Amos
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Amos clear sky chart from 2005-11-05 to 2017-09-10.

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
24%
14873
9%
46641
5%
14840
28%
14840
12%
36325

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
13%
900
5%
2685
2%
895
16%
895
6%
2356
January16th to endNight
21%
816
6%
2691
3%
816
24%
816
7%
2270
February1st to 15thNight
21%
704
9%
2287
5%
701
27%
701
10%
1837
February16th to endNight
17%
631
8%
2041
3%
631
24%
631
8%
1678
March1st to 15thNight
22%
720
11%
2040
7%
720
27%
720
12%
1614
March16th to endNight
27%
768
17%
2082
8%
768
33%
768
18%
1528
April1st to 15thNight
23%
718
13%
1796
5%
718
27%
718
17%
1371
April16th to endNight
25%
524
16%
1604
8%
524
34%
524
19%
1129
May1st to 15thNight
30%
360
14%
1440
13%
360
40%
360
15%
985
May16th to endNight
30%
375
9%
1487
7%
374
39%
374
14%
1025
June1st to 15thNight
33%
360
7%
1260
5%
360
36%
360
15%
896
June16th to endNight
40%
360
7%
1260
4%
360
42%
360
22%
818
July1st to 15thNight
36%
340
7%
1190
5%
340
40%
340
20%
780
July16th to endNight
45%
376
9%
1346
12%
354
46%
354
17%
918
August1st to 15thNight
41%
449
8%
1520
7%
447
45%
447
15%
1097
August16th to endNight
38%
612
13%
1758
9%
612
41%
612
23%
1203
September1st to 15thNight
31%
700
10%
1750
4%
700
34%
700
22%
1275
September16th to endNight
31%
657
15%
1822
8%
657
35%
657
21%
1282
October1st to 15thNight
21%
660
11%
1980
7%
660
26%
660
13%
1527
October16th to endNight
18%
704
7%
2191
5%
704
21%
704
8%
1824
November1st to 15thNight
16%
700
8%
2452
5%
700
21%
700
9%
1997
November16th to endNight
12%
720
6%
2520
4%
720
16%
720
6%
2150
December1st to 15thNight
11%
759
4%
2559
0%
759
15%
759
5%
2218
December16th to endNight
14%
960
6%
2880
3%
960
16%
960
5%
2547

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
21%11%47%6%35%445%24%
47994
Night
19%12%5%8%6%35%445%23%
46799
TransparencyDay
61%410%16%7%
47669
Night
62%410%15%6%
46642
SeeingDay
27%13%30%19%7%2
5836
Night
26%11%29%22%8%
14873

By Month

Percentage Cloud Cover NE (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
18%18%9%12%7%237%449%
1253
16th to endDay
15%16%6%11%9%46%8%6%411%
1530
February1st to 15thDay
8%13%7%9%9%6%9%7%6%6%14%
1575
16th to endDay
13%17%6%12%7%4444418%
1431
March1st to 15thDay
16%12%49%6%46%445%26%
1906
16th to endDay
12%14%37%5%36%5%5%431%
2142
April1st to 15thDay
23%13%5%6%43433426%
2158
16th to endDay
20%12%35%5%24336%30%
2358
May1st to 15thDay
20%10%36%5%3445%5%28%
2511
16th to endDay
24%9%35%433335%32%
2624
June1st to 15thDay
22%7%36%425%45%7%28%
2700
16th to endDay
19%7%36%6%35%5%5%7%30%
2700
July1st to 15thDay
20%6%36%6%35%5%6%7%28%
2700
16th to endDay
19%6%26%6%45%5%6%7%27%
2729
August1st to 15thDay
24%9%26%6%35%5%47%24%
2427
16th to endDay
19%8%46%6%445%5%7%27%
2432
September1st to 15thDay
24%7%35%5%35%5%6%5%28%
2098
16th to endDay
25%8%45%424335%31%
1805
October1st to 15thDay
25%12%46%5%3344425%
1650
16th to endDay
34%18%46%6%2333312%
1677
November1st to 15thDay
24%18%6%8%6%33235%17%
1406
16th to endDay
24%20%8%10%8%2424210%
1440
December1st to 15thDay
22%18%9%13%5%34345%10%
1398
16th to endDay
19%19%7%10%9%46%5%439%
1344
January1st to 15thNight
19%17%8%12%8%35%6%4210%
2685
16th to endNight
13%14%7%12%9%48%7%6%5%10%
2691
February1st to 15thNight
10%15%7%10%9%48%45%6%17%
2285
16th to endNight
15%16%6%11%8%35%5%3417%
2041
March1st to 15thNight
17%11%6%9%6%5%6%5%5%421%
2028
16th to endNight
14%11%46%5%35%445%32%
2082
April1st to 15thNight
23%11%47%5%23245%28%
1796
16th to endNight
19%9%45%5%2434436%
1604
May1st to 15thNight
19%8%26%5%345%46%32%
1440
16th to endNight
24%6%25%5%25%5%5%7%30%
1486
June1st to 15thNight
19%7%46%6%345%6%6%29%
1260
16th to endNight
13%5%35%436%5%5%8%38%
1260
July1st to 15thNight
17%5%25%7%345%6%10%31%
1260
16th to endNight
15%5%36%5%45%5%47%35%
1439
August1st to 15thNight
18%7%26%7%35%6%5%6%30%
1530
16th to endNight
14%7%35%435%5%6%8%36%
1758
September1st to 15thNight
20%8%26%5%24346%35%
1750
16th to endNight
22%6%35%423345%37%
1822
October1st to 15thNight
23%10%47%5%3345%5%25%
1980
16th to endNight
28%17%46%5%3343416%
2191
November1st to 15thNight
22%15%5%9%6%44345%19%
2452
16th to endNight
25%18%6%9%6%35%33314%
2520
December1st to 15thNight
20%19%8%12%8%3423411%
2559
16th to endNight
18%19%8%13%7%36%33310%
2880

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
76%38%8%1
1254
16th to endDay
72%47%11%5%
1530
February1st to 15thDay
68%5%7%12%5%
1577
16th to endDay
69%37%15%3
1431
March1st to 15thDay
61%37%15%11%
1917
16th to endDay
54%38%21%9%2
2142
April1st to 15thDay
62%36%14%11%1
2158
16th to endDay
56%39%15%12%1
2358
May1st to 15thDay
55%5%7%17%11%1
2511
16th to endDay
55%49%19%10%
2628
June1st to 15thDay
54%5%10%19%10%
2700
16th to endDay
52%6%9%21%8%
2700
July1st to 15thDay
51%7%14%19%6%
2541
16th to endDay
55%6%12%20%5%
2559
August1st to 15thDay
60%6%13%17%3
2413
16th to endDay
55%6%14%18%5%
2432
September1st to 15thDay
55%6%13%17%6%
2098
16th to endDay
56%412%21%5%
1805
October1st to 15thDay
62%312%12%6%1
1650
16th to endDay
77%47%7%3
1677
November1st to 15thDay
72%311%7%4
1406
16th to endDay
80%37%6%1
1440
December1st to 15thDay
77%36%10%2
1398
16th to endDay
79%36%7%3
1344
January1st to 15thNight
77%47%8%1
2685
16th to endNight
73%47%9%4
2691
February1st to 15thNight
67%39%11%6%
2287
16th to endNight
70%36%14%4
2041
March1st to 15thNight
64%38%12%9%
2040
16th to endNight
54%38%19%12%2
2082
April1st to 15thNight
57%38%17%11%1
1796
16th to endNight
51%37%20%14%1
1604
May1st to 15thNight
52%49%18%13%2
1440
16th to endNight
51%6%10%19%10%1
1488
June1st to 15thNight
52%6%6%20%12%1
1260
16th to endNight
43%6%12%24%12%
1260
July1st to 15thNight
45%6%15%25%6%
1190
16th to endNight
49%6%14%22%6%
1346
August1st to 15thNight
52%8%14%20%4
1520
16th to endNight
44%7%19%23%4
1758
September1st to 15thNight
50%5%16%19%7%
1750
16th to endNight
48%5%14%25%6%
1822
October1st to 15thNight
60%5%12%14%6%
1980
16th to endNight
71%410%11%2
2191
November1st to 15thNight
68%412%11%2
2452
16th to endNight
74%49%9%1
2520
December1st to 15thNight
77%37%9%1
2559
16th to endNight
79%36%7%3
2880

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
35%15%36%8%5%
60
16th to endDay
30%11%36%14%5%1
71
February1st to 15thDay
21%13%44%20%1
90
16th to endDay
30%22%30%15%2
90
March1st to 15thDay
24%18%35%14%7%
270
16th to endDay
21%15%36%18%6%2
288
April1st to 15thDay
30%17%26%16%7%1
270
16th to endDay
27%17%29%15%7%2
270
May1st to 15thDay
29%12%24%23%6%2
288
16th to endDay
31%10%31%18%5%2
337
June1st to 15thDay
28%11%30%21%6%1
495
16th to endDay
21%13%31%22%9%1
495
July1st to 15thDay
21%12%31%23%9%1
475
16th to endDay
19%11%35%23%9%2
400
August1st to 15thDay
29%6%25%21%10%7%
313
16th to endDay
25%9%26%20%12%4
332
September1st to 15thDay
23%12%27%21%11%3
294
16th to endDay
27%10%30%19%9%2
254
October1st to 15thDay
27%14%34%13%7%1
255
16th to endDay
40%15%20%16%5%1
245
November1st to 15thDay
31%26%31%10%
60
16th to endDay
53%8%28%8%1
60
December1st to 15thDay
31%11%41%10%5%
60
16th to endDay
35%14%35%12%1
64
January1st to 15thNight
31%13%29%20%5%
900
16th to endNight
22%12%32%21%10%
816
February1st to 15thNight
18%11%34%25%8%
704
16th to endNight
24%11%34%23%5%
631
March1st to 15thNight
25%19%28%21%5%
720
16th to endNight
20%14%34%22%7%1
768
April1st to 15thNight
29%15%26%22%5%
718
16th to endNight
23%10%35%24%5%
524
May1st to 15thNight
25%10%30%25%8%
360
16th to endNight
28%8%28%27%7%
375
June1st to 15thNight
23%8%29%28%10%
360
16th to endNight
16%5%31%33%12%1
360
July1st to 15thNight
20%7%30%30%10%
340
16th to endNight
17%6%25%36%14%
376
August1st to 15thNight
22%5%23%24%20%2
449
16th to endNight
19%6%30%27%13%1
612
September1st to 15thNight
26%9%28%23%11%2
700
16th to endNight
24%11%26%25%10%1
657
October1st to 15thNight
29%14%28%19%7%
660
16th to endNight
40%11%25%15%6%
704
November1st to 15thNight
31%14%30%15%7%
700
16th to endNight
36%14%28%16%3
720
December1st to 15thNight
33%13%30%17%4
759
16th to endNight
31%13%27%19%6%1
960
Page generated at 2017-09-11 19:35:33. Version ac04

Copyright 2017 A. Danko


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