Courtright Reservoir
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Courtright Reservoir clear sky chart from 2005-11-05 to 2017-10-31.

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
66%
15586
30%
47363
26%
15554
71%
15554
46%
24154

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
52%
716
25%
2506
20%
716
61%
716
36%
1320
January16th to endNight
50%
768
27%
2510
23%
768
59%
768
32%
1421
February1st to 15thNight
54%
700
29%
2132
25%
697
61%
697
35%
1224
February16th to endNight
50%
632
24%
1895
22%
632
56%
632
31%
1162
March1st to 15thNight
56%
720
22%
2160
21%
720
61%
720
36%
1258
March16th to endNight
55%
768
22%
1989
14%
768
60%
768
38%
1208
April1st to 15thNight
54%
719
22%
1799
11%
719
58%
719
38%
1110
April16th to endNight
59%
720
23%
1800
11%
720
62%
720
46%
1030
May1st to 15thNight
67%
592
28%
1672
19%
592
70%
592
51%
844
May16th to endNight
64%
461
27%
1585
25%
461
68%
461
44%
749
June1st to 15thNight
78%
360
29%
1440
35%
360
84%
360
48%
582
June16th to endNight
92%
360
39%
1440
50%
360
94%
360
75%
445
July1st to 15thNight
92%
340
34%
1360
44%
340
92%
340
64%
468
July16th to endNight
88%
429
36%
1465
40%
403
88%
403
55%
595
August1st to 15thNight
90%
705
37%
1779
24%
702
91%
702
78%
808
August16th to endNight
91%
764
43%
1910
29%
764
91%
764
75%
894
September1st to 15thNight
90%
720
42%
1800
31%
720
90%
720
76%
838
September16th to endNight
81%
716
44%
1972
37%
716
86%
716
70%
874
October1st to 15thNight
71%
720
34%
2073
31%
720
77%
720
58%
969
October16th to endNight
74%
768
40%
2340
39%
768
80%
768
54%
1097
November1st to 15thNight
69%
700
32%
2275
32%
700
75%
700
46%
1114
November16th to endNight
61%
720
30%
2340
28%
720
67%
720
41%
1200
December1st to 15thNight
53%
720
23%
2433
19%
720
62%
720
32%
1363
December16th to endNight
43%
768
25%
2688
19%
768
53%
768
26%
1581

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
5%6%23313335%60%
48388
Night
45%23212335%63%
47548
TransparencyDay
25%49%21%24%13%
48064
Night
23%39%23%26%13%
47372
SeeingDay
10%13%33%27%11%3
5987
Night
8%316%34%31%5%
15597

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
9%8%23412446%51%
1432
16th to endDay
8%10%35%323347%47%
1713
February1st to 15thDay
6%10%36%313246%50%
1721
16th to endDay
9%12%6%8%423325%43%
1579
March1st to 15thDay
412%5%6%32345%7%44%
1800
16th to endDay
7%13%46%424347%42%
2230
April1st to 15thDay
7%9%6%6%323336%46%
2149
16th to endDay
8%10%2221435%6%52%
2160
May1st to 15thDay
48%12223246%59%
2277
16th to endDay
6%9%22313446%54%
2526
June1st to 15thDay
4412313336%64%
2520
16th to endDay
21111112382%
2520
July1st to 15thDay
2112212345%71%
2520
16th to endDay
321231234470%
2601
August1st to 15thDay
11121222480%
2172
16th to endDay
2111211335%75%
2292
September1st to 15thDay
32121232474%
2160
16th to endDay
23122223472%
1986
October1st to 15thDay
45%2222224466%
1884
16th to endDay
5%31322233466%
1882
November1st to 15thDay
5%6%24314235%58%
1584
16th to endDay
5%6%13412247%58%
1620
December1st to 15thDay
9%9%34323336%51%
1524
16th to endDay
9%8%5%6%323236%49%
1536
January1st to 15thNight
8%7%22313346%55%
2506
16th to endNight
7%9%33213446%52%
2510
February1st to 15thNight
7%9%34313247%51%
2129
16th to endNight
8%10%46%223336%48%
1895
March1st to 15thNight
49%36%323346%52%
2160
16th to endNight
310%4422345%7%52%
1989
April1st to 15thNight
6%9%34323447%51%
1799
16th to endNight
46%2331245%5%61%
1800
May1st to 15thNight
2412313335%67%
1672
16th to endNight
37%12312225%66%
1584
June1st to 15thNight
333212337%69%
1440
16th to endNight
1112287%
1440
July1st to 15thNight
11121113379%
1440
16th to endNight
221211322375%
1565
August1st to 15thNight
1111111285%
1788
16th to endNight
1111111283%
1910
September1st to 15thNight
1111123383%
1800
16th to endNight
11111122379%
1972
October1st to 15thNight
3311112335%72%
2073
16th to endNight
5%21221223471%
2340
November1st to 15thNight
5%5%12213246%65%
2275
16th to endNight
45%34323347%57%
2340
December1st to 15thNight
8%8%24323346%51%
2433
16th to endNight
11%9%25%323436%47%
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
32%410%23%19%9%
1432
16th to endDay
38%5%8%20%14%13%
1713
February1st to 15thDay
34%311%24%16%8%
1721
16th to endDay
44%49%20%16%2
1579
March1st to 15thDay
38%6%12%18%17%6%
1800
16th to endDay
41%7%16%20%12%2
2230
April1st to 15thDay
40%5%13%23%15%2
2149
16th to endDay
32%6%16%25%15%2
2160
May1st to 15thDay
25%5%12%35%18%2
2277
16th to endDay
29%6%13%27%19%2
2529
June1st to 15thDay
21%5%12%24%25%10%
2520
16th to endDay
9%2319%43%21%
2520
July1st to 15thDay
13%45%10%31%33%
2371
16th to endDay
15%48%14%27%31%
2438
August1st to 15thDay
9%3413%35%33%
2157
16th to endDay
11%35%15%41%22%
2292
September1st to 15thDay
11%48%14%34%26%
2160
16th to endDay
14%37%28%30%15%
1986
October1st to 15thDay
21%28%21%29%16%
1884
16th to endDay
20%37%25%28%15%
1882
November1st to 15thDay
27%410%24%22%9%
1584
16th to endDay
26%310%21%31%6%
1620
December1st to 15thDay
36%49%23%20%6%
1524
16th to endDay
38%412%19%14%10%
1536
January1st to 15thNight
28%48%24%23%9%
2506
16th to endNight
32%49%17%19%15%
2510
February1st to 15thNight
32%47%27%19%9%
2140
16th to endNight
37%410%22%21%3
1895
March1st to 15thNight
32%412%21%20%9%
2160
16th to endNight
30%5%16%25%18%3
1989
April1st to 15thNight
32%414%27%16%4
1799
16th to endNight
23%6%17%31%16%5%
1800
May1st to 15thNight
19%413%35%23%3
1673
16th to endNight
21%413%31%25%3
1585
June1st to 15thNight
15%413%26%31%9%
1440
16th to endNight
5%25%17%44%24%
1440
July1st to 15thNight
9%2314%35%33%
1360
16th to endNight
14%35%14%29%31%
1465
August1st to 15thNight
8%1317%34%34%
1779
16th to endNight
9%1318%43%23%
1910
September1st to 15thNight
8%2416%41%26%
1800
16th to endNight
10%26%29%34%16%
1972
October1st to 15thNight
14%37%24%31%16%
2073
16th to endNight
17%35%24%33%15%
2340
November1st to 15thNight
22%310%25%25%12%
2275
16th to endNight
26%39%21%28%10%
2340
December1st to 15thNight
32%413%20%22%6%
2433
16th to endNight
37%49%18%16%13%
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
43%10%20%15%8%3
60
16th to endDay
19%14%23%25%13%2
241
February1st to 15thDay
16%13%26%23%16%3
261
16th to endDay
18%22%31%19%7%
238
March1st to 15thDay
13%22%30%19%11%3
270
16th to endDay
19%19%34%20%6%
288
April1st to 15thDay
17%23%31%22%4
269
16th to endDay
16%21%37%19%5%
270
May1st to 15thDay
14%15%29%25%11%3
288
16th to endDay
18%12%25%25%13%4
330
June1st to 15thDay
8%11%36%26%12%4
315
16th to endDay
111%26%35%18%5%
315
July1st to 15thDay
3435%31%16%8%
305
16th to endDay
36%33%36%13%5%
327
August1st to 15thDay
210%47%25%9%4
315
16th to endDay
2337%35%15%4
332
September1st to 15thDay
48%40%35%8%1
315
16th to endDay
5%13%40%30%9%
315
October1st to 15thDay
6%19%38%28%6%
315
16th to endDay
10%13%31%31%12%2
300
November1st to 15thDay
7%7%13%23%34%13%
90
16th to endDay
6%17%28%34%10%2
90
December1st to 15thDay
16%9%33%25%14%
74
16th to endDay
15%10%23%25%20%4
64
January1st to 15thNight
12%326%26%24%6%
720
16th to endNight
13%7%23%31%17%5%
768
February1st to 15thNight
13%222%35%21%3
704
16th to endNight
16%5%23%33%17%3
632
March1st to 15thNight
10%6%21%35%21%4
720
16th to endNight
11%5%22%35%23%1
768
April1st to 15thNight
10%5%22%38%19%2
719
16th to endNight
9%5%21%35%23%4
720
May1st to 15thNight
5%317%41%27%4
593
16th to endNight
8%317%28%36%4
463
June1st to 15thNight
3110%38%42%3
360
16th to endNight
442%46%6%
360
July1st to 15thNight
1127%63%6%
340
16th to endNight
21124%61%9%
429
August1st to 15thNight
15%35%55%3
705
16th to endNight
1230%58%6%
764
September1st to 15thNight
1435%49%7%
720
16th to endNight
2210%33%41%9%
716
October1st to 15thNight
5%217%37%29%7%
720
16th to endNight
5%312%33%32%11%
768
November1st to 15thNight
7%214%37%29%7%
700
16th to endNight
7%423%36%23%5%
720
December1st to 15thNight
13%5%22%37%16%4
720
16th to endNight
17%8%25%31%15%2
768
Page generated at 2017-11-01 14:23:37. Version ac04

Copyright 2017 A. Danko


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