Elliott Island road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Elliott Island road clear sky chart from 2005-11-05 to 2018-01-12.

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
42%
15749
20%
48380
12%
15712
51%
15712
26%
30431

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
27%
763
21%
2611
9%
761
42%
761
20%
1601
January16th to endNight
24%
768
21%
2496
9%
768
40%
768
22%
1574
February1st to 15thNight
25%
701
20%
2258
10%
701
39%
701
23%
1405
February16th to endNight
23%
631
25%
1893
8%
631
44%
631
25%
1175
March1st to 15thNight
30%
720
20%
2057
10%
720
42%
720
26%
1319
March16th to endNight
33%
768
21%
2052
11%
768
42%
768
27%
1372
April1st to 15thNight
32%
718
18%
1796
6%
718
39%
718
32%
1194
April16th to endNight
43%
720
19%
1800
8%
720
46%
720
32%
1192
May1st to 15thNight
41%
597
17%
1677
9%
597
47%
597
26%
1135
May16th to endNight
60%
374
17%
1497
17%
374
63%
374
22%
894
June1st to 15thNight
61%
360
17%
1440
19%
360
66%
360
24%
852
June16th to endNight
61%
360
14%
1440
14%
360
65%
360
22%
856
July1st to 15thNight
67%
340
13%
1360
17%
340
67%
340
21%
821
July16th to endNight
69%
499
16%
1531
15%
467
71%
467
29%
906
August1st to 15thNight
67%
589
16%
1659
11%
586
68%
586
30%
1063
August16th to endNight
67%
764
18%
1910
11%
764
68%
764
34%
1260
September1st to 15thNight
61%
720
24%
1800
15%
720
64%
720
36%
1172
September16th to endNight
58%
717
22%
1945
18%
717
61%
717
29%
1279
October1st to 15thNight
48%
720
22%
2160
21%
720
53%
720
25%
1392
October16th to endNight
41%
768
29%
2304
20%
768
55%
768
30%
1365
November1st to 15thNight
40%
760
21%
2457
14%
760
51%
760
26%
1497
November16th to endNight
37%
780
25%
2595
17%
780
50%
780
24%
1558
December1st to 15thNight
29%
780
17%
2730
9%
780
41%
780
18%
1747
December16th to endNight
25%
832
22%
2912
11%
832
41%
832
20%
1802

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%2442445%8%44%
48950
Night
13%5%2442445%7%43%
48562
Cloud CoverDay
12%42442445%8%45%
48960
Night
14%5%2442445%7%43%
48566
TransparencyDay
36%6%13%24%16%2
48650
Night
39%5%12%23%16%3
48380
SeeingDay
16%6%23%26%19%8%
6139
Night
16%7%26%31%15%1
15755

By Month

Percentage Cloud Cover NE (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
14%6%25%42435%8%41%
1568
16th to endDay
17%6%345%24348%41%
1728
February1st to 15thDay
14%6%25%425%448%40%
1601
16th to endDay
13%6%25%4245%5%6%42%
1580
March1st to 15thDay
15%5%15%32335%6%47%
1891
16th to endDay
17%5%24324436%44%
2172
April1st to 15thDay
12%5%23334447%48%
2152
16th to endDay
13%5%23423447%47%
2160
May1st to 15thDay
14%5%2442345%9%44%
2282
16th to endDay
12%4243245%5%9%47%
2618
June1st to 15thDay
10%314425%5%6%9%45%
2520
16th to endDay
7%3234345%7%10%46%
2520
July1st to 15thDay
8%425%425%5%6%9%44%
2520
16th to endDay
5%2245%35%7%8%12%41%
2528
August1st to 15thDay
8%5%26%425%6%6%8%43%
2277
16th to endDay
8%3246%445%6%9%44%
2292
September1st to 15thDay
11%5%2342446%8%46%
2160
16th to endDay
14%7%36%5%24346%40%
2013
October1st to 15thDay
14%6%15%5%2435%5%45%
1800
16th to endDay
13%414323247%50%
1920
November1st to 15thDay
16%414423446%46%
1731
16th to endDay
14%425%423337%49%
1693
December1st to 15thDay
14%6%35%41445%7%42%
1560
16th to endDay
18%6%25%424446%40%
1664
January1st to 15thNight
15%5%2442345%9%41%
2611
16th to endNight
16%7%34424345%43%
2496
February1st to 15thNight
14%6%25%423348%43%
2257
16th to endNight
14%6%24323347%46%
1893
March1st to 15thNight
15%5%25%424446%44%
2045
16th to endNight
16%7%35%313346%42%
2052
April1st to 15thNight
12%5%25%5%24446%45%
1796
16th to endNight
15%5%24324446%45%
1800
May1st to 15thNight
14%5%34435%5%6%9%37%
1677
16th to endNight
11%5%25%43446%8%44%
1495
June1st to 15thNight
10%3245%25%5%5%11%42%
1440
16th to endNight
7%5%35%6%35%6%5%10%40%
1440
July1st to 15thNight
8%435%5%35%5%7%9%40%
1440
16th to endNight
5%435%5%35%6%9%10%41%
1637
August1st to 15thNight
7%5%25%5%35%5%7%8%42%
1670
16th to endNight
8%425%425%5%6%9%43%
1910
September1st to 15thNight
12%5%2441335%8%48%
1800
16th to endNight
14%6%24424348%43%
1945
October1st to 15thNight
16%6%35%423435%44%
2160
16th to endNight
16%413323346%50%
2304
November1st to 15thNight
15%5%25%41335%5%47%
2457
16th to endNight
14%5%24423447%46%
2595
December1st to 15thNight
16%6%35%5%2436%6%39%
2730
16th to endNight
17%6%25%413447%42%
2912

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
14%5%25%41436%8%40%
1568
16th to endDay
17%6%245%34347%41%
1728
February1st to 15thDay
14%6%25%325%5%5%7%40%
1601
16th to endDay
14%6%2333446%7%42%
1580
March1st to 15thDay
15%5%2432335%5%47%
1902
16th to endDay
17%5%24424345%44%
2171
April1st to 15thDay
11%414324447%48%
2152
16th to endDay
13%5%24322447%47%
2160
May1st to 15thDay
14%42342346%8%44%
2282
16th to endDay
12%31342446%9%48%
2618
June1st to 15thDay
10%313435%46%10%46%
2520
16th to endDay
7%3234345%7%10%47%
2520
July1st to 15thDay
8%4244245%5%10%45%
2520
16th to endDay
5%2145%37%6%8%11%42%
2528
August1st to 15thDay
9%426%4245%6%8%43%
2277
16th to endDay
9%3146%3445%9%45%
2292
September1st to 15thDay
11%5%1442345%8%47%
2160
16th to endDay
14%7%35%43445%5%41%
2013
October1st to 15thDay
14%5%26%43345%5%45%
1800
16th to endDay
14%423423347%50%
1920
November1st to 15thDay
15%4235%2345%6%46%
1731
16th to endDay
13%4245%13347%49%
1693
December1st to 15thDay
14%6%26%42435%7%42%
1560
16th to endDay
18%6%245%2435%6%40%
1664
January1st to 15thNight
15%5%2442445%9%39%
2611
16th to endNight
17%6%25%42435%5%42%
2496
February1st to 15thNight
15%6%3442345%6%44%
2250
16th to endNight
14%6%24323348%45%
1893
March1st to 15thNight
16%6%14333447%43%
2057
16th to endNight
17%7%24423246%43%
2052
April1st to 15thNight
12%5%26%4235%47%44%
1796
16th to endNight
16%5%1342436%6%45%
1800
May1st to 15thNight
15%5%25%425%46%10%37%
1676
16th to endNight
11%5%15%5%2445%8%44%
1495
June1st to 15thNight
10%3245%25%5%6%10%43%
1440
16th to endNight
8%436%5%36%5%6%9%41%
1440
July1st to 15thNight
8%5%26%435%5%7%8%41%
1440
16th to endNight
6%335%436%6%7%10%41%
1637
August1st to 15thNight
7%426%6%35%5%7%8%42%
1670
16th to endNight
9%5%25%4345%6%8%43%
1910
September1st to 15thNight
12%5%2443335%7%48%
1800
16th to endNight
15%5%24433448%42%
1945
October1st to 15thNight
17%6%24423435%44%
2160
16th to endNight
15%413413346%49%
2304
November1st to 15thNight
15%5%24423346%47%
2457
16th to endNight
14%5%24423448%44%
2595
December1st to 15thNight
17%6%26%42445%6%38%
2730
16th to endNight
17%6%25%413346%42%
2912

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%413%22%13%4
1569
16th to endDay
43%410%23%15%2
1728
February1st to 15thDay
41%5%10%23%15%2
1604
16th to endDay
40%5%11%24%15%2
1580
March1st to 15thDay
37%5%13%24%15%2
1902
16th to endDay
41%5%9%23%16%3
2172
April1st to 15thDay
34%6%10%26%17%4
2152
16th to endDay
36%5%10%19%20%6%
2160
May1st to 15thDay
36%8%14%22%16%1
2282
16th to endDay
32%8%16%27%13%1
2622
June1st to 15thDay
32%8%15%27%14%1
2520
16th to endDay
30%8%16%23%17%2
2520
July1st to 15thDay
33%8%16%23%14%2
2371
16th to endDay
29%11%17%24%15%2
2371
August1st to 15thDay
35%8%14%24%15%1
2264
16th to endDay
35%8%14%19%18%3
2292
September1st to 15thDay
34%8%13%21%18%3
2160
16th to endDay
43%5%8%18%21%1
2013
October1st to 15thDay
40%5%9%26%15%3
1800
16th to endDay
35%38%28%20%3
1920
November1st to 15thDay
38%312%24%17%3
1731
16th to endDay
37%310%26%18%3
1693
December1st to 15thDay
41%5%14%22%13%2
1560
16th to endDay
44%411%25%12%1
1664
January1st to 15thNight
40%412%22%15%4
2611
16th to endNight
43%310%25%14%2
2496
February1st to 15thNight
39%5%9%25%17%2
2258
16th to endNight
38%49%25%20%2
1893
March1st to 15thNight
40%411%26%14%2
2057
16th to endNight
43%39%21%17%3
2052
April1st to 15thNight
38%5%11%20%19%4
1796
16th to endNight
38%5%9%20%19%5%
1800
May1st to 15thNight
40%8%14%20%14%1
1677
16th to endNight
37%8%15%21%14%1
1497
June1st to 15thNight
35%9%13%25%14%1
1440
16th to endNight
37%8%15%18%17%1
1440
July1st to 15thNight
38%8%16%20%12%2
1360
16th to endNight
32%9%17%25%14%
1531
August1st to 15thNight
36%7%16%21%17%
1659
16th to endNight
35%7%14%20%19%2
1910
September1st to 15thNight
35%6%14%22%17%3
1800
16th to endNight
40%5%8%21%20%3
1945
October1st to 15thNight
42%48%24%16%3
2160
16th to endNight
35%39%26%21%3
2304
November1st to 15thNight
39%410%23%17%5%
2457
16th to endNight
38%48%25%18%4
2595
December1st to 15thNight
45%412%22%12%2
2730
16th to endNight
42%412%23%13%2
2912

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
14%23%35%16%10%
90
16th to endDay
22%19%33%20%3
96
February1st to 15thDay
25%13%38%18%3
118
16th to endDay
15%15%38%28%2
239
March1st to 15thDay
18%11%29%30%8%1
270
16th to endDay
18%6%40%24%7%3
288
April1st to 15thDay
14%11%30%27%14%1
270
16th to endDay
18%5%24%29%16%4
270
May1st to 15thDay
22%10%29%18%13%5%
288
16th to endDay
18%219%24%25%9%
331
June1st to 15thDay
14%221%24%22%13%
315
16th to endDay
10%121%35%22%7%
315
July1st to 15thDay
12%114%34%23%12%
305
16th to endDay
7%19%30%35%15%
326
August1st to 15thDay
10%13%29%33%12%
313
16th to endDay
9%15%30%35%17%
332
September1st to 15thDay
12%220%25%21%17%
315
16th to endDay
24%415%24%19%11%
314
October1st to 15thDay
19%420%27%20%9%
315
16th to endDay
12%9%30%24%17%5%
336
November1st to 15thDay
20%6%26%26%17%3
284
16th to endDay
15%14%28%24%11%5%
223
December1st to 15thDay
18%18%28%16%15%1
90
16th to endDay
28%14%35%16%41
96
January1st to 15thNight
17%14%34%27%6%
765
16th to endNight
20%11%38%26%2
768
February1st to 15thNight
17%14%35%29%2
704
16th to endNight
17%14%40%23%3
631
March1st to 15thNight
20%11%32%28%6%
720
16th to endNight
19%6%34%29%7%1
768
April1st to 15thNight
13%7%41%31%5%
718
16th to endNight
17%5%28%35%11%
720
May1st to 15thNight
16%7%30%33%11%1
597
16th to endNight
12%317%42%22%2
375
June1st to 15thNight
9%218%45%23%1
360
16th to endNight
8%115%45%27%1
360
July1st to 15thNight
11%10%43%31%2
340
16th to endNight
6%110%40%37%3
499
August1st to 15thNight
10%18%40%35%3
589
16th to endNight
10%19%38%33%5%
764
September1st to 15thNight
15%112%34%32%4
720
16th to endNight
18%214%34%26%4
717
October1st to 15thNight
18%420%32%21%3
720
16th to endNight
19%8%27%25%17%1
768
November1st to 15thNight
17%6%28%29%14%3
760
16th to endNight
16%13%26%29%12%1
780
December1st to 15thNight
20%11%31%23%11%1
780
16th to endNight
20%12%36%27%3
832
Page generated at 2018-01-12 22:01:33. Version ac04

Copyright 2018 A. Danko


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