Lead Parachute Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lead Parachute Observatory clear sky chart from 2005-11-05 to 2017-10-06.

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
29%
15040
14%
47096
8%
15003
36%
15003
17%
33145

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
13%
719
10%
2503
4%
716
22%
716
7%
1922
January16th to endNight
14%
768
11%
2496
4%
768
24%
768
9%
1894
February1st to 15thNight
11%
704
11%
2287
3%
701
22%
701
8%
1737
February16th to endNight
14%
631
13%
1953
5%
631
25%
631
10%
1457
March1st to 15thNight
16%
720
15%
2022
6%
720
25%
720
13%
1540
March16th to endNight
21%
768
17%
2082
7%
768
30%
768
16%
1516
April1st to 15thNight
19%
718
13%
1796
4%
718
24%
718
16%
1358
April16th to endNight
30%
692
18%
1772
6%
692
35%
692
27%
1193
May1st to 15thNight
34%
450
16%
1530
9%
450
43%
450
16%
1066
May16th to endNight
42%
374
16%
1497
15%
374
50%
374
19%
952
June1st to 15thNight
40%
360
14%
1440
12%
360
49%
360
17%
929
June16th to endNight
47%
360
14%
1440
14%
360
56%
360
23%
842
July1st to 15thNight
51%
340
14%
1360
17%
340
57%
340
25%
789
July16th to endNight
60%
450
16%
1486
18%
422
64%
422
30%
855
August1st to 15thNight
57%
539
16%
1609
11%
536
60%
536
31%
1006
August16th to endNight
59%
714
21%
1860
13%
714
61%
714
34%
1179
September1st to 15thNight
45%
720
21%
1800
10%
720
49%
720
30%
1197
September16th to endNight
47%
717
23%
1977
17%
717
51%
717
30%
1279
October1st to 15thNight
38%
684
17%
2051
13%
684
45%
684
24%
1358
October16th to endNight
20%
704
13%
2112
5%
704
28%
704
15%
1526
November1st to 15thNight
26%
700
17%
2295
10%
700
36%
700
18%
1554
November16th to endNight
21%
720
13%
2520
8%
720
30%
720
11%
1847
December1st to 15thNight
14%
720
8%
2520
4%
720
20%
720
8%
1967
December16th to endNight
10%
768
7%
2688
2%
768
18%
768
6%
2182

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
15%9%47%6%35%45%6%30%
48104
Night
13%9%47%5%35%45%6%33%
47273
Cloud CoverDay
15%9%47%6%35%45%6%30%
48114
Night
13%9%47%5%35%45%6%33%
47278
TransparencyDay
52%6%11%18%10%1
47799
Night
49%6%12%19%10%1
47096
SeeingDay
21%14%27%19%11%5%
5622
Night
20%16%28%23%9%1
15042

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
13%9%7%13%9%45%45%5%21%
1435
16th to endDay
10%15%7%11%9%46%446%19%
1728
February1st to 15thDay
13%15%7%10%10%45%44420%
1575
16th to endDay
13%11%6%10%9%33445%25%
1518
March1st to 15thDay
17%13%6%8%5%2435%6%26%
1924
16th to endDay
14%11%48%5%35%446%30%
2142
April1st to 15thDay
16%13%5%7%43335%5%30%
2152
16th to endDay
16%9%25%424446%37%
2199
May1st to 15thDay
20%8%36%5%25%446%32%
2420
16th to endDay
15%8%36%6%35%5%5%7%33%
2618
June1st to 15thDay
18%7%37%6%345%5%6%32%
2520
16th to endDay
13%7%26%6%36%5%6%8%32%
2520
July1st to 15thDay
10%5%37%8%47%6%5%7%33%
2520
16th to endDay
10%5%36%6%47%5%6%9%33%
2577
August1st to 15thDay
11%6%36%7%5%6%6%6%8%31%
2340
16th to endDay
13%6%26%5%36%6%5%8%33%
2330
September1st to 15thDay
18%6%26%435%45%6%36%
2160
16th to endDay
16%6%145%34435%43%
1980
October1st to 15thDay
18%9%35%5%24348%34%
1707
16th to endDay
20%12%47%5%3445%6%25%
1760
November1st to 15thDay
12%11%46%43446%435%
1563
16th to endDay
18%13%46%5%34347%27%
1440
December1st to 15thDay
16%15%6%11%7%2445%5%20%
1440
16th to endDay
16%13%7%10%6%35%46%6%19%
1536
January1st to 15thNight
13%12%5%10%8%35%45%6%21%
2503
16th to endNight
11%12%5%9%7%5%7%5%5%6%22%
2496
February1st to 15thNight
11%14%6%8%7%26%45%6%24%
2285
16th to endNight
11%10%5%10%7%36%45%6%26%
1953
March1st to 15thNight
14%12%5%8%6%34446%28%
2010
16th to endNight
14%9%47%5%34345%35%
2082
April1st to 15thNight
18%10%5%6%6%23445%32%
1796
16th to endNight
14%8%25%42335%6%42%
1772
May1st to 15thNight
19%7%26%445%345%36%
1530
16th to endNight
11%6%35%6%4446%7%39%
1495
June1st to 15thNight
15%6%36%5%25%45%7%37%
1440
16th to endNight
9%425%5%35%5%6%10%41%
1440
July1st to 15thNight
7%435%5%2446%9%45%
1440
16th to endNight
9%425%5%2446%8%47%
1588
August1st to 15thNight
7%4145%35%5%6%9%45%
1620
16th to endNight
10%4244245%6%7%47%
1860
September1st to 15thNight
14%6%245%23447%44%
1800
16th to endNight
12%6%25%5%23446%45%
1977
October1st to 15thNight
16%6%35%5%23336%42%
2051
16th to endNight
19%11%36%5%335%47%29%
2112
November1st to 15thNight
13%10%36%424346%38%
2295
16th to endNight
16%12%47%5%35%45%6%27%
2520
December1st to 15thNight
17%14%6%8%5%3445%6%21%
2520
16th to endNight
16%13%7%10%7%45%5%5%6%17%
2688

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
13%9%8%13%9%45%45%5%21%
1435
16th to endDay
10%15%7%11%9%46%445%19%
1728
February1st to 15thDay
13%15%7%10%10%45%44420%
1575
16th to endDay
14%11%6%11%8%34445%25%
1518
March1st to 15thDay
17%13%6%8%5%23446%26%
1935
16th to endDay
14%11%5%7%6%35%446%30%
2141
April1st to 15thDay
16%13%5%7%43335%6%30%
2152
16th to endDay
16%9%25%5%2445%6%37%
2199
May1st to 15thDay
19%8%37%5%24446%31%
2420
16th to endDay
15%8%36%6%35%45%7%33%
2618
June1st to 15thDay
18%7%37%6%3445%6%32%
2520
16th to endDay
13%7%26%6%46%5%6%8%32%
2520
July1st to 15thDay
10%5%36%8%5%7%6%5%7%32%
2520
16th to endDay
10%6%36%6%47%5%6%9%33%
2577
August1st to 15thDay
11%6%26%7%46%6%6%9%31%
2340
16th to endDay
13%7%26%5%36%6%6%8%33%
2330
September1st to 15thDay
17%7%26%435%45%6%36%
2160
16th to endDay
16%6%245%24335%43%
1980
October1st to 15thDay
17%10%35%5%23248%34%
1707
16th to endDay
20%12%37%5%3445%6%25%
1760
November1st to 15thDay
12%11%46%435%46%5%35%
1563
16th to endDay
17%12%5%6%5%34347%27%
1440
December1st to 15thDay
16%15%6%11%7%2445%5%20%
1440
16th to endDay
15%13%7%11%6%35%45%6%19%
1536
January1st to 15thNight
13%12%5%11%7%45%45%7%21%
2503
16th to endNight
11%11%5%9%7%46%6%6%6%22%
2496
February1st to 15thNight
11%14%6%8%7%36%45%6%24%
2278
16th to endNight
11%10%6%10%7%36%5%5%6%26%
1953
March1st to 15thNight
14%12%5%8%7%34446%28%
2022
16th to endNight
14%9%47%5%35%446%35%
2082
April1st to 15thNight
18%10%47%6%23445%32%
1796
16th to endNight
14%8%25%32335%6%42%
1772
May1st to 15thNight
19%7%26%446%34436%
1530
16th to endNight
11%6%26%5%4446%7%39%
1495
June1st to 15thNight
15%6%36%5%25%45%7%37%
1440
16th to endNight
9%4245%35%5%6%10%42%
1440
July1st to 15thNight
7%5%245%3446%9%45%
1440
16th to endNight
9%42443445%8%46%
1588
August1st to 15thNight
7%4145%36%5%6%8%45%
1620
16th to endNight
10%42442446%6%48%
1860
September1st to 15thNight
14%6%25%433447%44%
1800
16th to endNight
12%6%26%5%23446%45%
1977
October1st to 15thNight
16%6%35%5%23436%42%
2051
16th to endNight
19%10%36%5%24447%29%
2112
November1st to 15thNight
13%10%36%424446%38%
2295
16th to endNight
16%12%47%6%36%45%5%27%
2520
December1st to 15thNight
17%15%7%7%5%35%5%5%6%21%
2520
16th to endNight
15%13%7%10%8%46%5%46%17%
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
63%5%10%12%6%1
1436
16th to endDay
65%5%11%12%4
1728
February1st to 15thDay
67%5%8%12%6%
1577
16th to endDay
59%49%17%7%
1518
March1st to 15thDay
59%412%16%7%
1935
16th to endDay
53%5%9%19%10%1
2142
April1st to 15thDay
54%48%19%11%
2152
16th to endDay
46%5%8%18%17%3
2199
May1st to 15thDay
52%5%10%20%9%1
2420
16th to endDay
49%7%12%16%12%1
2622
June1st to 15thDay
51%6%10%19%10%
2520
16th to endDay
47%7%12%22%9%1
2520
July1st to 15thDay
47%7%10%20%12%1
2371
16th to endDay
44%8%15%20%10%
2416
August1st to 15thDay
46%8%11%19%12%
2327
16th to endDay
45%6%11%21%12%1
2330
September1st to 15thDay
46%6%10%21%13%1
2160
16th to endDay
43%5%9%23%16%1
1980
October1st to 15thDay
49%411%18%14%1
1707
16th to endDay
58%5%13%16%6%
1760
November1st to 15thDay
48%6%12%18%10%3
1563
16th to endDay
57%412%18%7%
1440
December1st to 15thDay
64%5%13%11%4
1440
16th to endDay
64%6%13%12%3
1536
January1st to 15thNight
61%6%11%12%7%1
2503
16th to endNight
58%6%12%15%6%
2496
February1st to 15thNight
59%6%11%16%6%
2287
16th to endNight
57%5%9%17%8%
1953
March1st to 15thNight
56%5%9%19%7%
2022
16th to endNight
51%5%11%18%11%1
2082
April1st to 15thNight
53%6%9%18%11%
1796
16th to endNight
42%412%21%16%2
1772
May1st to 15thNight
50%6%9%21%12%
1530
16th to endNight
41%8%13%20%13%2
1497
June1st to 15thNight
45%5%12%23%11%
1440
16th to endNight
36%7%14%26%14%
1440
July1st to 15thNight
35%7%13%27%15%
1360
16th to endNight
32%6%18%24%15%2
1486
August1st to 15thNight
33%8%16%27%13%
1609
16th to endNight
33%7%13%26%17%1
1860
September1st to 15thNight
39%5%12%26%14%1
1800
16th to endNight
39%411%27%16%1
1977
October1st to 15thNight
43%5%13%20%16%1
2051
16th to endNight
53%5%14%18%7%
2112
November1st to 15thNight
47%5%13%18%11%3
2295
16th to endNight
56%5%12%17%7%
2520
December1st to 15thNight
62%6%13%12%4
2520
16th to endNight
66%6%12%10%3
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
31%29%24%6%6%1
61
16th to endDay
30%31%27%9%2
96
February1st to 15thDay
23%44%26%5%
90
16th to endDay
24%27%34%10%3
177
March1st to 15thDay
28%22%28%16%4
270
16th to endDay
27%24%22%16%6%3
288
April1st to 15thDay
30%16%30%13%7%1
270
16th to endDay
21%18%25%16%10%6%
270
May1st to 15thDay
36%14%22%12%10%4
288
16th to endDay
19%12%30%19%12%4
331
June1st to 15thDay
19%14%30%25%8%1
315
16th to endDay
20%12%34%21%9%1
315
July1st to 15thDay
11%7%32%28%12%7%
305
16th to endDay
10%6%29%30%16%7%
326
August1st to 15thDay
11%6%30%24%17%10%
313
16th to endDay
13%7%22%24%15%16%
332
September1st to 15thDay
17%9%24%18%20%10%
315
16th to endDay
15%9%19%22%21%11%
314
October1st to 15thDay
25%7%21%21%16%7%
278
16th to endDay
30%17%29%18%3
272
November1st to 15thDay
20%15%26%22%13%1
212
16th to endDay
21%21%35%18%3
60
December1st to 15thDay
25%28%28%8%8%1
60
16th to endDay
34%37%25%3
64
January1st to 15thNight
23%27%31%13%3
720
16th to endNight
20%25%34%17%1
768
February1st to 15thNight
25%26%32%14%
704
16th to endNight
25%24%32%15%1
631
March1st to 15thNight
26%25%29%15%2
720
16th to endNight
22%24%26%19%5%1
768
April1st to 15thNight
26%22%28%18%3
718
16th to endNight
21%13%32%22%10%
692
May1st to 15thNight
23%10%26%27%12%
450
16th to endNight
12%10%29%32%14%
375
June1st to 15thNight
18%11%22%36%11%
360
16th to endNight
11%430%40%12%
360
July1st to 15thNight
8%5%30%37%17%1
340
16th to endNight
10%418%42%22%2
450
August1st to 15thNight
9%323%37%22%3
539
16th to endNight
10%418%35%27%3
714
September1st to 15thNight
17%7%21%30%20%1
720
16th to endNight
16%7%22%23%22%7%
717
October1st to 15thNight
20%12%23%24%16%2
684
16th to endNight
25%16%30%22%3
704
November1st to 15thNight
19%17%33%21%7%1
700
16th to endNight
27%20%26%19%41
720
December1st to 15thNight
28%22%30%14%3
720
16th to endNight
26%24%32%13%2
768
Page generated at 2017-10-07 14:07:56. Version ac04

Copyright 2017 A. Danko


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