Cat Island (South)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cat Island (South) clear sky chart from 2005-11-05 to 2017-09-18.

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
0%
3256
0%
32947
0%
3007
0%
3007
26%
32119

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
0%
177
0%
1475
0%
166
0%
166
23%
1447
January16th to endNight
0%
177
0%
1372
0%
158
0%
158
29%
1443
February1st to 15thNight
0%
186
0%
1188
0%
147
0%
147
31%
1282
February16th to endNight
0%
138
0%
907
0%
116
0%
116
40%
1045
March1st to 15thNight
0%
194
0%
1253
0%
169
0%
169
29%
1306
March16th to endNight
0%
168
0%
1193
0%
147
0%
147
36%
1288
April1st to 15thNight
0%
97
0%
977
0%
89
0%
89
41%
1109
April16th to endNight
0%
138
0%
1026
0%
113
0%
113
38%
1140
May1st to 15thNight
0%
87
0%
997
0%
81
0%
81
40%
1135
May16th to endNight
0%
208
0%
1507
0%
208
0%
208
18%
1460
June1st to 15thNight
0%
143
0%
1620
0%
143
0%
143
15%
1464
June16th to endNight
0%
85
0%
1541
0%
85
0%
85
24%
1338
July1st to 15thNight
0%
59
0%
1455
0%
59
0%
59
24%
1244
July16th to endNight
0%
53
0%
1373
0%
47
0%
47
29%
1226
August1st to 15thNight
0%
46
0%
1307
0%
46
0%
46
33%
1170
August16th to endNight
0%
72
0%
1541
0%
71
0%
71
28%
1343
September1st to 15thNight
0%
84
0%
1501
0%
81
0%
81
25%
1290
September16th to endNight
0%
63
0%
1558
0%
62
0%
62
19%
1356
October1st to 15thNight
0%
141
0%
1638
0%
141
0%
141
14%
1491
October16th to endNight
0%
219
0%
1668
0%
210
0%
210
14%
1629
November1st to 15thNight
0%
190
0%
1498
0%
181
0%
181
19%
1521
November16th to endNight
0%
194
0%
1468
0%
174
0%
174
22%
1479
December1st to 15thNight
0%
168
0%
1430
0%
157
0%
157
26%
1413
December16th to endNight
0%
169
0%
1454
0%
156
0%
156
24%
1500

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
TransparencyDay
40%12%20%19%7%
47668
Night
39%11%19%20%8%
46827
SeeingDay
8%18%24%38%18%
6883
Night
8%18%24%39%16%
17235

By Month

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%9%18%23%8%
1791
16th to endDay
36%8%15%26%12%
1920
February1st to 15thDay
33%7%14%24%17%2
1753
16th to endDay
29%7%17%27%15%2
1608
March1st to 15thDay
37%9%17%17%16%1
1980
16th to endDay
33%8%17%28%9%2
2156
April1st to 15thDay
26%8%20%33%9%1
2152
16th to endDay
32%9%18%24%13%1
2160
May1st to 15thDay
30%8%18%28%11%2
2152
16th to endDay
54%11%17%12%3
2248
June1st to 15thDay
57%14%18%8%1
2160
16th to endDay
44%18%25%11%
2160
July1st to 15thDay
38%19%26%14%
2032
16th to endDay
36%19%28%15%
2132
August1st to 15thDay
31%14%30%21%1
2148
16th to endDay
39%17%27%14%
2292
September1st to 15thDay
42%16%29%10%
2160
16th to endDay
46%20%22%10%
1859
October1st to 15thDay
53%15%18%9%3
1768
16th to endDay
51%10%14%12%7%2
1760
November1st to 15thDay
49%8%11%17%11%
1757
16th to endDay
41%9%14%18%13%2
1800
December1st to 15thDay
36%9%16%24%12%
1800
16th to endDay
39%6%14%24%14%
1920
January1st to 15thNight
42%8%17%21%8%1
2148
16th to endNight
34%9%15%25%14%1
2304
February1st to 15thNight
33%7%14%24%16%2
2111
16th to endNight
26%7%15%31%16%2
1860
March1st to 15thNight
37%8%16%21%14%
1980
16th to endNight
32%7%18%26%13%2
2067
April1st to 15thNight
27%8%18%32%11%1
1796
16th to endNight
31%7%18%27%13%1
1800
May1st to 15thNight
29%7%17%27%15%2
1800
16th to endNight
55%8%16%14%5%
1870
June1st to 15thNight
53%15%21%8%1
1800
16th to endNight
38%17%29%13%
1800
July1st to 15thNight
37%17%30%14%
1700
16th to endNight
34%14%28%21%1
1773
August1st to 15thNight
30%13%29%24%2
1787
16th to endNight
36%13%30%18%
1910
September1st to 15thNight
36%16%30%15%1
1800
16th to endNight
40%19%25%13%1
1826
October1st to 15thNight
54%13%19%9%2
1858
16th to endNight
54%11%12%11%7%1
2112
November1st to 15thNight
48%9%12%17%10%
2101
16th to endNight
44%8%15%18%11%1
2160
December1st to 15thNight
39%8%17%23%9%
2160
16th to endNight
41%7%14%22%13%
2304

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
12%312%36%28%5%
270
16th to endDay
5%417%38%29%4
288
February1st to 15thDay
4319%33%34%5%
266
16th to endDay
6%315%40%30%2
239
March1st to 15thDay
6%116%42%31%2
270
16th to endDay
8%214%37%31%4
288
April1st to 15thDay
5%17%38%42%4
270
16th to endDay
7%113%40%33%2
270
May1st to 15thDay
4434%44%11%
288
16th to endDay
16%16%9%45%21%
331
June1st to 15thDay
15%149%46%21%
315
16th to endDay
7%28%45%36%
315
July1st to 15thDay
329%51%32%
305
16th to endDay
4110%46%37%
326
August1st to 15thDay
328%47%37%
313
16th to endDay
6%212%46%31%
332
September1st to 15thDay
7%119%31%47%
315
16th to endDay
7%37%28%53%
262
October1st to 15thDay
18%1314%39%22%
255
16th to endDay
23%110%23%27%13%
272
November1st to 15thDay
9%113%29%35%10%
265
16th to endDay
9%117%40%27%3
270
December1st to 15thDay
8%10%32%38%10%
270
16th to endDay
7%211%27%44%6%
288
January1st to 15thNight
9%212%33%36%4
720
16th to endNight
5%115%40%34%1
768
February1st to 15thNight
6%316%32%38%1
704
16th to endNight
6%213%38%37%3
631
March1st to 15thNight
8%117%36%34%1
720
16th to endNight
5%114%40%32%4
768
April1st to 15thNight
417%40%42%3
718
16th to endNight
6%12%40%37%2
720
May1st to 15thNight
5%15%33%47%7%
720
16th to endNight
16%38%21%37%13%
749
June1st to 15thNight
12%15%15%44%20%
720
16th to endNight
8%28%47%32%
720
July1st to 15thNight
5%210%47%33%
680
16th to endNight
429%43%39%
753
August1st to 15thNight
429%42%41%
719
16th to endNight
5%311%45%33%
764
September1st to 15thNight
7%128%30%48%
720
16th to endNight
6%27%34%48%
669
October1st to 15thNight
14%15%14%41%22%
660
16th to endNight
19%29%18%30%19%
704
November1st to 15thNight
12%212%28%37%6%
700
16th to endNight
9%214%33%35%4
720
December1st to 15thNight
8%311%29%40%5%
720
16th to endNight
9%210%29%42%5%
768
Page generated at 2017-09-19 07:32:28. Version ac04

Copyright 2017 A. Danko


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