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 2018-03-11.

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
23%
15639
9%
49047
5%
15606
28%
15606
12%
38268

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
14%
975
5%
2910
2%
970
16%
970
6%
2546
January16th to endNight
21%
884
6%
2915
3%
884
25%
884
7%
2458
February1st to 15thNight
22%
764
10%
2482
5%
761
28%
761
10%
1984
February16th to endNight
17%
683
8%
2209
4%
683
23%
683
9%
1810
March1st to 15thNight
21%
764
11%
2166
7%
764
26%
764
12%
1722
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%
720
10%
1800
4%
720
34%
720
22%
1308
September16th to endNight
32%
717
15%
1988
8%
717
36%
717
20%
1408
October1st to 15thNight
22%
720
11%
2160
8%
720
26%
720
14%
1638
October16th to endNight
17%
768
8%
2390
5%
768
22%
768
9%
1979
November1st to 15thNight
15%
760
7%
2662
5%
760
20%
760
8%
2175
November16th to endNight
12%
780
6%
2730
3%
780
16%
780
6%
2322
December1st to 15thNight
12%
822
4%
2772
0%
822
16%
822
5%
2406
December16th to endNight
15%
1040
6%
3120
4%
1040
17%
1040
5%
2762

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
20%11%47%6%35%445%24%
49587
Night
18%12%5%8%6%35%445%23%
49205
TransparencyDay
61%49%15%7%
49262
Night
62%410%15%6%
49048
SeeingDay
26%13%31%18%7%2
6349
Night
26%12%29%22%8%
15639

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%8%12%8%337%5%49%
1358
16th to endDay
14%16%6%11%9%46%8%6%411%
1658
February1st to 15thDay
8%13%7%9%10%6%9%7%6%7%14%
1710
16th to endDay
14%17%6%12%7%3444418%
1549
March1st to 15thDay
15%14%5%9%6%36%435%25%
2017
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
23%7%35%435%5%6%5%29%
2160
16th to endDay
24%8%45%5%24345%31%
1968
October1st to 15thDay
24%11%36%5%33445%27%
1800
16th to endDay
33%17%46%6%2333314%
1830
November1st to 15thDay
23%19%7%8%6%3323416%
1526
16th to endDay
25%20%8%9%8%3434210%
1560
December1st to 15thDay
21%17%9%13%5%34445%10%
1514
16th to endDay
18%18%7%11%10%46%4339%
1456
January1st to 15thNight
19%17%7%12%8%35%6%4310%
2910
16th to endNight
13%14%7%12%9%48%7%6%5%11%
2915
February1st to 15thNight
9%14%6%10%9%48%5%5%6%18%
2480
16th to endNight
15%16%6%11%8%35%5%3418%
2209
March1st to 15thNight
17%12%6%9%6%5%6%5%5%421%
2154
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%24446%35%
1800
16th to endNight
22%7%35%5%23345%37%
1988
October1st to 15thNight
22%9%37%5%3345%5%27%
2160
16th to endNight
28%17%46%5%3344417%
2390
November1st to 15thNight
21%16%5%9%7%44345%18%
2662
16th to endNight
25%18%6%9%6%25%43314%
2730
December1st to 15thNight
19%18%8%12%7%4433411%
2772
16th to endNight
17%19%8%14%8%35%33310%
3120

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
1359
16th to endDay
72%46%10%5%
1658
February1st to 15thDay
67%5%8%13%5%
1712
16th to endDay
69%37%15%4
1549
March1st to 15thDay
62%37%14%11%
2028
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
54%6%13%17%6%
2160
16th to endDay
55%5%11%21%5%
1968
October1st to 15thDay
60%412%14%7%1
1800
16th to endDay
75%37%8%3
1830
November1st to 15thDay
73%311%7%4
1526
16th to endDay
80%37%6%1
1560
December1st to 15thDay
76%36%10%2
1514
16th to endDay
79%35%7%3
1456
January1st to 15thNight
76%5%7%8%1
2910
16th to endNight
72%5%7%9%4
2915
February1st to 15thNight
66%49%12%6%
2482
16th to endNight
69%36%14%4
2209
March1st to 15thNight
65%38%12%9%
2166
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
49%5%16%19%8%
1800
16th to endNight
49%5%14%24%5%
1988
October1st to 15thNight
57%5%13%15%6%
2160
16th to endNight
70%410%11%3
2390
November1st to 15thNight
68%412%10%2
2662
16th to endNight
74%49%9%2
2730
December1st to 15thNight
77%37%9%2
2772
16th to endNight
79%36%7%3
3120

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
34%15%32%13%31
90
16th to endDay
27%18%32%13%6%1
107
February1st to 15thDay
17%17%46%17%
135
16th to endDay
33%23%30%10%2
130
March1st to 15thDay
24%18%36%14%6%
312
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
22%12%30%21%11%2
315
16th to endDay
26%9%30%21%9%2
314
October1st to 15thDay
26%16%34%12%7%1
315
16th to endDay
39%15%22%15%4
302
November1st to 15thDay
33%26%30%10%
90
16th to endDay
53%11%27%6%1
90
December1st to 15thDay
25%15%40%13%5%
90
16th to endDay
28%13%34%17%5%1
96
January1st to 15thNight
30%13%29%20%5%
975
16th to endNight
22%12%31%22%9%
884
February1st to 15thNight
18%11%34%27%8%
764
16th to endNight
23%13%33%22%5%
683
March1st to 15thNight
25%19%28%20%4
764
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
25%9%28%23%11%1
720
16th to endNight
24%11%26%25%11%1
717
October1st to 15thNight
28%13%29%20%7%
720
16th to endNight
39%11%26%15%6%
768
November1st to 15thNight
31%14%31%14%7%
760
16th to endNight
36%15%28%16%3
780
December1st to 15thNight
32%13%30%17%4
822
16th to endNight
29%13%27%20%6%2
1040
Page generated at 2018-03-12 13:28:03. Version ac04

Copyright 2018 A. Danko


Amos Clear Sky Chart |Charts Home