Shaver Recreation Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Shaver Recreation Center clear sky chart from 2005-11-05 to 2018-01-20.

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
50%
16102
23%
48476
16%
16062
58%
16062
29%
29935

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
33%
780
24%
2522
12%
776
48%
776
26%
1520
January16th to endNight
30%
788
26%
2560
14%
788
45%
788
25%
1555
February1st to 15thNight
35%
700
27%
2140
13%
700
51%
700
30%
1260
February16th to endNight
31%
631
27%
1893
12%
631
46%
631
29%
1138
March1st to 15thNight
36%
720
25%
2020
14%
720
46%
720
31%
1242
March16th to endNight
40%
768
21%
2112
12%
768
47%
768
30%
1332
April1st to 15thNight
47%
706
25%
1964
15%
706
54%
706
35%
1167
April16th to endNight
51%
540
26%
1641
18%
540
57%
540
31%
992
May1st to 15thNight
50%
540
19%
1620
10%
540
57%
540
29%
1002
May16th to endNight
61%
561
19%
1683
15%
561
63%
561
30%
1056
June1st to 15thNight
67%
540
15%
1620
13%
540
68%
540
28%
1049
June16th to endNight
74%
540
16%
1620
14%
540
75%
540
32%
1005
July1st to 15thNight
67%
510
10%
1530
9%
510
67%
510
24%
1048
July16th to endNight
73%
564
15%
1595
12%
531
74%
531
28%
1021
August1st to 15thNight
67%
539
15%
1609
14%
536
68%
536
24%
1094
August16th to endNight
65%
598
17%
1864
17%
598
66%
598
23%
1259
September1st to 15thNight
62%
720
17%
1980
15%
720
63%
720
27%
1327
September16th to endNight
56%
717
23%
1980
17%
717
61%
717
28%
1301
October1st to 15thNight
53%
720
31%
2040
25%
720
60%
720
35%
1217
October16th to endNight
56%
768
36%
2304
28%
768
68%
768
41%
1240
November1st to 15thNight
54%
760
29%
2405
26%
760
62%
760
35%
1338
November16th to endNight
47%
780
29%
2535
22%
780
59%
780
32%
1437
December1st to 15thNight
41%
780
25%
2535
16%
780
53%
780
26%
1562
December16th to endNight
35%
832
23%
2704
15%
832
45%
832
21%
1773

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
13%4244345%5%8%43%
49042
Night
14%42442445%7%45%
48675
TransparencyDay
37%411%21%18%5%
48743
Night
38%410%20%20%6%
48478
SeeingDay
16%5%17%24%22%14%
5888
Night
16%5%20%31%22%4
16108

By Month

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
18%5%14423345%46%
1746
16th to endDay
17%41332244450%
1768
February1st to 15thDay
14%32343335%7%47%
1720
16th to endDay
16%414423345%47%
1580
March1st to 15thDay
17%413323346%48%
1938
16th to endDay
17%41442435%7%43%
2111
April1st to 15thDay
13%313325%45%7%48%
1993
16th to endDay
11%42442445%7%49%
2316
May1st to 15thDay
12%4244345%6%7%43%
2331
16th to endDay
10%4145%25%6%6%9%42%
2431
June1st to 15thDay
7%425%6%46%7%9%12%33%
2340
16th to endDay
5%2146%46%7%8%11%40%
2340
July1st to 15thDay
9%5%26%6%47%7%8%10%31%
2340
16th to endDay
6%4247%5%7%7%8%11%33%
2465
August1st to 15thDay
11%5%245%47%6%7%10%33%
2340
16th to endDay
12%5%36%6%36%6%6%10%32%
2321
September1st to 15thDay
10%425%5%36%6%6%8%39%
1980
16th to endDay
16%5%2432345%8%44%
1980
October1st to 15thDay
15%413212235%57%
1920
16th to endDay
12%41332122361%
1920
November1st to 15thDay
13%32231335%6%55%
1780
16th to endDay
16%424322245%50%
1755
December1st to 15thDay
19%6%24323345%43%
1755
16th to endDay
25%6%14422335%40%
1872
January1st to 15thNight
17%42442334449%
2522
16th to endNight
17%5%2442334447%
2560
February1st to 15thNight
14%42332434451%
2132
16th to endNight
15%424334345%48%
1893
March1st to 15thNight
15%42432445%7%46%
2020
16th to endNight
15%424423446%45%
2112
April1st to 15thNight
13%314324336%53%
1964
16th to endNight
12%425%434447%48%
1641
May1st to 15thNight
12%5%244245%6%8%42%
1619
16th to endNight
10%4245%345%6%8%43%
1682
June1st to 15thNight
9%5%15%5%46%6%7%12%36%
1620
16th to endNight
7%3245%36%6%8%11%40%
1620
July1st to 15thNight
9%5%36%5%47%7%8%10%31%
1620
16th to endNight
6%425%6%36%7%9%11%34%
1703
August1st to 15thNight
12%425%5%46%7%7%10%32%
1620
16th to endNight
11%5%25%6%46%6%6%11%33%
1864
September1st to 15thNight
12%5%25%6%35%5%7%9%36%
1980
16th to endNight
16%425%5%25%45%6%41%
1980
October1st to 15thNight
14%32431334453%
2040
16th to endNight
11%31332234459%
2304
November1st to 15thNight
13%423312225%57%
2405
16th to endNight
16%313313345%52%
2535
December1st to 15thNight
18%5%24423335%45%
2535
16th to endNight
22%6%24424436%38%
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
41%37%19%23%5%
1747
16th to endDay
37%17%22%22%8%
1768
February1st to 15thDay
36%28%23%23%5%
1722
16th to endDay
38%36%24%20%6%
1580
March1st to 15thDay
37%37%22%21%7%
1938
16th to endDay
39%311%23%17%3
2112
April1st to 15thDay
34%39%23%22%5%
1993
16th to endDay
34%38%25%21%6%
2316
May1st to 15thDay
37%413%21%19%3
2331
16th to endDay
36%6%16%24%14%1
2435
June1st to 15thDay
38%7%20%23%8%1
2340
16th to endDay
32%8%17%23%14%3
2340
July1st to 15thDay
40%9%17%20%8%2
2201
16th to endDay
37%10%20%20%9%2
2310
August1st to 15thDay
42%7%15%21%11%1
2327
16th to endDay
45%5%17%19%10%1
2321
September1st to 15thDay
38%7%13%18%18%3
1980
16th to endDay
38%311%21%19%5%
1980
October1st to 15thDay
32%29%20%28%6%
1920
16th to endDay
29%1421%31%12%
1920
November1st to 15thDay
30%38%18%29%10%
1780
16th to endDay
36%15%21%26%7%
1755
December1st to 15thDay
43%27%20%18%7%
1755
16th to endDay
48%17%19%16%5%
1872
January1st to 15thNight
39%27%16%25%7%
2522
16th to endNight
40%2419%24%8%
2560
February1st to 15thNight
36%17%21%24%7%
2141
16th to endNight
37%27%23%22%6%
1893
March1st to 15thNight
36%39%19%22%8%
2020
16th to endNight
38%310%20%21%5%
2112
April1st to 15thNight
33%37%25%23%6%
1964
16th to endNight
37%38%22%20%7%
1641
May1st to 15thNight
38%413%22%18%2
1620
16th to endNight
37%6%13%28%12%2
1684
June1st to 15thNight
37%8%19%24%8%1
1620
16th to endNight
32%8%19%20%15%3
1620
July1st to 15thNight
42%9%21%17%7%1
1530
16th to endNight
34%11%23%19%8%2
1595
August1st to 15thNight
41%9%16%20%10%1
1609
16th to endNight
42%9%18%17%10%1
1864
September1st to 15thNight
40%7%15%19%13%3
1980
16th to endNight
42%311%19%16%5%
1980
October1st to 15thNight
34%38%20%26%7%
2040
16th to endNight
27%25%20%30%13%
2304
November1st to 15thNight
32%25%18%30%10%
2405
16th to endNight
34%35%19%27%10%
2535
December1st to 15thNight
41%27%19%20%8%
2535
16th to endNight
47%28%16%18%6%
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
24%8%30%30%5%
135
16th to endDay
17%26%32%19%4
109
February1st to 15thDay
12%16%55%14%1
90
16th to endDay
18%16%43%18%3
81
March1st to 15thDay
14%11%32%30%10%
228
16th to endDay
20%5%27%27%17%1
288
April1st to 15thDay
15%9%23%23%22%4
270
16th to endDay
15%221%27%22%10%
270
May1st to 15thDay
13%6%27%20%14%17%
288
16th to endDay
14%414%19%25%21%
331
June1st to 15thDay
10%38%26%26%24%
315
16th to endDay
9%12%24%23%30%
315
July1st to 15thDay
12%110%22%27%25%
305
16th to endDay
7%1321%35%29%
326
August1st to 15thDay
18%26%22%25%25%
313
16th to endDay
14%16%22%29%25%
332
September1st to 15thDay
16%210%18%33%18%
315
16th to endDay
20%211%23%27%15%
314
October1st to 15thDay
20%315%30%23%6%
315
16th to endDay
14%5%18%29%26%6%
336
November1st to 15thDay
22%6%17%30%19%4
198
16th to endDay
11%326%32%20%5%
135
December1st to 15thDay
26%11%29%25%7%
135
16th to endDay
30%15%35%15%21
144
January1st to 15thNight
20%10%29%32%6%
780
16th to endNight
21%9%34%31%3
788
February1st to 15thNight
16%9%32%36%4
704
16th to endNight
16%9%38%30%5%
631
March1st to 15thNight
17%9%31%32%9%
720
16th to endNight
16%7%27%33%15%
768
April1st to 15thNight
15%7%26%33%16%
706
16th to endNight
14%322%34%22%1
540
May1st to 15thNight
14%220%36%22%2
540
16th to endNight
12%211%31%36%6%
563
June1st to 15thNight
10%18%27%39%11%
540
16th to endNight
8%16%29%39%14%
540
July1st to 15thNight
12%15%27%41%11%
510
16th to endNight
9%15%22%46%15%
564
August1st to 15thNight
14%15%25%41%12%
539
16th to endNight
13%1426%42%11%
598
September1st to 15thNight
13%18%25%39%10%
720
16th to endNight
18%212%31%30%4
717
October1st to 15thNight
15%5%19%25%27%5%
720
16th to endNight
12%421%33%25%3
768
November1st to 15thNight
15%418%36%20%4
760
16th to endNight
18%5%23%32%17%1
780
December1st to 15thNight
22%5%23%34%13%1
780
16th to endNight
25%5%27%33%8%
832
Page generated at 2018-01-21 12:19:24. Version ac04

Copyright 2018 A. Danko


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