Glenn Canyon's Wahweap district
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Glenn Canyon's Wahweap district clear sky chart from 2005-11-06 to 2024-01-14.

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
72%
23882
31%
74453
27%
23842
77%
23842
48%
36477

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 10thNight
69%
756
23%
2457
22%
756
74%
756
36%
1385
January11th to 20thNight
70%
734
28%
2385
27%
734
75%
734
39%
1270
January21st to endNight
65%
792
29%
2574
28%
792
70%
792
35%
1427
February1st to 10thNight
69%
720
28%
2340
28%
720
76%
720
44%
1165
February11th to 20thNight
60%
700
28%
2144
24%
700
69%
700
42%
1128
February21st to endNight
62%
592
34%
1776
30%
592
71%
592
47%
922
March1st to 10thNight
65%
720
31%
1982
25%
720
71%
720
50%
1028
March11th to 20thNight
66%
720
33%
1980
27%
720
71%
720
50%
1045
March21st to endNight
61%
792
33%
2178
19%
792
73%
792
51%
1128
April1st to 10thNight
59%
720
30%
1980
16%
720
68%
720
53%
994
April11th to 20thNight
58%
543
35%
1750
23%
543
70%
543
49%
804
April21st to endNight
59%
540
39%
1620
25%
540
70%
540
54%
745
May1st to 10thNight
64%
540
33%
1620
24%
540
71%
540
51%
781
May11th to 20thNight
71%
531
35%
1595
28%
531
75%
531
60%
696
May21st to endNight
64%
582
30%
1746
21%
582
72%
582
57%
780
June1st to 10thNight
76%
540
33%
1620
28%
540
80%
540
66%
684
June11th to 20thNight
71%
540
32%
1620
29%
540
74%
540
65%
686
June21st to endNight
83%
540
33%
1620
32%
540
84%
540
70%
666
July1st to 10thNight
83%
525
25%
1575
23%
525
83%
525
51%
775
July11th to 20thNight
81%
522
24%
1566
22%
522
81%
522
45%
821
July21st to endNight
80%
591
22%
1674
21%
558
80%
558
32%
1000
August1st to 10thNight
84%
537
29%
1602
25%
534
85%
534
51%
779
August11th to 20thNight
82%
534
34%
1602
30%
534
83%
534
47%
820
August21st to endNight
84%
594
36%
1866
35%
594
85%
594
49%
902
September1st to 10thNight
83%
706
33%
1966
30%
706
85%
706
57%
977
September11th to 20thNight
84%
720
40%
1980
34%
720
86%
720
62%
945
September21st to endNight
79%
720
40%
1980
29%
720
85%
720
66%
907
October1st to 10thNight
74%
720
32%
2057
25%
720
78%
720
54%
1012
October11th to 20thNight
78%
720
41%
2160
35%
720
83%
720
66%
927
October21st to endNight
75%
792
42%
2376
35%
792
81%
792
59%
1080
November1st to 10thNight
81%
740
40%
2275
36%
740
85%
740
62%
984
November11th to 20thNight
80%
760
41%
2470
40%
760
86%
760
64%
1004
November21st to endNight
73%
760
35%
2470
32%
760
80%
760
52%
1136
December1st to 10thNight
70%
760
30%
2470
29%
760
74%
760
44%
1223
December11th to 20thNight
70%
758
22%
2997
24%
758
75%
758
32%
1587
December21st to endNight
61%
821
15%
4380
21%
817
66%
817
21%
2264

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
331343445%8%62%
74956
Night
331342445%8%62%
74843
TransparencyDay
19%6%10%20%25%21%
74683
Night
19%6%10%20%25%20%
74638
SeeingDay
46%15%31%29%15%
13686
Night
4316%42%32%4
23909

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 10thDay
2427%9%6%7%7%6%8%41%
1708
11th to 20thDay
45%25%436%5%6%10%50%
1647
21st to endDay
4327%7%445%5%9%49%
1782
February1st to 10thDay
14245%35%5%6%10%54%
1620
11th to 20thDay
3425%5%35%6%7%11%49%
1700
21st to endDay
34245%35%6%6%9%54%
1480
March1st to 10thDay
33234345%6%9%58%
1976
11th to 20thDay
2416%43446%8%59%
1980
21st to endDay
332333345%10%62%
2178
April1st to 10thDay
221342345%7%66%
1980
11th to 20thDay
131332345%6%69%
2154
21st to endDay
221232335%6%70%
2340
May1st to 10thDay
221233445%8%66%
2340
11th to 20thDay
221222445%9%67%
2301
21st to endDay
321222345%7%70%
2530
June1st to 10thDay
1112212336%77%
2340
11th to 20thDay
2111212335%79%
2340
21st to endDay
1112122345%78%
2340
July1st to 10thDay
121343446%8%63%
2340
11th to 20thDay
2213446%6%9%11%51%
2340
21st to endDay
3315%6%5%6%8%9%13%42%
2545
August1st to 10thDay
23145%35%5%9%8%54%
2328
11th to 20thDay
2213445%6%7%10%57%
2299
21st to endDay
33134245%6%8%61%
2489
September1st to 10thDay
321342335%7%67%
1991
11th to 20thDay
2213323346%70%
1980
21st to endDay
2112222245%77%
1980
October1st to 10thDay
4213323446%68%
1901
11th to 20thDay
221222224478%
1800
21st to endDay
231231335%6%73%
1980
November1st to 10thDay
2212212346%76%
1802
11th to 20thDay
1212323347%73%
1710
21st to endDay
332432445%7%63%
1710
December1st to 10thDay
36%35%4235%5%10%54%
1710
11th to 20thDay
5%6%310%8%46%6%6%10%36%
2169
21st to endDay
6%7%25%6%47%6%7%8%42%
3146
January1st to 10thNight
4326%5%46%5%6%10%49%
2457
11th to 20thNight
44244245%7%9%52%
2385
21st to endNight
4427%5%445%5%8%53%
2574
February1st to 10thNight
2314425%5%7%8%58%
2340
11th to 20thNight
34246%35%5%6%8%53%
2143
21st to endNight
34243345%7%8%58%
1776
March1st to 10thNight
34133345%5%10%60%
1982
11th to 20thNight
442432446%7%61%
1980
21st to endNight
321342446%8%63%
2178
April1st to 10thNight
231333435%7%67%
1980
11th to 20thNight
231332445%7%67%
1750
21st to endNight
3213323347%69%
1620
May1st to 10thNight
321332446%7%65%
1620
11th to 20thNight
2212223448%71%
1594
21st to endNight
321232335%7%70%
1746
June1st to 10thNight
2111212446%75%
1620
11th to 20thNight
222223346%76%
1620
21st to endNight
112222347%76%
1620
July1st to 10thNight
2213435%6%6%9%60%
1620
11th to 20thNight
3223435%5%7%12%55%
1620
21st to endNight
2315%7%5%7%9%9%12%42%
1773
August1st to 10thNight
1213335%48%8%62%
1611
11th to 20thNight
22134347%6%8%59%
1602
21st to endNight
22134345%6%10%60%
1866
September1st to 10thNight
32133245%5%8%64%
1966
11th to 20thNight
2312213347%71%
1980
21st to endNight
2212212335%76%
1980
October1st to 10thNight
332332335%6%68%
2057
11th to 20thNight
221221122479%
2160
21st to endNight
4213322336%73%
2376
November1st to 10thNight
2212213337%73%
2275
11th to 20thNight
1212214335%76%
2470
21st to endNight
422232445%7%66%
2470
December1st to 10thNight
442442345%9%60%
2470
11th to 20thNight
4425%5%45%6%8%14%43%
3041
21st to endNight
5%5%26%6%35%5%6%9%46%
4521

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 10thDay
36%8%18%26%12%1
1709
11th to 20thDay
26%8%16%29%19%1
1647
21st to endDay
30%7%15%29%17%3
1782
February1st to 10thDay
24%6%15%25%24%6%
1620
11th to 20thDay
25%6%9%28%25%8%
1710
21st to endDay
23%6%12%21%28%10%
1480
March1st to 10thDay
20%6%10%24%32%9%
1976
11th to 20thDay
21%6%9%26%28%10%
1980
21st to endDay
19%5%9%26%31%10%
2178
April1st to 10thDay
18%47%20%32%19%
1980
11th to 20thDay
16%46%20%31%22%
2157
21st to endDay
14%5%5%17%36%22%
2340
May1st to 10thDay
17%5%6%17%33%23%
2340
11th to 20thDay
14%48%19%34%20%
2304
21st to endDay
14%5%6%16%30%28%
2530
June1st to 10thDay
9%4410%30%43%
2340
11th to 20thDay
10%247%18%59%
2340
21st to endDay
9%347%20%57%
2340
July1st to 10thDay
18%6%8%11%15%41%
2276
11th to 20thDay
22%8%16%15%18%21%
2271
21st to endDay
28%11%16%18%13%13%
2404
August1st to 10thDay
23%8%11%17%15%26%
2313
11th to 20thDay
20%8%11%15%17%28%
2299
21st to endDay
20%6%10%14%25%25%
2489
September1st to 10thDay
17%5%8%14%20%36%
1991
11th to 20thDay
15%5%7%15%22%35%
1980
21st to endDay
12%36%13%32%34%
1980
October1st to 10thDay
17%5%8%19%26%26%
1901
11th to 20thDay
11%35%15%38%28%
1800
21st to endDay
13%48%23%38%15%
1980
November1st to 10thDay
11%38%30%36%12%
1802
11th to 20thDay
12%49%32%36%7%
1710
21st to endDay
20%6%9%29%30%7%
1710
December1st to 10thDay
24%8%15%29%19%5%
1710
11th to 20thDay
37%10%18%25%10%1
2168
21st to endDay
33%8%14%26%16%4
3146
January1st to 10thNight
26%9%18%28%17%1
2457
11th to 20thNight
24%8%16%30%20%2
2385
21st to endNight
28%7%12%28%21%4
2574
February1st to 10thNight
21%7%13%26%26%7%
2340
11th to 20thNight
24%6%9%25%26%9%
2144
21st to endNight
20%7%11%25%28%10%
1776
March1st to 10thNight
20%5%11%22%31%10%
1982
11th to 20thNight
20%6%7%22%33%12%
1980
21st to endNight
18%6%9%25%31%11%
2178
April1st to 10thNight
18%47%18%32%21%
1980
11th to 20thNight
18%46%16%30%26%
1750
21st to endNight
15%5%5%17%40%19%
1620
May1st to 10thNight
16%6%7%12%34%25%
1620
11th to 20thNight
12%5%8%16%34%26%
1595
21st to endNight
13%48%16%28%30%
1746
June1st to 10thNight
11%348%26%47%
1620
11th to 20thNight
11%35%8%16%57%
1620
21st to endNight
10%237%19%59%
1620
July1st to 10thNight
19%5%9%14%12%41%
1575
11th to 20thNight
21%8%13%15%17%26%
1566
21st to endNight
30%10%13%18%13%15%
1674
August1st to 10thNight
17%7%13%20%16%28%
1602
11th to 20thNight
19%8%10%17%17%29%
1602
21st to endNight
18%6%8%16%22%30%
1866
September1st to 10thNight
17%48%16%18%36%
1966
11th to 20thNight
14%47%16%19%40%
1980
21st to endNight
11%35%13%28%39%
1980
October1st to 10thNight
17%5%8%17%25%29%
2057
11th to 20thNight
12%3411%34%37%
2160
21st to endNight
14%46%18%38%20%
2376
November1st to 10thNight
13%36%24%37%18%
2275
11th to 20thNight
11%47%27%42%10%
2470
21st to endNight
17%5%9%23%35%11%
2470
December1st to 10thNight
20%7%14%30%23%6%
2470
11th to 20thNight
25%10%23%27%14%1
3041
21st to endNight
31%8%14%24%18%5%
4521

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 10thDay
6%5%14%46%23%7%
270
11th to 20thDay
9%5%13%38%24%10%
249
21st to endDay
3312%39%30%13%
264
February1st to 10thDay
3313%40%30%11%
240
11th to 20thDay
7%7%22%36%23%5%
366
21st to endDay
311%25%36%21%4
346
March1st to 10thDay
6%9%21%37%20%6%
420
11th to 20thDay
5%10%17%38%23%7%
420
21st to endDay
7%14%26%34%17%3
462
April1st to 10thDay
5%14%24%30%18%11%
420
11th to 20thDay
5%17%24%31%18%5%
412
21st to endDay
415%24%26%22%9%
420
May1st to 10thDay
5%11%26%28%25%5%
423
11th to 20thDay
49%21%28%24%14%
448
21st to endDay
6%8%21%27%26%12%
485
June1st to 10thDay
25%16%34%28%14%
450
11th to 20thDay
27%19%28%28%16%
450
21st to endDay
2315%33%34%14%
450
July1st to 10thDay
119%27%39%23%
446
11th to 20thDay
217%26%33%32%
444
21st to endDay
217%21%37%32%
487
August1st to 10thDay
417%29%35%24%
447
11th to 20thDay
2111%25%36%24%
437
21st to endDay
417%23%39%25%
495
September1st to 10thDay
2211%24%35%25%
450
11th to 20thDay
2312%28%38%17%
450
21st to endDay
36%10%28%32%20%
450
October1st to 10thDay
5%5%14%29%26%20%
371
11th to 20thDay
4315%23%35%20%
270
21st to endDay
5%313%27%38%14%
297
November1st to 10thDay
3316%32%31%16%
270
11th to 20thDay
2310%32%37%17%
270
21st to endDay
3414%33%30%14%
270
December1st to 10thDay
6%310%40%30%11%
270
11th to 20thDay
4410%38%31%13%
270
21st to endDay
13%5%11%43%22%6%
297
January1st to 10thNight
5%315%44%28%6%
760
11th to 20thNight
5%215%47%27%4
734
21st to endNight
6%117%47%26%4
792
February1st to 10thNight
4218%46%27%3
720
11th to 20thNight
4424%45%20%2
704
21st to endNight
6%327%47%16%1
592
March1st to 10thNight
46%20%48%22%1
720
11th to 20thNight
4419%42%28%3
720
21st to endNight
35%27%46%18%1
792
April1st to 10thNight
35%29%40%21%2
720
11th to 20thNight
47%27%42%19%
543
21st to endNight
45%27%40%21%3
540
May1st to 10thNight
45%22%48%20%1
540
11th to 20thNight
25%18%43%30%2
531
21st to endNight
35%23%41%24%3
584
June1st to 10thNight
2415%49%28%1
540
11th to 20thNight
2320%45%28%2
540
21st to endNight
112%48%38%1
540
July1st to 10thNight
217%40%47%3
525
11th to 20thNight
316%39%46%5%
522
21st to endNight
31430%57%5%
591
August1st to 10thNight
315%37%50%4
537
11th to 20thNight
225%40%46%4
534
21st to endNight
117%36%49%6%
594
September1st to 10thNight
317%33%49%7%
706
11th to 20thNight
317%38%47%4
720
21st to endNight
3312%33%43%7%
720
October1st to 10thNight
4215%41%35%3
720
11th to 20thNight
3114%40%36%6%
720
21st to endNight
5%214%37%36%7%
792
November1st to 10thNight
2212%44%34%4
740
11th to 20thNight
1114%46%32%6%
760
21st to endNight
4216%43%30%5%
760
December1st to 10thNight
5%215%49%25%4
760
11th to 20thNight
6%414%43%30%3
760
21st to endNight
6%419%47%22%3
836
Page generated at 2024-01-11 02:22:42. Version ac07

Copyright 2024 Attilla Danko


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