Zion Lodge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Zion Lodge clear sky chart from 2005-11-05 to 2017-09-17.

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
70%
15652
32%
46926
28%
15615
75%
15615
49%
23438

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
67%
716
30%
2327
30%
716
72%
716
44%
1160
January16th to endNight
66%
768
32%
2496
31%
768
72%
768
38%
1328
February1st to 15thNight
67%
697
28%
2202
28%
697
73%
697
42%
1151
February16th to endNight
56%
632
30%
1895
28%
632
62%
632
37%
1088
March1st to 15thNight
61%
720
33%
2034
27%
720
68%
720
47%
1067
March16th to endNight
64%
768
31%
2112
23%
768
70%
768
47%
1119
April1st to 15thNight
55%
713
26%
1922
14%
713
63%
713
45%
1052
April16th to endNight
56%
540
37%
1620
23%
540
67%
540
50%
767
May1st to 15thNight
65%
539
32%
1619
25%
539
68%
539
51%
773
May16th to endNight
65%
562
29%
1685
23%
561
70%
561
49%
815
June1st to 15thNight
74%
540
30%
1620
27%
540
76%
540
65%
685
June16th to endNight
81%
540
33%
1620
32%
540
82%
540
73%
648
July1st to 15thNight
85%
510
24%
1530
23%
510
85%
510
51%
761
July16th to endNight
78%
564
24%
1593
22%
531
79%
531
39%
888
August1st to 15thNight
83%
539
31%
1611
26%
536
83%
536
52%
777
August16th to endNight
85%
648
39%
1797
32%
648
86%
648
55%
913
September1st to 15thNight
83%
720
32%
1980
27%
720
84%
720
55%
1014
September16th to endNight
81%
664
42%
1837
34%
664
86%
664
71%
798
October1st to 15thNight
74%
660
37%
1874
30%
660
78%
660
53%
944
October16th to endNight
73%
704
39%
2112
32%
704
80%
704
59%
964
November1st to 15thNight
75%
700
34%
2264
32%
700
80%
700
52%
1033
November16th to endNight
72%
720
37%
2340
36%
720
77%
720
49%
1096
December1st to 15thNight
69%
720
31%
2340
29%
720
74%
720
42%
1196
December16th to endNight
60%
768
28%
2496
26%
768
65%
768
34%
1401

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
4313323446%61%
47846
Night
5%312323346%63%
47121
TransparencyDay
21%37%18%25%21%
47541
Night
21%37%19%27%20%
46927
SeeingDay
8%11%29%32%14%3
5454
Night
7%214%37%31%6%
15665

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
7%413212445%61%
1611
16th to endDay
9%6%13322445%57%
1728
February1st to 15thDay
45%133235%5%6%58%
1659
16th to endDay
10%8%14312346%53%
1579
March1st to 15thDay
45%12312346%62%
1926
16th to endDay
6%41321446%8%54%
2112
April1st to 15thDay
6%5%23313348%57%
2020
16th to endDay
4213323335%65%
2340
May1st to 15thDay
33133235%5%7%60%
2331
16th to endDay
421331336%6%62%
2429
June1st to 15thDay
111121333475%
2340
16th to endDay
1111133479%
2340
July1st to 15thDay
321442446%7%57%
2340
16th to endDay
5%4245%36%6%7%9%44%
2467
August1st to 15thDay
32134345%5%6%58%
2340
16th to endDay
3232245%5%7%62%
2401
September1st to 15thDay
3313324447%59%
1980
16th to endDay
22221334471%
1828
October1st to 15thDay
5%21221235%5%65%
1755
16th to endDay
32232323470%
1760
November1st to 15thDay
3312213335%68%
1592
16th to endDay
6%312212336%66%
1620
December1st to 15thDay
5%7%13323347%56%
1620
16th to endDay
12%7%13313336%52%
1728
January1st to 15thNight
8%412212235%63%
2327
16th to endNight
8%5%1321434458%
2496
February1st to 15thNight
5%6%13323346%59%
2191
16th to endNight
9%8%13324346%51%
1895
March1st to 15thNight
6%5%2232335%6%59%
2034
16th to endNight
5%31322345%7%61%
2112
April1st to 15thNight
6%313323345%60%
1922
16th to endNight
4313213247%64%
1620
May1st to 15thNight
4212213437%65%
1619
16th to endNight
331322343467%
1684
June1st to 15thNight
111113346%74%
1620
16th to endNight
121222480%
1620
July1st to 15thNight
12123245%5%9%61%
1620
16th to endNight
4314435%6%7%9%48%
1701
August1st to 15thNight
221332335%8%63%
1620
16th to endNight
32122235%5%7%65%
1797
September1st to 15thNight
421321335%7%63%
1980
16th to endNight
111112235%78%
1837
October1st to 15thNight
5%21232333467%
1874
16th to endNight
3211213245%71%
2112
November1st to 15thNight
3213312336%66%
2264
16th to endNight
4312313236%67%
2340
December1st to 15thNight
8%5%3322346%58%
2340
16th to endNight
10%6%23323346%53%
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
24%310%28%29%2
1612
16th to endDay
28%410%26%21%8%
1728
February1st to 15thDay
25%411%24%24%9%
1659
16th to endDay
32%37%18%28%8%
1579
March1st to 15thDay
21%36%26%33%8%
1926
16th to endDay
25%38%24%26%10%
2112
April1st to 15thDay
25%37%20%27%16%
2020
16th to endDay
20%25%21%32%17%
2340
May1st to 15thDay
20%47%17%32%17%
2331
16th to endDay
18%48%15%31%21%
2432
June1st to 15thDay
12%238%25%46%
2340
16th to endDay
9%125%18%62%
2340
July1st to 15thDay
23%47%12%15%36%
2201
16th to endDay
30%7%10%16%15%19%
2312
August1st to 15thDay
23%5%7%15%18%29%
2325
16th to endDay
19%48%14%26%27%
2401
September1st to 15thDay
22%48%13%18%33%
1980
16th to endDay
14%25%15%25%37%
1828
October1st to 15thDay
18%35%17%32%21%
1755
16th to endDay
17%26%18%35%19%
1760
November1st to 15thDay
18%28%22%31%16%
1592
16th to endDay
19%36%24%30%14%
1620
December1st to 15thDay
27%412%26%25%3
1620
16th to endDay
33%415%22%19%4
1728
January1st to 15thNight
24%39%29%27%5%
2327
16th to endNight
28%48%24%23%9%
2496
February1st to 15thNight
26%39%23%24%12%
2202
16th to endNight
31%47%18%30%8%
1895
March1st to 15thNight
24%26%25%34%7%
2034
16th to endNight
21%48%25%27%12%
2112
April1st to 15thNight
24%27%20%29%14%
1922
16th to endNight
18%35%20%36%16%
1620
May1st to 15thNight
18%37%16%34%19%
1620
16th to endNight
19%35%15%33%22%
1685
June1st to 15thNight
11%248%25%47%
1620
16th to endNight
8%125%16%64%
1620
July1st to 15thNight
18%5%9%12%16%37%
1530
16th to endNight
28%5%9%19%15%21%
1593
August1st to 15thNight
18%48%15%19%33%
1611
16th to endNight
18%47%14%24%30%
1797
September1st to 15thNight
19%38%15%18%34%
1980
16th to endNight
10%15%16%25%40%
1837
October1st to 15thNight
20%2416%31%23%
1874
16th to endNight
15%27%14%37%22%
2112
November1st to 15thNight
18%29%20%34%14%
2264
16th to endNight
20%35%19%35%16%
2340
December1st to 15thNight
25%310%27%26%5%
2340
16th to endNight
31%413%25%20%4
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
36%425%20%12%1
90
16th to endDay
15%5%12%38%23%4
96
February1st to 15thDay
10%9%26%28%19%5%
174
16th to endDay
17%21%32%18%8%1
238
March1st to 15thDay
10%19%26%28%11%2
270
16th to endDay
9%22%34%23%10%
288
April1st to 15thDay
11%26%29%20%8%4
269
16th to endDay
12%30%27%21%7%1
270
May1st to 15thDay
9%18%39%21%8%2
288
16th to endDay
9%17%31%26%11%3
330
June1st to 15thDay
315%38%31%9%2
315
16th to endDay
15%30%37%20%5%
315
July1st to 15thDay
3332%40%15%5%
305
16th to endDay
8%122%46%16%5%
327
August1st to 15thDay
4326%42%16%6%
315
16th to endDay
6%121%41%19%8%
332
September1st to 15thDay
3433%34%19%5%
315
16th to endDay
5%10%23%34%22%3
260
October1st to 15thDay
6%11%32%27%18%2
195
16th to endDay
11%5%22%47%11%1
96
November1st to 15thDay
5%5%18%33%30%6%
90
16th to endDay
14%7%35%38%21
90
December1st to 15thDay
3322%52%17%1
90
16th to endDay
19%6%19%31%18%4
96
January1st to 15thNight
11%213%42%23%6%
720
16th to endNight
12%114%40%24%5%
768
February1st to 15thNight
9%115%44%24%4
704
16th to endNight
13%221%39%20%3
632
March1st to 15thNight
9%5%19%37%24%4
720
16th to endNight
5%6%19%39%25%3
768
April1st to 15thNight
8%7%23%33%22%4
713
16th to endNight
6%10%22%37%19%5%
540
May1st to 15thNight
5%5%20%41%22%4
540
16th to endNight
46%20%33%30%4
563
June1st to 15thNight
3316%41%32%2
540
16th to endNight
212%41%39%3
540
July1st to 15thNight
35%31%53%6%
510
16th to endNight
6%428%53%7%
564
August1st to 15thNight
3430%54%6%
539
16th to endNight
4427%49%13%
648
September1st to 15thNight
5%5%30%46%11%
720
16th to endNight
3110%30%39%14%
664
October1st to 15thNight
5%214%43%26%8%
660
16th to endNight
4115%35%32%9%
704
November1st to 15thNight
4112%43%30%7%
700
16th to endNight
7%213%39%30%6%
720
December1st to 15thNight
12%112%45%22%5%
720
16th to endNight
14%315%41%23%2
768
Page generated at 2017-09-18 06:38:20. Version ac04

Copyright 2017 A. Danko


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