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 2017-09-19.

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
28%
14823
17%
47040
8%
14791
38%
14791
18%
31279

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
17%
720
19%
2506
6%
716
33%
716
15%
1593
January16th to endNight
11%
768
18%
2688
4%
768
30%
768
13%
1752
February1st to 15thNight
14%
704
15%
2246
5%
701
27%
701
12%
1564
February16th to endNight
19%
631
19%
1893
7%
631
36%
631
16%
1290
March1st to 15thNight
16%
720
16%
2123
5%
720
29%
720
14%
1508
March16th to endNight
22%
768
21%
2079
7%
768
33%
768
19%
1376
April1st to 15thNight
21%
712
18%
1790
4%
712
29%
712
20%
1276
April16th to endNight
27%
540
16%
1620
5%
540
36%
540
18%
1107
May1st to 15thNight
28%
540
13%
1620
7%
540
35%
540
16%
1137
May16th to endNight
27%
426
11%
1548
9%
425
34%
425
11%
1126
June1st to 15thNight
33%
360
9%
1440
9%
360
40%
360
12%
1030
June16th to endNight
41%
360
9%
1440
11%
360
45%
360
15%
934
July1st to 15thNight
47%
340
10%
1360
15%
340
51%
340
17%
866
July16th to endNight
47%
376
12%
1418
14%
354
55%
354
18%
895
August1st to 15thNight
51%
521
13%
1592
9%
519
53%
519
22%
1048
August16th to endNight
52%
637
21%
1783
13%
637
56%
637
30%
1119
September1st to 15thNight
44%
720
18%
1890
9%
720
49%
720
31%
1232
September16th to endNight
45%
673
25%
1858
14%
673
54%
673
33%
1104
October1st to 15thNight
34%
660
21%
1865
11%
660
43%
660
23%
1234
October16th to endNight
24%
704
17%
2274
7%
704
36%
704
19%
1501
November1st to 15thNight
28%
700
21%
2277
12%
700
41%
700
20%
1451
November16th to endNight
22%
720
20%
2340
7%
720
36%
720
16%
1521
December1st to 15thNight
16%
750
16%
2673
4%
750
31%
750
13%
1793
December16th to endNight
15%
773
17%
2717
4%
773
30%
773
12%
1822

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%
47771
Night
18%7%2442445%6%39%
47210
Cloud CoverDay
18%6%2442445%6%39%
47781
Night
18%7%24424446%39%
47215
TransparencyDay
44%5%11%22%14%1
47459
Night
45%5%11%22%13%1
47040
SeeingDay
20%16%28%21%9%3
5907
Night
19%22%24%22%9%1
14823

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%
1432
16th to endDay
16%8%24424446%40%
1536
February1st to 15thDay
17%8%25%5%3445%5%34%
1615
16th to endDay
14%10%35%6%25%45%6%35%
1580
March1st to 15thDay
20%9%36%324336%36%
1826
16th to endDay
16%7%36%423335%42%
2142
April1st to 15thDay
19%6%244245%5%6%38%
2157
16th to endDay
20%5%23424346%40%
2340
May1st to 15thDay
26%6%35%5%24446%31%
2332
16th to endDay
22%5%35%5%25%35%8%34%
2576
June1st to 15thDay
26%6%25%42335%7%32%
2520
16th to endDay
20%6%245%35%5%48%34%
2520
July1st to 15thDay
13%5%245%36%5%6%9%35%
2520
16th to endDay
14%4235%35%6%7%9%36%
2654
August1st to 15thDay
13%5%25%425%5%6%9%38%
2344
16th to endDay
12%3144245%6%8%46%
2417
September1st to 15thDay
14%414423447%47%
2068
16th to endDay
14%5%22413336%53%
1848
October1st to 15thDay
19%6%35%5%23335%41%
1763
16th to endDay
19%6%25%424435%41%
1598
November1st to 15thDay
21%5%3332335%6%42%
1581
16th to endDay
22%6%24322335%44%
1615
December1st to 15thDay
22%8%3442433438%
1284
16th to endDay
23%10%45%323345%34%
1503
January1st to 15thNight
15%8%35%33345%6%40%
2506
16th to endNight
16%9%35%5%23445%38%
2688
February1st to 15thNight
14%8%36%6%36%45%5%34%
2245
16th to endNight
15%10%345%3434439%
1893
March1st to 15thNight
19%9%36%424346%34%
2110
16th to endNight
17%5%345%23345%43%
2079
April1st to 15thNight
21%7%245%25%446%36%
1790
16th to endNight
22%5%245%24436%37%
1620
May1st to 15thNight
20%8%25%3346%5%7%31%
1620
16th to endNight
22%8%46%4246%5%6%27%
1546
June1st to 15thNight
25%7%35%5%2445%6%29%
1440
16th to endNight
20%6%2443445%7%36%
1440
July1st to 15thNight
15%5%245%45%5%6%8%35%
1440
16th to endNight
15%5%245%35%5%6%9%35%
1514
August1st to 15thNight
14%5%25%4345%7%7%38%
1602
16th to endNight
14%31442445%7%46%
1783
September1st to 15thNight
14%6%14333345%48%
1890
16th to endNight
13%413322336%54%
1858
October1st to 15thNight
19%5%24424446%42%
1865
16th to endNight
22%5%25%424445%39%
2274
November1st to 15thNight
18%6%23324446%42%
2277
16th to endNight
18%5%24424346%42%
2340
December1st to 15thNight
22%9%24323345%37%
2673
16th to endNight
22%8%3432335%5%37%
2717

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%6%3443445%7%40%
1432
16th to endDay
16%8%2332345%7%40%
1536
February1st to 15thDay
16%9%246%25%447%34%
1615
16th to endDay
14%10%35%5%345%5%5%36%
1580
March1st to 15thDay
20%8%35%424346%36%
1836
16th to endDay
15%7%35%5%23345%43%
2142
April1st to 15thDay
19%5%2442345%7%39%
2157
16th to endDay
19%5%14434446%41%
2340
May1st to 15thDay
25%6%25%5%24446%32%
2332
16th to endDay
22%5%25%5%3445%7%34%
2576
June1st to 15thDay
27%5%24333346%33%
2520
16th to endDay
20%435%5%3445%6%36%
2520
July1st to 15thDay
12%6%25%5%35%5%6%9%36%
2520
16th to endDay
12%5%245%26%5%7%9%37%
2654
August1st to 15thDay
13%5%24425%5%6%9%40%
2344
16th to endDay
12%3134345%5%8%47%
2417
September1st to 15thDay
14%414413447%49%
2068
16th to endDay
14%5%13323335%52%
1848
October1st to 15thDay
18%6%26%423345%42%
1763
16th to endDay
19%5%24423345%42%
1598
November1st to 15thDay
20%6%23313446%43%
1581
16th to endDay
22%5%34212335%44%
1615
December1st to 15thDay
23%6%25%32434438%
1284
16th to endDay
23%10%24423346%34%
1503
January1st to 15thNight
15%8%3442345%7%39%
2506
16th to endNight
17%9%34433446%38%
2688
February1st to 15thNight
14%8%35%7%45%5%45%34%
2238
16th to endNight
16%9%35%434345%39%
1893
March1st to 15thNight
20%9%36%434345%35%
2123
16th to endNight
17%6%24423346%43%
2078
April1st to 15thNight
20%7%24425%445%37%
1790
16th to endNight
22%5%245%23446%36%
1620
May1st to 15thNight
21%8%24325%5%6%7%32%
1620
16th to endNight
24%8%36%4245%46%28%
1546
June1st to 15thNight
25%7%35%5%2445%6%29%
1440
16th to endNight
21%5%1442445%8%35%
1440
July1st to 15thNight
16%425%5%36%5%6%7%36%
1440
16th to endNight
14%5%245%35%5%6%10%34%
1514
August1st to 15thNight
13%5%35%4345%7%7%38%
1602
16th to endNight
14%41342445%7%46%
1783
September1st to 15thNight
15%5%24423436%48%
1890
16th to endNight
12%5%13313336%53%
1858
October1st to 15thNight
19%5%2432345%6%41%
1865
16th to endNight
21%5%25%333345%39%
2274
November1st to 15thNight
18%6%24324445%43%
2277
16th to endNight
18%6%245%24345%41%
2340
December1st to 15thNight
22%8%24413345%37%
2673
16th to endNight
22%9%34413346%37%
2717

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
1433
16th to endDay
42%5%12%25%13%
1536
February1st to 15thDay
48%6%12%20%11%
1618
16th to endDay
47%5%11%19%13%2
1580
March1st to 15thDay
49%411%19%12%2
1836
16th to endDay
44%38%20%19%4
2142
April1st to 15thDay
44%6%7%20%16%3
2157
16th to endDay
44%5%9%22%14%3
2340
May1st to 15thDay
52%5%8%16%15%2
2332
16th to endDay
48%6%12%18%12%1
2580
June1st to 15thDay
51%5%12%20%9%1
2520
16th to endDay
48%6%10%21%11%1
2520
July1st to 15thDay
39%8%14%24%11%
2371
16th to endDay
40%8%15%22%11%1
2487
August1st to 15thDay
38%8%17%25%9%
2330
16th to endDay
32%7%15%25%17%1
2417
September1st to 15thDay
35%6%11%26%19%1
2068
16th to endDay
34%49%28%21%1
1848
October1st to 15thDay
45%49%24%14%2
1763
16th to endDay
44%412%24%13%1
1598
November1st to 15thDay
42%413%23%14%1
1581
16th to endDay
44%313%20%16%1
1615
December1st to 15thDay
49%412%20%12%
1284
16th to endDay
52%410%18%12%1
1503
January1st to 15thNight
43%5%12%24%12%1
2506
16th to endNight
47%49%22%14%1
2688
February1st to 15thNight
50%5%11%19%11%1
2246
16th to endNight
47%49%22%12%2
1893
March1st to 15thNight
51%48%20%12%2
2123
16th to endNight
41%5%9%18%19%5%
2079
April1st to 15thNight
48%37%19%17%2
1790
16th to endNight
47%5%10%19%13%3
1620
May1st to 15thNight
48%7%11%16%14%2
1620
16th to endNight
55%6%10%16%10%1
1548
June1st to 15thNight
55%6%10%17%8%1
1440
16th to endNight
46%6%14%20%11%
1440
July1st to 15thNight
42%8%15%22%11%
1360
16th to endNight
42%7%15%23%10%
1418
August1st to 15thNight
39%9%14%24%10%1
1592
16th to endNight
35%6%11%28%17%
1783
September1st to 15thNight
37%5%10%28%15%1
1890
16th to endNight
32%410%30%20%1
1858
October1st to 15thNight
43%49%24%15%2
1865
16th to endNight
45%5%10%24%13%1
2274
November1st to 15thNight
42%5%12%23%15%1
2277
16th to endNight
44%5%12%21%14%1
2340
December1st to 15thNight
49%410%24%11%
2673
16th to endNight
49%5%11%21%11%
2717

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
11%26%30%25%6%
60
16th to endDay
18%23%31%23%3
64
February1st to 15thDay
22%22%34%18%2
231
16th to endDay
20%21%33%20%3
239
March1st to 15thDay
24%27%30%13%3
270
16th to endDay
19%26%33%13%42
288
April1st to 15thDay
22%22%29%17%6%1
270
16th to endDay
20%20%32%14%8%3
270
May1st to 15thDay
30%16%29%12%8%2
288
16th to endDay
23%16%32%20%6%1
331
June1st to 15thDay
24%14%28%22%8%1
315
16th to endDay
21%13%31%24%7%1
315
July1st to 15thDay
15%8%30%27%13%5%
305
16th to endDay
13%11%26%30%14%3
326
August1st to 15thDay
15%10%22%29%18%4
313
16th to endDay
12%9%21%28%18%9%
332
September1st to 15thDay
15%8%26%25%16%6%
315
16th to endDay
18%9%26%22%10%11%
266
October1st to 15thDay
20%16%19%23%13%5%
246
16th to endDay
22%16%32%21%7%
240
November1st to 15thDay
22%21%23%19%10%2
235
16th to endDay
22%25%25%16%7%1
240
December1st to 15thDay
25%17%30%19%7%
84
16th to endDay
34%20%29%14%1
64
January1st to 15thNight
15%33%30%17%3
720
16th to endNight
18%31%31%14%3
768
February1st to 15thNight
17%30%30%18%2
704
16th to endNight
19%27%29%18%4
631
March1st to 15thNight
22%27%28%17%3
720
16th to endNight
17%28%26%19%6%
768
April1st to 15thNight
19%24%31%18%5%
712
16th to endNight
19%23%24%24%6%
540
May1st to 15thNight
21%20%23%23%9%1
540
16th to endNight
26%19%19%24%8%1
426
June1st to 15thNight
22%19%16%28%11%1
360
16th to endNight
21%17%13%34%12%
360
July1st to 15thNight
17%13%13%35%17%2
340
16th to endNight
16%16%12%33%19%
376
August1st to 15thNight
14%10%13%36%22%1
521
16th to endNight
13%9%16%35%21%4
637
September1st to 15thNight
15%10%23%29%18%2
720
16th to endNight
15%13%20%27%19%3
673
October1st to 15thNight
21%15%21%24%14%2
660
16th to endNight
22%18%30%21%6%
704
November1st to 15thNight
17%21%28%23%7%2
700
16th to endNight
17%28%26%19%7%
720
December1st to 15thNight
24%27%27%16%4
750
16th to endNight
24%29%28%15%2
773
Page generated at 2017-09-20 04:49:52. Version ac04

Copyright 2017 A. Danko


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