City of Rocks National Reserve
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the City of Rocks National Reserve clear sky chart from 2005-11-05 to 2017-09-18.

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
54%
15119
20%
46918
17%
15084
58%
15084
29%
28322

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
49%
716
13%
2506
13%
716
51%
716
17%
1730
January16th to endNight
50%
768
17%
2572
17%
768
53%
768
21%
1706
February1st to 15thNight
40%
700
12%
2259
11%
698
44%
698
18%
1609
February16th to endNight
41%
632
17%
1895
15%
632
46%
632
24%
1238
March1st to 15thNight
48%
720
14%
2079
11%
720
52%
720
25%
1374
March16th to endNight
39%
768
16%
2112
10%
768
44%
768
25%
1397
April1st to 15thNight
43%
692
18%
1817
8%
692
49%
692
27%
1211
April16th to endNight
44%
540
23%
1620
13%
540
50%
540
30%
963
May1st to 15thNight
51%
539
20%
1619
14%
539
54%
539
34%
926
May16th to endNight
56%
561
16%
1685
15%
561
59%
561
29%
1037
June1st to 15thNight
61%
366
17%
1446
19%
366
68%
366
28%
765
June16th to endNight
71%
360
27%
1440
35%
360
81%
360
51%
557
July1st to 15thNight
78%
340
20%
1360
28%
340
82%
340
37%
629
July16th to endNight
75%
477
29%
1509
31%
447
77%
447
49%
679
August1st to 15thNight
71%
539
27%
1611
23%
536
73%
536
45%
829
August16th to endNight
75%
608
36%
1754
27%
608
78%
608
51%
885
September1st to 15thNight
75%
720
30%
1926
21%
720
80%
720
55%
997
September16th to endNight
72%
667
36%
1847
29%
667
76%
667
53%
942
October1st to 15thNight
60%
660
30%
1879
23%
660
66%
660
45%
1019
October16th to endNight
58%
704
25%
2205
22%
704
64%
704
34%
1246
November1st to 15thNight
51%
700
21%
2275
20%
700
55%
700
26%
1382
November16th to endNight
49%
720
19%
2340
15%
720
55%
720
25%
1444
December1st to 15thNight
40%
854
8%
2474
5%
854
42%
854
19%
1789
December16th to endNight
38%
768
12%
2688
11%
768
41%
768
13%
1968

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
47%36%5%35%5%5%7%46%
47870
Night
46%35%5%35%5%6%7%47%
47099
TransparencyDay
35%7%11%20%16%8%
47550
Night
33%7%13%21%16%7%
46919
SeeingDay
7%18%31%25%13%2
5321
Night
6%9%22%32%22%5%
15130

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
310%6%11%8%5%5%6%5%7%29%
1432
16th to endDay
5%9%5%9%8%45%6%45%35%
1650
February1st to 15thDay
310%6%10%9%46%6%5%6%30%
1604
16th to endDay
310%6%9%9%46%46%8%29%
1579
March1st to 15thDay
312%5%8%8%45%6%5%7%32%
1881
16th to endDay
6%11%5%10%7%4445%7%30%
2112
April1st to 15thDay
6%10%47%6%36%5%6%7%35%
2130
16th to endDay
6%9%37%6%3445%6%40%
2340
May1st to 15thDay
5%5%25%5%36%5%6%9%45%
2331
16th to endDay
7%8%47%7%46%5%6%7%34%
2429
June1st to 15thDay
7%5%25%5%25%5%6%8%46%
2511
16th to endDay
222212335%71%
2520
July1st to 15thDay
22133245%7%7%59%
2520
16th to endDay
2213224446%64%
2553
August1st to 15thDay
33133235%6%7%59%
2340
16th to endDay
12332445%7%64%
2446
September1st to 15thDay
23133235%47%62%
2034
16th to endDay
6%313322346%62%
1838
October1st to 15thDay
7%6%245%3436%6%49%
1749
16th to endDay
36%26%5%35%5%48%47%
1664
November1st to 15thDay
7%11%37%5%3445%5%40%
1584
16th to endDay
49%47%7%5%5%5%5%7%37%
1620
December1st to 15thDay
411%5%10%8%5%5%6%5%6%29%
1467
16th to endDay
5%12%5%13%10%5%6%5%5%6%23%
1536
January1st to 15thNight
49%47%7%36%7%6%7%34%
2506
16th to endNight
410%47%7%35%5%5%5%39%
2572
February1st to 15thNight
210%410%8%46%5%5%6%32%
2248
16th to endNight
37%5%7%6%46%46%9%38%
1895
March1st to 15thNight
26%36%7%37%6%7%8%39%
2079
16th to endNight
6%6%26%6%25%6%7%9%39%
2112
April1st to 15thNight
47%35%7%35%5%6%7%43%
1817
16th to endNight
7%425%5%35%46%7%48%
1620
May1st to 15thNight
3425%5%3445%8%51%
1619
16th to endNight
8%7%24425%5%6%8%44%
1684
June1st to 15thNight
4424445%5%5%7%51%
1446
16th to endNight
2112312246%72%
1440
July1st to 15thNight
1214425%5%6%6%59%
1440
16th to endNight
321332245%5%65%
1613
August1st to 15thNight
331343445%8%58%
1620
16th to endNight
321322345%6%63%
1754
September1st to 15thNight
2212322445%68%
1926
16th to endNight
4213213345%67%
1847
October1st to 15thNight
6%413323347%58%
1879
16th to endNight
5%415%435%5%7%7%50%
2205
November1st to 15thNight
7%6%35%5%25%5%6%6%44%
2275
16th to endNight
25%47%6%46%6%6%7%42%
2340
December1st to 15thNight
5%8%5%8%7%46%6%7%7%31%
2474
16th to endNight
7%10%410%9%5%7%6%6%5%26%
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
51%10%15%16%41
1432
16th to endDay
47%9%15%17%6%3
1650
February1st to 15thDay
48%10%13%17%7%2
1604
16th to endDay
47%10%15%21%41
1579
March1st to 15thDay
43%10%17%19%7%1
1881
16th to endDay
47%9%16%17%8%
2112
April1st to 15thDay
44%8%14%21%9%
2130
16th to endDay
42%5%12%25%13%
2340
May1st to 15thDay
33%6%9%31%17%1
2331
16th to endDay
45%6%10%24%10%1
2432
June1st to 15thDay
33%6%11%25%18%4
2511
16th to endDay
15%25%20%35%19%
2520
July1st to 15thDay
20%5%6%17%28%21%
2371
16th to endDay
18%4410%25%35%
2394
August1st to 15thDay
20%5%6%14%25%27%
2325
16th to endDay
19%46%20%29%19%
2446
September1st to 15thDay
21%48%17%27%20%
2034
16th to endDay
22%47%26%30%9%
1838
October1st to 15thDay
32%5%14%27%15%3
1749
16th to endDay
33%7%14%24%17%2
1664
November1st to 15thDay
42%6%12%24%10%3
1584
16th to endDay
42%7%18%21%7%2
1620
December1st to 15thDay
51%9%18%16%3
1467
16th to endDay
56%9%15%12%5%
1536
January1st to 15thNight
43%13%15%20%6%1
2506
16th to endNight
43%8%13%21%9%4
2572
February1st to 15thNight
45%11%13%18%9%1
2259
16th to endNight
39%8%16%26%7%1
1895
March1st to 15thNight
37%10%18%20%11%1
2079
16th to endNight
36%10%19%24%8%1
2112
April1st to 15thNight
38%7%15%25%10%2
1817
16th to endNight
33%5%13%27%18%
1620
May1st to 15thNight
30%5%13%26%20%3
1620
16th to endNight
35%6%12%29%14%1
1685
June1st to 15thNight
29%7%12%22%23%4
1446
16th to endNight
15%37%17%34%21%
1440
July1st to 15thNight
22%5%6%15%28%20%
1360
16th to endNight
19%3413%24%35%
1509
August1st to 15thNight
23%45%15%26%25%
1611
16th to endNight
20%4418%30%22%
1754
September1st to 15thNight
18%47%16%29%22%
1926
16th to endNight
19%38%23%31%14%
1847
October1st to 15thNight
25%313%30%21%5%
1879
16th to endNight
28%6%12%29%17%4
2205
November1st to 15thNight
34%8%14%21%15%5%
2275
16th to endNight
33%11%16%25%11%1
2340
December1st to 15thNight
44%12%20%16%5%
2474
16th to endNight
53%8%14%15%6%
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%18%31%21%15%5%
60
16th to endDay
8%18%24%31%18%
83
February1st to 15thDay
7%21%28%17%21%2
119
16th to endDay
10%29%32%20%7%
238
March1st to 15thDay
5%26%37%21%8%
270
16th to endDay
13%36%31%14%3
288
April1st to 15thDay
11%28%30%17%9%2
269
16th to endDay
13%33%29%16%5%
270
May1st to 15thDay
8%25%34%21%9%1
288
16th to endDay
12%15%32%21%14%3
330
June1st to 15thDay
7%18%30%28%12%2
315
16th to endDay
215%35%26%15%3
315
July1st to 15thDay
37%31%39%16%2
305
16th to endDay
28%37%33%13%3
327
August1st to 15thDay
5%7%36%35%13%
315
16th to endDay
25%30%30%24%6%
332
September1st to 15thDay
411%23%30%20%9%
315
16th to endDay
7%9%27%30%20%4
264
October1st to 15thDay
7%18%25%27%17%2
189
16th to endDay
9%13%37%29%7%3
96
November1st to 15thDay
10%6%22%24%30%6%
90
16th to endDay
14%27%30%22%41
90
December1st to 15thDay
8%23%49%15%2
89
16th to endDay
420%26%29%17%1
64
January1st to 15thNight
7%12%22%31%21%4
720
16th to endNight
8%13%21%27%23%5%
768
February1st to 15thNight
7%13%25%29%20%2
704
16th to endNight
6%13%30%30%16%3
632
March1st to 15thNight
412%28%34%16%3
720
16th to endNight
8%16%28%30%14%1
768
April1st to 15thNight
8%14%26%31%15%3
692
16th to endNight
9%13%27%30%16%2
540
May1st to 15thNight
412%27%29%21%3
540
16th to endNight
11%7%16%29%28%5%
563
June1st to 15thNight
48%18%39%24%3
366
16th to endNight
3317%39%31%5%
360
July1st to 15thNight
1111%39%40%5%
340
16th to endNight
2112%42%34%6%
477
August1st to 15thNight
5%213%46%28%3
539
16th to endNight
4212%40%35%4
608
September1st to 15thNight
4114%30%36%12%
720
16th to endNight
6%314%30%29%15%
667
October1st to 15thNight
9%421%31%25%7%
660
16th to endNight
5%7%22%31%26%6%
704
November1st to 15thNight
9%10%22%30%22%5%
700
16th to endNight
414%25%32%16%6%
720
December1st to 15thNight
8%13%29%31%14%1
854
16th to endNight
11%14%25%33%11%2
768
Page generated at 2017-09-19 05:32:20. Version ac04

Copyright 2017 A. Danko


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