Congaree National Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Congaree National Park 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
50%
15397
22%
45605
15%
15356
57%
15356
28%
28636

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
34%
718
21%
2327
11%
716
48%
716
24%
1422
January16th to endNight
31%
768
24%
2496
15%
768
44%
768
24%
1536
February1st to 15thNight
33%
704
23%
2229
12%
701
48%
701
26%
1364
February16th to endNight
31%
631
27%
1845
13%
631
45%
631
30%
1128
March1st to 15thNight
37%
720
26%
1980
14%
720
46%
720
31%
1223
March16th to endNight
40%
768
20%
2112
11%
768
48%
768
31%
1343
April1st to 15thNight
42%
718
23%
1925
12%
718
49%
718
35%
1170
April16th to endNight
48%
673
24%
1748
14%
673
54%
673
35%
1083
May1st to 15thNight
50%
494
19%
1485
12%
494
55%
494
27%
938
May16th to endNight
64%
513
17%
1538
13%
513
66%
513
30%
966
June1st to 15thNight
66%
495
15%
1485
13%
495
67%
495
26%
985
June16th to endNight
72%
495
14%
1485
13%
495
73%
495
29%
962
July1st to 15thNight
68%
465
12%
1395
9%
465
68%
465
24%
955
July16th to endNight
73%
522
11%
1469
10%
489
75%
489
26%
994
August1st to 15thNight
70%
494
15%
1474
13%
491
70%
491
24%
1011
August16th to endNight
66%
630
15%
1680
12%
630
66%
630
25%
1184
September1st to 15thNight
69%
660
20%
1807
18%
660
69%
660
26%
1225
September16th to endNight
54%
657
15%
1815
13%
657
56%
657
23%
1279
October1st to 15thNight
54%
660
30%
1936
27%
660
60%
660
34%
1144
October16th to endNight
55%
704
33%
2112
27%
704
66%
704
38%
1162
November1st to 15thNight
53%
700
31%
2101
23%
700
63%
700
38%
1168
November16th to endNight
45%
720
26%
2325
19%
720
56%
720
30%
1355
December1st to 15thNight
45%
720
24%
2340
19%
720
55%
720
26%
1444
December16th to endNight
38%
768
23%
2496
17%
768
46%
768
22%
1595

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%7%42%
46116
Night
11%5%2442445%7%45%
45804
TransparencyDay
38%7%11%19%17%5%
45817
Night
36%6%11%18%18%7%
45607
SeeingDay
14%418%24%24%14%
5129
Night
14%5%22%33%21%2
15402

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%6%24324445%45%
1611
16th to endDay
15%5%235%24345%47%
1728
February1st to 15thDay
15%6%25%323345%46%
1630
16th to endDay
15%5%2442433448%
1628
March1st to 15thDay
13%423423247%49%
1980
16th to endDay
14%425%5%23446%45%
2111
April1st to 15thDay
10%323425%45%7%49%
2023
16th to endDay
9%425%42446%8%48%
2201
May1st to 15thDay
9%5%25%5%36%5%5%7%43%
2136
16th to endDay
8%6%25%6%36%5%7%8%38%
2223
June1st to 15thDay
9%4245%36%5%7%10%39%
2145
16th to endDay
5%3245%36%8%8%10%40%
2145
July1st to 15thDay
8%5%26%7%5%7%6%7%10%31%
2145
16th to endDay
6%437%6%37%8%9%12%29%
2283
August1st to 15thDay
10%5%26%6%36%7%7%11%31%
2145
16th to endDay
12%6%26%6%37%5%8%11%29%
2157
September1st to 15thDay
9%5%25%5%35%5%6%9%40%
1821
16th to endDay
19%6%25%435%447%37%
1815
October1st to 15thDay
17%313423335%51%
1692
16th to endDay
10%42431233459%
1760
November1st to 15thDay
13%423223235%55%
1757
16th to endDay
13%5%245%13336%49%
1632
December1st to 15thDay
15%7%345%24445%42%
1620
16th to endDay
19%6%24423445%41%
1728
January1st to 15thNight
13%6%25%424435%47%
2327
16th to endNight
16%6%2442334446%
2496
February1st to 15thNight
16%414424346%46%
2220
16th to endNight
13%5%25%423346%49%
1845
March1st to 15thNight
11%424424447%48%
1980
16th to endNight
12%42442435%6%47%
2112
April1st to 15thNight
10%423415%447%51%
1925
16th to endNight
9%3245%3445%7%50%
1748
May1st to 15thNight
8%5%246%3446%9%42%
1484
16th to endNight
7%4245%25%5%7%10%44%
1538
June1st to 15thNight
10%4246%46%6%8%11%35%
1485
16th to endNight
44246%35%5%8%10%41%
1485
July1st to 15thNight
7%6%36%5%46%8%8%10%33%
1485
16th to endNight
44347%36%8%10%12%34%
1577
August1st to 15thNight
7%5%26%5%37%7%8%12%33%
1485
16th to endNight
10%5%25%7%46%5%7%12%33%
1680
September1st to 15thNight
8%5%26%5%45%5%6%9%40%
1807
16th to endNight
16%6%36%5%34446%37%
1815
October1st to 15thNight
16%413322345%51%
1936
16th to endNight
9%5%23312346%56%
2112
November1st to 15thNight
12%413213236%57%
2101
16th to endNight
14%5%23323346%49%
2325
December1st to 15thNight
15%5%23424346%46%
2340
16th to endNight
17%6%34423446%42%
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%49%16%21%6%
1612
16th to endDay
39%37%17%23%8%
1728
February1st to 15thDay
39%37%19%23%6%
1632
16th to endDay
39%36%20%23%6%
1628
March1st to 15thDay
35%48%21%20%9%
1980
16th to endDay
40%6%9%19%19%4
2112
April1st to 15thDay
33%5%11%20%22%7%
2023
16th to endDay
32%5%11%20%21%7%
2201
May1st to 15thDay
38%7%14%20%17%1
2136
16th to endDay
40%8%14%22%12%1
2227
June1st to 15thDay
37%8%17%25%10%
2145
16th to endDay
32%11%18%23%11%2
2145
July1st to 15thDay
41%12%16%18%7%3
2006
16th to endDay
39%14%20%17%6%1
2128
August1st to 15thDay
42%11%16%18%10%
2132
16th to endDay
44%13%15%17%8%1
2157
September1st to 15thDay
38%10%13%17%16%4
1821
16th to endDay
47%5%9%16%15%4
1815
October1st to 15thDay
36%38%21%23%7%
1692
16th to endDay
29%46%18%29%12%
1760
November1st to 15thDay
31%36%18%27%11%
1757
16th to endDay
35%49%17%22%9%
1632
December1st to 15thDay
43%49%17%17%6%
1620
16th to endDay
43%48%19%16%7%
1728
January1st to 15thNight
38%5%9%14%25%7%
2327
16th to endNight
40%45%18%21%10%
2496
February1st to 15thNight
38%37%18%20%10%
2229
16th to endNight
36%48%20%21%9%
1845
March1st to 15thNight
35%5%10%18%21%9%
1980
16th to endNight
35%6%11%19%19%6%
2112
April1st to 15thNight
31%5%10%19%23%8%
1925
16th to endNight
32%6%11%19%21%9%
1748
May1st to 15thNight
37%8%14%19%17%1
1485
16th to endNight
33%10%16%25%12%1
1540
June1st to 15thNight
39%9%18%23%9%
1485
16th to endNight
33%12%19%22%10%2
1485
July1st to 15thNight
38%13%19%16%7%3
1395
16th to endNight
34%15%23%16%8%1
1469
August1st to 15thNight
39%12%20%17%9%1
1474
16th to endNight
42%10%19%18%8%
1680
September1st to 15thNight
38%10%13%18%13%5%
1807
16th to endNight
47%6%11%15%13%4
1815
October1st to 15thNight
34%39%19%24%8%
1936
16th to endNight
28%47%20%25%14%
2112
November1st to 15thNight
29%36%15%28%15%
2101
16th to endNight
35%47%15%23%13%
2325
December1st to 15thNight
38%5%9%18%19%8%
2340
16th to endNight
43%49%17%16%8%
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%13%36%22%10%2
90
16th to endDay
14%22%39%18%31
96
February1st to 15thDay
16%21%50%11%1
90
16th to endDay
14%13%34%31%5%
129
March1st to 15thDay
13%10%30%31%12%
270
16th to endDay
12%8%32%25%17%2
288
April1st to 15thDay
14%10%22%24%22%5%
270
16th to endDay
12%322%27%22%12%
266
May1st to 15thDay
11%5%22%28%22%10%
228
16th to endDay
12%211%19%28%25%
267
June1st to 15thDay
11%110%22%29%24%
255
16th to endDay
6%10%24%30%27%
255
July1st to 15thDay
10%7%29%28%23%
245
16th to endDay
8%420%40%25%
270
August1st to 15thDay
15%15%22%30%25%
253
16th to endDay
15%7%15%29%32%
268
September1st to 15thDay
14%16%20%36%21%
255
16th to endDay
24%112%25%22%12%
254
October1st to 15thDay
21%114%27%25%7%
255
16th to endDay
9%320%25%27%12%
272
November1st to 15thDay
20%5%18%26%23%6%
265
16th to endDay
8%8%23%31%20%6%
102
December1st to 15thDay
14%7%36%25%14%1
90
16th to endDay
23%14%28%19%12%1
96
January1st to 15thNight
16%11%31%30%8%
720
16th to endNight
19%10%33%32%3
768
February1st to 15thNight
19%11%31%32%4
704
16th to endNight
16%9%36%33%4
631
March1st to 15thNight
14%8%35%32%8%
720
16th to endNight
13%7%33%32%12%
768
April1st to 15thNight
12%11%31%32%12%
718
16th to endNight
11%6%27%37%15%
673
May1st to 15thNight
11%427%40%15%1
495
16th to endNight
10%115%33%36%3
515
June1st to 15thNight
11%111%39%29%5%
495
16th to endNight
6%18%38%38%7%
495
July1st to 15thNight
10%16%39%36%6%
465
16th to endNight
7%16%35%43%6%
522
August1st to 15thNight
10%15%29%45%8%
494
16th to endNight
13%15%27%43%7%
630
September1st to 15thNight
8%17%28%46%6%
660
16th to endNight
20%211%31%29%3
657
October1st to 15thNight
19%118%29%26%3
660
16th to endNight
12%5%21%31%25%2
704
November1st to 15thNight
14%5%22%36%18%3
700
16th to endNight
16%7%27%28%18%1
720
December1st to 15thNight
18%6%22%36%14%1
720
16th to endNight
21%7%26%33%9%1
768
Page generated at 2017-04-30 20:40:06. Version ac04

Copyright 2017 A. Danko


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