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 2018-10-08.

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
32%
16695
6%
50754
4%
16669
35%
16669
13%
38936

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%
1015
5%
3299
2%
1015
24%
1015
7%
2751
January16th to endNight
25%
1072
7%
3292
5%
1072
27%
1072
9%
2677
February1st to 15thNight
31%
894
8%
2802
5%
892
35%
892
12%
2125
February16th to endNight
26%
684
10%
2262
7%
684
32%
684
11%
1704
March1st to 15thNight
38%
780
16%
2349
11%
780
43%
780
19%
1620
March16th to endNight
38%
825
13%
2262
6%
825
42%
825
22%
1536
April1st to 15thNight
36%
584
14%
1754
9%
584
42%
584
23%
1128
April16th to endNight
38%
489
7%
1514
3%
489
42%
489
23%
951
May1st to 15thNight
38%
389
0%
1333
0%
389
38%
389
19%
877
May16th to endNight
46%
406
0%
1055
0%
406
46%
406
29%
677
June1st to 15thNight
36%
390
0%
975
0%
390
36%
390
20%
714
June16th to endNight
51%
390
0%
975
0%
390
51%
390
25%
663
July1st to 15thNight
53%
370
0%
925
0%
370
53%
370
25%
644
July16th to endNight
59%
408
0%
1063
0%
386
62%
386
28%
689
August1st to 15thNight
55%
384
0%
1337
0%
382
56%
382
22%
835
August16th to endNight
43%
548
5%
1729
4%
548
44%
548
16%
1250
September1st to 15thNight
40%
594
8%
1829
6%
594
42%
594
19%
1279
September16th to endNight
35%
776
10%
2148
5%
776
39%
776
17%
1601
October1st to 15thNight
35%
752
10%
2322
6%
752
39%
752
14%
1725
October16th to endNight
21%
900
4%
2628
2%
900
22%
900
6%
2285
November1st to 15thNight
22%
950
5%
2878
2%
950
25%
950
8%
2411
November16th to endNight
23%
987
2%
3172
1%
987
24%
987
4%
2843
December1st to 15thNight
19%
1020
3%
3315
3%
1020
20%
1020
4%
2966
December16th to endNight
28%
1088
5%
3536
4%
1088
30%
1088
7%
2985

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%30%
52459
Night
9%11%5%9%8%46%6%5%6%24%
50869
TransparencyDay
51%7%14%19%5%
52073
Night
57%7%14%15%4
50760
SeeingDay
14%14%23%28%15%4
8544
Night
13%17%23%27%14%2
16706

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%14%6%11%7%47%11%5%6%12%
970
16th to endDay
6%15%7%11%9%6%9%7%6%5%13%
1284
February1st to 15thDay
48%6%11%11%6%10%8%6%8%18%
1397
16th to endDay
5%12%6%12%11%6%6%5%6%6%20%
1498
March1st to 15thDay
6%11%5%8%7%45%6%5%6%31%
1940
16th to endDay
7%9%47%8%47%6%5%6%31%
2312
April1st to 15thDay
8%8%47%5%345%5%6%39%
2524
16th to endDay
7%7%37%5%25%5%5%7%41%
2719
May1st to 15thDay
7%7%37%5%35%5%5%8%39%
2948
16th to endDay
11%5%35%6%25%446%43%
3409
June1st to 15thDay
13%7%37%6%45%5%5%7%31%
3315
16th to endDay
9%5%25%6%46%6%6%8%37%
3315
July1st to 15thDay
10%6%47%7%47%6%7%8%30%
3315
16th to endDay
9%5%26%7%47%7%6%8%32%
3389
August1st to 15thDay
11%5%27%5%35%45%7%40%
2868
16th to endDay
20%7%35%6%45%5%6%6%27%
2823
September1st to 15thDay
16%8%36%5%3445%8%32%
2460
16th to endDay
19%12%47%6%2445%6%26%
2142
October1st to 15thDay
15%14%5%7%5%3446%7%24%
1807
16th to endDay
16%22%8%9%6%35%336%14%
1584
November1st to 15thDay
15%17%7%12%8%45%34417%
1307
16th to endDay
10%17%7%15%12%5%6%44411%
1118
December1st to 15thDay
9%17%7%14%11%5%7%7%5%5%8%
975
16th to endDay
8%12%7%11%11%6%7%7%6%6%12%
1040
January1st to 15thNight
8%14%6%13%10%5%7%8%6%5%12%
3299
16th to endNight
10%15%6%10%8%5%7%7%5%5%16%
3292
February1st to 15thNight
48%410%9%7%10%10%5%7%22%
2796
16th to endNight
412%7%11%10%5%7%46%6%23%
2262
March1st to 15thNight
410%5%9%6%45%5%6%7%34%
2349
16th to endNight
5%8%46%6%46%5%5%7%39%
2259
April1st to 15thNight
7%11%35%4235%5%9%41%
1754
16th to endNight
6%6%26%6%36%5%7%8%40%
1514
May1st to 15thNight
7%6%38%6%46%5%6%7%37%
1332
16th to endNight
10%5%245%2435%7%46%
1055
June1st to 15thNight
11%5%48%6%35%6%5%9%33%
975
16th to endNight
6%5%25%5%5%6%7%9%7%39%
975
July1st to 15thNight
11%4246%45%7%6%10%34%
975
16th to endNight
6%423447%7%9%11%36%
1131
August1st to 15thNight
8%5%26%6%35%6%5%8%41%
1344
16th to endNight
14%6%26%6%45%5%7%7%31%
1729
September1st to 15thNight
16%7%25%5%35%46%8%34%
1829
16th to endNight
17%10%35%5%35%46%8%30%
2148
October1st to 15thNight
13%12%47%6%3445%6%29%
2322
16th to endNight
16%22%7%9%6%34445%14%
2628
November1st to 15thNight
14%14%7%13%9%44445%17%
2878
16th to endNight
10%14%8%14%12%7%6%6%448%
3172
December1st to 15thNight
9%15%9%14%10%5%8%7%5%47%
3315
16th to endNight
7%13%7%13%10%5%8%8%5%5%12%
3536

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
66%9%11%9%2
970
16th to endDay
68%411%11%2
1284
February1st to 15thDay
60%7%12%15%4
1397
16th to endDay
63%5%11%16%3
1498
March1st to 15thDay
52%6%13%22%4
1940
16th to endDay
50%7%13%21%6%
2313
April1st to 15thDay
44%6%13%25%10%
2524
16th to endDay
41%5%12%31%7%
2719
May1st to 15thDay
42%6%13%23%13%
2948
16th to endDay
40%5%10%23%18%
3414
June1st to 15thDay
49%7%12%21%8%
3315
16th to endDay
42%9%16%23%8%
3315
July1st to 15thDay
48%9%16%20%4
3136
16th to endDay
45%11%19%21%2
3194
August1st to 15thDay
41%9%20%22%5%
2850
16th to endDay
53%10%19%15%1
2823
September1st to 15thDay
50%9%22%15%1
2460
16th to endDay
56%7%17%14%2
2142
October1st to 15thDay
58%8%18%14%
1807
16th to endDay
71%8%11%7%
1584
November1st to 15thDay
69%7%9%9%2
1307
16th to endDay
75%6%9%6%1
1118
December1st to 15thDay
75%7%9%7%
975
16th to endDay
67%7%11%11%1
1040
January1st to 15thNight
68%6%10%11%1
3299
16th to endNight
66%6%10%11%4
3292
February1st to 15thNight
57%6%16%15%3
2808
16th to endNight
59%5%14%14%4
2262
March1st to 15thNight
47%6%15%23%5%
2349
16th to endNight
43%6%15%24%9%
2262
April1st to 15thNight
40%6%13%25%13%
1754
16th to endNight
38%6%13%30%10%
1514
May1st to 15thNight
42%8%11%22%14%
1333
16th to endNight
37%410%24%22%1
1055
June1st to 15thNight
45%8%13%23%7%
975
16th to endNight
37%9%17%24%10%
975
July1st to 15thNight
39%11%18%24%5%
925
16th to endNight
32%12%26%26%2
1063
August1st to 15thNight
38%9%19%25%6%1
1337
16th to endNight
48%10%18%19%2
1729
September1st to 15thNight
45%9%24%16%4
1829
16th to endNight
50%8%20%14%4
2148
October1st to 15thNight
53%8%18%17%1
2322
16th to endNight
72%8%11%7%
2628
November1st to 15thNight
69%6%11%10%1
2878
16th to endNight
77%7%8%6%
3172
December1st to 15thNight
76%8%8%6%
3315
16th to endNight
68%8%11%9%1
3536

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
10%11%30%37%10%1
90
16th to endDay
22%428%22%14%7%
96
February1st to 15thDay
11%8%34%32%8%4
90
16th to endDay
7%429%40%11%6%
110
March1st to 15thDay
10%16%30%23%12%5%
262
16th to endDay
10%15%35%28%7%3
352
April1st to 15thDay
13%16%31%22%11%5%
329
16th to endDay
11%20%24%29%11%2
451
May1st to 15thDay
11%20%23%27%14%2
543
16th to endDay
10%17%21%31%16%3
761
June1st to 15thDay
16%18%24%26%10%2
765
16th to endDay
10%15%18%30%19%5%
765
July1st to 15thDay
13%14%17%32%16%6%
735
16th to endDay
11%14%17%27%22%6%
770
August1st to 15thDay
11%9%15%29%23%10%
549
16th to endDay
21%10%25%27%12%2
456
September1st to 15thDay
23%13%25%21%12%3
375
16th to endDay
21%12%27%22%13%1
372
October1st to 15thDay
28%321%29%10%5%
157
16th to endDay
40%229%15%9%
144
November1st to 15thDay
14%7%36%22%17%1
96
16th to endDay
21%5%23%31%18%
90
December1st to 15thDay
22%6%26%27%12%4
90
16th to endDay
132%31%20%14%
96
January1st to 15thNight
12%21%27%26%9%2
1020
16th to endNight
15%19%27%24%9%2
1072
February1st to 15thNight
6%20%27%28%11%4
898
16th to endNight
7%19%31%28%11%
684
March1st to 15thNight
7%20%23%29%16%3
780
16th to endNight
7%20%24%29%16%2
825
April1st to 15thNight
11%20%24%27%13%2
584
16th to endNight
8%22%23%30%14%1
489
May1st to 15thNight
8%21%23%31%13%1
390
16th to endNight
11%17%19%35%14%1
407
June1st to 15thNight
12%20%22%28%13%2
390
16th to endNight
8%16%16%31%26%1
390
July1st to 15thNight
10%12%16%30%25%4
370
16th to endNight
7%15%10%33%26%6%
408
August1st to 15thNight
10%10%13%34%24%5%
384
16th to endNight
17%10%21%30%18%3
548
September1st to 15thNight
18%11%21%28%17%3
594
16th to endNight
19%13%24%26%13%1
776
October1st to 15thNight
20%13%20%27%13%3
752
16th to endNight
26%14%21%24%12%1
900
November1st to 15thNight
16%19%25%25%11%2
950
16th to endNight
16%20%22%24%13%2
987
December1st to 15thNight
15%20%27%26%7%2
1020
16th to endNight
10%18%25%23%16%5%
1088
Page generated at 2018-10-09 08:39:16. Version ac04

Copyright 2018 A. Danko


Fort Smith Clear Sky Chart |Charts Home