Anderson Mesa Station
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Anderson Mesa Station clear sky chart from 2005-11-05 to 2018-02-22.

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
55%
16206
33%
48882
22%
16165
67%
16165
47%
23569

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
49%
780
31%
2522
22%
776
63%
776
41%
1226
January16th to endNight
49%
832
35%
2704
25%
832
64%
832
41%
1335
February1st to 15thNight
49%
760
32%
2419
23%
760
65%
760
48%
1124
February16th to endNight
36%
660
37%
1967
21%
660
56%
660
41%
959
March1st to 15thNight
45%
720
36%
1980
20%
720
60%
720
47%
979
March16th to endNight
47%
768
34%
2112
16%
768
62%
768
50%
1031
April1st to 15thNight
36%
683
28%
1942
11%
683
51%
683
40%
980
April16th to endNight
41%
540
40%
1686
19%
540
63%
540
52%
701
May1st to 15thNight
47%
540
33%
1619
18%
539
61%
539
53%
733
May16th to endNight
45%
561
34%
1684
19%
561
58%
561
53%
747
June1st to 15thNight
48%
540
32%
1620
19%
540
59%
540
61%
689
June16th to endNight
67%
540
33%
1620
26%
540
74%
540
66%
676
July1st to 15thNight
74%
510
20%
1530
15%
510
76%
510
39%
844
July16th to endNight
74%
564
17%
1593
13%
531
76%
531
30%
983
August1st to 15thNight
78%
539
26%
1611
21%
536
79%
536
38%
883
August16th to endNight
77%
593
32%
1814
28%
593
80%
593
44%
943
September1st to 15thNight
73%
720
28%
1980
21%
720
78%
720
48%
1085
September16th to endNight
71%
716
44%
1980
28%
716
81%
716
67%
880
October1st to 15thNight
55%
720
37%
2082
21%
720
69%
720
58%
943
October16th to endNight
62%
768
43%
2304
30%
768
74%
768
56%
1041
November1st to 15thNight
57%
760
35%
2339
23%
760
69%
760
51%
1089
November16th to endNight
54%
780
40%
2535
30%
780
69%
780
51%
1087
December1st to 15thNight
50%
780
33%
2535
22%
780
66%
780
43%
1202
December16th to endNight
45%
832
32%
2704
22%
832
59%
832
35%
1409

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
231442445%7%59%
49371
Night
121232345%7%65%
49078
TransparencyDay
22%5%8%18%28%16%
49066
Night
17%49%19%29%18%
48884
SeeingDay
7%16%26%29%15%4
5901
Night
311%25%31%22%5%
16212

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
214423347%63%
1746
16th to endDay
2225%323447%60%
1872
February1st to 15thDay
142442335%6%60%
1773
16th to endDay
213425%46%9%57%
1651
March1st to 15thDay
121342346%8%61%
1980
16th to endDay
2213323448%63%
2112
April1st to 15thDay
123425%45%7%61%
2006
16th to endDay
1324313246%66%
2271
May1st to 15thDay
2313323246%64%
2331
16th to endDay
2223423445%64%
2429
June1st to 15thDay
1111212245%76%
2340
16th to endDay
12221444372%
2340
July1st to 15thDay
4326%6%47%6%7%8%41%
2340
16th to endDay
7%6%37%8%5%8%7%8%9%26%
2467
August1st to 15thDay
5%5%26%7%5%7%6%7%7%38%
2340
16th to endDay
4325%6%46%7%7%8%43%
2385
September1st to 15thDay
33246%47%7%7%7%45%
1980
16th to endDay
1212213346%69%
1980
October1st to 15thDay
121232233470%
1878
16th to endDay
2212212245%72%
1920
November1st to 15thDay
1231435%6%70%
1848
16th to endDay
2212312235%72%
1755
December1st to 15thDay
131442335%9%60%
1755
16th to endDay
24246%35%45%7%53%
1872
January1st to 15thNight
12134345%5%7%60%
2522
16th to endNight
221342445%5%62%
2704
February1st to 15thNight
21242345%7%65%
2408
16th to endNight
224245%5%9%61%
1967
March1st to 15thNight
312313448%66%
1980
16th to endNight
1112213447%67%
2112
April1st to 15thNight
312423446%65%
1942
16th to endNight
1212336%75%
1686
May1st to 15thNight
11221335%5%72%
1619
16th to endNight
212212335%73%
1684
June1st to 15thNight
1121233378%
1620
16th to endNight
1221224477%
1620
July1st to 15thNight
2313435%6%7%9%51%
1620
16th to endNight
33145%38%8%8%10%39%
1701
August1st to 15thNight
323425%6%8%10%52%
1620
16th to endNight
22442447%10%54%
1814
September1st to 15thNight
2213425%5%7%8%55%
1980
16th to endNight
111111235%78%
1980
October1st to 15thNight
112112345%73%
2082
16th to endNight
12211224473%
2304
November1st to 15thNight
1232345%6%67%
2339
16th to endNight
112323345%71%
2535
December1st to 15thNight
121232345%8%63%
2535
16th to endNight
13245%35%6%7%6%54%
2704

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
20%49%24%32%7%
1747
16th to endDay
20%410%21%34%8%
1872
February1st to 15thDay
23%5%8%24%23%14%
1773
16th to endDay
20%5%10%23%28%11%
1651
March1st to 15thDay
18%5%7%22%34%12%
1980
16th to endDay
19%48%24%30%12%
2112
April1st to 15thDay
20%47%21%32%14%
2006
16th to endDay
18%36%18%36%16%
2271
May1st to 15thDay
18%37%19%34%16%
2331
16th to endDay
20%46%14%36%17%
2432
June1st to 15thDay
10%25%10%30%41%
2340
16th to endDay
14%338%24%45%
2340
July1st to 15thDay
33%8%12%13%11%19%
2201
16th to endDay
43%13%16%12%11%1
2312
August1st to 15thDay
38%8%12%12%15%10%
2325
16th to endDay
32%10%13%16%20%7%
2385
September1st to 15thDay
31%8%12%14%16%16%
1980
16th to endDay
15%36%15%36%23%
1980
October1st to 15thDay
17%35%15%31%26%
1878
16th to endDay
14%35%15%40%19%
1920
November1st to 15thDay
13%37%25%32%16%
1848
16th to endDay
14%35%21%35%19%
1755
December1st to 15thDay
21%411%26%25%10%
1755
16th to endDay
27%5%11%24%23%7%
1872
January1st to 15thNight
20%49%24%32%9%
2522
16th to endNight
21%5%8%19%33%11%
2704
February1st to 15thNight
16%49%24%27%16%
2419
16th to endNight
16%6%10%23%28%14%
1967
March1st to 15thNight
15%47%22%37%12%
1980
16th to endNight
15%410%24%32%13%
2112
April1st to 15thNight
17%5%8%18%34%15%
1942
16th to endNight
11%26%21%37%20%
1686
May1st to 15thNight
13%47%22%31%21%
1620
16th to endNight
13%36%16%39%20%
1685
June1st to 15thNight
11%238%28%45%
1620
16th to endNight
11%145%21%55%
1620
July1st to 15thNight
25%7%13%14%16%21%
1530
16th to endNight
31%11%20%18%12%4
1593
August1st to 15thNight
24%9%14%18%20%13%
1611
16th to endNight
22%6%14%21%24%10%
1814
September1st to 15thNight
21%6%13%19%21%16%
1980
16th to endNight
9%2416%37%29%
1980
October1st to 15thNight
12%27%19%29%28%
2082
16th to endNight
14%35%15%36%25%
2304
November1st to 15thNight
15%47%23%32%16%
2339
16th to endNight
14%37%19%33%22%
2535
December1st to 15thNight
18%5%11%24%25%14%
2535
16th to endNight
24%6%11%24%24%8%
2704

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
8%17%28%27%14%2
135
16th to endDay
6%18%26%27%17%4
144
February1st to 15thDay
6%19%24%28%15%5%
198
16th to endDay
14%31%28%19%5%
264
March1st to 15thDay
7%25%31%22%10%2
270
16th to endDay
8%27%32%21%7%2
288
April1st to 15thDay
10%26%35%16%7%3
269
16th to endDay
9%35%30%16%6%1
270
May1st to 15thDay
6%27%37%19%7%1
288
16th to endDay
6%22%31%28%10%1
330
June1st to 15thDay
5%14%39%25%9%5%
315
16th to endDay
27%28%37%18%5%
315
July1st to 15thDay
7%321%43%18%3
305
16th to endDay
11%114%36%27%8%
327
August1st to 15thDay
7%111%44%25%9%
315
16th to endDay
6%115%38%29%7%
332
September1st to 15thDay
6%425%36%20%6%
315
16th to endDay
7%13%25%31%16%5%
315
October1st to 15thDay
5%21%33%23%13%3
213
16th to endDay
10%9%20%29%23%6%
144
November1st to 15thDay
5%16%25%31%16%5%
135
16th to endDay
8%17%22%33%12%5%
135
December1st to 15thDay
318%31%22%22%1
135
16th to endDay
7%17%23%36%11%4
144
January1st to 15thNight
414%27%27%18%7%
780
16th to endNight
5%15%27%28%18%5%
832
February1st to 15thNight
213%31%30%17%4
764
16th to endNight
422%34%22%14%1
660
March1st to 15thNight
319%28%28%15%4
720
16th to endNight
316%30%33%13%2
768
April1st to 15thNight
422%32%28%9%2
683
16th to endNight
220%32%29%10%3
540
May1st to 15thNight
212%35%34%12%1
540
16th to endNight
314%32%29%17%3
563
June1st to 15thNight
19%37%34%14%1
540
16th to endNight
2323%49%20%1
540
July1st to 15thNight
5%12%42%34%4
510
16th to endNight
5%9%37%42%5%
564
August1st to 15thNight
5%8%32%45%8%
539
16th to endNight
210%33%41%11%
593
September1st to 15thNight
2114%31%41%8%
720
16th to endNight
36%16%30%34%9%
716
October1st to 15thNight
29%31%31%18%6%
720
16th to endNight
46%22%30%27%9%
768
November1st to 15thNight
111%26%34%20%5%
760
16th to endNight
213%26%27%21%8%
780
December1st to 15thNight
413%27%30%20%3
780
16th to endNight
6%16%27%28%16%4
832
Page generated at 2018-02-23 09:21:38. Version ac04

Copyright 2018 A. Danko


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