Raven Run Nature Conservancy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Raven Run Nature Conservancy clear sky chart from 2005-11-05 to 2018-10-08.

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
45%
16791
20%
50954
14%
16747
50%
16747
24%
33450

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
21%
780
14%
2522
7%
776
29%
776
13%
1883
January16th to endNight
24%
832
17%
2704
10%
832
32%
832
16%
1882
February1st to 15thNight
21%
764
13%
2324
6%
761
29%
761
17%
1687
February16th to endNight
17%
683
14%
2049
6%
683
25%
683
15%
1526
March1st to 15thNight
27%
780
17%
2259
9%
780
33%
780
18%
1595
March16th to endNight
33%
832
14%
2288
8%
832
38%
832
20%
1628
April1st to 15thNight
36%
636
22%
1999
14%
636
46%
636
27%
1242
April16th to endNight
40%
579
20%
1776
12%
579
47%
579
24%
1186
May1st to 15thNight
42%
585
15%
1755
10%
585
46%
585
21%
1234
May16th to endNight
61%
610
18%
1828
14%
609
63%
609
26%
1189
June1st to 15thNight
70%
585
18%
1755
16%
585
72%
585
37%
999
June16th to endNight
69%
585
18%
1658
15%
585
71%
585
34%
1010
July1st to 15thNight
65%
555
15%
1613
14%
555
66%
555
29%
1032
July16th to endNight
75%
612
20%
1739
17%
579
77%
579
34%
1040
August1st to 15thNight
75%
575
22%
1715
20%
572
77%
572
35%
1018
August16th to endNight
75%
621
22%
2016
24%
621
75%
621
34%
1125
September1st to 15thNight
64%
728
23%
2093
20%
728
66%
728
30%
1327
September16th to endNight
61%
777
27%
2145
23%
777
64%
777
34%
1316
October1st to 15thNight
59%
752
31%
2101
26%
752
64%
752
38%
1236
October16th to endNight
43%
768
27%
2370
21%
768
52%
768
28%
1463
November1st to 15thNight
46%
760
27%
2471
23%
760
54%
760
30%
1437
November16th to endNight
36%
780
23%
2535
17%
780
45%
780
24%
1606
December1st to 15thNight
31%
780
14%
2535
8%
780
37%
780
16%
1788
December16th to endNight
23%
832
16%
2704
8%
832
33%
832
14%
2001

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%7%35%5%3445%7%37%
52150
Night
14%6%35%5%2445%7%40%
51147
Cloud CoverDay
14%7%35%5%3445%7%37%
52160
Night
13%7%35%5%3445%7%40%
51151
TransparencyDay
45%6%11%21%13%2
51861
Night
42%6%11%21%15%3
50954
SeeingDay
17%6%21%22%19%12%
6792
Night
17%7%23%29%19%2
16792

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
20%8%49%6%24446%28%
1746
16th to endDay
16%11%5%7%5%34335%32%
1872
February1st to 15thDay
17%11%49%5%2444429%
1864
16th to endDay
18%10%47%5%3445%6%28%
1710
March1st to 15thDay
22%8%35%5%23345%34%
2020
16th to endDay
20%8%35%5%3445%6%31%
2288
April1st to 15thDay
15%6%35%5%3445%6%39%
2289
16th to endDay
16%6%35%43445%7%38%
2459
May1st to 15thDay
20%6%25%5%3445%6%34%
2526
16th to endDay
9%7%26%6%35%5%5%8%38%
2639
June1st to 15thDay
8%425%5%45%6%6%8%41%
2535
16th to endDay
7%5%245%46%6%6%9%40%
2620
July1st to 15thDay
12%6%25%5%35%6%6%9%36%
2577
16th to endDay
10%5%25%6%47%6%7%9%34%
2673
August1st to 15thDay
10%5%246%35%5%7%9%38%
2487
16th to endDay
8%6%35%6%46%5%6%9%38%
2535
September1st to 15thDay
14%5%25%435%6%5%8%38%
2184
16th to endDay
15%5%25%423346%46%
2145
October1st to 15thDay
11%41443335%6%50%
2029
16th to endDay
18%7%14313335%47%
1853
November1st to 15thDay
14%5%24424346%47%
1717
16th to endDay
16%9%35%322335%43%
1755
December1st to 15thDay
22%10%45%42433432%
1755
16th to endDay
19%13%47%423446%30%
1872
January1st to 15thNight
17%10%49%6%4444428%
2522
16th to endNight
17%9%47%5%2444435%
2704
February1st to 15thNight
20%9%48%42335%6%31%
2322
16th to endNight
18%12%48%6%34346%28%
2049
March1st to 15thNight
17%9%46%5%33445%36%
2247
16th to endNight
16%8%46%6%34346%35%
2288
April1st to 15thNight
14%5%2442345%7%44%
1999
16th to endNight
13%7%35%5%35%45%6%40%
1776
May1st to 15thNight
16%7%35%6%245%6%7%34%
1755
16th to endNight
8%4246%36%6%7%10%39%
1826
June1st to 15thNight
5%4234245%8%12%47%
1755
16th to endNight
5%324435%5%8%12%44%
1658
July1st to 15thNight
8%425%5%3445%8%44%
1703
16th to endNight
5%314436%6%8%11%45%
1847
August1st to 15thNight
5%3145%3447%8%50%
1726
16th to endNight
5%3135%3446%10%49%
2016
September1st to 15thNight
12%4244345%5%8%44%
2093
16th to endNight
10%5%25%424346%50%
2145
October1st to 15thNight
9%5%14323448%52%
2101
16th to endNight
16%5%245%13346%46%
2370
November1st to 15thNight
14%5%24413246%49%
2471
16th to endNight
17%7%25%413346%42%
2535
December1st to 15thNight
21%9%35%43435%5%32%
2535
16th to endNight
21%11%47%5%24345%28%
2704

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%8%49%6%24446%28%
1746
16th to endDay
17%11%6%7%5%33335%32%
1872
February1st to 15thDay
18%10%5%9%5%2444429%
1864
16th to endDay
17%11%46%6%3445%5%28%
1710
March1st to 15thDay
22%9%26%424345%34%
2031
16th to endDay
20%8%35%5%3445%6%32%
2287
April1st to 15thDay
15%6%35%5%34446%39%
2289
16th to endDay
16%6%25%43445%7%39%
2459
May1st to 15thDay
19%6%36%5%25%447%34%
2526
16th to endDay
10%6%26%6%35%5%5%8%38%
2639
June1st to 15thDay
9%425%6%45%5%6%8%41%
2535
16th to endDay
7%4245%46%6%7%9%40%
2620
July1st to 15thDay
12%6%26%5%35%6%6%8%37%
2577
16th to endDay
10%425%6%46%7%7%10%34%
2673
August1st to 15thDay
9%5%25%6%45%6%7%8%38%
2487
16th to endDay
9%5%26%5%46%5%7%9%37%
2535
September1st to 15thDay
14%5%25%5%35%5%5%8%38%
2184
16th to endDay
15%5%24432346%46%
2145
October1st to 15thDay
11%41442335%6%50%
2029
16th to endDay
18%6%24313335%47%
1853
November1st to 15thDay
14%5%24424436%47%
1717
16th to endDay
16%9%25%323335%43%
1755
December1st to 15thDay
21%10%46%424345%32%
1755
16th to endDay
19%13%46%5%23445%30%
1872
January1st to 15thNight
18%9%49%7%3444428%
2522
16th to endNight
17%9%5%6%5%2334435%
2704
February1st to 15thNight
20%9%47%5%23347%31%
2315
16th to endNight
19%12%38%5%34246%28%
2049
March1st to 15thNight
17%9%35%5%24345%36%
2259
16th to endNight
16%8%36%5%34346%36%
2288
April1st to 15thNight
13%6%25%42345%7%44%
1999
16th to endNight
13%6%35%6%34446%40%
1776
May1st to 15thNight
16%7%36%5%245%6%7%34%
1754
16th to endNight
8%4146%35%5%7%10%39%
1826
June1st to 15thNight
5%4233246%8%12%47%
1755
16th to endNight
5%324435%5%8%13%43%
1658
July1st to 15thNight
8%425%5%345%5%9%44%
1703
16th to endNight
6%224436%6%7%11%45%
1847
August1st to 15thNight
5%3145%3446%9%49%
1726
16th to endNight
43244345%6%10%49%
2016
September1st to 15thNight
12%4244336%5%8%44%
2093
16th to endNight
10%425%423336%50%
2145
October1st to 15thNight
9%414323349%51%
2101
16th to endNight
16%5%145%13346%46%
2370
November1st to 15thNight
13%5%24322346%49%
2471
16th to endNight
17%7%34423337%42%
2535
December1st to 15thNight
20%9%35%434446%32%
2535
16th to endNight
20%12%47%5%34345%29%
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
57%5%8%17%11%1
1747
16th to endDay
53%49%22%8%1
1872
February1st to 15thDay
57%5%7%20%7%1
1866
16th to endDay
55%5%10%18%8%
1710
March1st to 15thDay
52%311%17%13%1
2031
16th to endDay
51%5%11%21%8%
2288
April1st to 15thDay
44%5%10%23%13%2
2289
16th to endDay
44%5%10%20%14%4
2459
May1st to 15thDay
49%6%12%20%10%1
2526
16th to endDay
41%9%14%21%11%1
2643
June1st to 15thDay
37%8%14%24%14%1
2535
16th to endDay
36%10%12%19%17%2
2620
July1st to 15thDay
41%9%13%17%14%3
2438
16th to endDay
40%10%14%21%11%2
2518
August1st to 15thDay
39%8%13%21%14%1
2474
16th to endDay
40%8%12%21%14%3
2535
September1st to 15thDay
42%7%14%15%15%4
2184
16th to endDay
39%48%22%22%2
2145
October1st to 15thDay
34%5%9%25%22%3
2029
16th to endDay
40%49%25%18%2
1853
November1st to 15thDay
38%47%24%19%5%
1717
16th to endDay
44%37%23%19%1
1755
December1st to 15thDay
54%410%18%9%1
1755
16th to endDay
55%5%11%19%7%
1872
January1st to 15thNight
58%5%7%13%13%2
2522
16th to endNight
52%39%21%11%1
2704
February1st to 15thNight
53%411%19%9%1
2324
16th to endNight
57%410%17%9%1
2049
March1st to 15thNight
50%48%19%14%2
2259
16th to endNight
49%6%11%21%9%1
2288
April1st to 15thNight
38%5%10%22%19%3
1999
16th to endNight
43%6%9%19%15%5%
1776
May1st to 15thNight
46%8%10%21%9%2
1755
16th to endNight
36%10%14%20%14%3
1828
June1st to 15thNight
26%9%16%27%15%3
1755
16th to endNight
29%10%17%22%16%4
1658
July1st to 15thNight
36%8%13%20%17%4
1613
16th to endNight
28%10%15%25%16%2
1739
August1st to 15thNight
29%8%15%23%19%3
1715
16th to endNight
28%7%14%25%20%3
2016
September1st to 15thNight
35%8%12%20%17%5%
2093
16th to endNight
34%5%8%22%26%2
2145
October1st to 15thNight
30%5%10%26%21%5%
2101
16th to endNight
39%47%23%21%3
2370
November1st to 15thNight
36%37%23%23%5%
2471
16th to endNight
43%38%24%19%1
2535
December1st to 15thNight
52%410%18%11%1
2535
16th to endNight
57%49%17%8%1
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
28%11%38%13%7%1
135
16th to endDay
22%18%40%15%2
144
February1st to 15thDay
25%15%38%14%5%
135
16th to endDay
35%10%30%17%5%
120
March1st to 15thDay
25%17%38%16%2
216
16th to endDay
23%11%32%21%9%1
352
April1st to 15thDay
17%15%24%26%13%2
330
16th to endDay
20%7%24%26%14%7%
319
May1st to 15thDay
20%8%25%19%17%7%
348
16th to endDay
16%219%24%20%17%
395
June1st to 15thDay
10%113%23%33%16%
375
16th to endDay
8%322%25%24%15%
460
July1st to 15thDay
15%114%22%22%22%
407
16th to endDay
12%19%22%27%26%
390
August1st to 15thDay
13%18%21%29%26%
358
16th to endDay
11%12%26%28%21%
396
September1st to 15thDay
16%110%17%28%24%
375
16th to endDay
20%210%18%30%17%
374
October1st to 15thDay
12%5%18%24%26%12%
345
16th to endDay
17%6%25%29%17%4
269
November1st to 15thDay
18%5%27%24%17%5%
135
16th to endDay
23%8%26%31%8%2
135
December1st to 15thDay
19%14%34%23%5%1
135
16th to endDay
27%20%40%9%2
144
January1st to 15thNight
24%14%32%21%6%
780
16th to endNight
24%13%32%26%2
832
February1st to 15thNight
27%10%34%26%1
764
16th to endNight
23%13%39%20%2
683
March1st to 15thNight
22%13%30%27%6%
780
16th to endNight
19%10%30%27%11%
832
April1st to 15thNight
17%10%33%29%9%
636
16th to endNight
15%5%32%30%14%1
579
May1st to 15thNight
19%425%30%18%1
585
16th to endNight
10%215%35%30%5%
611
June1st to 15thNight
6%114%42%31%4
585
16th to endNight
6%113%38%34%5%
585
July1st to 15thNight
9%112%34%35%6%
555
16th to endNight
7%27%32%41%8%
612
August1st to 15thNight
7%8%31%45%7%
575
16th to endNight
5%9%32%44%6%
621
September1st to 15thNight
14%110%26%39%7%
728
16th to endNight
12%214%28%36%5%
777
October1st to 15thNight
11%418%30%29%5%
752
16th to endNight
18%5%28%29%16%2
768
November1st to 15thNight
16%7%25%28%18%3
760
16th to endNight
21%10%27%29%10%1
780
December1st to 15thNight
25%10%26%27%8%
780
16th to endNight
26%12%31%25%4
832
Page generated at 2018-10-09 10:39:16. Version ac04

Copyright 2018 A. Danko


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