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Cadillac Mountain Summit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cadillac Mountain Summit clear sky chart from 2005-11-05 to 2017-09-10.

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
30%
14836
14%
46728
7%
14800
38%
14800
17%
32669

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
15%
720
13%
2507
4%
716
27%
716
11%
1744
January16th to endNight
13%
768
12%
2634
2%
768
26%
768
10%
1878
February1st to 15thNight
14%
704
10%
2286
2%
701
25%
701
11%
1692
February16th to endNight
19%
631
16%
1901
4%
631
33%
631
15%
1356
March1st to 15thNight
20%
720
15%
2076
5%
720
31%
720
16%
1510
March16th to endNight
25%
768
18%
2112
8%
768
34%
768
20%
1480
April1st to 15thNight
23%
659
17%
1773
5%
659
30%
659
19%
1285
April16th to endNight
33%
540
13%
1620
6%
540
38%
540
19%
1151
May1st to 15thNight
34%
540
13%
1620
9%
540
39%
540
18%
1184
May16th to endNight
36%
493
11%
1538
10%
493
40%
493
16%
1134
June1st to 15thNight
39%
360
9%
1260
10%
360
42%
360
12%
956
June16th to endNight
46%
360
8%
1260
9%
360
48%
360
17%
890
July1st to 15thNight
50%
340
9%
1286
14%
340
51%
340
17%
849
July16th to endNight
43%
421
9%
1460
11%
396
46%
396
14%
1048
August1st to 15thNight
53%
539
11%
1608
8%
535
55%
535
20%
1126
August16th to endNight
56%
573
17%
1719
11%
573
59%
573
25%
1126
September1st to 15thNight
51%
682
16%
1861
10%
682
55%
682
31%
1207
September16th to endNight
49%
657
26%
1815
17%
657
55%
657
37%
1082
October1st to 15thNight
37%
660
20%
1913
11%
660
46%
660
24%
1268
October16th to endNight
25%
704
17%
2216
7%
704
36%
704
20%
1482
November1st to 15thNight
33%
700
18%
2277
11%
700
43%
700
19%
1515
November16th to endNight
23%
747
14%
2499
5%
747
34%
747
14%
1731
December1st to 15thNight
16%
750
11%
2607
3%
750
26%
750
12%
1892
December16th to endNight
14%
800
11%
2880
1%
800
26%
800
10%
2083

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
19%7%25%42445%7%36%
47891
Night
20%8%35%42445%6%34%
46902
TransparencyDay
47%6%12%20%12%1
47583
Night
50%5%12%19%11%1
46728
SeeingDay
24%8%27%26%11%1
6492
Night
24%10%27%25%10%1
14837

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
16%9%35%4343410%34%
1429
16th to endDay
18%9%35%5%2345%7%34%
1587
February1st to 15thDay
17%9%36%446%5%6%8%27%
1575
16th to endDay
13%9%46%5%35%5%5%7%32%
1572
March1st to 15thDay
20%9%35%424437%33%
1873
16th to endDay
16%8%24434346%40%
2112
April1st to 15thDay
20%7%24423346%38%
2174
16th to endDay
20%7%35%5%24347%36%
2340
May1st to 15thDay
23%7%36%5%2335%7%31%
2332
16th to endDay
23%7%35%424247%33%
2584
June1st to 15thDay
25%7%27%43445%6%28%
2700
16th to endDay
23%7%35%42335%7%32%
2700
July1st to 15thDay
17%5%144335%6%8%38%
2593
16th to endDay
16%7%245%3446%8%35%
2597
August1st to 15thDay
16%6%15%5%3345%8%39%
2340
16th to endDay
12%42442445%7%47%
2483
September1st to 15thDay
13%5%2432435%7%48%
1983
16th to endDay
16%5%13213446%49%
1815
October1st to 15thDay
19%5%14433346%41%
1716
16th to endDay
21%7%24333346%39%
1653
November1st to 15thDay
22%5%35%314446%38%
1581
16th to endDay
20%8%35%4235%46%35%
1458
December1st to 15thDay
25%8%35%334347%30%
1350
16th to endDay
25%9%35%324246%30%
1344
January1st to 15thNight
16%9%45%5%2445%9%32%
2507
16th to endNight
16%11%35%5%35%5%7%8%26%
2634
February1st to 15thNight
16%10%36%6%35%46%7%28%
2285
16th to endNight
15%10%5%5%5%2445%6%34%
1901
March1st to 15thNight
20%10%46%42345%5%32%
2064
16th to endNight
18%7%36%434336%38%
2112
April1st to 15thNight
22%9%36%433436%32%
1773
16th to endNight
24%8%36%423346%32%
1620
May1st to 15thNight
24%7%36%43425%6%30%
1620
16th to endNight
25%9%45%423447%28%
1536
June1st to 15thNight
30%10%2443345%7%23%
1260
16th to endNight
24%8%26%32445%6%31%
1260
July1st to 15thNight
20%6%35%5%2445%8%32%
1364
16th to endNight
21%8%26%5%35%46%6%28%
1559
August1st to 15thNight
18%8%244345%6%7%33%
1620
16th to endNight
15%6%14435%5%5%7%40%
1719
September1st to 15thNight
17%424324446%45%
1861
16th to endNight
14%413223345%53%
1815
October1st to 15thNight
21%6%24333345%40%
1913
16th to endNight
21%7%35%323345%39%
2216
November1st to 15thNight
19%6%25%42445%6%38%
2277
16th to endNight
19%7%35%42446%5%35%
2499
December1st to 15thNight
25%8%25%42445%6%29%
2607
16th to endNight
24%8%35%42345%6%30%
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
49%7%14%17%9%1
1430
16th to endDay
49%6%17%18%7%
1587
February1st to 15thDay
54%8%15%14%7%
1578
16th to endDay
49%7%13%17%10%1
1572
March1st to 15thDay
51%6%12%17%10%1
1884
16th to endDay
43%6%11%18%17%3
2112
April1st to 15thDay
46%48%21%16%2
2174
16th to endDay
47%5%10%18%14%3
2340
May1st to 15thDay
51%5%9%18%12%2
2332
16th to endDay
52%5%11%20%9%1
2588
June1st to 15thDay
55%6%10%17%7%1
2700
16th to endDay
51%5%10%18%12%1
2700
July1st to 15thDay
43%6%16%22%10%
2442
16th to endDay
46%7%15%21%9%
2434
August1st to 15thDay
44%5%14%25%10%
2327
16th to endDay
36%5%13%26%17%
2483
September1st to 15thDay
35%7%12%24%17%2
1983
16th to endDay
34%5%10%28%19%1
1815
October1st to 15thDay
41%5%11%25%14%1
1716
16th to endDay
45%5%13%24%11%
1653
November1st to 15thDay
46%6%13%20%12%
1581
16th to endDay
50%6%14%15%11%
1458
December1st to 15thDay
54%7%15%17%5%
1350
16th to endDay
56%5%14%15%8%
1344
January1st to 15thNight
50%6%15%18%6%
2507
16th to endNight
53%6%15%16%7%
2634
February1st to 15thNight
55%6%14%14%7%
2286
16th to endNight
50%6%11%18%11%1
1901
March1st to 15thNight
53%5%10%17%11%2
2076
16th to endNight
47%410%18%17%2
2112
April1st to 15thNight
52%38%16%15%2
1773
16th to endNight
52%49%17%13%3
1620
May1st to 15thNight
53%5%8%16%14%1
1620
16th to endNight
56%49%18%9%
1538
June1st to 15thNight
58%7%10%16%5%1
1260
16th to endNight
53%5%11%19%9%
1260
July1st to 15thNight
47%6%13%20%10%
1286
16th to endNight
53%7%12%17%7%1
1460
August1st to 15thNight
47%7%13%22%8%
1608
16th to endNight
41%6%13%22%15%
1719
September1st to 15thNight
38%6%13%24%15%
1861
16th to endNight
32%48%31%22%
1815
October1st to 15thNight
44%49%24%15%2
1913
16th to endNight
46%411%24%12%
2216
November1st to 15thNight
47%5%13%20%12%
2277
16th to endNight
50%5%15%16%10%1
2499
December1st to 15thNight
54%6%14%17%6%
2607
16th to endNight
55%5%14%15%8%
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
16%33%31%18%
60
16th to endDay
21%23%35%14%3
115
February1st to 15thDay
22%22%36%14%4
236
16th to endDay
18%13%39%24%3
238
March1st to 15thDay
24%17%37%17%3
270
16th to endDay
25%14%31%20%6%1
288
April1st to 15thDay
27%10%34%19%6%1
270
16th to endDay
27%5%38%18%9%2
270
May1st to 15thDay
29%8%27%23%8%2
288
16th to endDay
29%326%26%12%
406
June1st to 15thDay
29%224%30%12%1
495
16th to endDay
30%119%33%13%2
495
July1st to 15thDay
23%220%33%19%1
376
16th to endDay
21%218%35%19%2
326
August1st to 15thDay
19%221%34%20%1
313
16th to endDay
17%218%34%21%5%
332
September1st to 15thDay
20%225%32%15%3
294
16th to endDay
19%325%29%16%5%
254
October1st to 15thDay
22%10%22%27%14%2
237
16th to endDay
26%10%34%22%5%
240
November1st to 15thDay
24%17%23%25%7%2
235
16th to endDay
25%21%27%17%7%1
240
December1st to 15thDay
31%13%32%18%4
150
16th to endDay
32%21%32%12%
64
January1st to 15thNight
20%24%33%17%3
720
16th to endNight
23%23%35%15%2
768
February1st to 15thNight
22%21%37%15%2
704
16th to endNight
21%17%34%20%4
631
March1st to 15thNight
26%14%32%22%4
720
16th to endNight
21%13%33%22%8%
768
April1st to 15thNight
28%7%35%22%6%
659
16th to endNight
27%5%25%29%9%1
540
May1st to 15thNight
27%128%29%10%2
540
16th to endNight
28%321%30%13%1
494
June1st to 15thNight
35%315%29%14%1
360
16th to endNight
29%15%35%16%1
360
July1st to 15thNight
24%112%41%18%
340
16th to endNight
25%114%35%21%1
421
August1st to 15thNight
24%12%37%23%1
539
16th to endNight
19%113%37%25%3
573
September1st to 15thNight
19%119%37%19%2
682
16th to endNight
17%226%30%17%5%
657
October1st to 15thNight
26%7%22%27%13%2
660
16th to endNight
25%12%32%20%7%
704
November1st to 15thNight
22%10%28%27%10%1
700
16th to endNight
23%17%30%18%9%
747
December1st to 15thNight
30%18%30%16%3
750
16th to endNight
29%19%33%15%2
800
Page generated at 2017-09-11 19:35:28. Version ac04

Copyright 2017 A. Danko


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