Fort Smith
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Smith clear sky chart from 2005-11-05 to 2017-04-09.

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
55%
15221
26%
45394
20%
15176
60%
15176
35%
26526

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
42%
898
29%
2327
14%
895
51%
895
37%
1416
January16th to endNight
41%
960
32%
2496
14%
960
51%
960
40%
1488
February1st to 15thNight
39%
879
22%
2288
9%
875
46%
875
33%
1447
February16th to endNight
37%
585
28%
1847
14%
585
48%
585
34%
1041
March1st to 15thNight
43%
540
23%
1980
19%
540
50%
540
25%
1196
March16th to endNight
44%
576
20%
2112
20%
576
49%
576
24%
1292
April1st to 15thNight
44%
521
23%
1803
18%
521
54%
521
28%
1046
April16th to endNight
47%
495
23%
1650
20%
495
58%
495
31%
959
May1st to 15thNight
51%
494
22%
1491
20%
494
57%
494
28%
964
May16th to endNight
66%
515
20%
1541
22%
513
68%
513
31%
942
June1st to 15thNight
77%
495
26%
1485
25%
495
79%
495
46%
777
June16th to endNight
82%
495
25%
1485
25%
495
83%
495
49%
756
July1st to 15thNight
78%
465
19%
1395
21%
465
78%
465
38%
794
July16th to endNight
85%
522
26%
1468
30%
489
85%
489
44%
783
August1st to 15thNight
83%
494
27%
1475
32%
491
84%
491
43%
794
August16th to endNight
77%
525
25%
1715
31%
525
77%
525
35%
970
September1st to 15thNight
71%
495
29%
1702
33%
495
72%
495
34%
934
September16th to endNight
70%
492
31%
1815
34%
492
72%
492
34%
934
October1st to 15thNight
63%
656
30%
1976
25%
656
66%
656
37%
1120
October16th to endNight
59%
704
34%
2112
25%
704
64%
704
43%
1122
November1st to 15thNight
55%
700
31%
2100
23%
700
63%
700
39%
1163
November16th to endNight
43%
855
29%
2295
17%
855
51%
855
35%
1421
December1st to 15thNight
46%
900
25%
2340
14%
900
52%
900
34%
1510
December16th to endNight
40%
960
26%
2496
13%
960
47%
960
29%
1657

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
13%42442445%6%46%
45886
Night
11%423323346%52%
45589
TransparencyDay
36%5%10%23%18%4
45586
Night
32%5%9%24%22%6%
45394
SeeingDay
11%315%26%31%11%
5002
Night
13%321%37%21%1
15225

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%2431333351%
1611
16th to endDay
14%433423235%52%
1728
February1st to 15thDay
17%7%3441332447%
1575
16th to endDay
16%5%35%414345%44%
1635
March1st to 15thDay
18%423323445%45%
1980
16th to endDay
19%6%36%423336%39%
2110
April1st to 15thDay
15%424424345%47%
2008
16th to endDay
17%6%35%424335%42%
1980
May1st to 15thDay
18%7%36%425%446%36%
2128
16th to endDay
13%435%6%35%6%6%7%37%
2222
June1st to 15thDay
8%425%5%35%5%6%9%43%
2145
16th to endDay
6%2245%36%5%6%8%48%
2145
July1st to 15thDay
9%425%5%37%5%8%9%38%
2145
16th to endDay
5%2145%36%6%8%10%45%
2284
August1st to 15thDay
42145%35%7%7%9%46%
2145
16th to endDay
8%425%6%35%6%5%8%44%
2135
September1st to 15thDay
13%424424446%46%
1925
16th to endDay
8%31332445%7%55%
1807
October1st to 15thDay
12%42442334452%
1650
16th to endDay
12%313222335%59%
1760
November1st to 15thDay
10%323312246%57%
1758
16th to endDay
16%424312325%52%
1662
December1st to 15thDay
18%5%15%41235%5%47%
1620
16th to endDay
19%5%24312335%46%
1728
January1st to 15thNight
15%5%2321233456%
2327
16th to endNight
12%6%1331223457%
2496
February1st to 15thNight
14%6%25%312345%49%
2278
16th to endNight
13%424322447%52%
1847
March1st to 15thNight
18%425%323335%45%
1980
16th to endNight
18%5%2343434445%
2112
April1st to 15thNight
13%413424346%50%
1803
16th to endNight
12%434424346%50%
1650
May1st to 15thNight
12%6%25%42445%5%45%
1490
16th to endNight
9%325%4345%7%10%44%
1539
June1st to 15thNight
423422449%59%
1485
16th to endNight
42332336%9%59%
1485
July1st to 15thNight
43145%36%48%11%46%
1485
16th to endNight
31332446%11%56%
1576
August1st to 15thNight
3112425%5%7%10%54%
1485
16th to endNight
5%314435%6%5%9%50%
1715
September1st to 15thNight
11%41431335%7%52%
1702
16th to endNight
7%3144235%5%5%55%
1815
October1st to 15thNight
11%323423346%55%
1976
16th to endNight
12%21231223462%
2112
November1st to 15thNight
8%324423336%57%
2100
16th to endNight
17%42332333452%
2295
December1st to 15thNight
17%5%13223335%50%
2340
16th to endNight
17%6%2442333446%
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
37%36%25%21%4
1612
16th to endDay
35%36%30%21%3
1728
February1st to 15thDay
41%310%23%17%3
1576
16th to endDay
42%38%23%18%4
1635
March1st to 15thDay
41%49%22%16%6%
1980
16th to endDay
47%48%23%14%2
2112
April1st to 15thDay
38%410%21%19%4
2008
16th to endDay
44%5%6%20%19%2
1980
May1st to 15thDay
48%6%8%19%14%2
2128
16th to endDay
41%8%13%21%13%
2226
June1st to 15thDay
34%8%13%24%17%
2145
16th to endDay
29%8%14%25%18%2
2145
July1st to 15thDay
36%9%13%27%11%1
2006
16th to endDay
29%10%16%27%15%2
2129
August1st to 15thDay
29%8%13%25%19%3
2131
16th to endDay
35%8%14%21%16%3
2135
September1st to 15thDay
37%6%10%19%16%9%
1925
16th to endDay
28%5%11%24%24%6%
1807
October1st to 15thDay
34%49%20%21%8%
1650
16th to endDay
28%37%23%28%8%
1760
November1st to 15thDay
28%39%28%21%8%
1758
16th to endDay
34%46%23%25%6%
1662
December1st to 15thDay
38%410%24%19%3
1620
16th to endDay
41%46%25%17%4
1728
January1st to 15thNight
33%37%23%27%4
2327
16th to endNight
31%37%27%25%5%
2496
February1st to 15thNight
37%37%28%18%5%
2288
16th to endNight
32%310%28%19%6%
1847
March1st to 15thNight
40%49%18%20%7%
1980
16th to endNight
41%49%23%17%3
2112
April1st to 15thNight
35%5%9%18%21%9%
1803
16th to endNight
34%5%8%23%24%4
1650
May1st to 15thNight
38%7%10%20%17%5%
1491
16th to endNight
32%9%16%26%13%1
1541
June1st to 15thNight
22%5%12%34%21%3
1485
16th to endNight
21%413%29%25%5%
1485
July1st to 15thNight
27%8%15%26%21%1
1395
16th to endNight
20%8%14%33%19%3
1468
August1st to 15thNight
22%7%14%28%21%5%
1475
16th to endNight
28%7%13%23%21%4
1715
September1st to 15thNight
31%410%23%19%10%
1702
16th to endNight
27%6%8%23%26%8%
1815
October1st to 15thNight
29%5%10%19%23%12%
1976
16th to endNight
26%35%22%28%13%
2112
November1st to 15thNight
28%47%24%24%10%
2100
16th to endNight
35%36%20%26%7%
2295
December1st to 15thNight
37%49%21%20%5%
2340
16th to endNight
42%37%22%19%5%
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
22%8%27%25%13%2
90
16th to endDay
8%13%45%18%11%2
96
February1st to 15thDay
11%14%42%22%10%
90
16th to endDay
19%16%32%19%12%
81
March1st to 15thDay
25%13%31%21%8%
90
16th to endDay
14%12%36%20%15%
96
April1st to 15thDay
17%8%30%27%12%2
179
16th to endDay
23%323%30%14%4
210
May1st to 15thDay
18%6%23%34%14%2
385
16th to endDay
13%418%35%21%5%
437
June1st to 15thDay
7%112%29%35%13%
420
16th to endDay
6%9%28%38%15%
420
July1st to 15thDay
7%18%29%42%11%
400
16th to endDay
3415%47%28%
445
August1st to 15thDay
5%323%47%19%
418
16th to endDay
11%5%19%46%16%
303
September1st to 15thDay
11%5%13%50%19%
200
16th to endDay
5%1320%36%33%
90
October1st to 15thDay
5%315%36%32%6%
90
16th to endDay
14%6%10%41%19%7%
96
November1st to 15thDay
12%116%31%35%3
90
16th to endDay
28%12%24%15%18%
90
December1st to 15thDay
14%336%22%17%5%
90
16th to endDay
21%10%30%29%8%
96
January1st to 15thNight
17%5%31%37%7%
900
16th to endNight
14%435%39%6%
960
February1st to 15thNight
17%6%31%38%5%
880
16th to endNight
15%6%37%36%4
585
March1st to 15thNight
19%5%27%41%6%
540
16th to endNight
18%5%25%38%10%
576
April1st to 15thNight
13%5%32%38%9%
521
16th to endNight
13%429%39%12%
495
May1st to 15thNight
14%225%42%14%
495
16th to endNight
9%213%45%26%1
515
June1st to 15thNight
5%17%43%40%2
495
16th to endNight
45%38%44%5%
495
July1st to 15thNight
5%6%36%46%4
465
16th to endNight
3223%61%9%
522
August1st to 15thNight
3428%53%8%
494
16th to endNight
6%432%48%6%
525
September1st to 15thNight
13%6%31%46%1
495
16th to endNight
10%10%37%36%5%
492
October1st to 15thNight
12%216%37%28%3
656
16th to endNight
13%320%39%21%1
704
November1st to 15thNight
9%5%24%40%18%1
700
16th to endNight
19%5%27%32%14%
855
December1st to 15thNight
19%6%25%40%7%
900
16th to endNight
18%6%28%38%7%
960
Page generated at 2017-04-10 08:00:35. Version ac04

Copyright 2017 A. Danko


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