The Shoals
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Shoals clear sky chart from 2005-11-06 to 2024-01-11.

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
52%
23711
23%
74197
19%
23657
58%
23657
29%
45262

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 10thNight
31%
950
22%
2648
11%
946
41%
946
27%
1727
January11th to 20thNight
29%
849
20%
2387
10%
849
37%
849
21%
1695
January21st to endNight
31%
792
29%
2376
14%
792
45%
792
27%
1504
February1st to 10thNight
31%
720
21%
2160
11%
720
40%
720
23%
1447
February11th to 20thNight
29%
703
17%
2098
9%
699
36%
699
21%
1426
February21st to endNight
26%
592
21%
1776
10%
592
34%
592
21%
1232
March1st to 10thNight
37%
720
22%
2160
13%
720
44%
720
28%
1357
March11th to 20thNight
35%
720
18%
2111
11%
720
41%
720
25%
1400
March21st to endNight
40%
612
23%
1998
14%
612
49%
612
26%
1249
April1st to 10thNight
45%
540
26%
1800
20%
540
55%
540
31%
1032
April11th to 20thNight
49%
533
28%
1775
23%
533
60%
533
33%
994
April21st to endNight
51%
540
24%
1800
20%
540
59%
540
32%
1025
May1st to 10thNight
55%
540
23%
1684
19%
540
62%
540
34%
974
May11th to 20thNight
60%
531
21%
1592
17%
531
63%
531
31%
963
May21st to endNight
71%
582
21%
1744
19%
582
73%
582
37%
1001
June1st to 10thNight
70%
540
20%
1612
18%
540
71%
540
34%
969
June11th to 20thNight
81%
540
25%
1440
22%
540
82%
540
48%
804
June21st to endNight
77%
540
24%
1440
20%
540
78%
540
42%
842
July1st to 10thNight
75%
525
16%
1400
15%
525
76%
525
33%
914
July11th to 20thNight
78%
522
19%
1428
18%
522
79%
522
38%
868
July21st to endNight
75%
591
17%
1744
18%
558
76%
558
31%
1061
August1st to 10thNight
81%
537
19%
1778
23%
534
81%
534
35%
972
August11th to 20thNight
75%
534
16%
1776
19%
534
75%
534
29%
1050
August21st to endNight
72%
594
22%
1980
26%
594
72%
594
29%
1188
September1st to 10thNight
74%
540
26%
1800
27%
540
75%
540
34%
1007
September11th to 20thNight
67%
691
24%
1951
21%
691
68%
691
33%
1196
September21st to endNight
67%
720
32%
1980
25%
720
70%
720
42%
1135
October1st to 10thNight
70%
720
33%
1980
29%
720
72%
720
45%
1097
October11th to 20thNight
56%
720
31%
2060
25%
720
62%
720
36%
1214
October21st to endNight
53%
792
30%
2478
26%
792
60%
792
33%
1453
November1st to 10thNight
58%
740
29%
2406
29%
740
63%
740
35%
1336
November11th to 20thNight
48%
760
29%
2470
24%
760
57%
760
33%
1388
November21st to endNight
46%
760
26%
2470
22%
760
52%
760
28%
1479
December1st to 10thNight
38%
760
23%
2470
17%
760
48%
760
22%
1602
December11th to 20thNight
40%
759
27%
2896
20%
758
49%
758
24%
1696
December21st to endNight
31%
902
13%
4529
11%
893
40%
893
13%
2965

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%6%35%5%35%5%6%8%42%
75006
Night
12%6%35%5%345%5%7%45%
74677
TransparencyDay
39%5%11%22%18%4
74724
Night
37%5%11%22%20%5%
74479
SeeingDay
13%6%20%24%23%14%
13935
Night
15%5%21%32%23%4
23724

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 10thDay
18%8%36%433446%42%
1517
11th to 20thDay
21%8%45%5%3345%6%37%
1576
21st to endDay
16%5%25%5%2445%6%46%
1980
February1st to 10thDay
19%9%46%433346%39%
1800
11th to 20thDay
20%8%37%5%34345%38%
1748
21st to endDay
21%9%36%433346%38%
1480
March1st to 10thDay
15%7%37%5%4445%6%41%
1800
11th to 20thDay
17%8%36%6%3446%7%36%
1847
21st to endDay
14%8%36%6%46%5%5%7%37%
2371
April1st to 10thDay
12%5%345%345%6%7%46%
2160
11th to 20thDay
14%5%35%5%3446%6%46%
2134
21st to endDay
10%5%35%5%345%6%9%45%
2160
May1st to 10thDay
13%5%35%5%345%5%7%45%
2276
11th to 20thDay
10%6%37%6%45%6%6%6%41%
2301
21st to endDay
9%5%36%6%36%5%7%10%41%
2531
June1st to 10thDay
8%6%36%6%35%7%7%9%41%
2341
11th to 20thDay
43246%47%7%7%11%45%
2520
21st to endDay
5%4246%46%8%7%11%43%
2520
July1st to 10thDay
7%5%36%8%5%7%7%9%11%32%
2520
11th to 20thDay
8%5%25%7%46%7%8%11%36%
2480
21st to endDay
5%5%36%7%47%7%8%11%37%
2467
August1st to 10thDay
4326%7%47%8%10%12%37%
2148
11th to 20thDay
7%6%26%7%46%6%7%10%37%
2125
21st to endDay
11%7%36%6%46%6%6%9%37%
2376
September1st to 10thDay
10%5%25%6%45%5%6%8%44%
2160
11th to 20thDay
12%5%26%5%45%5%6%7%44%
1990
21st to endDay
9%5%2444445%7%53%
1980
October1st to 10thDay
10%5%2443445%6%54%
1980
11th to 20thDay
9%5%25%43445%6%54%
1895
21st to endDay
15%6%25%33345%6%50%
1877
November1st to 10thDay
11%424424445%56%
1672
11th to 20thDay
12%5%24433445%52%
1710
21st to endDay
15%6%26%5%346%46%44%
1710
December1st to 10thDay
20%9%36%5%3445%6%35%
1710
11th to 20thDay
16%8%35%6%34445%42%
2153
21st to endDay
14%9%37%7%35%6%6%7%33%
2991
January1st to 10thNight
19%8%35%424445%44%
2648
11th to 20thNight
18%10%46%5%245%5%6%35%
2387
21st to endNight
15%7%36%424446%45%
2376
February1st to 10thNight
18%9%46%5%34346%40%
2160
11th to 20thNight
20%8%35%5%24345%40%
2098
21st to endNight
24%7%35%5%34445%36%
1776
March1st to 10thNight
16%5%345%2445%6%45%
2160
11th to 20thNight
16%7%35%5%34448%39%
2111
21st to endNight
14%6%35%6%346%5%6%43%
1998
April1st to 10thNight
11%5%26%43445%8%48%
1800
11th to 20thNight
14%4244335%5%7%50%
1775
21st to endNight
11%4345%345%6%8%47%
1800
May1st to 10thNight
10%5%25%42446%8%50%
1684
11th to 20thNight
9%5%25%6%35%5%6%10%44%
1592
21st to endNight
5%5%25%5%35%5%7%11%47%
1744
June1st to 10thNight
5%5%26%6%45%5%6%10%46%
1612
11th to 20thNight
32235%35%6%7%11%55%
1440
21st to endNight
44245%25%47%11%52%
1440
July1st to 10thNight
5%435%5%46%6%9%11%41%
1440
11th to 20thNight
6%4345%35%6%8%13%43%
1476
21st to endNight
45%36%5%47%7%8%13%39%
1847
August1st to 10thNight
33146%45%7%9%11%46%
1790
11th to 20thNight
5%425%5%46%7%7%12%43%
1776
21st to endNight
8%435%6%45%5%6%8%44%
1980
September1st to 10thNight
9%4243345%6%9%50%
1800
11th to 20thNight
10%5%25%5%345%6%8%47%
1951
21st to endNight
8%4235%24346%57%
1980
October1st to 10thNight
8%314424445%61%
1980
11th to 20thNight
11%6%25%433345%53%
2060
21st to endNight
15%7%24423345%51%
2478
November1st to 10thNight
11%42442335%6%54%
2406
11th to 20thNight
12%5%25%42445%6%52%
2470
21st to endNight
16%6%34423445%48%
2470
December1st to 10thNight
19%8%3443445%7%39%
2470
11th to 20thNight
17%6%2442345%6%48%
3042
21st to endNight
15%9%37%6%45%6%6%7%32%
4660

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 10thDay
45%27%21%20%4
1518
11th to 20thDay
50%37%19%18%3
1576
21st to endDay
39%37%25%23%3
1980
February1st to 10thDay
48%38%19%19%4
1800
11th to 20thDay
50%36%21%16%4
1758
21st to endDay
49%28%15%19%7%
1480
March1st to 10thDay
44%47%17%19%9%
1800
11th to 20thDay
47%5%11%17%17%3
1847
21st to endDay
46%5%11%21%16%1
2371
April1st to 10thDay
37%410%25%18%6%
2160
11th to 20thDay
38%47%21%24%6%
2134
21st to endDay
36%5%9%29%19%2
2160
May1st to 10thDay
38%5%11%25%17%4
2276
11th to 20thDay
41%5%15%23%15%1
2305
21st to endDay
37%5%16%25%15%2
2531
June1st to 10thDay
37%6%15%23%18%2
2341
11th to 20thDay
30%7%15%27%19%2
2520
21st to endDay
31%9%16%23%17%4
2520
July1st to 10thDay
40%9%19%19%11%3
2451
11th to 20thDay
38%8%22%21%10%2
2405
21st to endDay
37%9%19%25%10%1
2329
August1st to 10thDay
35%10%20%24%10%1
2136
11th to 20thDay
40%7%16%20%15%2
2125
21st to endDay
43%7%12%23%11%3
2376
September1st to 10thDay
38%7%14%20%18%4
2160
11th to 20thDay
38%6%12%17%23%4
1990
21st to endDay
31%5%9%26%22%7%
1980
October1st to 10thDay
31%47%24%26%6%
1980
11th to 20thDay
31%48%22%26%9%
1895
21st to endDay
36%45%18%29%8%
1877
November1st to 10thDay
31%47%20%30%8%
1672
11th to 20thDay
35%46%19%28%8%
1710
21st to endDay
42%46%21%22%5%
1710
December1st to 10thDay
50%47%18%17%4
1710
11th to 20thDay
45%47%22%19%4
2150
21st to endDay
47%5%10%21%14%3
2991
January1st to 10thNight
44%38%22%20%4
2648
11th to 20thNight
50%46%20%16%3
2387
21st to endNight
42%36%24%21%5%
2376
February1st to 10thNight
48%38%20%18%4
2160
11th to 20thNight
49%37%18%18%6%
2099
21st to endNight
50%46%17%17%7%
1776
March1st to 10thNight
40%48%17%20%10%
2160
11th to 20thNight
44%410%20%17%4
2111
21st to endNight
41%5%9%24%18%3
1998
April1st to 10thNight
35%411%25%20%5%
1800
11th to 20thNight
33%49%22%23%10%
1775
21st to endNight
34%412%25%21%3
1800
May1st to 10thNight
33%5%11%23%24%4
1684
11th to 20thNight
35%6%16%23%18%2
1593
21st to endNight
29%7%16%28%16%3
1745
June1st to 10thNight
33%6%15%23%20%3
1612
11th to 20thNight
22%7%18%31%20%3
1440
21st to endNight
26%8%15%29%19%4
1440
July1st to 10thNight
33%10%20%23%11%3
1400
11th to 20thNight
29%8%22%27%11%3
1428
21st to endNight
31%10%21%24%12%1
1744
August1st to 10thNight
26%9%21%30%13%1
1778
11th to 20thNight
32%10%22%20%13%3
1776
21st to endNight
36%7%17%24%12%5%
1980
September1st to 10thNight
30%7%15%24%20%5%
1800
11th to 20thNight
35%6%14%17%25%4
1951
21st to endNight
28%48%27%23%9%
1980
October1st to 10thNight
26%47%24%28%11%
1980
11th to 20thNight
34%36%21%25%10%
2060
21st to endNight
36%35%20%28%9%
2478
November1st to 10thNight
32%46%22%25%11%
2406
11th to 20thNight
34%37%19%27%10%
2470
21st to endNight
39%37%21%24%7%
2470
December1st to 10thNight
45%48%21%19%3
2470
11th to 20thNight
39%36%22%26%4
3044
21st to endNight
49%5%8%20%14%3
4660

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 10thDay
22%16%34%21%7%
270
11th to 20thDay
25%14%39%14%6%3
240
21st to endDay
18%14%43%19%6%
264
February1st to 10thDay
21%13%37%22%6%1
240
11th to 20thDay
33%14%34%17%21
240
21st to endDay
32%12%36%14%7%
198
March1st to 10thDay
21%14%33%23%8%1
240
11th to 20thDay
20%16%33%24%6%1
287
21st to endDay
21%13%29%25%11%
462
April1st to 10thDay
17%10%29%28%15%1
420
11th to 20thDay
16%12%26%27%16%2
412
21st to endDay
13%9%24%32%16%5%
420
May1st to 10thDay
15%9%22%29%17%7%
423
11th to 20thDay
11%320%29%21%16%
447
21st to endDay
10%215%26%26%21%
485
June1st to 10thDay
11%312%23%26%25%
451
11th to 20thDay
5%113%25%32%24%
630
21st to endDay
7%214%26%32%20%
630
July1st to 10thDay
8%19%26%29%27%
621
11th to 20thDay
8%28%20%27%34%
578
21st to endDay
5%7%19%35%33%
488
August1st to 10thDay
6%28%20%36%28%
446
11th to 20thDay
9%17%19%44%20%
439
21st to endDay
13%27%16%35%27%
495
September1st to 10thDay
9%110%17%41%22%
450
11th to 20thDay
11%10%20%34%25%
450
21st to endDay
12%213%25%35%14%
450
October1st to 10thDay
10%214%30%30%14%
450
11th to 20thDay
9%8%27%34%18%4
365
21st to endDay
20%10%24%25%17%5%
297
November1st to 10thDay
17%8%23%26%20%6%
270
11th to 20thDay
10%10%36%32%11%1
270
21st to endDay
16%13%28%23%16%4
270
December1st to 10thDay
24%16%29%21%9%1
270
11th to 20thDay
17%13%34%23%11%1
270
21st to endDay
21%16%35%21%8%
297
January1st to 10thNight
22%10%33%29%6%
950
11th to 20thNight
23%9%34%27%7%
849
21st to endNight
18%7%40%31%4
792
February1st to 10thNight
21%9%33%31%6%
720
11th to 20thNight
24%12%30%31%3
703
21st to endNight
26%10%35%27%2
592
March1st to 10thNight
19%8%32%36%5%
720
11th to 20thNight
20%7%33%31%9%1
720
21st to endNight
15%8%32%31%13%
612
April1st to 10thNight
13%7%31%35%14%
540
11th to 20thNight
14%6%27%38%14%2
533
21st to endNight
12%6%26%39%16%1
540
May1st to 10thNight
11%325%39%21%2
540
11th to 20thNight
10%317%38%27%5%
531
21st to endNight
7%110%37%38%7%
584
June1st to 10thNight
6%19%36%40%7%
540
11th to 20thNight
47%32%48%8%
540
21st to endNight
417%34%43%11%
540
July1st to 10thNight
8%6%25%46%15%
525
11th to 20thNight
7%1424%49%15%
522
21st to endNight
5%16%26%46%17%
591
August1st to 10thNight
41422%55%15%
537
11th to 20thNight
6%1427%52%9%
534
21st to endNight
10%15%22%51%10%
594
September1st to 10thNight
11%18%25%48%7%
540
11th to 20thNight
11%211%29%41%7%
691
21st to endNight
12%112%31%40%4
720
October1st to 10thNight
9%213%36%34%6%
720
11th to 20thNight
14%420%39%21%3
720
21st to endNight
17%5%19%36%21%2
792
November1st to 10thNight
12%420%40%21%2
740
11th to 20thNight
13%5%29%38%14%1
760
21st to endNight
18%8%24%37%13%1
760
December1st to 10thNight
21%9%28%32%9%
760
11th to 20thNight
21%6%30%33%10%
760
21st to endNight
25%8%29%33%5%
912
Page generated at 2024-01-08 10:14:17. Version ac07

Copyright 2024 Attilla Danko


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