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Bear Branch Nature Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bear Branch Nature Center clear sky chart from 2005-11-05 to 2018-03-11.

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
34%
15864
20%
49124
10%
15823
45%
15823
23%
31123

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
19%
778
20%
2654
7%
776
36%
776
17%
1677
January16th to endNight
15%
832
22%
2704
6%
832
36%
832
20%
1693
February1st to 15thNight
17%
764
18%
2482
4%
761
34%
761
17%
1584
February16th to endNight
13%
683
22%
2077
4%
683
34%
683
17%
1358
March1st to 15thNight
21%
764
21%
2141
7%
764
35%
764
21%
1428
March16th to endNight
20%
768
20%
2081
7%
768
32%
768
23%
1397
April1st to 15thNight
21%
718
18%
1796
4%
718
29%
718
26%
1219
April16th to endNight
35%
720
18%
1800
6%
720
40%
720
29%
1207
May1st to 15thNight
35%
524
17%
1604
9%
524
42%
524
21%
1088
May16th to endNight
45%
374
17%
1497
13%
374
53%
374
20%
907
June1st to 15thNight
48%
360
18%
1440
17%
360
57%
360
24%
827
June16th to endNight
55%
360
17%
1440
17%
360
63%
360
25%
827
July1st to 15thNight
55%
340
12%
1360
14%
340
58%
340
18%
873
July16th to endNight
67%
511
16%
1542
13%
478
72%
478
34%
872
August1st to 15thNight
64%
539
19%
1609
15%
536
65%
536
31%
996
August16th to endNight
61%
752
21%
1898
12%
752
63%
752
34%
1236
September1st to 15thNight
55%
720
25%
1800
13%
720
60%
720
34%
1158
September16th to endNight
55%
717
26%
1972
21%
717
59%
717
31%
1269
October1st to 15thNight
43%
720
21%
2160
17%
720
51%
720
25%
1389
October16th to endNight
33%
768
29%
2304
16%
768
50%
768
30%
1364
November1st to 15thNight
33%
760
23%
2436
12%
760
48%
760
26%
1480
November16th to endNight
27%
780
22%
2685
12%
780
42%
780
21%
1606
December1st to 15thNight
22%
780
16%
2730
5%
780
36%
780
15%
1802
December16th to endNight
17%
832
19%
2912
5%
832
35%
832
17%
1866

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
14%6%25%5%3445%7%40%
49499
Night
14%5%2442445%7%42%
49306
Cloud CoverDay
14%5%25%5%3445%7%40%
49509
Night
14%5%2442445%7%42%
49310
TransparencyDay
42%6%11%22%15%2
49199
Night
40%5%11%23%16%2
49124
SeeingDay
17%12%26%23%15%5%
6198
Night
17%11%31%26%11%1
15867

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
15%8%35%425%45%7%37%
1614
16th to endDay
13%8%26%434446%39%
1872
February1st to 15thDay
14%8%35%6%345%5%6%36%
1710
16th to endDay
15%8%36%6%33345%39%
1682
March1st to 15thDay
15%7%35%5%24446%41%
2043
16th to endDay
17%5%36%5%34445%38%
2142
April1st to 15thDay
16%6%34425%45%6%40%
2152
16th to endDay
16%5%25%33345%443%
2160
May1st to 15thDay
17%6%25%5%3446%8%35%
2354
16th to endDay
15%6%25%5%3446%7%38%
2618
June1st to 15thDay
12%424435%5%6%10%38%
2520
16th to endDay
11%4245%25%5%6%9%42%
2520
July1st to 15thDay
9%425%5%36%6%6%9%39%
2520
16th to endDay
7%335%6%46%7%6%10%37%
2516
August1st to 15thDay
11%425%6%35%6%6%9%37%
2340
16th to endDay
11%425%5%345%7%7%41%
2292
September1st to 15thDay
16%41343445%7%44%
2160
16th to endDay
14%5%25%5%33347%42%
1986
October1st to 15thDay
18%5%24424346%43%
1800
16th to endDay
14%5%2433335%6%46%
1920
November1st to 15thDay
13%7%2442435%6%45%
1752
16th to endDay
16%6%25%5%23446%43%
1602
December1st to 15thDay
16%6%36%5%35%5%5%6%37%
1560
16th to endDay
15%7%346%2345%8%37%
1664
January1st to 15thNight
16%7%35%42345%7%38%
2654
16th to endNight
15%7%24424346%42%
2704
February1st to 15thNight
15%7%35%42445%6%40%
2480
16th to endNight
15%8%3442445%6%38%
2077
March1st to 15thNight
15%6%245%3435%6%42%
2129
16th to endNight
15%6%25%5%24348%41%
2081
April1st to 15thNight
14%6%245%2446%8%39%
1796
16th to endNight
15%4245%2446%6%43%
1800
May1st to 15thNight
18%5%3442445%6%38%
1604
16th to endNight
12%6%25%42436%7%42%
1495
June1st to 15thNight
11%5%2442446%8%45%
1440
16th to endNight
8%424425%6%6%10%43%
1440
July1st to 15thNight
7%427%7%45%6%7%9%36%
1440
16th to endNight
7%41433447%10%47%
1649
August1st to 15thNight
9%4245%25%5%6%8%45%
1620
16th to endNight
11%4145%245%48%47%
1898
September1st to 15thNight
12%43441445%7%48%
1800
16th to endNight
13%5%14433436%48%
1972
October1st to 15thNight
17%6%24324445%44%
2160
16th to endNight
14%5%23322346%50%
2304
November1st to 15thNight
14%5%34424235%48%
2436
16th to endNight
14%5%2442445%6%43%
2685
December1st to 15thNight
16%6%35%5%36%5%5%6%35%
2730
16th to endNight
16%7%25%5%345%5%7%37%
2912

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
15%7%3443445%6%38%
1614
16th to endDay
13%9%25%5%2435%6%39%
1872
February1st to 15thDay
14%7%35%5%345%5%6%36%
1710
16th to endDay
15%8%36%5%34346%38%
1682
March1st to 15thDay
14%6%35%5%24446%41%
2054
16th to endDay
16%6%37%5%34345%38%
2141
April1st to 15thDay
15%6%34425%45%7%40%
2152
16th to endDay
17%5%25%43345%5%43%
2160
May1st to 15thDay
16%5%26%5%25%5%6%8%35%
2354
16th to endDay
15%5%25%5%3436%8%37%
2618
June1st to 15thDay
13%424435%5%7%10%38%
2520
16th to endDay
11%4245%345%6%9%43%
2520
July1st to 15thDay
9%426%5%36%6%6%9%38%
2520
16th to endDay
7%335%5%46%7%7%10%37%
2516
August1st to 15thDay
11%5%26%5%35%6%7%8%37%
2340
16th to endDay
11%425%5%35%5%6%8%41%
2292
September1st to 15thDay
16%41343445%7%44%
2160
16th to endDay
14%5%25%43335%8%42%
1986
October1st to 15thDay
18%5%235%33347%43%
1800
16th to endDay
14%5%25%42435%5%46%
1920
November1st to 15thDay
13%6%2442346%6%44%
1752
16th to endDay
16%5%35%424346%43%
1602
December1st to 15thDay
16%6%35%5%35%45%6%37%
1560
16th to endDay
15%6%35%5%2445%7%37%
1664
January1st to 15thNight
16%6%36%42345%7%39%
2654
16th to endNight
16%6%245%34347%42%
2704
February1st to 15thNight
14%7%3443445%7%40%
2473
16th to endNight
15%8%3443445%6%38%
2077
March1st to 15thNight
15%5%2443445%5%42%
2141
16th to endNight
15%6%35%5%34338%41%
2081
April1st to 15thNight
13%6%245%3446%7%39%
1796
16th to endNight
15%5%25%42445%7%43%
1800
May1st to 15thNight
17%5%35%425%45%6%37%
1603
16th to endNight
12%6%25%42345%8%43%
1495
June1st to 15thNight
10%5%23425%46%8%45%
1440
16th to endNight
7%424435%6%6%10%43%
1440
July1st to 15thNight
7%5%27%5%46%6%6%9%36%
1440
16th to endNight
6%314425%5%6%11%47%
1649
August1st to 15thNight
9%5%14435%5%7%8%45%
1620
16th to endNight
11%4244345%48%47%
1898
September1st to 15thNight
12%425%42445%7%48%
1800
16th to endNight
13%5%24424346%47%
1972
October1st to 15thNight
17%6%24424345%44%
2160
16th to endNight
14%413214347%50%
2304
November1st to 15thNight
13%5%25%424246%47%
2436
16th to endNight
15%4244235%5%6%43%
2685
December1st to 15thNight
16%5%35%6%36%5%5%6%35%
2730
16th to endNight
16%7%25%5%345%5%7%37%
2912

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
45%412%21%12%3
1615
16th to endDay
45%412%22%12%3
1872
February1st to 15thDay
46%6%11%23%10%2
1712
16th to endDay
47%311%23%11%2
1682
March1st to 15thDay
43%312%22%16%1
2054
16th to endDay
47%49%18%16%2
2142
April1st to 15thDay
43%411%20%16%3
2152
16th to endDay
41%5%8%18%20%4
2160
May1st to 15thDay
46%6%11%20%14%1
2354
16th to endDay
44%7%12%21%12%1
2622
June1st to 15thDay
38%8%14%24%13%
2520
16th to endDay
37%7%14%22%15%1
2520
July1st to 15thDay
39%9%12%20%15%2
2371
16th to endDay
37%9%13%22%14%2
2360
August1st to 15thDay
40%8%13%19%16%1
2327
16th to endDay
38%6%12%24%15%2
2292
September1st to 15thDay
38%5%11%20%21%2
2160
16th to endDay
41%5%8%22%20%2
1986
October1st to 15thDay
42%410%23%17%2
1800
16th to endDay
38%49%27%19%1
1920
November1st to 15thDay
39%5%12%21%16%5%
1752
16th to endDay
41%5%10%26%14%1
1602
December1st to 15thDay
46%5%13%21%10%1
1560
16th to endDay
44%5%15%21%12%
1664
January1st to 15thNight
44%311%21%15%4
2654
16th to endNight
42%311%27%13%1
2704
February1st to 15thNight
42%5%13%22%13%2
2482
16th to endNight
44%410%23%16%2
2077
March1st to 15thNight
42%5%10%25%14%1
2141
16th to endNight
43%411%21%16%2
2081
April1st to 15thNight
41%412%20%17%3
1796
16th to endNight
39%5%10%19%18%6%
1800
May1st to 15thNight
45%6%10%20%14%2
1604
16th to endNight
38%8%14%19%15%3
1497
June1st to 15thNight
35%8%12%27%16%
1440
16th to endNight
33%9%12%25%17%2
1440
July1st to 15thNight
41%10%13%19%11%3
1360
16th to endNight
29%7%19%23%18%2
1542
August1st to 15thNight
33%8%14%24%16%2
1609
16th to endNight
35%7%10%25%19%3
1898
September1st to 15thNight
35%5%11%20%22%3
1800
16th to endNight
37%5%8%21%22%3
1972
October1st to 15thNight
41%5%10%23%17%2
2160
16th to endNight
33%48%30%19%1
2304
November1st to 15thNight
39%39%23%18%5%
2436
16th to endNight
38%410%25%18%2
2685
December1st to 15thNight
47%5%12%22%11%1
2730
16th to endNight
43%5%15%22%11%1
2912

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
23%31%27%14%2
104
16th to endDay
18%34%31%14%1
144
February1st to 15thDay
27%33%33%5%
135
16th to endDay
24%23%38%11%1
263
March1st to 15thDay
18%25%30%21%3
312
16th to endDay
18%19%35%19%42
288
April1st to 15thDay
21%15%32%18%10%1
270
16th to endDay
21%11%28%17%16%4
270
May1st to 15thDay
25%18%25%16%11%2
288
16th to endDay
18%6%22%26%20%5%
331
June1st to 15thDay
14%7%29%23%20%4
315
16th to endDay
14%8%28%29%14%4
315
July1st to 15thDay
13%126%30%21%6%
305
16th to endDay
8%315%35%28%9%
326
August1st to 15thDay
14%216%30%24%9%
313
16th to endDay
11%12%33%24%17%
332
September1st to 15thDay
15%8%17%20%24%13%
315
16th to endDay
16%6%17%26%19%13%
314
October1st to 15thDay
20%7%19%26%17%7%
315
16th to endDay
15%15%31%22%12%2
336
November1st to 15thDay
18%8%30%23%16%1
289
16th to endDay
17%19%36%16%9%
132
December1st to 15thDay
15%31%27%15%8%1
90
16th to endDay
15%22%43%12%5%
96
January1st to 15thNight
20%19%36%20%3
780
16th to endNight
20%18%41%18%1
832
February1st to 15thNight
19%20%37%20%1
764
16th to endNight
21%22%37%15%1
683
March1st to 15thNight
19%17%37%21%3
764
16th to endNight
17%15%43%17%5%
768
April1st to 15thNight
17%18%39%19%4
718
16th to endNight
17%12%32%26%10%1
720
May1st to 15thNight
18%9%32%28%10%
524
16th to endNight
15%5%24%35%17%1
375
June1st to 15thNight
10%131%33%20%1
360
16th to endNight
9%225%43%17%
360
July1st to 15thNight
10%220%40%24%
340
16th to endNight
7%16%42%28%3
511
August1st to 15thNight
11%114%47%23%1
539
16th to endNight
12%215%37%28%3
752
September1st to 15thNight
13%319%34%26%2
720
16th to endNight
14%320%29%27%5%
717
October1st to 15thNight
21%7%21%28%16%3
720
16th to endNight
17%11%35%23%12%
768
November1st to 15thNight
16%11%33%27%9%1
760
16th to endNight
17%18%32%23%7%
780
December1st to 15thNight
20%14%37%18%8%
780
16th to endNight
19%17%40%19%1
832
Page generated at 2018-03-12 13:28:09. Version ac04

Copyright 2018 A. Danko


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