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 2017-05-01.

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
31%
14972
6%
45717
4%
14946
34%
14946
12%
35254

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
20%
925
4%
3044
1%
925
23%
925
7%
2557
January16th to endNight
24%
981
7%
3039
5%
981
27%
981
9%
2462
February1st to 15thNight
32%
824
8%
2582
5%
822
36%
822
13%
1938
February16th to endNight
26%
632
11%
2090
7%
632
32%
632
11%
1569
March1st to 15thNight
36%
720
15%
2168
11%
720
41%
720
18%
1523
March16th to endNight
37%
762
13%
2088
6%
762
41%
762
22%
1430
April1st to 15thNight
34%
539
12%
1619
8%
539
40%
539
22%
1057
April16th to endNight
40%
457
8%
1414
4%
457
44%
457
24%
874
May1st to 15thNight
39%
331
0%
1135
0%
331
39%
331
19%
747
May16th to endNight
44%
342
0%
889
0%
342
44%
342
27%
585
June1st to 15thNight
38%
330
0%
825
0%
330
38%
330
20%
597
June16th to endNight
50%
330
0%
825
0%
330
50%
330
26%
554
July1st to 15thNight
51%
310
0%
775
0%
310
51%
310
24%
545
July16th to endNight
59%
348
0%
897
0%
326
63%
326
28%
574
August1st to 15thNight
53%
330
0%
1148
0%
328
53%
328
19%
737
August16th to endNight
42%
463
4%
1462
4%
463
43%
463
16%
1073
September1st to 15thNight
40%
502
7%
1547
5%
502
42%
502
18%
1085
September16th to endNight
31%
656
8%
1818
3%
656
35%
656
15%
1392
October1st to 15thNight
35%
660
10%
2040
6%
660
39%
660
14%
1520
October16th to endNight
21%
825
3%
2409
2%
825
22%
825
7%
2088
November1st to 15thNight
22%
875
6%
2651
3%
875
25%
875
8%
2215
November16th to endNight
22%
908
2%
2928
1%
908
23%
908
4%
2627
December1st to 15thNight
18%
930
4%
3060
3%
930
19%
930
4%
2745
December16th to endNight
26%
992
5%
3264
3%
992
28%
992
6%
2760

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%9%48%7%46%5%5%7%29%
46121
Night
9%11%5%9%8%46%6%5%6%24%
45832
TransparencyDay
52%7%15%18%5%
45735
Night
57%7%14%15%4
45723
SeeingDay
14%16%22%26%15%4
6382
Night
13%19%23%27%14%2
14983

By Month

Percentage Cloud Cover NW (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
10%15%6%11%8%47%11%5%6%11%
895
16th to endDay
6%15%7%11%8%5%10%7%6%6%14%
1185
February1st to 15thDay
48%6%11%11%5%9%8%6%8%18%
1286
16th to endDay
6%13%6%12%10%6%6%46%6%21%
1384
March1st to 15thDay
6%10%5%8%7%46%7%5%6%30%
1791
16th to endDay
7%9%5%7%8%47%6%5%6%31%
2135
April1st to 15thDay
9%8%5%7%5%345%6%6%37%
2329
16th to endDay
6%7%37%5%25%5%5%7%41%
2544
May1st to 15thDay
7%7%47%5%36%45%8%38%
2497
16th to endDay
11%5%35%6%25%446%42%
2871
June1st to 15thDay
13%6%37%6%45%5%5%8%33%
2805
16th to endDay
9%5%25%7%46%6%6%9%37%
2805
July1st to 15thDay
10%7%48%7%47%6%7%8%28%
2805
16th to endDay
9%5%26%7%48%7%6%8%31%
2895
August1st to 15thDay
11%5%37%6%35%45%7%38%
2475
16th to endDay
21%7%36%6%35%5%5%6%26%
2387
September1st to 15thDay
17%8%36%5%35%5%5%8%31%
2082
16th to endDay
21%11%36%6%345%5%6%24%
1812
October1st to 15thDay
15%15%5%6%5%3446%7%24%
1590
16th to endDay
16%21%8%9%6%35%346%15%
1452
November1st to 15thDay
16%17%7%12%7%4433318%
1204
16th to endDay
9%17%7%15%13%5%6%34412%
1032
December1st to 15thDay
9%17%7%14%11%6%7%8%45%7%
900
16th to endDay
9%13%8%11%10%5%6%7%7%6%12%
960
January1st to 15thNight
8%14%6%13%10%5%8%8%6%5%11%
3044
16th to endNight
9%15%6%10%8%5%7%7%6%5%16%
3039
February1st to 15thNight
48%410%10%7%9%9%5%7%23%
2576
16th to endNight
5%12%7%11%9%5%6%46%6%24%
2090
March1st to 15thNight
410%5%9%7%46%5%5%7%32%
2168
16th to endNight
5%8%47%6%45%5%5%7%39%
2085
April1st to 15thNight
7%11%45%4235%5%9%39%
1619
16th to endNight
5%5%26%6%36%47%8%42%
1414
May1st to 15thNight
6%7%48%7%35%6%5%7%37%
1134
16th to endNight
12%5%245%25%347%45%
889
June1st to 15thNight
10%5%47%6%35%7%5%9%34%
825
16th to endNight
5%425%5%5%6%7%9%8%40%
825
July1st to 15thNight
12%435%6%45%7%6%10%34%
825
16th to endNight
6%433347%8%9%12%36%
965
August1st to 15thNight
8%5%26%6%35%6%5%7%40%
1155
16th to endNight
15%7%26%6%445%7%7%31%
1462
September1st to 15thNight
15%7%25%5%35%46%8%35%
1547
16th to endNight
19%10%45%5%35%45%7%28%
1818
October1st to 15thNight
13%12%47%6%35%5%5%6%29%
2040
16th to endNight
16%22%8%9%6%34445%15%
2409
November1st to 15thNight
15%14%7%13%8%43445%17%
2651
16th to endNight
10%14%8%14%13%7%6%6%438%
2928
December1st to 15thNight
8%15%9%14%10%5%9%8%5%47%
3060
16th to endNight
8%13%7%14%9%5%7%8%5%5%13%
3264

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
67%9%12%8%2
895
16th to endDay
67%412%12%3
1185
February1st to 15thDay
59%7%12%16%4
1286
16th to endDay
63%411%16%4
1384
March1st to 15thDay
52%6%12%21%5%
1791
16th to endDay
50%8%13%21%5%
2136
April1st to 15thDay
46%6%13%24%9%
2329
16th to endDay
40%5%12%33%7%
2544
May1st to 15thDay
43%6%13%22%13%
2497
16th to endDay
42%5%11%21%18%
2876
June1st to 15thDay
47%7%13%21%9%
2805
16th to endDay
42%9%17%23%7%
2805
July1st to 15thDay
50%9%16%18%4
2626
16th to endDay
46%12%19%20%2
2700
August1st to 15thDay
43%9%21%21%3
2457
16th to endDay
54%9%19%14%
2387
September1st to 15thDay
50%10%22%14%1
2082
16th to endDay
58%8%18%11%3
1812
October1st to 15thDay
57%7%19%14%
1590
16th to endDay
70%9%12%7%
1452
November1st to 15thDay
69%7%9%10%2
1204
16th to endDay
75%6%9%7%1
1032
December1st to 15thDay
76%7%8%7%
900
16th to endDay
66%8%12%11%1
960
January1st to 15thNight
69%7%11%10%1
3044
16th to endNight
65%6%11%11%5%
3039
February1st to 15thNight
56%5%17%16%3
2588
16th to endNight
59%5%13%15%5%
2090
March1st to 15thNight
48%6%14%23%5%1
2168
16th to endNight
43%6%16%24%8%
2088
April1st to 15thNight
41%6%14%24%12%
1619
16th to endNight
37%6%13%31%10%
1414
May1st to 15thNight
42%8%11%22%14%
1135
16th to endNight
39%410%22%22%1
889
June1st to 15thNight
43%9%15%24%6%
825
16th to endNight
35%10%19%25%9%
825
July1st to 15thNight
40%10%18%22%6%
775
16th to endNight
30%12%27%26%2
897
August1st to 15thNight
40%10%19%24%5%
1148
16th to endNight
50%10%18%18%2
1462
September1st to 15thNight
44%10%25%15%3
1547
16th to endNight
54%8%21%11%3
1818
October1st to 15thNight
54%7%17%17%2
2040
16th to endNight
71%8%11%8%
2409
November1st to 15thNight
69%6%11%11%1
2651
16th to endNight
77%7%7%6%
2928
December1st to 15thNight
76%8%7%6%
3060
16th to endNight
69%8%11%9%1
3264

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
8%8%31%36%13%1
60
16th to endDay
21%135%25%6%9%
64
February1st to 15thDay
16%5%20%38%13%6%
60
16th to endDay
10%5%28%41%9%4
74
March1st to 15thDay
10%19%29%19%13%6%
207
16th to endDay
11%18%32%25%7%3
288
April1st to 15thDay
15%19%30%20%10%4
269
16th to endDay
10%21%22%29%13%2
393
May1st to 15thDay
9%21%22%25%17%4
395
16th to endDay
10%20%18%28%17%4
575
June1st to 15thDay
14%21%20%28%11%3
585
16th to endDay
9%19%18%27%19%6%
585
July1st to 15thDay
12%17%18%30%15%5%
555
16th to endDay
11%16%16%25%22%6%
594
August1st to 15thDay
12%10%15%29%23%8%
418
16th to endDay
22%11%24%26%12%2
319
September1st to 15thDay
25%14%24%20%10%3
255
16th to endDay
25%17%26%17%11%1
252
October1st to 15thDay
32%417%28%12%4
90
16th to endDay
41%128%17%10%1
96
November1st to 15thDay
14%6%39%20%18%1
64
16th to endDay
20%5%25%30%20%
60
December1st to 15thDay
25%125%33%11%3
60
16th to endDay
139%28%14%17%
64
January1st to 15thNight
12%22%26%27%9%2
930
16th to endNight
14%21%28%24%8%2
981
February1st to 15thNight
7%21%24%29%12%4
828
16th to endNight
8%20%29%29%11%
632
March1st to 15thNight
8%21%23%27%15%3
720
16th to endNight
7%21%23%28%16%2
762
April1st to 15thNight
12%22%25%25%12%1
539
16th to endNight
6%22%23%30%14%1
457
May1st to 15thNight
7%23%21%31%15%1
332
16th to endNight
12%20%16%33%14%2
343
June1st to 15thNight
10%22%20%28%15%2
330
16th to endNight
6%18%17%29%25%1
330
July1st to 15thNight
10%15%16%28%24%3
310
16th to endNight
6%18%9%31%27%6%
348
August1st to 15thNight
11%11%13%34%23%5%
330
16th to endNight
17%11%20%28%18%3
463
September1st to 15thNight
16%12%19%30%16%3
502
16th to endNight
22%14%24%24%11%1
656
October1st to 15thNight
20%14%20%28%13%2
660
16th to endNight
25%14%21%23%12%1
825
November1st to 15thNight
16%20%24%24%11%2
875
16th to endNight
16%21%20%24%13%2
908
December1st to 15thNight
14%21%27%26%7%2
930
16th to endNight
10%19%25%22%15%5%
992
Page generated at 2017-05-02 06:43:38. Version ac04

Copyright 2017 A. Danko


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