Pennyrile Forest Observing Field
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pennyrile Forest Observing Field clear sky chart from 2005-11-05 to 2017-08-12.

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%
15548
22%
46454
15%
15504
50%
15504
27%
29215

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
24%
900
19%
2506
8%
895
34%
895
20%
1741
January16th to endNight
22%
909
20%
2508
8%
909
32%
909
22%
1712
February1st to 15thNight
20%
704
17%
2112
6%
701
29%
701
18%
1479
February16th to endNight
18%
631
19%
1893
7%
631
29%
631
19%
1300
March1st to 15thNight
25%
720
18%
2160
9%
720
33%
720
21%
1457
March16th to endNight
32%
647
17%
2020
10%
647
39%
647
21%
1357
April1st to 15thNight
35%
539
23%
1797
13%
539
51%
539
29%
1034
April16th to endNight
41%
540
23%
1797
17%
540
50%
540
28%
1077
May1st to 15thNight
39%
539
18%
1619
10%
539
47%
539
26%
1061
May16th to endNight
60%
561
20%
1671
15%
561
64%
561
30%
1038
June1st to 15thNight
65%
540
22%
1440
15%
540
68%
540
42%
856
June16th to endNight
73%
540
24%
1440
18%
540
75%
540
42%
841
July1st to 15thNight
68%
510
18%
1360
14%
510
70%
510
35%
846
July16th to endNight
74%
564
24%
1472
20%
531
76%
531
40%
852
August1st to 15thNight
77%
527
23%
1727
27%
524
78%
524
37%
933
August16th to endNight
75%
525
25%
1750
29%
525
76%
525
37%
940
September1st to 15thNight
64%
525
26%
1680
25%
525
68%
525
32%
981
September16th to endNight
58%
657
27%
1815
20%
657
61%
657
35%
1114
October1st to 15thNight
55%
660
33%
1834
25%
660
61%
660
37%
1082
October16th to endNight
41%
704
28%
2203
20%
704
51%
704
31%
1312
November1st to 15thNight
44%
700
30%
2276
24%
700
55%
700
33%
1277
November16th to endNight
33%
720
24%
2340
16%
720
44%
720
26%
1411
December1st to 15thNight
27%
726
17%
2346
11%
726
35%
726
18%
1594
December16th to endNight
23%
960
18%
2688
7%
960
33%
960
19%
1920

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%6%25%5%3445%7%41%
47525
Night
14%6%2442345%6%44%
46636
TransparencyDay
41%6%11%22%15%3
47209
Night
39%5%10%23%17%3
46456
SeeingDay
14%8%21%25%19%10%
5560
Night
17%9%25%27%17%2
15551

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
21%7%36%5%23445%35%
1432
16th to endDay
14%7%36%6%3434440%
1714
February1st to 15thDay
15%11%45%5%2234439%
1750
16th to endDay
16%10%35%5%25%446%35%
1580
March1st to 15thDay
22%8%25%423345%36%
1800
16th to endDay
18%8%36%5%2435%6%34%
2213
April1st to 15thDay
14%5%25%5%34446%42%
2151
16th to endDay
17%5%35%43345%7%39%
2163
May1st to 15thDay
18%6%26%5%25%447%36%
2331
16th to endDay
10%5%26%6%45%5%6%9%37%
2439
June1st to 15thDay
8%4235%35%5%6%8%46%
2520
16th to endDay
6%3145%46%6%6%10%43%
2520
July1st to 15thDay
10%426%6%36%6%5%9%38%
2520
16th to endDay
7%3245%36%6%7%11%40%
2594
August1st to 15thDay
8%325%5%35%5%6%9%43%
2133
16th to endDay
8%325%5%35%5%5%10%43%
2100
September1st to 15thDay
11%425%6%36%6%5%7%39%
1939
16th to endDay
13%5%25%423346%48%
1815
October1st to 15thDay
13%414333337%51%
1793
16th to endDay
16%41341324452%
1669
November1st to 15thDay
13%414323345%52%
1582
16th to endDay
18%6%23223346%44%
1620
December1st to 15thDay
21%10%24414445%36%
1611
16th to endDay
20%11%25%423435%35%
1536
January1st to 15thNight
18%9%26%424435%37%
2506
16th to endNight
16%8%36%423345%39%
2508
February1st to 15thNight
21%7%46%43343436%
2103
16th to endNight
17%8%37%43435%438%
1893
March1st to 15thNight
17%9%35%424345%40%
2160
16th to endNight
17%6%36%5%2345%6%38%
2020
April1st to 15thNight
12%5%2432345%6%49%
1797
16th to endNight
14%5%2432345%7%45%
1797
May1st to 15thNight
16%5%345%3345%7%41%
1619
16th to endNight
6%4146%35%6%7%10%44%
1670
June1st to 15thNight
8%4143245%5%9%50%
1440
16th to endNight
3213435%6%7%12%49%
1440
July1st to 15thNight
8%3244346%6%9%46%
1440
16th to endNight
6%213425%5%6%10%51%
1573
August1st to 15thNight
6%2134235%6%9%52%
1738
16th to endNight
7%22432445%9%53%
1750
September1st to 15thNight
10%42432445%8%48%
1680
16th to endNight
11%5%24323446%50%
1815
October1st to 15thNight
11%5%24313335%55%
1834
16th to endNight
16%6%23313335%50%
2203
November1st to 15thNight
12%5%13322346%52%
2276
16th to endNight
18%6%2331325%5%47%
2340
December1st to 15thNight
22%9%3442335%5%35%
2346
16th to endNight
23%8%35%5%1433436%
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
50%48%23%11%1
1433
16th to endDay
46%411%27%9%1
1714
February1st to 15thDay
48%48%24%11%2
1752
16th to endDay
49%410%19%13%2
1580
March1st to 15thDay
50%49%20%12%3
1800
16th to endDay
49%5%11%24%7%
2214
April1st to 15thDay
41%49%21%20%2
2151
16th to endDay
42%5%9%26%13%2
2163
May1st to 15thDay
47%7%10%20%12%1
2331
16th to endDay
41%9%14%19%12%2
2443
June1st to 15thDay
32%7%13%25%17%2
2520
16th to endDay
32%9%13%21%19%4
2520
July1st to 15thDay
40%9%12%21%12%4
2371
16th to endDay
33%8%19%24%12%1
2432
August1st to 15thDay
35%7%13%25%16%2
2120
16th to endDay
35%8%13%22%16%4
2100
September1st to 15thDay
40%8%11%19%16%3
1939
16th to endDay
36%47%21%24%5%
1815
October1st to 15thDay
33%49%24%23%5%
1793
16th to endDay
36%45%25%23%5%
1669
November1st to 15thDay
34%38%21%24%7%
1582
16th to endDay
40%37%28%15%4
1620
December1st to 15thDay
50%411%18%12%2
1611
16th to endDay
51%411%21%9%1
1536
January1st to 15thNight
49%38%21%15%1
2506
16th to endNight
47%311%22%13%1
2508
February1st to 15thNight
51%38%22%11%1
2112
16th to endNight
48%410%22%11%2
1893
March1st to 15thNight
45%5%9%19%15%4
2160
16th to endNight
45%5%12%23%11%1
2020
April1st to 15thNight
33%5%11%24%20%5%
1797
16th to endNight
37%5%8%27%19%2
1797
May1st to 15thNight
43%411%23%15%1
1620
16th to endNight
33%9%14%22%16%3
1672
June1st to 15thNight
29%5%15%25%21%2
1440
16th to endNight
25%8%14%25%20%5%
1440
July1st to 15thNight
31%8%14%25%14%5%
1360
16th to endNight
26%7%17%29%16%2
1472
August1st to 15thNight
25%7%14%26%23%2
1727
16th to endNight
26%7%13%27%20%4
1750
September1st to 15thNight
33%6%10%24%19%5%
1680
16th to endNight
34%47%19%25%8%
1815
October1st to 15thNight
31%38%21%28%6%
1834
16th to endNight
37%25%24%23%6%
2203
November1st to 15thNight
32%35%24%24%9%
2276
16th to endNight
38%38%25%19%4
2340
December1st to 15thNight
50%310%18%13%2
2346
16th to endNight
51%49%19%12%1
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
40%20%24%8%6%
90
16th to endDay
14%32%44%7%1
96
February1st to 15thDay
22%35%34%5%2
90
16th to endDay
24%27%34%12%1
81
March1st to 15thDay
31%24%35%6%2
90
16th to endDay
17%17%34%22%7%
258
April1st to 15thDay
15%16%30%27%7%3
270
16th to endDay
18%11%26%27%12%4
270
May1st to 15thDay
20%13%25%24%9%6%
288
16th to endDay
12%7%23%30%15%10%
339
June1st to 15thDay
9%318%29%25%13%
495
16th to endDay
7%222%33%21%11%
495
July1st to 15thDay
13%117%30%25%11%
475
16th to endDay
6%9%27%31%23%
454
August1st to 15thDay
13%26%27%30%19%
297
16th to endDay
14%5%22%38%19%
268
September1st to 15thDay
9%112%22%30%21%
255
16th to endDay
18%314%22%28%12%
254
October1st to 15thDay
10%5%28%23%21%9%
233
16th to endDay
15%10%30%29%12%2
96
November1st to 15thDay
13%10%34%21%16%4
90
16th to endDay
27%17%31%15%6%1
90
December1st to 15thDay
15%18%41%16%7%
90
16th to endDay
23%28%37%8%2
96
January1st to 15thNight
26%16%31%22%4
900
16th to endNight
21%17%34%23%2
909
February1st to 15thNight
24%17%33%22%2
704
16th to endNight
22%16%38%20%1
631
March1st to 15thNight
22%15%33%24%4
720
16th to endNight
19%12%29%28%9%
647
April1st to 15thNight
14%12%35%24%12%
539
16th to endNight
16%8%30%30%13%
540
May1st to 15thNight
19%7%28%27%14%2
540
16th to endNight
9%221%33%30%3
563
June1st to 15thNight
9%15%38%31%3
540
16th to endNight
4114%40%36%3
540
July1st to 15thNight
8%111%33%39%6%
510
16th to endNight
6%19%29%40%12%
564
August1st to 15thNight
7%7%32%42%9%
527
16th to endNight
7%17%35%41%5%
525
September1st to 15thNight
12%212%27%36%8%
525
16th to endNight
12%416%30%29%6%
657
October1st to 15thNight
13%5%18%31%25%5%
660
16th to endNight
19%7%27%28%15%1
704
November1st to 15thNight
12%10%28%30%16%1
700
16th to endNight
21%12%29%25%9%
720
December1st to 15thNight
27%12%28%22%8%
726
16th to endNight
27%12%31%22%4
960
Page generated at 2017-08-13 13:16:55. Version ac04

Copyright 2017 A. Danko


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