Natural Bridges National Monument
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Natural Bridges National Monument clear sky chart from 2005-11-05 to 2017-08-12.

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
63%
15520
29%
46793
24%
15480
69%
15480
42%
24767

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
65%
718
27%
2327
28%
716
70%
716
40%
1203
January16th to endNight
58%
768
32%
2496
30%
768
65%
768
35%
1360
February1st to 15thNight
61%
700
26%
2288
24%
700
68%
700
40%
1176
February16th to endNight
51%
632
31%
1896
24%
632
61%
632
37%
1044
March1st to 15thNight
57%
720
32%
1980
23%
720
64%
720
43%
1092
March16th to endNight
54%
768
29%
2112
19%
768
62%
768
39%
1218
April1st to 15thNight
45%
609
25%
1868
14%
609
56%
609
32%
1047
April16th to endNight
47%
540
32%
1725
20%
540
61%
540
39%
859
May1st to 15thNight
54%
539
27%
1619
20%
539
60%
539
40%
861
May16th to endNight
57%
563
27%
1685
19%
561
66%
561
47%
847
June1st to 15thNight
66%
540
27%
1620
22%
540
72%
540
54%
753
June16th to endNight
77%
540
32%
1620
29%
540
81%
540
65%
695
July1st to 15thNight
71%
510
17%
1530
14%
510
73%
510
36%
882
July16th to endNight
74%
564
21%
1593
18%
531
74%
531
31%
968
August1st to 15thNight
77%
527
24%
1575
22%
524
77%
524
39%
878
August16th to endNight
79%
525
30%
1668
29%
525
81%
525
43%
869
September1st to 15thNight
72%
564
29%
1719
28%
564
74%
564
38%
951
September16th to endNight
74%
656
39%
1815
28%
656
81%
656
59%
879
October1st to 15thNight
64%
660
33%
1965
24%
660
69%
660
48%
980
October16th to endNight
68%
704
38%
2112
30%
704
76%
704
52%
1010
November1st to 15thNight
66%
700
33%
2139
28%
700
71%
700
45%
1072
November16th to endNight
65%
772
35%
2392
30%
772
72%
772
46%
1165
December1st to 15thNight
59%
900
25%
2520
19%
900
63%
900
40%
1447
December16th to endNight
55%
801
24%
2529
21%
801
60%
801
30%
1511

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%5%2442445%6%55%
47169
Night
5%5%24423446%57%
46988
TransparencyDay
25%49%20%25%15%
46864
Night
25%48%20%25%15%
46794
SeeingDay
8%9%26%33%18%3
5085
Night
6%5%16%35%29%7%
15527

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%9%23323346%55%
1611
16th to endDay
5%8%2432434456%
1728
February1st to 15thDay
48%2443335%8%53%
1575
16th to endDay
7%8%25%42445%5%50%
1575
March1st to 15thDay
5%7%34423335%57%
1980
16th to endDay
5%5%24325%5%6%6%52%
2112
April1st to 15thDay
6%5%35%42335%6%53%
2078
16th to endDay
3414424447%57%
2233
May1st to 15thDay
4425%41445%7%53%
2331
16th to endDay
5%31332445%7%57%
2429
June1st to 15thDay
3312213236%67%
2340
16th to endDay
21221233475%
2340
July1st to 15thDay
5%3245%35%5%6%8%48%
2340
16th to endDay
6%5%26%6%47%6%7%10%36%
2467
August1st to 15thDay
5%425%5%36%6%7%7%44%
2290
16th to endDay
5%4145%35%5%6%7%50%
2181
September1st to 15thDay
44145%26%5%6%6%52%
1910
16th to endDay
421213345%68%
1815
October1st to 15thDay
7%323313445%60%
1664
16th to endDay
3312222335%67%
1760
November1st to 15thDay
5%41321324466%
1717
16th to endDay
5%5%12312235%65%
1551
December1st to 15thDay
7%8%34423335%52%
1440
16th to endDay
9%9%343245%5%6%45%
1702
January1st to 15thNight
6%6%23213335%60%
2327
16th to endNight
8%7%25%32233456%
2496
February1st to 15thNight
37%24323345%59%
2277
16th to endNight
5%7%24433345%55%
1896
March1st to 15thNight
45%2442335%6%56%
1980
16th to endNight
5%5%245%3445%6%52%
2112
April1st to 15thNight
5%5%25%5%34445%53%
1868
16th to endNight
4413423446%58%
1725
May1st to 15thNight
5%42433345%8%54%
1619
16th to endNight
3323423447%61%
1684
June1st to 15thNight
4213213236%68%
1620
16th to endNight
121221323474%
1620
July1st to 15thNight
3325%5%46%6%7%10%44%
1620
16th to endNight
46%35%5%35%7%8%11%36%
1701
August1st to 15thNight
44134347%7%7%50%
1584
16th to endNight
43133345%9%8%51%
1668
September1st to 15thNight
6%313425%5%6%454%
1719
16th to endNight
421221223472%
1815
October1st to 15thNight
5%21341334464%
1965
16th to endNight
3312213345%68%
2112
November1st to 15thNight
242442333462%
2139
16th to endNight
5%31332333465%
2392
December1st to 15thNight
7%8%13423336%54%
2520
16th to endNight
9%10%34424346%47%
2529

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
29%418%33%14%1
1612
16th to endDay
28%6%12%29%21%2
1728
February1st to 15thDay
29%418%23%20%4
1575
16th to endDay
32%46%23%27%4
1575
March1st to 15thDay
26%35%30%27%6%
1980
16th to endDay
26%47%26%28%6%
2112
April1st to 15thDay
29%35%19%28%13%
2078
16th to endDay
21%46%21%30%15%
2233
May1st to 15thDay
25%46%16%34%12%
2331
16th to endDay
22%46%16%32%17%
2432
June1st to 15thDay
17%248%27%40%
2340
16th to endDay
11%126%22%53%
2340
July1st to 15thDay
27%5%10%14%14%26%
2201
16th to endDay
35%8%13%16%14%12%
2312
August1st to 15thDay
32%7%10%14%15%19%
2275
16th to endDay
27%5%9%19%20%17%
2181
September1st to 15thDay
28%5%8%14%19%23%
1910
16th to endDay
16%36%14%32%26%
1815
October1st to 15thDay
22%4420%35%12%
1664
16th to endDay
17%27%22%38%11%
1760
November1st to 15thDay
20%28%22%37%9%
1717
16th to endDay
21%28%31%31%5%
1551
December1st to 15thDay
34%414%30%15%
1440
16th to endDay
36%7%20%21%12%1
1702
January1st to 15thNight
26%312%31%22%2
2327
16th to endNight
30%37%28%25%5%
2496
February1st to 15thNight
25%414%27%19%8%
2288
16th to endNight
28%46%22%32%5%
1896
March1st to 15thNight
25%35%27%29%7%
1980
16th to endNight
28%46%21%30%8%
2112
April1st to 15thNight
30%45%17%25%16%
1868
16th to endNight
24%3420%31%15%
1725
May1st to 15thNight
25%47%16%31%14%
1620
16th to endNight
21%37%16%32%17%
1685
June1st to 15thNight
17%238%28%40%
1620
16th to endNight
12%227%18%56%
1620
July1st to 15thNight
30%6%12%11%12%26%
1530
16th to endNight
33%7%13%17%15%12%
1593
August1st to 15thNight
25%8%10%17%18%20%
1575
16th to endNight
23%5%10%18%20%21%
1668
September1st to 15thNight
28%5%8%13%17%27%
1719
16th to endNight
16%2415%29%30%
1815
October1st to 15thNight
20%46%19%27%21%
1965
16th to endNight
18%35%16%39%18%
2112
November1st to 15thNight
22%37%21%31%12%
2139
16th to endNight
20%36%24%34%10%
2392
December1st to 15thNight
29%410%30%22%2
2520
16th to endNight
36%414%26%16%1
2529

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%6%21%23%13%5%
90
16th to endDay
9%415%36%28%6%
96
February1st to 15thDay
8%411%38%33%3
90
16th to endDay
12%16%29%30%9%1
188
March1st to 15thDay
10%12%31%31%11%1
270
16th to endDay
11%16%38%23%9%
288
April1st to 15thDay
12%18%33%21%10%4
269
16th to endDay
12%25%37%17%6%1
270
May1st to 15thDay
7%18%32%29%11%
288
16th to endDay
8%13%32%25%17%3
330
June1st to 15thDay
6%11%27%35%16%2
315
16th to endDay
3325%44%20%2
315
July1st to 15thDay
5%218%42%28%2
305
16th to endDay
6%13%36%35%7%
327
August1st to 15thDay
9%115%43%24%6%
300
16th to endDay
5%119%38%30%4
268
September1st to 15thDay
6%127%44%14%4
255
16th to endDay
6%7%24%34%20%5%
255
October1st to 15thDay
5%5%24%34%25%4
104
16th to endDay
12%7%32%30%16%1
96
November1st to 15thDay
3426%31%33%1
90
16th to endDay
8%13%36%32%8%
90
December1st to 15thDay
7%333%42%13%
90
16th to endDay
19%9%13%38%15%3
96
January1st to 15thNight
6%5%13%40%27%5%
720
16th to endNight
10%416%34%27%6%
768
February1st to 15thNight
6%318%41%23%5%
704
16th to endNight
8%7%24%38%17%3
632
March1st to 15thNight
6%5%22%34%27%3
720
16th to endNight
5%8%21%35%24%4
768
April1st to 15thNight
8%13%24%33%17%3
609
16th to endNight
5%13%27%29%18%5%
540
May1st to 15thNight
6%6%25%39%17%5%
540
16th to endNight
45%25%33%23%6%
563
June1st to 15thNight
4418%38%28%5%
540
16th to endNight
2113%38%37%6%
540
July1st to 15thNight
419%32%43%8%
510
16th to endNight
5%426%52%9%
564
August1st to 15thNight
6%5%30%44%12%
527
16th to endNight
6%432%42%13%
525
September1st to 15thNight
8%19%37%34%8%
564
16th to endNight
4213%28%34%17%
656
October1st to 15thNight
6%317%35%27%9%
660
16th to endNight
5%5%15%31%30%11%
704
November1st to 15thNight
4413%37%31%8%
700
16th to endNight
6%8%13%34%29%8%
772
December1st to 15thNight
10%417%40%23%4
900
16th to endNight
13%5%14%39%25%2
801
Page generated at 2017-08-13 12:16:58. Version ac04

Copyright 2017 A. Danko


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