Mount Dellenbaugh
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mount Dellenbaugh clear sky chart from 2005-11-05 to 2017-09-22.

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%
15759
34%
46989
29%
15723
75%
15723
53%
22389

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%
716
31%
2327
30%
716
72%
716
47%
1116
January16th to endNight
63%
768
34%
2496
31%
768
71%
768
42%
1254
February1st to 15thNight
67%
699
31%
2154
29%
699
73%
699
48%
1074
February16th to endNight
58%
632
33%
1895
33%
632
65%
632
42%
1013
March1st to 15thNight
61%
720
35%
2048
28%
720
70%
720
52%
1013
March16th to endNight
65%
768
34%
2112
25%
768
73%
768
55%
1043
April1st to 15thNight
54%
719
29%
1912
15%
719
62%
719
49%
996
April16th to endNight
61%
567
40%
1647
24%
567
71%
567
57%
725
May1st to 15thNight
67%
539
35%
1619
25%
539
72%
539
59%
712
May16th to endNight
65%
561
34%
1685
25%
561
70%
561
57%
740
June1st to 15thNight
72%
540
31%
1620
26%
540
77%
540
68%
669
June16th to endNight
80%
540
33%
1620
31%
540
82%
540
73%
647
July1st to 15thNight
81%
510
25%
1530
24%
510
81%
510
48%
765
July16th to endNight
80%
564
27%
1593
24%
531
80%
531
43%
846
August1st to 15thNight
82%
539
33%
1611
27%
536
82%
536
51%
782
August16th to endNight
83%
702
41%
1848
30%
702
84%
702
59%
929
September1st to 15thNight
81%
720
32%
1974
26%
720
82%
720
56%
998
September16th to endNight
80%
683
46%
1890
36%
683
86%
683
73%
809
October1st to 15thNight
75%
660
40%
1851
33%
660
79%
660
60%
866
October16th to endNight
74%
704
40%
2112
33%
704
81%
704
62%
924
November1st to 15thNight
74%
700
35%
2269
35%
700
79%
700
57%
982
November16th to endNight
71%
720
39%
2340
37%
720
79%
720
55%
1028
December1st to 15thNight
68%
720
32%
2340
31%
720
73%
720
48%
1117
December16th to endNight
58%
768
30%
2496
28%
768
63%
768
37%
1341

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
4313323345%63%
47898
Night
4312223346%65%
47184
TransparencyDay
20%36%16%27%25%
47593
Night
18%27%17%28%25%
46990
SeeingDay
7%11%28%33%14%3
5545
Night
5%314%37%33%5%
15771

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
3414422335%64%
1611
16th to endDay
7%5%13323347%57%
1728
February1st to 15thDay
45%1332345%5%60%
1706
16th to endDay
8%7%22424346%53%
1579
March1st to 15thDay
4422323446%62%
1911
16th to endDay
35%1342345%7%58%
2112
April1st to 15thDay
5%324423435%59%
2035
16th to endDay
331222332471%
2313
May1st to 15thDay
3312213345%67%
2331
16th to endDay
3312323235%69%
2429
June1st to 15thDay
12112222378%
2340
16th to endDay
2111222381%
2340
July1st to 15thDay
32245%25%45%5%58%
2340
16th to endDay
7%425%5%46%5%7%7%42%
2467
August1st to 15thDay
421333446%8%56%
2340
16th to endDay
421342446%5%59%
2351
September1st to 15thDay
4213424446%60%
1986
16th to endDay
21221222476%
1882
October1st to 15thDay
421222234469%
1779
16th to endDay
221231223472%
1760
November1st to 15thDay
232221223471%
1590
16th to endDay
5%31221223469%
1620
December1st to 15thDay
46%245%23346%56%
1620
16th to endDay
9%7%14323336%54%
1728
January1st to 15thNight
5%413323335%63%
2327
16th to endNight
7%6%14223335%59%
2496
February1st to 15thNight
35%23422336%63%
2143
16th to endNight
7%6%13333346%56%
1895
March1st to 15thNight
331342346%6%60%
2048
16th to endNight
321332335%7%63%
2112
April1st to 15thNight
4423314345%63%
1912
16th to endNight
222212346%70%
1647
May1st to 15thNight
321222346%69%
1619
16th to endNight
222213346%70%
1684
June1st to 15thNight
11211222378%
1620
16th to endNight
11121222382%
1620
July1st to 15thNight
3213325%45%7%60%
1620
16th to endNight
3313435%6%6%9%50%
1701
August1st to 15thNight
221332436%6%62%
1620
16th to endNight
2212223448%65%
1848
September1st to 15thNight
431222245%6%64%
1974
16th to endNight
1121112482%
1890
October1st to 15thNight
321211223472%
1851
16th to endNight
3212112245%72%
2112
November1st to 15thNight
2313212345%68%
2269
16th to endNight
4312212336%68%
2340
December1st to 15thNight
7%3232445%7%59%
2340
16th to endNight
9%6%24413336%54%
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
21%38%24%35%7%
1612
16th to endDay
25%29%23%27%10%
1728
February1st to 15thDay
23%211%20%26%15%
1706
16th to endDay
29%27%19%27%13%
1579
March1st to 15thDay
19%35%21%37%12%
1911
16th to endDay
22%17%21%30%15%
2112
April1st to 15thDay
24%26%16%27%22%
2035
16th to endDay
16%1418%33%25%
2313
May1st to 15thDay
17%25%16%32%25%
2331
16th to endDay
18%15%11%33%29%
2432
June1st to 15thDay
11%128%21%56%
2340
16th to endDay
9%115%17%64%
2340
July1st to 15thDay
25%5%5%10%14%38%
2201
16th to endDay
34%7%9%16%15%16%
2312
August1st to 15thDay
23%6%7%12%20%30%
2325
16th to endDay
23%45%12%28%25%
2351
September1st to 15thDay
22%47%12%22%30%
1986
16th to endDay
13%1412%29%39%
1882
October1st to 15thDay
17%2415%30%29%
1779
16th to endDay
15%26%14%34%27%
1760
November1st to 15thDay
16%15%21%33%21%
1590
16th to endDay
18%15%21%32%20%
1620
December1st to 15thDay
26%312%23%27%6%
1620
16th to endDay
30%411%24%23%5%
1728
January1st to 15thNight
22%27%25%33%9%
2327
16th to endNight
25%28%21%28%13%
2496
February1st to 15thNight
22%39%19%27%17%
2154
16th to endNight
27%26%18%31%13%
1895
March1st to 15thNight
19%26%20%39%11%
2048
16th to endNight
17%38%22%32%16%
2112
April1st to 15thNight
20%16%18%32%19%
1912
16th to endNight
13%25%17%33%28%
1647
May1st to 15thNight
13%25%16%31%29%
1620
16th to endNight
13%25%11%37%30%
1685
June1st to 15thNight
10%126%21%56%
1620
16th to endNight
8%116%13%68%
1620
July1st to 15thNight
20%5%7%12%13%41%
1530
16th to endNight
24%6%9%21%18%20%
1593
August1st to 15thNight
19%46%14%21%34%
1611
16th to endNight
16%36%15%27%29%
1848
September1st to 15thNight
18%29%15%21%31%
1974
16th to endNight
8%1312%28%44%
1890
October1st to 15thNight
14%2415%31%30%
1851
16th to endNight
13%17%12%30%34%
2112
November1st to 15thNight
15%16%19%35%20%
2269
16th to endNight
16%16%19%31%24%
2340
December1st to 15thNight
20%311%26%27%10%
2340
16th to endNight
29%312%23%25%5%
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
21%7%27%35%6%1
90
16th to endDay
11%6%17%36%22%5%
96
February1st to 15thDay
7%15%23%30%19%4
221
16th to endDay
17%21%30%20%8%1
238
March1st to 15thDay
10%18%31%24%12%2
270
16th to endDay
11%20%33%23%9%2
288
April1st to 15thDay
12%24%27%26%5%4
269
16th to endDay
13%26%30%21%6%1
270
May1st to 15thDay
7%17%40%21%11%1
288
16th to endDay
6%18%31%30%10%3
330
June1st to 15thDay
315%35%30%11%3
315
16th to endDay
35%36%32%18%4
315
July1st to 15thDay
4332%40%15%4
305
16th to endDay
7%118%45%22%4
327
August1st to 15thDay
8%324%42%17%4
315
16th to endDay
5%219%43%22%6%
332
September1st to 15thDay
46%27%43%13%4
315
16th to endDay
5%11%25%37%15%5%
280
October1st to 15thDay
5%12%33%29%14%4
219
16th to endDay
9%5%23%33%26%2
96
November1st to 15thDay
46%16%32%34%5%
90
16th to endDay
5%10%33%37%13%
90
December1st to 15thDay
1422%52%18%1
90
16th to endDay
15%6%22%43%9%2
96
January1st to 15thNight
7%217%41%25%5%
720
16th to endNight
10%215%42%23%4
768
February1st to 15thNight
6%116%47%24%3
704
16th to endNight
7%6%23%41%18%2
632
March1st to 15thNight
46%23%37%26%2
720
16th to endNight
45%19%39%28%3
768
April1st to 15thNight
6%10%22%34%21%3
719
16th to endNight
310%20%38%22%4
567
May1st to 15thNight
5%5%17%41%27%3
540
16th to endNight
37%18%36%30%3
563
June1st to 15thNight
2316%40%31%5%
540
16th to endNight
1211%36%43%4
540
July1st to 15thNight
46%28%53%7%
510
16th to endNight
4225%57%9%
564
August1st to 15thNight
2331%57%4
539
16th to endNight
3425%51%14%
702
September1st to 15thNight
46%32%45%10%
720
16th to endNight
2111%31%40%11%
683
October1st to 15thNight
3313%42%31%6%
660
16th to endNight
5%312%34%36%7%
704
November1st to 15thNight
3215%40%33%6%
700
16th to endNight
5%414%39%31%5%
720
December1st to 15thNight
9%115%45%25%3
720
16th to endNight
11%419%42%21%2
768
Page generated at 2017-09-23 03:43:35. Version ac04

Copyright 2017 A. Danko


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