Anna City Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Anna City Park clear sky chart from 2005-11-05 to 2018-01-12.

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
41%
16253
22%
48346
14%
16207
49%
16207
28%
30099

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
22%
956
20%
2662
8%
951
32%
951
22%
1758
January16th to endNight
21%
960
20%
2496
6%
960
30%
960
25%
1690
February1st to 15thNight
18%
757
17%
2165
6%
754
27%
754
18%
1500
February16th to endNight
20%
631
19%
1893
6%
631
31%
631
19%
1252
March1st to 15thNight
21%
708
16%
2148
7%
708
29%
708
19%
1466
March16th to endNight
31%
576
16%
1999
10%
576
39%
576
20%
1301
April1st to 15thNight
30%
539
23%
1797
12%
539
47%
539
28%
1036
April16th to endNight
39%
540
22%
1800
15%
540
50%
540
25%
1116
May1st to 15thNight
39%
539
18%
1676
11%
539
47%
539
25%
1087
May16th to endNight
50%
563
19%
1555
14%
561
54%
561
30%
1022
June1st to 15thNight
64%
540
22%
1440
16%
540
67%
540
41%
857
June16th to endNight
69%
540
25%
1440
17%
540
73%
540
43%
825
July1st to 15thNight
68%
510
18%
1360
14%
510
70%
510
38%
832
July16th to endNight
76%
564
23%
1469
20%
531
79%
531
42%
840
August1st to 15thNight
76%
539
23%
1753
27%
536
77%
536
41%
923
August16th to endNight
74%
573
25%
1910
29%
573
76%
573
36%
1059
September1st to 15thNight
63%
540
26%
1800
25%
540
67%
540
31%
1035
September16th to endNight
60%
699
31%
1962
23%
699
65%
699
37%
1149
October1st to 15thNight
53%
720
30%
2091
22%
720
60%
720
37%
1203
October16th to endNight
37%
768
29%
2346
18%
768
49%
768
31%
1379
November1st to 15thNight
39%
760
29%
2471
20%
760
52%
760
31%
1396
November16th to endNight
34%
780
26%
2535
18%
780
45%
780
26%
1522
December1st to 15thNight
28%
911
18%
2666
9%
911
37%
911
22%
1794
December16th to endNight
20%
1040
19%
2912
6%
1040
31%
1040
19%
2057

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
12%5%25%5%3445%7%42%
48993
Night
13%5%24424446%46%
48526
TransparencyDay
40%6%12%23%15%2
48677
Night
37%5%11%23%17%3
48348
SeeingDay
14%8%24%26%18%8%
6155
Night
16%9%28%27%15%2
16254

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
20%6%25%5%23345%38%
1520
16th to endDay
14%6%36%6%33446%40%
1725
February1st to 15thDay
15%8%46%424445%38%
1696
16th to endDay
13%10%36%5%345%5%6%36%
1580
March1st to 15thDay
20%8%25%424435%37%
1821
16th to endDay
18%7%36%5%34447%33%
2221
April1st to 15thDay
14%5%2432436%6%45%
2151
16th to endDay
18%7%35%5%34447%37%
2160
May1st to 15thDay
17%5%25%5%35%45%7%36%
2271
16th to endDay
10%5%26%6%35%5%6%8%37%
2556
June1st to 15thDay
7%4145%35%5%6%9%44%
2520
16th to endDay
5%3245%36%5%6%10%45%
2520
July1st to 15thDay
8%4346%36%46%10%40%
2520
16th to endDay
42145%46%7%8%10%44%
2596
August1st to 15thDay
6%425%6%35%5%7%10%41%
2196
16th to endDay
8%4245%35%6%7%10%42%
2292
September1st to 15thDay
11%5%245%2445%7%44%
2160
16th to endDay
10%4245%2445%7%49%
1986
October1st to 15thDay
11%424423347%50%
1866
16th to endDay
14%314323445%51%
1878
November1st to 15thDay
13%5%235%23335%49%
1717
16th to endDay
19%7%2431233446%
1755
December1st to 15thDay
19%8%23324445%40%
1622
16th to endDay
19%9%36%433336%35%
1664
January1st to 15thNight
19%7%24413346%42%
2662
16th to endNight
14%6%25%424446%43%
2496
February1st to 15thNight
17%8%36%433435%38%
2156
16th to endNight
14%7%35%5%34345%41%
1893
March1st to 15thNight
19%7%35%5%2443439%
2148
16th to endNight
17%5%35%5%24446%40%
1999
April1st to 15thNight
11%6%25%32335%7%48%
1797
16th to endNight
18%415%414337%44%
1800
May1st to 15thNight
15%6%335%24448%42%
1676
16th to endNight
7%435%7%36%45%9%41%
1554
June1st to 15thNight
6%31442446%9%51%
1440
16th to endNight
3213327%5%7%12%50%
1440
July1st to 15thNight
6%425%335%448%51%
1440
16th to endNight
5%3144345%7%10%50%
1569
August1st to 15thNight
5%21342346%10%54%
1763
16th to endNight
5%41333446%9%51%
1910
September1st to 15thNight
9%425%4245%46%50%
1800
16th to endNight
10%313323335%55%
1962
October1st to 15thNight
8%5%14323447%53%
2091
16th to endNight
15%5%1432223353%
2346
November1st to 15thNight
12%5%24322446%51%
2471
16th to endNight
17%6%24413235%49%
2535
December1st to 15thNight
20%7%24423345%40%
2666
16th to endNight
21%8%35%323335%38%
2912

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
47%410%23%11%2
1521
16th to endDay
44%5%12%26%9%
1725
February1st to 15thDay
47%5%11%23%10%1
1698
16th to endDay
47%5%12%20%11%2
1580
March1st to 15thDay
49%47%22%11%2
1821
16th to endDay
50%6%14%20%7%
2223
April1st to 15thDay
38%5%11%23%18%1
2151
16th to endDay
47%5%11%23%11%1
2160
May1st to 15thDay
46%7%12%20%12%
2271
16th to endDay
42%9%14%18%12%2
2560
June1st to 15thDay
32%8%14%25%17%1
2520
16th to endDay
31%8%14%22%20%3
2520
July1st to 15thDay
37%8%13%21%14%4
2371
16th to endDay
29%10%18%27%13%2
2434
August1st to 15thDay
35%9%13%23%15%2
2182
16th to endDay
33%7%15%21%16%4
2292
September1st to 15thDay
36%6%10%23%19%3
2160
16th to endDay
33%6%8%24%23%3
1986
October1st to 15thDay
33%5%11%23%20%5%
1866
16th to endDay
34%47%30%18%4
1878
November1st to 15thDay
36%49%21%20%7%
1717
16th to endDay
42%37%25%18%2
1755
December1st to 15thDay
44%413%21%13%1
1622
16th to endDay
51%412%19%10%1
1664
January1st to 15thNight
43%411%22%16%2
2662
16th to endNight
41%5%13%23%13%1
2496
February1st to 15thNight
48%49%22%12%2
2165
16th to endNight
44%5%12%22%13%1
1893
March1st to 15thNight
48%410%17%14%4
2148
16th to endNight
44%5%14%22%10%1
1999
April1st to 15thNight
34%412%26%18%3
1797
16th to endNight
40%48%25%17%3
1800
May1st to 15thNight
40%7%13%22%15%1
1677
16th to endNight
37%7%14%21%14%3
1556
June1st to 15thNight
27%6%15%25%21%2
1440
16th to endNight
24%7%15%24%20%6%
1440
July1st to 15thNight
31%6%15%24%14%7%
1360
16th to endNight
25%6%17%30%17%1
1469
August1st to 15thNight
23%7%16%27%22%2
1753
16th to endNight
27%7%14%24%20%5%
1910
September1st to 15thNight
33%6%8%26%18%6%
1800
16th to endNight
31%5%8%24%24%6%
1962
October1st to 15thNight
30%410%20%27%6%
2091
16th to endNight
35%37%25%22%6%
2346
November1st to 15thNight
32%49%23%21%7%
2471
16th to endNight
38%38%24%22%2
2535
December1st to 15thNight
45%5%11%20%15%1
2666
16th to endNight
49%5%11%20%11%2
2912

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
33%20%30%10%5%
123
16th to endDay
12%31%43%11%1
96
February1st to 15thDay
18%30%37%12%1
90
16th to endDay
22%24%38%12%2
81
March1st to 15thDay
32%13%37%13%3
90
16th to endDay
21%15%34%21%5%
207
April1st to 15thDay
16%16%32%24%8%1
270
16th to endDay
21%10%31%24%9%2
270
May1st to 15thDay
20%13%28%22%12%2
288
16th to endDay
14%6%30%30%13%6%
456
June1st to 15thDay
10%321%30%22%11%
495
16th to endDay
6%426%38%17%7%
495
July1st to 15thDay
12%219%32%23%10%
475
16th to endDay
5%112%31%32%17%
515
August1st to 15thDay
9%111%27%33%16%
349
16th to endDay
14%112%26%31%13%
332
September1st to 15thDay
10%413%22%34%13%
315
16th to endDay
11%5%12%25%29%15%
314
October1st to 15thDay
14%425%33%14%5%
201
16th to endDay
13%13%31%31%8%
144
November1st to 15thDay
12%14%30%22%15%5%
135
16th to endDay
28%13%28%22%6%
135
December1st to 15thDay
14%17%41%17%43
135
16th to endDay
31%24%36%6%1
144
January1st to 15thNight
24%18%32%21%3
956
16th to endNight
17%17%40%22%2
960
February1st to 15thNight
22%19%35%21%1
757
16th to endNight
19%19%37%22%1
631
March1st to 15thNight
21%16%38%20%3
708
16th to endNight
19%10%34%26%9%
576
April1st to 15thNight
15%13%38%24%8%
539
16th to endNight
18%7%31%31%10%
540
May1st to 15thNight
17%6%30%31%12%1
540
16th to endNight
9%325%36%22%2
563
June1st to 15thNight
9%219%38%28%2
540
16th to endNight
5%18%46%25%2
540
July1st to 15thNight
10%12%39%33%3
510
16th to endNight
5%19%33%41%9%
564
August1st to 15thNight
6%10%34%41%7%
539
16th to endNight
8%110%34%40%4
573
September1st to 15thNight
10%115%27%36%7%
540
16th to endNight
12%318%27%31%6%
699
October1st to 15thNight
11%5%25%29%21%5%
720
16th to endNight
18%8%33%26%11%1
768
November1st to 15thNight
14%10%31%28%13%
760
16th to endNight
18%14%30%26%9%
780
December1st to 15thNight
23%11%33%24%6%
911
16th to endNight
24%14%36%20%3
1040
Page generated at 2018-01-12 21:01:37. Version ac04

Copyright 2018 A. Danko


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