Greenville Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Greenville Recreation Area clear sky chart from 2005-11-05 to 2017-03-25.

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%
15235
23%
45294
14%
15188
50%
15188
29%
27719

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%
900
24%
2437
8%
895
35%
895
25%
1563
January16th to endNight
24%
960
25%
2496
8%
960
36%
960
29%
1604
February1st to 15thNight
21%
809
21%
2217
5%
806
31%
806
24%
1438
February16th to endNight
20%
631
23%
1893
6%
631
34%
631
23%
1178
March1st to 15thNight
25%
644
19%
2084
9%
644
34%
644
20%
1372
March16th to endNight
30%
558
16%
1979
12%
558
38%
558
19%
1324
April1st to 15thNight
30%
494
26%
1647
12%
494
50%
494
28%
940
April16th to endNight
36%
495
21%
1650
13%
495
48%
495
25%
1007
May1st to 15thNight
39%
495
18%
1600
12%
494
48%
494
25%
1011
May16th to endNight
46%
515
18%
1370
12%
513
50%
513
28%
926
June1st to 15thNight
63%
495
24%
1320
17%
495
67%
495
40%
785
June16th to endNight
66%
495
24%
1320
16%
495
71%
495
43%
765
July1st to 15thNight
68%
465
19%
1240
16%
465
70%
465
38%
760
July16th to endNight
76%
522
21%
1428
20%
489
78%
489
41%
798
August1st to 15thNight
78%
494
24%
1563
27%
491
80%
491
43%
808
August16th to endNight
71%
525
24%
1750
27%
525
73%
525
34%
978
September1st to 15thNight
64%
495
28%
1650
29%
495
69%
495
31%
947
September16th to endNight
57%
606
30%
1764
22%
606
64%
606
36%
1022
October1st to 15thNight
52%
660
31%
1974
23%
660
59%
660
36%
1103
October16th to endNight
41%
704
30%
2112
18%
704
52%
704
32%
1231
November1st to 15thNight
42%
700
31%
2259
20%
700
56%
700
36%
1197
November16th to endNight
32%
720
25%
2340
17%
720
43%
720
24%
1436
December1st to 15thNight
30%
893
19%
2513
9%
893
39%
893
22%
1712
December16th to endNight
25%
960
21%
2688
7%
960
36%
960
23%
1814

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%25%43445%7%43%
45663
Night
13%5%24423446%48%
45482
TransparencyDay
38%6%11%23%15%2
45353
Night
36%5%11%24%18%3
45297
SeeingDay
14%7%24%25%20%8%
5018
Night
16%9%27%27%16%2
15235

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
19%5%2432233447%
1498
16th to endDay
14%6%25%422436%47%
1728
February1st to 15thDay
15%8%26%423345%42%
1645
16th to endDay
13%8%36%424446%39%
1580
March1st to 15thDay
20%7%25%423236%41%
1887
16th to endDay
18%8%36%5%34446%35%
2109
April1st to 15thDay
13%5%345%23336%47%
1971
16th to endDay
17%6%25%5%24446%40%
1980
May1st to 15thDay
16%5%37%5%3446%7%34%
2020
16th to endDay
12%5%26%5%36%5%6%8%38%
2388
June1st to 15thDay
6%415%6%45%5%6%9%42%
2310
16th to endDay
4223446%7%7%10%46%
2310
July1st to 15thDay
8%5%25%5%45%6%7%10%37%
2310
16th to endDay
33146%47%6%7%11%42%
2323
August1st to 15thDay
7%3245%46%6%8%10%40%
2057
16th to endDay
8%4245%36%6%6%8%43%
2100
September1st to 15thDay
11%425%33445%8%45%
1980
16th to endDay
12%41442435%8%47%
1854
October1st to 15thDay
12%5%14423337%50%
1653
16th to endDay
15%413312346%54%
1760
November1st to 15thDay
12%425%313345%53%
1598
16th to endDay
20%7%2321333446%
1620
December1st to 15thDay
19%6%26%413445%39%
1446
16th to endDay
21%6%24413446%40%
1536
January1st to 15thNight
19%424313445%46%
2437
16th to endNight
14%5%34313346%48%
2496
February1st to 15thNight
15%7%35%323345%45%
2208
16th to endNight
13%6%25%414346%45%
1893
March1st to 15thNight
18%6%25%5%2434343%
2084
16th to endNight
17%7%35%5%34345%39%
1979
April1st to 15thNight
10%4243235%5%6%50%
1647
16th to endNight
15%414424446%44%
1650
May1st to 15thNight
16%5%2442346%7%42%
1600
16th to endNight
9%5%35%5%35%45%7%42%
1370
June1st to 15thNight
6%214425%5%6%9%52%
1320
16th to endNight
43134245%6%10%52%
1320
July1st to 15thNight
6%3135%245%7%9%49%
1320
16th to endNight
5%3133146%7%10%51%
1535
August1st to 15thNight
42123245%7%11%53%
1573
16th to endNight
6%424425%46%8%50%
1750
September1st to 15thNight
8%425%425%45%7%50%
1650
16th to endNight
10%425%323336%54%
1764
October1st to 15thNight
9%4145%23346%56%
1974
16th to endNight
15%5%1422223454%
2112
November1st to 15thNight
10%413313346%57%
2259
16th to endNight
18%6%2432223448%
2340
December1st to 15thNight
20%6%34423335%40%
2513
16th to endNight
20%7%25%313335%42%
2688

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%39%27%15%3
1499
16th to endDay
38%413%27%13%2
1728
February1st to 15thDay
43%411%24%14%1
1647
16th to endDay
43%5%12%22%13%2
1580
March1st to 15thDay
45%49%21%14%4
1887
16th to endDay
50%5%12%20%10%
2111
April1st to 15thDay
38%49%23%20%2
1971
16th to endDay
44%5%9%23%14%1
1980
May1st to 15thDay
47%8%10%19%13%
2020
16th to endDay
42%9%14%19%10%3
2392
June1st to 15thDay
34%9%12%26%15%1
2310
16th to endDay
28%9%15%26%16%3
2310
July1st to 15thDay
38%9%12%23%12%4
2161
16th to endDay
31%9%17%28%11%1
2167
August1st to 15thDay
34%8%13%24%17%1
2043
16th to endDay
34%7%14%21%16%5%
2100
September1st to 15thDay
34%6%11%24%18%4
1980
16th to endDay
35%5%8%24%23%3
1854
October1st to 15thDay
34%5%8%23%22%5%
1653
16th to endDay
31%36%30%22%4
1760
November1st to 15thDay
33%48%23%21%8%
1598
16th to endDay
42%27%25%20%1
1620
December1st to 15thDay
46%410%23%13%2
1446
16th to endDay
44%5%12%21%12%2
1536
January1st to 15thNight
39%49%25%19%2
2437
16th to endNight
36%411%27%17%2
2496
February1st to 15thNight
41%310%24%17%2
2217
16th to endNight
38%413%22%17%2
1893
March1st to 15thNight
46%39%19%16%4
2084
16th to endNight
47%5%10%23%12%1
1979
April1st to 15thNight
32%5%10%26%20%4
1647
16th to endNight
38%5%8%25%18%3
1650
May1st to 15thNight
39%6%14%22%14%2
1601
16th to endNight
39%8%13%20%14%3
1372
June1st to 15thNight
26%8%13%31%18%2
1320
16th to endNight
24%8%13%27%20%5%
1320
July1st to 15thNight
30%7%15%26%13%6%
1240
16th to endNight
23%8%17%31%16%1
1428
August1st to 15thNight
21%7%16%30%21%3
1563
16th to endNight
29%6%12%25%18%6%
1750
September1st to 15thNight
31%7%7%27%18%6%
1650
16th to endNight
31%49%22%27%4
1764
October1st to 15thNight
30%49%22%27%6%
1974
16th to endNight
33%37%25%22%6%
2112
November1st to 15thNight
27%49%25%25%7%
2259
16th to endNight
41%27%24%21%2
2340
December1st to 15thNight
45%5%10%20%15%2
2513
16th to endNight
44%410%22%14%3
2688

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
35%16%35%11%1
90
16th to endDay
20%22%44%9%2
96
February1st to 15thDay
23%22%37%13%3
90
16th to endDay
22%23%40%11%2
81
March1st to 15thDay
41%13%31%11%3
90
16th to endDay
20%18%31%23%5%
144
April1st to 15thDay
19%13%34%22%9%
210
16th to endDay
16%8%31%26%13%3
210
May1st to 15thDay
19%9%28%26%11%3
228
16th to endDay
16%5%30%26%14%6%
432
June1st to 15thDay
9%328%27%21%10%
420
16th to endDay
5%327%37%20%7%
420
July1st to 15thDay
11%219%33%25%8%
400
16th to endDay
5%111%29%34%16%
445
August1st to 15thDay
9%10%27%36%15%
330
16th to endDay
14%111%22%33%16%
268
September1st to 15thDay
8%312%25%33%15%
255
16th to endDay
14%6%15%21%29%12%
254
October1st to 15thDay
20%6%26%35%7%3
93
16th to endDay
14%7%31%34%12%
96
November1st to 15thDay
11%12%30%27%14%4
90
16th to endDay
46%11%18%12%11%
90
December1st to 15thDay
17%20%34%16%5%5%
90
16th to endDay
33%18%37%8%2
96
January1st to 15thNight
24%18%32%20%4
900
16th to endNight
19%15%38%25%2
960
February1st to 15thNight
20%16%38%21%2
809
16th to endNight
20%17%38%19%3
631
March1st to 15thNight
22%13%35%26%1
644
16th to endNight
21%9%33%26%8%
558
April1st to 15thNight
13%14%39%25%6%
494
16th to endNight
16%11%30%29%11%
495
May1st to 15thNight
19%5%29%30%13%1
495
16th to endNight
13%327%29%21%4
515
June1st to 15thNight
7%318%37%29%4
495
16th to endNight
4119%38%30%3
495
July1st to 15thNight
8%113%38%35%3
465
16th to endNight
6%19%29%43%9%
522
August1st to 15thNight
418%31%46%7%
494
16th to endNight
6%111%32%41%6%
525
September1st to 15thNight
10%212%29%39%6%
495
16th to endNight
12%420%24%31%7%
606
October1st to 15thNight
12%6%21%28%25%4
660
16th to endNight
19%9%28%27%14%
704
November1st to 15thNight
12%10%32%28%15%1
700
16th to endNight
24%10%28%26%9%
720
December1st to 15thNight
25%12%27%26%6%
893
16th to endNight
27%11%32%24%4
960
Page generated at 2017-03-26 12:16:37. Version ac04

Copyright 2017 A. Danko


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