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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 2017-09-10.

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%
15136
20%
46814
10%
15095
45%
15095
23%
29704

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
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%
700
25%
1750
13%
700
60%
700
34%
1127
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%
47808
Night
14%5%2442445%7%42%
46996
Cloud CoverDay
14%5%25%5%3445%7%40%
47818
Night
14%5%25%42445%7%42%
47000
TransparencyDay
42%6%12%21%15%2
47508
Night
40%5%11%23%16%2
46814
SeeingDay
17%11%25%23%15%5%
5630
Night
17%12%31%26%11%1
15139

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
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%412434447%45%
2098
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
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%43431435%7%48%
1750
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%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%45%
2098
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
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%42432345%7%48%
1750
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
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
2098
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
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%21%22%3
1750
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
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%9%17%20%23%13%
294
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
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
14%319%34%26%2
700
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 2017-09-11 19:35:16. Version ac04

Copyright 2017 A. Danko


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