Siloam Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Siloam Springs clear sky chart from 2005-11-05 to 2017-12-04.

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
46%
16064
26%
47858
17%
16017
54%
16017
34%
27622

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
29%
900
28%
2327
10%
895
41%
895
32%
1448
January16th to endNight
31%
960
30%
2496
11%
960
43%
960
35%
1501
February1st to 15thNight
27%
880
21%
2288
7%
876
36%
876
31%
1460
February16th to endNight
24%
603
27%
1865
8%
603
40%
603
29%
1085
March1st to 15thNight
33%
540
23%
1980
15%
540
45%
540
23%
1203
March16th to endNight
33%
576
19%
2112
14%
576
41%
576
23%
1281
April1st to 15thNight
33%
539
23%
1863
15%
539
47%
539
28%
1060
April16th to endNight
33%
540
23%
1779
13%
540
49%
540
29%
1062
May1st to 15thNight
48%
539
22%
1620
20%
539
55%
539
31%
999
May16th to endNight
51%
563
20%
1685
16%
561
59%
561
33%
1018
June1st to 15thNight
68%
540
21%
1620
19%
540
71%
540
46%
836
June16th to endNight
73%
540
25%
1620
21%
540
78%
540
50%
815
July1st to 15thNight
73%
510
20%
1530
19%
510
75%
510
42%
837
July16th to endNight
81%
564
29%
1594
33%
531
83%
531
50%
795
August1st to 15thNight
79%
539
27%
1610
31%
536
80%
536
44%
846
August16th to endNight
77%
573
27%
1854
32%
573
78%
573
40%
990
September1st to 15thNight
69%
540
28%
1859
31%
540
72%
540
35%
992
September16th to endNight
66%
537
33%
1980
32%
537
72%
537
37%
975
October1st to 15thNight
53%
714
29%
2154
22%
714
59%
714
39%
1187
October16th to endNight
48%
768
34%
2304
21%
768
58%
768
42%
1215
November1st to 15thNight
40%
760
31%
2280
16%
760
53%
760
38%
1253
November16th to endNight
34%
959
30%
2519
14%
959
45%
959
36%
1532
December1st to 15thNight
31%
920
23%
2423
9%
920
41%
920
31%
1559
December16th to endNight
29%
960
25%
2496
9%
960
40%
960
27%
1673

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%45%
48584
Night
10%5%24323446%51%
48053
TransparencyDay
37%411%26%16%3
48284
Night
32%311%26%20%4
47858
SeeingDay
11%5%21%28%24%7%
6012
Night
13%7%27%32%16%1
16065

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%7%15%412236%50%
1611
16th to endDay
12%5%24423246%50%
1728
February1st to 15thDay
12%9%45%5%23335%43%
1575
16th to endDay
13%8%35%423346%44%
1615
March1st to 15thDay
15%7%34424346%42%
1980
16th to endDay
19%6%46%4245%4437%
2110
April1st to 15thDay
14%6%24435%346%43%
2085
16th to endDay
17%7%36%5%24445%38%
2178
May1st to 15thDay
17%6%26%5%24445%38%
2331
16th to endDay
12%6%25%6%3446%7%38%
2430
June1st to 15thDay
8%425%435%5%6%8%45%
2340
16th to endDay
6%214436%6%7%9%48%
2340
July1st to 15thDay
8%4246%36%6%7%10%37%
2340
16th to endDay
5%3235%35%5%7%11%46%
2466
August1st to 15thDay
6%3244346%7%10%44%
2340
16th to endDay
7%325%5%35%5%6%8%46%
2346
September1st to 15thDay
13%42443345%8%44%
2098
16th to endDay
9%313435%46%8%48%
1974
October1st to 15thDay
13%5%24323336%51%
1800
16th to endDay
10%5%14312335%58%
1920
November1st to 15thDay
11%5%23413347%52%
1908
16th to endDay
14%6%24213426%50%
1770
December1st to 15thDay
14%6%45%5%2334444%
1571
16th to endDay
15%9%34313336%43%
1728
January1st to 15thNight
13%5%24423335%52%
2327
16th to endNight
10%5%35%323235%54%
2496
February1st to 15thNight
12%8%25%323245%48%
2278
16th to endNight
10%5%24424346%49%
1865
March1st to 15thNight
12%7%25%4245%46%43%
1980
16th to endNight
16%6%35%423445%44%
2112
April1st to 15thNight
10%5%14335%445%50%
1863
16th to endNight
13%5%24424446%47%
1779
May1st to 15thNight
11%5%2443445%7%47%
1619
16th to endNight
10%4233246%6%9%44%
1683
June1st to 15thNight
5%31332345%8%59%
1620
16th to endNight
321222447%10%59%
1620
July1st to 15thNight
5%323425%5%5%11%51%
1620
16th to endNight
211342347%10%57%
1702
August1st to 15thNight
321242447%11%53%
1620
16th to endNight
4214435%6%6%8%53%
1854
September1st to 15thNight
10%41342345%6%53%
1859
16th to endNight
7%5%1432335%7%56%
1980
October1st to 15thNight
10%414323347%54%
2154
16th to endNight
10%312213235%61%
2304
November1st to 15thNight
10%5%12223335%58%
2280
16th to endNight
12%6%2331333454%
2519
December1st to 15thNight
13%7%24323346%46%
2423
16th to endNight
14%8%45%422335%43%
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%18%28%20%2
1612
16th to endDay
36%19%31%17%3
1728
February1st to 15thDay
43%310%26%13%2
1576
16th to endDay
41%29%27%15%4
1615
March1st to 15thDay
43%39%21%15%6%
1980
16th to endDay
48%410%22%12%1
2112
April1st to 15thDay
41%312%22%16%2
2085
16th to endDay
47%410%19%16%2
2178
May1st to 15thDay
48%310%21%15%1
2331
16th to endDay
43%414%24%12%
2434
June1st to 15thDay
34%5%14%28%16%
2340
16th to endDay
28%5%17%27%18%2
2340
July1st to 15thDay
36%6%16%29%10%
2201
16th to endDay
28%5%18%32%13%1
2311
August1st to 15thDay
31%5%16%26%17%2
2326
16th to endDay
33%5%14%28%14%4
2346
September1st to 15thDay
36%5%10%22%15%8%
2098
16th to endDay
31%410%27%21%4
1974
October1st to 15thDay
34%39%25%19%7%
1800
16th to endDay
30%28%28%23%7%
1920
November1st to 15thDay
32%29%28%19%7%
1908
16th to endDay
37%26%23%26%3
1770
December1st to 15thDay
43%29%25%15%2
1571
16th to endDay
43%28%25%15%3
1728
January1st to 15thNight
36%27%27%21%3
2327
16th to endNight
33%29%28%21%4
2496
February1st to 15thNight
38%210%27%17%3
2288
16th to endNight
35%29%28%19%4
1865
March1st to 15thNight
40%410%19%19%5%
1980
16th to endNight
42%310%25%15%2
2112
April1st to 15thNight
35%310%24%21%5%
1863
16th to endNight
37%310%24%19%3
1779
May1st to 15thNight
36%5%12%23%19%3
1620
16th to endNight
32%7%18%26%14%1
1685
June1st to 15thNight
22%416%31%22%2
1620
16th to endNight
19%5%16%31%21%5%
1620
July1st to 15thNight
25%5%14%33%19%1
1530
16th to endNight
19%414%38%20%2
1594
August1st to 15thNight
22%6%14%29%23%2
1610
16th to endNight
26%5%13%27%21%5%
1854
September1st to 15thNight
30%39%28%17%10%
1859
16th to endNight
27%210%28%26%4
1980
October1st to 15thNight
29%311%22%23%8%
2154
16th to endNight
26%27%26%28%9%
2304
November1st to 15thNight
28%38%26%23%8%
2280
16th to endNight
34%27%23%26%5%
2519
December1st to 15thNight
39%212%24%17%3
2423
16th to endNight
44%28%21%18%4
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
23%10%36%20%8%1
90
16th to endDay
7%22%40%20%7%1
96
February1st to 15thDay
10%17%47%17%6%
90
16th to endDay
14%13%43%22%6%
81
March1st to 15thDay
16%20%44%15%3
90
16th to endDay
20%11%34%23%9%
96
April1st to 15thDay
16%11%34%26%10%
204
16th to endDay
23%6%34%19%13%2
288
May1st to 15thDay
16%10%30%29%10%2
468
16th to endDay
13%6%34%26%14%4
517
June1st to 15thDay
9%314%35%29%7%
495
16th to endDay
6%315%37%29%8%
495
July1st to 15thDay
10%114%33%33%7%
475
16th to endDay
5%1323%44%20%
515
August1st to 15thDay
8%15%29%41%12%
493
16th to endDay
8%17%32%38%11%
386
September1st to 15thDay
8%210%27%36%15%
253
16th to endDay
5%8%40%25%20%
135
October1st to 15thDay
12%5%22%37%17%5%
135
16th to endDay
8%8%37%30%11%3
144
November1st to 15thDay
17%6%29%28%15%2
135
16th to endDay
22%15%32%22%5%
135
December1st to 15thDay
18%6%46%20%6%4
100
16th to endDay
18%7%53%17%3
96
January1st to 15thNight
17%15%32%28%5%
900
16th to endNight
13%13%37%30%5%
960
February1st to 15thNight
16%13%38%27%3
880
16th to endNight
15%12%43%24%3
603
March1st to 15thNight
18%9%35%31%5%
540
16th to endNight
19%8%35%27%8%
576
April1st to 15thNight
13%11%38%30%6%
539
16th to endNight
16%440%26%10%
540
May1st to 15thNight
15%6%26%38%14%
540
16th to endNight
11%326%34%22%1
563
June1st to 15thNight
5%415%43%29%1
540
16th to endNight
3117%42%32%2
540
July1st to 15thNight
7%19%44%32%3
510
16th to endNight
3332%52%7%
564
August1st to 15thNight
415%38%42%6%
539
16th to endNight
5%7%42%39%5%
573
September1st to 15thNight
13%9%37%35%3
540
16th to endNight
10%114%37%31%4
537
October1st to 15thNight
11%225%35%20%4
714
16th to endNight
13%5%30%35%14%1
768
November1st to 15thNight
12%9%34%29%14%
760
16th to endNight
17%8%35%27%9%
959
December1st to 15thNight
19%11%33%29%6%
920
16th to endNight
21%9%35%28%4
960
Page generated at 2017-12-05 09:18:58. Version ac04

Copyright 2017 A. Danko


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