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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 2019-05-11.

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%
17100
15%
53621
7%
17064
38%
17064
17%
37426

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%
840
14%
2927
4%
836
28%
836
11%
2022
January16th to endNight
13%
896
11%
3073
2%
896
25%
896
9%
2208
February1st to 15thNight
15%
824
13%
2676
3%
821
27%
821
11%
1950
February16th to endNight
17%
735
16%
2215
4%
735
32%
735
15%
1569
March1st to 15thNight
20%
840
16%
2422
5%
840
32%
840
16%
1763
March16th to endNight
25%
896
18%
2464
8%
896
34%
896
21%
1703
April1st to 15thNight
21%
769
17%
2069
5%
769
29%
769
18%
1502
April16th to endNight
31%
623
12%
1869
6%
623
36%
623
18%
1352
May1st to 15thNight
34%
618
14%
1853
9%
618
39%
618
19%
1351
May16th to endNight
36%
535
11%
1670
10%
535
40%
535
16%
1229
June1st to 15thNight
40%
390
10%
1365
11%
390
43%
390
13%
1025
June16th to endNight
46%
390
9%
1365
10%
390
49%
390
17%
952
July1st to 15thNight
52%
370
11%
1400
16%
370
53%
370
18%
914
July16th to endNight
43%
457
10%
1592
11%
432
45%
432
14%
1148
August1st to 15thNight
52%
574
11%
1713
8%
570
53%
570
19%
1212
August16th to endNight
57%
621
17%
1863
11%
621
59%
621
26%
1209
September1st to 15thNight
52%
760
17%
2076
11%
760
56%
760
31%
1348
September16th to endNight
47%
777
24%
2145
16%
777
53%
777
33%
1335
October1st to 15thNight
38%
780
20%
2261
10%
780
47%
780
25%
1501
October16th to endNight
25%
832
17%
2620
7%
832
36%
832
19%
1743
November1st to 15thNight
30%
820
18%
2667
9%
820
42%
820
17%
1785
November16th to endNight
21%
893
14%
2915
4%
893
32%
893
13%
2022
December1st to 15thNight
16%
900
12%
3041
3%
900
27%
900
12%
2195
December16th to endNight
14%
960
12%
3360
1%
960
27%
960
11%
2388

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%424447%37%
54226
Night
20%8%35%42445%7%34%
53795
TransparencyDay
47%6%12%20%12%1
53918
Night
49%5%12%19%11%1
53621
SeeingDay
24%9%28%25%10%1
8571
Night
24%11%27%24%9%1
17101

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
17%8%35%435%3410%33%
1669
16th to endDay
18%9%36%5%2335%7%34%
1852
February1st to 15thDay
18%10%36%445%46%8%27%
1845
16th to endDay
14%10%36%5%35%45%7%33%
1830
March1st to 15thDay
20%10%35%424436%33%
2187
16th to endDay
16%8%24434346%41%
2464
April1st to 15thDay
20%8%25%5%23346%38%
2538
16th to endDay
22%7%35%5%23346%35%
2696
May1st to 15thDay
22%8%36%5%2335%7%32%
2657
16th to endDay
22%8%35%424347%34%
2804
June1st to 15thDay
24%7%26%43445%6%30%
2925
16th to endDay
22%7%35%5%2335%6%33%
2925
July1st to 15thDay
16%5%144335%6%8%39%
2809
16th to endDay
16%7%245%2446%8%35%
2816
August1st to 15thDay
16%6%26%5%3445%8%38%
2488
16th to endDay
12%42442445%7%48%
2691
September1st to 15thDay
12%5%2432435%7%48%
2209
16th to endDay
16%6%13313447%47%
2145
October1st to 15thDay
19%6%13333346%43%
2028
16th to endDay
20%7%24323346%40%
1953
November1st to 15thDay
22%5%36%313436%38%
1851
16th to endDay
21%8%35%423446%35%
1701
December1st to 15thDay
24%8%35%334347%31%
1575
16th to endDay
24%9%35%324347%30%
1568
January1st to 15thNight
16%9%45%5%2345%9%32%
2927
16th to endNight
16%11%36%5%35%5%7%8%26%
3073
February1st to 15thNight
17%9%36%5%35%45%7%30%
2675
16th to endNight
16%10%445%2445%6%35%
2215
March1st to 15thNight
19%11%46%42345%5%32%
2410
16th to endNight
17%7%36%433335%40%
2464
April1st to 15thNight
23%9%36%434436%31%
2069
16th to endNight
26%8%36%423336%31%
1869
May1st to 15thNight
23%8%36%42435%7%30%
1853
16th to endNight
25%9%45%5%33447%28%
1668
June1st to 15thNight
29%10%2442345%7%25%
1365
16th to endNight
24%8%26%32345%6%32%
1365
July1st to 15thNight
19%6%35%5%2435%8%34%
1478
16th to endNight
22%9%26%5%3446%6%28%
1691
August1st to 15thNight
19%9%244345%6%7%32%
1725
16th to endNight
14%6%144345%5%7%41%
1863
September1st to 15thNight
16%5%24424446%45%
2076
16th to endNight
15%5%23323346%48%
2145
October1st to 15thNight
21%6%24323445%41%
2261
16th to endNight
21%7%24323345%40%
2620
November1st to 15thNight
19%6%25%424346%38%
2667
16th to endNight
18%8%35%42445%7%34%
2915
December1st to 15thNight
23%9%25%42445%6%30%
3041
16th to endNight
23%8%25%42445%7%31%
3360

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%6%15%16%9%1
1670
16th to endDay
50%6%15%18%8%
1852
February1st to 15thDay
54%7%15%13%7%
1848
16th to endDay
49%6%13%17%10%2
1830
March1st to 15thDay
52%5%13%17%9%1
2198
16th to endDay
42%5%10%17%19%3
2464
April1st to 15thDay
46%48%20%15%2
2538
16th to endDay
49%410%18%14%3
2696
May1st to 15thDay
51%5%8%19%12%2
2657
16th to endDay
50%6%11%20%9%1
2808
June1st to 15thDay
53%6%10%18%9%1
2925
16th to endDay
51%5%10%18%12%1
2925
July1st to 15thDay
42%6%15%22%12%
2658
16th to endDay
46%7%14%20%9%1
2653
August1st to 15thDay
44%6%13%25%9%
2475
16th to endDay
35%5%13%27%17%
2691
September1st to 15thDay
35%6%12%24%18%2
2209
16th to endDay
36%5%11%27%18%1
2145
October1st to 15thDay
41%5%12%26%13%1
2028
16th to endDay
44%5%13%23%12%
1953
November1st to 15thDay
46%6%12%21%11%1
1851
16th to endDay
50%6%15%17%10%
1701
December1st to 15thDay
53%6%15%18%6%
1575
16th to endDay
55%5%13%15%9%
1568
January1st to 15thNight
49%6%16%18%7%
2927
16th to endNight
54%6%15%15%7%
3073
February1st to 15thNight
53%6%13%15%9%
2676
16th to endNight
50%6%10%18%12%2
2215
March1st to 15thNight
53%5%11%17%11%2
2422
16th to endNight
46%49%17%19%2
2464
April1st to 15thNight
53%48%16%15%3
2069
16th to endNight
54%48%16%12%3
1869
May1st to 15thNight
53%5%8%17%14%1
1853
16th to endNight
56%49%18%9%
1670
June1st to 15thNight
57%7%9%16%6%2
1365
16th to endNight
52%5%11%20%9%
1365
July1st to 15thNight
46%6%13%21%12%
1400
16th to endNight
54%7%11%17%7%1
1592
August1st to 15thNight
48%7%12%21%7%
1713
16th to endNight
40%6%12%22%16%
1863
September1st to 15thNight
38%6%13%24%16%
2076
16th to endNight
36%49%28%20%
2145
October1st to 15thNight
43%410%24%14%1
2261
16th to endNight
46%411%24%12%
2620
November1st to 15thNight
47%5%13%20%12%1
2667
16th to endNight
50%5%15%17%10%1
2915
December1st to 15thNight
54%5%13%17%8%
3041
16th to endNight
53%5%14%16%9%
3360

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
20%32%30%12%11
120
16th to endDay
24%24%36%11%2
188
February1st to 15thDay
25%24%32%13%3
326
16th to endDay
21%14%40%20%2
340
March1st to 15thDay
26%17%36%16%3
390
16th to endDay
23%16%33%20%6%1
416
April1st to 15thDay
27%13%34%18%41
390
16th to endDay
30%6%33%20%8%1
379
May1st to 15thDay
26%7%31%23%8%1
388
16th to endDay
27%327%27%13%
476
June1st to 15thDay
27%125%31%12%
570
16th to endDay
29%120%34%12%1
570
July1st to 15thDay
20%219%35%19%1
442
16th to endDay
22%218%34%18%3
390
August1st to 15thDay
18%320%35%20%1
358
16th to endDay
16%218%33%23%5%
396
September1st to 15thDay
18%124%35%16%2
375
16th to endDay
19%329%28%14%4
374
October1st to 15thDay
22%8%23%29%13%2
339
16th to endDay
25%13%34%22%4
336
November1st to 15thDay
24%19%23%24%6%1
325
16th to endDay
26%19%27%18%6%
330
December1st to 15thDay
28%12%35%18%5%
225
16th to endDay
30%21%35%10%1
128
January1st to 15thNight
20%25%33%16%3
840
16th to endNight
23%24%34%14%3
896
February1st to 15thNight
23%23%35%15%2
824
16th to endNight
22%18%34%19%4
735
March1st to 15thNight
26%14%34%21%3
840
16th to endNight
21%14%33%22%8%
896
April1st to 15thNight
28%8%35%21%5%
769
16th to endNight
30%5%25%28%9%1
623
May1st to 15thNight
26%129%29%11%1
618
16th to endNight
28%322%30%13%1
536
June1st to 15thNight
35%315%30%14%1
390
16th to endNight
29%15%37%15%1
390
July1st to 15thNight
22%113%42%18%1
370
16th to endNight
27%114%34%21%1
457
August1st to 15thNight
25%12%37%22%1
574
16th to endNight
18%113%37%26%3
621
September1st to 15thNight
18%119%39%19%2
760
16th to endNight
18%325%31%16%5%
777
October1st to 15thNight
25%6%23%28%13%2
780
16th to endNight
25%14%31%20%8%
832
November1st to 15thNight
23%13%26%25%9%1
820
16th to endNight
23%19%30%17%8%
893
December1st to 15thNight
28%19%31%16%3
900
16th to endNight
28%21%32%15%2
960
Page generated at 2019-05-12 00:31:06. Version ac04

Copyright 2019 A. Danko


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