Stock Dr/Savery
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stock Dr/Savery 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
41%
16005
20%
46934
13%
15963
47%
15963
25%
29586

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
27%
885
14%
2493
9%
882
31%
882
16%
1803
January16th to endNight
29%
768
17%
2496
11%
768
36%
768
15%
1726
February1st to 15thNight
26%
701
9%
2288
8%
700
29%
700
13%
1699
February16th to endNight
24%
632
14%
1947
6%
632
33%
632
17%
1351
March1st to 15thNight
34%
720
16%
2028
9%
720
41%
720
22%
1364
March16th to endNight
32%
738
17%
2082
10%
738
40%
738
22%
1399
April1st to 15thNight
33%
539
14%
1798
10%
539
40%
539
19%
1129
April16th to endNight
32%
540
17%
1784
11%
540
41%
540
18%
1143
May1st to 15thNight
40%
540
19%
1545
11%
540
46%
540
22%
999
May16th to endNight
46%
563
20%
1498
11%
561
53%
561
26%
945
June1st to 15thNight
47%
540
21%
1440
12%
540
54%
540
38%
797
June16th to endNight
57%
540
30%
1440
18%
540
67%
540
48%
714
July1st to 15thNight
67%
510
21%
1360
17%
510
69%
510
45%
741
July16th to endNight
68%
564
25%
1507
20%
531
75%
531
44%
792
August1st to 15thNight
69%
539
25%
1611
21%
536
72%
536
43%
823
August16th to endNight
73%
573
33%
1869
31%
573
80%
573
45%
885
September1st to 15thNight
63%
540
29%
1800
28%
540
71%
540
39%
903
September16th to endNight
62%
602
34%
1872
25%
602
70%
602
45%
916
October1st to 15thNight
49%
660
25%
1980
18%
660
54%
660
32%
1159
October16th to endNight
49%
704
28%
2112
16%
704
57%
704
32%
1226
November1st to 15thNight
38%
847
22%
2256
12%
847
43%
847
29%
1431
November16th to endNight
30%
900
20%
2520
10%
900
37%
900
24%
1629
December1st to 15thNight
20%
900
8%
2520
4%
900
23%
900
14%
1890
December16th to endNight
20%
960
10%
2688
6%
960
23%
960
12%
2122

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
7%9%35%5%2445%6%44%
47958
Night
7%10%36%423446%45%
47114
TransparencyDay
38%5%12%21%15%6%
47640
Night
38%5%13%22%15%5%
46934
SeeingDay
11%23%27%22%12%2
5889
Night
11%22%20%29%15%2
16010

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
8%17%6%9%5%1333433%
1456
16th to endDay
8%18%7%10%5%2223435%
1728
February1st to 15thDay
10%18%8%10%414435%29%
1575
16th to endDay
6%20%8%9%424445%28%
1527
March1st to 15thDay
5%13%5%8%5%24346%39%
1929
16th to endDay
5%16%6%6%5%24447%35%
2140
April1st to 15thDay
7%14%45%6%25%45%6%35%
2150
16th to endDay
8%15%37%5%35%5%5%6%33%
2174
May1st to 15thDay
10%10%36%5%245%6%6%37%
2403
16th to endDay
9%7%25%5%36%46%8%37%
2616
June1st to 15thDay
6%4244245%6%8%51%
2520
16th to endDay
112313346%69%
2520
July1st to 15thDay
4313336%5%7%8%54%
2520
16th to endDay
33246%35%5%6%8%50%
2555
August1st to 15thDay
43245%36%6%6%8%47%
2340
16th to endDay
43133235%6%8%58%
2333
September1st to 15thDay
5%41342345%7%57%
2160
16th to endDay
7%413313345%60%
1898
October1st to 15thDay
9%7%24433346%48%
1650
16th to endDay
11%10%34413337%47%
1760
November1st to 15thDay
10%9%44223348%45%
1588
16th to endDay
6%11%47%5%32346%44%
1440
December1st to 15thDay
11%17%6%10%7%23435%26%
1440
16th to endDay
10%21%7%11%6%2323425%
1536
January1st to 15thNight
8%20%5%7%5%2223437%
2493
16th to endNight
8%18%7%8%42222338%
2496
February1st to 15thNight
8%15%7%10%5%33335%31%
2277
16th to endNight
6%16%7%8%5%23346%35%
1947
March1st to 15thNight
7%12%47%424445%42%
2028
16th to endNight
5%12%35%5%35%5%5%6%40%
2082
April1st to 15thNight
7%12%35%425%446%42%
1798
16th to endNight
10%12%35%42345%5%41%
1784
May1st to 15thNight
9%9%25%435%5%46%43%
1544
16th to endNight
7%6%15%445%5%6%9%43%
1497
June1st to 15thNight
43133245%6%8%56%
1440
16th to endNight
223312345%70%
1440
July1st to 15thNight
33132235%7%10%57%
1440
16th to endNight
1213435%5%6%8%57%
1611
August1st to 15thNight
241233446%10%56%
1620
16th to endNight
221232446%9%61%
1869
September1st to 15thNight
431333345%7%59%
1800
16th to endNight
7%4121335%5%64%
1872
October1st to 15thNight
9%7%2431345%5%52%
1980
16th to endNight
7%9%24313445%53%
2112
November1st to 15thNight
8%10%35%31345%5%48%
2256
16th to endNight
6%12%5%6%323346%44%
2520
December1st to 15thNight
12%15%6%8%5%33345%31%
2520
16th to endNight
9%20%7%11%5%1333427%
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
54%7%18%12%6%1
1457
16th to endDay
54%315%17%7%1
1728
February1st to 15thDay
56%6%15%14%6%
1575
16th to endDay
56%5%16%15%41
1527
March1st to 15thDay
45%416%22%9%
1929
16th to endDay
47%7%13%22%8%1
2140
April1st to 15thDay
47%5%14%17%12%2
2150
16th to endDay
48%5%11%25%7%
2174
May1st to 15thDay
44%5%11%23%14%
2403
16th to endDay
40%5%14%25%13%
2620
June1st to 15thDay
28%5%11%21%24%9%
2520
16th to endDay
15%35%18%36%20%
2520
July1st to 15thDay
24%6%11%16%21%19%
2371
16th to endDay
29%411%20%16%16%
2396
August1st to 15thDay
29%6%13%18%18%14%
2325
16th to endDay
21%5%10%27%25%10%
2333
September1st to 15thDay
25%48%19%25%15%
2160
16th to endDay
25%39%30%26%4
1898
October1st to 15thDay
36%314%28%14%2
1650
16th to endDay
38%413%28%13%1
1760
November1st to 15thDay
37%5%13%24%15%2
1588
16th to endDay
42%418%22%11%
1440
December1st to 15thDay
60%5%17%12%3
1440
16th to endDay
64%5%9%14%41
1536
January1st to 15thNight
52%5%15%18%6%2
2493
16th to endNight
51%313%18%10%1
2496
February1st to 15thNight
56%6%13%16%7%
2288
16th to endNight
49%415%20%7%1
1947
March1st to 15thNight
42%5%17%21%10%1
2028
16th to endNight
42%6%15%26%8%1
2082
April1st to 15thNight
40%5%15%20%14%2
1798
16th to endNight
42%5%15%23%12%
1784
May1st to 15thNight
38%6%13%23%15%1
1545
16th to endNight
33%7%13%28%15%1
1498
June1st to 15thNight
22%6%14%24%23%8%
1440
16th to endNight
15%3418%29%27%
1440
July1st to 15thNight
20%6%12%20%20%19%
1360
16th to endNight
21%412%22%18%19%
1507
August1st to 15thNight
21%5%13%23%18%16%
1611
16th to endNight
17%5%10%20%31%13%
1869
September1st to 15thNight
23%5%9%19%26%15%
1800
16th to endNight
21%38%29%30%6%
1872
October1st to 15thNight
32%5%11%29%16%4
1980
16th to endNight
32%412%32%17%1
2112
November1st to 15thNight
35%5%13%23%18%2
2256
16th to endNight
40%414%27%11%1
2520
December1st to 15thNight
55%5%17%15%6%
2520
16th to endNight
61%5%12%14%41
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
30%12%24%14%17%1
90
16th to endDay
17%12%31%32%6%
96
February1st to 15thDay
24%25%21%27%1
90
16th to endDay
24%23%23%22%6%
81
March1st to 15thDay
15%37%26%16%2
219
16th to endDay
13%39%31%11%3
288
April1st to 15thDay
14%38%27%13%4
269
16th to endDay
24%36%21%14%3
270
May1st to 15thDay
14%30%26%16%10%1
360
16th to endDay
17%23%23%20%12%2
517
June1st to 15thDay
5%25%24%23%17%3
495
16th to endDay
222%28%25%17%3
495
July1st to 15thDay
5%14%23%28%24%4
475
16th to endDay
5%16%26%30%17%3
414
August1st to 15thDay
5%15%40%25%11%2
315
16th to endDay
311%26%38%15%3
332
September1st to 15thDay
6%23%30%25%10%3
315
16th to endDay
9%17%31%24%11%5%
216
October1st to 15thDay
13%13%33%25%13%1
90
16th to endDay
21%18%20%29%7%2
96
November1st to 15thDay
128%28%21%17%2
90
16th to endDay
16%30%43%10%
90
December1st to 15thDay
22%27%28%18%2
90
16th to endDay
19%21%35%18%4
96
January1st to 15thNight
16%25%23%23%8%2
887
16th to endNight
17%25%20%30%5%
768
February1st to 15thNight
13%25%25%28%6%
704
16th to endNight
13%26%28%25%5%
632
March1st to 15thNight
12%26%21%27%10%1
720
16th to endNight
9%25%27%29%7%1
738
April1st to 15thNight
10%27%23%28%8%
539
16th to endNight
14%27%20%24%11%
540
May1st to 15thNight
13%21%19%29%13%1
540
16th to endNight
11%21%15%30%17%3
563
June1st to 15thNight
5%22%19%33%17%1
540
16th to endNight
319%16%38%21%
540
July1st to 15thNight
6%13%9%27%40%2
510
16th to endNight
217%5%38%34%2
564
August1st to 15thNight
310%11%36%36%1
539
16th to endNight
29%7%32%40%6%
573
September1st to 15thNight
410%16%36%26%6%
540
16th to endNight
7%11%16%27%27%9%
602
October1st to 15thNight
11%15%17%35%15%3
660
16th to endNight
11%16%18%32%16%3
704
November1st to 15thNight
11%23%22%26%13%1
847
16th to endNight
11%28%24%28%5%
900
December1st to 15thNight
17%28%26%23%3
900
16th to endNight
15%31%24%21%5%1
960
Page generated at 2017-09-23 04:43:47. Version ac04

Copyright 2017 A. Danko


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