Turlock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Turlock clear sky chart from 2005-11-05 to 2017-09-17.

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
71%
15379
31%
46891
27%
15340
75%
15340
48%
23347

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
63%
717
20%
2443
20%
716
67%
716
32%
1372
January16th to endNight
63%
768
25%
2496
26%
768
66%
768
32%
1459
February1st to 15thNight
61%
699
25%
2238
26%
698
66%
698
33%
1296
February16th to endNight
58%
632
27%
1895
25%
632
64%
632
33%
1117
March1st to 15thNight
60%
720
21%
2066
20%
720
64%
720
34%
1266
March16th to endNight
57%
768
23%
2049
16%
768
63%
768
39%
1220
April1st to 15thNight
56%
719
26%
1799
13%
719
62%
719
40%
1093
April16th to endNight
60%
720
29%
1800
12%
720
66%
720
55%
954
May1st to 15thNight
71%
642
31%
1722
20%
642
75%
642
64%
814
May16th to endNight
71%
375
35%
1496
35%
374
80%
374
56%
546
June1st to 15thNight
73%
360
32%
1440
34%
360
82%
360
60%
510
June16th to endNight
87%
360
40%
1440
50%
360
91%
360
81%
422
July1st to 15thNight
93%
340
36%
1360
47%
340
95%
340
79%
399
July16th to endNight
87%
529
38%
1558
34%
496
89%
496
70%
618
August1st to 15thNight
91%
610
40%
1683
29%
607
92%
607
84%
672
August16th to endNight
93%
764
46%
1910
29%
764
93%
764
87%
818
September1st to 15thNight
90%
720
43%
1800
31%
720
93%
720
83%
803
September16th to endNight
85%
664
47%
1790
41%
664
90%
664
78%
768
October1st to 15thNight
75%
660
33%
1980
33%
660
81%
660
55%
936
October16th to endNight
77%
704
40%
2112
41%
704
82%
704
59%
960
November1st to 15thNight
74%
700
32%
2239
33%
700
79%
700
49%
1075
November16th to endNight
69%
720
28%
2367
27%
720
73%
720
41%
1205
December1st to 15thNight
63%
720
22%
2520
20%
720
69%
720
29%
1450
December16th to endNight
53%
768
22%
2688
20%
768
60%
768
27%
1574

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%312212335%66%
47890
Night
7%212212335%66%
47079
TransparencyDay
20%38%19%25%21%
47573
Night
21%39%20%24%20%
46895
SeeingDay
7%414%25%29%19%
5921
Night
8%213%37%33%4
15388

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
13%7%35%3345%47%41%
1493
16th to endDay
15%8%36%5%25%346%38%
1728
February1st to 15thDay
15%5%34424446%45%
1622
16th to endDay
16%41442425%7%45%
1579
March1st to 15thDay
10%423425%5%49%47%
1893
16th to endDay
9%4234245%5%7%49%
2175
April1st to 15thDay
10%424423347%51%
2149
16th to endDay
6%212222335%67%
2160
May1st to 15thDay
2112111335%75%
2226
16th to endDay
312212345%71%
2615
June1st to 15thDay
22121222475%
2520
16th to endDay
111288%
2520
July1st to 15thDay
112388%
2520
16th to endDay
1111121385%
2500
August1st to 15thDay
111111188%
2268
16th to endDay
112387%
2292
September1st to 15thDay
111387%
2160
16th to endDay
2111122382%
1872
October1st to 15thDay
2112212246%72%
1650
16th to endDay
5%23212236%66%
1760
November1st to 15thDay
6%313324447%59%
1620
16th to endDay
10%7%34334247%49%
1592
December1st to 15thDay
13%8%35%5%24445%41%
1440
16th to endDay
18%6%35%423437%40%
1536
January1st to 15thNight
12%5%24212347%51%
2443
16th to endNight
15%413323446%49%
2496
February1st to 15thNight
13%5%1442335%7%49%
2230
16th to endNight
15%323313347%51%
1895
March1st to 15thNight
12%424324346%50%
2066
16th to endNight
11%31341345%7%53%
2049
April1st to 15thNight
9%32332345%7%53%
1799
16th to endNight
4112312336%68%
1800
May1st to 15thNight
2111212235%75%
1722
16th to endNight
311112236%75%
1496
June1st to 15thNight
211112215%79%
1440
16th to endNight
111289%
1440
July1st to 15thNight
1121386%
1440
16th to endNight
11111112282%
1665
August1st to 15thNight
111111288%
1692
16th to endNight
112288%
1910
September1st to 15thNight
1111288%
1800
16th to endNight
1111112385%
1790
October1st to 15thNight
42221233471%
1980
16th to endNight
5%1211233473%
2112
November1st to 15thNight
7%212212246%66%
2239
16th to endNight
8%313324337%58%
2367
December1st to 15thNight
13%423323447%49%
2520
16th to endNight
18%423323346%48%
2688

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
42%6%12%18%18%1
1493
16th to endDay
46%6%8%17%16%4
1728
February1st to 15thDay
38%6%13%25%13%3
1622
16th to endDay
37%6%13%24%15%1
1579
March1st to 15thDay
32%7%13%25%18%3
1893
16th to endDay
31%7%16%21%19%3
2175
April1st to 15thDay
33%411%26%18%5%
2149
16th to endDay
20%412%26%28%7%
2160
May1st to 15thDay
12%38%25%37%12%
2226
16th to endDay
14%49%28%30%12%
2619
June1st to 15thDay
13%38%21%28%24%
2520
16th to endDay
6%212%33%45%
2520
July1st to 15thDay
426%22%63%
2371
16th to endDay
7%137%25%54%
2344
August1st to 15thDay
6%28%29%51%
2252
16th to endDay
429%36%45%
2292
September1st to 15thDay
5%1311%33%44%
2160
16th to endDay
8%1322%39%24%
1872
October1st to 15thDay
13%38%26%26%21%
1650
16th to endDay
20%38%25%28%13%
1760
November1st to 15thDay
25%414%30%23%2
1620
16th to endDay
35%412%25%18%2
1592
December1st to 15thDay
44%6%11%17%16%2
1440
16th to endDay
44%6%14%18%14%2
1536
January1st to 15thNight
32%5%13%25%17%5%
2443
16th to endNight
34%5%13%17%17%11%
2496
February1st to 15thNight
33%5%11%26%17%6%
2241
16th to endNight
33%5%11%27%19%2
1895
March1st to 15thNight
33%6%12%20%19%7%
2066
16th to endNight
28%6%14%21%20%8%
2049
April1st to 15thNight
28%6%11%25%21%6%
1799
16th to endNight
16%5%14%21%30%11%
1800
May1st to 15thNight
12%37%22%34%19%
1723
16th to endNight
12%39%28%34%13%
1496
June1st to 15thNight
10%29%20%30%25%
1440
16th to endNight
41210%29%52%
1440
July1st to 15thNight
5%26%19%65%
1360
16th to endNight
8%236%22%56%
1558
August1st to 15thNight
5%1211%26%52%
1683
16th to endNight
4210%32%49%
1910
September1st to 15thNight
5%1310%28%49%
1800
16th to endNight
8%1219%39%29%
1790
October1st to 15thNight
16%48%22%26%22%
1980
16th to endNight
14%37%22%32%19%
2112
November1st to 15thNight
20%311%27%28%7%
2239
16th to endNight
25%411%26%26%5%
2367
December1st to 15thNight
34%5%13%21%18%5%
2520
16th to endNight
36%5%14%21%16%5%
2688

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
23%318%25%14%15%
121
16th to endDay
16%319%18%19%21%
256
February1st to 15thDay
18%5%13%21%21%20%
245
16th to endDay
15%5%22%27%16%12%
238
March1st to 15thDay
12%8%19%24%21%14%
270
16th to endDay
11%8%22%28%19%9%
288
April1st to 15thDay
14%13%25%21%14%10%
269
16th to endDay
8%11%24%31%15%9%
270
May1st to 15thDay
6%6%19%31%25%11%
288
16th to endDay
5%6%15%21%33%16%
330
June1st to 15thDay
4318%32%29%11%
315
16th to endDay
111%28%37%20%
315
July1st to 15thDay
421%37%35%
305
16th to endDay
1317%50%27%
327
August1st to 15thDay
25%23%43%24%
315
16th to endDay
421%41%32%
332
September1st to 15thDay
427%40%26%
315
16th to endDay
238%27%33%25%
260
October1st to 15thDay
3419%27%27%18%
255
16th to endDay
7%312%27%28%19%
272
November1st to 15thDay
7%12%15%30%34%
126
16th to endDay
8%414%36%31%4
85
December1st to 15thDay
26%6%15%31%18%1
60
16th to endDay
15%112%29%29%10%
64
January1st to 15thNight
14%112%32%31%6%
720
16th to endNight
16%111%31%30%8%
768
February1st to 15thNight
14%313%33%29%6%
704
16th to endNight
14%417%37%21%4
632
March1st to 15thNight
12%316%34%28%5%
720
16th to endNight
11%419%36%26%1
768
April1st to 15thNight
9%423%37%23%
719
16th to endNight
4425%34%27%3
720
May1st to 15thNight
2121%43%28%3
643
16th to endNight
3219%41%32%
375
June1st to 15thNight
3220%47%26%
360
16th to endNight
11%51%35%
360
July1st to 15thNight
452%41%1
340
16th to endNight
15%35%53%3
529
August1st to 15thNight
5%47%41%4
610
16th to endNight
442%49%3
764
September1st to 15thNight
15%42%46%3
720
16th to endNight
29%37%43%6%
664
October1st to 15thNight
5%212%37%36%6%
660
16th to endNight
5%211%32%36%11%
704
November1st to 15thNight
8%111%35%37%6%
700
16th to endNight
8%114%37%31%7%
720
December1st to 15thNight
14%212%39%25%5%
720
16th to endNight
18%416%31%26%2
768
Page generated at 2017-09-18 05:38:27. Version ac04

Copyright 2017 A. Danko


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