Lake Somerville State Park - Nails Creek Unit
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Somerville State Park - Nails Creek Unit 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
52%
15434
25%
46980
18%
15388
59%
15388
33%
27359

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
37%
896
25%
2327
11%
895
44%
895
30%
1518
January16th to endNight
36%
960
28%
2496
11%
960
45%
960
32%
1586
February1st to 15thNight
35%
716
26%
2117
12%
709
46%
709
28%
1295
February16th to endNight
27%
584
27%
1846
9%
584
41%
584
27%
1105
March1st to 15thNight
31%
540
26%
1980
14%
540
46%
540
23%
1194
March16th to endNight
36%
576
24%
2112
16%
576
49%
576
27%
1189
April1st to 15thNight
31%
539
22%
1977
12%
539
46%
539
26%
1126
April16th to endNight
34%
540
24%
1802
15%
540
49%
540
29%
1063
May1st to 15thNight
35%
539
21%
1619
15%
539
45%
539
31%
985
May16th to endNight
55%
563
27%
1685
23%
561
65%
561
38%
948
June1st to 15thNight
74%
540
22%
1620
25%
540
78%
540
49%
810
June16th to endNight
78%
540
20%
1620
23%
540
81%
540
38%
932
July1st to 15thNight
79%
510
21%
1530
24%
510
81%
510
43%
829
July16th to endNight
84%
564
21%
1594
25%
531
85%
531
44%
859
August1st to 15thNight
89%
539
28%
1610
32%
536
89%
536
56%
757
August16th to endNight
78%
573
19%
1968
23%
573
79%
573
29%
1152
September1st to 15thNight
79%
540
19%
1980
23%
540
80%
540
32%
1100
September16th to endNight
70%
513
27%
1891
29%
513
72%
513
30%
1049
October1st to 15thNight
71%
561
34%
1881
32%
561
73%
561
43%
942
October16th to endNight
59%
704
35%
2112
24%
704
66%
704
46%
1079
November1st to 15thNight
52%
700
28%
2100
19%
700
58%
700
33%
1241
November16th to endNight
48%
837
30%
2277
17%
837
54%
837
36%
1340
December1st to 15thNight
40%
900
26%
2340
14%
900
45%
900
28%
1585
December16th to endNight
38%
960
22%
2496
10%
960
44%
960
28%
1675

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
11%5%25%5%3445%7%43%
47891
Night
10%424324447%51%
47183
TransparencyDay
38%7%10%18%16%8%
47591
Night
31%6%12%20%18%10%
46988
SeeingDay
10%416%27%30%11%
5421
Night
12%5%24%35%19%1
15439

By Month

Percentage Cloud Cover SE (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
18%6%3342334445%
1611
16th to endDay
17%5%24412245%49%
1728
February1st to 15thDay
16%7%3432223448%
1749
16th to endDay
16%8%26%433335%43%
1625
March1st to 15thDay
21%8%25%324345%39%
1980
16th to endDay
14%7%35%423335%46%
2110
April1st to 15thDay
12%5%36%5%34448%40%
1971
16th to endDay
12%5%36%5%3445%6%42%
2154
May1st to 15thDay
10%6%36%6%35%5%6%7%37%
2331
16th to endDay
11%5%35%6%445%7%8%37%
2430
June1st to 15thDay
33246%47%7%8%9%43%
2340
16th to endDay
6%5%35%6%48%7%8%10%33%
2340
July1st to 15thDay
6%325%7%47%6%8%11%35%
2340
16th to endDay
5%326%7%46%6%7%12%37%
2466
August1st to 15thDay
32143246%5%10%54%
2340
16th to endDay
6%425%6%46%6%8%11%37%
2231
September1st to 15thDay
7%426%6%36%5%5%9%40%
1980
16th to endDay
7%4245%45%6%5%7%44%
1881
October1st to 15thDay
8%42342445%7%51%
1738
16th to endDay
9%31321233463%
1760
November1st to 15thDay
9%6%25%4235%5%7%48%
1758
16th to endDay
14%6%13333335%52%
1680
December1st to 15thDay
19%8%25%5%23335%40%
1620
16th to endDay
17%7%35%5%34345%39%
1728
January1st to 15thNight
16%6%24413335%47%
2327
16th to endNight
17%5%23313336%48%
2496
February1st to 15thNight
14%7%34312235%51%
2114
16th to endNight
13%5%24323335%50%
1846
March1st to 15thNight
17%6%24313336%45%
1980
16th to endNight
10%5%24424446%51%
2112
April1st to 15thNight
8%424425%45%7%47%
1977
16th to endNight
11%5%24423346%49%
1802
May1st to 15thNight
7%326%43446%10%44%
1619
16th to endNight
3313326%5%6%10%51%
1683
June1st to 15thNight
21123235%5%10%61%
1620
16th to endNight
3214325%6%8%10%51%
1620
July1st to 15thNight
5%2123145%6%10%55%
1620
16th to endNight
321332446%13%54%
1702
August1st to 15thNight
21222335%12%62%
1620
16th to endNight
5%314436%5%7%11%45%
1968
September1st to 15thNight
7%314425%5%5%10%50%
1980
16th to endNight
8%31343346%8%50%
1891
October1st to 15thNight
6%313323346%61%
1881
16th to endNight
8%31221233465%
2112
November1st to 15thNight
9%5%24423346%52%
2100
16th to endNight
11%5%23323235%55%
2277
December1st to 15thNight
16%7%34423346%43%
2340
16th to endNight
16%7%24423345%44%
2496

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%45%16%19%11%
1612
16th to endDay
38%35%14%22%14%
1728
February1st to 15thDay
39%46%15%20%13%
1750
16th to endDay
44%37%14%19%11%
1625
March1st to 15thDay
47%5%5%11%20%9%
1980
16th to endDay
41%46%16%24%6%
2112
April1st to 15thDay
42%6%6%17%15%11%
1971
16th to endDay
42%5%7%18%18%8%
2154
May1st to 15thDay
44%7%10%15%14%8%
2331
16th to endDay
41%8%12%18%15%3
2434
June1st to 15thDay
33%9%12%22%18%3
2340
16th to endDay
41%12%12%19%12%1
2340
July1st to 15thDay
37%9%18%23%10%
2201
16th to endDay
33%11%21%24%7%
2311
August1st to 15thDay
24%9%18%31%13%1
2326
16th to endDay
38%12%17%20%8%2
2231
September1st to 15thDay
39%9%13%18%14%5%
1980
16th to endDay
36%7%10%19%17%8%
1881
October1st to 15thDay
32%5%9%17%17%16%
1738
16th to endDay
25%36%16%29%19%
1760
November1st to 15thDay
34%5%10%20%18%10%
1758
16th to endDay
33%48%12%22%18%
1680
December1st to 15thDay
47%47%15%17%8%
1620
16th to endDay
46%5%8%13%17%8%
1728
January1st to 15thNight
40%35%15%20%14%
2327
16th to endNight
37%35%14%22%15%
2496
February1st to 15thNight
38%35%13%20%18%
2124
16th to endNight
37%46%16%19%15%
1846
March1st to 15thNight
39%5%8%14%20%12%
1980
16th to endNight
33%6%10%17%21%10%
2112
April1st to 15thNight
34%6%10%17%18%13%
1977
16th to endNight
36%5%10%20%15%10%
1802
May1st to 15thNight
33%7%13%21%15%9%
1620
16th to endNight
26%7%16%29%16%3
1685
June1st to 15thNight
18%6%16%29%25%3
1620
16th to endNight
25%9%19%29%13%2
1620
July1st to 15thNight
22%7%23%33%11%
1530
16th to endNight
20%9%30%30%8%
1594
August1st to 15thNight
14%5%27%35%15%1
1610
16th to endNight
29%11%23%26%7%2
1968
September1st to 15thNight
28%8%19%23%12%6%
1980
16th to endNight
30%8%13%20%17%10%
1891
October1st to 15thNight
24%411%24%19%15%
1881
16th to endNight
23%36%16%27%22%
2112
November1st to 15thNight
33%5%9%21%20%10%
2100
16th to endNight
31%47%13%22%20%
2277
December1st to 15thNight
41%5%7%18%17%8%
2340
16th to endNight
42%46%15%19%11%
2496

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
17%7%31%32%10%1
90
16th to endDay
16%15%40%17%7%2
96
February1st to 15thDay
11%16%35%24%12%
90
16th to endDay
17%13%39%17%11%1
81
March1st to 15thDay
26%18%31%12%11%
90
16th to endDay
13%8%31%30%14%2
96
April1st to 15thDay
10%13%34%24%14%3
90
16th to endDay
15%6%34%28%15%
264
May1st to 15thDay
11%8%35%32%11%
468
16th to endDay
14%427%33%17%2
517
June1st to 15thDay
5%10%40%35%8%
495
16th to endDay
8%19%30%37%12%
495
July1st to 15thDay
41432%41%16%
475
16th to endDay
41223%47%20%
515
August1st to 15thDay
5%217%53%20%
493
16th to endDay
11%1422%32%27%
271
September1st to 15thDay
5%1415%42%30%
135
16th to endDay
2216%41%36%
108
October1st to 15thDay
1433%47%13%
90
16th to endDay
19%110%22%36%9%
96
November1st to 15thDay
15%224%33%16%7%
90
16th to endDay
24%10%27%22%8%6%
90
December1st to 15thDay
26%5%21%25%11%10%
90
16th to endDay
25%14%31%22%5%1
96
January1st to 15thNight
20%9%28%32%9%
900
16th to endNight
20%10%30%32%6%
960
February1st to 15thNight
18%12%30%33%5%
716
16th to endNight
17%10%43%23%5%
584
March1st to 15thNight
19%9%38%28%4
540
16th to endNight
11%9%40%32%6%
576
April1st to 15thNight
9%10%44%32%3
539
16th to endNight
13%8%39%27%9%
540
May1st to 15thNight
8%8%44%31%7%
540
16th to endNight
4331%43%16%1
563
June1st to 15thNight
314%52%26%1
540
16th to endNight
311%48%32%3
540
July1st to 15thNight
47%47%36%3
510
16th to endNight
4346%40%4
564
August1st to 15thNight
1248%42%5%
539
16th to endNight
6%437%45%5%
573
September1st to 15thNight
6%5%32%48%5%
540
16th to endNight
9%10%26%46%6%
513
October1st to 15thNight
7%113%42%29%4
561
16th to endNight
9%423%33%25%3
704
November1st to 15thNight
11%5%25%34%21%1
700
16th to endNight
14%7%26%32%17%1
837
December1st to 15thNight
19%8%27%32%11%
900
16th to endNight
21%8%28%30%10%
960
Page generated at 2017-09-23 05:43:36. Version ac04

Copyright 2017 A. Danko


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