Barb's Ridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barb's Ridge clear sky chart from 2005-11-05 to 2018-11-30.

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
46%
16924
23%
51782
16%
16881
53%
16881
25%
31768

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
23%
780
21%
2522
10%
776
38%
776
16%
1636
January16th to endNight
30%
832
25%
2606
13%
832
42%
832
19%
1699
February1st to 15thNight
27%
764
21%
2292
10%
761
38%
761
19%
1515
February16th to endNight
25%
683
21%
2049
10%
683
35%
683
17%
1382
March1st to 15thNight
30%
780
21%
2295
13%
780
38%
780
20%
1506
March16th to endNight
33%
832
19%
2288
10%
832
40%
832
23%
1502
April1st to 15thNight
44%
584
26%
1947
19%
584
55%
584
30%
1063
April16th to endNight
46%
579
26%
1870
18%
579
57%
579
28%
1049
May1st to 15thNight
50%
585
23%
1755
15%
585
56%
585
29%
1053
May16th to endNight
54%
609
18%
1827
12%
609
59%
609
24%
1134
June1st to 15thNight
62%
585
19%
1755
14%
585
66%
585
33%
985
June16th to endNight
68%
585
19%
1755
13%
585
72%
585
37%
964
July1st to 15thNight
66%
555
15%
1665
14%
555
67%
555
30%
1010
July16th to endNight
65%
612
18%
1739
15%
579
71%
579
33%
1018
August1st to 15thNight
68%
575
19%
1815
20%
572
70%
572
30%
1061
August16th to endNight
65%
621
18%
2070
21%
621
66%
621
27%
1264
September1st to 15thNight
61%
702
19%
2067
17%
702
64%
702
28%
1300
September16th to endNight
60%
777
28%
2145
21%
777
65%
777
33%
1285
October1st to 15thNight
56%
780
33%
2145
26%
780
61%
780
35%
1250
October16th to endNight
50%
832
31%
2541
26%
832
60%
832
32%
1452
November1st to 15thNight
45%
820
28%
2666
25%
820
54%
820
27%
1552
November16th to endNight
40%
840
27%
2729
18%
840
53%
840
24%
1606
December1st to 15thNight
33%
780
22%
2535
14%
780
44%
780
18%
1615
December16th to endNight
26%
832
19%
2704
11%
832
36%
832
14%
1867

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%5%25%5%35%5%5%7%39%
52519
Night
12%5%25%42445%7%44%
51980
TransparencyDay
42%411%21%16%3
52220
Night
38%311%22%18%4
51783
SeeingDay
16%11%16%20%21%12%
6790
Night
14%19%13%26%21%4
16926

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
20%7%35%5%33345%38%
1746
16th to endDay
18%5%34424345%44%
1968
February1st to 15thDay
18%9%37%413345%37%
1900
16th to endDay
18%7%35%5%34445%36%
1710
March1st to 15thDay
17%7%25%6%24446%39%
1995
16th to endDay
16%6%35%5%25%45%6%36%
2297
April1st to 15thDay
12%5%24435%45%6%42%
2331
16th to endDay
13%5%25%5%34447%42%
2363
May1st to 15thDay
13%5%25%5%3445%6%43%
2526
16th to endDay
11%5%26%6%36%5%8%8%35%
2639
June1st to 15thDay
6%425%6%46%7%7%10%37%
2535
16th to endDay
5%3146%5%5%8%8%11%39%
2535
July1st to 15thDay
10%426%8%5%8%7%7%9%30%
2535
16th to endDay
7%425%7%5%8%7%8%11%30%
2673
August1st to 15thDay
7%5%26%7%5%6%7%8%9%31%
2384
16th to endDay
12%5%26%8%5%7%7%8%8%27%
2484
September1st to 15thDay
12%5%36%6%46%6%6%7%33%
2210
16th to endDay
13%5%245%3445%5%44%
2145
October1st to 15thDay
11%424424445%52%
2145
16th to endDay
13%5%2332233454%
2033
November1st to 15thDay
14%4245%23345%49%
1852
16th to endDay
17%5%13323346%46%
1886
December1st to 15thDay
17%8%35%5%33445%37%
1755
16th to endDay
23%9%35%433345%34%
1872
January1st to 15thNight
18%6%36%424336%40%
2522
16th to endNight
16%6%35%5%2445%6%39%
2606
February1st to 15thNight
17%7%25%5%24335%41%
2283
16th to endNight
17%7%36%43445%5%38%
2049
March1st to 15thNight
16%5%25%4235%5%6%41%
2295
16th to endNight
12%8%35%5%24447%41%
2288
April1st to 15thNight
12%31332445%7%50%
1947
16th to endNight
10%424423447%50%
1870
May1st to 15thNight
10%4245%3445%7%47%
1754
16th to endNight
8%4245%35%5%7%9%43%
1826
June1st to 15thNight
44245%25%48%11%45%
1755
16th to endNight
2313425%5%8%12%49%
1755
July1st to 15thNight
9%425%5%35%5%7%9%41%
1755
16th to endNight
43245%36%6%9%13%40%
1847
August1st to 15thNight
5%3145%36%7%7%11%42%
1826
16th to endNight
8%6%35%5%45%5%7%9%39%
2070
September1st to 15thNight
9%416%5%35%6%7%8%40%
2067
16th to endNight
9%5%2342345%6%50%
2145
October1st to 15thNight
11%323423346%55%
2145
16th to endNight
12%5%1432333454%
2541
November1st to 15thNight
13%5%24323346%49%
2666
16th to endNight
14%7%24422345%48%
2729
December1st to 15thNight
16%7%36%424446%39%
2535
16th to endNight
23%8%25%423446%34%
2704

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
48%25%19%21%2
1747
16th to endDay
42%17%24%18%4
1968
February1st to 15thDay
49%35%21%17%2
1902
16th to endDay
48%27%20%17%3
1710
March1st to 15thDay
46%37%18%18%5%
1995
16th to endDay
46%312%23%11%1
2298
April1st to 15thDay
41%310%22%18%4
2331
16th to endDay
41%38%23%18%3
2363
May1st to 15thDay
40%312%27%14%2
2526
16th to endDay
42%5%15%23%11%1
2643
June1st to 15thDay
38%5%17%24%13%
2535
16th to endDay
35%7%15%22%15%3
2535
July1st to 15thDay
43%6%16%21%8%3
2396
16th to endDay
42%6%18%21%8%1
2518
August1st to 15thDay
42%7%15%20%12%1
2371
16th to endDay
48%5%15%18%10%2
2484
September1st to 15thDay
46%6%12%17%12%4
2210
16th to endDay
40%39%22%20%3
2145
October1st to 15thDay
34%27%22%24%7%
2145
16th to endDay
33%25%22%28%8%
2033
November1st to 15thDay
38%25%18%27%7%
1852
16th to endDay
38%25%23%25%4
1886
December1st to 15thDay
49%25%22%16%4
1755
16th to endDay
53%19%18%13%2
1872
January1st to 15thNight
46%27%19%20%3
2522
16th to endNight
45%35%21%19%4
2606
February1st to 15thNight
45%27%21%17%4
2292
16th to endNight
47%37%22%17%2
2049
March1st to 15thNight
43%47%19%17%7%
2295
16th to endNight
43%211%26%14%1
2288
April1st to 15thNight
31%212%25%21%5%
1947
16th to endNight
33%210%24%23%5%
1870
May1st to 15thNight
35%413%25%19%2
1755
16th to endNight
36%7%17%23%13%2
1828
June1st to 15thNight
29%5%20%29%13%2
1755
16th to endNight
24%6%21%27%15%3
1755
July1st to 15thNight
34%6%21%21%12%3
1665
16th to endNight
30%6%24%23%12%3
1739
August1st to 15thNight
32%7%20%23%14%2
1815
16th to endNight
37%5%19%22%12%1
2070
September1st to 15thNight
38%5%19%18%14%3
2067
16th to endNight
34%39%23%24%5%
2145
October1st to 15thNight
31%39%25%21%8%
2145
16th to endNight
34%1221%28%11%
2541
November1st to 15thNight
36%25%20%25%9%
2666
16th to endNight
38%15%21%26%6%
2729
December1st to 15thNight
45%28%21%18%4
2535
16th to endNight
52%28%18%15%2
2704

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
30%19%29%14%6%
135
16th to endDay
22%20%37%11%5%2
144
February1st to 15thDay
32%22%31%14%
135
16th to endDay
36%14%38%10%
120
March1st to 15thDay
23%23%28%20%21
180
16th to endDay
22%21%23%19%11%1
352
April1st to 15thDay
17%18%22%23%14%2
330
16th to endDay
17%15%21%20%20%5%
319
May1st to 15thDay
14%16%19%20%18%10%
348
16th to endDay
18%10%13%21%19%16%
395
June1st to 15thDay
7%11%9%20%28%24%
375
16th to endDay
8%9%12%23%22%24%
375
July1st to 15thDay
11%7%6%20%25%28%
365
16th to endDay
8%8%419%30%27%
390
August1st to 15thDay
13%6%5%23%29%21%
358
16th to endDay
13%5%5%22%31%20%
396
September1st to 15thDay
13%6%8%18%32%20%
375
16th to endDay
15%5%7%22%36%12%
374
October1st to 15thDay
14%5%18%26%24%10%
375
16th to endDay
15%11%17%26%24%4
312
November1st to 15thDay
26%13%28%21%9%
180
16th to endDay
16%11%28%25%15%2
178
December1st to 15thDay
27%14%29%20%7%
135
16th to endDay
31%20%34%11%2
144
January1st to 15thNight
20%28%21%22%5%
780
16th to endNight
16%26%20%30%6%
832
February1st to 15thNight
21%25%20%28%3
764
16th to endNight
19%28%21%26%3
683
March1st to 15thNight
20%26%19%28%5%
780
16th to endNight
16%23%19%28%10%
832
April1st to 15thNight
13%21%18%29%15%
584
16th to endNight
12%20%15%32%18%1
579
May1st to 15thNight
10%18%15%29%22%3
585
16th to endNight
10%17%6%22%34%8%
611
June1st to 15thNight
415%6%22%39%11%
585
16th to endNight
415%5%22%41%10%
585
July1st to 15thNight
9%12%318%41%14%
555
16th to endNight
6%16%214%42%17%
612
August1st to 15thNight
6%10%320%47%12%
575
16th to endNight
11%8%323%45%8%
621
September1st to 15thNight
12%8%5%20%42%10%
702
16th to endNight
12%9%7%25%38%6%
777
October1st to 15thNight
13%11%12%25%29%6%
780
16th to endNight
14%13%16%30%20%3
832
November1st to 15thNight
15%18%15%30%17%3
820
16th to endNight
16%21%16%29%14%1
840
December1st to 15thNight
18%23%17%29%10%
780
16th to endNight
24%25%18%27%4
832
Page generated at 2018-12-01 10:35:31. Version ac04

Copyright 2018 A. Danko


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