This page made possible by the sponsorship of:

Charlotte Amateur Astronomers Club
, Souder Properties.

Charlotte
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Charlotte clear sky chart from 2005-11-05 to 2018-03-11.

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
50%
16492
23%
49058
16%
16454
58%
16454
29%
30606

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
35%
778
23%
2522
12%
776
49%
776
26%
1539
January16th to endNight
34%
832
26%
2704
15%
832
49%
832
27%
1621
February1st to 15thNight
32%
761
22%
2443
12%
761
46%
761
27%
1484
February16th to endNight
29%
683
27%
2010
12%
683
44%
683
30%
1234
March1st to 15thNight
37%
764
26%
2101
15%
764
47%
764
33%
1283
March16th to endNight
40%
768
21%
2112
12%
768
47%
768
28%
1375
April1st to 15thNight
44%
718
23%
1913
12%
718
52%
718
35%
1188
April16th to endNight
49%
645
23%
1725
14%
645
54%
645
35%
1072
May1st to 15thNight
50%
540
17%
1620
9%
540
56%
540
28%
1032
May16th to endNight
64%
561
18%
1684
14%
561
65%
561
29%
1065
June1st to 15thNight
65%
540
15%
1620
13%
540
67%
540
26%
1072
June16th to endNight
70%
540
16%
1620
13%
540
71%
540
27%
1060
July1st to 15thNight
71%
510
11%
1530
9%
510
71%
510
25%
1026
July16th to endNight
71%
564
14%
1595
12%
531
73%
531
28%
1031
August1st to 15thNight
67%
539
15%
1609
14%
536
68%
536
25%
1087
August16th to endNight
69%
672
18%
1818
14%
672
69%
672
27%
1242
September1st to 15thNight
70%
720
20%
1952
18%
720
71%
720
32%
1253
September16th to endNight
55%
717
20%
1980
17%
717
57%
717
24%
1375
October1st to 15thNight
57%
720
28%
2118
27%
720
62%
720
34%
1259
October16th to endNight
54%
768
35%
2304
27%
768
66%
768
38%
1274
November1st to 15thNight
52%
760
29%
2304
23%
760
61%
760
36%
1304
November16th to endNight
50%
780
29%
2535
23%
780
60%
780
32%
1436
December1st to 15thNight
43%
780
24%
2535
17%
780
53%
780
25%
1564
December16th to endNight
39%
832
24%
2704
18%
832
48%
832
23%
1730

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
13%5%2442445%7%44%
49563
Night
13%5%2442445%7%44%
49256
TransparencyDay
37%6%11%21%18%4
49264
Night
37%5%11%20%19%6%
49059
SeeingDay
16%417%23%23%14%
6229
Night
15%421%32%22%3
16499

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
17%7%24423445%44%
1746
16th to endDay
16%5%2332344449%
1872
February1st to 15thDay
16%5%2232445%6%45%
1745
16th to endDay
16%6%13323346%47%
1747
March1st to 15thDay
14%5%2331435%6%48%
2096
16th to endDay
17%423324447%44%
2111
April1st to 15thDay
11%41332445%8%51%
2033
16th to endDay
14%423424445%47%
2244
May1st to 15thDay
11%435%5%35%46%8%41%
2331
16th to endDay
9%6%145%35%45%8%45%
2431
June1st to 15thDay
9%425%425%6%7%10%40%
2340
16th to endDay
5%325%435%6%6%11%43%
2340
July1st to 15thDay
9%5%35%6%35%7%7%11%34%
2340
16th to endDay
6%3245%46%7%8%12%36%
2465
August1st to 15thDay
12%5%245%37%5%9%10%33%
2340
16th to endDay
11%5%26%6%45%6%7%11%32%
2372
September1st to 15thDay
9%413425%46%9%45%
2005
16th to endDay
16%5%245%25%446%41%
1980
October1st to 15thDay
15%5%1322233455%
1842
16th to endDay
12%41431233359%
1920
November1st to 15thDay
13%413312336%54%
1881
16th to endDay
14%423323345%52%
1755
December1st to 15thDay
16%7%24323447%43%
1755
16th to endDay
18%8%2342345%5%41%
1872
January1st to 15thNight
15%5%2442433448%
2522
16th to endNight
16%5%24323345%48%
2704
February1st to 15thNight
16%425%423345%47%
2435
16th to endNight
14%5%235%23446%46%
2010
March1st to 15thNight
14%42422345%6%49%
2101
16th to endNight
16%425%33445%6%43%
2112
April1st to 15thNight
11%5%13425%347%50%
1913
16th to endNight
13%424425%45%6%48%
1725
May1st to 15thNight
10%5%36%5%345%5%8%41%
1619
16th to endNight
10%425%5%35%5%5%8%42%
1682
June1st to 15thNight
11%425%6%36%5%7%11%35%
1620
16th to endNight
5%425%6%5%6%7%7%11%38%
1620
July1st to 15thNight
7%435%5%46%7%10%11%32%
1620
16th to endNight
5%435%6%37%6%9%11%36%
1703
August1st to 15thNight
8%6%36%6%35%6%7%11%34%
1620
16th to endNight
7%6%36%5%45%6%8%10%35%
1818
September1st to 15thNight
8%5%24425%5%6%10%42%
1952
16th to endNight
18%5%245%2445%6%38%
1980
October1st to 15thNight
14%5%24323235%52%
2118
16th to endNight
11%41231333458%
2304
November1st to 15thNight
13%413213345%54%
2304
16th to endNight
12%314424346%51%
2535
December1st to 15thNight
17%6%24324445%44%
2535
16th to endNight
19%6%2442435%6%40%
2704

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%36%19%21%4
1747
16th to endDay
37%27%21%21%9%
1872
February1st to 15thDay
39%39%21%21%5%
1747
16th to endDay
38%48%25%19%4
1747
March1st to 15thDay
35%5%7%22%22%7%
2096
16th to endDay
39%5%11%22%18%3
2112
April1st to 15thDay
30%410%26%22%5%
2033
16th to endDay
37%49%20%20%7%
2244
May1st to 15thDay
38%6%14%22%16%1
2331
16th to endDay
37%6%15%24%13%2
2435
June1st to 15thDay
36%8%16%25%12%
2340
16th to endDay
32%8%18%23%15%1
2340
July1st to 15thDay
39%10%17%19%9%2
2201
16th to endDay
34%11%19%21%11%1
2310
August1st to 15thDay
42%9%15%20%10%1
2327
16th to endDay
42%9%16%19%10%1
2372
September1st to 15thDay
33%8%14%20%18%3
2005
16th to endDay
42%6%8%19%18%4
1980
October1st to 15thDay
33%38%24%25%5%
1842
16th to endDay
29%35%22%30%8%
1920
November1st to 15thDay
31%38%20%28%7%
1881
16th to endDay
34%37%20%25%7%
1755
December1st to 15thDay
40%39%23%18%4
1755
16th to endDay
44%410%19%16%5%
1872
January1st to 15thNight
38%48%15%24%7%
2522
16th to endNight
38%35%20%24%7%
2704
February1st to 15thNight
39%27%20%22%6%
2444
16th to endNight
37%310%22%21%4
2010
March1st to 15thNight
34%49%19%22%8%
2101
16th to endNight
40%410%20%18%5%
2112
April1st to 15thNight
34%48%22%23%6%
1913
16th to endNight
35%411%19%20%9%
1725
May1st to 15thNight
38%6%14%21%16%3
1620
16th to endNight
37%6%14%25%13%1
1684
June1st to 15thNight
40%7%16%24%9%1
1620
16th to endNight
36%11%15%21%11%4
1620
July1st to 15thNight
37%11%18%18%9%3
1530
16th to endNight
36%10%21%20%9%2
1595
August1st to 15thNight
40%9%18%18%11%1
1609
16th to endNight
38%10%18%21%9%1
1818
September1st to 15thNight
35%8%15%19%16%4
1952
16th to endNight
44%7%10%14%18%3
1980
October1st to 15thNight
34%49%21%24%5%
2118
16th to endNight
30%26%20%26%13%
2304
November1st to 15thNight
32%37%18%25%13%
2304
16th to endNight
33%36%19%27%9%
2535
December1st to 15thNight
40%48%19%20%6%
2535
16th to endNight
44%39%18%17%5%
2704

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
22%11%28%28%8%
135
16th to endDay
18%17%32%15%12%2
144
February1st to 15thDay
21%12%45%18%2
135
16th to endDay
22%8%33%25%8%
157
March1st to 15thDay
15%9%36%27%11%
312
16th to endDay
19%5%30%30%12%1
288
April1st to 15thDay
15%8%24%27%19%5%
270
16th to endDay
18%318%28%21%9%
270
May1st to 15thDay
16%325%26%19%8%
288
16th to endDay
15%210%20%28%23%
331
June1st to 15thDay
13%18%23%30%22%
315
16th to endDay
10%11%20%31%24%
315
July1st to 15thDay
10%8%17%35%27%
305
16th to endDay
8%15%15%37%30%
326
August1st to 15thDay
16%16%16%30%27%
313
16th to endDay
12%7%20%26%31%
332
September1st to 15thDay
16%17%20%31%23%
315
16th to endDay
19%211%21%28%16%
314
October1st to 15thDay
20%113%26%25%11%
315
16th to endDay
12%316%30%22%13%
336
November1st to 15thDay
20%318%29%21%6%
299
16th to endDay
8%5%21%32%24%7%
135
December1st to 15thDay
22%6%30%26%13%
135
16th to endDay
22%6%38%23%8%
144
January1st to 15thNight
19%7%32%32%8%
780
16th to endNight
19%6%35%32%5%
832
February1st to 15thNight
19%7%36%34%2
764
16th to endNight
16%8%39%30%5%
683
March1st to 15thNight
15%8%32%35%7%
764
16th to endNight
18%6%27%35%11%
768
April1st to 15thNight
15%7%29%31%14%
718
16th to endNight
17%424%32%21%
645
May1st to 15thNight
12%423%40%18%1
540
16th to endNight
11%112%33%37%3
563
June1st to 15thNight
13%18%33%34%7%
540
16th to endNight
7%8%29%45%7%
540
July1st to 15thNight
10%1430%44%9%
510
16th to endNight
7%1425%50%10%
564
August1st to 15thNight
12%1425%49%7%
539
16th to endNight
10%426%48%8%
672
September1st to 15thNight
11%15%28%44%8%
720
16th to endNight
23%10%27%33%4
717
October1st to 15thNight
17%216%29%28%5%
720
16th to endNight
13%422%32%23%3
768
November1st to 15thNight
15%323%33%20%3
760
16th to endNight
14%5%25%34%18%1
780
December1st to 15thNight
19%5%24%37%11%
780
16th to endNight
22%5%25%37%8%
832
Page generated at 2018-03-12 13:28:02. Version ac04

Copyright 2018 A. Danko


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