Phenix City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Phenix City clear sky chart from 2005-11-05 to 2017-04-30.

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
45%
15013
23%
45647
15%
14970
55%
14970
26%
27971

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
25%
720
24%
2327
10%
716
43%
716
21%
1426
January16th to endNight
30%
768
25%
2373
13%
768
42%
768
23%
1490
February1st to 15thNight
33%
703
26%
2110
13%
700
46%
700
25%
1274
February16th to endNight
26%
631
25%
1893
9%
631
42%
631
26%
1172
March1st to 15thNight
33%
720
24%
2085
12%
720
44%
720
26%
1268
March16th to endNight
36%
768
23%
2112
10%
768
46%
768
28%
1301
April1st to 15thNight
43%
604
25%
1862
18%
604
52%
604
29%
1067
April16th to endNight
46%
537
28%
1750
17%
537
59%
537
30%
936
May1st to 15thNight
48%
494
24%
1485
14%
494
57%
494
28%
892
May16th to endNight
53%
513
21%
1538
12%
513
61%
513
26%
930
June1st to 15thNight
59%
495
15%
1485
12%
495
62%
495
22%
975
June16th to endNight
68%
495
19%
1485
15%
495
70%
495
29%
908
July1st to 15thNight
66%
465
12%
1395
11%
465
67%
465
23%
949
July16th to endNight
65%
522
14%
1469
14%
489
71%
489
25%
971
August1st to 15thNight
65%
494
16%
1589
17%
491
66%
491
22%
1047
August16th to endNight
60%
525
15%
1750
17%
525
62%
525
20%
1178
September1st to 15thNight
62%
630
19%
1785
17%
630
63%
630
24%
1229
September16th to endNight
52%
657
23%
1815
13%
657
60%
657
24%
1205
October1st to 15thNight
54%
660
33%
1815
24%
660
62%
660
37%
1038
October16th to endNight
52%
704
35%
2076
27%
704
63%
704
39%
1123
November1st to 15thNight
46%
700
30%
2272
24%
700
57%
700
32%
1220
November16th to endNight
40%
720
28%
2340
17%
720
55%
720
28%
1319
December1st to 15thNight
37%
720
24%
2340
16%
720
49%
720
22%
1401
December16th to endNight
29%
768
20%
2496
10%
768
42%
768
18%
1652

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%35%5%5%8%42%
46070
Night
11%42442445%7%46%
45848
TransparencyDay
39%7%11%17%17%6%
45771
Night
35%6%10%18%19%8%
45651
SeeingDay
13%12%15%21%22%14%
4789
Night
12%18%17%26%21%4
15017

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
15%5%25%5%23345%46%
1611
16th to endDay
16%5%25%423346%44%
1848
February1st to 15thDay
15%5%25%424346%45%
1750
16th to endDay
15%6%24323346%45%
1580
March1st to 15thDay
13%6%25%434445%46%
1873
16th to endDay
13%5%24325%45%6%45%
2111
April1st to 15thDay
11%4345%24447%46%
2095
16th to endDay
10%3144245%47%51%
2188
May1st to 15thDay
9%425%435%5%49%45%
2136
16th to endDay
7%3135%35%6%7%10%43%
2223
June1st to 15thDay
9%425%7%36%8%8%11%33%
2145
16th to endDay
43235%47%7%8%12%40%
2145
July1st to 15thDay
11%5%35%7%5%7%7%8%10%26%
2145
16th to endDay
8%6%37%6%47%7%8%11%27%
2283
August1st to 15thDay
10%425%6%48%8%9%12%28%
2027
16th to endDay
14%5%26%6%36%7%7%8%29%
2100
September1st to 15thDay
11%6%26%7%36%6%6%8%34%
1833
16th to endDay
14%5%26%6%34446%40%
1815
October1st to 15thDay
11%5%24323347%51%
1815
16th to endDay
10%413322235%60%
1795
November1st to 15thDay
10%4243235%36%55%
1584
16th to endDay
13%414324336%52%
1620
December1st to 15thDay
14%5%2443335%6%45%
1620
16th to endDay
22%8%35%5%23335%36%
1728
January1st to 15thNight
15%6%24423346%46%
2327
16th to endNight
18%5%24423435%45%
2373
February1st to 15thNight
14%414423346%48%
2103
16th to endNight
14%5%2442434449%
1893
March1st to 15thNight
11%5%2442335%5%50%
2085
16th to endNight
11%42442335%8%49%
2112
April1st to 15thNight
11%41332445%8%50%
1862
16th to endNight
8%31432335%7%55%
1750
May1st to 15thNight
8%3235%345%5%8%49%
1484
16th to endNight
5%415%5%345%6%8%48%
1538
June1st to 15thNight
5%425%5%46%7%9%8%39%
1485
16th to endNight
22235%35%7%9%14%41%
1485
July1st to 15thNight
4326%6%36%8%10%13%33%
1485
16th to endNight
7%3145%37%7%9%14%34%
1577
August1st to 15thNight
7%4246%36%6%8%14%34%
1600
16th to endNight
11%6%25%5%35%5%6%10%34%
1750
September1st to 15thNight
10%5%25%5%46%5%6%9%38%
1785
16th to endNight
10%5%36%5%3445%6%43%
1815
October1st to 15thNight
10%313313446%56%
1815
16th to endNight
9%413312335%60%
2076
November1st to 15thNight
11%21442233458%
2272
16th to endNight
13%413223346%54%
2340
December1st to 15thNight
13%6%25%424347%47%
2340
16th to endNight
21%5%25%434346%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
40%47%15%25%6%
1612
16th to endDay
41%46%14%23%8%
1848
February1st to 15thDay
40%45%19%22%7%
1752
16th to endDay
41%45%16%22%8%
1580
March1st to 15thDay
40%49%17%20%7%
1873
16th to endDay
37%5%11%19%20%5%
2112
April1st to 15thDay
36%5%8%21%19%8%
2095
16th to endDay
32%6%10%20%24%5%
2188
May1st to 15thDay
35%8%12%18%19%5%
2136
16th to endDay
32%11%14%25%13%4
2227
June1st to 15thDay
40%12%15%19%9%1
2145
16th to endDay
31%11%18%21%13%2
2145
July1st to 15thDay
46%14%19%12%42
2006
16th to endDay
45%13%18%15%6%
2128
August1st to 15thDay
42%14%18%17%7%
2014
16th to endDay
48%11%15%13%9%
2100
September1st to 15thDay
44%10%14%13%12%3
1833
16th to endDay
43%6%9%18%17%4
1815
October1st to 15thDay
32%410%18%24%9%
1815
16th to endDay
27%36%16%29%16%
1795
November1st to 15thDay
31%46%16%26%15%
1584
16th to endDay
34%47%15%25%12%
1620
December1st to 15thDay
39%5%10%18%19%7%
1620
16th to endDay
51%36%16%14%6%
1728
January1st to 15thNight
39%46%16%25%8%
2327
16th to endNight
41%36%14%22%11%
2373
February1st to 15thNight
37%26%18%20%13%
2112
16th to endNight
37%46%16%22%12%
1893
March1st to 15thNight
34%5%8%20%21%9%
2085
16th to endNight
33%5%10%19%23%7%
2112
April1st to 15thNight
31%5%10%19%22%10%
1862
16th to endNight
28%5%10%24%21%10%
1750
May1st to 15thNight
31%7%12%18%23%5%
1485
16th to endNight
31%8%14%23%16%6%
1540
June1st to 15thNight
36%10%17%21%13%
1485
16th to endNight
27%12%18%22%14%3
1485
July1st to 15thNight
34%16%23%17%5%2
1395
16th to endNight
34%13%23%20%7%
1469
August1st to 15thNight
34%14%19%20%7%2
1589
16th to endNight
41%11%17%14%12%2
1750
September1st to 15thNight
39%10%12%18%14%3
1785
16th to endNight
40%7%9%18%18%6%
1815
October1st to 15thNight
28%411%20%21%13%
1815
16th to endNight
27%25%14%30%18%
2076
November1st to 15thNight
29%36%15%27%17%
2272
16th to endNight
32%47%15%25%14%
2340
December1st to 15thNight
38%49%19%21%7%
2340
16th to endNight
46%47%17%16%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
23%11%35%15%7%6%
90
16th to endDay
13%21%44%12%6%1
96
February1st to 15thDay
17%22%35%17%6%
90
16th to endDay
13%17%38%27%3
81
March1st to 15thDay
14%20%38%15%8%1
163
16th to endDay
15%16%27%26%12%1
288
April1st to 15thDay
14%20%19%21%21%1
270
16th to endDay
13%13%16%25%24%6%
266
May1st to 15thDay
12%16%23%18%18%10%
228
16th to endDay
9%12%8%20%28%21%
267
June1st to 15thDay
9%12%6%16%26%29%
255
16th to endDay
312%5%18%24%36%
255
July1st to 15thDay
8%9%219%28%31%
245
16th to endDay
8%11%310%33%32%
270
August1st to 15thDay
13%7%218%30%26%
253
16th to endDay
15%5%219%32%23%
268
September1st to 15thDay
12%6%7%15%32%25%
255
16th to endDay
16%6%7%32%29%6%
254
October1st to 15thDay
13%9%15%29%25%6%
255
16th to endDay
11%9%19%27%22%9%
272
November1st to 15thDay
21%5%28%28%14%2
92
16th to endDay
412%35%27%16%3
90
December1st to 15thDay
18%14%37%20%6%2
90
16th to endDay
39%7%12%34%5%1
96
January1st to 15thNight
16%25%27%21%7%
720
16th to endNight
14%23%28%26%5%
768
February1st to 15thNight
13%23%25%30%6%
704
16th to endNight
14%20%33%25%4
631
March1st to 15thNight
12%25%26%28%7%
720
16th to endNight
11%24%23%26%13%
768
April1st to 15thNight
12%19%21%26%19%
604
16th to endNight
8%19%19%25%25%
537
May1st to 15thNight
8%20%18%27%22%3
495
16th to endNight
7%19%11%25%31%4
515
June1st to 15thNight
8%18%423%35%8%
495
16th to endNight
318%419%41%13%
495
July1st to 15thNight
6%13%222%40%15%
465
16th to endNight
7%18%215%41%14%
522
August1st to 15thNight
8%10%324%40%13%
494
16th to endNight
14%9%6%20%35%13%
525
September1st to 15thNight
11%9%6%21%38%11%
630
16th to endNight
13%9%12%32%29%2
657
October1st to 15thNight
12%11%15%32%25%3
660
16th to endNight
10%11%20%27%26%2
704
November1st to 15thNight
11%18%19%29%18%2
700
16th to endNight
12%20%23%30%12%1
720
December1st to 15thNight
15%21%22%27%12%1
720
16th to endNight
21%22%23%26%5%
768
Page generated at 2017-04-30 19:40:08. Version ac04

Copyright 2017 A. Danko


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