Starburst Meadows Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Starburst Meadows Observatory clear sky chart from 2005-11-05 to 2018-11-30.

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
28%
16365
17%
51870
8%
16333
39%
16333
18%
34490

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
16%
780
19%
2716
6%
776
32%
776
15%
1724
January16th to endNight
13%
832
17%
2912
3%
832
30%
832
13%
1913
February1st to 15thNight
14%
764
16%
2437
5%
761
28%
761
12%
1695
February16th to endNight
19%
683
19%
2049
7%
683
35%
683
16%
1403
March1st to 15thNight
16%
780
15%
2300
5%
780
28%
780
14%
1653
March16th to endNight
22%
832
21%
2252
7%
832
34%
832
20%
1489
April1st to 15thNight
21%
772
18%
1940
5%
772
29%
772
20%
1390
April16th to endNight
26%
578
16%
1734
5%
578
35%
578
18%
1191
May1st to 15thNight
29%
585
14%
1755
8%
585
36%
585
16%
1228
May16th to endNight
28%
463
11%
1681
9%
462
35%
462
12%
1213
June1st to 15thNight
34%
390
10%
1560
9%
390
41%
390
12%
1100
June16th to endNight
41%
390
9%
1560
12%
390
46%
390
16%
1006
July1st to 15thNight
50%
370
11%
1480
17%
370
53%
370
18%
920
July16th to endNight
47%
408
13%
1546
15%
386
54%
386
18%
980
August1st to 15thNight
50%
555
13%
1696
10%
553
52%
553
21%
1128
August16th to endNight
54%
690
21%
1932
12%
690
58%
690
31%
1207
September1st to 15thNight
45%
780
18%
2048
9%
780
50%
780
30%
1354
September16th to endNight
46%
777
24%
2145
14%
777
54%
777
31%
1310
October1st to 15thNight
36%
780
21%
2205
11%
780
45%
780
24%
1446
October16th to endNight
24%
832
17%
2688
8%
832
35%
832
19%
1767
November1st to 15thNight
27%
820
22%
2667
11%
820
41%
820
19%
1709
November16th to endNight
22%
840
20%
2728
7%
840
36%
840
16%
1767
December1st to 15thNight
17%
825
16%
2896
3%
825
32%
825
14%
1953
December16th to endNight
14%
839
19%
2943
4%
839
32%
839
13%
1944

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
18%6%24424447%39%
52427
Night
18%7%2442445%6%39%
52040
Cloud CoverDay
18%6%24424446%39%
52437
Night
18%7%24424446%39%
52045
TransparencyDay
44%5%11%22%14%1
52115
Night
45%5%10%22%14%1
51870
SeeingDay
20%15%29%21%9%2
7397
Night
19%21%25%23%9%1
16365

By Month

Percentage Cloud Cover NE (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
17%5%35%435%446%40%
1552
16th to endDay
16%8%25%424446%40%
1664
February1st to 15thDay
18%8%25%5%3445%5%34%
1754
16th to endDay
15%10%35%6%2445%6%35%
1710
March1st to 15thDay
20%9%36%424336%34%
1979
16th to endDay
15%7%36%5%23335%42%
2320
April1st to 15thDay
18%6%25%5%245%5%6%37%
2337
16th to endDay
21%5%14424346%39%
2501
May1st to 15thDay
24%6%35%5%24446%33%
2527
16th to endDay
21%5%35%425%35%7%35%
2796
June1st to 15thDay
26%6%25%424347%33%
2730
16th to endDay
19%6%25%5%35%5%48%34%
2730
July1st to 15thDay
12%5%245%36%5%6%9%37%
2730
16th to endDay
15%5%235%35%6%6%9%36%
2878
August1st to 15thDay
13%5%25%425%5%6%9%38%
2492
16th to endDay
12%3144245%6%8%46%
2620
September1st to 15thDay
14%424423447%47%
2240
16th to endDay
14%5%23413336%51%
2145
October1st to 15thDay
20%6%35%423335%42%
2083
16th to endDay
19%6%25%423336%43%
1888
November1st to 15thDay
22%5%2331335%6%42%
1851
16th to endDay
23%6%24322335%42%
1881
December1st to 15thDay
22%8%3442433438%
1391
16th to endDay
22%10%35%323345%34%
1628
January1st to 15thNight
15%8%25%32345%6%41%
2716
16th to endNight
16%9%35%5%23445%38%
2912
February1st to 15thNight
15%8%36%6%36%445%34%
2436
16th to endNight
16%10%345%3434439%
2049
March1st to 15thNight
19%9%36%424346%32%
2287
16th to endNight
17%6%34423345%44%
2252
April1st to 15thNight
21%7%245%25%446%36%
1940
16th to endNight
23%5%245%24436%36%
1734
May1st to 15thNight
19%8%244346%6%8%31%
1755
16th to endNight
21%8%46%5%235%5%6%28%
1679
June1st to 15thNight
24%7%35%5%2445%6%30%
1560
16th to endNight
20%6%2433445%7%36%
1560
July1st to 15thNight
14%5%245%45%5%6%8%37%
1560
16th to endNight
15%5%245%35%5%6%9%35%
1642
August1st to 15thNight
14%5%25%4345%7%7%38%
1706
16th to endNight
13%31342445%8%46%
1932
September1st to 15thNight
14%6%24333345%47%
2048
16th to endNight
13%413323346%51%
2145
October1st to 15thNight
19%5%2442445%6%42%
2205
16th to endNight
22%5%25%424445%40%
2688
November1st to 15thNight
19%5%23424446%42%
2667
16th to endNight
18%5%24434346%42%
2728
December1st to 15thNight
21%9%24423345%37%
2896
16th to endNight
21%8%3442335%5%38%
2943

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
16%7%345%24446%40%
1552
16th to endDay
17%8%2432345%7%40%
1664
February1st to 15thDay
17%9%245%25%447%34%
1754
16th to endDay
15%10%35%5%345%5%5%36%
1710
March1st to 15thDay
21%8%35%424346%35%
1989
16th to endDay
15%7%25%5%24335%43%
2320
April1st to 15thDay
18%6%25%42345%7%38%
2337
16th to endDay
20%5%14434446%40%
2501
May1st to 15thDay
23%6%25%5%23446%33%
2527
16th to endDay
21%5%25%5%3345%7%35%
2796
June1st to 15thDay
26%5%24334346%34%
2730
16th to endDay
20%435%5%3445%6%36%
2730
July1st to 15thDay
12%5%25%5%35%5%6%9%37%
2730
16th to endDay
13%5%245%26%5%7%9%37%
2878
August1st to 15thDay
13%5%24435%5%6%9%40%
2492
16th to endDay
11%3134345%5%8%48%
2620
September1st to 15thDay
13%41442445%7%48%
2240
16th to endDay
14%5%14423335%51%
2145
October1st to 15thDay
19%6%25%423335%43%
2083
16th to endDay
19%5%34423335%43%
1888
November1st to 15thDay
21%6%24313445%43%
1851
16th to endDay
22%6%24312335%43%
1881
December1st to 15thDay
22%6%25%43434438%
1391
16th to endDay
22%10%24323346%34%
1628
January1st to 15thNight
15%7%35%42345%7%40%
2716
16th to endNight
17%10%34433446%38%
2912
February1st to 15thNight
15%8%35%6%45%445%35%
2429
16th to endNight
17%9%35%434345%38%
2049
March1st to 15thNight
20%9%36%5%34345%33%
2300
16th to endNight
17%6%34423245%44%
2251
April1st to 15thNight
20%7%24425%446%36%
1940
16th to endNight
23%5%245%23446%36%
1734
May1st to 15thNight
20%8%24425%5%6%8%32%
1755
16th to endNight
23%8%36%4245%46%28%
1679
June1st to 15thNight
24%7%35%5%2445%6%30%
1560
16th to endNight
21%5%1442445%8%36%
1560
July1st to 15thNight
15%425%5%35%5%6%8%37%
1560
16th to endNight
15%6%245%35%5%6%10%34%
1642
August1st to 15thNight
14%5%35%4345%7%7%37%
1706
16th to endNight
13%41342445%7%47%
1932
September1st to 15thNight
14%5%24433436%46%
2048
16th to endNight
13%6%14323346%50%
2145
October1st to 15thNight
19%5%2432345%6%41%
2205
16th to endNight
21%5%25%333345%40%
2688
November1st to 15thNight
19%6%24324445%42%
2667
16th to endNight
18%6%245%24346%41%
2728
December1st to 15thNight
22%8%24423345%37%
2896
16th to endNight
21%9%24413346%38%
2943

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
43%6%11%23%13%1
1553
16th to endDay
43%5%12%25%13%
1664
February1st to 15thDay
49%6%12%19%11%1
1757
16th to endDay
48%411%18%13%2
1710
March1st to 15thDay
50%411%19%11%2
1989
16th to endDay
44%37%19%19%5%
2320
April1st to 15thDay
45%6%7%20%15%3
2337
16th to endDay
45%49%21%15%3
2501
May1st to 15thDay
51%5%8%17%15%1
2527
16th to endDay
48%6%12%18%12%1
2800
June1st to 15thDay
50%5%11%20%10%
2730
16th to endDay
48%6%10%21%12%1
2730
July1st to 15thDay
38%8%13%25%13%
2581
16th to endDay
41%8%15%21%11%1
2711
August1st to 15thDay
39%8%17%25%9%
2478
16th to endDay
32%6%15%26%18%1
2620
September1st to 15thDay
35%6%11%26%18%1
2240
16th to endDay
35%49%28%20%1
2145
October1st to 15thDay
45%49%25%13%2
2083
16th to endDay
43%411%24%14%1
1888
November1st to 15thDay
43%413%23%14%1
1851
16th to endDay
44%313%19%16%1
1881
December1st to 15thDay
49%412%20%12%
1391
16th to endDay
51%49%18%14%1
1628
January1st to 15thNight
43%5%12%23%13%1
2716
16th to endNight
47%49%21%14%1
2912
February1st to 15thNight
50%5%11%19%12%1
2437
16th to endNight
48%49%22%12%2
2049
March1st to 15thNight
52%47%20%11%2
2300
16th to endNight
41%49%18%20%5%
2252
April1st to 15thNight
49%37%18%17%2
1940
16th to endNight
48%5%9%19%13%3
1734
May1st to 15thNight
48%7%10%16%14%2
1755
16th to endNight
55%6%10%16%10%1
1681
June1st to 15thNight
54%6%10%17%9%1
1560
16th to endNight
45%6%13%21%12%
1560
July1st to 15thNight
40%8%14%22%12%
1480
16th to endNight
43%7%14%22%11%
1546
August1st to 15thNight
41%9%14%24%9%
1696
16th to endNight
34%6%11%28%17%
1932
September1st to 15thNight
38%6%10%27%15%1
2048
16th to endNight
35%410%30%18%1
2145
October1st to 15thNight
42%410%25%15%1
2205
16th to endNight
45%5%10%24%13%1
2688
November1st to 15thNight
43%5%11%23%14%1
2667
16th to endNight
43%5%12%21%15%1
2728
December1st to 15thNight
49%410%23%12%
2896
16th to endNight
47%411%22%13%1
2943

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%28%31%20%6%
90
16th to endDay
20%18%38%18%3
96
February1st to 15thDay
25%21%34%17%2
280
16th to endDay
22%19%35%18%3
291
March1st to 15thDay
26%22%34%13%2
330
16th to endDay
18%25%35%14%42
352
April1st to 15thDay
21%25%30%15%5%1
330
16th to endDay
22%16%31%17%8%2
319
May1st to 15thDay
28%15%31%14%8%2
348
16th to endDay
23%14%34%21%6%1
395
June1st to 15thDay
23%14%30%22%8%1
375
16th to endDay
19%13%32%25%8%1
375
July1st to 15thDay
13%7%30%29%13%5%
365
16th to endDay
15%9%26%30%13%4
390
August1st to 15thDay
15%9%22%29%18%3
358
16th to endDay
11%8%22%31%17%8%
396
September1st to 15thDay
15%8%25%29%16%5%
375
16th to endDay
17%9%29%23%10%9%
374
October1st to 15thDay
24%13%19%25%12%4
356
16th to endDay
21%19%30%21%7%
336
November1st to 15thDay
24%20%24%19%8%2
325
16th to endDay
25%22%26%16%7%1
329
December1st to 15thDay
25%13%34%19%6%
116
16th to endDay
31%25%27%15%1
96
January1st to 15thNight
15%33%31%16%3
780
16th to endNight
19%29%32%14%3
832
February1st to 15thNight
18%29%30%18%2
764
16th to endNight
20%25%30%18%4
683
March1st to 15thNight
23%26%29%17%3
780
16th to endNight
18%27%26%20%6%
832
April1st to 15thNight
19%23%31%19%5%
772
16th to endNight
20%21%25%24%6%
578
May1st to 15thNight
20%18%25%24%9%2
585
16th to endNight
25%18%20%25%9%1
463
June1st to 15thNight
22%18%17%29%11%1
390
16th to endNight
22%16%12%36%12%
390
July1st to 15thNight
16%12%14%35%18%2
370
16th to endNight
17%16%11%32%20%1
408
August1st to 15thNight
16%9%12%35%23%1
555
16th to endNight
12%9%16%35%22%4
690
September1st to 15thNight
15%9%23%30%19%2
780
16th to endNight
16%11%20%28%18%3
777
October1st to 15thNight
21%13%22%25%15%1
780
16th to endNight
22%18%30%20%7%
832
November1st to 15thNight
19%21%27%22%6%2
820
16th to endNight
18%27%28%19%6%
840
December1st to 15thNight
24%25%27%16%5%
825
16th to endNight
23%29%28%15%2
839
Page generated at 2018-12-01 11:35:32. Version ac04

Copyright 2018 A. Danko


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