Black Kettle National Grasslands
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Black Kettle National Grasslands clear sky chart from 2005-11-05 to 2017-10-06.

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
45%
15807
30%
47153
17%
15762
58%
15762
42%
24804

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
41%
900
33%
2327
14%
895
54%
895
48%
1257
January16th to endNight
41%
936
38%
2472
16%
936
55%
936
52%
1269
February1st to 15thNight
36%
704
29%
2112
13%
700
51%
700
37%
1156
February16th to endNight
30%
632
33%
1894
12%
632
47%
632
35%
1030
March1st to 15thNight
34%
651
29%
2091
14%
651
48%
651
35%
1119
March16th to endNight
30%
576
25%
2112
12%
576
48%
576
31%
1068
April1st to 15thNight
28%
539
26%
1843
11%
539
48%
539
32%
954
April16th to endNight
28%
540
28%
1701
13%
540
49%
540
34%
935
May1st to 15thNight
37%
539
29%
1620
17%
539
55%
539
38%
883
May16th to endNight
43%
561
25%
1684
16%
561
57%
561
40%
923
June1st to 15thNight
45%
540
22%
1620
12%
540
55%
540
44%
831
June16th to endNight
56%
540
25%
1620
17%
540
65%
540
48%
829
July1st to 15thNight
66%
510
21%
1530
19%
510
70%
510
45%
802
July16th to endNight
79%
564
31%
1594
32%
531
81%
531
53%
779
August1st to 15thNight
75%
539
25%
1632
28%
536
77%
536
42%
872
August16th to endNight
71%
573
23%
1910
26%
573
75%
573
38%
1004
September1st to 15thNight
61%
540
25%
1933
23%
540
69%
540
36%
1007
September16th to endNight
53%
537
33%
1980
25%
537
67%
537
40%
958
October1st to 15thNight
48%
513
36%
1881
26%
513
62%
513
36%
941
October16th to endNight
48%
738
38%
2146
17%
738
62%
738
57%
1001
November1st to 15thNight
46%
875
35%
2275
12%
875
58%
875
53%
1160
November16th to endNight
41%
900
36%
2340
14%
900
54%
900
49%
1242
December1st to 15thNight
37%
900
32%
2340
12%
900
50%
900
43%
1322
December16th to endNight
36%
960
34%
2496
15%
960
50%
960
38%
1462

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%423323346%56%
48041
Night
6%313323347%59%
47349
Cloud CoverDay
7%423323446%56%
48039
Night
6%313323347%59%
47349
TransparencyDay
27%39%25%24%9%
47739
Night
25%39%24%26%11%
47154
SeeingDay
9%6%27%32%20%3
5782
Night
8%7%33%35%12%
15810

By Month

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
5%5%23323225%62%
1611
16th to endDay
5%323313245%61%
1761
February1st to 15thDay
5%6%24322336%60%
1750
16th to endDay
6%5%33213235%63%
1580
March1st to 15thDay
8%5%24223346%54%
1869
16th to endDay
9%424313245%56%
2112
April1st to 15thDay
9%313323346%56%
2102
16th to endDay
11%423423346%53%
2259
May1st to 15thDay
10%423334446%53%
2331
16th to endDay
7%4244345%5%8%49%
2430
June1st to 15thDay
5%223425%46%9%54%
2340
16th to endDay
431343445%7%57%
2340
July1st to 15thDay
6%4134345%6%8%50%
2340
16th to endDay
421332445%8%58%
2466
August1st to 15thDay
43245%35%5%7%9%50%
2315
16th to endDay
6%3134345%6%9%52%
2292
September1st to 15thDay
11%31342445%6%51%
2025
16th to endDay
431331446%6%59%
1980
October1st to 15thDay
12%414312225%58%
1873
16th to endDay
431332223467%
1714
November1st to 15thDay
4212312246%67%
1583
16th to endDay
6%423212225%66%
1620
December1st to 15thDay
8%5%24312346%57%
1620
16th to endDay
10%7%24423325%54%
1728
January1st to 15thNight
5%313323445%64%
2327
16th to endNight
5%412212235%67%
2472
February1st to 15thNight
7%5%24323235%58%
2102
16th to endNight
7%5%13423345%57%
1894
March1st to 15thNight
7%32442335%6%56%
2091
16th to endNight
8%413323245%58%
2112
April1st to 15thNight
6%32432345%6%56%
1843
16th to endNight
10%42332335%6%55%
1701
May1st to 15thNight
8%324213246%60%
1619
16th to endNight
7%2123245%5%9%54%
1683
June1st to 15thNight
41123335%7%10%55%
1620
16th to endNight
4113225%5%6%9%58%
1620
July1st to 15thNight
5%2143335%5%7%57%
1620
16th to endNight
321331335%10%61%
1702
August1st to 15thNight
3313426%5%5%10%52%
1642
16th to endNight
5%313325%5%6%10%51%
1910
September1st to 15thNight
8%31432335%7%55%
1933
16th to endNight
6%41232335%7%58%
1980
October1st to 15thNight
9%313312346%60%
1881
16th to endNight
42221223473%
2146
November1st to 15thNight
3212223346%67%
2275
16th to endNight
6%21222323466%
2340
December1st to 15thNight
7%414323337%58%
2340
16th to endNight
10%6%23213335%56%
2496

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
5%5%2331333462%
1611
16th to endDay
5%313414345%61%
1761
February1st to 15thDay
5%6%24322335%60%
1750
16th to endDay
6%5%33212235%63%
1580
March1st to 15thDay
9%5%24323346%54%
1869
16th to endDay
9%5%24323345%56%
2110
April1st to 15thDay
9%31332335%6%56%
2102
16th to endDay
11%323323446%53%
2259
May1st to 15thDay
10%323324445%53%
2331
16th to endDay
8%424425%5%5%8%49%
2430
June1st to 15thDay
5%3224235%6%9%54%
2340
16th to endDay
4313334347%58%
2340
July1st to 15thDay
7%3134345%6%8%51%
2340
16th to endDay
421332445%8%58%
2466
August1st to 15thDay
4214435%5%7%9%50%
2315
16th to endDay
6%3134245%6%9%52%
2292
September1st to 15thDay
10%41343445%5%51%
2025
16th to endDay
43134235%5%6%59%
1980
October1st to 15thDay
12%414312225%58%
1873
16th to endDay
432332233467%
1714
November1st to 15thDay
4212312246%67%
1583
16th to endDay
6%42223225%66%
1620
December1st to 15thDay
8%5%24312336%57%
1620
16th to endDay
10%6%23413325%55%
1728
January1st to 15thNight
5%313312345%64%
2327
16th to endNight
6%312212235%67%
2472
February1st to 15thNight
7%5%24323235%58%
2102
16th to endNight
7%414423345%57%
1894
March1st to 15thNight
7%32443235%6%56%
2091
16th to endNight
8%423423245%58%
2112
April1st to 15thNight
7%42332335%7%56%
1843
16th to endNight
11%41331245%7%54%
1701
May1st to 15thNight
8%324213346%60%
1619
16th to endNight
7%2123245%6%9%54%
1683
June1st to 15thNight
41124335%7%10%55%
1620
16th to endNight
4112225%5%5%9%58%
1620
July1st to 15thNight
5%2133235%5%7%57%
1620
16th to endNight
32321335%11%61%
1702
August1st to 15thNight
4313435%5%5%10%52%
1642
16th to endNight
5%2234245%6%10%51%
1910
September1st to 15thNight
8%31332335%7%56%
1933
16th to endNight
7%31342335%8%57%
1980
October1st to 15thNight
9%313312336%60%
1881
16th to endNight
421221222473%
2146
November1st to 15thNight
3212223346%67%
2275
16th to endNight
6%212213335%66%
2340
December1st to 15thNight
8%413323346%58%
2340
16th to endNight
10%6%14213235%57%
2496

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
26%17%26%30%6%
1612
16th to endDay
24%26%28%30%7%
1761
February1st to 15thDay
27%27%28%25%9%
1751
16th to endDay
24%15%28%27%12%
1580
March1st to 15thDay
30%28%23%22%11%
1869
16th to endDay
31%29%25%20%10%
2112
April1st to 15thDay
28%29%21%24%12%
2102
16th to endDay
32%38%24%23%8%
2259
May1st to 15thDay
32%310%18%23%11%
2331
16th to endDay
32%412%23%18%7%
2434
June1st to 15thDay
26%413%28%18%9%
2340
16th to endDay
24%411%24%22%11%
2340
July1st to 15thDay
29%49%24%26%5%
2201
16th to endDay
22%411%30%25%5%
2311
August1st to 15thDay
28%5%13%27%17%7%
2301
16th to endDay
27%5%10%27%21%7%
2292
September1st to 15thDay
32%412%23%18%8%
2025
16th to endDay
24%48%26%29%7%
1980
October1st to 15thDay
30%29%21%26%9%
1873
16th to endDay
21%17%22%31%14%
1714
November1st to 15thDay
19%25%26%29%17%
1583
16th to endDay
23%1424%32%14%
1620
December1st to 15thDay
29%29%26%26%6%
1620
16th to endDay
33%27%23%25%7%
1728
January1st to 15thNight
22%27%26%32%8%
2327
16th to endNight
20%17%25%32%12%
2472
February1st to 15thNight
29%26%23%26%10%
2112
16th to endNight
28%25%24%25%13%
1894
March1st to 15thNight
28%37%23%25%10%
2091
16th to endNight
28%310%25%20%10%
2112
April1st to 15thNight
27%410%20%24%12%
1843
16th to endNight
29%48%25%22%9%
1701
May1st to 15thNight
27%49%19%26%12%
1620
16th to endNight
25%5%15%23%21%8%
1685
June1st to 15thNight
21%6%15%30%19%7%
1620
16th to endNight
21%413%26%22%10%
1620
July1st to 15thNight
24%313%26%23%8%
1530
16th to endNight
19%312%28%29%6%
1594
August1st to 15thNight
25%415%24%20%9%
1632
16th to endNight
27%5%12%24%22%8%
1910
September1st to 15thNight
28%412%26%18%10%
1933
16th to endNight
25%310%24%27%8%
1980
October1st to 15thNight
26%38%23%27%9%
1881
16th to endNight
16%15%23%34%17%
2146
November1st to 15thNight
18%26%24%29%17%
2275
16th to endNight
21%2423%29%18%
2340
December1st to 15thNight
26%29%25%27%7%
2340
16th to endNight
30%27%21%27%10%
2496

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
15%7%32%30%12%2
90
16th to endDay
314%54%21%6%
96
February1st to 15thDay
8%12%36%26%14%1
90
16th to endDay
211%55%20%9%
81
March1st to 15thDay
12%16%54%16%
90
16th to endDay
8%11%43%25%11%
96
April1st to 15thDay
13%23%34%24%3
221
16th to endDay
16%17%39%19%5%1
369
May1st to 15thDay
11%10%38%28%8%1
468
16th to endDay
12%7%33%28%16%2
517
June1st to 15thDay
6%431%34%18%3
495
16th to endDay
5%223%41%23%4
495
July1st to 15thDay
8%14%42%27%6%
475
16th to endDay
5%5%41%38%8%
515
August1st to 15thDay
6%19%42%37%2
468
16th to endDay
6%215%41%27%6%
332
September1st to 15thDay
6%15%37%31%8%
180
16th to endDay
13%123%29%25%6%
135
October1st to 15thDay
11%340%20%20%3
107
16th to endDay
5%236%32%18%5%
96
November1st to 15thDay
10%8%30%27%20%3
90
16th to endDay
17%18%34%16%10%2
90
December1st to 15thDay
11%8%52%17%10%
90
16th to endDay
17%14%42%19%5%
96
January1st to 15thNight
7%11%36%35%8%
900
16th to endNight
7%8%40%34%8%
936
February1st to 15thNight
11%8%39%32%6%
704
16th to endNight
11%14%41%25%6%
632
March1st to 15thNight
9%10%42%31%5%
651
16th to endNight
11%14%41%28%4
576
April1st to 15thNight
10%13%44%27%3
539
16th to endNight
13%11%44%25%4
540
May1st to 15thNight
11%9%39%31%7%
540
16th to endNight
7%6%37%30%15%1
563
June1st to 15thNight
5%441%35%11%1
540
16th to endNight
5%132%44%15%
540
July1st to 15thNight
6%18%50%21%1
510
16th to endNight
5%9%51%30%2
564
August1st to 15thNight
5%10%50%32%1
539
16th to endNight
6%112%45%32%2
573
September1st to 15thNight
10%220%42%23%1
540
16th to endNight
10%230%35%19%2
537
October1st to 15thNight
11%6%29%38%13%1
513
16th to endNight
7%5%36%33%16%
738
November1st to 15thNight
6%8%36%35%11%
875
16th to endNight
8%11%37%30%11%
900
December1st to 15thNight
10%10%37%31%8%1
900
16th to endNight
14%10%35%32%7%
960
Page generated at 2017-10-07 13:07:51. Version ac04

Copyright 2017 A. Danko


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