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 2017-12-02.

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
56%
16003
26%
47796
21%
15958
61%
15958
35%
27785

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%
539
22%
1863
18%
539
54%
539
29%
1073
April16th to endNight
47%
540
24%
1800
20%
540
58%
540
31%
1055
May1st to 15thNight
52%
539
21%
1626
19%
539
58%
539
29%
1035
May16th to endNight
66%
563
21%
1685
23%
561
69%
561
32%
1017
June1st to 15thNight
78%
540
24%
1620
24%
540
80%
540
46%
843
June16th to endNight
82%
540
26%
1620
27%
540
83%
540
48%
824
July1st to 15thNight
78%
510
18%
1530
20%
510
78%
510
38%
865
July16th to endNight
86%
564
27%
1594
32%
531
86%
531
46%
837
August1st to 15thNight
83%
539
25%
1610
30%
536
83%
536
41%
881
August16th to endNight
78%
573
26%
1872
32%
573
78%
573
34%
1065
September1st to 15thNight
73%
540
28%
1857
32%
540
74%
540
36%
993
September16th to endNight
71%
537
33%
1980
36%
537
73%
537
35%
1014
October1st to 15thNight
63%
716
29%
2156
23%
716
66%
716
38%
1221
October16th to endNight
59%
768
36%
2304
27%
768
65%
768
45%
1199
November1st to 15thNight
55%
760
30%
2280
21%
760
61%
760
38%
1282
November16th to endNight
45%
927
31%
2487
18%
927
54%
927
37%
1514
December1st to 15thNight
45%
910
24%
2366
14%
910
52%
910
34%
1530
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
12%42442445%6%46%
48650
Night
11%413323346%52%
47991
TransparencyDay
36%6%10%23%18%4
48350
Night
31%5%9%24%22%6%
47796
SeeingDay
11%315%26%31%11%
5965
Night
13%321%37%21%1
16007

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%46%
2085
16th to endDay
17%6%36%5%24335%40%
2160
May1st to 15thDay
17%6%36%424446%38%
2322
16th to endDay
12%435%6%35%6%6%8%39%
2430
June1st to 15thDay
8%415%5%35%5%6%9%44%
2340
16th to endDay
6%2245%35%5%6%9%48%
2340
July1st to 15thDay
9%425%5%36%5%7%9%39%
2340
16th to endDay
5%214436%6%7%10%46%
2466
August1st to 15thDay
5%3145%35%7%8%9%44%
2340
16th to endDay
7%325%6%35%6%5%8%44%
2330
September1st to 15thDay
13%414423446%49%
2100
16th to endDay
7%213425%5%5%7%54%
1971
October1st to 15thDay
12%424423445%52%
1800
16th to endDay
12%312222335%60%
1920
November1st to 15thDay
12%323322246%55%
1908
16th to endDay
15%423312225%54%
1800
December1st to 15thDay
18%5%15%41235%5%47%
1631
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
12%41342435%7%49%
1863
16th to endNight
12%434423346%49%
1800
May1st to 15thNight
12%5%35%42445%5%47%
1625
16th to endNight
9%3243345%7%10%45%
1683
June1st to 15thNight
423423449%59%
1620
16th to endNight
42332346%9%59%
1620
July1st to 15thNight
43145%25%48%11%46%
1620
16th to endNight
311332447%11%57%
1702
August1st to 15thNight
3112425%5%7%10%53%
1620
16th to endNight
5%314435%6%6%8%49%
1872
September1st to 15thNight
10%41431335%7%54%
1857
16th to endNight
7%3135%235%5%5%56%
1980
October1st to 15thNight
11%323423346%55%
2156
16th to endNight
11%21231223463%
2304
November1st to 15thNight
9%324423336%57%
2280
16th to endNight
16%423322335%53%
2487
December1st to 15thNight
17%5%13223335%49%
2366
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
2085
16th to endDay
45%5%6%19%18%3
2160
May1st to 15thDay
46%6%7%18%17%2
2322
16th to endDay
39%8%13%22%15%
2434
June1st to 15thDay
34%7%13%25%18%
2340
16th to endDay
29%8%14%24%19%2
2340
July1st to 15thDay
36%9%13%28%11%1
2201
16th to endDay
28%9%16%28%15%1
2311
August1st to 15thDay
32%9%13%23%18%3
2326
16th to endDay
35%8%14%22%16%3
2330
September1st to 15thDay
35%6%10%22%16%9%
2100
16th to endDay
28%5%12%23%23%6%
1971
October1st to 15thDay
34%410%20%21%8%
1800
16th to endDay
28%47%22%28%9%
1920
November1st to 15thDay
30%39%27%20%7%
1908
16th to endDay
33%36%22%27%5%
1800
December1st to 15thDay
38%410%23%19%3
1631
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
34%5%10%19%21%8%
1863
16th to endNight
34%5%8%23%23%4
1800
May1st to 15thNight
37%7%10%19%19%5%
1626
16th to endNight
31%9%16%26%15%1
1685
June1st to 15thNight
21%5%13%32%23%3
1620
16th to endNight
20%5%13%29%26%5%
1620
July1st to 15thNight
26%7%15%26%21%1
1530
16th to endNight
20%8%14%33%20%3
1594
August1st to 15thNight
23%8%15%27%20%4
1610
16th to endNight
29%7%13%24%21%4
1872
September1st to 15thNight
29%410%24%21%10%
1857
16th to endNight
27%5%8%24%26%7%
1980
October1st to 15thNight
29%5%10%19%22%12%
2156
16th to endNight
24%36%21%30%13%
2304
November1st to 15thNight
29%47%25%23%9%
2280
16th to endNight
34%36%20%27%7%
2487
December1st to 15thNight
37%49%21%20%5%
2366
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
16%8%30%29%13%1
204
16th to endDay
23%6%23%28%14%3
270
May1st to 15thDay
16%6%22%33%16%3
459
16th to endDay
12%5%21%36%20%4
517
June1st to 15thDay
8%110%29%37%12%
495
16th to endDay
6%9%31%37%13%
495
July1st to 15thDay
7%17%26%42%14%
475
16th to endDay
3315%46%31%
515
August1st to 15thDay
7%5%23%45%17%
493
16th to endDay
10%5%22%45%15%
370
September1st to 15thDay
9%5%15%48%21%
255
16th to endDay
5%227%40%22%
135
October1st to 15thDay
8%216%32%32%6%
135
16th to endDay
10%10%15%34%22%6%
144
November1st to 15thDay
21%19%25%29%2
135
16th to endDay
21%10%19%27%20%1
135
December1st to 15thDay
13%336%22%19%5%
94
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%39%9%
539
16th to endNight
13%429%39%12%
540
May1st to 15thNight
14%323%42%15%
540
16th to endNight
9%214%46%25%1
563
June1st to 15thNight
5%17%42%42%2
540
16th to endNight
46%38%44%5%
540
July1st to 15thNight
6%6%35%46%5%
510
16th to endNight
3222%61%10%
564
August1st to 15thNight
3429%53%8%
539
16th to endNight
6%433%48%6%
573
September1st to 15thNight
12%5%31%46%2
540
16th to endNight
9%9%38%37%4
537
October1st to 15thNight
12%116%38%28%3
716
16th to endNight
13%321%39%21%1
768
November1st to 15thNight
10%5%24%40%17%1
760
16th to endNight
18%5%26%34%14%
927
December1st to 15thNight
19%6%26%40%7%
910
16th to endNight
18%6%28%38%7%
960
Page generated at 2017-12-03 10:16:36. Version ac04

Copyright 2017 A. Danko


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