Table Mountain Star Party at Eden Valley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Table Mountain Star Party at Eden Valley clear sky chart from 2005-11-05 to 2019-06-19.

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
48%
16963
14%
53921
12%
16936
52%
16936
22%
35655

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%
838
8%
2926
7%
836
36%
836
11%
2237
January16th to endNight
36%
896
9%
3136
8%
896
39%
896
13%
2318
February1st to 15thNight
38%
818
9%
2778
7%
817
43%
817
14%
2022
February16th to endNight
44%
736
14%
2268
10%
736
51%
736
19%
1573
March1st to 15thNight
41%
840
13%
2520
9%
840
46%
840
18%
1798
March16th to endNight
40%
896
11%
2337
5%
896
44%
896
19%
1722
April1st to 15thNight
45%
839
13%
2099
6%
839
48%
839
22%
1535
April16th to endNight
50%
616
15%
1864
12%
616
53%
616
24%
1215
May1st to 15thNight
55%
419
18%
1679
22%
419
64%
419
25%
931
May16th to endNight
59%
438
10%
1752
15%
438
62%
438
19%
1091
June1st to 15thNight
57%
420
8%
1523
7%
420
59%
420
24%
913
June16th to endNight
62%
398
10%
1318
4%
398
64%
398
32%
748
July1st to 15thNight
70%
370
13%
1480
12%
370
75%
370
43%
620
July16th to endNight
76%
408
21%
1544
32%
386
82%
386
53%
592
August1st to 15thNight
83%
384
28%
1528
40%
382
86%
382
50%
610
August16th to endNight
71%
711
30%
1953
21%
711
75%
711
54%
973
September1st to 15thNight
71%
780
28%
1950
15%
780
75%
780
53%
1056
September16th to endNight
66%
776
25%
2103
19%
776
68%
776
37%
1273
October1st to 15thNight
54%
780
19%
2335
17%
780
58%
780
29%
1441
October16th to endNight
50%
832
17%
2677
15%
832
55%
832
21%
1770
November1st to 15thNight
40%
820
11%
2763
9%
820
44%
820
14%
2015
November16th to endNight
32%
864
8%
2964
6%
864
35%
864
11%
2284
December1st to 15thNight
37%
1050
11%
3150
8%
1050
40%
1050
15%
2347
December16th to endNight
28%
1034
11%
3274
6%
1034
34%
1034
11%
2571

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
10%7%36%5%35%45%7%40%
54778
Night
11%9%36%42445%7%38%
54089
Cloud CoverDay
11%9%36%5%3445%6%37%
54778
Night
12%10%36%5%3445%6%37%
54093
TransparencyDay
44%5%12%23%11%2
54449
Night
45%5%13%22%11%2
53922
SeeingDay
17%14%26%25%13%3
7830
Night
17%7%16%33%21%4
16973

By Month

Percentage Cloud Cover NW (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%13%5%7%5%35%5%46%23%
1672
16th to endDay
15%14%6%8%6%2446%6%25%
1792
February1st to 15thDay
12%13%48%6%35%46%7%27%
1745
16th to endDay
10%11%47%7%36%5%6%7%30%
1777
March1st to 15thDay
15%12%45%6%35%6%7%7%26%
2100
16th to endDay
11%10%5%8%8%45%5%7%8%26%
2587
April1st to 15thDay
12%9%49%7%47%5%5%6%26%
2509
16th to endDay
8%8%37%7%35%5%6%9%35%
2698
May1st to 15thDay
8%6%25%5%35%5%7%8%40%
2931
16th to endDay
12%7%26%7%46%6%6%7%32%
3063
June1st to 15thDay
12%6%36%5%46%46%8%35%
3094
16th to endDay
9%5%25%5%345%7%8%41%
3020
July1st to 15thDay
231332345%7%61%
2730
16th to endDay
3212323446%66%
2881
August1st to 15thDay
2213323447%64%
2676
16th to endDay
321232445%8%60%
2597
September1st to 15thDay
2313423336%64%
2340
16th to endDay
8%424434447%50%
2187
October1st to 15thDay
10%5%25%5%2445%8%43%
1953
16th to endDay
16%9%46%5%24346%36%
1898
November1st to 15thDay
18%10%35%5%45%45%6%29%
1753
16th to endDay
17%14%5%7%5%25%47%5%24%
1641
December1st to 15thDay
13%11%5%8%5%35%45%6%28%
1470
16th to endDay
17%15%5%8%7%2445%6%23%
1664
January1st to 15thNight
21%15%6%7%5%2335%7%21%
2926
16th to endNight
14%17%5%9%5%25%45%6%22%
3136
February1st to 15thNight
14%15%5%6%42445%6%29%
2766
16th to endNight
8%10%46%5%345%6%7%34%
2268
March1st to 15thNight
13%10%36%5%345%7%8%30%
2520
16th to endNight
10%8%47%7%35%5%6%7%32%
2333
April1st to 15thNight
9%7%47%6%36%5%6%7%35%
2099
16th to endNight
5%7%35%435%6%6%8%40%
1864
May1st to 15thNight
6%5%15%435%5%6%7%48%
1679
16th to endNight
9%7%35%5%35%7%7%8%37%
1752
June1st to 15thNight
10%3245%35%5%7%10%40%
1523
16th to endNight
5%423445%5%5%7%50%
1318
July1st to 15thNight
221221235%6%68%
1560
16th to endNight
112123346%72%
1640
August1st to 15thNight
1112212347%69%
1536
16th to endNight
22232345%8%65%
1953
September1st to 15thNight
3213222347%66%
1950
16th to endNight
6%5%2432445%7%53%
2103
October1st to 15thNight
11%6%35%32345%7%46%
2335
16th to endNight
16%7%25%5%245%5%7%37%
2677
November1st to 15thNight
20%10%35%5%2446%7%28%
2763
16th to endNight
20%13%5%7%5%35%445%24%
2964
December1st to 15thNight
14%12%6%9%6%2445%5%26%
3150
16th to endNight
17%19%7%8%5%2334424%
3274

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
18%14%5%8%6%44445%23%
1672
16th to endDay
14%16%37%5%23448%27%
1792
February1st to 15thDay
13%15%5%7%6%36%35%6%26%
1745
16th to endDay
11%13%5%8%6%35%6%5%6%26%
1777
March1st to 15thDay
14%15%46%7%345%6%6%25%
2100
16th to endDay
12%12%5%8%8%45%5%6%8%21%
2587
April1st to 15thDay
13%13%5%10%8%35%5%5%5%22%
2509
16th to endDay
9%11%48%7%35%46%7%31%
2698
May1st to 15thDay
10%8%36%6%35%5%6%6%36%
2931
16th to endDay
14%8%38%7%45%5%5%7%28%
3063
June1st to 15thDay
14%7%47%6%36%5%5%7%31%
3094
16th to endDay
10%7%35%5%35%5%5%8%38%
3020
July1st to 15thDay
4414323447%58%
2730
16th to endDay
3213323445%65%
2881
August1st to 15thDay
3314423446%61%
2676
16th to endDay
4313424446%59%
2597
September1st to 15thDay
35%14413245%61%
2340
16th to endDay
10%6%25%5%2345%7%47%
2187
October1st to 15thDay
13%7%25%43445%6%41%
1953
16th to endDay
17%10%46%5%33446%34%
1898
November1st to 15thDay
18%13%46%5%3435%6%28%
1753
16th to endDay
16%15%5%7%5%2345%6%25%
1641
December1st to 15thDay
12%11%7%6%6%345%47%28%
1470
16th to endDay
17%16%5%8%6%24446%23%
1664
January1st to 15thNight
20%14%5%9%5%24346%22%
2926
16th to endNight
13%17%5%9%6%3435%6%24%
3136
February1st to 15thNight
14%15%5%6%5%34446%30%
2766
16th to endNight
9%12%5%6%5%35%5%5%7%33%
2268
March1st to 15thNight
13%13%37%5%345%5%8%29%
2520
16th to endNight
10%10%48%8%445%5%7%30%
2337
April1st to 15thNight
10%10%46%7%36%6%5%5%33%
2099
16th to endNight
6%9%46%6%35%5%5%6%38%
1864
May1st to 15thNight
7%6%25%5%25%45%6%45%
1679
16th to endNight
11%7%35%5%45%6%6%7%35%
1752
June1st to 15thNight
11%425%5%45%6%7%8%38%
1523
16th to endNight
7%5%15%435%5%5%7%46%
1318
July1st to 15thNight
231231325%6%66%
1560
16th to endNight
1111223347%70%
1640
August1st to 15thNight
22231335%8%67%
1536
16th to endNight
311232346%7%63%
1953
September1st to 15thNight
421322335%7%63%
1950
16th to endNight
9%5%1433445%7%49%
2103
October1st to 15thNight
12%7%2442445%6%44%
2335
16th to endNight
16%8%35%5%2445%7%36%
2677
November1st to 15thNight
20%11%46%5%2445%6%27%
2763
16th to endNight
19%15%5%8%6%34345%23%
2964
December1st to 15thNight
13%13%5%10%6%35%35%6%27%
3150
16th to endNight
17%19%6%8%5%2333424%
3274

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
61%412%15%5%
1672
16th to endDay
55%415%18%5%1
1792
February1st to 15thDay
56%6%16%14%5%
1745
16th to endDay
54%6%13%17%7%
1777
March1st to 15thDay
56%5%14%16%5%
2100
16th to endDay
58%6%13%17%4
2587
April1st to 15thDay
60%6%12%15%5%
2509
16th to endDay
48%7%11%21%9%1
2698
May1st to 15thDay
44%413%28%8%1
2931
16th to endDay
52%5%13%21%6%
3067
June1st to 15thDay
49%5%9%23%9%2
3094
16th to endDay
42%310%26%14%
3020
July1st to 15thDay
25%48%26%24%10%
2581
16th to endDay
21%36%27%31%10%
2714
August1st to 15thDay
23%38%32%25%6%
2659
16th to endDay
24%310%34%22%4
2597
September1st to 15thDay
23%311%33%23%4
2340
16th to endDay
35%414%29%13%2
2187
October1st to 15thDay
40%5%15%26%11%
1953
16th to endDay
49%5%14%24%6%
1898
November1st to 15thDay
55%6%14%16%6%1
1753
16th to endDay
57%5%14%17%4
1641
December1st to 15thDay
53%7%15%20%4
1470
16th to endDay
60%5%11%16%5%
1664
January1st to 15thNight
62%5%13%14%4
2926
16th to endNight
59%414%14%5%1
3136
February1st to 15thNight
54%6%16%15%5%1
2778
16th to endNight
49%5%16%22%6%
2268
March1st to 15thNight
50%6%16%20%6%
2520
16th to endNight
52%5%14%20%7%
2337
April1st to 15thNight
50%414%22%7%
2099
16th to endNight
43%5%13%27%9%1
1864
May1st to 15thNight
36%412%30%14%1
1680
16th to endNight
44%5%15%25%8%
1752
June1st to 15thNight
39%5%10%29%12%2
1523
16th to endNight
32%414%29%16%1
1318
July1st to 15thNight
19%38%31%26%10%
1480
16th to endNight
14%29%27%32%13%
1544
August1st to 15thNight
14%49%33%31%6%
1528
16th to endNight
18%311%34%28%4
1953
September1st to 15thNight
19%311%31%28%5%
1950
16th to endNight
32%5%12%31%14%4
2103
October1st to 15thNight
38%315%26%14%1
2335
16th to endNight
45%5%13%28%7%
2677
November1st to 15thNight
54%7%16%14%5%1
2763
16th to endNight
62%412%14%5%
2964
December1st to 15thNight
56%5%14%18%4
3150
16th to endNight
63%5%9%14%6%
3274

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
25%6%8%30%21%8%
120
16th to endDay
28%7%22%28%10%2
128
February1st to 15thDay
19%15%30%25%7%1
225
16th to endDay
18%14%29%23%11%1
324
March1st to 15thDay
28%18%26%14%10%1
390
16th to endDay
23%20%25%18%10%1
416
April1st to 15thDay
29%19%26%16%5%2
389
16th to endDay
17%25%25%19%8%3
378
May1st to 15thDay
18%19%28%22%9%2
408
16th to endDay
20%9%20%27%16%5%
458
June1st to 15thDay
16%11%23%28%16%3
589
16th to endDay
12%12%27%27%16%3
632
July1st to 15thDay
7%12%32%34%10%2
365
16th to endDay
411%35%28%15%5%
391
August1st to 15thDay
6%6%25%35%18%7%
359
16th to endDay
7%12%28%31%14%5%
396
September1st to 15thDay
7%16%28%25%17%5%
375
16th to endDay
14%14%28%27%13%2
375
October1st to 15thDay
20%16%26%25%9%1
375
16th to endDay
24%8%18%26%16%4
218
November1st to 15thDay
24%15%22%27%8%
151
16th to endDay
28%15%21%14%16%4
120
December1st to 15thDay
19%7%20%23%18%10%
120
16th to endDay
24%13%18%35%6%2
128
January1st to 15thNight
24%9%17%31%15%2
840
16th to endNight
20%5%18%37%15%2
896
February1st to 15thNight
22%7%18%31%16%3
824
16th to endNight
15%7%21%33%19%3
736
March1st to 15thNight
20%9%20%28%18%3
840
16th to endNight
15%11%20%32%16%2
896
April1st to 15thNight
15%9%18%33%19%4
839
16th to endNight
11%11%20%34%18%3
616
May1st to 15thNight
10%7%20%35%21%4
420
16th to endNight
14%5%11%26%33%7%
439
June1st to 15thNight
11%5%15%35%27%4
420
16th to endNight
10%5%15%36%28%4
398
July1st to 15thNight
37%14%34%34%5%
370
16th to endNight
1413%37%37%5%
408
August1st to 15thNight
228%28%46%11%
384
16th to endNight
5%316%34%33%6%
711
September1st to 15thNight
5%6%13%30%32%13%
780
16th to endNight
12%410%39%26%7%
776
October1st to 15thNight
18%6%13%30%27%2
780
16th to endNight
21%5%14%33%21%3
832
November1st to 15thNight
25%10%17%34%10%1
820
16th to endNight
29%8%16%26%16%2
864
December1st to 15thNight
22%7%15%35%16%2
1050
16th to endNight
26%7%21%35%8%
1034
Page generated at 2019-06-20 05:02:29. Version ac04

Copyright 2019 A. Danko


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