8%
1893
October1st to 15thDay
54%312%18%10%
1650
16th to endDay
63%411%15%4
1694
November1st to 15thDay
52%415%19%7%
1481
16th to endDay
67%312%11%41
1440
December1st to 15thDay
72%49%10%2
1440
16th to endDay
69%310%12%4
1536
January1st to 15thNight
71%48%10%4
2506
16th to endNight
60%49%16%7%
2616
February1st to 15thNight
64%410%15%5%
2287
16th to endNight
61%29%18%8%
1984
March1st to 15thNight
61%39%18%7%
2064
16th to endNight
46%39%19%17%3
2058
April1st to 15thNight
54%27%18%14%2
1796
16th to endNight
49%27%19%16%3
1703
May1st to 15thNight
50%35%20%16%3
1440
16th to endNight
44%5%12%22%13%2
1497
June1st to 15thNight
46%5%13%23%9%1
1440
16th to endNight
45%5%12%22%14%
1440
July1st to 15thNight
36%5%13%26%17%1
1360
16th to endNight
34%6%14%30%13%
1418
August1st to 15thNight
37%8%16%24%12%
1544
16th to endNight
33%418%32%10%
1821
September1st to 15thNight
44%5%12%25%11%
1800
16th to endNight
39%214%35%7%
1877
October1st to 15thNight
50%410%23%11%
1980
16th to endNight
61%5%12%14%5%
2177
November1st to 15thNight
53%413%18%9%
2376
16th to endNight
65%411%14%3
2520
December1st to 15thNight
69%410%12%3
2520
16th to endNight
70%29%11%5%
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
30%16%25%23%5%
60
16th to endDay
40%13%22%15%7%
76
February1st to 15thDay
32%17%36%12%1
90
16th to endDay
34%18%28%14%4
147
March1st to 15thDay
25%14%33%21%5%
270
16th to endDay
20%13%31%21%10%2
288
April1st to 15thDay
30%17%26%14%10%1
270
16th to endDay
26%13%26%16%11%4
270
May1st to 15thDay
32%8%27%18%8%4
288
16th to endDay
19%16%28%23%9%1
331
June1st to 15thDay
27%9%24%24%11%1
315
16th to endDay
13%9%31%26%17%1
315
July1st to 15thDay
13%5%27%31%17%4
305
16th to endDay
12%428%32%16%6%
326
August1st to 15thDay
15%6%19%30%19%8%
313
16th to endDay
13%5%24%27%18%10%
332
September1st to 15thDay
20%5%20%23%16%14%
315
16th to endDay
16%9%20%23%19%9%
278
October1st to 15thDay
26%10%25%22%14%1
255
16th to endDay
35%12%25%18%7%
260
November1st to 15thDay
20%11%32%22%12%1
135
16th to endDay
36%15%31%8%6%1
60
December1st to 15thDay
16%16%43%16%5%1
60
16th to endDay
34%29%31%4
64
January1st to 15thNight
27%13%29%23%5%
720
16th to endNight
24%10%29%27%7%
768
February1st to 15thNight
20%11%35%23%7%1
704
16th to endNight
22%14%33%22%6%
631
March1st to 15thNight
27%12%29%25%5%
720
16th to endNight
19%14%27%26%12%
768
April1st to 15thNight
26%13%27%25%6%
718
16th to endNight
22%13%27%26%9%
623
May1st to 15thNight
26%6%25%30%10%1
360
16th to endNight
17%6%32%32%11%
375
June1st to 15thNight
20%6%26%36%9%
360
16th to endNight
18%424%37%14%
360
July1st to 15thNight
11%223%42%17%1
340
16th to endNight
12%319%44%18%1
376
August1st to 15thNight
14%217%36%26%2
473
16th to endNight
10%421%37%24%2
675
September1st to 15thNight
20%420%30%20%3
720
16th to endNight
19%5%19%29%22%2
685
October1st to 15thNight
26%8%26%25%13%
660
16th to endNight
31%9%25%24%8%
704
November1st to 15thNight
22%12%27%24%12%
700
16th to endNight
32%15%23%21%6%
720
December1st to 15thNight
31%13%29%20%4
720
16th to endNight
34%11%27%20%5%
768
Page generated at 2017-09-23 06:43:40. Version ac04

Copyright 2017 A. Danko


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