Morgan County Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Morgan County Observatory clear sky chart from 2005-11-05 to 2017-05-01.

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
32%
14832
20%
45705
10%
14794
43%
14794
20%
29102

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
18%
717
19%
2383
7%
716
33%
716
13%
1564
January16th to endNight
15%
768
18%
2496
4%
768
33%
768
14%
1635
February1st to 15thNight
18%
702
19%
2287
5%
701
34%
701
15%
1426
February16th to endNight
15%
631
20%
1943
5%
631
33%
631
13%
1281
March1st to 15thNight
18%
720
19%
1980
7%
720
31%
720
17%
1319
March16th to endNight
18%
768
20%
2112
7%
768
30%
768
17%
1422
April1st to 15thNight
19%
718
16%
1802
4%
718
26%
718
20%
1249
April16th to endNight
34%
696
19%
1776
6%
696
41%
696
22%
1183
May1st to 15thNight
31%
498
18%
1494
8%
498
39%
498
17%
1027
May16th to endNight
39%
362
18%
1389
12%
362
50%
362
18%
830
June1st to 15thNight
39%
330
20%
1320
18%
330
50%
330
20%
762
June16th to endNight
47%
330
18%
1320
16%
330
57%
330
23%
742
July1st to 15thNight
52%
335
14%
1265
14%
335
56%
335
19%
783
July16th to endNight
55%
522
15%
1469
9%
489
64%
489
32%
869
August1st to 15thNight
55%
494
20%
1474
12%
491
60%
491
28%
905
August16th to endNight
61%
652
21%
1702
13%
652
63%
652
33%
1074
September1st to 15thNight
54%
660
26%
1650
14%
660
59%
660
32%
1067
September16th to endNight
45%
657
22%
1832
15%
657
51%
657
25%
1193
October1st to 15thNight
42%
660
24%
1980
19%
660
52%
660
26%
1248
October16th to endNight
33%
704
28%
2112
13%
704
52%
704
27%
1243
November1st to 15thNight
33%
700
24%
2191
14%
700
46%
700
24%
1307
November16th to endNight
25%
720
20%
2520
9%
720
41%
720
14%
1585
December1st to 15thNight
20%
720
16%
2520
6%
720
34%
720
12%
1649
December16th to endNight
19%
768
19%
2688
6%
768
35%
768
12%
1739

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
14%5%25%5%35%5%5%7%38%
46046
Night
13%5%245%2445%7%41%
45890
Cloud CoverDay
14%5%25%5%35%5%5%7%39%
46056
Night
14%5%2442445%7%42%
45894
TransparencyDay
43%5%12%21%14%2
45749
Night
40%5%12%23%15%2
45705
SeeingDay
18%18%20%19%15%6%
5040
Night
15%25%21%23%11%1
14838

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
14%6%37%6%35%46%6%34%
1555
16th to endDay
14%8%37%5%35%45%7%35%
1728
February1st to 15thDay
13%9%46%6%35%5%45%35%
1575
16th to endDay
11%8%38%6%34345%38%
1528
March1st to 15thDay
16%7%25%5%34445%40%
1969
16th to endDay
16%8%35%5%35%45%6%36%
2112
April1st to 15thDay
13%6%36%6%34447%38%
2146
16th to endDay
18%5%25%5%24445%41%
2194
May1st to 15thDay
18%5%25%5%35%6%5%7%34%
2138
16th to endDay
15%5%25%6%4445%7%38%
2374
June1st to 15thDay
12%424425%6%8%9%38%
2310
16th to endDay
9%4246%36%6%7%8%38%
2310
July1st to 15thDay
10%5%25%6%46%5%7%8%37%
2279
16th to endDay
8%425%6%46%8%7%10%35%
2283
August1st to 15thDay
9%426%6%46%7%7%10%33%
2145
16th to endDay
12%3145%35%6%7%8%42%
2135
September1st to 15thDay
15%424424448%44%
1980
16th to endDay
15%6%25%5%35%446%39%
1795
October1st to 15thDay
20%413324446%44%
1650
16th to endDay
13%5%25%5%2445%7%43%
1760
November1st to 15thDay
12%5%23424446%49%
1664
16th to endDay
18%5%346%3345%6%39%
1440
December1st to 15thDay
17%6%26%5%35%5%6%5%34%
1440
16th to endDay
16%6%38%6%35%5%5%6%32%
1536
January1st to 15thNight
16%7%35%5%25%5%5%6%36%
2383
16th to endNight
14%8%35%5%245%5%7%36%
2496
February1st to 15thNight
13%7%2442446%8%39%
2285
16th to endNight
11%8%35%6%345%6%7%36%
1943
March1st to 15thNight
17%5%25%42445%6%41%
1968
16th to endNight
15%6%35%5%24346%41%
2112
April1st to 15thNight
14%6%25%6%245%6%5%39%
1802
16th to endNight
15%4244335%5%7%43%
1776
May1st to 15thNight
18%6%345%36%45%7%35%
1494
16th to endNight
13%4235%2446%8%44%
1387
June1st to 15thNight
11%425%32447%9%44%
1320
16th to endNight
7%3245%35%46%11%44%
1320
July1st to 15thNight
8%5%25%6%36%46%8%43%
1347
16th to endNight
6%213436%7%7%12%43%
1577
August1st to 15thNight
8%425%436%5%6%9%45%
1485
16th to endNight
11%3144235%5%8%47%
1702
September1st to 15thNight
12%42342445%7%46%
1650
16th to endNight
14%5%34434446%45%
1832
October1st to 15thNight
18%41441345%6%45%
1980
16th to endNight
14%21342345%6%50%
2112
November1st to 15thNight
13%7%34423345%48%
2191
16th to endNight
14%6%245%3445%6%40%
2520
December1st to 15thNight
16%6%36%5%35%5%5%6%35%
2520
16th to endNight
15%7%25%5%345%5%9%35%
2688

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
14%6%26%6%35%5%6%7%34%
1555
16th to endDay
14%7%36%6%35%35%7%36%
1728
February1st to 15thDay
13%10%46%6%4435%5%36%
1575
16th to endDay
11%7%38%6%34346%39%
1528
March1st to 15thDay
16%7%26%434345%41%
1980
16th to endDay
16%8%35%5%245%5%7%36%
2111
April1st to 15thDay
13%7%35%5%35%447%39%
2146
16th to endDay
18%6%145%25%445%41%
2194
May1st to 15thDay
19%5%345%35%5%5%7%34%
2138
16th to endDay
15%425%6%45%447%39%
2374
June1st to 15thDay
13%324435%6%7%10%39%
2310
16th to endDay
10%425%5%46%6%6%9%39%
2310
July1st to 15thDay
11%425%6%46%5%7%8%37%
2279
16th to endDay
8%426%6%37%6%7%10%36%
2283
August1st to 15thDay
11%5%15%6%46%7%7%9%33%
2145
16th to endDay
12%315%435%5%6%8%42%
2135
September1st to 15thDay
15%5%243245%47%44%
1980
16th to endDay
16%5%26%425%447%39%
1795
October1st to 15thDay
20%413324346%44%
1650
16th to endDay
14%5%2443345%6%44%
1760
November1st to 15thDay
12%5%23424346%49%
1664
16th to endDay
19%5%245%2435%6%39%
1440
December1st to 15thDay
17%6%35%5%25%5%6%5%35%
1440
16th to endDay
16%7%26%6%345%5%7%33%
1536
January1st to 15thNight
16%7%25%5%26%45%6%37%
2383
16th to endNight
14%8%35%4245%5%7%37%
2496
February1st to 15thNight
13%7%2442445%8%41%
2278
16th to endNight
11%8%35%5%35%5%5%7%37%
1943
March1st to 15thNight
16%5%145%245%5%6%42%
1980
16th to endNight
15%7%35%433445%42%
2112
April1st to 15thNight
15%5%345%245%6%6%39%
1802
16th to endNight
16%42433445%6%44%
1776
May1st to 15thNight
19%5%24425%45%7%36%
1493
16th to endNight
13%42442446%8%43%
1387
June1st to 15thNight
12%3244245%7%9%44%
1320
16th to endNight
8%334325%5%6%11%44%
1320
July1st to 15thNight
9%5%25%445%46%9%42%
1347
16th to endNight
5%3135%36%7%8%10%44%
1577
August1st to 15thNight
8%415%335%5%6%8%46%
1485
16th to endNight
11%3144245%6%8%48%
1702
September1st to 15thNight
12%42342445%8%47%
1650
16th to endNight
15%425%343435%45%
1832
October1st to 15thNight
18%5%2342245%6%45%
1980
16th to endNight
14%21332445%6%51%
2112
November1st to 15thNight
13%5%35%423236%49%
2191
16th to endNight
16%5%245%34447%41%
2520
December1st to 15thNight
16%6%35%6%36%45%6%36%
2520
16th to endNight
15%6%345%345%6%9%36%
2688

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
46%5%12%21%12%1
1556
16th to endDay
46%5%12%22%11%2
1728
February1st to 15thDay
49%312%21%10%2
1577
16th to endDay
46%314%23%11%1
1528
March1st to 15thDay
45%410%22%14%1
1980
16th to endDay
47%412%18%14%2
2112
April1st to 15thDay
43%411%19%17%2
2146
16th to endDay
43%48%20%18%5%
2194
May1st to 15thDay
47%6%12%19%13%1
2138
16th to endDay
44%5%13%21%11%2
2378
June1st to 15thDay
37%9%14%22%14%1
2310
16th to endDay
39%7%15%20%14%1
2310
July1st to 15thDay
43%7%12%19%14%3
2132
16th to endDay
38%8%14%19%16%2
2128
August1st to 15thDay
43%7%13%20%14%
2132
16th to endDay
37%7%12%25%14%2
2135
September1st to 15thDay
39%5%11%20%21%2
1980
16th to endDay
44%46%22%19%1
1795
October1st to 15thDay
41%410%25%15%2
1650
16th to endDay
39%5%9%26%17%1
1760
November1st to 15thDay
36%312%20%21%5%
1664
16th to endDay
45%410%23%14%1
1440
December1st to 15thDay
46%7%15%19%10%1
1440
16th to endDay
50%5%11%21%10%
1536
January1st to 15thNight
46%412%19%14%3
2383
16th to endNight
44%5%13%23%11%1
2496
February1st to 15thNight
41%413%23%13%2
2287
16th to endNight
43%5%12%23%13%1
1943
March1st to 15thNight
42%5%13%25%11%1
1980
16th to endNight
44%411%22%15%1
2112
April1st to 15thNight
43%410%21%16%2
1802
16th to endNight
39%5%11%20%16%6%
1776
May1st to 15thNight
46%6%9%22%13%1
1494
16th to endNight
37%7%14%23%15%1
1389
June1st to 15thNight
35%6%11%28%15%1
1320
16th to endNight
33%6%14%26%15%2
1320
July1st to 15thNight
38%9%12%20%13%4
1265
16th to endNight
28%9%19%21%18%2
1469
August1st to 15thNight
34%7%13%24%19%1
1474
16th to endNight
33%6%12%24%19%3
1702
September1st to 15thNight
34%6%12%20%23%2
1650
16th to endNight
41%47%23%20%2
1832
October1st to 15thNight
39%410%24%18%2
1980
16th to endNight
33%310%29%21%1
2112
November1st to 15thNight
38%28%23%19%7%
2191
16th to endNight
42%49%22%17%2
2520
December1st to 15thNight
47%412%23%11%
2520
16th to endNight
44%6%15%22%10%
2688

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
27%34%19%9%8%
81
16th to endDay
35%23%28%9%3
96
February1st to 15thDay
32%26%35%41
90
16th to endDay
23%32%23%18%1
171
March1st to 15thDay
23%30%21%20%4
270
16th to endDay
23%29%24%14%6%2
288
April1st to 15thDay
17%28%23%17%10%2
270
16th to endDay
21%20%22%15%12%7%
270
May1st to 15thDay
26%26%16%14%9%6%
229
16th to endDay
20%17%14%17%19%9%
267
June1st to 15thDay
17%18%23%16%17%6%
255
16th to endDay
12%17%21%29%12%5%
255
July1st to 15thDay
14%11%25%20%20%8%
245
16th to endDay
7%12%14%27%23%14%
270
August1st to 15thDay
15%7%17%21%26%11%
253
16th to endDay
11%7%9%23%30%18%
268
September1st to 15thDay
15%10%14%16%25%17%
255
16th to endDay
21%9%15%22%21%9%
254
October1st to 15thDay
25%9%13%26%19%6%
255
16th to endDay
13%19%30%19%15%1
272
November1st to 15thDay
16%19%21%19%18%3
242
16th to endDay
23%20%23%20%13%
60
December1st to 15thDay
21%31%18%13%13%1
60
16th to endDay
25%17%37%17%3
64
January1st to 15thNight
20%32%24%19%4
720
16th to endNight
18%33%29%18%
768
February1st to 15thNight
16%33%26%21%1
704
16th to endNight
18%36%26%16%2
631
March1st to 15thNight
20%31%26%17%4
720
16th to endNight
17%31%28%17%4
768
April1st to 15thNight
16%32%28%17%4
718
16th to endNight
17%27%18%26%10%
696
May1st to 15thNight
20%24%19%22%12%1
498
16th to endNight
14%23%15%29%15%1
363
June1st to 15thNight
10%20%24%23%20%
330
16th to endNight
7%19%18%36%16%
330
July1st to 15thNight
11%14%13%31%27%1
335
16th to endNight
5%18%14%29%27%4
522
August1st to 15thNight
10%11%15%33%24%2
494
16th to endNight
10%10%10%35%29%4
652
September1st to 15thNight
11%12%15%26%29%3
660
16th to endNight
15%13%18%23%25%2
657
October1st to 15thNight
20%14%17%26%18%2
660
16th to endNight
14%22%25%27%9%
704
November1st to 15thNight
14%24%22%25%12%1
700
16th to endNight
17%33%18%22%6%
720
December1st to 15thNight
17%32%22%21%5%
720
16th to endNight
18%33%23%22%1
768
Page generated at 2017-05-02 08:43:26. Version ac04

Copyright 2017 A. Danko


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