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 2018-02-14.

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
58%
16282
21%
48739
18%
16245
61%
16245
30%
30212

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
49%
776
10%
2522
10%
776
50%
776
17%
1817
January16th to endNight
48%
832
12%
2704
13%
832
50%
832
16%
1969
February1st to 15thNight
49%
755
12%
2470
13%
754
51%
754
19%
1746
February16th to endNight
47%
632
17%
1911
16%
632
50%
632
22%
1294
March1st to 15thNight
55%
720
19%
2025
17%
720
58%
720
27%
1349
March16th to endNight
48%
768
17%
2112
13%
768
51%
768
26%
1455
April1st to 15thNight
48%
647
17%
1856
13%
647
51%
647
27%
1202
April16th to endNight
54%
540
24%
1620
19%
540
56%
540
28%
1032
May1st to 15thNight
58%
539
22%
1619
18%
539
61%
539
33%
954
May16th to endNight
60%
561
17%
1685
16%
561
61%
561
29%
1051
June1st to 15thNight
67%
540
22%
1467
19%
540
70%
540
46%
799
June16th to endNight
71%
404
32%
1363
35%
404
79%
404
62%
540
July1st to 15thNight
74%
439
19%
1459
21%
439
76%
439
42%
735
July16th to endNight
79%
564
26%
1593
24%
531
80%
531
49%
797
August1st to 15thNight
76%
539
28%
1611
24%
536
78%
536
47%
822
August16th to endNight
78%
573
36%
1722
30%
573
80%
573
49%
862
September1st to 15thNight
74%
684
28%
1944
23%
684
77%
684
48%
1013
September16th to endNight
73%
716
35%
1980
29%
716
75%
716
51%
1034
October1st to 15thNight
66%
720
27%
2097
23%
720
69%
720
41%
1173
October16th to endNight
65%
768
33%
2322
29%
768
68%
768
39%
1298
November1st to 15thNight
58%
760
22%
2470
22%
760
61%
760
29%
1497
November16th to endNight
55%
878
19%
2633
18%
878
57%
878
27%
1668
December1st to 15thNight
47%
975
11%
2730
9%
975
48%
975
22%
1934
December16th to endNight
38%
952
11%
2824
9%
952
40%
952
14%
2171

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
10%7%2442345%6%48%
49310
Night
11%7%24423446%47%
48933
TransparencyDay
35%6%11%18%18%10%
49004
Night
37%5%11%20%16%8%
48740
SeeingDay
11%5%22%36%20%3
6035
Night
14%216%38%24%2
16294

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
16%13%37%435%5%45%29%
1746
16th to endDay
15%14%5%45%35%5%6%5%29%
1872
February1st to 15thDay
16%14%35%4335%5%6%30%
1693
16th to endDay
12%15%5%6%5%3446%6%29%
1560
March1st to 15thDay
9%9%35%425%5%6%7%38%
1935
16th to endDay
15%10%35%435%5%6%7%31%
2112
April1st to 15thDay
14%8%245%345%5%8%38%
2089
16th to endDay
11%9%35%424447%42%
2340
May1st to 15thDay
8%6%244245%5%8%44%
2331
16th to endDay
12%424425%5%5%8%43%
2429
June1st to 15thDay
6%42442345%8%52%
2487
16th to endDay
42111123475%
2584
July1st to 15thDay
321332335%7%63%
2406
16th to endDay
421231345%6%64%
2467
August1st to 15thDay
3212323446%64%
2340
16th to endDay
3212313346%66%
2480
September1st to 15thDay
4213323345%64%
2014
16th to endDay
7%212222346%65%
1980
October1st to 15thDay
11%413423446%51%
1863
16th to endDay
8%6%13423447%52%
1899
November1st to 15thDay
14%8%24423347%44%
1719
16th to endDay
14%8%34423447%41%
1642
December1st to 15thDay
15%12%37%5%35%44433%
1560
16th to endDay
18%17%47%434336%26%
1762
January1st to 15thNight
18%9%36%5%33336%36%
2522
16th to endNight
15%13%35%433445%34%
2704
February1st to 15thNight
15%11%35%5%34445%36%
2459
16th to endNight
11%11%45%5%2245%6%38%
1911
March1st to 15thNight
12%10%34423447%41%
2025
16th to endNight
11%11%35%5%24446%40%
2112
April1st to 15thNight
12%9%35%5%2434445%
1856
16th to endNight
12%6%25%42445%6%45%
1620
May1st to 15thNight
9%5%1442445%6%50%
1619
16th to endNight
12%42442445%7%46%
1684
June1st to 15thNight
6%21322345%7%58%
1467
16th to endNight
31221123475%
1363
July1st to 15thNight
3413425%5%6%7%56%
1548
16th to endNight
331322345%7%60%
1701
August1st to 15thNight
32144335%5%7%59%
1620
16th to endNight
331232445%6%62%
1722
September1st to 15thNight
4312414445%63%
1944
16th to endNight
7%21231223466%
1980
October1st to 15thNight
9%422222346%57%
2097
16th to endNight
9%414323336%56%
2322
November1st to 15thNight
12%7%24423346%48%
2470
16th to endNight
11%8%245%34346%44%
2633
December1st to 15thNight
15%9%37%42335%6%38%
2730
16th to endNight
21%14%46%5%23345%27%
2824

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%11%18%12%2
1747
16th to endDay
54%10%19%12%3
1872
February1st to 15thDay
54%9%14%14%7%
1693
16th to endDay
52%8%15%17%41
1560
March1st to 15thDay
41%10%15%21%10%
1935
16th to endDay
49%6%14%19%7%1
2112
April1st to 15thDay
42%7%13%21%13%1
2089
16th to endDay
40%6%8%23%18%1
2340
May1st to 15thDay
33%7%9%25%19%4
2331
16th to endDay
36%7%9%22%20%3
2432
June1st to 15thDay
27%5%8%19%28%9%
2487
16th to endDay
13%249%31%38%
2584
July1st to 15thDay
19%36%14%23%31%
2266
16th to endDay
19%46%11%24%34%
2312
August1st to 15thDay
17%47%14%24%31%
2325
16th to endDay
17%36%16%31%24%
2480
September1st to 15thDay
21%47%15%28%22%
2014
16th to endDay
20%38%22%34%9%
1980
October1st to 15thDay
32%5%10%26%19%4
1863
16th to endDay
30%6%13%30%18%1
1899
November1st to 15thDay
40%7%14%22%15%
1719
16th to endDay
42%5%19%22%9%
1642
December1st to 15thDay
53%9%17%13%5%
1560
16th to endDay
60%8%13%11%41
1762
January1st to 15thNight
50%8%19%16%3
2522
16th to endNight
50%9%16%16%5%1
2704
February1st to 15thNight
48%8%15%18%8%
2470
16th to endNight
45%6%13%26%6%
1911
March1st to 15thNight
42%5%13%25%12%
2025
16th to endNight
44%5%12%23%10%2
2112
April1st to 15thNight
42%312%25%13%3
1856
16th to endNight
39%6%9%23%19%3
1620
May1st to 15thNight
32%6%8%22%23%6%
1620
16th to endNight
36%7%10%21%19%4
1685
June1st to 15thNight
23%411%19%30%9%
1467
16th to endNight
13%15%11%27%41%
1363
July1st to 15thNight
24%47%11%21%30%
1459
16th to endNight
21%46%11%22%33%
1593
August1st to 15thNight
22%47%13%20%31%
1611
16th to endNight
20%46%12%29%26%
1722
September1st to 15thNight
23%37%13%25%27%
1944
16th to endNight
21%36%18%31%18%
1980
October1st to 15thNight
27%49%27%23%6%
2097
16th to endNight
29%47%30%24%3
2322
November1st to 15thNight
38%412%24%17%3
2470
16th to endNight
40%5%15%26%10%1
2633
December1st to 15thNight
47%7%18%19%6%
2730
16th to endNight
59%5%14%15%3
2824

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
28%117%27%17%8%
135
16th to endDay
27%313%36%15%2
144
February1st to 15thDay
30%219%26%17%3
130
16th to endDay
19%9%35%25%9%1
219
March1st to 15thDay
15%7%27%35%12%
270
16th to endDay
19%7%33%29%9%
288
April1st to 15thDay
14%10%33%23%17%1
269
16th to endDay
17%11%35%21%14%
270
May1st to 15thDay
10%10%33%29%14%
288
16th to endDay
11%7%21%34%20%4
330
June1st to 15thDay
6%5%22%39%23%2
462
16th to endDay
4120%39%29%4
430
July1st to 15thDay
217%47%29%2
305
16th to endDay
3215%53%22%2
327
August1st to 15thDay
4219%50%20%3
315
16th to endDay
4210%44%32%5%
332
September1st to 15thDay
4223%35%26%7%
315
16th to endDay
10%216%35%29%4
315
October1st to 15thDay
13%428%29%19%5%
198
16th to endDay
13%218%36%25%4
144
November1st to 15thDay
17%316%32%18%11%
135
16th to endDay
22%10%17%32%14%2
135
December1st to 15thDay
15%222%40%12%5%
135
16th to endDay
25%218%43%9%1
144
January1st to 15thNight
22%115%36%21%2
780
16th to endNight
23%215%34%19%4
832
February1st to 15thNight
20%218%40%17%1
760
16th to endNight
16%323%39%15%1
632
March1st to 15thNight
15%317%43%16%2
720
16th to endNight
17%322%40%15%1
768
April1st to 15thNight
16%6%23%34%17%
647
16th to endNight
14%420%37%22%
540
May1st to 15thNight
12%320%40%22%2
540
16th to endNight
14%215%32%33%2
563
June1st to 15thNight
7%5%17%41%27%
540
16th to endNight
4117%36%36%2
404
July1st to 15thNight
4112%40%39%2
439
16th to endNight
6%7%43%40%1
564
August1st to 15thNight
410%47%35%1
539
16th to endNight
5%110%34%46%2
573
September1st to 15thNight
5%112%39%36%3
684
16th to endNight
9%211%30%36%8%
716
October1st to 15thNight
12%214%38%28%2
720
16th to endNight
11%215%36%31%2
768
November1st to 15thNight
15%217%38%22%3
760
16th to endNight
14%319%39%19%4
878
December1st to 15thNight
20%220%39%16%1
975
16th to endNight
27%418%36%11%1
952
Page generated at 2018-02-15 08:58:46. Version ac04

Copyright 2018 A. Danko


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