Dolan Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dolan Lake clear sky chart from 2005-11-05 to 2017-09-24.

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
46%
15796
22%
46924
16%
15750
52%
15750
28%
29535

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
26%
900
19%
2506
8%
895
36%
895
23%
1699
January16th to endNight
26%
960
18%
2552
8%
960
34%
960
24%
1778
February1st to 15thNight
25%
728
17%
2136
7%
725
32%
725
19%
1490
February16th to endNight
24%
631
18%
1893
7%
631
33%
631
21%
1283
March1st to 15thNight
29%
720
17%
2160
9%
720
36%
720
21%
1472
March16th to endNight
35%
608
16%
2005
12%
608
41%
608
20%
1334
April1st to 15thNight
39%
539
22%
1797
13%
539
51%
539
27%
1084
April16th to endNight
45%
540
20%
1800
17%
540
53%
540
25%
1127
May1st to 15thNight
45%
540
18%
1628
12%
539
51%
539
25%
1074
May16th to endNight
60%
562
20%
1581
15%
561
62%
561
30%
1025
June1st to 15thNight
69%
540
22%
1440
17%
540
71%
540
42%
850
June16th to endNight
70%
540
24%
1440
18%
540
73%
540
44%
812
July1st to 15thNight
73%
510
19%
1360
16%
510
73%
510
39%
814
July16th to endNight
75%
564
25%
1417
21%
531
77%
531
44%
822
August1st to 15thNight
80%
539
23%
1766
28%
536
80%
536
40%
927
August16th to endNight
76%
573
26%
1910
32%
573
77%
573
37%
1035
September1st to 15thNight
67%
546
27%
1806
31%
546
69%
546
33%
1027
September16th to endNight
65%
693
31%
1914
25%
693
68%
693
38%
1129
October1st to 15thNight
58%
660
31%
1881
24%
660
64%
660
38%
1096
October16th to endNight
42%
704
27%
2189
20%
704
52%
704
31%
1312
November1st to 15thNight
48%
700
30%
2276
24%
700
58%
700
34%
1262
November16th to endNight
37%
720
24%
2340
18%
720
46%
720
27%
1426
December1st to 15thNight
32%
819
16%
2439
11%
819
38%
819
20%
1724
December16th to endNight
26%
960
17%
2688
7%
960
36%
960
20%
1933

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%6%25%5%345%5%7%41%
48021
Night
13%6%25%424446%45%
47100
TransparencyDay
40%6%12%23%14%2
47699
Night
39%411%23%17%3
46926
SeeingDay
14%420%24%23%12%
5826
Night
16%6%24%31%18%2
15797

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
19%8%48%43343435%
1432
16th to endDay
12%10%46%5%2345%5%38%
1671
February1st to 15thDay
15%9%5%6%5%23345%38%
1725
16th to endDay
12%8%47%5%36%445%35%
1580
March1st to 15thDay
19%8%35%5%33435%38%
1800
16th to endDay
16%7%46%5%35%45%7%31%
2227
April1st to 15thDay
12%6%24335%35%7%45%
2151
16th to endDay
17%6%25%5%2445%6%38%
2160
May1st to 15thDay
19%5%35%4345%5%7%34%
2322
16th to endDay
10%5%26%5%36%6%6%7%38%
2530
June1st to 15thDay
8%425%425%5%6%8%45%
2520
16th to endDay
6%325%5%26%5%6%9%45%
2520
July1st to 15thDay
10%3245%35%6%6%10%40%
2520
16th to endDay
42145%46%7%7%11%43%
2655
August1st to 15thDay
7%3245%35%6%5%10%44%
2179
16th to endDay
7%4245%25%6%7%9%45%
2292
September1st to 15thDay
10%6%25%5%245%5%7%44%
2142
16th to endDay
10%425%42435%6%50%
1905
October1st to 15thDay
13%5%14423346%50%
1748
16th to endDay
14%3235%13446%50%
1683
November1st to 15thDay
10%5%145%3435%5%50%
1582
16th to endDay
19%7%25%5%2223444%
1620
December1st to 15thDay
20%9%36%423345%35%
1521
16th to endDay
17%11%45%423436%35%
1536
January1st to 15thNight
18%7%26%423445%39%
2506
16th to endNight
15%8%36%5%2445%5%38%
2552
February1st to 15thNight
16%9%46%5%24445%36%
2127
16th to endNight
13%8%37%5%33445%39%
1893
March1st to 15thNight
16%8%36%434335%39%
2160
16th to endNight
17%6%35%5%24446%38%
2005
April1st to 15thNight
12%6%244335%46%47%
1797
16th to endNight
17%5%2442435%6%42%
1800
May1st to 15thNight
14%6%25%42435%6%43%
1628
16th to endNight
6%425%5%45%6%5%9%42%
1580
June1st to 15thNight
6%3134245%6%8%52%
1440
16th to endNight
5%22332446%11%51%
1440
July1st to 15thNight
7%313415%5%5%9%50%
1440
16th to endNight
6%2144246%6%9%52%
1513
August1st to 15thNight
5%31432445%10%55%
1776
16th to endNight
4415%42445%9%53%
1910
September1st to 15thNight
9%425%423446%52%
1806
16th to endNight
10%424423347%53%
1914
October1st to 15thNight
9%425%323346%54%
1881
16th to endNight
17%5%2441223450%
2189
November1st to 15thNight
11%42332235%5%53%
2276
16th to endNight
17%5%25%313335%47%
2340
December1st to 15thNight
22%7%36%424346%34%
2439
16th to endNight
21%10%35%424335%35%
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
52%311%20%11%
1433
16th to endDay
46%5%12%26%8%
1671
February1st to 15thDay
47%411%23%10%1
1727
16th to endDay
49%412%20%12%1
1580
March1st to 15thDay
47%5%9%22%12%1
1800
16th to endDay
50%5%15%20%7%
2228
April1st to 15thDay
38%5%11%26%17%1
2151
16th to endDay
44%5%11%24%11%1
2160
May1st to 15thDay
47%7%11%22%10%
2322
16th to endDay
40%9%14%19%12%3
2534
June1st to 15thDay
32%7%13%25%18%2
2520
16th to endDay
33%7%13%21%19%4
2520
July1st to 15thDay
36%8%12%22%14%5%
2371
16th to endDay
29%8%17%27%14%2
2488
August1st to 15thDay
33%8%12%26%16%2
2165
16th to endDay
31%8%14%22%17%5%
2292
September1st to 15thDay
38%49%23%18%5%
2142
16th to endDay
34%5%8%25%23%3
1905
October1st to 15thDay
34%48%27%20%5%
1748
16th to endDay
35%38%29%20%3
1683
November1st to 15thDay
35%49%23%19%8%
1582
16th to endDay
44%38%27%13%2
1620
December1st to 15thDay
50%413%19%10%
1521
16th to endDay
50%411%22%9%1
1536
January1st to 15thNight
46%310%21%16%1
2506
16th to endNight
46%412%22%12%1
2552
February1st to 15thNight
49%49%23%11%1
2136
16th to endNight
46%412%22%12%
1893
March1st to 15thNight
47%49%19%14%3
2160
16th to endNight
46%5%14%21%11%1
2005
April1st to 15thNight
37%5%11%22%19%3
1797
16th to endNight
41%49%24%15%3
1800
May1st to 15thNight
42%6%11%24%14%1
1629
16th to endNight
36%9%12%21%16%4
1582
June1st to 15thNight
27%6%14%27%22%2
1440
16th to endNight
25%6%16%23%23%6%
1440
July1st to 15thNight
29%6%14%26%16%6%
1360
16th to endNight
25%6%13%33%17%2
1417
August1st to 15thNight
24%7%15%25%23%3
1766
16th to endNight
27%6%12%25%21%5%
1910
September1st to 15thNight
32%48%26%21%6%
1806
16th to endNight
31%37%23%25%7%
1914
October1st to 15thNight
31%39%22%26%6%
1881
16th to endNight
38%25%29%17%6%
2189
November1st to 15thNight
31%39%23%25%7%
2276
16th to endNight
40%39%25%19%2
2340
December1st to 15thNight
51%410%20%12%1
2439
16th to endNight
52%311%20%10%1
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
34%10%33%12%8%1
90
16th to endDay
13%22%40%16%6%
96
February1st to 15thDay
18%17%44%16%2
90
16th to endDay
23%14%29%25%6%
81
March1st to 15thDay
28%11%38%15%5%
90
16th to endDay
20%9%30%27%11%
234
April1st to 15thDay
16%8%31%25%16%1
270
16th to endDay
20%5%26%26%16%5%
270
May1st to 15thDay
21%8%26%24%12%6%
288
16th to endDay
16%225%24%21%10%
430
June1st to 15thDay
10%217%25%29%14%
495
16th to endDay
7%222%33%25%8%
495
July1st to 15thDay
13%214%29%25%15%
475
16th to endDay
5%8%22%38%24%
515
August1st to 15thDay
12%8%21%31%26%
323
16th to endDay
10%16%26%36%18%
332
September1st to 15thDay
12%29%20%33%20%
315
16th to endDay
13%210%21%31%20%
287
October1st to 15thDay
12%121%28%22%14%
188
16th to endDay
14%328%32%20%1
96
November1st to 15thDay
28%24%22%32%10%
90
16th to endDay
38%6%22%20%11%1
90
December1st to 15thDay
15%10%40%23%6%4
90
16th to endDay
26%13%45%12%2
96
January1st to 15thNight
21%13%35%25%4
900
16th to endNight
19%10%38%28%3
960
February1st to 15thNight
21%13%34%27%2
728
16th to endNight
17%12%39%28%2
631
March1st to 15thNight
19%10%35%30%3
720
16th to endNight
20%6%30%30%10%1
608
April1st to 15thNight
15%8%33%30%11%
539
16th to endNight
19%5%24%34%14%1
540
May1st to 15thNight
17%5%23%37%15%
540
16th to endNight
8%219%38%28%3
563
June1st to 15thNight
7%215%42%29%2
540
16th to endNight
6%213%42%32%2
540
July1st to 15thNight
10%8%35%40%3
510
16th to endNight
7%18%30%42%9%
564
August1st to 15thNight
6%5%34%42%10%
539
16th to endNight
5%6%35%44%6%
573
September1st to 15thNight
12%110%29%37%8%
546
16th to endNight
13%213%27%34%8%
693
October1st to 15thNight
12%319%31%26%6%
660
16th to endNight
20%5%28%29%14%1
704
November1st to 15thNight
12%7%26%35%16%1
700
16th to endNight
21%7%29%27%12%
720
December1st to 15thNight
26%8%28%27%8%1
819
16th to endNight
26%8%33%26%4
960
Page generated at 2017-09-25 08:02:26. Version ac04

Copyright 2017 A. Danko


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