Ammon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ammon clear sky chart from 2005-11-05 to 2017-10-16.

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
51%
15611
19%
47090
16%
15572
55%
15572
28%
29760

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
38%
752
10%
2542
9%
752
40%
752
15%
1858
January16th to endNight
42%
768
12%
2518
12%
768
45%
768
17%
1817
February1st to 15thNight
42%
700
9%
2288
9%
697
44%
697
17%
1655
February16th to endNight
39%
632
12%
1944
11%
632
43%
632
19%
1395
March1st to 15thNight
44%
720
13%
2037
10%
720
48%
720
22%
1458
March16th to endNight
41%
768
16%
2112
9%
768
45%
768
24%
1476
April1st to 15thNight
44%
630
16%
1815
10%
630
49%
630
25%
1207
April16th to endNight
47%
540
21%
1620
16%
540
50%
540
28%
1017
May1st to 15thNight
53%
539
19%
1619
16%
539
56%
539
33%
970
May16th to endNight
55%
561
17%
1571
15%
561
58%
561
31%
1008
June1st to 15thNight
55%
405
18%
1305
15%
405
61%
405
34%
726
June16th to endNight
70%
360
30%
1260
32%
360
78%
360
54%
530
July1st to 15thNight
80%
340
25%
1257
31%
340
86%
340
52%
519
July16th to endNight
78%
517
30%
1546
32%
484
81%
484
59%
677
August1st to 15thNight
77%
539
29%
1611
25%
536
80%
536
50%
798
August16th to endNight
73%
573
39%
1719
31%
573
77%
573
55%
804
September1st to 15thNight
69%
660
30%
1905
23%
660
76%
660
49%
983
September16th to endNight
67%
716
33%
1980
26%
716
71%
716
45%
1099
October1st to 15thNight
58%
720
25%
2106
19%
720
62%
720
38%
1187
October16th to endNight
58%
708
25%
2176
22%
708
63%
708
32%
1302
November1st to 15thNight
49%
703
20%
2278
20%
703
52%
703
25%
1445
November16th to endNight
43%
900
15%
2520
10%
900
47%
900
24%
1718
December1st to 15thNight
36%
900
8%
2520
5%
900
39%
900
17%
1898
December16th to endNight
33%
960
9%
2841
6%
960
36%
960
14%
2213

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
8%6%25%42445%6%48%
48331
Night
9%8%35%42445%6%44%
47270
TransparencyDay
37%410%21%17%8%
48010
Night
40%412%21%14%7%
47091
SeeingDay
12%11%24%27%18%5%
5882
Night
14%5%19%35%20%3
15622

By Month

Percentage Cloud Cover SW (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
14%13%5%8%5%34447%28%
1405
16th to endDay
16%13%5%7%42444431%
1704
February1st to 15thDay
12%12%39%6%35%5%45%30%
1575
16th to endDay
8%12%48%6%35%5%5%7%33%
1528
March1st to 15thDay
7%11%48%6%36%448%34%
1923
16th to endDay
11%12%47%6%35%5%5%6%31%
2112
April1st to 15thDay
9%10%36%5%35%5%6%8%36%
2131
16th to endDay
9%7%35%5%245%5%7%42%
2340
May1st to 15thDay
7%5%25%4245%5%8%47%
2331
16th to endDay
10%7%35%5%345%6%8%39%
2540
June1st to 15thDay
9%425%5%25%5%5%8%45%
2652
16th to endDay
222222336%71%
2700
July1st to 15thDay
211231335%8%66%
2624
16th to endDay
322223445%68%
2513
August1st to 15thDay
2212323346%66%
2340
16th to endDay
2212223345%68%
2483
September1st to 15thDay
4312212346%67%
2052
16th to endDay
7%212313346%62%
1980
October1st to 15thDay
11%5%13424445%50%
1854
16th to endDay
9%6%246%3445%7%45%
1715
November1st to 15thDay
11%9%45%433345%43%
1569
16th to endDay
12%9%46%434446%38%
1440
December1st to 15thDay
15%12%5%9%6%245%45%27%
1440
16th to endDay
15%14%5%7%6%25%45%6%25%
1380
January1st to 15thNight
16%13%47%5%23347%30%
2542
16th to endNight
15%15%5%6%423345%32%
2518
February1st to 15thNight
13%13%5%6%5%35%45%6%31%
2277
16th to endNight
10%11%5%6%6%446%5%6%32%
1944
March1st to 15thNight
7%10%46%7%45%5%5%6%35%
2037
16th to endNight
10%9%47%5%3446%7%36%
2112
April1st to 15thNight
9%8%36%5%35%5%6%7%39%
1815
16th to endNight
10%8%24433446%46%
1620
May1st to 15thNight
6%6%244345%5%9%47%
1619
16th to endNight
10%5%245%245%6%7%45%
1570
June1st to 15thNight
7%413425%47%8%48%
1305
16th to endNight
2113122247%69%
1260
July1st to 15thNight
11112135%6%9%64%
1333
16th to endNight
1111222447%69%
1653
August1st to 15thNight
22232445%8%62%
1620
16th to endNight
2212322347%68%
1719
September1st to 15thNight
4212223346%64%
1905
16th to endNight
7%313323346%59%
1980
October1st to 15thNight
9%424324345%55%
2106
16th to endNight
10%5%245%2245%6%49%
2176
November1st to 15thNight
13%8%35%323346%45%
2278
16th to endNight
9%10%46%5%25%446%39%
2520
December1st to 15thNight
14%11%48%7%33445%30%
2520
16th to endNight
18%17%5%7%5%3433426%
2841

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
55%5%19%13%5%
1405
16th to endDay
56%5%14%18%41
1704
February1st to 15thDay
56%5%15%18%5%
1575
16th to endDay
53%6%12%20%5%
1528
March1st to 15thDay
51%5%14%21%6%1
1923
16th to endDay
54%411%20%7%
2112
April1st to 15thDay
46%6%14%20%11%
2131
16th to endDay
42%5%10%27%13%1
2340
May1st to 15thDay
36%5%7%29%18%1
2331
16th to endDay
43%6%10%25%12%1
2543
June1st to 15thDay
37%49%27%17%3
2652
16th to endDay
16%3421%37%17%
2700
July1st to 15thDay
17%3419%32%23%
2471
16th to endDay
19%2313%24%36%
2357
August1st to 15thDay
20%3314%30%27%
2325
16th to endDay
19%3320%32%21%
2483
September1st to 15thDay
20%37%20%32%15%
2052
16th to endDay
24%38%28%25%8%
1980
October1st to 15thDay
36%312%32%11%3
1854
16th to endDay
39%314%26%15%
1715
November1st to 15thDay
44%415%22%9%2
1569
16th to endDay
47%219%21%6%1
1440
December1st to 15thDay
59%5%13%16%4
1440
16th to endDay
61%5%16%12%3
1380
January1st to 15thNight
55%6%17%15%41
2542
16th to endNight
54%414%18%5%1
2518
February1st to 15thNight
54%5%16%17%5%
2288
16th to endNight
51%5%15%19%5%1
1944
March1st to 15thNight
49%5%13%22%7%1
2037
16th to endNight
47%5%13%24%8%
2112
April1st to 15thNight
43%5%15%23%10%1
1815
16th to endNight
39%411%27%16%
1620
May1st to 15thNight
35%49%29%20%2
1620
16th to endNight
38%411%26%15%2
1571
June1st to 15thNight
30%5%12%24%23%4
1305
16th to endNight
16%25%16%37%22%
1260
July1st to 15thNight
15%45%19%27%28%
1257
16th to endNight
14%2313%26%39%
1546
August1st to 15thNight
20%3416%25%29%
1611
16th to endNight
18%2417%29%28%
1719
September1st to 15thNight
22%35%15%33%20%
1905
16th to endNight
26%35%27%27%9%
1980
October1st to 15thNight
32%212%31%17%3
2106
16th to endNight
35%410%29%17%2
2176
November1st to 15thNight
42%413%25%11%3
2278
16th to endNight
46%416%21%9%1
2520
December1st to 15thNight
55%5%19%14%4
2520
16th to endNight
62%314%14%3
2841

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
31%5%8%30%20%5%
60
16th to endDay
28%217%31%17%3
92
February1st to 15thDay
25%12%18%16%21%5%
90
16th to endDay
17%21%30%18%9%2
187
March1st to 15thDay
17%27%27%22%6%
270
16th to endDay
20%24%32%15%6%
288
April1st to 15thDay
15%23%26%19%11%3
269
16th to endDay
17%15%32%21%10%1
270
May1st to 15thDay
10%12%32%25%13%4
288
16th to endDay
16%7%19%29%19%8%
441
June1st to 15thDay
10%11%22%29%19%5%
495
16th to endDay
5%7%25%30%24%7%
495
July1st to 15thDay
45%17%33%33%6%
405
16th to endDay
35%25%40%22%3
327
August1st to 15thDay
6%427%31%25%4
315
16th to endDay
36%24%30%23%11%
332
September1st to 15thDay
6%6%24%27%24%10%
315
16th to endDay
11%9%22%28%20%7%
315
October1st to 15thDay
14%13%21%24%21%5%
189
16th to endDay
17%15%18%22%21%6%
99
November1st to 15thDay
13%118%23%25%17%
90
16th to endDay
22%11%31%27%6%1
90
December1st to 15thDay
27%13%25%27%5%
90
16th to endDay
24%125%32%7%8%
70
January1st to 15thNight
23%6%17%30%18%2
756
16th to endNight
24%5%14%33%19%3
768
February1st to 15thNight
21%6%19%33%17%2
704
16th to endNight
16%9%25%31%13%3
632
March1st to 15thNight
13%8%24%35%14%3
720
16th to endNight
14%9%26%35%12%1
768
April1st to 15thNight
13%8%26%33%15%2
630
16th to endNight
15%8%22%35%16%2
540
May1st to 15thNight
10%5%23%35%22%2
540
16th to endNight
12%6%17%36%23%4
563
June1st to 15thNight
10%5%24%34%23%2
405
16th to endNight
4319%38%27%6%
360
July1st to 15thNight
212%41%36%6%
340
16th to endNight
2112%42%35%5%
517
August1st to 15thNight
6%110%44%34%2
539
16th to endNight
3215%40%33%5%
573
September1st to 15thNight
6%215%33%33%7%
660
16th to endNight
9%214%35%28%9%
716
October1st to 15thNight
12%5%18%36%22%3
720
16th to endNight
13%415%40%20%5%
708
November1st to 15thNight
17%6%21%32%19%2
703
16th to endNight
14%9%23%32%17%2
900
December1st to 15thNight
22%7%22%34%12%1
900
16th to endNight
28%8%18%29%13%2
960
Page generated at 2017-10-17 13:35:17. Version ac04

Copyright 2017 A. Danko


Ammon Clear Sky Chart |Charts Home