Cherry Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cherry Road clear sky chart from 2005-11-05 to 2017-04-08.

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
75%
15131
36%
45413
31%
15092
80%
15092
54%
21449

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
68%
719
33%
2327
30%
716
76%
716
47%
1121
January16th to endNight
64%
768
36%
2496
35%
768
72%
768
43%
1270
February1st to 15thNight
69%
698
35%
2189
30%
698
80%
698
51%
1028
February16th to endNight
67%
632
37%
1895
36%
632
74%
632
50%
951
March1st to 15thNight
68%
720
39%
1986
32%
720
76%
720
56%
987
March16th to endNight
73%
768
37%
2112
29%
768
79%
768
60%
999
April1st to 15thNight
64%
680
32%
1890
20%
680
73%
680
56%
931
April16th to endNight
67%
495
42%
1524
31%
495
77%
495
71%
598
May1st to 15thNight
73%
494
39%
1484
31%
494
78%
494
63%
631
May16th to endNight
76%
513
36%
1540
29%
513
79%
513
68%
637
June1st to 15thNight
82%
495
35%
1485
32%
495
83%
495
72%
604
June16th to endNight
86%
495
32%
1485
30%
495
87%
495
71%
607
July1st to 15thNight
85%
465
24%
1395
21%
465
85%
465
46%
717
July16th to endNight
83%
522
25%
1467
21%
489
84%
489
41%
789
August1st to 15thNight
87%
494
31%
1476
27%
491
87%
491
48%
742
August16th to endNight
87%
585
31%
1690
28%
585
87%
585
46%
907
September1st to 15thNight
82%
660
32%
1815
27%
660
84%
660
51%
958
September16th to endNight
85%
656
42%
1815
33%
656
89%
656
69%
812
October1st to 15thNight
77%
660
40%
1888
33%
660
82%
660
62%
859
October16th to endNight
81%
704
42%
2112
38%
704
86%
704
65%
917
November1st to 15thNight
78%
700
39%
2166
35%
700
84%
700
61%
951
November16th to endNight
73%
720
40%
2340
38%
720
80%
720
57%
1014
December1st to 15thNight
72%
720
36%
2340
35%
720
77%
720
48%
1110
December16th to endNight
62%
768
33%
2496
31%
768
68%
768
39%
1309

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
331332335%6%64%
45840
Night
3212223346%67%
45610
TransparencyDay
19%25%16%28%26%
45535
Night
18%25%15%29%28%
45416
SeeingDay
6%9%25%33%19%5%
4812
Night
4212%38%36%5%
15141

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%412422335%65%
1611
16th to endDay
7%5%13113346%61%
1728
February1st to 15thDay
35%24223345%62%
1670
16th to endDay
5%424423346%58%
1579
March1st to 15thDay
3323213346%65%
1974
16th to endDay
321231335%6%65%
2112
April1st to 15thDay
2213323337%66%
1894
16th to endDay
1212212245%72%
2104
May1st to 15thDay
2212224236%69%
2136
16th to endDay
2212213335%70%
2221
June1st to 15thDay
111223480%
2145
16th to endDay
1111123480%
2145
July1st to 15thDay
2212446%6%8%9%50%
2145
16th to endDay
4335%6%47%8%9%10%35%
2285
August1st to 15thDay
4215%5%35%5%8%9%48%
2145
16th to endDay
43144346%8%8%50%
2157
September1st to 15thDay
43144235%5%8%56%
1815
16th to endDay
211112236%76%
1815
October1st to 15thDay
21222344471%
1741
16th to endDay
112212236%75%
1760
November1st to 15thDay
1211213346%71%
1690
16th to endDay
5%212112235%72%
1620
December1st to 15thDay
5%5%13323336%61%
1620
16th to endDay
7%6%32422348%53%
1728
January1st to 15thNight
4323324345%63%
2327
16th to endNight
6%41332333462%
2496
February1st to 15thNight
3312322336%68%
2179
16th to endNight
6%312224347%61%
1895
March1st to 15thNight
3312312346%67%
1986
16th to endNight
2212212247%70%
2112
April1st to 15thNight
4212323336%66%
1890
16th to endNight
1112225%79%
1524
May1st to 15thNight
112212345%73%
1484
16th to endNight
12122112478%
1540
June1st to 15thNight
11111223380%
1485
16th to endNight
112212382%
1485
July1st to 15thNight
113425%6%6%8%57%
1485
16th to endNight
1314437%6%9%11%45%
1575
August1st to 15thNight
12123345%7%12%56%
1485
16th to endNight
2112336%6%6%10%54%
1690
September1st to 15thNight
231342447%7%59%
1815
16th to endNight
211111225%78%
1815
October1st to 15thNight
212212345%72%
1888
16th to endNight
112222235%75%
2112
November1st to 15thNight
2212212346%70%
2166
16th to endNight
422212235%72%
2340
December1st to 15thNight
5%312113436%64%
2340
16th to endNight
8%413423446%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
22%2417%34%18%
1612
16th to endDay
24%16%18%32%16%
1728
February1st to 15thDay
23%26%19%26%22%
1670
16th to endDay
27%1420%29%16%
1579
March1st to 15thDay
20%1216%36%22%
1974
16th to endDay
18%1418%38%18%
2112
April1st to 15thDay
18%1318%33%24%
1894
16th to endDay
15%1212%35%31%
2104
May1st to 15thDay
14%1414%32%32%
2136
16th to endDay
15%15%10%33%33%
2224
June1st to 15thDay
9%16%25%56%
2145
16th to endDay
9%12321%61%
2145
July1st to 15thDay
24%6%10%15%16%26%
2006
16th to endDay
33%7%15%20%16%6%
2130
August1st to 15thDay
26%5%9%18%19%20%
2130
16th to endDay
25%6%10%20%23%14%
2157
September1st to 15thDay
23%48%17%22%23%
1815
16th to endDay
11%1211%35%38%
1815
October1st to 15thDay
14%2415%28%34%
1741
16th to endDay
12%1414%34%32%
1760
November1st to 15thDay
14%2418%35%25%
1690
16th to endDay
16%1218%29%31%
1620
December1st to 15thDay
25%28%22%26%13%
1620
16th to endDay
29%28%23%26%9%
1728
January1st to 15thNight
23%2418%33%18%
2327
16th to endNight
26%2417%30%18%
2496
February1st to 15thNight
19%26%19%27%24%
2190
16th to endNight
22%25%18%32%18%
1895
March1st to 15thNight
18%2313%35%26%
1986
16th to endNight
15%26%16%35%23%
2112
April1st to 15thNight
19%1414%34%26%
1890
16th to endNight
8%1312%36%37%
1524
May1st to 15thNight
12%1312%31%37%
1485
16th to endNight
11%49%34%39%
1541
June1st to 15thNight
10%15%20%61%
1485
16th to endNight
10%11413%69%
1485
July1st to 15thNight
21%5%11%12%20%28%
1395
16th to endNight
24%6%14%23%20%10%
1467
August1st to 15thNight
19%6%11%18%20%23%
1476
16th to endNight
22%5%9%20%23%17%
1690
September1st to 15thNight
20%412%18%19%24%
1815
16th to endNight
10%218%37%38%
1815
October1st to 15thNight
14%1316%28%35%
1888
16th to endNight
13%15%11%25%42%
2112
November1st to 15thNight
14%1315%36%27%
2166
16th to endNight
16%2314%29%33%
2340
December1st to 15thNight
21%26%21%28%19%
2340
16th to endNight
29%28%20%30%9%
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
30%417%30%16%1
90
16th to endDay
12%5%21%30%20%9%
96
February1st to 15thDay
5%8%29%38%13%5%
185
16th to endDay
11%22%28%23%11%1
238
March1st to 15thDay
6%16%28%26%15%5%
270
16th to endDay
5%19%31%24%14%3
288
April1st to 15thDay
10%20%34%23%7%5%
239
16th to endDay
8%24%39%19%6%1
210
May1st to 15thDay
5%15%39%26%10%2
228
16th to endDay
5%12%36%29%12%3
266
June1st to 15thDay
312%37%30%13%3
255
16th to endDay
2222%48%18%6%
255
July1st to 15thDay
3123%48%20%3
245
16th to endDay
5%18%45%27%12%
271
August1st to 15thDay
314%45%25%9%
255
16th to endDay
5%9%45%29%8%
268
September1st to 15thDay
7%221%38%26%3
255
16th to endDay
8%7%19%39%21%3
255
October1st to 15thDay
39%32%26%19%8%
181
16th to endDay
4414%26%38%12%
96
November1st to 15thDay
36%12%26%34%16%
90
16th to endDay
6%8%24%33%24%2
90
December1st to 15thDay
5%413%33%43%
90
16th to endDay
18%7%19%31%20%2
96
January1st to 15thNight
6%215%46%23%5%
720
16th to endNight
8%317%41%27%1
768
February1st to 15thNight
5%217%45%27%2
704
16th to endNight
7%318%49%19%1
632
March1st to 15thNight
5%318%43%26%3
720
16th to endNight
3415%46%28%2
768
April1st to 15thNight
5%420%42%24%2
680
16th to endNight
1424%39%26%3
495
May1st to 15thNight
2315%42%32%3
495
16th to endNight
2213%40%36%4
515
June1st to 15thNight
1111%44%37%3
495
16th to endNight
26%33%49%6%
495
July1st to 15thNight
2423%59%10%
465
16th to endNight
3313%60%19%
522
August1st to 15thNight
2217%63%13%
494
16th to endNight
2116%61%16%
585
September1st to 15thNight
45%25%55%10%
660
16th to endNight
28%35%45%6%
656
October1st to 15thNight
3211%41%36%3
660
16th to endNight
1110%38%41%6%
704
November1st to 15thNight
3111%45%33%5%
700
16th to endNight
5%215%39%31%5%
720
December1st to 15thNight
9%212%43%30%1
720
16th to endNight
11%216%44%22%3
768
Page generated at 2017-04-09 03:54:17. Version ac04

Copyright 2017 A. Danko


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