Pine Valley Creek trailhead
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pine Valley Creek trailhead clear sky chart from 2005-11-05 to 2017-09-18.

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
68%
16208
35%
46989
28%
16167
73%
16167
52%
23053

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
57%
717
29%
2327
26%
716
65%
716
39%
1202
January16th to endNight
53%
768
34%
2316
26%
768
65%
768
36%
1275
February1st to 15thNight
56%
700
32%
2111
26%
700
66%
700
40%
1135
February16th to endNight
47%
632
28%
1895
25%
632
54%
632
32%
1122
March1st to 15thNight
55%
720
31%
2144
28%
720
63%
720
42%
1125
March16th to endNight
61%
768
32%
2067
25%
768
67%
768
46%
1134
April1st to 15thNight
50%
719
32%
1799
17%
719
57%
719
48%
1004
April16th to endNight
56%
720
36%
1800
17%
720
65%
720
60%
906
May1st to 15thNight
66%
564
35%
1644
24%
564
71%
564
60%
744
May16th to endNight
67%
561
36%
1685
26%
561
72%
561
66%
708
June1st to 15thNight
76%
540
35%
1620
28%
540
79%
540
75%
639
June16th to endNight
86%
540
38%
1620
32%
540
87%
540
81%
616
July1st to 15thNight
90%
510
30%
1530
25%
510
90%
510
68%
642
July16th to endNight
85%
609
34%
1635
26%
573
86%
573
58%
777
August1st to 15thNight
92%
717
37%
1790
24%
713
92%
713
77%
825
August16th to endNight
91%
764
43%
1910
31%
764
91%
764
74%
907
September1st to 15thNight
86%
720
37%
1890
30%
720
88%
720
72%
872
September16th to endNight
83%
667
46%
1847
41%
667
87%
667
78%
762
October1st to 15thNight
68%
660
38%
1815
31%
660
74%
660
56%
883
October16th to endNight
74%
704
40%
2093
36%
704
80%
704
58%
957
November1st to 15thNight
69%
700
34%
2275
33%
700
76%
700
51%
1034
November16th to endNight
65%
720
35%
2340
34%
720
72%
720
46%
1118
December1st to 15thNight
58%
720
32%
2340
31%
720
64%
720
38%
1247
December16th to endNight
50%
768
31%
2496
25%
768
60%
768
31%
1419

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
3313313335%66%
47799
Night
3413313335%65%
47189
TransparencyDay
19%26%11%25%34%
47499
Night
18%36%11%24%35%
46991
SeeingDay
7%12%31%31%12%3
5891
Night
5%6%14%30%32%10%
16218

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
7%5%3331334458%
1611
16th to endDay
9%6%24324445%52%
1907
February1st to 15thDay
5%5%34324345%57%
1751
16th to endDay
8%9%36%424347%44%
1579
March1st to 15thDay
7%423214348%58%
1815
16th to endDay
35%24324336%59%
2154
April1st to 15thDay
5%5%35%323345%57%
2149
16th to endDay
3313212236%68%
2160
May1st to 15thDay
3314212325%69%
2304
16th to endDay
12222225%76%
2429
June1st to 15thDay
11131212478%
2340
16th to endDay
11111285%
2340
July1st to 15thDay
2212213345%70%
2340
16th to endDay
2113325%45%7%62%
2419
August1st to 15thDay
21221333475%
2160
16th to endDay
21231333471%
2292
September1st to 15thDay
2212213435%71%
2070
16th to endDay
21121122380%
1838
October1st to 15thDay
342431333368%
1815
16th to endDay
132332223372%
1774
November1st to 15thDay
444312235%66%
1584
16th to endDay
4415%212445%62%
1620
December1st to 15thDay
7%7%15%5%34347%50%
1620
16th to endDay
8%9%34413345%51%
1728
January1st to 15thNight
5%6%2432435%6%56%
2327
16th to endNight
7%7%25%423246%54%
2316
February1st to 15thNight
37%25%424445%55%
2101
16th to endNight
6%10%36%5%34345%47%
1895
March1st to 15thNight
5%425%42335%6%55%
2144
16th to endNight
36%2432445%7%54%
2067
April1st to 15thNight
36%25%413346%57%
1799
16th to endNight
2314222236%67%
1800
May1st to 15thNight
34223447%66%
1644
16th to endNight
1113212335%71%
1684
June1st to 15thNight
1211126%79%
1620
16th to endNight
1112286%
1620
July1st to 15thNight
11211233475%
1620
16th to endNight
1213223346%68%
1746
August1st to 15thNight
11111345%77%
1800
16th to endNight
1111223479%
1910
September1st to 15thNight
11221222479%
1890
16th to endNight
1111111285%
1847
October1st to 15thNight
3314213335%68%
1815
16th to endNight
121332343468%
2093
November1st to 15thNight
241431233467%
2275
16th to endNight
35%1441334463%
2340
December1st to 15thNight
7%6%34413446%53%
2340
16th to endNight
7%9%36%423235%51%
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
26%3412%26%25%
1612
16th to endDay
30%36%11%23%24%
1907
February1st to 15thDay
25%35%13%24%27%
1751
16th to endDay
35%38%13%22%16%
1579
March1st to 15thDay
22%36%13%27%26%
1815
16th to endDay
23%37%14%31%19%
2154
April1st to 15thDay
24%37%16%32%16%
2149
16th to endDay
14%35%17%31%27%
2160
May1st to 15thDay
15%26%12%29%33%
2304
16th to endDay
10%27%12%38%29%
2432
June1st to 15thDay
10%139%24%50%
2340
16th to endDay
7%12312%73%
2340
July1st to 15thDay
15%25%8%21%45%
2201
16th to endDay
19%5%8%18%25%23%
2268
August1st to 15thDay
13%25%10%27%41%
2146
16th to endDay
15%26%8%28%38%
2292
September1st to 15thDay
15%36%8%25%40%
2070
16th to endDay
11%4429%49%
1838
October1st to 15thDay
18%35%12%26%34%
1815
16th to endDay
17%247%21%46%
1774
November1st to 15thDay
19%26%12%23%35%
1584
16th to endDay
21%26%11%22%34%
1620
December1st to 15thDay
31%26%15%17%26%
1620
16th to endDay
31%47%15%23%17%
1728
January1st to 15thNight
26%35%13%22%28%
2327
16th to endNight
29%36%11%18%30%
2316
February1st to 15thNight
26%45%11%21%29%
2112
16th to endNight
35%36%10%21%21%
1895
March1st to 15thNight
24%38%11%24%26%
2144
16th to endNight
22%5%6%13%27%24%
2067
April1st to 15thNight
22%48%13%32%19%
1799
16th to endNight
14%27%14%29%30%
1800
May1st to 15thNight
13%29%11%27%36%
1645
16th to endNight
9%211%10%32%33%
1685
June1st to 15thNight
7%149%21%54%
1620
16th to endNight
6%2310%76%
1620
July1st to 15thNight
10%25%7%20%53%
1530
16th to endNight
15%46%18%28%27%
1635
August1st to 15thNight
7%2413%27%44%
1790
16th to endNight
9%248%26%48%
1910
September1st to 15thNight
10%249%28%45%
1890
16th to endNight
8%35%31%51%
1847
October1st to 15thNight
16%27%11%26%35%
1815
16th to endNight
14%36%8%20%45%
2093
November1st to 15thNight
18%249%27%36%
2275
16th to endNight
21%36%11%24%33%
2340
December1st to 15thNight
29%36%14%21%24%
2340
16th to endNight
33%37%14%19%20%
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
26%18%15%28%10%
90
16th to endDay
21%15%31%23%7%
275
February1st to 15thDay
9%15%42%24%7%
266
16th to endDay
13%26%32%20%6%
238
March1st to 15thDay
14%18%31%20%12%1
270
16th to endDay
10%19%38%21%9%2
288
April1st to 15thDay
12%24%33%18%7%2
269
16th to endDay
9%25%36%19%7%2
270
May1st to 15thDay
9%19%39%21%7%2
288
16th to endDay
417%42%24%7%3
330
June1st to 15thDay
213%36%32%11%4
315
16th to endDay
3332%36%18%5%
315
July1st to 15thDay
2125%44%19%6%
305
16th to endDay
317%49%18%10%
327
August1st to 15thDay
2126%43%14%10%
315
16th to endDay
1118%50%17%10%
332
September1st to 15thDay
3437%40%10%4
315
16th to endDay
410%31%42%7%3
264
October1st to 15thDay
6%16%37%31%8%
255
16th to endDay
7%9%32%30%19%
198
November1st to 15thDay
8%12%20%28%22%7%
90
16th to endDay
15%14%26%24%18%
90
December1st to 15thDay
5%7%17%44%22%2
90
16th to endDay
15%18%34%20%10%
96
January1st to 15thNight
8%9%17%33%22%9%
720
16th to endNight
13%7%16%33%23%5%
768
February1st to 15thNight
9%8%18%31%25%7%
704
16th to endNight
11%12%21%29%18%6%
632
March1st to 15thNight
7%11%20%33%21%5%
720
16th to endNight
7%8%19%32%25%7%
768
April1st to 15thNight
8%12%25%29%18%5%
719
16th to endNight
5%9%26%28%21%8%
720
May1st to 15thNight
37%19%39%25%5%
565
16th to endNight
27%21%36%27%5%
563
June1st to 15thNight
1217%43%29%5%
540
16th to endNight
29%40%39%8%
540
July1st to 15thNight
1229%55%10%
510
16th to endNight
2422%60%10%
609
August1st to 15thNight
223%56%16%
717
16th to endNight
2114%55%24%
764
September1st to 15thNight
25%23%51%16%
720
16th to endNight
219%29%41%15%
667
October1st to 15thNight
39%15%33%28%8%
660
16th to endNight
1413%30%31%18%
704
November1st to 15thNight
46%14%35%27%11%
700
16th to endNight
6%7%15%29%28%13%
720
December1st to 15thNight
12%5%15%31%26%8%
720
16th to endNight
13%10%18%29%22%6%
768
Page generated at 2017-09-19 04:32:27. Version ac04

Copyright 2017 A. Danko


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