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Rott'n Paws Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rott'n Paws Observatory clear sky chart from 2005-11-05 to 2019-04-11.

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
43%
17592
20%
53374
13%
17556
51%
17556
25%
34096

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
27%
836
22%
2786
9%
836
44%
836
20%
1737
January16th to endNight
26%
896
22%
2912
11%
896
41%
896
23%
1821
February1st to 15thNight
24%
821
19%
2627
10%
821
37%
821
22%
1666
February16th to endNight
24%
735
25%
2205
11%
735
41%
735
26%
1362
March1st to 15thNight
30%
840
21%
2370
10%
840
42%
840
26%
1542
March16th to endNight
31%
896
19%
2408
10%
896
39%
896
25%
1630
April1st to 15thNight
33%
822
21%
2056
7%
822
42%
822
31%
1373
April16th to endNight
41%
771
19%
1927
8%
771
45%
771
32%
1286
May1st to 15thNight
41%
748
14%
1918
7%
748
45%
748
26%
1331
May16th to endNight
62%
406
17%
1625
18%
406
65%
406
23%
968
June1st to 15thNight
64%
390
16%
1560
19%
390
67%
390
23%
933
June16th to endNight
67%
390
15%
1560
18%
390
70%
390
22%
929
July1st to 15thNight
70%
392
15%
1502
18%
392
71%
392
24%
896
July16th to endNight
68%
612
15%
1739
13%
579
71%
579
29%
1113
August1st to 15thNight
65%
644
13%
1784
9%
641
66%
641
27%
1216
August16th to endNight
63%
828
16%
2070
10%
828
63%
828
28%
1434
September1st to 15thNight
63%
780
22%
1950
15%
780
65%
780
31%
1323
September16th to endNight
51%
777
17%
2110
14%
777
54%
777
25%
1471
October1st to 15thNight
52%
780
23%
2340
20%
780
58%
780
27%
1503
October16th to endNight
45%
832
30%
2496
23%
832
57%
832
34%
1449
November1st to 15thNight
41%
820
21%
2598
15%
820
50%
820
25%
1633
November16th to endNight
41%
840
24%
2755
18%
840
50%
840
27%
1633
December1st to 15thNight
33%
840
19%
2940
12%
840
44%
840
19%
1888
December16th to endNight
31%
896
22%
3136
13%
896
44%
896
22%
1959

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
13%5%25%4245%5%7%41%
53812
Night
13%5%25%42445%7%43%
53559
Cloud CoverDay
13%5%25%43445%7%41%
53822
Night
13%5%25%42445%7%43%
53563
TransparencyDay
40%7%12%21%15%2
53516
Night
39%6%12%21%16%3
53374
SeeingDay
17%7%23%26%18%6%
7841
Night
16%7%26%31%15%2
17600

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
16%7%243235%5%5%43%
1809
16th to endDay
15%6%2432445%6%46%
2016
February1st to 15thDay
15%7%25%424446%43%
1893
16th to endDay
16%5%245%235%48%41%
1840
March1st to 15thDay
14%6%24323345%48%
2235
16th to endDay
17%5%23324445%44%
2518
April1st to 15thDay
13%424423347%49%
2457
16th to endDay
13%425%424447%45%
2308
May1st to 15thDay
15%5%25%4245%5%8%40%
2373
16th to endDay
13%5%25%5%245%5%7%40%
2841
June1st to 15thDay
10%424435%5%8%10%40%
2730
16th to endDay
8%4246%36%6%8%11%37%
2730
July1st to 15thDay
8%425%5%36%6%8%10%37%
2704
16th to endDay
9%425%6%37%6%7%11%33%
2673
August1st to 15thDay
10%5%26%6%36%6%7%8%33%
2403
16th to endDay
11%6%25%6%36%6%7%10%32%
2484
September1st to 15thDay
13%5%25%5%35%5%5%9%38%
2340
16th to endDay
21%7%26%6%35%45%6%31%
2176
October1st to 15thDay
17%6%34425%435%43%
1950
16th to endDay
12%314323345%52%
2080
November1st to 15thDay
19%6%24313435%44%
1918
16th to endDay
13%423413345%51%
1862
December1st to 15thDay
15%6%25%5%2435%6%41%
1680
16th to endDay
19%6%25%323445%41%
1792
January1st to 15thNight
13%6%25%42445%6%43%
2786
16th to endNight
17%6%24424236%44%
2912
February1st to 15thNight
17%7%24423445%43%
2626
16th to endNight
14%7%25%323346%46%
2205
March1st to 15thNight
15%5%14424446%46%
2358
16th to endNight
17%5%25%434345%42%
2408
April1st to 15thNight
12%6%15%43345%7%45%
2056
16th to endNight
16%42432335%7%45%
1927
May1st to 15thNight
14%6%25%425%46%8%40%
1918
16th to endNight
11%5%2442445%8%45%
1623
June1st to 15thNight
8%5%345%36%47%10%40%
1560
16th to endNight
6%325%5%36%6%7%9%43%
1560
July1st to 15thNight
7%426%5%346%6%11%41%
1583
16th to endNight
8%4345%35%6%8%10%39%
1847
August1st to 15thNight
8%5%25%6%45%5%7%10%38%
1795
16th to endNight
10%5%26%6%35%5%6%10%38%
2070
September1st to 15thNight
12%5%26%43435%7%44%
1950
16th to endNight
17%5%36%5%3335%8%37%
2110
October1st to 15thNight
15%5%15%424445%45%
2340
16th to endNight
12%413423345%53%
2496
November1st to 15thNight
17%6%24323446%44%
2598
16th to endNight
13%424423446%48%
2755
December1st to 15thNight
15%6%35%5%34346%40%
2940
16th to endNight
16%7%25%423446%42%
3136

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
16%7%343235%5%5%43%
1809
16th to endDay
14%6%24324446%46%
2016
February1st to 15thDay
15%7%25%42435%6%43%
1893
16th to endDay
15%5%25%4235%5%7%41%
1840
March1st to 15thDay
14%6%24423335%48%
2246
16th to endDay
17%6%24324445%44%
2517
April1st to 15thDay
13%5%24423337%49%
2457
16th to endDay
13%426%424446%45%
2308
May1st to 15thDay
14%5%35%43445%8%40%
2373
16th to endDay
13%5%25%5%345%6%7%41%
2841
June1st to 15thDay
10%424435%5%7%10%40%
2730
16th to endDay
8%5%145%36%6%7%12%37%
2730
July1st to 15thDay
8%415%5%36%7%8%10%37%
2704
16th to endDay
8%5%25%6%47%6%7%11%33%
2673
August1st to 15thDay
10%5%26%6%46%6%7%8%33%
2403
16th to endDay
11%5%25%5%46%5%7%10%32%
2484
September1st to 15thDay
13%5%25%5%35%5%5%9%38%
2340
16th to endDay
20%6%26%5%35%5%46%31%
2176
October1st to 15thDay
17%6%25%424445%42%
1950
16th to endDay
12%325%323435%53%
2080
November1st to 15thDay
19%6%24413335%44%
1918
16th to endDay
13%32342435%5%51%
1862
December1st to 15thDay
15%6%25%5%24346%41%
1680
16th to endDay
19%6%24423445%41%
1792
January1st to 15thNight
14%6%25%42346%6%42%
2786
16th to endNight
17%5%245%24336%44%
2912
February1st to 15thNight
17%6%2432345%5%43%
2619
16th to endNight
14%6%34323346%46%
2205
March1st to 15thNight
15%5%24424446%45%
2370
16th to endNight
17%5%25%424346%42%
2408
April1st to 15thNight
12%5%15%43345%7%45%
2056
16th to endNight
16%414424347%45%
1927
May1st to 15thNight
14%5%245%25%45%8%39%
1917
16th to endNight
11%5%245%2445%8%45%
1623
June1st to 15thNight
8%5%34436%47%10%40%
1560
16th to endNight
5%425%5%36%5%7%9%43%
1560
July1st to 15thNight
7%426%5%35%5%7%12%41%
1583
16th to endNight
8%5%25%5%36%6%8%10%39%
1847
August1st to 15thNight
8%5%26%6%346%6%10%38%
1795
16th to endNight
10%5%26%6%35%5%6%9%38%
2070
September1st to 15thNight
11%5%25%5%3435%8%44%
1950
16th to endNight
17%6%26%5%3435%7%37%
2110
October1st to 15thNight
15%5%25%424445%46%
2340
16th to endNight
12%313323345%54%
2496
November1st to 15thNight
17%6%24413446%44%
2598
16th to endNight
13%424424446%48%
2755
December1st to 15thNight
16%6%35%434446%40%
2940
16th to endNight
16%7%25%423346%43%
3136

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
41%5%10%21%17%4
1810
16th to endDay
39%410%24%16%4
2016
February1st to 15thDay
42%410%22%15%3
1896
16th to endDay
40%6%12%20%16%4
1840
March1st to 15thDay
39%410%21%19%4
2246
16th to endDay
41%5%11%20%18%3
2518
April1st to 15thDay
35%412%24%19%4
2457
16th to endDay
38%6%10%18%18%7%
2308
May1st to 15thDay
42%7%14%21%12%2
2373
16th to endDay
40%8%13%22%13%1
2845
June1st to 15thDay
34%10%16%23%13%
2730
16th to endDay
36%9%17%20%13%1
2730
July1st to 15thDay
35%12%16%22%10%1
2557
16th to endDay
39%9%16%20%11%1
2518
August1st to 15thDay
43%10%15%19%10%
2390
16th to endDay
43%9%15%17%11%2
2484
September1st to 15thDay
42%8%13%18%14%2
2340
16th to endDay
50%7%10%16%13%
2176
October1st to 15thDay
43%48%22%17%2
1950
16th to endDay
33%5%7%25%23%5%
2080
November1st to 15thDay
43%412%19%17%3
1918
16th to endDay
35%411%25%19%4
1862
December1st to 15thDay
43%412%21%14%3
1680
16th to endDay
44%49%24%13%3
1792
January1st to 15thNight
40%6%10%21%16%4
2786
16th to endNight
41%49%21%17%5%
2912
February1st to 15thNight
41%49%22%17%3
2627
16th to endNight
38%310%24%17%5%
2205
March1st to 15thNight
39%6%11%22%16%3
2370
16th to endNight
43%5%9%20%17%3
2408
April1st to 15thNight
37%6%12%20%19%3
2056
16th to endNight
38%5%10%20%18%5%
1927
May1st to 15thNight
41%8%13%22%11%2
1918
16th to endNight
34%10%16%22%12%2
1625
June1st to 15thNight
36%9%16%24%11%1
1560
16th to endNight
34%11%18%18%14%1
1560
July1st to 15thNight
33%11%17%23%10%2
1502
16th to endNight
33%11%17%24%11%1
1739
August1st to 15thNight
39%10%18%20%10%
1784
16th to endNight
40%8%14%23%10%1
2070
September1st to 15thNight
39%7%15%20%14%3
1950
16th to endNight
45%6%12%17%16%1
2110
October1st to 15thNight
39%6%10%23%18%2
2340
16th to endNight
31%5%8%25%24%5%
2496
November1st to 15thNight
41%5%10%18%19%4
2598
16th to endNight
35%5%9%23%19%5%
2755
December1st to 15thNight
44%5%11%20%14%2
2940
16th to endNight
42%411%22%14%3
3136

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
22%23%31%18%4
159
16th to endDay
16%19%35%22%41
192
February1st to 15thDay
21%17%38%15%5%
229
16th to endDay
18%13%39%25%3
343
March1st to 15thDay
17%15%38%22%5%1
390
16th to endDay
17%10%36%26%7%1
416
April1st to 15thDay
15%12%35%22%10%2
372
16th to endDay
17%7%27%29%15%2
319
May1st to 15thDay
22%431%24%13%2
348
16th to endDay
19%317%27%23%8%
395
June1st to 15thDay
15%215%28%29%9%
375
16th to endDay
11%118%33%28%6%
375
July1st to 15thDay
10%18%32%35%11%
365
16th to endDay
11%19%31%33%13%
390
August1st to 15thDay
10%110%35%27%14%
358
16th to endDay
11%19%27%31%18%
396
September1st to 15thDay
16%313%23%21%21%
375
16th to endDay
24%314%25%23%9%
374
October1st to 15thDay
21%318%26%22%8%
375
16th to endDay
14%7%29%25%18%5%
400
November1st to 15thDay
24%6%29%22%13%4
345
16th to endDay
13%13%28%24%17%2
302
December1st to 15thDay
24%10%38%17%8%1
120
16th to endDay
22%14%35%23%4
128
January1st to 15thNight
17%15%34%25%7%
840
16th to endNight
19%12%37%26%3
896
February1st to 15thNight
20%12%38%25%3
824
16th to endNight
17%15%39%23%3
735
March1st to 15thNight
17%10%37%27%6%
840
16th to endNight
20%8%35%27%7%
896
April1st to 15thNight
15%8%38%28%8%
822
16th to endNight
19%5%30%34%9%1
771
May1st to 15thNight
17%5%29%37%9%
748
16th to endNight
14%214%43%22%2
407
June1st to 15thNight
8%215%43%25%4
390
16th to endNight
7%115%47%27%1
390
July1st to 15thNight
8%111%44%31%3
392
16th to endNight
9%111%40%33%4
612
August1st to 15thNight
10%111%41%31%4
644
16th to endNight
12%18%36%35%5%
828
September1st to 15thNight
14%111%35%29%7%
780
16th to endNight
20%214%31%28%2
777
October1st to 15thNight
17%318%31%23%4
780
16th to endNight
15%8%27%28%16%3
832
November1st to 15thNight
19%6%26%29%14%2
820
16th to endNight
15%9%30%29%14%1
840
December1st to 15thNight
20%9%31%27%10%
840
16th to endNight
20%9%34%29%6%
896
Page generated at 2019-04-12 19:23:21. Version ac04

Copyright 2019 A. Danko


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