Spanish Fork
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Spanish Fork 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
62%
16380
22%
49108
20%
16344
64%
16344
33%
29154

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
53%
776
14%
2522
14%
776
55%
776
21%
1704
January16th to endNight
56%
832
18%
2704
19%
832
57%
832
22%
1820
February1st to 15thNight
54%
756
14%
2470
16%
756
55%
756
23%
1631
February16th to endNight
50%
632
20%
1909
19%
632
53%
632
25%
1258
March1st to 15thNight
59%
720
21%
2007
18%
720
62%
720
34%
1239
March16th to endNight
55%
768
19%
2112
15%
768
57%
768
30%
1374
April1st to 15thNight
53%
646
18%
1884
14%
646
54%
646
30%
1161
April16th to endNight
56%
540
24%
1620
18%
540
59%
540
32%
963
May1st to 15thNight
58%
540
23%
1620
18%
540
61%
540
35%
937
May16th to endNight
66%
561
20%
1685
19%
561
68%
561
36%
954
June1st to 15thNight
65%
540
22%
1620
21%
540
70%
540
46%
811
June16th to endNight
71%
540
29%
1620
26%
540
77%
540
61%
713
July1st to 15thNight
76%
510
18%
1530
17%
510
78%
510
41%
823
July16th to endNight
76%
564
21%
1593
20%
531
76%
531
36%
907
August1st to 15thNight
75%
539
26%
1611
21%
536
78%
536
44%
845
August16th to endNight
78%
573
35%
1741
31%
573
79%
573
48%
867
September1st to 15thNight
78%
681
30%
1941
24%
681
83%
681
55%
955
September16th to endNight
76%
716
38%
1980
32%
716
78%
716
53%
1011
October1st to 15thNight
68%
720
29%
2100
24%
720
72%
720
44%
1140
October16th to endNight
70%
768
34%
2304
30%
768
74%
768
42%
1237
November1st to 15thNight
63%
760
26%
2455
27%
760
66%
760
35%
1384
November16th to endNight
59%
832
25%
2587
25%
832
61%
832
32%
1535
December1st to 15thNight
53%
975
14%
2730
12%
975
55%
975
28%
1818
December16th to endNight
43%
891
13%
2763
13%
891
44%
891
16%
2067

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
6%6%2442445%7%50%
48960
Night
7%7%2442345%6%50%
49302
TransparencyDay
33%410%19%19%11%
48655
Night
34%411%21%18%9%
49108
SeeingDay
10%11%27%32%14%4
5772
Night
10%315%39%26%3
16390

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
11%14%35%425%346%38%
1746
16th to endDay
10%14%5%7%422345%38%
1872
February1st to 15thDay
11%13%46%42435%7%35%
1693
16th to endDay
8%13%45%5%25%45%6%37%
1564
March1st to 15thDay
5%8%445%3445%7%46%
1952
16th to endDay
8%11%36%6%2445%7%37%
2112
April1st to 15thDay
8%9%35%5%3445%6%43%
2060
16th to endDay
7%8%25%43345%6%46%
2340
May1st to 15thDay
7%5%243245%6%7%49%
2331
16th to endDay
6%5%2443447%9%46%
2429
June1st to 15thDay
431343435%7%57%
2340
16th to endDay
21121223475%
2340
July1st to 15thDay
22134245%6%8%57%
2340
16th to endDay
3313335%5%6%8%55%
2467
August1st to 15thDay
33134246%6%9%55%
2340
16th to endDay
2133245%6%7%61%
2459
September1st to 15thDay
321232345%6%63%
2017
16th to endDay
5%213323336%66%
1980
October1st to 15thDay
7%42442335%6%55%
1858
16th to endDay
7%5%12314347%57%
1920
November1st to 15thDay
11%7%24324335%50%
1733
16th to endDay
8%8%35%42335%8%46%
1687
December1st to 15thDay
10%11%5%7%423445%40%
1560
16th to endDay
14%14%49%5%2335%7%28%
1820
January1st to 15thNight
12%11%36%5%23346%39%
2522
16th to endNight
11%12%5%5%423346%39%
2704
February1st to 15thNight
10%10%36%42345%6%41%
2459
16th to endNight
7%10%47%42346%7%41%
1909
March1st to 15thNight
7%9%4332335%8%46%
2007
16th to endNight
8%10%25%425%45%8%43%
2112
April1st to 15thNight
10%8%24424336%48%
1884
16th to endNight
8%6%24424447%50%
1620
May1st to 15thNight
7%4145%2446%7%50%
1619
16th to endNight
7%3234346%6%6%51%
1684
June1st to 15thNight
5%222324447%61%
1620
16th to endNight
111222345%73%
1620
July1st to 15thNight
2213436%7%6%9%52%
1620
16th to endNight
2315%5%46%6%6%6%52%
1701
August1st to 15thNight
32135%3446%9%55%
1620
16th to endNight
22134335%5%8%60%
1741
September1st to 15thNight
2212322446%67%
1941
16th to endNight
6%212212335%68%
1980
October1st to 15thNight
6%413213345%60%
2100
16th to endNight
6%5%13312347%58%
2304
November1st to 15thNight
8%7%1432335%6%53%
2455
16th to endNight
8%8%35%323346%50%
2587
December1st to 15thNight
11%11%45%423335%44%
2730
16th to endNight
15%16%6%8%42333431%
2763

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
46%6%19%20%7%
1747
16th to endDay
46%8%14%19%9%2
1872
February1st to 15thDay
49%5%15%18%9%1
1693
16th to endDay
47%5%13%22%11%
1564
March1st to 15thDay
38%6%14%23%14%2
1952
16th to endDay
46%412%23%10%3
2112
April1st to 15thDay
41%411%21%16%3
2060
16th to endDay
37%5%10%22%20%3
2340
May1st to 15thDay
32%5%9%21%24%6%
2331
16th to endDay
33%5%11%21%23%4
2432
June1st to 15thDay
24%47%14%33%16%
2340
16th to endDay
14%138%28%43%
2340
July1st to 15thDay
23%47%13%18%32%
2201
16th to endDay
25%5%9%12%20%26%
2312
August1st to 15thDay
25%48%16%18%25%
2325
16th to endDay
21%37%16%29%21%
2459
September1st to 15thDay
22%38%13%28%23%
2017
16th to endDay
21%36%20%30%17%
1980
October1st to 15thDay
30%47%21%29%5%
1858
16th to endDay
27%310%29%24%4
1920
November1st to 15thDay
36%410%24%19%4
1733
16th to endDay
34%6%15%28%12%2
1687
December1st to 15thDay
45%417%23%8%
1560
16th to endDay
55%5%14%17%7%
1820
January1st to 15thNight
46%7%18%21%6%1
2522
16th to endNight
45%6%15%20%9%2
2704
February1st to 15thNight
43%6%17%20%10%
2470
16th to endNight
42%5%11%27%11%
1909
March1st to 15thNight
35%414%28%14%2
2007
16th to endNight
38%6%12%25%14%3
2112
April1st to 15thNight
37%312%22%19%4
1884
16th to endNight
34%5%11%26%20%2
1620
May1st to 15thNight
32%49%21%24%7%
1620
16th to endNight
29%5%11%26%22%4
1685
June1st to 15thNight
21%48%17%33%14%
1620
16th to endNight
14%1410%26%42%
1620
July1st to 15thNight
26%47%12%17%30%
1530
16th to endNight
29%6%8%12%18%25%
1593
August1st to 15thNight
25%410%20%15%24%
1611
16th to endNight
21%49%14%28%22%
1741
September1st to 15thNight
18%27%17%26%26%
1941
16th to endNight
20%25%20%28%21%
1980
October1st to 15thNight
26%38%24%27%9%
2100
16th to endNight
25%47%27%29%4
2304
November1st to 15thNight
31%410%25%20%6%
2455
16th to endNight
35%411%28%16%3
2587
December1st to 15thNight
42%5%17%25%9%
2730
16th to endNight
57%5%13%17%6%
2763

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
29%5%11%31%15%6%
135
16th to endDay
18%6%13%36%18%5%
144
February1st to 15thDay
16%6%18%39%14%4
130
16th to endDay
8%17%35%28%7%1
223
March1st to 15thDay
10%17%31%28%10%1
270
16th to endDay
18%20%33%24%21
288
April1st to 15thDay
11%24%27%21%11%4
269
16th to endDay
18%25%26%22%5%1
270
May1st to 15thDay
11%17%36%24%7%2
288
16th to endDay
12%14%25%27%16%3
330
June1st to 15thDay
6%19%32%26%12%3
315
16th to endDay
210%31%36%13%4
315
July1st to 15thDay
26%27%38%17%6%
305
16th to endDay
4131%43%15%2
327
August1st to 15thDay
7%427%39%15%5%
315
16th to endDay
3327%38%21%6%
332
September1st to 15thDay
48%30%34%14%7%
315
16th to endDay
9%9%20%32%21%6%
315
October1st to 15thDay
313%31%25%17%8%
193
16th to endDay
9%6%22%33%23%4
144
November1st to 15thDay
10%11%15%33%20%8%
135
16th to endDay
17%12%14%34%18%2
135
December1st to 15thDay
15%5%22%34%16%5%
135
16th to endDay
15%416%45%16%
144
January1st to 15thNight
16%315%37%21%5%
780
16th to endNight
16%413%37%24%3
832
February1st to 15thNight
15%215%45%16%3
760
16th to endNight
12%325%41%15%1
632
March1st to 15thNight
12%5%16%43%20%1
720
16th to endNight
11%6%20%42%16%2
768
April1st to 15thNight
15%7%19%39%16%1
646
16th to endNight
12%7%19%38%20%2
540
May1st to 15thNight
10%319%40%23%2
540
16th to endNight
9%414%40%28%3
563
June1st to 15thNight
7%417%41%27%2
540
16th to endNight
3218%39%33%2
540
July1st to 15thNight
410%34%44%5%
510
16th to endNight
48%36%44%4
564
August1st to 15thNight
5%11%45%35%2
539
16th to endNight
319%36%44%4
573
September1st to 15thNight
4110%37%38%8%
681
16th to endNight
8%28%31%37%11%
716
October1st to 15thNight
7%316%41%26%5%
720
16th to endNight
8%313%39%29%5%
768
November1st to 15thNight
10%315%37%28%3
760
16th to endNight
11%5%18%37%22%5%
832
December1st to 15thNight
15%417%43%16%2
975
16th to endNight
21%5%15%39%15%2
891
Page generated at 2018-02-15 08:58:45. Version ac04

Copyright 2018 A. Danko


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