Penitentiary Glen Reservation
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Penitentiary Glen Reservation clear sky chart from 2005-11-05 to

2017-09-12
.

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
31%
15101
12%
46900
9%
15060
36%
15060
15%
34638

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
6%
718
7%
2327
2%
716
11%
716
5%
2003
January16th to endNight
9%
768
6%
2496
1%
768
15%
768
5%
2158
February1st to 15thNight
14%
704
6%
2287
2%
701
19%
701
6%
1920
February16th to endNight
15%
631
8%
1931
3%
631
22%
631
9%
1561
March1st to 15thNight
21%
720
13%
2008
7%
720
26%
720
13%
1588
March16th to endNight
28%
768
15%
2112
9%
768
32%
768
18%
1561
April1st to 15thNight
25%
692
11%
1857
4%
692
30%
692
18%
1368
April16th to endNight
33%
540
18%
1620
8%
540
42%
540
24%
1095
May1st to 15thNight
40%
540
13%
1620
9%
540
44%
540
18%
1160
May16th to endNight
51%
501
14%
1624
13%
501
53%
501
26%
1035
June1st to 15thNight
48%
360
15%
1440
16%
360
55%
360
20%
884
June16th to endNight
53%
360
15%
1440
16%
360
60%
360
23%
863
July1st to 15thNight
59%
469
15%
1489
15%
469
63%
469
31%
888
July16th to endNight
61%
564
15%
1595
14%
531
63%
531
31%
964
August1st to 15thNight
64%
539
18%
1609
15%
536
65%
536
31%
973
August16th to endNight
62%
591
22%
1737
16%
591
65%
591
32%
1052
September1st to 15thNight
54%
707
20%
1872
13%
707
57%
707
30%
1232
September16th to endNight
49%
657
20%
1815
14%
657
53%
657
26%
1222
October1st to 15thNight
43%
660
17%
1950
15%
660
46%
660
23%
1313
October16th to endNight
18%
704
11%
2112
5%
704
26%
704
13%
1620
November1st to 15thNight
27%
700
16%
2276
12%
700
34%
700
17%
1624
November16th to endNight
14%
720
9%
2502
7%
720
18%
720
7%
2014
December1st to 15thNight
11%
720
4%
2520
3%
720
13%
720
5%
2189
December16th to endNight
7%
768
3%
2661
0%
768
11%
768
3%
2351

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
16%10%47%5%2445%6%30%
47743
Night
17%12%47%5%34446%29%
47093
Cloud CoverDay
17%11%46%5%24446%30%
47753
Night
17%11%5%7%5%34445%29%
47097
TransparencyDay
52%6%11%17%9%1
47454
Night
55%5%10%16%9%1
46900
SeeingDay
21%11%25%24%13%4
5311
Night
22%13%26%23%12%1
15105

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
20%18%7%10%8%2434414%
1611
16th to endDay
16%20%11%14%8%3324310%
1728
February1st to 15thDay
16%20%8%12%9%4323414%
1575
16th to endDay
15%16%7%11%7%2444420%
1542
March1st to 15thDay
19%16%6%9%423346%23%
1939
16th to endDay
19%11%5%6%5%24445%30%
2112
April1st to 15thDay
21%11%36%5%2445%6%29%
2101
16th to endDay
18%10%35%423345%38%
2340
May1st to 15thDay
18%7%36%5%45%45%6%32%
2331
16th to endDay
12%5%35%5%245%5%8%40%
2491
June1st to 15thDay
15%6%25%42446%7%39%
2520
16th to endDay
14%4245%25%5%6%10%38%
2520
July1st to 15thDay
11%5%24435%5%6%10%41%
2377
16th to endDay
11%4244245%7%10%41%
2465
August1st to 15thDay
8%425%6%36%6%7%10%38%
2340
16th to endDay
11%425%5%35%5%7%9%40%
2453
September1st to 15thDay
16%6%35%42445%8%37%
2005
16th to endDay
18%8%25%42345%6%37%
1815
October1st to 15thDay
22%6%25%5%24446%33%
1680
16th to endDay
29%10%35%42435%5%25%
1760
November1st to 15thDay
15%15%35%5%24436%32%
1582
16th to endDay
22%21%5%8%6%24335%16%
1456
December1st to 15thDay
20%24%11%11%5%2332311%
1440
16th to endDay
20%25%10%13%6%2222310%
1560
January1st to 15thNight
21%21%9%12%6%2322314%
2327
16th to endNight
16%21%9%12%10%3323314%
2496
February1st to 15thNight
18%16%7%12%7%4433317%
2285
16th to endNight
18%14%6%11%7%3433322%
1931
March1st to 15thNight
18%14%5%8%5%34445%25%
1996
16th to endNight
16%12%5%6%424345%32%
2112
April1st to 15thNight
20%12%46%42345%6%30%
1857
16th to endNight
13%7%36%5%345%5%7%37%
1620
May1st to 15thNight
19%7%36%5%35%46%7%30%
1620
16th to endNight
11%5%35%5%345%6%8%40%
1622
June1st to 15thNight
10%5%26%5%45%446%43%
1440
16th to endNight
9%435%5%35%7%5%9%41%
1440
July1st to 15thNight
8%425%4235%6%8%48%
1579
16th to endNight
8%4245%2445%8%46%
1703
August1st to 15thNight
8%414435%6%6%9%45%
1620
16th to endNight
11%424335%45%8%46%
1737
September1st to 15thNight
13%5%24425%5%5%6%44%
1872
16th to endNight
17%5%245%3446%6%39%
1815
October1st to 15thNight
17%6%245%3345%7%39%
1950
16th to endNight
28%8%26%5%3345%5%25%
2112
November1st to 15thNight
19%13%35%423346%31%
2276
16th to endNight
23%20%47%5%24445%18%
2502
December1st to 15thNight
22%23%8%9%5%2333313%
2520
16th to endNight
23%21%8%10%5%343449%
2661

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
20%18%7%10%8%2443415%
1611
16th to endDay
16%21%11%13%8%3323310%
1728
February1st to 15thDay
16%20%9%11%8%4232415%
1575
16th to endDay
15%16%8%11%7%2344420%
1542
March1st to 15thDay
20%16%7%8%5%22336%23%
1950
16th to endDay
19%12%5%6%424336%30%
2111
April1st to 15thDay
21%12%45%424446%29%
2101
16th to endDay
19%10%35%423335%38%
2340
May1st to 15thDay
18%8%26%6%46%446%32%
2331
16th to endDay
13%5%25%5%345%5%8%40%
2491
June1st to 15thDay
17%5%2442436%7%39%
2520
16th to endDay
14%5%24425%5%6%10%38%
2520
July1st to 15thDay
12%425%4345%6%9%41%
2377
16th to endDay
11%5%244246%6%10%41%
2465
August1st to 15thDay
9%5%25%5%36%6%7%9%38%
2340
16th to endDay
12%5%25%435%6%5%9%39%
2453
September1st to 15thDay
17%6%2442445%8%37%
2005
16th to endDay
19%8%25%42445%6%37%
1815
October1st to 15thDay
22%6%35%434346%34%
1680
16th to endDay
29%9%35%423345%25%
1760
November1st to 15thDay
15%15%35%5%24346%32%
1582
16th to endDay
22%22%6%7%5%23335%16%
1456
December1st to 15thDay
20%23%11%10%6%2332312%
1440
16th to endDay
19%25%11%13%6%1223310%
1560
January1st to 15thNight
21%20%9%12%6%2322314%
2327
16th to endNight
16%20%9%12%10%3332314%
2496
February1st to 15thNight
18%16%7%12%6%5%433317%
2278
16th to endNight
17%14%6%12%7%3443323%
1931
March1st to 15thNight
18%14%6%8%5%3444425%
2008
16th to endNight
16%12%6%6%423345%32%
2112
April1st to 15thNight
20%12%46%42345%5%30%
1857
16th to endNight
13%7%36%5%35%5%5%6%38%
1620
May1st to 15thNight
19%7%36%5%35%46%7%30%
1619
16th to endNight
12%5%35%5%335%6%8%40%
1622
June1st to 15thNight
11%5%27%5%44447%42%
1440
16th to endNight
9%5%25%5%35%6%6%9%41%
1440
July1st to 15thNight
9%4244235%6%8%48%
1579
16th to endNight
8%5%24425%5%5%8%46%
1703
August1st to 15thNight
9%3145%35%5%7%8%45%
1620
16th to endNight
11%424425%45%8%46%
1737
September1st to 15thNight
13%5%244345%5%6%44%
1872
16th to endNight
18%5%245%35%46%6%39%
1815
October1st to 15thNight
17%6%245%33448%39%
1950
16th to endNight
29%8%25%42445%5%25%
2112
November1st to 15thNight
19%13%35%424346%31%
2276
16th to endNight
22%19%47%5%23445%18%
2502
December1st to 15thNight
22%23%9%8%43333313%
2520
16th to endNight
23%21%8%10%5%433449%
2661

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
73%5%9%8%3
1612
16th to endDay
79%38%5%1
1728
February1st to 15thDay
74%46%10%3
1577
16th to endDay
66%5%10%11%4
1542
March1st to 15thDay
63%5%10%14%5%
1950
16th to endDay
55%5%8%20%8%1
2112
April1st to 15thDay
54%5%12%16%10%
2101
16th to endDay
48%5%10%18%12%4
2340
May1st to 15thDay
51%7%9%19%10%1
2331
16th to endDay
40%7%14%23%12%1
2495
June1st to 15thDay
42%6%12%24%11%1
2520
16th to endDay
39%8%13%22%15%1
2520
July1st to 15thDay
38%7%10%23%18%1
2238
16th to endDay
35%8%15%24%15%1
2310
August1st to 15thDay
37%9%14%24%13%
2327
16th to endDay
38%8%14%21%13%2
2453
September1st to 15thDay
44%7%13%21%12%1
2005
16th to endDay
45%5%11%21%14%1
1815
October1st to 15thDay
50%6%12%18%11%1
1680
16th to endDay
60%413%14%5%
1760
November1st to 15thDay
52%6%10%17%9%3
1582
16th to endDay
70%49%10%5%
1456
December1st to 15thDay
79%38%6%2
1440
16th to endDay
81%38%5%1
1560
January1st to 15thNight
76%36%9%3
2327
16th to endNight
77%38%8%2
2496
February1st to 15thNight
71%5%8%10%3
2287
16th to endNight
66%5%9%13%5%
1931
March1st to 15thNight
61%5%9%15%7%
2008
16th to endNight
53%5%9%19%9%1
2112
April1st to 15thNight
54%412%16%12%
1857
16th to endNight
44%6%10%19%14%4
1620
May1st to 15thNight
50%6%11%18%10%2
1620
16th to endNight
38%7%13%23%13%2
1624
June1st to 15thNight
41%6%9%24%16%1
1440
16th to endNight
37%8%12%22%15%2
1440
July1st to 15thNight
32%7%11%25%19%3
1489
16th to endNight
33%7%14%21%18%3
1595
August1st to 15thNight
32%8%13%27%15%1
1609
16th to endNight
34%6%12%26%16%3
1737
September1st to 15thNight
39%6%13%23%15%2
1872
16th to endNight
43%5%10%20%17%1
1815
October1st to 15thNight
44%6%13%18%16%1
1950
16th to endNight
59%5%13%16%5%
2112
November1st to 15thNight
54%411%15%10%4
2276
16th to endNight
68%48%13%4
2502
December1st to 15thNight
76%5%8%7%2
2520
16th to endNight
79%49%6%
2661

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%37%22%13%4
90
16th to endDay
36%26%30%6%1
96
February1st to 15thDay
30%33%28%7%
90
16th to endDay
24%24%41%8%
81
March1st to 15thDay
26%20%30%17%4
240
16th to endDay
27%16%30%17%7%1
288
April1st to 15thDay
26%18%27%19%7%1
270
16th to endDay
21%13%31%21%9%3
270
May1st to 15thDay
22%10%30%25%9%1
288
16th to endDay
16%6%31%26%15%4
331
June1st to 15thDay
20%328%30%14%2
315
16th to endDay
18%6%29%29%13%2
315
July1st to 15thDay
17%325%28%19%5%
305
16th to endDay
12%221%32%23%7%
326
August1st to 15thDay
12%220%33%21%8%
313
16th to endDay
15%416%29%21%12%
332
September1st to 15thDay
18%5%16%25%25%8%
299
16th to endDay
21%8%16%22%22%8%
254
October1st to 15thDay
20%11%20%27%16%3
255
16th to endDay
34%13%30%18%2
272
November1st to 15thDay
17%13%21%32%13%2
90
16th to endDay
31%28%20%15%3
63
December1st to 15thDay
31%30%18%13%33
60
16th to endDay
30%33%35%
68
January1st to 15thNight
29%26%30%10%2
720
16th to endNight
25%24%32%14%2
768
February1st to 15thNight
26%24%29%16%2
704
16th to endNight
24%20%32%19%2
631
March1st to 15thNight
23%18%32%20%3
720
16th to endNight
22%14%30%22%9%1
768
April1st to 15thNight
24%17%27%24%6%
692
16th to endNight
16%9%36%26%10%1
540
May1st to 15thNight
21%7%23%34%12%
540
16th to endNight
14%421%36%18%3
503
June1st to 15thNight
11%328%37%18%1
360
16th to endNight
10%327%39%18%
360
July1st to 15thNight
8%321%35%26%4
469
16th to endNight
10%316%37%27%3
564
August1st to 15thNight
11%214%39%27%5%
539
16th to endNight
12%315%31%33%4
591
September1st to 15thNight
16%5%17%29%27%3
707
16th to endNight
19%6%19%27%22%4
657
October1st to 15thNight
19%10%22%28%17%1
660
16th to endNight
34%15%29%17%3
704
November1st to 15thNight
25%13%30%20%9%1
700
16th to endNight
34%22%24%11%5%
720
December1st to 15thNight
35%22%26%12%3
720
16th to endNight
32%23%31%11%1
768
Page generated at 2017-09-13 07:39:22. Version ac04

Copyright 2017 A. Danko


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