Greeley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Greeley 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
59%
15950
25%
46811
19%
15911
64%
15911
39%
26492

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
56%
897
29%
2506
21%
895
62%
895
43%
1393
January16th to endNight
54%
843
31%
2571
23%
843
62%
843
40%
1421
February1st to 15thNight
48%
699
22%
2244
16%
698
56%
698
33%
1307
February16th to endNight
46%
632
28%
1894
17%
632
56%
632
36%
1088
March1st to 15thNight
53%
720
26%
2136
16%
720
61%
720
40%
1194
March16th to endNight
49%
666
22%
2010
15%
666
56%
666
35%
1185
April1st to 15thNight
44%
539
21%
1798
15%
539
54%
539
30%
1033
April16th to endNight
43%
540
19%
1800
17%
540
50%
540
26%
1092
May1st to 15thNight
51%
540
18%
1577
15%
540
55%
540
27%
1023
May16th to endNight
55%
561
17%
1498
13%
561
58%
561
32%
952
June1st to 15thNight
63%
540
18%
1440
13%
540
66%
540
43%
837
June16th to endNight
74%
540
26%
1440
21%
540
75%
540
53%
756
July1st to 15thNight
70%
510
17%
1360
15%
510
70%
510
38%
835
July16th to endNight
78%
564
26%
1416
22%
531
78%
531
43%
801
August1st to 15thNight
74%
539
19%
1660
19%
536
74%
536
37%
924
August16th to endNight
75%
573
27%
1910
30%
573
77%
573
38%
1007
September1st to 15thNight
65%
530
26%
1766
27%
530
70%
530
37%
945
September16th to endNight
74%
492
34%
1781
35%
492
79%
492
48%
780
October1st to 15thNight
59%
635
27%
1955
21%
635
63%
635
38%
1087
October16th to endNight
65%
755
33%
2163
22%
755
70%
755
46%
1143
November1st to 15thNight
63%
875
30%
2275
19%
875
67%
875
48%
1273
November16th to endNight
60%
900
34%
2403
22%
900
67%
900
49%
1316
December1st to 15thNight
56%
900
22%
2520
16%
900
61%
900
39%
1481
December16th to endNight
53%
960
25%
2688
17%
960
60%
960
36%
1619

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
6%42332446%8%52%
47868
Night
6%5%24423447%54%
46983
Cloud CoverDay
6%42432445%8%52%
47866
Night
6%5%2442345%7%54%
46983
TransparencyDay
28%6%12%25%20%7%
47542
Night
28%5%12%26%20%6%
46811
SeeingDay
9%5%21%32%23%7%
5876
Night
8%222%47%17%1
15960

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
37%24323248%56%
1432
16th to endDay
26%25%31445%6%57%
1665
February1st to 15thDay
37%45%5%2345%8%48%
1618
16th to endDay
36%35%32445%7%54%
1580
March1st to 15thDay
34235%25%35%7%55%
1824
16th to endDay
7%5%25%32445%8%48%
2214
April1st to 15thDay
9%5%2432336%7%50%
2150
16th to endDay
13%6%2442445%8%43%
2160
May1st to 15thDay
12%6%24425%5%6%9%41%
2369
16th to endDay
9%5%24435%5%6%9%43%
2616
June1st to 15thDay
6%4133345%6%10%50%
2520
16th to endDay
322315%6%7%9%57%
2520
July1st to 15thDay
6%313335%5%6%9%49%
2520
16th to endDay
3213425%6%7%10%50%
2656
August1st to 15thDay
4313436%6%8%10%44%
2289
16th to endDay
42123245%8%8%55%
2292
September1st to 15thDay
7%223314447%58%
2113
16th to endDay
4212423335%65%
1848
October1st to 15thDay
7%5%2322336%7%55%
1672
16th to endDay
6%413222337%63%
1697
November1st to 15thDay
26%13334447%56%
1583
16th to endDay
342332235%8%58%
1554
December1st to 15thDay
28%2442445%7%51%
1440
16th to endDay
5%6%35%433347%50%
1536
January1st to 15thNight
25%35%323346%59%
2506
16th to endNight
46%24422446%57%
2571
February1st to 15thNight
48%36%423347%51%
2234
16th to endNight
48%35%42334455%
1894
March1st to 15thNight
4425%42335%6%56%
2136
16th to endNight
7%5%34424446%51%
2010
April1st to 15thNight
8%6%245%24447%50%
1798
16th to endNight
15%7%24423336%46%
1800
May1st to 15thNight
14%5%2342445%7%44%
1576
16th to endNight
11%424325%5%5%8%47%
1497
June1st to 15thNight
6%21242445%9%55%
1440
16th to endNight
31233235%8%63%
1440
July1st to 15thNight
7%3245%2346%9%49%
1440
16th to endNight
3214335%5%7%8%55%
1512
August1st to 15thNight
43134346%6%11%49%
1668
16th to endNight
5%312425%5%5%8%55%
1910
September1st to 15thNight
8%31432345%8%53%
1766
16th to endNight
42231345%5%65%
1781
October1st to 15thNight
9%413323346%55%
1955
16th to endNight
7%413212336%62%
2163
November1st to 15thNight
4424313446%60%
2275
16th to endNight
45%23322347%61%
2403
December1st to 15thNight
46%2442345%7%53%
2520
16th to endNight
5%8%3442335%7%50%
2688

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
37%25%323338%56%
1432
16th to endDay
26%25%32445%6%56%
1665
February1st to 15thDay
37%46%43346%8%48%
1618
16th to endDay
26%36%32436%7%53%
1580
March1st to 15thDay
34245%25%45%7%54%
1824
16th to endDay
7%6%3433446%8%48%
2212
April1st to 15thDay
8%6%25%32445%7%50%
2150
16th to endDay
12%7%2442445%8%43%
2160
May1st to 15thDay
12%5%24425%46%9%41%
2369
16th to endDay
9%424435%5%6%9%43%
2616
June1st to 15thDay
7%31333446%11%50%
2520
16th to endDay
32123246%6%9%58%
2520
July1st to 15thDay
6%314435%5%6%9%49%
2520
16th to endDay
3213435%6%7%10%50%
2656
August1st to 15thDay
5%314436%6%8%11%44%
2289
16th to endDay
4213325%5%6%9%55%
2292
September1st to 15thDay
7%31321435%7%58%
2113
16th to endDay
5%23322346%65%
1848
October1st to 15thDay
8%42321345%7%55%
1672
16th to endDay
6%413212237%63%
1697
November1st to 15thDay
26%1432445%7%56%
1583
16th to endDay
342332236%8%58%
1554
December1st to 15thDay
37%35%4235%48%51%
1440
16th to endDay
5%7%35%424446%50%
1536
January1st to 15thNight
25%25%423346%59%
2506
16th to endNight
36%24422446%57%
2571
February1st to 15thNight
47%36%424346%51%
2234
16th to endNight
48%35%423345%55%
1894
March1st to 15thNight
45%25%42345%6%55%
2136
16th to endNight
7%435%424446%51%
2010
April1st to 15thNight
7%7%235%24447%50%
1798
16th to endNight
14%8%24424246%45%
1800
May1st to 15thNight
14%6%14425%45%8%44%
1576
16th to endNight
10%424335%45%8%46%
1497
June1st to 15thNight
7%21242445%9%55%
1440
16th to endNight
31232345%8%63%
1440
July1st to 15thNight
6%4235%2347%9%49%
1440
16th to endNight
3214325%5%6%9%54%
1512
August1st to 15thNight
42234346%6%10%50%
1668
16th to endNight
5%3134245%5%8%54%
1910
September1st to 15thNight
8%31442345%8%54%
1766
16th to endNight
412313445%66%
1781
October1st to 15thNight
10%413323446%56%
1955
16th to endNight
8%413222236%61%
2163
November1st to 15thNight
4324313346%60%
2275
16th to endNight
4423323346%61%
2403
December1st to 15thNight
5%6%2442345%8%52%
2520
16th to endNight
5%7%35%42435%7%50%
2688

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%412%33%19%3
1433
16th to endDay
25%412%31%20%5%
1665
February1st to 15thDay
32%6%13%32%10%3
1619
16th to endDay
28%5%9%31%21%4
1580
March1st to 15thDay
27%412%26%22%5%
1824
16th to endDay
31%5%16%24%16%4
2214
April1st to 15thDay
31%6%12%24%17%7%
2150
16th to endDay
37%7%13%22%16%3
2160
May1st to 15thDay
38%7%12%25%14%2
2369
16th to endDay
34%8%16%21%13%4
2620
June1st to 15thDay
27%7%16%19%20%7%
2520
16th to endDay
19%6%11%22%26%13%
2520
July1st to 15thDay
28%8%11%21%16%13%
2371
16th to endDay
24%8%12%24%20%8%
2489
August1st to 15thDay
28%8%15%19%15%11%
2273
16th to endDay
21%7%11%23%25%9%
2292
September1st to 15thDay
24%49%23%21%16%
2113
16th to endDay
20%46%24%35%8%
1848
October1st to 15thDay
26%5%12%21%25%7%
1672
16th to endDay
22%38%29%26%9%
1697
November1st to 15thDay
25%411%24%23%9%
1583
16th to endDay
22%310%26%28%7%
1554
December1st to 15thDay
29%6%13%33%13%2
1440
16th to endDay
32%5%15%25%17%4
1536
January1st to 15thNight
26%413%30%22%3
2506
16th to endNight
28%49%28%22%5%
2571
February1st to 15thNight
33%5%13%29%14%3
2244
16th to endNight
31%48%27%20%7%
1894
March1st to 15thNight
27%5%10%25%24%6%
2136
16th to endNight
32%5%14%23%20%4
2010
April1st to 15thNight
33%5%11%26%16%6%
1798
16th to endNight
39%412%23%16%3
1800
May1st to 15thNight
38%7%14%21%14%2
1577
16th to endNight
34%8%19%20%11%6%
1498
June1st to 15thNight
25%7%19%25%12%9%
1440
16th to endNight
18%5%12%27%25%9%
1440
July1st to 15thNight
31%6%13%23%16%9%
1360
16th to endNight
23%8%14%26%18%8%
1416
August1st to 15thNight
26%7%18%22%16%8%
1660
16th to endNight
26%6%11%25%21%9%
1910
September1st to 15thNight
27%5%12%21%18%14%
1766
16th to endNight
18%310%28%30%8%
1781
October1st to 15thNight
28%5%14%18%24%9%
1955
16th to endNight
24%39%28%24%9%
2163
November1st to 15thNight
23%410%23%26%11%
2275
16th to endNight
23%38%29%26%7%
2403
December1st to 15thNight
29%5%15%29%16%3
2520
16th to endNight
33%414%29%16%1
2688

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
8%5%13%40%22%10%
90
16th to endDay
9%319%43%16%7%
96
February1st to 15thDay
36%26%51%12%
90
16th to endDay
11%428%32%17%6%
81
March1st to 15thDay
39%21%42%17%4
114
16th to endDay
10%12%39%28%7%1
288
April1st to 15thDay
13%15%34%22%9%4
269
16th to endDay
21%16%31%20%8%2
270
May1st to 15thDay
14%7%23%30%19%4
450
16th to endDay
15%6%18%29%23%6%
517
June1st to 15thDay
7%318%34%26%8%
495
16th to endDay
4219%35%29%8%
495
July1st to 15thDay
10%114%30%31%10%
475
16th to endDay
4111%28%40%12%
515
August1st to 15thDay
6%222%34%25%8%
324
16th to endDay
6%118%33%30%9%
332
September1st to 15thDay
6%323%34%22%9%
300
16th to endDay
4317%24%31%18%
123
October1st to 15thDay
7%310%31%33%14%
90
16th to endDay
6%217%30%28%15%
96
November1st to 15thDay
2213%32%22%27%
90
16th to endDay
14%8%22%34%17%2
90
December1st to 15thDay
7%425%45%15%1
90
16th to endDay
2222%61%9%2
96
January1st to 15thNight
4327%47%13%2
900
16th to endNight
7%228%50%10%
843
February1st to 15thNight
7%329%50%9%
704
16th to endNight
8%333%47%6%
632
March1st to 15thNight
5%331%46%12%
720
16th to endNight
8%431%44%10%
666
April1st to 15thNight
11%434%43%5%
539
16th to endNight
18%5%26%36%12%
540
May1st to 15thNight
16%322%41%15%
540
16th to endNight
12%322%38%21%1
563
June1st to 15thNight
7%221%49%18%
540
16th to endNight
416%55%22%
540
July1st to 15thNight
7%11%42%35%1
510
16th to endNight
47%43%42%2
564
August1st to 15thNight
5%11%47%34%1
539
16th to endNight
6%10%44%36%1
573
September1st to 15thNight
9%115%41%27%3
530
16th to endNight
4114%49%28%1
492
October1st to 15thNight
13%220%40%20%2
635
16th to endNight
10%217%47%19%1
755
November1st to 15thNight
5%220%52%16%1
875
16th to endNight
6%224%51%13%1
900
December1st to 15thNight
8%323%54%9%
900
16th to endNight
8%323%53%10%
960
Page generated at 2017-09-13 05:39:12. Version ac04

Copyright 2017 A. Danko


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