Grandview Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Grandview Campground clear sky chart from 2005-11-05 to 2017-08-12.

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
69%
15242
34%
46468
28%
15211
77%
15211
60%
20399

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
64%
716
29%
2506
24%
716
74%
716
57%
1018
January16th to endNight
58%
768
31%
2544
26%
768
69%
768
48%
1171
February1st to 15thNight
64%
700
34%
2105
28%
697
74%
697
57%
959
February16th to endNight
57%
632
32%
1895
27%
632
67%
632
53%
891
March1st to 15thNight
62%
720
30%
2160
25%
720
73%
720
58%
978
March16th to endNight
59%
768
33%
2007
19%
768
70%
768
59%
979
April1st to 15thNight
57%
719
31%
1799
15%
719
65%
719
56%
930
April16th to endNight
59%
720
34%
1800
15%
720
66%
720
62%
894
May1st to 15thNight
60%
551
32%
1631
22%
551
65%
551
58%
736
May16th to endNight
60%
502
28%
1625
22%
501
67%
501
49%
732
June1st to 15thNight
71%
360
33%
1440
34%
360
81%
360
55%
533
June16th to endNight
86%
360
38%
1440
47%
360
92%
360
75%
441
July1st to 15thNight
89%
340
31%
1360
39%
340
90%
340
53%
524
July16th to endNight
84%
397
35%
1436
41%
374
84%
374
52%
576
August1st to 15thNight
80%
701
36%
1750
24%
697
81%
697
73%
822
August16th to endNight
86%
700
41%
1750
27%
700
86%
700
77%
811
September1st to 15thNight
86%
660
44%
1664
30%
660
90%
660
77%
755
September16th to endNight
81%
656
43%
1815
37%
656
86%
656
74%
784
October1st to 15thNight
74%
660
38%
1864
34%
660
80%
660
64%
853
October16th to endNight
74%
704
42%
2177
39%
704
83%
704
68%
882
November1st to 15thNight
74%
700
38%
2275
35%
700
84%
700
71%
868
November16th to endNight
72%
720
38%
2340
33%
720
82%
720
64%
947
December1st to 15thNight
66%
720
30%
2397
22%
720
77%
720
52%
1072
December16th to endNight
56%
768
31%
2688
24%
768
70%
768
43%
1243

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
2212313346%68%
47510
Night
1212212346%70%
46650
TransparencyDay
14%38%20%28%25%
47184
Night
13%310%23%29%19%
46476
SeeingDay
5%13%33%29%13%4
5603
Night
2220%41%28%3
15252

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
121212336%9%66%
1432
16th to endDay
142431445%7%61%
1677
February1st to 15thDay
2143233410%64%
1751
16th to endDay
1314323349%62%
1579
March1st to 15thDay
21332346%8%64%
1800
16th to endDay
21231446%9%63%
2216
April1st to 15thDay
2222313347%64%
2149
16th to endDay
1212213348%69%
2160
May1st to 15thDay
2213313345%66%
2317
16th to endDay
4414423445%60%
2486
June1st to 15thDay
321331335%5%65%
2520
16th to endDay
21221123378%
2520
July1st to 15thDay
321333444464%
2520
16th to endDay
421332444463%
2632
August1st to 15thDay
212213235%74%
2114
16th to endDay
111231223475%
2100
September1st to 15thDay
22221233474%
1965
16th to endDay
1121122480%
1815
October1st to 15thDay
121221234473%
1763
16th to endDay
111212345%73%
1694
November1st to 15thDay
1211212236%74%
1584
16th to endDay
11213336%73%
1620
December1st to 15thDay
313313448%65%
1560
16th to endDay
31332336%9%62%
1536
January1st to 15thNight
121221245%7%67%
2506
16th to endNight
142332335%7%62%
2544
February1st to 15thNight
2232245%10%62%
2101
16th to endNight
1322212349%64%
1895
March1st to 15thNight
21332345%6%66%
2160
16th to endNight
121231335%9%65%
2007
April1st to 15thNight
132332335%6%66%
1799
16th to endNight
12213347%72%
1800
May1st to 15thNight
213312346%69%
1631
16th to endNight
2413222345%66%
1624
June1st to 15thNight
1112313335%72%
1440
16th to endNight
1111113383%
1440
July1st to 15thNight
12232335%6%68%
1440
16th to endNight
221321334469%
1533
August1st to 15thNight
11221123279%
1760
16th to endNight
111112335%77%
1750
September1st to 15thNight
11111232480%
1664
16th to endNight
11111123380%
1815
October1st to 15thNight
2112212335%72%
1864
16th to endNight
1212223477%
2177
November1st to 15thNight
11112227%76%
2275
16th to endNight
11221225%7%72%
2340
December1st to 15thNight
121331335%8%64%
2397
16th to endNight
121332345%8%61%
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
12%314%32%31%5%
1432
16th to endDay
20%314%25%24%10%
1677
February1st to 15thDay
15%214%28%27%10%
1751
16th to endDay
18%410%30%28%6%
1579
March1st to 15thDay
15%310%30%30%10%
1800
16th to endDay
14%315%29%27%9%
2216
April1st to 15thDay
18%210%27%28%13%
2149
16th to endDay
12%210%26%33%14%
2160
May1st to 15thDay
17%26%21%38%14%
2317
16th to endDay
21%36%19%31%16%
2489
June1st to 15thDay
17%26%13%28%32%
2520
16th to endDay
10%126%22%56%
2520
July1st to 15thDay
19%348%13%50%
2371
16th to endDay
19%36%10%16%43%
2466
August1st to 15thDay
10%35%8%18%54%
2100
16th to endDay
11%237%24%51%
2100
September1st to 15thDay
12%2211%20%49%
1965
16th to endDay
8%1212%38%35%
1815
October1st to 15thDay
12%2418%39%22%
1763
16th to endDay
11%15%20%40%21%
1694
November1st to 15thDay
10%29%31%32%12%
1584
16th to endDay
9%111%29%35%11%
1620
December1st to 15thDay
15%415%30%29%5%
1560
16th to endDay
16%7%17%27%22%8%
1536
January1st to 15thNight
13%316%30%29%6%
2506
16th to endNight
19%314%25%24%11%
2544
February1st to 15thNight
13%414%32%24%11%
2112
16th to endNight
16%314%30%29%5%
1895
March1st to 15thNight
14%311%31%26%11%
2160
16th to endNight
13%314%32%28%6%
2007
April1st to 15thNight
16%312%29%28%9%
1799
16th to endNight
12%310%30%32%11%
1800
May1st to 15thNight
14%27%26%36%11%
1632
16th to endNight
18%29%20%33%15%
1625
June1st to 15thNight
13%26%20%29%28%
1440
16th to endNight
6%138%29%50%
1440
July1st to 15thNight
15%25%11%16%47%
1360
16th to endNight
16%26%10%21%42%
1436
August1st to 15thNight
9%2410%23%49%
1750
16th to endNight
8%1312%28%44%
1750
September1st to 15thNight
8%1312%27%45%
1664
16th to endNight
8%1315%33%36%
1815
October1st to 15thNight
14%15%19%42%15%
1864
16th to endNight
9%25%22%41%17%
2177
November1st to 15thNight
8%213%29%34%12%
2275
16th to endNight
11%211%26%36%11%
2340
December1st to 15thNight
16%417%31%25%5%
2397
16th to endNight
17%7%15%28%23%8%
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
311%46%26%38%
60
16th to endDay
5%10%25%34%16%8%
199
February1st to 15thDay
49%28%30%21%4
266
16th to endDay
6%12%34%34%9%2
238
March1st to 15thDay
417%35%23%11%7%
270
16th to endDay
6%20%35%26%10%1
288
April1st to 15thDay
13%21%30%23%9%2
269
16th to endDay
11%28%35%17%5%1
270
May1st to 15thDay
8%18%38%21%10%2
288
16th to endDay
11%15%26%29%12%4
330
June1st to 15thDay
7%17%32%27%13%2
315
16th to endDay
215%29%29%16%5%
315
July1st to 15thDay
5%6%32%33%15%6%
305
16th to endDay
39%33%31%15%6%
327
August1st to 15thDay
213%43%25%11%4
300
16th to endDay
2439%33%14%5%
268
September1st to 15thDay
8%9%30%32%14%5%
255
16th to endDay
311%31%35%15%2
255
October1st to 15thDay
5%11%38%29%12%1
255
16th to endDay
49%33%36%14%1
206
November1st to 15thDay
1412%18%48%14%
90
16th to endDay
4427%46%15%1
90
December1st to 15thDay
8%33%42%15%
80
16th to endDay
36%26%35%25%3
64
January1st to 15thNight
2125%40%23%6%
720
16th to endNight
2228%39%20%5%
768
February1st to 15thNight
2421%45%22%3
704
16th to endNight
36%29%40%18%1
632
March1st to 15thNight
2226%42%21%4
720
16th to endNight
26%27%42%20%1
768
April1st to 15thNight
45%26%42%19%1
719
16th to endNight
17%27%38%22%2
720
May1st to 15thNight
3426%40%22%1
552
16th to endNight
45%21%38%27%
503
June1st to 15thNight
3315%47%29%
360
16th to endNight
9%56%31%
360
July1st to 15thNight
2241%49%3
340
16th to endNight
2443%47%1
397
August1st to 15thNight
113%42%40%2
701
16th to endNight
17%42%45%2
700
September1st to 15thNight
17%41%44%5%
660
16th to endNight
1112%35%44%4
656
October1st to 15thNight
1216%42%31%5%
660
16th to endNight
2217%38%31%7%
704
November1st to 15thNight
1120%40%29%8%
700
16th to endNight
2120%44%28%3
720
December1st to 15thNight
3324%47%18%4
720
16th to endNight
3330%40%19%2
768
Page generated at 2017-08-13 11:16:33. Version ac04

Copyright 2017 A. Danko


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