Ohatchee's Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ohatchee's 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
61%
15161
23%
47033
19%
15118
65%
15118
32%
27965

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
43%
720
24%
2181
13%
716
54%
716
29%
1358
January16th to endNight
37%
768
25%
2304
14%
768
47%
768
26%
1479
February1st to 15thNight
43%
702
29%
2107
16%
699
54%
699
34%
1244
February16th to endNight
38%
631
23%
1893
12%
631
47%
631
27%
1210
March1st to 15thNight
46%
720
22%
2160
13%
720
53%
720
30%
1336
March16th to endNight
57%
639
27%
2013
22%
639
62%
639
34%
1149
April1st to 15thNight
56%
539
24%
1797
23%
539
62%
539
33%
1016
April16th to endNight
66%
540
29%
1800
29%
540
71%
540
42%
901
May1st to 15thNight
69%
539
21%
1784
20%
539
72%
539
36%
973
May16th to endNight
76%
561
23%
1682
23%
561
77%
561
37%
981
June1st to 15thNight
76%
540
14%
1620
15%
540
76%
540
35%
957
June16th to endNight
77%
540
15%
1620
16%
540
77%
540
31%
995
July1st to 15thNight
83%
510
11%
1579
12%
510
83%
510
30%
975
July16th to endNight
80%
564
10%
1772
14%
531
80%
531
26%
1115
August1st to 15thNight
83%
539
10%
1788
12%
536
83%
536
28%
1104
August16th to endNight
72%
573
14%
1910
17%
573
72%
573
22%
1234
September1st to 15thNight
72%
591
18%
1851
19%
591
73%
591
28%
1153
September16th to endNight
72%
673
26%
1858
22%
673
73%
673
35%
1146
October1st to 15thNight
74%
660
34%
1815
28%
660
76%
660
47%
974
October16th to endNight
63%
704
35%
2059
30%
704
69%
704
43%
1112
November1st to 15thNight
63%
700
31%
2264
30%
700
69%
700
36%
1234
November16th to endNight
54%
720
29%
2340
25%
720
63%
720
36%
1281
December1st to 15thNight
48%
720
25%
2340
21%
720
55%
720
27%
1407
December16th to endNight
41%
768
21%
2496
16%
768
48%
768
23%
1631

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
9%5%25%5%35%5%6%8%41%
47749
Night
8%42442445%8%47%
47255
TransparencyDay
37%8%12%18%16%6%
47467
Night
32%7%14%19%18%8%
47041
SeeingDay
11%212%20%29%24%
5118
Night
11%317%29%29%9%
15166

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
10%5%25%5%2445%8%45%
1755
16th to endDay
17%6%35%31343445%
1920
February1st to 15thDay
12%5%24323447%48%
1750
16th to endDay
13%5%34425%447%44%
1580
March1st to 15thDay
12%5%25%435%448%44%
1800
16th to endDay
9%5%25%42345%6%49%
2218
April1st to 15thDay
11%423425%46%6%46%
2151
16th to endDay
7%4143245%6%9%50%
2160
May1st to 15thDay
8%423435%5%7%9%45%
2163
16th to endDay
5%425%5%35%5%7%9%44%
2431
June1st to 15thDay
7%5%345%47%8%10%11%32%
2340
16th to endDay
7%425%7%47%8%8%12%31%
2340
July1st to 15thDay
6%5%37%8%5%9%8%9%11%24%
2284
16th to endDay
6%6%47%6%48%8%9%12%25%
2276
August1st to 15thDay
8%5%25%7%5%8%9%9%12%25%
2160
16th to endDay
10%7%36%7%47%6%7%10%28%
2292
September1st to 15thDay
8%5%26%6%5%7%7%7%8%32%
2094
16th to endDay
6%426%5%36%5%6%8%44%
1848
October1st to 15thDay
5%3135%3446%8%53%
1815
16th to endDay
7%41342345%5%56%
1811
November1st to 15thDay
8%413323447%55%
1593
16th to endDay
6%41442235%7%56%
1620
December1st to 15thDay
11%5%26%6%1445%7%45%
1620
16th to endDay
18%7%36%5%33446%34%
1728
January1st to 15thNight
11%6%24335%45%6%45%
2181
16th to endNight
17%7%2442334444%
2304
February1st to 15thNight
14%41331435%5%51%
2103
16th to endNight
15%6%35%42435%5%44%
1893
March1st to 15thNight
12%5%15%5%2445%7%44%
2160
16th to endNight
9%5%24324446%53%
2013
April1st to 15thNight
9%41442445%8%49%
1797
16th to endNight
7%31332245%8%58%
1800
May1st to 15thNight
7%32432445%10%51%
1784
16th to endNight
4323435%5%6%10%50%
1682
June1st to 15thNight
5%325%435%5%7%13%43%
1620
16th to endNight
5%3245%36%5%8%13%41%
1620
July1st to 15thNight
3324436%6%8%13%42%
1673
16th to endNight
3225%6%36%8%8%14%38%
1892
August1st to 15thNight
32145%36%8%10%15%38%
1800
16th to endNight
7%425%5%346%7%12%38%
1910
September1st to 15thNight
5%425%445%7%7%12%40%
1851
16th to endNight
8%4245%345%6%8%46%
1858
October1st to 15thNight
4313324348%59%
1815
16th to endNight
8%413322336%60%
2059
November1st to 15thNight
7%424424346%55%
2264
16th to endNight
7%424324446%55%
2340
December1st to 15thNight
10%5%35%424346%47%
2340
16th to endNight
16%8%35%42335%6%38%
2496

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
36%5%8%16%23%9%
1756
16th to endDay
41%45%15%23%9%
1920
February1st to 15thDay
35%49%17%22%10%
1752
16th to endDay
39%6%6%16%22%7%
1580
March1st to 15thDay
38%5%8%21%19%6%
1800
16th to endDay
34%6%12%19%19%7%
2219
April1st to 15thDay
36%49%20%20%7%
2151
16th to endDay
28%7%12%24%20%6%
2160
May1st to 15thDay
32%7%13%20%18%7%
2163
16th to endDay
33%8%14%24%16%2
2435
June1st to 15thDay
38%12%16%22%9%
2340
16th to endDay
39%12%17%19%9%
2340
July1st to 15thDay
47%16%18%14%3
2149
16th to endDay
45%15%18%18%2
2133
August1st to 15thDay
42%15%22%13%6%
2148
16th to endDay
47%12%17%14%6%2
2292
September1st to 15thDay
43%10%16%12%11%4
2094
16th to endDay
36%8%13%17%16%7%
1848
October1st to 15thDay
27%5%11%17%22%15%
1815
16th to endDay
28%46%13%26%20%
1811
November1st to 15thDay
28%47%19%27%12%
1593
16th to endDay
27%6%8%17%23%16%
1620
December1st to 15thDay
38%5%9%19%20%6%
1620
16th to endDay
49%47%18%14%5%
1728
January1st to 15thNight
37%5%8%13%25%9%
2181
16th to endNight
42%36%13%23%9%
2304
February1st to 15thNight
34%36%19%22%13%
2112
16th to endNight
41%46%14%20%12%
1893
March1st to 15thNight
38%411%17%20%7%
2160
16th to endNight
31%5%10%22%20%9%
2013
April1st to 15thNight
31%5%12%17%22%9%
1797
16th to endNight
24%413%29%21%7%
1800
May1st to 15thNight
28%5%15%21%21%7%
1785
16th to endNight
27%8%17%24%19%2
1684
June1st to 15thNight
28%9%24%23%12%1
1620
16th to endNight
31%10%24%22%10%
1620
July1st to 15thNight
28%14%32%17%6%
1579
16th to endNight
30%15%29%20%2
1772
August1st to 15thNight
28%15%32%18%4
1788
16th to endNight
37%12%24%16%6%3
1910
September1st to 15thNight
32%12%20%17%12%5%
1851
16th to endNight
32%7%16%19%16%7%
1858
October1st to 15thNight
23%411%21%22%16%
1815
16th to endNight
26%35%15%26%22%
2059
November1st to 15thNight
30%46%17%28%13%
2264
16th to endNight
28%5%7%17%21%18%
2340
December1st to 15thNight
37%5%8%21%21%6%
2340
16th to endNight
45%48%20%15%6%
2496

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
15%10%26%30%12%5%
90
16th to endDay
19%10%36%21%10%1
96
February1st to 15thDay
10%11%32%27%15%3
90
16th to endDay
11%6%38%27%16%1
81
March1st to 15thDay
21%336%30%7%1
90
16th to endDay
16%322%29%24%3
257
April1st to 15thDay
14%7%22%28%24%3
270
16th to endDay
7%317%32%30%8%
270
May1st to 15thDay
7%217%26%34%11%
288
16th to endDay
8%111%24%29%24%
331
June1st to 15thDay
13%316%33%31%
315
16th to endDay
10%5%10%33%39%
315
July1st to 15thDay
7%8%30%53%
305
16th to endDay
7%19%32%47%
326
August1st to 15thDay
13%9%31%44%
313
16th to endDay
10%19%33%43%
332
September1st to 15thDay
9%18%15%31%33%
315
16th to endDay
10%5%22%39%21%
266
October1st to 15thDay
5%11%29%36%17%
255
16th to endDay
11%311%31%24%17%
147
November1st to 15thDay
22%211%30%30%4
90
16th to endDay
6%425%37%20%5%
90
December1st to 15thDay
14%331%31%13%6%
90
16th to endDay
28%6%20%26%16%2
96
January1st to 15thNight
13%5%31%38%10%
720
16th to endNight
20%8%28%30%11%
768
February1st to 15thNight
16%5%30%34%13%
704
16th to endNight
16%7%33%33%9%
631
March1st to 15thNight
14%5%29%37%12%1
720
16th to endNight
12%420%36%23%2
639
April1st to 15thNight
11%321%38%23%1
539
16th to endNight
9%116%38%30%2
540
May1st to 15thNight
8%311%38%33%4
540
16th to endNight
5%7%30%46%9%
563
June1st to 15thNight
7%420%52%15%
540
16th to endNight
7%1214%48%27%
540
July1st to 15thNight
319%49%36%
510
16th to endNight
328%48%36%
564
August1st to 15thNight
415%48%39%
539
16th to endNight
9%411%46%27%
573
September1st to 15thNight
8%16%16%43%24%
591
16th to endNight
10%5%27%45%10%
673
October1st to 15thNight
7%11%36%37%7%
660
16th to endNight
10%217%33%29%6%
704
November1st to 15thNight
9%417%39%25%4
700
16th to endNight
9%425%37%19%3
720
December1st to 15thNight
13%5%26%33%18%2
720
16th to endNight
20%5%26%31%14%1
768
Page generated at 2017-09-20 03:49:44. Version ac04

Copyright 2017 A. Danko


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