This page made possible by the sponsorship of: Dr. John Sohl.

Ogden
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ogden clear sky chart from 2005-11-05 to 2020-06-03.

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
57%
19305
21%
57764
18%
19268
60%
19268
30%
35867

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
48%
896
10%
2912
10%
896
49%
896
17%
2100
January16th to endNight
47%
960
12%
3120
13%
960
49%
960
16%
2294
February1st to 15thNight
46%
879
12%
2873
13%
878
48%
878
18%
2047
February16th to endNight
45%
792
19%
2396
17%
792
49%
792
21%
1657
March1st to 15thNight
53%
900
18%
2531
16%
900
56%
900
26%
1703
March16th to endNight
48%
960
17%
2640
12%
960
51%
960
25%
1839
April1st to 15thNight
46%
809
16%
2320
12%
809
49%
809
26%
1533
April16th to endNight
55%
669
25%
2007
20%
669
57%
669
30%
1241
May1st to 15thNight
59%
674
22%
2024
17%
674
61%
674
33%
1189
May16th to endNight
58%
705
17%
2117
15%
705
59%
705
27%
1338
June1st to 15thNight
69%
637
24%
1733
21%
637
72%
637
48%
930
June16th to endNight
69%
472
30%
1591
32%
472
77%
472
60%
639
July1st to 15thNight
75%
517
22%
1717
24%
517
78%
517
44%
850
July16th to endNight
79%
660
25%
1881
23%
627
79%
627
49%
940
August1st to 15thNight
76%
620
29%
1854
24%
617
78%
617
46%
952
August16th to endNight
77%
669
36%
2010
29%
669
79%
669
50%
993
September1st to 15thNight
75%
798
30%
2268
26%
798
78%
798
50%
1160
September16th to endNight
71%
836
34%
2310
27%
836
74%
836
52%
1198
October1st to 15thNight
64%
840
28%
2446
23%
840
67%
840
41%
1364
October16th to endNight
63%
896
32%
2708
27%
896
68%
896
39%
1509
November1st to 15thNight
60%
880
24%
2860
23%
880
63%
880
31%
1679
November16th to endNight
55%
1012
18%
3037
18%
1012
56%
1012
27%
1933
December1st to 15thNight
45%
1125
10%
3150
9%
1125
47%
1125
21%
2287
December16th to endNight
39%
1099
11%
3259
9%
1099
41%
1099
15%
2492

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
9%7%2442345%6%48%
58617
Night
11%7%24423446%47%
57958
TransparencyDay
35%6%11%18%18%10%
58311
Night
37%5%11%20%16%8%
57765
SeeingDay
12%5%23%35%19%3
9138
Night
14%217%38%23%2
19317

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
15%14%47%435%5%45%29%
2016
16th to endDay
15%15%5%5%5%35%5%5%5%26%
2160
February1st to 15thDay
16%15%46%43345%5%29%
1980
16th to endDay
11%15%6%7%5%3445%6%29%
1954
March1st to 15thDay
10%10%46%5%245%6%7%36%
2419
16th to endDay
15%10%36%5%35%5%6%7%31%
2640
April1st to 15thDay
16%8%25%5%2445%7%36%
2614
16th to endDay
10%8%25%424447%44%
2888
May1st to 15thDay
8%6%25%4245%5%8%45%
2916
16th to endDay
12%5%25%5%35%5%6%8%40%
3053
June1st to 15thDay
5%324323448%56%
2929
16th to endDay
322211235%73%
3015
July1st to 15thDay
321332335%7%63%
2808
16th to endDay
421321345%6%63%
2883
August1st to 15thDay
3212323447%65%
2680
16th to endDay
3212313346%66%
2896
September1st to 15thDay
4212323345%66%
2350
16th to endDay
7%212222345%66%
2310
October1st to 15thDay
11%413423446%52%
2174
16th to endDay
8%5%24423447%52%
2216
November1st to 15thDay
13%7%23423447%47%
1989
16th to endDay
14%10%34423447%39%
1895
December1st to 15thDay
15%12%37%5%35%45%5%31%
1800
16th to endDay
17%16%47%434336%25%
2032
January1st to 15thNight
17%11%36%5%23346%34%
2912
16th to endNight
15%14%36%433446%33%
3120
February1st to 15thNight
15%12%35%5%33445%35%
2862
16th to endNight
11%12%46%5%235%5%6%36%
2396
March1st to 15thNight
13%9%35%42335%7%40%
2531
16th to endNight
12%11%35%5%24446%38%
2640
April1st to 15thNight
14%9%35%5%2434442%
2320
16th to endNight
11%6%25%42335%6%47%
2007
May1st to 15thNight
8%5%1442446%7%49%
2024
16th to endNight
13%5%25%42445%7%43%
2116
June1st to 15thNight
6%21322345%7%60%
1733
16th to endNight
322211245%72%
1591
July1st to 15thNight
331332446%7%56%
1806
16th to endNight
331322345%8%60%
1989
August1st to 15thNight
32144345%5%7%58%
1863
16th to endNight
331232345%7%62%
2010
September1st to 15thNight
4312323445%64%
2268
16th to endNight
7%31221233467%
2310
October1st to 15thNight
9%422323345%57%
2446
16th to endNight
8%5%14323336%57%
2708
November1st to 15thNight
11%6%24423346%51%
2860
16th to endNight
12%8%245%3435%6%43%
3037
December1st to 15thNight
15%11%37%42335%6%35%
3150
16th to endNight
20%13%47%6%24346%27%
3259

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
54%10%18%12%2
2017
16th to endDay
56%10%18%11%3
2160
February1st to 15thDay
55%8%14%13%6%1
1980
16th to endDay
54%7%14%16%5%1
1954
March1st to 15thDay
43%9%15%21%9%
2419
16th to endDay
49%7%14%19%7%1
2640
April1st to 15thDay
45%7%12%19%12%1
2614
16th to endDay
38%6%10%23%20%1
2888
May1st to 15thDay
34%6%9%25%19%4
2916
16th to endDay
37%8%10%22%18%3
3056
June1st to 15thDay
25%5%9%20%29%10%
2929
16th to endDay
14%2412%31%34%
3015
July1st to 15thDay
19%36%15%26%28%
2668
16th to endDay
19%46%11%26%32%
2728
August1st to 15thDay
17%37%14%26%30%
2665
16th to endDay
17%35%15%33%23%
2896
September1st to 15thDay
20%36%15%30%23%
2350
16th to endDay
20%38%22%34%11%
2310
October1st to 15thDay
32%5%9%25%20%6%
2174
16th to endDay
30%6%14%29%17%1
2216
November1st to 15thDay
37%6%15%23%16%
1989
16th to endDay
44%5%18%21%8%
1895
December1st to 15thDay
53%10%17%12%4
1800
16th to endDay
60%7%13%12%4
2032
January1st to 15thNight
51%8%19%16%3
2912
16th to endNight
51%9%16%14%5%1
3120
February1st to 15thNight
50%7%14%18%8%
2873
16th to endNight
47%6%12%24%7%1
2396
March1st to 15thNight
43%5%13%25%11%
2531
16th to endNight
45%6%12%23%9%2
2640
April1st to 15thNight
44%312%23%12%3
2320
16th to endNight
37%5%9%24%20%2
2007
May1st to 15thNight
32%6%9%23%22%6%
2025
16th to endNight
37%7%11%21%18%3
2117
June1st to 15thNight
21%5%10%20%32%10%
1733
16th to endNight
14%16%13%27%37%
1591
July1st to 15thNight
23%37%13%23%27%
1717
16th to endNight
21%46%12%23%31%
1881
August1st to 15thNight
22%47%13%21%29%
1854
16th to endNight
20%46%12%30%25%
2010
September1st to 15thNight
22%36%13%26%28%
2268
16th to endNight
21%26%18%31%19%
2310
October1st to 15thNight
27%49%25%25%7%
2446
16th to endNight
29%48%31%23%3
2708
November1st to 15thNight
35%412%26%17%3
2860
16th to endNight
40%415%26%11%1
3037
December1st to 15thNight
49%7%18%17%6%
3150
16th to endNight
58%5%14%16%3
3259

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
25%420%28%16%5%
225
16th to endDay
29%319%32%12%1
240
February1st to 15thDay
28%6%26%24%12%2
225
16th to endDay
16%7%37%28%8%
373
March1st to 15thDay
17%7%31%32%10%
450
16th to endDay
20%8%31%29%9%
480
April1st to 15thDay
20%10%30%26%11%
449
16th to endDay
14%10%33%22%15%2
438
May1st to 15thDay
11%8%28%30%18%1
468
16th to endDay
12%8%21%33%19%4
522
June1st to 15thDay
5%5%21%38%25%3
615
16th to endDay
3224%39%26%3
570
July1st to 15thDay
2116%45%30%3
425
16th to endDay
5%114%51%23%2
455
August1st to 15thDay
5%118%48%23%2
419
16th to endDay
3113%44%31%5%
460
September1st to 15thDay
5%121%33%29%8%
435
16th to endDay
10%420%34%27%3
435
October1st to 15thDay
13%5%29%28%19%4
299
16th to endDay
9%6%21%36%22%3
240
November1st to 15thDay
12%416%36%21%8%
225
16th to endDay
25%8%17%28%16%4
225
December1st to 15thDay
18%222%40%11%4
225
16th to endDay
23%321%42%7%1
240
January1st to 15thNight
21%216%36%20%2
900
16th to endNight
23%215%36%16%4
960
February1st to 15thNight
21%320%38%15%1
884
16th to endNight
16%323%41%14%1
792
March1st to 15thNight
17%417%43%15%1
900
16th to endNight
19%320%39%15%1
960
April1st to 15thNight
19%6%22%35%15%
809
16th to endNight
13%421%37%22%
669
May1st to 15thNight
11%220%39%23%1
675
16th to endNight
15%316%31%31%2
707
June1st to 15thNight
6%416%40%29%1
637
16th to endNight
5%119%36%34%2
472
July1st to 15thNight
4111%41%39%2
517
16th to endNight
6%7%45%39%1
660
August1st to 15thNight
410%48%34%1
620
16th to endNight
5%111%36%42%2
669
September1st to 15thNight
5%112%40%36%4
798
16th to endNight
9%312%33%33%7%
836
October1st to 15thNight
12%216%39%26%2
840
16th to endNight
11%217%36%29%2
896
November1st to 15thNight
13%218%41%22%2
880
16th to endNight
16%318%38%18%4
1012
December1st to 15thNight
21%121%39%15%1
1125
16th to endNight
26%418%38%11%1
1099
Page generated at 2020-06-04 01:18:55. Version ac04

Copyright 2020 A. Danko


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