Walker Pass Campground
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Walker Pass Campground clear sky chart from 2005-11-05 to

2017-09-12
.

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
60%
15592
39%
46764
27%
15552
73%
15552
61%
19936

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
58%
717
31%
2506
25%
716
71%
716
49%
1067
January16th to endNight
55%
768
38%
2435
29%
768
69%
768
46%
1147
February1st to 15thNight
54%
699
37%
2105
27%
697
68%
697
51%
980
February16th to endNight
48%
632
38%
1895
27%
632
66%
632
53%
877
March1st to 15thNight
48%
720
33%
2160
20%
720
66%
720
53%
969
March16th to endNight
46%
768
38%
2007
20%
768
61%
768
56%
977
April1st to 15thNight
40%
719
37%
1799
11%
719
56%
719
56%
872
April16th to endNight
43%
720
41%
1800
12%
720
58%
720
64%
823
May1st to 15thNight
46%
578
39%
1658
18%
578
59%
578
68%
661
May16th to endNight
46%
562
37%
1685
19%
561
60%
561
63%
652
June1st to 15thNight
58%
387
39%
1467
29%
387
75%
387
74%
455
June16th to endNight
60%
360
42%
1440
36%
360
77%
360
79%
417
July1st to 15thNight
78%
340
36%
1360
37%
340
86%
340
68%
441
July16th to endNight
83%
507
40%
1537
36%
475
84%
475
66%
620
August1st to 15thNight
78%
717
39%
1790
22%
713
81%
713
81%
788
August16th to endNight
82%
764
46%
1910
28%
764
85%
764
82%
849
September1st to 15thNight
83%
706
43%
1790
29%
706
88%
706
77%
811
September16th to endNight
76%
656
48%
1815
37%
656
86%
656
82%
716
October1st to 15thNight
64%
660
42%
1840
30%
660
78%
660
66%
822
October16th to endNight
68%
704
45%
2161
37%
704
82%
704
67%
860
November1st to 15thNight
66%
700
39%
2275
32%
700
80%
700
61%
915
November16th to endNight
67%
720
40%
2340
37%
720
76%
720
61%
951
December1st to 15thNight
60%
720
36%
2340
26%
720
74%
720
48%
1055
December16th to endNight
50%
768
33%
2649
26%
768
64%
768
43%
1211

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
211212346%73%
47886
Night
212212346%72%
46955
TransparencyDay
11%2416%28%35%
47570
Night
11%25%19%30%30%
46772
SeeingDay
5%16%31%31%12%2
5810
Night
28%24%32%25%6%
15602

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
411221335%8%65%
1432
16th to endDay
7%313322446%60%
1785
February1st to 15thDay
321322336%10%62%
1751
16th to endDay
5%11332345%7%60%
1579
March1st to 15thDay
2112125%5%7%8%62%
1800
16th to endDay
2113245%6%10%61%
2212
April1st to 15thDay
2112322348%67%
2149
16th to endDay
11112248%74%
2160
May1st to 15thDay
11112236%77%
2289
16th to endDay
211211336%74%
2429
June1st to 15thDay
11112236%79%
2490
16th to endDay
1111287%
2520
July1st to 15thDay
211111345%75%
2520
16th to endDay
222212335%72%
2519
August1st to 15thDay
11111222283%
2160
16th to endDay
111113483%
2292
September1st to 15thDay
211122481%
2089
16th to endDay
11122286%
1815
October1st to 15thDay
212212236%75%
1788
16th to endDay
222112335%75%
1711
November1st to 15thDay
212112236%74%
1584
16th to endDay
211213348%69%
1620
December1st to 15thDay
221231245%8%64%
1620
16th to endDay
421332335%8%60%
1572
January1st to 15thNight
32322335%7%64%
2506
16th to endNight
5%43212347%63%
2435
February1st to 15thNight
1223233410%62%
2101
16th to endNight
42221336%9%63%
1895
March1st to 15thNight
11123135%6%8%64%
2160
16th to endNight
11123235%5%8%64%
2007
April1st to 15thNight
1112112348%70%
1799
16th to endNight
1211236%78%
1800
May1st to 15thNight
112247%77%
1658
16th to endNight
1112236%79%
1684
June1st to 15thNight
2236%81%
1467
16th to endNight
111289%
1440
July1st to 15thNight
11111222480%
1440
16th to endNight
11121223477%
1643
August1st to 15thNight
1122385%
1800
16th to endNight
111112386%
1910
September1st to 15thNight
121122481%
1790
16th to endNight
1112386%
1815
October1st to 15thNight
211113325%75%
1840
16th to endNight
111211246%77%
2161
November1st to 15thNight
112212336%74%
2275
16th to endNight
222123410%68%
2340
December1st to 15thNight
3212323449%62%
2340
16th to endNight
321341345%9%59%
2649

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
15%310%26%29%14%
1432
16th to endDay
23%26%22%27%17%
1785
February1st to 15thDay
16%27%25%31%16%
1751
16th to endDay
20%37%25%32%11%
1579
March1st to 15thDay
14%38%26%28%19%
1800
16th to endDay
14%29%28%26%17%
2212
April1st to 15thDay
13%36%24%34%18%
2149
16th to endDay
9%15%22%39%20%
2160
May1st to 15thDay
8%1321%32%32%
2289
16th to endDay
10%1316%42%24%
2432
June1st to 15thDay
6%1212%27%50%
2490
16th to endDay
5%1314%73%
2520
July1st to 15thDay
10%216%14%64%
2371
16th to endDay
13%229%21%50%
2363
August1st to 15thDay
8%15%19%64%
2146
16th to endDay
6%1424%62%
2292
September1st to 15thDay
9%217%22%57%
2089
16th to endDay
6%16%35%50%
1815
October1st to 15thDay
11%1114%38%32%
1788
16th to endDay
12%1213%34%35%
1711
November1st to 15thDay
10%25%19%38%22%
1584
16th to endDay
12%35%22%31%23%
1620
December1st to 15thDay
16%210%27%29%13%
1620
16th to endDay
19%5%11%28%22%13%
1572
January1st to 15thNight
16%38%25%32%13%
2506
16th to endNight
20%27%21%28%19%
2435
February1st to 15thNight
17%28%24%28%19%
2112
16th to endNight
16%25%28%34%12%
1895
March1st to 15thNight
13%38%25%28%19%
2160
16th to endNight
12%39%32%28%13%
2007
April1st to 15thNight
12%16%28%35%14%
1799
16th to endNight
8%1429%40%16%
1800
May1st to 15thNight
6%1224%39%25%
1659
16th to endNight
6%1422%41%22%
1685
June1st to 15thNight
41215%32%43%
1467
16th to endNight
46%19%67%
1440
July1st to 15thNight
8%17%15%65%
1360
16th to endNight
11%128%24%51%
1537
August1st to 15thNight
6%117%20%62%
1790
16th to endNight
6%15%29%57%
1910
September1st to 15thNight
8%117%24%56%
1790
16th to endNight
48%36%48%
1815
October1st to 15thNight
10%2213%37%32%
1840
16th to endNight
8%1313%36%35%
2161
November1st to 15thNight
11%2420%36%24%
2275
16th to endNight
12%16%24%30%25%
2340
December1st to 15thNight
17%39%24%30%14%
2340
16th to endNight
18%411%26%24%13%
2649

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
13%20%40%16%6%3
60
16th to endDay
12%18%28%26%11%2
249
February1st to 15thDay
420%32%27%13%1
266
16th to endDay
10%22%36%22%7%
238
March1st to 15thDay
8%21%32%22%11%2
270
16th to endDay
8%27%34%23%6%
288
April1st to 15thDay
12%29%28%19%7%1
269
16th to endDay
5%31%40%17%41
270
May1st to 15thDay
322%38%25%6%3
288
16th to endDay
425%29%27%10%2
330
June1st to 15thDay
414%39%30%9%
315
16th to endDay
115%29%36%14%3
315
July1st to 15thDay
1428%43%16%5%
305
16th to endDay
4224%44%18%5%
327
August1st to 15thDay
36%33%39%14%3
315
16th to endDay
5%25%41%21%5%
332
September1st to 15thDay
27%27%47%13%2
300
16th to endDay
110%27%41%18%1
255
October1st to 15thDay
5%14%34%32%10%1
255
16th to endDay
413%32%32%16%1
223
November1st to 15thDay
5%10%13%25%36%8%
90
16th to endDay
313%30%36%16%
90
December1st to 15thDay
411%33%33%16%1
90
16th to endDay
222%25%31%15%1
70
January1st to 15thNight
5%6%22%30%24%10%
720
16th to endNight
7%8%22%31%22%7%
768
February1st to 15thNight
29%28%28%23%8%
704
16th to endNight
6%8%34%27%17%5%
632
March1st to 15thNight
112%32%29%17%5%
720
16th to endNight
215%33%27%16%3
768
April1st to 15thNight
319%33%24%15%3
719
16th to endNight
117%35%25%16%3
720
May1st to 15thNight
113%36%30%13%3
579
16th to endNight
218%30%31%17%
563
June1st to 15thNight
7%32%42%15%1
387
16th to endNight
1334%43%17%
360
July1st to 15thNight
214%45%34%2
340
16th to endNight
1110%48%37%1
507
August1st to 15thNight
16%45%32%4
717
16th to endNight
1112%33%41%9%
764
September1st to 15thNight
111%33%44%8%
706
16th to endNight
417%27%37%12%
656
October1st to 15thNight
15%24%33%24%9%
660
16th to endNight
17%18%27%31%13%
704
November1st to 15thNight
17%20%27%30%13%
700
16th to endNight
35%19%33%27%10%
720
December1st to 15thNight
49%20%35%23%7%
720
16th to endNight
5%9%29%26%22%6%
768
Page generated at 2017-09-13 04:39:21. Version ac04

Copyright 2017 A. Danko


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