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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 2017-05-24.

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%
14846
20%
45882
10%
14805
45%
14805
23%
29128

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%
718
20%
2449
7%
716
35%
716
16%
1567
January16th to endNight
15%
768
22%
2496
5%
768
36%
768
20%
1565
February1st to 15thNight
17%
704
18%
2287
4%
701
35%
701
18%
1436
February16th to endNight
14%
631
22%
1919
4%
631
35%
631
18%
1237
March1st to 15thNight
21%
720
20%
2017
7%
720
35%
720
20%
1354
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
46%
360
17%
1441
14%
360
54%
360
21%
866
June1st to 15thNight
45%
330
19%
1320
18%
330
55%
330
23%
768
June16th to endNight
57%
330
17%
1320
17%
330
64%
330
25%
758
July1st to 15thNight
55%
310
13%
1240
15%
310
58%
310
19%
787
July16th to endNight
67%
473
15%
1420
11%
440
72%
440
34%
807
August1st to 15thNight
65%
494
20%
1474
16%
491
66%
491
33%
900
August16th to endNight
61%
689
19%
1739
10%
689
62%
689
33%
1142
September1st to 15thNight
56%
660
26%
1650
14%
660
61%
660
35%
1061
September16th to endNight
53%
657
23%
1807
19%
657
57%
657
30%
1181
October1st to 15thNight
43%
660
23%
1980
18%
660
51%
660
25%
1267
October16th to endNight
32%
704
27%
2112
14%
704
49%
704
29%
1260
November1st to 15thNight
33%
700
24%
2244
13%
700
48%
700
26%
1363
November16th to endNight
26%
720
20%
2478
11%
720
40%
720
19%
1511
December1st to 15thNight
22%
720
17%
2520
6%
720
36%
720
15%
1660
December16th to endNight
17%
768
19%
2688
5%
768
35%
768
17%
1727

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%
46386
Night
14%5%2442445%7%42%
46064
Cloud CoverDay
14%5%25%5%3445%7%40%
46396
Night
14%5%25%42445%7%42%
46068
TransparencyDay
42%6%11%21%15%2
46086
Night
40%5%11%23%16%2
45882
SeeingDay
17%12%25%23%15%5%
5202
Night
17%12%31%26%11%1
14849

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%435%45%6%37%
1489
16th to endDay
14%8%26%434346%39%
1728
February1st to 15thDay
14%8%35%6%445%5%6%37%
1575
16th to endDay
13%9%36%6%33345%40%
1554
March1st to 15thDay
15%7%35%5%24347%40%
1930
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
14%5%25%5%3446%7%39%
2517
June1st to 15thDay
13%424435%5%6%10%37%
2310
16th to endDay
11%4245%25%5%6%9%42%
2310
July1st to 15thDay
9%5%25%5%35%7%6%9%39%
2310
16th to endDay
7%336%6%46%7%6%10%37%
2330
August1st to 15thDay
11%425%5%35%6%6%9%38%
2145
16th to endDay
12%425%5%335%7%7%41%
2100
September1st to 15thDay
15%41243445%7%45%
1980
16th to endDay
16%5%25%433348%42%
1821
October1st to 15thDay
18%5%23424346%44%
1650
16th to endDay
15%5%25%33335%5%45%
1760
November1st to 15thDay
13%6%2342435%6%45%
1614
16th to endDay
17%6%25%5%23446%40%
1479
December1st to 15thDay
16%6%36%5%345%5%6%36%
1440
16th to endDay
16%7%345%2335%8%37%
1536
January1st to 15thNight
16%7%36%4235%5%7%37%
2449
16th to endNight
16%6%24424346%42%
2496
February1st to 15thNight
15%7%3442445%6%41%
2285
16th to endNight
14%8%3442446%6%40%
1919
March1st to 15thNight
15%6%25%5%3435%6%41%
2005
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
11%5%25%5%2436%7%43%
1439
June1st to 15thNight
11%5%2442446%8%44%
1320
16th to endNight
8%424425%6%6%9%43%
1320
July1st to 15thNight
7%5%26%7%35%6%6%9%37%
1320
16th to endNight
6%41433447%11%46%
1527
August1st to 15thNight
8%424425%5%6%8%46%
1485
16th to endNight
11%4244245%48%46%
1739
September1st to 15thNight
11%43441435%7%48%
1650
16th to endNight
14%5%15%423436%46%
1807
October1st to 15thNight
17%6%24324445%44%
1980
16th to endNight
15%5%23323446%50%
2112
November1st to 15thNight
13%5%34424235%49%
2244
16th to endNight
15%5%244245%6%7%41%
2478
December1st to 15thNight
17%5%35%5%35%5%46%36%
2520
16th to endNight
17%6%25%5%345%5%7%37%
2688

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%345%35%45%6%37%
1489
16th to endDay
13%9%25%5%2435%6%39%
1728
February1st to 15thDay
13%7%35%6%445%5%6%37%
1575
16th to endDay
13%8%36%6%3435%6%39%
1554
March1st to 15thDay
14%7%35%5%24446%40%
1941
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%38%
2517
June1st to 15thDay
13%4245%35%5%7%10%37%
2310
16th to endDay
11%4245%35%5%5%8%42%
2310
July1st to 15thDay
9%5%26%5%36%6%6%9%39%
2310
16th to endDay
7%335%5%46%7%7%10%37%
2330
August1st to 15thDay
10%5%25%5%36%6%7%8%37%
2145
16th to endDay
11%5%25%5%35%5%6%8%40%
2100
September1st to 15thDay
15%41343445%7%45%
1980
16th to endDay
16%5%25%43335%8%41%
1821
October1st to 15thDay
18%5%23433347%44%
1650
16th to endDay
15%5%25%42435%5%45%
1760
November1st to 15thDay
13%6%2442346%6%45%
1614
16th to endDay
17%5%35%424346%40%
1479
December1st to 15thDay
16%6%35%5%35%45%6%36%
1440
16th to endDay
16%7%35%5%2345%7%37%
1536
January1st to 15thNight
17%6%36%42346%7%37%
2449
16th to endNight
16%5%345%34347%41%
2496
February1st to 15thNight
14%7%2442435%7%41%
2278
16th to endNight
14%8%3443445%6%39%
1919
March1st to 15thNight
15%5%2443445%6%41%
2017
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
11%6%25%4235%5%8%43%
1439
June1st to 15thNight
11%5%2342446%9%44%
1320
16th to endNight
7%424435%6%6%9%43%
1320
July1st to 15thNight
7%5%27%5%46%6%6%9%37%
1320
16th to endNight
6%314425%5%6%12%46%
1527
August1st to 15thNight
8%5%14435%47%8%46%
1485
16th to endNight
11%4244345%48%46%
1739
September1st to 15thNight
11%42442445%7%48%
1650
16th to endNight
14%5%25%424346%46%
1807
October1st to 15thNight
17%6%24424345%44%
1980
16th to endNight
15%413324346%49%
2112
November1st to 15thNight
13%5%35%424235%49%
2244
16th to endNight
16%4344235%6%7%41%
2478
December1st to 15thNight
17%5%35%6%35%5%46%36%
2520
16th to endNight
16%6%25%5%345%5%7%37%
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
46%412%21%11%3
1490
16th to endDay
45%412%22%11%3
1728
February1st to 15thDay
45%5%11%23%10%2
1577
16th to endDay
46%312%23%11%2
1554
March1st to 15thDay
43%312%22%15%1
1941
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
42%7%12%22%13%1
2521
June1st to 15thDay
39%8%14%24%12%
2310
16th to endDay
38%7%14%22%15%1
2310
July1st to 15thDay
39%9%12%20%14%3
2161
16th to endDay
38%9%12%22%14%2
2174
August1st to 15thDay
40%8%14%20%15%1
2132
16th to endDay
39%5%12%25%15%2
2100
September1st to 15thDay
37%6%11%19%21%2
1980
16th to endDay
42%5%8%20%20%2
1821
October1st to 15thDay
40%410%23%17%2
1650
16th to endDay
39%410%26%17%1
1760
November1st to 15thDay
38%5%12%20%17%5%
1614
16th to endDay
43%5%10%25%13%1
1479
December1st to 15thDay
46%5%14%21%10%1
1440
16th to endDay
45%414%21%12%
1536
January1st to 15thNight
45%411%21%14%3
2449
16th to endNight
42%312%26%13%1
2496
February1st to 15thNight
41%413%23%14%2
2287
16th to endNight
42%411%23%16%1
1919
March1st to 15thNight
42%5%10%26%13%1
2017
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
37%8%14%19%15%3
1441
June1st to 15thNight
36%8%12%25%16%
1320
16th to endNight
33%8%12%25%17%1
1320
July1st to 15thNight
41%9%12%20%11%3
1240
16th to endNight
29%7%19%23%18%2
1420
August1st to 15thNight
32%8%15%25%16%1
1474
16th to endNight
35%7%9%24%19%3
1739
September1st to 15thNight
35%5%11%20%23%3
1650
16th to endNight
39%5%8%19%22%3
1807
October1st to 15thNight
41%5%9%23%17%2
1980
16th to endNight
34%5%9%29%20%1
2112
November1st to 15thNight
39%38%23%18%6%
2244
16th to endNight
39%5%10%24%17%2
2478
December1st to 15thNight
47%5%12%22%11%1
2520
16th to endNight
44%5%15%22%11%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
27%31%26%13%1
69
16th to endDay
19%36%27%15%1
96
February1st to 15thDay
24%34%33%7%
90
16th to endDay
18%27%39%13%
213
March1st to 15thDay
17%24%30%22%4
270
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
17%5%21%26%22%6%
302
June1st to 15thDay
15%6%28%26%19%3
255
16th to endDay
15%6%25%29%18%5%
255
July1st to 15thDay
13%223%28%24%7%
245
16th to endDay
8%213%37%28%8%
270
August1st to 15thDay
13%215%32%26%9%
253
16th to endDay
11%10%31%25%20%
268
September1st to 15thDay
14%6%16%20%27%15%
255
16th to endDay
19%5%19%26%15%13%
254
October1st to 15thDay
18%9%20%27%18%5%
255
16th to endDay
16%13%32%24%11%1
272
November1st to 15thDay
17%9%30%21%18%1
241
16th to endDay
21%18%32%18%9%1
99
December1st to 15thDay
15%35%25%13%10%1
60
16th to endDay
20%15%45%15%3
64
January1st to 15thNight
20%19%35%20%3
720
16th to endNight
20%19%41%17%
768
February1st to 15thNight
19%20%37%21%1
704
16th to endNight
20%23%37%16%1
631
March1st to 15thNight
19%17%36%21%3
720
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
13%5%25%36%18%1
361
June1st to 15thNight
11%233%31%19%
330
16th to endNight
10%223%44%18%
330
July1st to 15thNight
10%221%39%24%
310
16th to endNight
7%16%42%28%3
473
August1st to 15thNight
9%115%49%22%1
494
16th to endNight
13%214%37%28%4
689
September1st to 15thNight
13%318%34%27%2
660
16th to endNight
15%321%31%25%3
657
October1st to 15thNight
21%7%22%28%16%2
660
16th to endNight
17%11%35%24%10%
704
November1st to 15thNight
16%12%33%27%9%1
700
16th to endNight
18%19%31%22%8%
720
December1st to 15thNight
21%14%36%19%8%
720
16th to endNight
20%17%41%19%2
768
Page generated at 2017-05-25 13:27:34. Version ac04

Copyright 2017 A. Danko


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