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 2017-09-14.

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%
15272
20%
46852
12%
15235
51%
15235
26%
29532

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%
718
21%
2455
9%
716
42%
716
20%
1534
January16th to endNight
24%
768
21%
2496
9%
768
41%
768
22%
1574
February1st to 15thNight
25%
701
20%
2258
10%
701
40%
701
23%
1405
February16th to endNight
23%
631
25%
1893
8%
631
44%
631
25%
1175
March1st to 15thNight
30%
720
21%
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
19%
1796
6%
718
39%
718
32%
1194
April16th to endNight
44%
720
19%
1800
8%
720
47%
720
32%
1192
May1st to 15thNight
42%
597
17%
1677
9%
597
48%
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
60%
360
14%
1440
14%
360
64%
360
22%
856
July1st to 15thNight
66%
340
13%
1360
17%
340
67%
340
21%
821
July16th to endNight
66%
499
16%
1531
15%
467
69%
467
29%
906
August1st to 15thNight
66%
589
16%
1659
11%
586
67%
586
30%
1063
August16th to endNight
68%
764
18%
1910
11%
764
69%
764
34%
1260
September1st to 15thNight
61%
716
24%
1790
15%
716
63%
716
35%
1167
September16th to endNight
57%
657
20%
1783
16%
657
59%
657
28%
1182
October1st to 15thNight
49%
660
23%
1980
22%
660
54%
660
26%
1271
October16th to endNight
41%
704
27%
2112
18%
704
53%
704
29%
1267
November1st to 15thNight
40%
700
22%
2263
15%
700
51%
700
27%
1363
November16th to endNight
36%
720
23%
2395
15%
720
48%
720
23%
1464
December1st to 15thNight
28%
720
18%
2520
10%
720
40%
720
19%
1604
December16th to endNight
25%
768
22%
2688
10%
768
41%
768
20%
1662

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%
47856
Night
14%5%2442445%7%43%
47034
Cloud CoverDay
12%42442445%8%45%
47866
Night
14%5%2442445%7%43%
47038
TransparencyDay
36%6%13%23%16%2
47556
Night
39%5%12%23%16%3
46852
SeeingDay
16%6%23%26%19%8%
5780
Night
16%7%26%32%15%1
15278

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%7%41%
1480
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%
2146
16th to endDay
15%7%35%5%34346%39%
1845
October1st to 15thDay
15%6%15%5%2435%5%45%
1650
16th to endDay
14%5%14323247%49%
1760
November1st to 15thDay
16%413423446%47%
1595
16th to endDay
15%425%424337%47%
1563
December1st to 15thDay
13%6%35%41445%7%42%
1440
16th to endDay
19%6%25%424346%40%
1536
January1st to 15thNight
15%5%34433448%41%
2455
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%
1790
16th to endNight
15%6%24424348%42%
1783
October1st to 15thNight
15%5%35%424435%45%
1980
16th to endNight
16%413323346%48%
2112
November1st to 15thNight
14%5%25%41335%449%
2263
16th to endNight
14%6%34423447%44%
2395
December1st to 15thNight
16%6%35%5%2436%6%39%
2520
16th to endNight
18%6%24313347%42%
2688

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%6%36%5%2436%7%40%
1480
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%
2146
16th to endDay
15%7%35%43445%5%39%
1845
October1st to 15thDay
14%6%16%42344446%
1650
16th to endDay
14%423423347%48%
1760
November1st to 15thDay
15%4225%2335%6%47%
1595
16th to endDay
14%4245%13347%46%
1563
December1st to 15thDay
13%7%36%42435%7%42%
1440
16th to endDay
19%6%245%2335%6%40%
1536
January1st to 15thNight
15%5%3442445%8%40%
2455
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%24423347%48%
1790
16th to endNight
16%6%24434448%41%
1783
October1st to 15thNight
16%6%34423435%44%
1980
16th to endNight
16%423413346%47%
2112
November1st to 15thNight
15%5%24423346%48%
2263
16th to endNight
14%5%24423448%43%
2395
December1st to 15thNight
16%6%25%42445%6%39%
2520
16th to endNight
18%6%25%413346%43%
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
42%5%12%21%14%3
1481
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
2146
16th to endDay
44%5%9%17%21%1
1845
October1st to 15thDay
40%5%9%26%15%3
1650
16th to endDay
36%39%27%20%3
1760
November1st to 15thDay
37%312%24%18%3
1595
16th to endDay
38%311%25%16%3
1563
December1st to 15thDay
40%5%14%22%13%3
1440
16th to endDay
44%411%24%13%1
1536
January1st to 15thNight
41%412%21%16%3
2455
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
1790
16th to endNight
40%6%9%19%20%3
1783
October1st to 15thNight
41%48%25%16%3
1980
16th to endNight
36%310%25%20%3
2112
November1st to 15thNight
38%310%23%18%5%
2263
16th to endNight
39%5%9%25%16%4
2395
December1st to 15thNight
44%412%21%12%3
2520
16th to endNight
42%412%23%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
16%23%38%16%5%
68
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%20%18%
310
16th to endDay
27%312%24%19%12%
254
October1st to 15thDay
17%421%27%20%8%
255
16th to endDay
12%9%30%26%16%3
272
November1st to 15thDay
20%6%25%24%18%4
238
16th to endDay
18%14%24%25%12%6%
183
December1st to 15thDay
16%18%30%16%16%1
60
16th to endDay
32%14%34%12%41
64
January1st to 15thNight
17%13%35%27%5%
720
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
716
16th to endNight
18%213%35%26%3
657
October1st to 15thNight
18%419%33%21%2
660
16th to endNight
19%8%27%26%16%
704
November1st to 15thNight
17%7%29%27%15%3
700
16th to endNight
17%12%26%28%12%1
720
December1st to 15thNight
20%11%32%23%10%1
720
16th to endNight
21%11%35%27%3
768
Page generated at 2017-09-15 10:29:57. Version ac04

Copyright 2017 A. Danko


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