White Tail Run Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the White Tail Run Observatory clear sky chart from 2005-11-05 to 2017-09-23.

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
50%
15409
27%
47048
19%
15366
59%
15366
36%
26424

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
42%
895
28%
2327
13%
895
51%
895
35%
1436
January16th to endNight
43%
777
33%
2313
18%
777
54%
777
35%
1313
February1st to 15thNight
40%
704
30%
2106
14%
698
53%
698
35%
1139
February16th to endNight
31%
632
30%
1894
11%
632
47%
632
36%
1040
March1st to 15thNight
35%
627
29%
2067
14%
627
50%
627
31%
1148
March16th to endNight
31%
576
26%
2112
16%
576
46%
576
29%
1156
April1st to 15thNight
27%
539
26%
1910
13%
539
45%
539
30%
1043
April16th to endNight
26%
540
27%
1800
14%
540
46%
540
30%
1040
May1st to 15thNight
30%
540
22%
1623
14%
540
41%
540
31%
974
May16th to endNight
42%
562
24%
1684
16%
561
54%
561
32%
1027
June1st to 15thNight
58%
540
22%
1620
19%
540
67%
540
52%
798
June16th to endNight
58%
540
21%
1620
21%
540
63%
540
39%
927
July1st to 15thNight
70%
510
21%
1530
21%
510
74%
510
39%
865
July16th to endNight
83%
564
26%
1625
29%
531
86%
531
45%
847
August1st to 15thNight
87%
539
26%
1789
32%
536
87%
536
49%
837
August16th to endNight
73%
573
23%
1910
27%
573
75%
573
31%
1118
September1st to 15thNight
74%
540
19%
1976
23%
540
75%
540
30%
1119
September16th to endNight
67%
516
23%
1903
25%
516
69%
516
28%
1107
October1st to 15thNight
65%
495
34%
1815
33%
495
70%
495
40%
887
October16th to endNight
61%
635
37%
2043
27%
635
69%
635
48%
977
November1st to 15thNight
55%
805
29%
2205
16%
805
61%
805
42%
1249
November16th to endNight
51%
900
32%
2340
16%
900
58%
900
42%
1350
December1st to 15thNight
47%
900
29%
2340
17%
900
52%
900
35%
1466
December16th to endNight
40%
960
27%
2496
13%
960
48%
960
33%
1561

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%24424447%46%
47845
Night
11%413323347%54%
47253
Cloud CoverDay
13%5%24424447%47%
47843
Night
10%413323347%54%
47253
TransparencyDay
36%410%19%18%10%
47547
Night
29%411%20%19%13%
47055
SeeingDay
14%422%33%21%3
5340
Night
13%5%26%37%15%1
15415

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
14%5%23322246%51%
1611
16th to endDay
13%5%12323345%54%
1920
February1st to 15thDay
12%5%23322335%53%
1750
16th to endDay
14%412323345%54%
1580
March1st to 15thDay
19%5%23212236%49%
1891
16th to endDay
18%6%12323445%49%
2112
April1st to 15thDay
17%5%23323246%48%
2035
16th to endDay
15%425%423346%47%
2160
May1st to 15thDay
17%4243245%5%7%41%
2328
16th to endDay
19%6%345%24347%38%
2430
June1st to 15thDay
8%313335%45%9%51%
2340
16th to endDay
13%5%26%5%35%6%6%8%35%
2340
July1st to 15thDay
12%6%25%435%5%5%7%40%
2340
16th to endDay
9%3245%25%5%6%10%43%
2429
August1st to 15thDay
3214335%6%5%10%53%
2160
16th to endDay
9%415%6%35%5%5%10%41%
2292
September1st to 15thDay
11%5%36%5%46%6%47%36%
1983
16th to endDay
12%6%26%5%4445%7%41%
1893
October1st to 15thDay
12%5%14324346%50%
1815
16th to endDay
10%413213335%60%
1818
November1st to 15thDay
15%6%24423345%47%
1650
16th to endDay
14%6%3422223354%
1620
December1st to 15thDay
19%6%23312235%47%
1620
16th to endDay
14%7%24322346%48%
1728
January1st to 15thNight
14%5%1332333453%
2327
16th to endNight
13%424322345%54%
2313
February1st to 15thNight
11%423212335%58%
2102
16th to endNight
12%322323337%55%
1894
March1st to 15thNight
15%413322336%52%
2067
16th to endNight
14%423312345%53%
2112
April1st to 15thNight
12%313323246%53%
1910
16th to endNight
12%424422436%51%
1800
May1st to 15thNight
13%5%25%32345%6%49%
1622
16th to endNight
13%423324348%49%
1683
June1st to 15thNight
32221246%8%64%
1620
16th to endNight
6%323325%45%9%52%
1620
July1st to 15thNight
7%313325%46%9%50%
1620
16th to endNight
5%2123245%5%11%55%
1735
August1st to 15thNight
22123245%5%9%62%
1800
16th to endNight
7%3244345%6%9%47%
1910
September1st to 15thNight
7%5%2342446%11%45%
1976
16th to endNight
11%5%134245%5%7%46%
1903
October1st to 15thNight
11%212212346%61%
1815
16th to endNight
8%2122223467%
2043
November1st to 15thNight
11%313212345%58%
2205
16th to endNight
12%413212235%59%
2340
December1st to 15thNight
17%5%12312346%50%
2340
16th to endNight
14%6%23313235%52%
2496

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
14%5%23422236%51%
1611
16th to endDay
12%5%22323335%54%
1920
February1st to 15thDay
12%6%13322345%54%
1750
16th to endDay
13%412224345%54%
1580
March1st to 15thDay
19%5%13312236%49%
1891
16th to endDay
18%5%12322345%49%
2110
April1st to 15thDay
16%424323346%48%
2035
16th to endDay
14%434423347%47%
2160
May1st to 15thDay
15%5%24425%46%7%41%
2328
16th to endDay
17%5%35%5%34446%39%
2430
June1st to 15thDay
8%31332445%9%51%
2340
16th to endDay
12%5%25%6%36%6%5%8%36%
2340
July1st to 15thDay
12%5%35%5%25%5%5%7%40%
2340
16th to endDay
9%324435%5%6%9%45%
2429
August1st to 15thDay
3214435%45%10%54%
2160
16th to endDay
9%425%5%45%5%5%8%41%
2292
September1st to 15thDay
11%6%35%6%5%6%5%5%7%36%
1983
16th to endDay
11%6%26%5%3445%6%42%
1893
October1st to 15thDay
12%42342435%7%50%
1815
16th to endDay
10%413223335%60%
1818
November1st to 15thDay
14%6%24413345%47%
1650
16th to endDay
14%6%2422223355%
1620
December1st to 15thDay
18%7%24312335%48%
1620
16th to endDay
14%7%33323246%48%
1728
January1st to 15thNight
13%6%13323335%53%
2327
16th to endNight
13%423322245%53%
2313
February1st to 15thNight
10%5%13213335%58%
2102
16th to endNight
11%413323346%55%
1894
March1st to 15thNight
14%423323336%52%
2067
16th to endNight
14%422322345%54%
2112
April1st to 15thNight
10%413423346%53%
1910
16th to endNight
11%5%25%323336%52%
1800
May1st to 15thNight
11%6%24323446%49%
1622
16th to endNight
12%42342335%8%50%
1683
June1st to 15thNight
32231346%8%64%
1620
16th to endNight
6%2233245%5%9%53%
1620
July1st to 15thNight
7%3133245%6%10%50%
1620
16th to endNight
5%2232446%11%55%
1735
August1st to 15thNight
21123245%410%62%
1800
16th to endNight
7%3244345%6%9%47%
1910
September1st to 15thNight
7%4244245%7%10%46%
1976
16th to endNight
11%5%25%3235%6%7%47%
1903
October1st to 15thNight
11%312212337%61%
1815
16th to endNight
7%31221233468%
2043
November1st to 15thNight
10%41331235%5%59%
2205
16th to endNight
12%412212245%59%
2340
December1st to 15thNight
16%5%12312346%50%
2340
16th to endNight
14%7%24312335%52%
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
35%25%18%22%15%
1612
16th to endDay
32%37%14%25%17%
1920
February1st to 15thDay
33%37%13%21%20%
1751
16th to endDay
31%36%16%25%15%
1580
March1st to 15thDay
37%37%16%17%17%
1891
16th to endDay
37%47%17%18%14%
2112
April1st to 15thDay
37%37%15%18%17%
2035
16th to endDay
37%37%19%17%14%
2160
May1st to 15thDay
40%5%10%16%18%8%
2328
16th to endDay
45%5%9%16%18%3
2434
June1st to 15thDay
29%5%14%24%20%6%
2340
16th to endDay
43%7%12%18%15%3
2340
July1st to 15thDay
38%6%13%25%14%1
2201
16th to endDay
30%7%21%29%10%
2277
August1st to 15thDay
23%6%15%37%15%1
2147
16th to endDay
38%7%15%25%10%2
2292
September1st to 15thDay
44%8%11%17%15%2
1983
16th to endDay
41%5%10%18%15%8%
1893
October1st to 15thDay
33%5%9%21%20%9%
1815
16th to endDay
26%35%16%28%18%
1818
November1st to 15thDay
38%37%19%18%11%
1650
16th to endDay
35%2412%19%24%
1620
December1st to 15thDay
40%37%15%21%11%
1620
16th to endDay
37%36%16%24%12%
1728
January1st to 15thNight
35%25%16%20%19%
2327
16th to endNight
32%25%16%22%19%
2313
February1st to 15thNight
28%37%13%21%25%
2112
16th to endNight
29%27%16%24%18%
1894
March1st to 15thNight
32%49%13%20%20%
2067
16th to endNight
32%49%18%19%15%
2112
April1st to 15thNight
32%411%15%17%19%
1910
16th to endNight
33%410%19%15%15%
1800
May1st to 15thNight
34%5%11%20%15%12%
1623
16th to endNight
32%7%12%23%17%4
1685
June1st to 15thNight
16%6%16%29%25%4
1620
16th to endNight
27%6%17%25%18%4
1620
July1st to 15thNight
27%6%19%27%16%2
1530
16th to endNight
19%8%23%33%14%
1625
August1st to 15thNight
17%6%22%35%17%
1789
16th to endNight
31%8%19%25%11%2
1910
September1st to 15thNight
30%8%16%21%18%4
1976
16th to endNight
34%7%15%19%15%8%
1903
October1st to 15thNight
24%412%26%20%11%
1815
16th to endNight
21%26%16%30%21%
2043
November1st to 15thNight
27%47%23%23%14%
2205
16th to endNight
28%37%14%20%26%
2340
December1st to 15thNight
35%38%17%21%14%
2340
16th to endNight
36%26%17%20%17%
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
14%7%41%30%6%
90
16th to endDay
16%12%36%23%9%1
96
February1st to 15thDay
13%18%23%24%18%1
90
16th to endDay
19%11%38%24%6%
81
March1st to 15thDay
32%7%35%18%5%
90
16th to endDay
12%6%46%30%4
96
April1st to 15thDay
16%16%45%21%
154
16th to endDay
12%12%44%24%5%
270
May1st to 15thDay
19%9%42%22%4
465
16th to endDay
24%6%30%29%8%
517
June1st to 15thDay
11%18%47%20%2
495
16th to endDay
13%117%38%23%5%
495
July1st to 15thDay
12%113%39%30%3
475
16th to endDay
9%1334%45%5%
478
August1st to 15thDay
45%43%38%8%
315
16th to endDay
12%28%41%27%8%
332
September1st to 15thDay
7%232%52%4
138
16th to endDay
7%328%49%9%
111
October1st to 15thDay
5%17%53%27%4
90
16th to endDay
14%317%41%20%2
96
November1st to 15thDay
33%325%24%12%1
90
16th to endDay
25%14%25%22%8%3
90
December1st to 15thDay
31%315%32%13%4
90
16th to endDay
26%7%30%31%41
96
January1st to 15thNight
17%9%27%35%9%
900
16th to endNight
16%6%27%38%10%
777
February1st to 15thNight
15%11%28%34%8%
704
16th to endNight
15%8%41%30%3
632
March1st to 15thNight
18%6%37%31%5%
627
16th to endNight
14%9%42%28%4
576
April1st to 15thNight
12%9%48%27%1
539
16th to endNight
11%11%49%23%3
540
May1st to 15thNight
14%10%43%28%3
540
16th to endNight
12%5%36%36%9%
563
June1st to 15thNight
5%31%51%10%
540
16th to endNight
6%227%46%17%
540
July1st to 15thNight
8%115%51%23%
510
16th to endNight
5%16%57%28%1
564
August1st to 15thNight
1450%41%1
539
16th to endNight
7%9%48%31%2
573
September1st to 15thNight
7%8%42%37%2
540
16th to endNight
14%11%38%31%3
516
October1st to 15thNight
12%117%40%24%2
495
16th to endNight
8%423%36%25%2
635
November1st to 15thNight
13%423%35%20%2
805
16th to endNight
15%6%23%37%15%2
900
December1st to 15thNight
19%6%22%36%13%1
900
16th to endNight
19%9%26%33%10%
960
Page generated at 2017-09-24 08:15:53. Version ac04

Copyright 2017 A. Danko


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