Slippery Falls Boy Scout Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Slippery Falls Boy Scout Ranch clear sky chart from 2005-11-05 to 2017-03-24.

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
48%
15139
29%
45245
19%
15094
58%
15094
38%
24937

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
36%
898
31%
2327
12%
895
48%
895
39%
1344
January16th to endNight
38%
960
33%
2496
14%
960
49%
960
41%
1427
February1st to 15thNight
31%
797
26%
2205
10%
793
42%
793
33%
1303
February16th to endNight
26%
622
30%
1884
9%
622
42%
622
31%
1061
March1st to 15thNight
32%
540
26%
1980
14%
540
47%
540
25%
1133
March16th to endNight
32%
555
21%
2035
14%
555
44%
555
26%
1159
April1st to 15thNight
30%
494
24%
1791
14%
494
47%
494
28%
980
April16th to endNight
34%
495
25%
1551
14%
495
50%
495
33%
889
May1st to 15thNight
37%
495
23%
1485
14%
495
51%
495
30%
913
May16th to endNight
54%
515
24%
1540
20%
513
63%
513
39%
862
June1st to 15thNight
66%
495
25%
1485
22%
495
74%
495
50%
742
June16th to endNight
76%
495
25%
1485
24%
495
79%
495
50%
752
July1st to 15thNight
78%
465
23%
1395
24%
465
81%
465
46%
730
July16th to endNight
87%
522
30%
1468
36%
489
87%
489
57%
687
August1st to 15thNight
90%
494
36%
1475
44%
491
91%
491
55%
701
August16th to endNight
82%
525
30%
1684
35%
525
83%
525
43%
867
September1st to 15thNight
69%
495
27%
1815
31%
495
72%
495
32%
988
September16th to endNight
70%
492
35%
1815
33%
492
78%
492
42%
868
October1st to 15thNight
55%
579
33%
1899
25%
579
63%
579
38%
1006
October16th to endNight
49%
704
36%
2112
20%
704
60%
704
47%
1061
November1st to 15thNight
49%
742
31%
2142
17%
742
59%
742
44%
1121
November16th to endNight
37%
900
32%
2340
15%
900
46%
900
38%
1392
December1st to 15thNight
37%
900
30%
2340
13%
900
48%
900
37%
1394
December16th to endNight
32%
960
28%
2496
11%
960
43%
960
34%
1557

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
9%313323319%5%44%
45681
Night
8%312212318%5%49%
45441
Cloud CoverDay
11%424423446%51%
45679
Night
10%313323346%56%
45441
TransparencyDay
33%410%23%21%5%
45379
Night
28%49%24%24%9%
45246
SeeingDay
11%5%20%28%25%8%
4886
Night
11%7%28%33%16%1
15141

By Month

Percentage Cloud Cover SW (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
10%6%12212119%5%45%
1611
16th to endDay
9%212312320%447%
1728
February1st to 15thDay
10%5%13322318%345%
1666
16th to endDay
14%422212218%344%
1589
March1st to 15thDay
13%5%13312320%340%
1980
16th to endDay
12%6%13322220%340%
2033
April1st to 15thDay
11%312212222%6%42%
1825
16th to endDay
12%313212321%5%40%
2076
May1st to 15thDay
14%413422222%436%
2136
16th to endDay
8%426%433423%6%33%
2222
June1st to 15thDay
7%313424422%6%40%
2145
16th to endDay
312423323%7%46%
2145
July1st to 15thDay
5%23434417%7%46%
2145
16th to endDay
312323423%7%45%
2284
August1st to 15thDay
2133245%16%6%51%
2145
16th to endDay
5%415%434416%7%43%
2161
September1st to 15thDay
11%314423414%6%43%
1815
16th to endDay
7%313322413%6%50%
1815
October1st to 15thDay
11%43323212%351%
1719
16th to endDay
8%412212211%459%
1760
November1st to 15thDay
6%412212218%5%50%
1713
16th to endDay
11%33211119%450%
1620
December1st to 15thDay
16%413312219%438%
1620
16th to endDay
13%6%13312219%442%
1728
January1st to 15thNight
8%312212319%449%
2327
16th to endNight
7%312212219%453%
2496
February1st to 15thNight
10%413212219%446%
2195
16th to endNight
9%313212219%5%47%
1884
March1st to 15thNight
13%314322320%440%
1980
16th to endNight
9%312222320%5%44%
2035
April1st to 15thNight
8%312313222%5%43%
1791
16th to endNight
10%313212221%445%
1551
May1st to 15thNight
9%313212223%5%42%
1484
16th to endNight
4212313323%8%45%
1539
June1st to 15thNight
311212323%7%50%
1485
16th to endNight
311212321%8%53%
1485
July1st to 15thNight
3112322317%10%52%
1485
16th to endNight
212222222%7%53%
1576
August1st to 15thNight
111213415%8%58%
1485
16th to endNight
3113323415%10%50%
1684
September1st to 15thNight
9%313222314%7%47%
1815
16th to endNight
5%312323414%6%53%
1815
October1st to 15thNight
11%322212312%453%
1899
16th to endNight
9%22111211%461%
2112
November1st to 15thNight
6%32222217%5%54%
2142
16th to endNight
12%33212219%447%
2340
December1st to 15thNight
13%5%13211220%442%
2340
16th to endNight
12%413212220%443%
2496

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
12%6%23222245%54%
1611
16th to endDay
13%313323336%54%
1728
February1st to 15thDay
12%6%2432342453%
1666
16th to endDay
17%5%2321223453%
1589
March1st to 15thDay
15%5%34323345%46%
1980
16th to endDay
18%8%2442433443%
2031
April1st to 15thDay
14%41332335%7%50%
1825
16th to endDay
15%424324346%49%
2076
May1st to 15thDay
18%5%25%5%24345%42%
2136
16th to endDay
12%6%26%5%3445%6%40%
2222
June1st to 15thDay
8%414435%5%5%7%49%
2145
16th to endDay
7%213435%46%8%51%
2145
July1st to 15thDay
8%314445%6%7%9%44%
2145
16th to endDay
4213425%5%6%9%54%
2284
August1st to 15thDay
2114435%5%6%8%56%
2145
16th to endDay
6%415%435%5%7%9%46%
2161
September1st to 15thDay
13%32442445%6%47%
1815
16th to endDay
8%3133225%47%56%
1815
October1st to 15thDay
12%41332334456%
1719
16th to endDay
9%41221232465%
1760
November1st to 15thDay
7%423313346%58%
1713
16th to endDay
14%313311125%60%
1620
December1st to 15thDay
18%5%23312335%50%
1620
16th to endDay
17%7%23313325%49%
1728
January1st to 15thNight
10%412313335%59%
2327
16th to endNight
9%413213345%60%
2496
February1st to 15thNight
13%42331333455%
2195
16th to endNight
12%423322336%54%
1884
March1st to 15thNight
15%325%423345%49%
1980
16th to endNight
14%424323446%49%
2035
April1st to 15thNight
10%42342435%7%51%
1791
16th to endNight
12%424322345%54%
1551
May1st to 15thNight
13%42431335%7%48%
1484
16th to endNight
8%31332445%9%53%
1539
June1st to 15thNight
411222345%9%61%
1485
16th to endNight
5%1113134410%61%
1485
July1st to 15thNight
42123335%6%12%54%
1485
16th to endNight
211231335%10%64%
1576
August1st to 15thNight
112146%6%10%62%
1485
16th to endNight
42133245%7%10%54%
1684
September1st to 15thNight
11%42332335%7%52%
1815
16th to endNight
6%3123135%5%6%60%
1815
October1st to 15thNight
12%322222335%58%
1899
16th to endNight
10%2221123467%
2112
November1st to 15thNight
7%312223336%62%
2142
16th to endNight
14%41331223457%
2340
December1st to 15thNight
14%41222235%5%55%
2340
16th to endNight
16%5%23323235%52%
2496

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
33%26%22%28%6%
1612
16th to endDay
32%37%23%27%7%
1728
February1st to 15thDay
35%37%23%23%6%
1667
16th to endDay
37%26%23%22%8%
1589
March1st to 15thDay
40%38%20%18%8%
1980
16th to endDay
45%48%19%18%4
2033
April1st to 15thDay
33%5%11%22%19%8%
1825
16th to endDay
36%5%8%22%21%6%
2076
May1st to 15thDay
43%5%10%16%19%4
2136
16th to endDay
41%6%13%20%15%1
2226
June1st to 15thDay
32%7%14%24%20%1
2145
16th to endDay
27%7%13%25%22%3
2145
July1st to 15thDay
31%7%17%28%14%
2006
16th to endDay
22%6%16%29%22%2
2129
August1st to 15thDay
21%5%15%27%26%3
2131
16th to endDay
31%7%14%30%13%3
2161
September1st to 15thDay
35%6%12%21%14%9%
1815
16th to endDay
26%49%24%24%9%
1815
October1st to 15thDay
31%39%22%20%12%
1719
16th to endDay
24%28%20%30%12%
1760
November1st to 15thDay
27%39%25%24%7%
1713
16th to endDay
29%25%19%30%11%
1620
December1st to 15thDay
37%28%26%20%3
1620
16th to endDay
39%26%21%23%5%
1728
January1st to 15thNight
28%37%21%30%9%
2327
16th to endNight
28%27%21%30%9%
2496
February1st to 15thNight
33%37%24%23%8%
2205
16th to endNight
31%38%24%21%9%
1884
March1st to 15thNight
37%47%19%20%10%
1980
16th to endNight
34%6%11%22%20%5%
2035
April1st to 15thNight
33%410%19%18%13%
1791
16th to endNight
32%48%22%23%9%
1551
May1st to 15thNight
36%5%12%17%19%8%
1485
16th to endNight
26%7%18%29%14%4
1541
June1st to 15thNight
19%5%13%33%24%4
1485
16th to endNight
20%5%14%27%25%7%
1485
July1st to 15thNight
22%5%15%35%18%2
1395
16th to endNight
15%414%32%29%3
1468
August1st to 15thNight
14%6%12%30%28%8%
1475
16th to endNight
22%7%11%31%22%5%
1684
September1st to 15thNight
32%410%21%20%10%
1815
16th to endNight
23%47%25%27%11%
1815
October1st to 15thNight
28%310%20%21%15%
1899
16th to endNight
22%25%20%31%17%
2112
November1st to 15thNight
24%28%26%26%12%
2142
16th to endNight
31%25%19%29%11%
2340
December1st to 15thNight
31%29%25%22%7%
2340
16th to endNight
36%28%20%24%8%
2496

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%13%38%17%42
90
16th to endDay
16%7%40%22%11%1
96
February1st to 15thDay
13%11%46%20%8%
90
16th to endDay
19%14%39%20%22
81
March1st to 15thDay
22%22%28%21%41
90
16th to endDay
18%14%30%21%9%5%
75
April1st to 15thDay
18%10%26%29%14%
64
16th to endDay
17%11%36%22%9%1
306
May1st to 15thDay
18%12%32%26%7%2
393
16th to endDay
16%5%29%28%17%2
437
June1st to 15thDay
9%219%34%25%8%
420
16th to endDay
7%215%32%30%11%
420
July1st to 15thDay
8%114%36%31%8%
400
16th to endDay
4421%50%17%
445
August1st to 15thDay
3334%44%14%
418
16th to endDay
10%6%31%39%12%
329
September1st to 15thDay
25%27%40%24%
90
16th to endDay
8%7%33%27%22%
90
October1st to 15thDay
7%214%37%31%6%
90
16th to endDay
13%5%20%34%23%2
96
November1st to 15thDay
13%8%18%27%27%3
90
16th to endDay
30%11%34%17%33
90
December1st to 15thDay
16%10%34%23%14%1
90
16th to endDay
19%13%47%15%3
96
January1st to 15thNight
12%14%34%31%7%
900
16th to endNight
11%10%37%33%7%
960
February1st to 15thNight
16%12%37%29%4
797
16th to endNight
15%14%42%24%3
622
March1st to 15thNight
15%13%37%29%4
540
16th to endNight
15%10%39%27%5%
555
April1st to 15thNight
12%12%42%26%5%
494
16th to endNight
15%7%41%26%8%
495
May1st to 15thNight
13%8%37%29%9%1
495
16th to endNight
7%330%35%20%2
515
June1st to 15thNight
5%123%42%23%2
495
16th to endNight
5%14%47%26%5%
495
July1st to 15thNight
5%10%46%35%1
465
16th to endNight
3438%48%4
522
August1st to 15thNight
2340%47%5%
494
16th to endNight
46%40%40%6%
525
September1st to 15thNight
11%210%36%37%2
495
16th to endNight
7%16%36%33%5%
492
October1st to 15thNight
13%324%33%22%3
579
16th to endNight
11%7%31%33%15%1
704
November1st to 15thNight
8%8%31%34%16%
742
16th to endNight
16%10%33%28%10%
900
December1st to 15thNight
18%11%31%31%7%
900
16th to endNight
19%9%35%27%7%
960
Page generated at 2017-03-25 11:39:51. Version ac04

Copyright 2017 A. Danko


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