Little Rock
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Little Rock clear sky chart from 2005-11-05 to 2017-08-12.

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
49%
15535
26%
46673
18%
15490
57%
15490
33%
27615

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
32%
899
28%
2327
10%
895
44%
895
32%
1475
January16th to endNight
30%
960
27%
2496
9%
960
41%
960
31%
1595
February1st to 15thNight
29%
850
21%
2259
7%
847
37%
847
29%
1479
February16th to endNight
27%
619
29%
1881
11%
619
41%
619
30%
1107
March1st to 15thNight
31%
540
22%
1980
15%
540
41%
540
22%
1207
March16th to endNight
37%
576
21%
2106
15%
576
47%
576
23%
1277
April1st to 15thNight
35%
539
25%
1797
15%
539
51%
539
31%
994
April16th to endNight
40%
540
25%
1800
19%
540
53%
540
32%
1012
May1st to 15thNight
49%
540
20%
1770
16%
540
57%
540
27%
1074
May16th to endNight
53%
563
22%
1685
18%
561
60%
561
31%
1037
June1st to 15thNight
77%
540
25%
1449
22%
540
80%
540
50%
797
June16th to endNight
75%
540
27%
1525
24%
540
78%
540
46%
839
July1st to 15thNight
73%
510
18%
1530
18%
510
76%
510
35%
890
July16th to endNight
84%
564
25%
1594
29%
531
84%
531
41%
883
August1st to 15thNight
79%
527
25%
1632
28%
524
81%
524
43%
862
August16th to endNight
79%
525
24%
1750
29%
525
79%
525
32%
1013
September1st to 15thNight
69%
495
27%
1650
29%
495
71%
495
33%
957
September16th to endNight
66%
552
31%
1802
29%
552
71%
552
37%
976
October1st to 15thNight
59%
660
32%
1980
24%
660
64%
660
38%
1107
October16th to endNight
54%
704
35%
2112
24%
704
63%
704
41%
1143
November1st to 15thNight
50%
700
32%
2100
22%
700
59%
700
37%
1167
November16th to endNight
42%
732
29%
2340
21%
732
53%
732
30%
1381
December1st to 15thNight
37%
900
21%
2520
11%
900
45%
900
28%
1638
December16th to endNight
34%
960
23%
2588
12%
960
42%
960
27%
1705

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
12%5%2442445%7%43%
47278
Night
11%424423347%50%
46869
TransparencyDay
38%5%11%22%18%4
46979
Night
33%49%23%21%6%
46673
SeeingDay
11%5%19%27%25%10%
5552
Night
13%6%24%32%20%2
15536

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%23412345%46%
1611
16th to endDay
16%6%34412345%46%
1728
February1st to 15thDay
17%6%24323336%46%
1601
16th to endDay
17%6%35%6%23335%41%
1602
March1st to 15thDay
19%5%35%423345%41%
1980
16th to endDay
16%6%35%5%24446%40%
2114
April1st to 15thDay
12%6%24423346%48%
2151
16th to endDay
14%6%25%5%24446%42%
2160
May1st to 15thDay
15%6%35%5%25%5%5%6%39%
2178
16th to endDay
9%426%7%46%6%7%9%35%
2430
June1st to 15thDay
5%325%5%36%5%7%9%44%
2505
16th to endDay
5%3245%46%6%7%10%43%
2429
July1st to 15thDay
5%436%7%46%7%7%10%34%
2340
16th to endDay
5%3246%37%6%7%11%41%
2466
August1st to 15thDay
6%425%5%36%7%8%10%39%
2232
16th to endDay
7%426%5%36%6%8%10%38%
2100
September1st to 15thDay
13%5%24435%5%6%7%40%
1980
16th to endDay
12%424324445%51%
1815
October1st to 15thDay
14%423323346%51%
1650
16th to endDay
15%312212235%59%
1760
November1st to 15thDay
10%5%1321335%5%57%
1758
16th to endDay
16%7%2441333448%
1616
December1st to 15thDay
18%7%3422325%5%43%
1440
16th to endDay
19%6%35%423345%41%
1632
January1st to 15thNight
17%6%2431223451%
2327
16th to endNight
16%5%1342333450%
2496
February1st to 15thNight
18%6%24322326%47%
2250
16th to endNight
15%433422335%52%
1881
March1st to 15thNight
17%6%35%314245%44%
1980
16th to endNight
14%5%25%423446%45%
2106
April1st to 15thNight
10%32342345%8%50%
1797
16th to endNight
9%424423348%50%
1800
May1st to 15thNight
13%5%2342445%7%45%
1769
16th to endNight
9%425%425%45%8%46%
1683
June1st to 15thNight
22133245%6%9%58%
1449
16th to endNight
332332446%9%57%
1525
July1st to 15thNight
33245%46%5%7%12%44%
1620
16th to endNight
32123346%7%12%51%
1702
August1st to 15thNight
4235%235%6%12%52%
1642
16th to endNight
4315%5%36%6%7%10%44%
1750
September1st to 15thNight
9%5%2432445%8%49%
1650
16th to endNight
7%31442445%7%54%
1802
October1st to 15thNight
9%315%323246%56%
1980
16th to endNight
13%21322232362%
2112
November1st to 15thNight
10%414322347%55%
2100
16th to endNight
15%6%2332332452%
2340
December1st to 15thNight
18%6%2441334446%
2520
16th to endNight
17%7%3442333445%
2588

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
40%37%24%19%5%
1612
16th to endDay
40%36%23%20%4
1728
February1st to 15thDay
39%310%23%17%4
1603
16th to endDay
45%37%20%18%4
1602
March1st to 15thDay
45%39%17%17%6%
1980
16th to endDay
44%411%23%14%1
2116
April1st to 15thDay
36%5%10%23%18%5%
2151
16th to endDay
41%48%21%19%3
2160
May1st to 15thDay
44%7%10%15%18%3
2178
16th to endDay
40%8%15%22%11%1
2434
June1st to 15thDay
33%6%13%27%18%
2505
16th to endDay
31%7%13%25%18%3
2429
July1st to 15thDay
37%9%13%24%12%1
2201
16th to endDay
31%9%17%25%14%1
2311
August1st to 15thDay
34%8%15%24%14%2
2218
16th to endDay
36%9%16%20%14%3
2100
September1st to 15thDay
38%7%12%17%16%7%
1980
16th to endDay
34%47%21%24%7%
1815
October1st to 15thDay
34%48%19%24%9%
1650
16th to endDay
28%3423%29%10%
1760
November1st to 15thDay
28%38%25%25%8%
1758
16th to endDay
40%36%18%23%6%
1616
December1st to 15thDay
43%310%22%14%5%
1440
16th to endDay
44%310%19%17%4
1632
January1st to 15thNight
38%16%21%26%4
2327
16th to endNight
37%36%23%21%6%
2496
February1st to 15thNight
40%37%23%19%5%
2259
16th to endNight
35%28%25%19%8%
1881
March1st to 15thNight
42%310%16%19%8%
1980
16th to endNight
41%48%24%19%2
2106
April1st to 15thNight
31%5%10%23%21%8%
1797
16th to endNight
32%5%11%23%23%4
1800
May1st to 15thNight
37%5%10%20%18%6%
1770
16th to endNight
34%7%14%24%16%1
1685
June1st to 15thNight
20%6%14%30%25%2
1449
16th to endNight
23%6%11%28%24%5%
1525
July1st to 15thNight
28%9%17%27%15%2
1530
16th to endNight
22%10%14%30%18%3
1594
August1st to 15thNight
23%6%17%31%18%3
1632
16th to endNight
29%8%14%24%18%3
1750
September1st to 15thNight
32%6%11%22%18%8%
1650
16th to endNight
28%5%9%20%26%10%
1802
October1st to 15thNight
30%38%20%23%12%
1980
16th to endNight
28%2419%32%12%
2112
November1st to 15thNight
30%36%22%24%12%
2100
16th to endNight
37%35%18%28%6%
2340
December1st to 15thNight
42%38%21%17%6%
2520
16th to endNight
42%38%21%19%4
2588

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
26%11%36%16%7%1
90
16th to endDay
19%27%32%13%7%
96
February1st to 15thDay
16%22%41%15%31
90
16th to endDay
14%23%39%16%32
81
March1st to 15thDay
28%17%41%8%3
90
16th to endDay
11%26%22%32%9%
100
April1st to 15thDay
15%11%36%23%11%1
270
16th to endDay
21%7%26%25%15%3
270
May1st to 15thDay
16%8%29%27%14%3
315
16th to endDay
10%6%24%29%22%6%
517
June1st to 15thDay
7%212%34%31%12%
495
16th to endDay
5%216%34%27%12%
495
July1st to 15thDay
5%215%33%30%11%
475
16th to endDay
4425%40%24%
515
August1st to 15thDay
8%7%27%37%17%
417
16th to endDay
13%1420%41%20%
268
September1st to 15thDay
10%25%24%43%14%
255
16th to endDay
9%17%25%33%13%
161
October1st to 15thDay
12%428%32%16%5%
90
16th to endDay
17%6%21%36%13%4
96
November1st to 15thDay
17%5%23%27%22%3
90
16th to endDay
28%15%26%20%6%2
90
December1st to 15thDay
23%8%33%15%14%4
90
16th to endDay
23%17%38%15%4
96
January1st to 15thNight
21%9%32%28%8%
900
16th to endNight
18%10%37%30%3
960
February1st to 15thNight
20%10%35%28%4
850
16th to endNight
17%13%39%26%3
619
March1st to 15thNight
17%10%35%30%5%
540
16th to endNight
17%9%32%31%9%
576
April1st to 15thNight
11%10%38%26%10%
539
16th to endNight
11%8%35%31%12%
540
May1st to 15thNight
13%5%26%40%13%
540
16th to endNight
11%223%33%25%3
563
June1st to 15thNight
2112%42%36%4
540
16th to endNight
4110%41%35%5%
540
July1st to 15thNight
211%34%45%5%
510
16th to endNight
4428%52%10%
564
August1st to 15thNight
45%30%48%10%
527
16th to endNight
5%433%48%7%
525
September1st to 15thNight
12%18%29%42%6%
495
16th to endNight
7%115%33%36%5%
552
October1st to 15thNight
11%219%33%29%3
660
16th to endNight
13%424%34%20%1
704
November1st to 15thNight
11%9%23%34%19%1
700
16th to endNight
18%7%27%31%14%
732
December1st to 15thNight
21%7%29%33%8%
900
16th to endNight
21%9%31%30%7%
960
Page generated at 2017-08-13 13:16:55. Version ac04

Copyright 2017 A. Danko


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