Cooke City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cooke City clear sky chart from 2005-11-05 to 2017-12-04.

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
27%
16049
13%
47666
7%
16005
33%
16005
16%
33565

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
17%
900
9%
2628
5%
895
20%
895
10%
2060
January16th to endNight
18%
771
11%
2499
5%
771
26%
771
11%
1831
February1st to 15thNight
16%
701
7%
2288
6%
700
20%
700
8%
1829
February16th to endNight
16%
632
6%
2037
5%
632
19%
632
8%
1638
March1st to 15thNight
17%
720
8%
1989
3%
720
21%
720
11%
1536
March16th to endNight
18%
768
6%
2112
2%
768
21%
768
10%
1655
April1st to 15thNight
23%
566
7%
1813
3%
566
26%
566
12%
1327
April16th to endNight
25%
540
10%
1620
5%
540
29%
540
12%
1191
May1st to 15thNight
35%
539
11%
1551
6%
539
40%
539
18%
1062
May16th to endNight
34%
563
6%
1498
3%
561
38%
561
15%
1115
June1st to 15thNight
33%
451
9%
1351
4%
451
37%
451
18%
937
June16th to endNight
47%
360
18%
1260
12%
360
56%
360
29%
652
July1st to 15thNight
61%
343
16%
1193
14%
343
68%
343
33%
619
July16th to endNight
44%
564
24%
1495
14%
531
58%
531
43%
766
August1st to 15thNight
53%
539
22%
1611
14%
536
61%
536
32%
879
August16th to endNight
51%
573
29%
1749
18%
573
60%
573
35%
912
September1st to 15thNight
44%
561
22%
1821
13%
561
56%
561
29%
1003
September16th to endNight
43%
716
22%
1986
13%
716
50%
716
31%
1217
October1st to 15thNight
35%
720
17%
2160
9%
720
42%
720
19%
1479
October16th to endNight
31%
768
20%
2312
10%
768
40%
768
21%
1520
November1st to 15thNight
16%
899
12%
2609
5%
899
23%
899
14%
1918
November16th to endNight
16%
975
11%
2730
4%
975
23%
975
13%
2024
December1st to 15thNight
13%
920
6%
2576
3%
920
16%
920
8%
2116
December16th to endNight
13%
960
9%
2778
3%
960
19%
960
7%
2279

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
7%14%6%9%7%34446%32%
48836
Night
5%12%6%10%7%34446%34%
47833
Cloud CoverDay
6%12%5%10%7%35%45%6%32%
48837
Night
39%5%10%8%35%5%5%7%35%
47835
TransparencyDay
53%5%12%16%10%2
48507
Night
49%6%14%18%9%2
47666
SeeingDay
19%24%25%18%9%2
6212
Night
14%29%22%22%9%1
16053

By Month

Percentage Cloud Cover NW (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
217%12%17%7%2444423%
1313
16th to endDay
115%11%16%9%33335%26%
1728
February1st to 15thDay
219%12%18%8%23235%22%
1575
16th to endDay
117%12%20%15%3322317%
1437
March1st to 15thDay
121%9%13%9%33446%23%
1971
16th to endDay
6%23%9%11%7%34435%18%
2111
April1st to 15thDay
7%23%11%13%6%23346%17%
2132
16th to endDay
6%24%8%11%7%34246%20%
2340
May1st to 15thDay
9%15%5%10%6%35%5%5%5%26%
2399
16th to endDay
14%17%5%9%7%35%5%5%5%19%
2616
June1st to 15thDay
16%12%36%5%35%5%5%7%27%
2605
16th to endDay
5%6%35%5%35%5%6%7%46%
2700
July1st to 15thDay
5%4245%36%6%6%9%44%
2694
16th to endDay
5%325%5%3345%6%53%
2567
August1st to 15thDay
7%5%25%6%36%6%5%7%43%
2340
16th to endDay
6%415%5%3445%6%52%
2453
September1st to 15thDay
11%6%25%5%2334450%
2137
16th to endDay
10%9%25%5%33446%43%
1974
October1st to 15thDay
11%18%46%423346%34%
1800
16th to endDay
9%17%5%8%323346%35%
1911
November1st to 15thDay
9%16%7%9%5%23346%29%
1567
16th to endDay
416%7%13%6%2343431%
1560
December1st to 15thDay
319%8%15%10%5%6%5%45%15%
1466
16th to endDay
418%8%17%12%4324418%
1440
January1st to 15thNight
217%11%15%7%45%33422%
2628
16th to endNight
112%10%16%10%34336%27%
2499
February1st to 15thNight
316%9%17%9%34445%20%
2277
16th to endNight
116%9%18%12%24445%19%
2037
March1st to 15thNight
118%10%12%7%34346%28%
1989
16th to endNight
420%6%9%7%25%5%47%25%
2109
April1st to 15thNight
5%16%7%9%5%3445%7%29%
1813
16th to endNight
5%14%48%6%35%5%6%7%32%
1620
May1st to 15thNight
5%12%5%6%6%23447%40%
1550
16th to endNight
9%10%36%7%38%7%7%8%28%
1498
June1st to 15thNight
12%9%25%5%35%5%5%8%35%
1351
16th to endNight
6%5%332445%7%57%
1260
July1st to 15thNight
4212426%6%7%10%52%
1263
16th to endNight
231332445%7%62%
1598
August1st to 15thNight
3213435%6%6%10%50%
1620
16th to endNight
431332445%5%60%
1749
September1st to 15thNight
7%41432445%6%54%
1821
16th to endNight
8%8%24322346%51%
1986
October1st to 15thNight
9%12%36%425%45%6%40%
2160
16th to endNight
7%12%46%42235%7%42%
2312
November1st to 15thNight
7%17%6%10%6%22346%30%
2609
16th to endNight
416%7%11%7%33336%31%
2730
December1st to 15thNight
218%9%15%12%35%5%4417%
2576
16th to endNight
414%9%17%13%45%33419%
2778

Percentage Cloud Cover SW (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%8%18%11%46%5%5%7%23%
1313
16th to endDay
10%8%16%10%5%4446%27%
1728
February1st to 15thDay
113%9%20%11%34345%21%
1575
16th to endDay
13%10%18%18%3433417%
1437
March1st to 15thDay
15%8%15%10%46%35%6%23%
1971
16th to endDay
420%10%13%9%44345%18%
2112
April1st to 15thDay
5%21%10%13%8%3345%6%16%
2132
16th to endDay
5%22%9%12%6%35%445%21%
2340
May1st to 15thDay
7%17%5%10%7%36%446%26%
2399
16th to endDay
13%17%6%9%7%45%5%46%19%
2616
June1st to 15thDay
14%12%46%5%35%5%6%7%26%
2605
16th to endDay
5%6%25%5%346%6%7%47%
2700
July1st to 15thDay
6%4245%35%6%6%9%44%
2694
16th to endDay
4425%5%35%45%6%52%
2567
August1st to 15thDay
7%5%26%6%35%5%5%6%42%
2340
16th to endDay
6%5%25%5%2445%6%51%
2453
September1st to 15thDay
11%7%25%423335%50%
2137
16th to endDay
8%11%25%5%24446%44%
1974
October1st to 15thDay
9%16%47%424446%34%
1800
16th to endDay
6%13%6%9%6%23346%36%
1911
November1st to 15thDay
5%14%5%11%6%3436%7%30%
1567
16th to endDay
212%8%12%8%345%46%31%
1560
December1st to 15thDay
113%8%15%12%5%8%6%5%6%16%
1466
16th to endDay
211%8%19%14%5%5%446%19%
1440
January1st to 15thNight
17%8%17%12%47%6%35%24%
2628
16th to endNight
7%6%14%13%5%6%447%28%
2499
February1st to 15thNight
111%7%17%13%5%6%446%21%
2277
16th to endNight
111%9%18%13%445%46%20%
2037
March1st to 15thNight
12%8%15%9%35%447%28%
1989
16th to endNight
215%5%11%9%35%5%7%7%25%
2112
April1st to 15thNight
313%6%12%6%3447%7%30%
1813
16th to endNight
413%47%7%35%5%7%7%32%
1620
May1st to 15thNight
411%5%7%7%335%5%6%39%
1550
16th to endNight
7%11%38%6%37%7%7%9%27%
1497
June1st to 15thNight
10%8%27%6%35%5%6%7%36%
1351
16th to endNight
4413424447%57%
1260
July1st to 15thNight
2213335%6%7%8%53%
1263
16th to endNight
331332436%7%61%
1598
August1st to 15thNight
3413426%6%5%9%51%
1620
16th to endNight
431333436%6%59%
1749
September1st to 15thNight
7%415%334447%53%
1821
16th to endNight
6%7%26%313446%51%
1986
October1st to 15thNight
6%10%36%6%35%5%5%7%39%
2160
16th to endNight
5%9%47%5%2335%8%43%
2312
November1st to 15thNight
5%12%6%11%8%2445%6%31%
2609
16th to endNight
211%5%12%8%45%448%32%
2730
December1st to 15thNight
10%7%14%15%6%8%7%5%5%18%
2576
16th to endNight
210%8%16%15%5%6%5%4420%
2778

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
61%6%11%13%6%2
1313
16th to endDay
59%6%12%11%8%2
1728
February1st to 15thDay
67%5%11%11%3
1575
16th to endDay
72%47%9%41
1437
March1st to 15thDay
63%5%14%11%4
1971
16th to endDay
70%5%11%10%1
2112
April1st to 15thDay
68%5%10%12%2
2132
16th to endDay
66%414%10%2
2340
May1st to 15thDay
58%317%17%2
2399
16th to endDay
65%6%15%10%1
2620
June1st to 15thDay
53%5%16%17%5%
2605
16th to endDay
33%5%14%27%16%3
2700
July1st to 15thDay
34%5%13%23%18%5%
2535
16th to endDay
31%46%17%27%11%
2407
August1st to 15thDay
40%5%9%18%20%6%
2325
16th to endDay
34%47%25%20%7%
2453
September1st to 15thDay
38%45%22%25%3
2137
16th to endDay
42%412%24%13%2
1974
October1st to 15thDay
52%414%19%8%1
1800
16th to endDay
50%6%14%18%9%
1911
November1st to 15thDay
55%6%12%15%7%2
1567
16th to endDay
53%6%16%16%5%
1560
December1st to 15thDay
66%7%11%8%5%
1466
16th to endDay
67%5%10%11%41
1440
January1st to 15thNight
59%7%12%12%5%2
2628
16th to endNight
55%6%14%13%7%2
2499
February1st to 15thNight
64%6%9%12%7%
2288
16th to endNight
66%5%10%10%5%2
2037
March1st to 15thNight
57%7%14%13%6%1
1989
16th to endNight
57%8%16%13%3
2112
April1st to 15thNight
54%6%18%16%4
1813
16th to endNight
52%8%19%15%3
1620
May1st to 15thNight
45%5%20%23%4
1551
16th to endNight
52%7%23%14%3
1498
June1st to 15thNight
46%6%18%21%7%
1351
16th to endNight
26%5%17%30%17%3
1260
July1st to 15thNight
24%7%18%26%17%5%
1193
16th to endNight
21%38%25%29%11%
1495
August1st to 15thNight
28%414%24%20%6%
1611
16th to endNight
25%310%31%23%6%
1749
September1st to 15thNight
30%410%24%26%2
1821
16th to endNight
34%5%15%29%14%1
1986
October1st to 15thNight
45%5%17%20%9%1
2160
16th to endNight
40%7%16%25%9%
2312
November1st to 15thNight
53%5%14%17%6%2
2609
16th to endNight
52%7%16%13%8%1
2730
December1st to 15thNight
65%6%10%12%4
2576
16th to endNight
66%6%8%12%5%1
2778

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
13%15%27%20%17%5%
69
16th to endDay
8%29%30%18%10%3
96
February1st to 15thDay
35%16%33%10%22
90
16th to endDay
30%26%27%11%41
96
March1st to 15thDay
30%43%17%5%3
270
16th to endDay
27%36%21%12%1
288
April1st to 15thDay
24%35%29%8%1
269
16th to endDay
25%30%26%12%3
270
May1st to 15thDay
17%22%26%19%9%3
356
16th to endDay
24%22%16%17%15%4
517
June1st to 15thDay
18%21%20%21%14%3
495
16th to endDay
11%22%24%25%14%2
495
July1st to 15thDay
9%19%19%24%22%5%
475
16th to endDay
10%23%31%22%9%1
426
August1st to 15thDay
15%21%32%23%5%
315
16th to endDay
12%23%31%21%8%2
332
September1st to 15thDay
21%25%27%18%42
315
16th to endDay
22%26%27%13%8%1
309
October1st to 15thDay
24%22%28%17%6%
135
16th to endDay
31%20%18%24%5%
144
November1st to 15thDay
23%15%26%15%12%5%
135
16th to endDay
21%24%36%15%2
135
December1st to 15thDay
36%14%22%19%9%
100
16th to endDay
23%18%28%16%6%6%
80
January1st to 15thNight
15%37%24%15%5%1
900
16th to endNight
15%33%25%18%5%1
771
February1st to 15thNight
16%33%25%18%5%
704
16th to endNight
16%34%24%15%8%
632
March1st to 15thNight
20%35%21%17%41
720
16th to endNight
17%35%22%17%5%
768
April1st to 15thNight
13%33%23%21%6%1
566
16th to endNight
14%31%21%20%10%1
540
May1st to 15thNight
12%28%14%28%12%2
540
16th to endNight
15%24%17%25%14%1
563
June1st to 15thNight
15%24%18%26%12%1
451
16th to endNight
8%21%17%33%16%1
360
July1st to 15thNight
5%14%14%31%30%3
343
16th to endNight
6%21%23%33%14%1
564
August1st to 15thNight
6%14%19%37%20%1
539
16th to endNight
8%14%20%34%20%2
573
September1st to 15thNight
11%16%23%30%14%3
561
16th to endNight
13%15%22%26%18%3
716
October1st to 15thNight
16%21%20%28%11%1
720
16th to endNight
16%23%25%23%8%2
768
November1st to 15thNight
17%33%27%15%5%1
899
16th to endNight
19%36%23%17%2
975
December1st to 15thNight
18%38%22%14%41
920
16th to endNight
14%38%25%13%6%1
960
Page generated at 2017-12-05 08:19:01. Version ac04

Copyright 2017 A. Danko


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