Charlie Elliott WLC
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Charlie Elliott WLC clear sky chart from 2005-11-05 to 2017-08-12.

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
48%
15429
24%
46555
16%
15387
57%
15387
28%
28445

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
28%
719
24%
2327
10%
716
45%
716
20%
1423
January16th to endNight
27%
768
25%
2460
12%
768
43%
768
22%
1526
February1st to 15thNight
32%
704
27%
2111
11%
701
48%
701
25%
1279
February16th to endNight
26%
631
26%
1893
10%
631
43%
631
24%
1160
March1st to 15thNight
32%
720
26%
2043
13%
720
44%
720
27%
1260
March16th to endNight
39%
768
23%
2112
12%
768
48%
768
30%
1284
April1st to 15thNight
42%
677
26%
1935
16%
677
52%
677
35%
1110
April16th to endNight
51%
540
27%
1687
17%
540
61%
540
32%
958
May1st to 15thNight
51%
540
22%
1620
13%
540
58%
540
31%
973
May16th to endNight
61%
561
22%
1682
16%
561
65%
561
34%
1001
June1st to 15thNight
70%
540
17%
1620
15%
540
71%
540
32%
1007
June16th to endNight
76%
540
18%
1620
16%
540
77%
540
35%
948
July1st to 15thNight
72%
510
12%
1530
10%
510
73%
510
29%
989
July16th to endNight
75%
564
16%
1595
13%
531
76%
531
29%
1023
August1st to 15thNight
69%
527
18%
1583
18%
524
70%
524
25%
1059
August16th to endNight
63%
531
16%
1756
17%
531
64%
531
20%
1202
September1st to 15thNight
64%
660
20%
1815
18%
660
66%
660
28%
1223
September16th to endNight
57%
657
23%
1815
16%
657
62%
657
29%
1181
October1st to 15thNight
52%
660
32%
1835
24%
660
60%
660
35%
1101
October16th to endNight
53%
704
34%
2112
26%
704
65%
704
36%
1166
November1st to 15thNight
50%
700
32%
2228
26%
700
62%
700
37%
1176
November16th to endNight
41%
720
28%
2340
18%
720
56%
720
29%
1326
December1st to 15thNight
37%
720
25%
2340
15%
720
50%
720
24%
1430
December16th to endNight
32%
768
22%
2496
14%
768
42%
768
19%
1640

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%245%35%5%5%7%42%
47410
Night
11%42442445%7%45%
46755
TransparencyDay
39%5%11%20%18%5%
47111
Night
36%410%20%20%7%
46558
SeeingDay
16%6%17%22%23%12%
5286
Night
14%8%20%29%22%4
15432

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
16%7%34323336%45%
1611
16th to endDay
18%424314446%44%
1761
February1st to 15thDay
15%5%244235%45%44%
1750
16th to endDay
17%6%23424445%44%
1580
March1st to 15thDay
15%4345%23236%46%
1917
16th to endDay
15%5%2442345%6%44%
2111
April1st to 15thDay
12%425%42435%6%47%
2024
16th to endDay
9%424435%45%6%50%
2271
May1st to 15thDay
9%6%246%2446%6%45%
2331
16th to endDay
9%425%5%36%6%6%8%41%
2431
June1st to 15thDay
9%425%7%47%7%7%10%34%
2340
16th to endDay
5%3135%37%7%7%10%42%
2340
July1st to 15thDay
8%5%36%7%47%7%8%10%30%
2340
16th to endDay
6%435%7%48%9%8%11%29%
2465
August1st to 15thDay
8%5%36%8%5%7%6%8%10%28%
2277
16th to endDay
13%6%37%7%46%5%7%9%27%
2081
September1st to 15thDay
12%5%25%5%46%5%7%7%35%
1815
16th to endDay
17%6%24433446%41%
1815
October1st to 15thDay
14%413322336%53%
1793
16th to endDay
11%412313345%58%
1760
November1st to 15thDay
12%413323435%55%
1629
16th to endDay
14%5%2442443449%
1620
December1st to 15thDay
15%7%25%434335%43%
1620
16th to endDay
24%6%26%423345%36%
1728
January1st to 15thNight
16%6%24423345%46%
2327
16th to endNight
17%5%25%423435%44%
2460
February1st to 15thNight
14%5%14424336%47%
2103
16th to endNight
15%42443344448%
1893
March1st to 15thNight
12%4245%33346%49%
2043
16th to endNight
12%41332445%7%50%
2112
April1st to 15thNight
13%312213448%51%
1935
16th to endNight
7%42443345%8%49%
1687
May1st to 15thNight
9%4245%45%35%7%46%
1619
16th to endNight
7%325%5%35%5%6%9%46%
1682
June1st to 15thNight
7%425%426%5%7%12%40%
1620
16th to endNight
42245%36%6%9%12%41%
1620
July1st to 15thNight
8%424436%6%9%12%36%
1620
16th to endNight
5%3145%47%8%9%13%36%
1703
August1st to 15thNight
5%5%25%6%37%7%7%14%33%
1594
16th to endNight
12%425%7%46%6%6%9%33%
1756
September1st to 15thNight
8%5%27%6%35%6%7%10%36%
1815
16th to endNight
13%5%25%4335%47%43%
1815
October1st to 15thNight
13%5%25%323345%52%
1835
16th to endNight
10%31332433459%
2112
November1st to 15thNight
10%323313245%59%
2228
16th to endNight
13%424323336%52%
2340
December1st to 15thNight
14%6%23423346%45%
2340
16th to endNight
20%7%25%424346%39%
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
42%38%15%25%5%
1612
16th to endDay
40%36%19%22%8%
1761
February1st to 15thDay
40%36%20%22%5%
1752
16th to endDay
41%35%21%20%7%
1580
March1st to 15thDay
39%29%20%20%8%
1917
16th to endDay
39%5%10%21%18%4
2112
April1st to 15thDay
36%39%21%21%7%
2024
16th to endDay
33%48%22%24%5%
2271
May1st to 15thDay
37%5%12%20%19%4
2331
16th to endDay
37%6%12%26%14%2
2435
June1st to 15thDay
41%6%16%24%8%1
2340
16th to endDay
31%8%18%23%16%2
2340
July1st to 15thDay
41%9%20%18%7%2
2201
16th to endDay
41%10%16%22%8%1
2310
August1st to 15thDay
46%8%16%20%7%
2264
16th to endDay
50%8%15%15%10%
2081
September1st to 15thDay
43%8%12%17%15%2
1815
16th to endDay
42%49%20%17%4
1815
October1st to 15thDay
32%39%21%25%7%
1793
16th to endDay
29%26%17%33%11%
1760
November1st to 15thDay
32%26%16%30%11%
1629
16th to endDay
37%35%18%27%8%
1620
December1st to 15thDay
43%38%21%16%7%
1620
16th to endDay
49%37%19%13%7%
1728
January1st to 15thNight
40%35%19%24%6%
2327
16th to endNight
41%25%18%21%10%
2460
February1st to 15thNight
38%2420%21%11%
2112
16th to endNight
38%35%20%23%8%
1893
March1st to 15thNight
36%38%20%21%9%
2043
16th to endNight
33%410%22%22%6%
2112
April1st to 15thNight
31%39%25%22%8%
1935
16th to endNight
30%5%10%21%22%9%
1687
May1st to 15thNight
35%413%20%21%4
1620
16th to endNight
33%5%15%26%15%3
1684
June1st to 15thNight
34%7%18%27%11%
1620
16th to endNight
30%7%21%23%14%3
1620
July1st to 15thNight
34%10%24%19%7%3
1530
16th to endNight
33%11%23%19%9%2
1595
August1st to 15thNight
39%10%16%22%10%1
1583
16th to endNight
45%9%16%16%12%1
1756
September1st to 15thNight
39%8%15%17%14%4
1815
16th to endNight
40%5%11%18%18%5%
1815
October1st to 15thNight
34%38%18%25%9%
1835
16th to endNight
29%3417%30%15%
2112
November1st to 15thNight
28%26%17%30%15%
2228
16th to endNight
34%26%16%27%12%
2340
December1st to 15thNight
39%37%21%19%8%
2340
16th to endNight
47%27%17%18%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%13%40%13%8%1
90
16th to endDay
16%34%33%8%7%
96
February1st to 15thDay
24%17%40%15%2
90
16th to endDay
28%7%48%14%1
81
March1st to 15thDay
19%14%28%28%9%
207
16th to endDay
17%10%31%24%15%
288
April1st to 15thDay
17%13%22%21%20%4
270
16th to endDay
13%6%22%28%23%5%
270
May1st to 15thDay
16%8%28%17%15%13%
288
16th to endDay
16%416%22%25%15%
331
June1st to 15thDay
11%110%21%30%23%
315
16th to endDay
7%113%24%27%24%
315
July1st to 15thDay
8%7%26%32%24%
305
16th to endDay
5%16%18%39%28%
326
August1st to 15thDay
16%1426%32%18%
297
16th to endDay
18%1322%32%22%
268
September1st to 15thDay
14%28%21%31%21%
255
16th to endDay
22%212%25%28%8%
254
October1st to 15thDay
24%219%23%22%7%
255
16th to endDay
13%6%16%28%27%6%
272
November1st to 15thDay
26%8%19%25%18%1
137
16th to endDay
14%11%23%31%15%4
90
December1st to 15thDay
27%13%30%20%8%
90
16th to endDay
42%10%21%18%5%1
96
January1st to 15thNight
23%18%24%25%8%
720
16th to endNight
21%14%30%27%5%
768
February1st to 15thNight
21%14%27%31%5%
704
16th to endNight
17%18%32%27%3
631
March1st to 15thNight
16%13%32%28%8%
720
16th to endNight
16%11%27%29%13%
768
April1st to 15thNight
16%10%28%27%16%
677
16th to endNight
11%7%22%34%22%1
540
May1st to 15thNight
11%325%30%24%3
540
16th to endNight
8%215%32%33%7%
563
June1st to 15thNight
9%9%33%35%10%
540
16th to endNight
5%26%33%39%13%
540
July1st to 15thNight
9%15%24%43%15%
510
16th to endNight
5%16%25%48%12%
564
August1st to 15thNight
9%1425%45%12%
527
16th to endNight
15%15%24%40%12%
531
September1st to 15thNight
10%18%25%44%10%
660
16th to endNight
17%113%31%31%4
657
October1st to 15thNight
15%321%27%25%5%
660
16th to endNight
11%8%20%30%24%3
704
November1st to 15thNight
11%9%23%32%22%1
700
16th to endNight
15%12%25%30%15%1
720
December1st to 15thNight
18%13%24%28%12%1
720
16th to endNight
24%12%24%29%9%
768
Page generated at 2017-08-13 14:16:40. Version ac04

Copyright 2017 A. Danko


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