LVAAS South Mountain Campus
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the LVAAS South Mountain Campus clear sky chart from 2005-11-05 to 2018-02-14.

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
33%
15655
19%
48816
10%
15622
44%
15622
22%
31189

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
19%
780
19%
2716
7%
776
35%
776
16%
1733
January16th to endNight
18%
832
22%
2744
6%
832
37%
832
18%
1752
February1st to 15thNight
14%
760
17%
2452
4%
757
31%
757
16%
1607
February16th to endNight
16%
631
25%
1893
7%
631
37%
631
19%
1199
March1st to 15thNight
21%
720
20%
2092
7%
720
35%
720
19%
1370
March16th to endNight
22%
768
22%
2032
8%
768
34%
768
24%
1353
April1st to 15thNight
22%
718
17%
1796
4%
718
28%
718
24%
1215
April16th to endNight
29%
720
18%
1800
5%
720
36%
720
28%
1203
May1st to 15thNight
31%
486
17%
1566
9%
486
39%
486
20%
1040
May16th to endNight
45%
374
16%
1497
14%
374
52%
374
19%
934
June1st to 15thNight
43%
360
15%
1440
12%
360
54%
360
20%
892
June16th to endNight
53%
360
16%
1440
18%
360
61%
360
26%
818
July1st to 15thNight
51%
340
13%
1360
17%
340
54%
340
19%
851
July16th to endNight
63%
396
15%
1437
16%
373
68%
373
27%
807
August1st to 15thNight
61%
569
17%
1639
12%
566
64%
566
30%
1043
August16th to endNight
58%
764
19%
1910
11%
764
59%
764
32%
1277
September1st to 15thNight
48%
720
23%
1800
11%
720
54%
720
32%
1186
September16th to endNight
53%
717
27%
1940
20%
717
59%
717
34%
1222
October1st to 15thNight
41%
720
20%
2160
15%
720
49%
720
27%
1360
October16th to endNight
32%
768
26%
2346
13%
768
49%
768
27%
1414
November1st to 15thNight
33%
760
21%
2472
12%
760
46%
760
24%
1504
November16th to endNight
27%
780
22%
2642
10%
780
42%
780
19%
1644
December1st to 15thNight
22%
780
15%
2730
6%
780
34%
780
14%
1849
December16th to endNight
19%
832
18%
2912
4%
832
36%
832
15%
1916

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
15%5%25%5%3445%7%39%
49266
Night
15%5%2442445%6%42%
48987
Cloud CoverDay
15%6%25%5%3445%7%39%
49275
Night
15%6%24424447%42%
48993
TransparencyDay
43%5%11%22%15%2
48955
Night
41%5%12%22%16%2
48816
SeeingDay
21%11%26%22%13%5%
6145
Night
19%12%29%26%10%
15656

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
14%7%27%6%3445%439%
1552
16th to endDay
13%7%46%5%3445%6%37%
1830
February1st to 15thDay
16%8%35%5%3445%7%35%
1710
16th to endDay
15%8%26%7%235%5%5%37%
1580
March1st to 15thDay
15%8%35%435%45%6%37%
1856
16th to endDay
18%6%34424346%40%
2190
April1st to 15thDay
18%5%25%43335%7%38%
2152
16th to endDay
15%325%42346%7%42%
2160
May1st to 15thDay
20%6%25%435%5%5%6%35%
2393
16th to endDay
17%6%245%445%6%8%35%
2618
June1st to 15thDay
14%5%245%35%6%6%9%34%
2520
16th to endDay
13%425%5%35%5%6%9%39%
2520
July1st to 15thDay
9%5%25%6%46%6%7%8%36%
2520
16th to endDay
9%426%5%36%6%6%10%38%
2632
August1st to 15thDay
13%435%6%35%6%5%8%36%
2298
16th to endDay
12%5%2443445%8%42%
2292
September1st to 15thDay
15%5%1443435%8%43%
2160
16th to endDay
14%424424446%46%
2017
October1st to 15thDay
17%5%1442445%6%42%
1800
16th to endDay
18%415%33435%6%43%
1878
November1st to 15thDay
16%7%34422346%44%
1716
16th to endDay
17%5%24323447%45%
1648
December1st to 15thDay
16%7%35%5%245%6%7%36%
1560
16th to endDay
18%8%36%424447%35%
1664
January1st to 15thNight
16%5%35%5%34447%39%
2716
16th to endNight
15%8%25%424346%42%
2744
February1st to 15thNight
15%8%35%5%34446%39%
2450
16th to endNight
15%5%344235%46%44%
1893
March1st to 15thNight
17%6%24424446%42%
2079
16th to endNight
18%6%24423335%44%
2032
April1st to 15thNight
16%5%24425%46%7%41%
1796
16th to endNight
17%42442335%6%45%
1800
May1st to 15thNight
18%7%245%2445%5%39%
1566
16th to endNight
14%5%25%5%245%47%41%
1495
June1st to 15thNight
17%5%2442435%7%42%
1440
16th to endNight
9%413435%5%7%10%43%
1440
July1st to 15thNight
10%5%246%35%5%6%8%39%
1440
16th to endNight
8%413435%6%7%11%43%
1534
August1st to 15thNight
10%5%15%4346%6%7%44%
1650
16th to endNight
12%5%25%43445%8%43%
1910
September1st to 15thNight
14%42342435%6%48%
1800
16th to endNight
11%424433346%49%
1940
October1st to 15thNight
16%6%24423346%45%
2160
16th to endNight
18%413212346%49%
2346
November1st to 15thNight
14%6%24423436%46%
2472
16th to endNight
16%5%2442445%6%41%
2642
December1st to 15thNight
18%6%35%5%36%5%5%6%34%
2730
16th to endNight
17%7%25%5%35%446%38%
2912

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 15thDay
14%7%26%6%34445%38%
1552
16th to endDay
13%8%46%43435%6%38%
1830
February1st to 15thDay
15%8%35%5%3445%7%36%
1710
16th to endDay
15%8%37%6%2436%5%37%
1580
March1st to 15thDay
15%7%26%43445%6%36%
1866
16th to endDay
19%7%24424346%40%
2189
April1st to 15thDay
18%6%35%42345%7%39%
2152
16th to endDay
15%425%5%2446%7%42%
2160
May1st to 15thDay
20%6%24435%5%5%6%35%
2393
16th to endDay
17%6%245%36%5%5%8%34%
2618
June1st to 15thDay
13%6%35%5%35%5%7%10%34%
2520
16th to endDay
12%5%245%35%5%7%9%38%
2520
July1st to 15thDay
9%5%15%6%47%6%7%8%36%
2520
16th to endDay
8%425%6%35%6%6%9%39%
2632
August1st to 15thDay
13%425%6%36%5%6%8%37%
2298
16th to endDay
13%425%43446%8%42%
2292
September1st to 15thDay
15%424335%35%7%44%
2160
16th to endDay
13%5%25%334446%45%
2017
October1st to 15thDay
17%6%1443345%6%43%
1800
16th to endDay
18%415%42335%6%43%
1878
November1st to 15thDay
17%7%23423346%44%
1716
16th to endDay
16%5%24323346%45%
1648
December1st to 15thDay
16%7%35%4245%6%7%36%
1560
16th to endDay
18%7%26%42445%8%34%
1664
January1st to 15thNight
16%5%35%5%34447%39%
2716
16th to endNight
16%8%34424446%42%
2744
February1st to 15thNight
15%8%25%5%3445%6%39%
2443
16th to endNight
16%5%344235%5%5%44%
1893
March1st to 15thNight
17%6%24424446%41%
2092
16th to endNight
18%6%24423345%44%
2032
April1st to 15thNight
16%5%3442445%7%41%
1796
16th to endNight
17%5%24423446%45%
1800
May1st to 15thNight
18%7%25%5%2345%5%39%
1566
16th to endNight
15%6%25%4245%48%41%
1495
June1st to 15thNight
17%4235%24447%42%
1440
16th to endNight
9%413435%47%10%43%
1440
July1st to 15thNight
11%5%345%5%5%5%6%8%39%
1440
16th to endNight
8%423425%7%8%10%43%
1534
August1st to 15thNight
10%4145%25%5%6%8%43%
1650
16th to endNight
12%5%25%5%345%5%9%42%
1910
September1st to 15thNight
14%4145%23346%48%
1800
16th to endNight
11%5%25%333347%49%
1940
October1st to 15thNight
16%6%25%423347%44%
2160
16th to endNight
17%5%23222346%50%
2346
November1st to 15thNight
15%6%24323446%46%
2472
16th to endNight
16%5%3442445%6%41%
2642
December1st to 15thNight
18%6%25%5%36%5%46%34%
2730
16th to endNight
16%7%35%434446%38%
2912

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
46%312%22%10%3
1553
16th to endDay
46%412%22%12%1
1830
February1st to 15thDay
46%5%12%22%11%2
1712
16th to endDay
47%410%25%10%1
1580
March1st to 15thDay
47%5%12%21%10%1
1866
16th to endDay
45%410%20%17%2
2190
April1st to 15thDay
44%49%23%13%4
2152
16th to endDay
39%5%10%19%20%4
2160
May1st to 15thDay
48%5%9%19%15%2
2393
16th to endDay
45%6%12%20%13%1
2622
June1st to 15thDay
43%8%14%22%10%
2520
16th to endDay
40%7%14%24%11%1
2520
July1st to 15thDay
42%7%12%21%14%2
2371
16th to endDay
38%8%12%25%13%2
2466
August1st to 15thDay
42%7%12%19%17%
2285
16th to endDay
37%6%10%23%19%2
2292
September1st to 15thDay
38%5%11%20%22%1
2160
16th to endDay
39%48%21%22%2
2017
October1st to 15thDay
40%5%12%21%17%1
1800
16th to endDay
40%410%26%16%1
1878
November1st to 15thDay
41%414%20%16%3
1716
16th to endDay
39%310%29%15%1
1648
December1st to 15thDay
45%5%16%20%10%1
1560
16th to endDay
48%415%20%11%
1664
January1st to 15thNight
44%412%21%14%3
2716
16th to endNight
43%411%25%13%1
2744
February1st to 15thNight
45%413%22%12%2
2452
16th to endNight
40%49%24%18%2
1893
March1st to 15thNight
43%412%22%14%2
2092
16th to endNight
41%411%21%17%3
2032
April1st to 15thNight
41%5%11%21%16%3
1796
16th to endNight
40%410%19%21%3
1800
May1st to 15thNight
46%5%11%17%17%1
1566
16th to endNight
41%7%14%16%16%3
1497
June1st to 15thNight
42%6%12%21%16%
1440
16th to endNight
33%7%13%29%14%
1440
July1st to 15thNight
42%7%13%20%13%2
1360
16th to endNight
31%9%18%23%14%2
1437
August1st to 15thNight
35%8%14%20%18%2
1639
16th to endNight
38%6%11%19%21%2
1910
September1st to 15thNight
36%6%10%20%23%1
1800
16th to endNight
36%47%22%26%2
1940
October1st to 15thNight
40%312%24%15%2
2160
16th to endNight
36%410%30%17%1
2346
November1st to 15thNight
39%412%22%16%5%
2472
16th to endNight
42%410%25%14%1
2642
December1st to 15thNight
49%5%14%18%10%1
2730
16th to endNight
46%5%12%22%11%1
2912

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%25%23%11%31
90
16th to endDay
26%20%35%16%
134
February1st to 15thDay
28%34%28%8%
146
16th to endDay
23%20%35%16%3
239
March1st to 15thDay
28%17%27%21%5%
270
16th to endDay
23%19%32%15%6%2
288
April1st to 15thDay
23%16%31%17%10%2
270
16th to endDay
21%11%32%21%7%6%
270
May1st to 15thDay
37%11%21%14%10%3
288
16th to endDay
22%7%25%23%17%4
331
June1st to 15thDay
18%9%25%23%18%4
315
16th to endDay
18%8%29%25%13%4
315
July1st to 15thDay
12%327%30%19%5%
305
16th to endDay
14%321%31%22%7%
326
August1st to 15thDay
18%317%29%20%10%
313
16th to endDay
12%218%30%19%15%
332
September1st to 15thDay
17%8%23%20%20%9%
315
16th to endDay
17%6%18%23%18%15%
314
October1st to 15thDay
24%5%20%26%16%6%
315
16th to endDay
20%13%31%20%12%1
325
November1st to 15thDay
21%11%30%22%11%2
280
16th to endDay
20%24%28%20%5%
178
December1st to 15thDay
37%18%24%6%11%1
90
16th to endDay
35%25%32%6%1
96
January1st to 15thNight
20%19%35%20%3
780
16th to endNight
22%18%37%19%2
832
February1st to 15thNight
21%19%37%20%1
760
16th to endNight
20%22%36%17%2
631
March1st to 15thNight
24%19%30%22%3
720
16th to endNight
20%16%36%19%6%
768
April1st to 15thNight
19%18%37%20%4
718
16th to endNight
20%9%34%26%8%
720
May1st to 15thNight
23%8%32%26%9%
486
16th to endNight
18%6%22%37%14%1
375
June1st to 15thNight
20%425%33%15%
360
16th to endNight
10%225%48%12%
360
July1st to 15thNight
12%421%41%20%
340
16th to endNight
8%220%41%23%3
396
August1st to 15thNight
15%114%43%23%2
569
16th to endNight
14%213%39%27%2
764
September1st to 15thNight
16%5%23%34%19%1
720
16th to endNight
14%420%29%25%4
717
October1st to 15thNight
19%7%24%28%17%2
720
16th to endNight
22%13%29%25%9%
768
November1st to 15thNight
19%9%31%26%11%
760
16th to endNight
19%16%31%22%8%
780
December1st to 15thNight
24%15%31%21%6%
780
16th to endNight
22%18%35%21%2
832
Page generated at 2018-02-15 10:58:43. Version ac04

Copyright 2018 A. Danko


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