Miller Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Miller Lake clear sky chart from 2005-11-05 to

2017-09-12
.

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
29%
15193
10%
46700
7%
15152
33%
15152
13%
35331

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
8%
899
1%
2621
0%
895
9%
895
3%
2412
January16th to endNight
15%
837
5%
2565
3%
837
17%
837
4%
2283
February1st to 15thNight
14%
702
5%
2287
2%
701
17%
701
6%
1956
February16th to endNight
23%
631
8%
1973
4%
631
28%
631
9%
1584
March1st to 15thNight
23%
720
12%
2031
7%
720
27%
720
14%
1533
March16th to endNight
33%
768
19%
2112
9%
768
40%
768
20%
1461
April1st to 15thNight
27%
650
15%
1794
6%
650
33%
650
20%
1248
April16th to endNight
31%
540
18%
1620
7%
540
40%
540
18%
1098
May1st to 15thNight
41%
531
14%
1611
11%
531
45%
531
18%
1095
May16th to endNight
41%
374
13%
1491
12%
374
50%
374
18%
883
June1st to 15thNight
41%
360
13%
1260
12%
360
49%
360
20%
792
June16th to endNight
50%
360
12%
1260
11%
360
55%
360
22%
767
July1st to 15thNight
62%
340
17%
1190
20%
340
65%
340
32%
633
July16th to endNight
51%
529
15%
1476
14%
496
59%
496
29%
913
August1st to 15thNight
56%
539
17%
1609
14%
536
61%
536
28%
962
August16th to endNight
56%
573
18%
1719
11%
573
61%
573
28%
1046
September1st to 15thNight
50%
695
14%
1833
9%
695
52%
695
27%
1238
September16th to endNight
46%
657
17%
1815
11%
657
49%
657
25%
1222
October1st to 15thNight
31%
660
12%
1961
9%
660
36%
660
15%
1458
October16th to endNight
19%
704
7%
2168
3%
704
24%
704
8%
1789
November1st to 15thNight
24%
700
11%
2360
11%
700
28%
700
10%
1836
November16th to endNight
17%
720
4%
2520
3%
720
19%
720
5%
2141
December1st to 15thNight
9%
744
1%
2544
0%
744
10%
744
2%
2340
December16th to endNight
7%
960
2%
2880
0%
960
9%
960
2%
2641

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
15%9%47%5%3445%6%33%
47959
Night
16%11%5%8%6%3445%6%28%
46868
Cloud CoverDay
15%9%47%5%3445%6%33%
47969
Night
16%11%5%8%6%3445%6%28%
46872
TransparencyDay
50%6%12%19%9%
47645
Night
57%6%11%15%8%
46700
SeeingDay
17%13%22%27%14%4
5809
Night
19%22%21%22%11%2
15197

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
19%20%9%13%9%444238%
1316
16th to endDay
15%19%9%13%9%45%4339%
1657
February1st to 15thDay
13%19%7%13%10%35%335%15%
1575
16th to endDay
14%16%7%8%8%46%44420%
1500
March1st to 15thDay
12%10%48%6%45%45%6%31%
1918
16th to endDay
13%7%37%6%35%5%5%5%35%
2112
April1st to 15thDay
20%9%35%5%24346%33%
2165
16th to endDay
17%8%2432335%7%40%
2340
May1st to 15thDay
17%7%25%42445%7%39%
2337
16th to endDay
11%42442445%7%47%
2621
June1st to 15thDay
12%5%35%5%345%5%8%40%
2700
16th to endDay
10%5%25%435%5%6%8%40%
2700
July1st to 15thDay
8%42443445%8%49%
2700
16th to endDay
8%325%4345%6%9%47%
2584
August1st to 15thDay
10%42442345%7%48%
2340
16th to endDay
12%6%26%4245%5%8%41%
2483
September1st to 15thDay
13%5%26%435%447%40%
2033
16th to endDay
17%6%35%3246%48%38%
1815
October1st to 15thDay
21%9%36%5%34445%31%
1669
16th to endDay
30%11%48%7%34345%16%
1702
November1st to 15thDay
19%12%48%6%35%5%5%6%21%
1495
16th to endDay
22%19%6%8%8%3443412%
1440
December1st to 15thDay
20%23%7%12%10%35%3337%
1413
16th to endDay
22%24%8%13%6%432337%
1344
January1st to 15thNight
20%19%8%12%10%344347%
2621
16th to endNight
15%18%9%12%10%4434412%
2565
February1st to 15thNight
12%18%8%12%9%34445%15%
2285
16th to endNight
14%12%7%10%7%36%5%45%21%
1973
March1st to 15thNight
15%12%46%6%3445%5%30%
2019
16th to endNight
14%7%37%5%2445%5%38%
2112
April1st to 15thNight
21%8%34424345%36%
1794
16th to endNight
18%8%24415%35%7%37%
1620
May1st to 15thNight
15%8%35%5%35%35%6%36%
1611
16th to endNight
11%426%5%35%45%6%43%
1489
June1st to 15thNight
13%6%346%26%449%39%
1260
16th to endNight
9%5%24445%6%6%8%41%
1260
July1st to 15thNight
7%3235%2446%9%49%
1260
16th to endNight
7%424425%46%8%48%
1579
August1st to 15thNight
7%424435%5%6%7%48%
1620
16th to endNight
9%5%15%42445%8%46%
1719
September1st to 15thNight
13%425%435%5%6%8%41%
1833
16th to endNight
13%7%35%434447%41%
1815
October1st to 15thNight
21%7%37%6%3435%7%28%
1961
16th to endNight
26%11%38%6%35%445%20%
2168
November1st to 15thNight
18%12%6%8%6%3445%6%23%
2360
16th to endNight
23%17%5%8%7%34445%14%
2520
December1st to 15thNight
21%20%8%12%8%343448%
2544
16th to endNight
23%22%8%12%7%333238%
2880

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
18%20%9%12%9%45%4238%
1316
16th to endDay
15%19%8%14%11%445%339%
1657
February1st to 15thDay
13%18%8%12%9%35%335%15%
1575
16th to endDay
14%16%7%9%8%46%43420%
1500
March1st to 15thDay
13%9%5%8%7%35%45%5%31%
1929
16th to endDay
13%7%47%6%35%5%46%35%
2111
April1st to 15thDay
20%9%45%424346%33%
2165
16th to endDay
18%7%2431335%7%40%
2340
May1st to 15thDay
17%7%25%424447%39%
2337
16th to endDay
12%42442445%8%47%
2621
June1st to 15thDay
12%5%35%5%245%5%8%40%
2700
16th to endDay
10%6%25%5%25%46%9%41%
2700
July1st to 15thDay
8%5%1443445%8%49%
2700
16th to endDay
8%425%32446%9%47%
2584
August1st to 15thDay
10%42442445%7%49%
2340
16th to endDay
11%6%35%42435%9%41%
2483
September1st to 15thDay
13%6%15%5%35%45%7%41%
2033
16th to endDay
16%6%344345%47%38%
1815
October1st to 15thDay
21%8%36%43345%6%30%
1669
16th to endDay
29%12%47%6%3434417%
1702
November1st to 15thDay
19%11%5%8%7%35%5%47%22%
1495
16th to endDay
21%20%6%8%7%35%5%3413%
1440
December1st to 15thDay
19%22%8%12%10%343327%
1413
16th to endDay
22%22%8%13%7%432347%
1344
January1st to 15thNight
20%19%7%13%9%344448%
2621
16th to endNight
15%17%8%12%10%35%34412%
2565
February1st to 15thNight
12%18%8%13%9%3435%5%15%
2278
16th to endNight
14%13%7%11%7%45%45%5%21%
1973
March1st to 15thNight
15%12%46%6%2435%5%30%
2031
16th to endNight
13%7%37%5%34445%38%
2112
April1st to 15thNight
21%8%34424345%36%
1794
16th to endNight
18%7%35%325%45%6%37%
1620
May1st to 15thNight
15%8%35%5%36%347%36%
1610
16th to endNight
12%425%5%45%45%7%43%
1489
June1st to 15thNight
13%6%25%5%25%449%39%
1260
16th to endNight
8%6%245%35%5%6%8%42%
1260
July1st to 15thNight
8%31342447%9%50%
1260
16th to endNight
8%424425%5%6%9%48%
1579
August1st to 15thNight
7%4244245%6%7%48%
1620
16th to endNight
10%425%3345%5%7%47%
1719
September1st to 15thNight
12%425%4345%6%8%41%
1833
16th to endNight
13%7%36%434438%41%
1815
October1st to 15thNight
21%7%37%6%34448%29%
1961
16th to endNight
26%10%48%6%34446%20%
2168
November1st to 15thNight
18%12%49%6%3445%7%23%
2360
16th to endNight
23%16%5%8%6%34445%15%
2520
December1st to 15thNight
21%21%9%12%7%344438%
2544
16th to endNight
23%21%9%11%7%343248%
2880

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
83%5%6%4
1317
16th to endDay
80%5%6%5%1
1657
February1st to 15thDay
73%5%9%9%1
1577
16th to endDay
67%6%9%11%5%
1500
March1st to 15thDay
54%5%12%19%7%
1929
16th to endDay
47%6%13%18%13%2
2112
April1st to 15thDay
51%5%8%21%11%1
2165
16th to endDay
42%6%12%22%14%2
2340
May1st to 15thDay
43%6%8%23%14%2
2337
16th to endDay
35%5%15%25%16%1
2625
June1st to 15thDay
39%7%12%26%12%
2700
16th to endDay
39%7%15%25%12%
2700
July1st to 15thDay
30%6%15%29%16%1
2541
16th to endDay
31%9%15%28%14%1
2424
August1st to 15thDay
32%7%18%27%13%
2327
16th to endDay
39%7%15%26%11%1
2483
September1st to 15thDay
40%7%14%27%9%
2033
16th to endDay
43%7%15%24%8%
1815
October1st to 15thDay
55%5%11%18%9%
1669
16th to endDay
69%6%10%9%3
1702
November1st to 15thDay
63%7%12%11%5%
1495
16th to endDay
75%5%10%7%1
1440
December1st to 15thDay
84%5%6%21
1413
16th to endDay
84%47%3
1344
January1st to 15thNight
81%6%7%4
2621
16th to endNight
76%7%8%5%1
2565
February1st to 15thNight
72%6%8%9%2
2287
16th to endNight
64%6%11%11%5%
1973
March1st to 15thNight
55%5%12%18%6%
2031
16th to endNight
47%410%20%15%2
2112
April1st to 15thNight
49%310%22%12%1
1794
16th to endNight
45%5%9%18%18%2
1620
May1st to 15thNight
47%5%9%19%15%2
1611
16th to endNight
37%7%13%22%17%2
1491
June1st to 15thNight
41%6%10%23%16%1
1260
16th to endNight
38%5%15%25%14%
1260
July1st to 15thNight
28%5%14%29%19%2
1190
16th to endNight
34%8%13%26%17%
1476
August1st to 15thNight
33%7%16%26%15%1
1609
16th to endNight
35%6%17%26%13%1
1719
September1st to 15thNight
39%7%15%24%11%
1833
16th to endNight
44%5%14%25%10%
1815
October1st to 15thNight
55%5%11%17%9%
1961
16th to endNight
67%6%11%11%3
2168
November1st to 15thNight
61%7%12%13%4
2360
16th to endNight
73%5%13%6%
2520
December1st to 15thNight
83%5%6%21
2544
16th to endNight
83%47%4
2880

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
25%14%35%21%4
71
16th to endDay
37%428%23%6%
96
February1st to 15thDay
30%16%32%20%1
90
16th to endDay
30%14%30%22%1
81
March1st to 15thDay
17%20%27%29%4
219
16th to endDay
21%15%25%24%9%3
288
April1st to 15thDay
24%15%25%22%9%1
270
16th to endDay
22%15%26%20%10%4
270
May1st to 15thDay
19%12%23%25%14%4
288
16th to endDay
14%14%20%29%15%5%
334
June1st to 15thDay
12%14%25%31%13%2
495
16th to endDay
13%13%21%30%16%3
495
July1st to 15thDay
10%10%18%34%19%6%
475
16th to endDay
10%12%19%29%22%5%
411
August1st to 15thDay
12%7%15%29%25%9%
313
16th to endDay
18%7%15%26%23%8%
332
September1st to 15thDay
14%8%19%25%21%10%
299
16th to endDay
17%11%18%26%18%7%
254
October1st to 15thDay
22%14%23%26%11%1
255
16th to endDay
30%17%26%19%5%1
214
November1st to 15thDay
12%12%36%32%6%1
75
16th to endDay
21%15%41%20%1
60
December1st to 15thDay
26%25%31%13%3
60
16th to endDay
34%35%25%4
64
January1st to 15thNight
23%30%27%13%4
900
16th to endNight
18%27%24%21%6%1
837
February1st to 15thNight
18%27%29%19%4
704
16th to endNight
18%20%28%24%7%
631
March1st to 15thNight
17%25%25%22%7%1
720
16th to endNight
17%21%22%25%11%1
768
April1st to 15thNight
21%21%24%24%6%1
650
16th to endNight
20%23%20%20%13%
540
May1st to 15thNight
17%18%14%29%18%1
531
16th to endNight
12%20%18%29%17%1
375
June1st to 15thNight
15%18%17%32%14%1
360
16th to endNight
10%18%14%30%25%1
360
July1st to 15thNight
9%12%11%40%22%3
340
16th to endNight
9%17%14%34%20%2
529
August1st to 15thNight
10%12%14%31%25%5%
539
16th to endNight
11%9%16%29%27%5%
573
September1st to 15thNight
13%13%17%27%18%9%
695
16th to endNight
16%12%19%24%21%6%
657
October1st to 15thNight
22%16%22%22%13%2
660
16th to endNight
29%19%25%19%31
704
November1st to 15thNight
19%26%23%20%9%1
700
16th to endNight
26%29%20%17%5%
720
December1st to 15thNight
28%31%24%11%2
744
16th to endNight
27%31%24%13%3
960
Page generated at 2017-09-13 07:39:04. Version ac04

Copyright 2017 A. Danko


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