Little Knockem Down Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Knockem Down Observatory clear sky chart from 2005-11-05 to 2017-09-24.

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
71%
16207
18%
47088
17%
16169
72%
16169
29%
30023

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
65%
716
17%
2327
20%
716
66%
716
26%
1467
January16th to endNight
63%
768
25%
2364
24%
768
66%
768
33%
1397
February1st to 15thNight
62%
701
27%
2107
24%
699
66%
699
35%
1237
February16th to endNight
74%
631
31%
1767
27%
631
77%
631
45%
977
March1st to 15thNight
72%
720
26%
1980
20%
720
75%
720
42%
1152
March16th to endNight
73%
768
27%
2112
24%
768
75%
768
43%
1208
April1st to 15thNight
81%
718
22%
1976
20%
718
82%
718
45%
1120
April16th to endNight
76%
720
25%
1880
18%
720
78%
720
43%
1105
May1st to 15thNight
83%
719
24%
1799
18%
719
83%
719
53%
1013
May16th to endNight
70%
568
16%
1690
14%
568
70%
568
27%
1078
June1st to 15thNight
61%
540
8%
1620
7%
540
61%
540
16%
1213
June16th to endNight
74%
540
7%
1620
6%
540
74%
540
19%
1133
July1st to 15thNight
77%
510
6%
1530
7%
510
77%
510
23%
1029
July16th to endNight
81%
564
12%
1595
12%
531
81%
531
30%
985
August1st to 15thNight
77%
575
8%
1728
7%
572
77%
572
24%
1146
August16th to endNight
71%
764
6%
2101
6%
764
71%
764
19%
1554
September1st to 15thNight
72%
720
4%
1980
4%
720
72%
720
17%
1522
September16th to endNight
66%
693
5%
1914
5%
693
66%
693
16%
1505
October1st to 15thNight
64%
660
14%
1864
14%
660
64%
660
20%
1345
October16th to endNight
60%
704
16%
2112
17%
704
62%
704
21%
1468
November1st to 15thNight
67%
700
23%
2101
23%
700
70%
700
33%
1251
November16th to endNight
68%
720
26%
2160
27%
720
70%
720
33%
1290
December1st to 15thNight
69%
720
20%
2265
22%
720
71%
720
30%
1400
December16th to endNight
73%
768
24%
2496
27%
768
75%
768
33%
1428

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%425%6%36%7%8%11%35%
47826
Night
6%425%5%35%6%7%11%42%
47292
TransparencyDay
36%11%18%20%10%2
47527
Night
33%10%18%22%11%2
47095
SeeingDay
8%17%21%33%27%
6026
Night
7%19%25%36%20%
16217

By Month

Percentage Cloud Cover SE (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
10%425%5%36%6%6%12%36%
1611
16th to endDay
7%325%5%35%5%7%10%43%
1857
February1st to 15thDay
8%42442445%8%50%
1750
16th to endDay
42123145%5%11%56%
1704
March1st to 15thDay
3313335%6%7%11%49%
1980
16th to endDay
42144345%6%9%53%
2111
April1st to 15thDay
3213325%6%6%11%51%
1972
16th to endDay
43133245%6%11%52%
2079
May1st to 15thDay
421332347%12%53%
2152
16th to endDay
7%6%45%5%37%7%8%11%33%
2431
June1st to 15thDay
10%8%49%7%47%7%8%11%20%
2340
16th to endDay
6%5%26%8%5%9%10%10%15%21%
2340
July1st to 15thDay
5%5%36%8%410%9%11%14%20%
2340
16th to endDay
4325%6%5%9%10%12%16%22%
2465
August1st to 15thDay
3427%8%5%10%8%11%14%21%
2205
16th to endDay
7%5%37%8%5%9%10%9%12%20%
2101
September1st to 15thDay
7%6%37%9%6%9%9%11%12%16%
1980
16th to endDay
8%7%39%7%5%7%9%9%11%19%
1905
October1st to 15thDay
7%5%28%7%5%9%8%9%9%24%
1766
16th to endDay
12%6%27%5%36%6%6%9%32%
1760
November1st to 15thDay
7%4235%35%5%5%8%47%
1757
16th to endDay
8%5%244345%6%9%46%
1800
December1st to 15thDay
8%5%25%425%5%7%8%43%
1692
16th to endDay
43245%25%7%7%11%44%
1728
January1st to 15thNight
9%425%5%345%7%12%39%
2327
16th to endNight
5%424435%5%7%9%46%
2364
February1st to 15thNight
8%42432445%8%51%
2103
16th to endNight
421342445%8%58%
1767
March1st to 15thNight
3324425%45%8%54%
1980
16th to endNight
3314435%45%8%55%
2112
April1st to 15thNight
31133346%6%10%55%
1976
16th to endNight
5%31332445%10%53%
1880
May1st to 15thNight
31133235%5%10%60%
1799
16th to endNight
8%5%345%35%5%7%10%39%
1689
June1st to 15thNight
10%7%38%7%5%6%7%9%10%23%
1620
16th to endNight
45%15%8%47%9%8%13%31%
1620
July1st to 15thNight
4325%5%47%7%10%14%34%
1620
16th to endNight
32245%36%7%9%15%39%
1703
August1st to 15thNight
3425%5%46%7%10%15%34%
1739
16th to endNight
5%5%26%7%46%7%9%14%29%
2101
September1st to 15thNight
6%426%6%5%9%9%10%12%25%
1980
16th to endNight
6%7%37%7%47%8%10%11%24%
1914
October1st to 15thNight
7%5%27%8%46%7%8%11%29%
1864
16th to endNight
12%6%27%6%36%6%6%8%33%
2112
November1st to 15thNight
8%425%4235%6%10%46%
2101
16th to endNight
8%3234345%6%10%46%
2160
December1st to 15thNight
6%4245%36%5%6%10%43%
2265
16th to endNight
6%4244246%6%10%47%
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
38%8%16%21%12%3
1612
16th to endDay
32%8%14%22%16%4
1857
February1st to 15thDay
30%6%9%29%17%5%
1752
16th to endDay
21%6%14%33%18%6%
1704
March1st to 15thDay
24%6%15%32%18%2
1980
16th to endDay
25%5%16%29%19%3
2112
April1st to 15thDay
22%7%18%33%16%1
1972
16th to endDay
23%7%16%30%19%3
2079
May1st to 15thDay
22%6%19%30%16%4
2152
16th to endDay
38%11%17%25%7%
2435
June1st to 15thDay
52%13%18%13%2
2340
16th to endDay
44%18%28%8%
2340
July1st to 15thDay
43%19%27%8%
2201
16th to endDay
37%21%28%12%
2310
August1st to 15thDay
42%17%24%14%
2192
16th to endDay
46%17%25%11%
2101
September1st to 15thDay
50%20%21%7%
1980
16th to endDay
49%16%20%11%1
1905
October1st to 15thDay
47%14%13%16%5%2
1766
16th to endDay
43%9%13%17%12%3
1760
November1st to 15thDay
31%8%10%23%22%2
1757
16th to endDay
32%6%12%19%21%7%
1800
December1st to 15thDay
35%7%13%23%17%2
1692
16th to endDay
29%9%12%28%17%2
1728
January1st to 15thNight
36%9%17%25%8%2
2327
16th to endNight
31%7%15%24%16%3
2364
February1st to 15thNight
30%7%10%28%17%5%
2112
16th to endNight
23%6%14%27%20%7%
1767
March1st to 15thNight
26%7%13%28%21%2
1980
16th to endNight
25%7%16%27%19%4
2112
April1st to 15thNight
23%7%17%31%17%2
1976
16th to endNight
25%8%14%29%20%2
1880
May1st to 15thNight
19%6%17%33%18%4
1800
16th to endNight
37%8%16%25%10%
1691
June1st to 15thNight
50%11%21%13%3
1620
16th to endNight
40%15%31%12%
1620
July1st to 15thNight
34%16%34%13%
1530
16th to endNight
27%15%34%20%1
1595
August1st to 15thNight
33%16%29%19%1
1728
16th to endNight
41%17%27%13%
2101
September1st to 15thNight
42%20%25%9%1
1980
16th to endNight
46%18%21%10%1
1914
October1st to 15thNight
44%12%17%17%6%1
1864
16th to endNight
45%8%12%19%10%3
2112
November1st to 15thNight
32%7%15%23%19%2
2101
16th to endNight
31%8%14%19%21%4
2160
December1st to 15thNight
35%7%16%23%15%1
2265
16th to endNight
30%7%11%30%17%1
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
24%311%33%26%1
90
16th to endDay
13%8%19%38%17%2
96
February1st to 15thDay
4216%45%25%5%
90
16th to endDay
5%114%41%33%2
205
March1st to 15thDay
7%19%43%34%3
270
16th to endDay
7%114%36%32%6%
288
April1st to 15thDay
49%41%38%5%
270
16th to endDay
10%6%43%37%2
270
May1st to 15thDay
25%32%47%11%
288
16th to endDay
6%6%13%42%30%
331
June1st to 15thDay
14%7%13%31%32%
315
16th to endDay
418%24%59%
315
July1st to 15thDay
416%30%56%
305
16th to endDay
7%2431%53%
326
August1st to 15thDay
6%2335%51%
313
16th to endDay
8%39%30%46%
332
September1st to 15thDay
8%117%22%58%
315
16th to endDay
10%146%20%56%
287
October1st to 15thDay
8%6%19%45%19%
255
16th to endDay
18%112%26%27%13%
272
November1st to 15thDay
10%110%23%43%11%
265
16th to endDay
6%221%27%36%5%
270
December1st to 15thDay
15%115%28%33%5%
162
16th to endDay
5%18%23%53%8%
96
January1st to 15thNight
8%314%30%36%5%
720
16th to endNight
6%319%35%33%2
768
February1st to 15thNight
8%218%34%33%2
704
16th to endNight
5%211%39%37%3
631
March1st to 15thNight
4114%40%34%4
720
16th to endNight
4113%39%36%4
768
April1st to 15thNight
317%39%43%4
718
16th to endNight
6%9%41%38%3
720
May1st to 15thNight
35%29%49%10%
720
16th to endNight
8%16%21%44%17%
570
June1st to 15thNight
13%15%13%36%29%
540
16th to endNight
5%28%37%46%
540
July1st to 15thNight
236%36%51%
510
16th to endNight
415%31%57%
564
August1st to 15thNight
5%15%35%52%
575
16th to endNight
6%137%32%48%
764
September1st to 15thNight
6%47%28%51%
720
16th to endNight
9%46%30%49%
693
October1st to 15thNight
10%8%18%42%20%
660
16th to endNight
14%211%22%33%16%
704
November1st to 15thNight
9%210%30%37%9%
700
16th to endNight
7%113%31%39%6%
720
December1st to 15thNight
7%111%35%38%5%
720
16th to endNight
6%210%31%40%9%
768
Page generated at 2017-09-25 09:02:28. Version ac04

Copyright 2017 A. Danko


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