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 2018-02-22.

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%
16190
24%
48893
16%
16148
57%
16148
28%
29808

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%
779
24%
2522
10%
776
45%
776
19%
1548
January16th to endNight
27%
832
26%
2665
13%
832
43%
832
22%
1641
February1st to 15thNight
31%
764
26%
2291
11%
761
46%
761
24%
1413
February16th to endNight
27%
659
26%
1977
10%
659
43%
659
24%
1214
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%
539
18%
1618
17%
536
70%
536
25%
1082
August16th to endNight
64%
580
18%
1917
19%
580
65%
580
21%
1294
September1st to 15thNight
64%
720
19%
1980
17%
720
65%
720
29%
1317
September16th to endNight
60%
717
26%
1980
19%
717
65%
717
31%
1255
October1st to 15thNight
52%
720
31%
2002
23%
720
60%
720
36%
1191
October16th to endNight
53%
768
36%
2304
27%
768
66%
768
37%
1261
November1st to 15thNight
51%
760
31%
2419
25%
760
62%
760
37%
1289
November16th to endNight
42%
780
29%
2535
19%
780
57%
780
30%
1422
December1st to 15thNight
37%
780
25%
2535
14%
780
51%
780
24%
1546
December16th to endNight
31%
832
22%
2704
14%
832
42%
832
19%
1782

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%
49352
Night
11%42442445%7%46%
49093
TransparencyDay
39%5%11%20%18%5%
49053
Night
36%410%20%20%7%
48896
SeeingDay
16%6%18%23%23%11%
5954
Night
14%8%20%28%22%4
16193

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%24323336%45%
1746
16th to endDay
17%424324446%45%
1908
February1st to 15thDay
17%5%244235%45%42%
1900
16th to endDay
17%6%23424445%43%
1643
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%7%8%10%28%
2328
16th to endDay
13%6%36%7%46%6%7%9%28%
2271
September1st to 15thDay
12%5%25%5%46%5%7%7%37%
1980
16th to endDay
16%6%24333446%44%
1980
October1st to 15thDay
14%413323336%53%
1956
16th to endDay
10%412313345%59%
1920
November1st to 15thDay
12%413413445%54%
1768
16th to endDay
13%5%24424335%50%
1755
December1st to 15thDay
16%7%25%433335%43%
1755
16th to endDay
24%7%26%423345%36%
1872
January1st to 15thNight
15%7%24423345%46%
2522
16th to endNight
16%5%25%423435%45%
2665
February1st to 15thNight
16%5%24423336%46%
2283
16th to endNight
15%42443345%5%47%
1977
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%38%7%7%14%33%
1629
16th to endNight
11%4247%46%6%6%9%34%
1917
September1st to 15thNight
8%426%6%35%6%7%9%38%
1980
16th to endNight
12%5%25%4335%47%45%
1980
October1st to 15thNight
12%5%15%323345%53%
2002
16th to endNight
9%31332333459%
2304
November1st to 15thNight
10%323313245%58%
2419
16th to endNight
12%424323336%52%
2535
December1st to 15thNight
15%6%23423345%46%
2535
16th to endNight
20%7%35%424346%38%
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
41%38%16%25%5%
1747
16th to endDay
39%26%19%22%9%
1908
February1st to 15thDay
42%36%20%21%5%
1902
16th to endDay
41%45%21%20%6%
1643
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
45%8%17%20%7%
2315
16th to endDay
49%7%15%15%10%
2271
September1st to 15thDay
42%7%12%17%17%2
1980
16th to endDay
40%49%21%19%4
1980
October1st to 15thDay
32%39%22%25%7%
1956
16th to endDay
28%25%17%33%12%
1920
November1st to 15thDay
32%27%16%29%10%
1768
16th to endDay
36%36%17%27%8%
1755
December1st to 15thDay
43%28%20%17%7%
1755
16th to endDay
50%37%19%13%6%
1872
January1st to 15thNight
40%35%19%24%6%
2522
16th to endNight
41%2418%22%10%
2665
February1st to 15thNight
40%25%20%21%10%
2292
16th to endNight
38%36%20%23%8%
1977
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%
1618
16th to endNight
44%8%16%17%12%1
1917
September1st to 15thNight
38%8%14%16%16%4
1980
16th to endNight
37%5%11%20%19%5%
1980
October1st to 15thNight
33%38%20%25%8%
2002
16th to endNight
28%3416%31%15%
2304
November1st to 15thNight
29%27%18%28%14%
2419
16th to endNight
33%26%17%26%12%
2535
December1st to 15thNight
39%38%21%19%7%
2535
16th to endNight
47%27%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
24%14%38%14%7%
135
16th to endDay
19%29%29%13%8%
144
February1st to 15thDay
30%14%39%13%2
135
16th to endDay
29%9%43%18%1
100
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
15%1427%33%17%
313
16th to endDay
17%16%22%31%21%
332
September1st to 15thDay
14%311%22%30%17%
315
16th to endDay
18%211%25%30%11%
314
October1st to 15thDay
23%119%23%23%8%
315
16th to endDay
13%8%18%28%25%6%
336
November1st to 15thDay
23%5%20%27%19%2
186
16th to endDay
13%8%24%33%14%5%
135
December1st to 15thDay
31%11%27%22%7%
135
16th to endDay
38%13%25%18%3
144
January1st to 15thNight
22%18%23%26%7%
780
16th to endNight
21%14%29%26%6%
832
February1st to 15thNight
22%14%26%31%5%
764
16th to endNight
17%17%33%27%3
659
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%46%12%
539
16th to endNight
15%15%25%41%11%
580
September1st to 15thNight
10%19%25%43%10%
720
16th to endNight
15%112%29%34%6%
717
October1st to 15thNight
15%221%27%26%6%
720
16th to endNight
11%8%21%29%25%3
768
November1st to 15thNight
11%8%22%31%23%1
760
16th to endNight
14%12%24%30%15%1
780
December1st to 15thNight
19%12%24%28%12%1
780
16th to endNight
24%12%25%29%8%
832
Page generated at 2018-02-23 11:21:34. Version ac04

Copyright 2018 A. Danko


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