Lake Bob Sandlin State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Bob Sandlin State Park 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
53%
15596
28%
46944
20%
15549
60%
15549
36%
26414

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%
900
28%
2327
12%
895
47%
895
34%
1436
January16th to endNight
33%
960
30%
2496
11%
960
44%
960
35%
1543
February1st to 15thNight
34%
856
25%
2264
10%
852
43%
852
34%
1393
February16th to endNight
29%
544
30%
1806
12%
544
45%
544
29%
1021
March1st to 15thNight
39%
540
27%
1980
17%
540
52%
540
26%
1149
March16th to endNight
43%
576
23%
2112
19%
576
52%
576
27%
1205
April1st to 15thNight
38%
539
26%
1903
17%
539
53%
539
35%
990
April16th to endNight
44%
540
26%
1800
20%
540
56%
540
32%
994
May1st to 15thNight
45%
540
23%
1641
17%
540
55%
540
31%
974
May16th to endNight
60%
563
25%
1683
25%
561
64%
561
37%
955
June1st to 15thNight
77%
540
25%
1620
26%
540
81%
540
49%
817
June16th to endNight
78%
540
26%
1620
29%
540
80%
540
45%
866
July1st to 15thNight
81%
510
21%
1530
25%
510
82%
510
43%
836
July16th to endNight
87%
564
28%
1594
34%
531
89%
531
52%
785
August1st to 15thNight
88%
539
32%
1610
36%
536
88%
536
56%
749
August16th to endNight
76%
573
24%
1875
30%
573
76%
573
32%
1090
September1st to 15thNight
72%
540
24%
1929
28%
540
74%
540
35%
1009
September16th to endNight
74%
513
35%
1891
38%
513
77%
513
41%
904
October1st to 15thNight
64%
627
33%
1947
26%
627
69%
627
42%
1021
October16th to endNight
58%
704
38%
2112
24%
704
68%
704
47%
1059
November1st to 15thNight
55%
700
31%
2100
21%
700
63%
700
41%
1127
November16th to endNight
43%
828
32%
2268
18%
828
52%
828
34%
1356
December1st to 15thNight
39%
900
26%
2340
14%
900
47%
900
30%
1512
December16th to endNight
39%
960
25%
2496
12%
960
47%
960
31%
1623

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%2442445%7%46%
47932
Night
10%423323347%53%
47141
TransparencyDay
37%410%22%20%5%
47632
Night
30%310%23%22%9%
46946
SeeingDay
11%315%26%30%13%
5617
Night
13%5%22%33%22%2
15596

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
15%5%2332233453%
1611
16th to endDay
18%6%1322233450%
1728
February1st to 15thDay
18%6%25%33323446%
1610
16th to endDay
16%7%3431223448%
1667
March1st to 15thDay
19%6%23323335%45%
1980
16th to endDay
14%7%46%424345%42%
2110
April1st to 15thDay
10%5%25%42345%7%46%
2043
16th to endDay
12%4245%35%46%7%43%
2160
May1st to 15thDay
13%6%36%5%34446%41%
2307
16th to endDay
9%425%5%46%5%6%8%40%
2430
June1st to 15thDay
5%325%4345%7%10%47%
2340
16th to endDay
6%3245%36%7%6%9%44%
2340
July1st to 15thDay
6%5%26%6%46%6%7%10%37%
2340
16th to endDay
5%3245%36%6%8%11%42%
2466
August1st to 15thDay
4213435%5%7%10%51%
2340
16th to endDay
7%5%25%6%47%7%7%11%32%
2325
September1st to 15thDay
11%426%5%3435%6%45%
2028
16th to endDay
7%32342345%6%55%
1881
October1st to 15thDay
12%323423447%52%
1671
16th to endDay
10%31331212463%
1760
November1st to 15thDay
10%424323447%51%
1758
16th to endDay
15%41331232454%
1689
December1st to 15thDay
17%8%25%32323446%
1620
16th to endDay
17%7%24413335%46%
1728
January1st to 15thNight
14%424323335%53%
2327
16th to endNight
16%5%2422224453%
2496
February1st to 15thNight
12%5%2342233453%
2254
16th to endNight
15%413313336%52%
1806
March1st to 15thNight
17%5%24313336%47%
1980
16th to endNight
9%5%3443335%7%48%
2112
April1st to 15thNight
7%3234235%5%7%53%
1903
16th to endNight
11%4144235%46%52%
1800
May1st to 15thNight
10%4145%25%45%6%50%
1640
16th to endNight
5%5%2442446%11%48%
1683
June1st to 15thNight
231332345%8%62%
1620
16th to endNight
431232447%9%55%
1620
July1st to 15thNight
331442446%12%50%
1620
16th to endNight
1123245%7%14%56%
1702
August1st to 15thNight
22121246%10%63%
1620
16th to endNight
5%4245%36%7%7%9%43%
1875
September1st to 15thNight
9%41332335%8%53%
1929
16th to endNight
6%313313347%59%
1891
October1st to 15thNight
9%323323235%60%
1947
16th to endNight
11%2112223465%
2112
November1st to 15thNight
7%324223346%58%
2100
16th to endNight
14%414323235%53%
2268
December1st to 15thNight
14%6%34423345%47%
2340
16th to endNight
15%7%24323345%46%
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
36%27%20%26%7%
1612
16th to endDay
38%25%20%26%7%
1728
February1st to 15thDay
43%2420%23%6%
1611
16th to endDay
41%25%18%23%9%
1667
March1st to 15thDay
43%27%19%20%7%
1980
16th to endDay
44%38%18%22%3
2112
April1st to 15thDay
37%49%23%17%8%
2043
16th to endDay
39%49%20%20%4
2160
May1st to 15thDay
44%49%16%19%6%
2307
16th to endDay
40%6%12%23%15%2
2434
June1st to 15thDay
30%6%13%29%18%1
2340
16th to endDay
33%6%13%23%20%3
2340
July1st to 15thDay
37%6%15%27%12%
2201
16th to endDay
30%6%21%27%12%
2311
August1st to 15thDay
26%6%14%33%17%2
2326
16th to endDay
41%8%16%22%9%2
2325
September1st to 15thDay
38%410%21%16%8%
2028
16th to endDay
28%39%23%25%9%
1881
October1st to 15thDay
33%210%17%20%15%
1671
16th to endDay
27%2321%31%13%
1760
November1st to 15thDay
33%29%22%23%8%
1758
16th to endDay
34%2416%31%10%
1689
December1st to 15thDay
42%27%19%21%6%
1620
16th to endDay
42%26%22%20%5%
1728
January1st to 15thNight
35%27%16%28%10%
2327
16th to endNight
36%15%19%25%11%
2496
February1st to 15thNight
35%26%21%22%11%
2264
16th to endNight
35%28%20%22%11%
1806
March1st to 15thNight
38%27%19%20%10%
1980
16th to endNight
36%49%21%22%5%
2112
April1st to 15thNight
29%312%22%20%11%
1903
16th to endNight
32%39%21%24%7%
1800
May1st to 15thNight
34%5%11%20%17%10%
1641
16th to endNight
29%5%17%26%17%3
1685
June1st to 15thNight
19%5%12%33%24%3
1620
16th to endNight
23%5%13%27%25%4
1620
July1st to 15thNight
25%5%16%33%17%1
1530
16th to endNight
16%7%20%34%19%2
1594
August1st to 15thNight
15%417%34%23%4
1610
16th to endNight
32%6%13%27%16%3
1875
September1st to 15thNight
28%5%12%24%19%9%
1929
16th to endNight
25%28%24%27%12%
1891
October1st to 15thNight
27%29%21%21%17%
1947
16th to endNight
23%2420%29%20%
2112
November1st to 15thNight
27%28%22%26%11%
2100
16th to endNight
35%2415%28%13%
2268
December1st to 15thNight
40%28%20%20%8%
2340
16th to endNight
40%27%20%20%8%
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
14%7%33%27%16%
90
16th to endDay
18%8%41%22%8%
96
February1st to 15thDay
17%6%38%28%7%
90
16th to endDay
16%349%19%9%1
81
March1st to 15thDay
24%12%33%22%6%1
90
16th to endDay
11%9%31%27%19%1
96
April1st to 15thDay
17%8%30%26%16%1
162
16th to endDay
21%5%28%26%14%3
270
May1st to 15thDay
13%7%31%31%11%3
444
16th to endDay
14%222%34%21%4
517
June1st to 15thDay
6%26%32%39%11%
495
16th to endDay
6%19%28%38%16%
495
July1st to 15thDay
5%16%33%37%15%
475
16th to endDay
41217%47%26%
515
August1st to 15thDay
7%1222%43%22%
493
16th to endDay
13%2318%41%20%
365
September1st to 15thDay
6%214%38%38%
183
16th to endDay
4120%40%32%
108
October1st to 15thDay
110%37%36%14%
90
16th to endDay
15%28%34%32%7%
96
November1st to 15thDay
20%320%24%28%3
90
16th to endDay
25%6%26%26%10%4
90
December1st to 15thDay
27%421%28%11%6%
90
16th to endDay
25%10%29%28%6%1
96
January1st to 15thNight
17%11%29%32%9%
900
16th to endNight
18%9%36%28%6%
960
February1st to 15thNight
17%9%35%30%7%
856
16th to endNight
20%11%36%27%4
544
March1st to 15thNight
21%6%29%34%8%
540
16th to endNight
12%6%32%38%9%
576
April1st to 15thNight
9%7%41%31%11%
539
16th to endNight
13%6%32%32%12%1
540
May1st to 15thNight
11%5%30%37%13%1
540
16th to endNight
7%222%41%23%2
563
June1st to 15thNight
418%39%42%3
540
16th to endNight
5%8%33%44%7%
540
July1st to 15thNight
4340%47%3
510
16th to endNight
2425%56%11%
564
August1st to 15thNight
4226%56%9%
539
16th to endNight
9%1227%49%9%
573
September1st to 15thNight
13%5%27%46%6%
540
16th to endNight
9%18%31%44%4
513
October1st to 15thNight
9%216%39%28%3
627
16th to endNight
14%321%33%24%3
704
November1st to 15thNight
9%425%40%18%2
700
16th to endNight
18%7%26%32%14%
828
December1st to 15thNight
18%9%26%37%7%
900
16th to endNight
20%8%28%34%8%
960
Page generated at 2017-09-23 05:43:35. Version ac04

Copyright 2017 A. Danko


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