Tularcitos Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tularcitos Observatory clear sky chart from 2005-11-05 to 2017-12-04.

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
68%
15848
28%
47881
26%
15812
71%
15812
43%
25280

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
59%
716
20%
2360
19%
716
62%
716
30%
1371
January16th to endNight
58%
768
24%
2496
26%
768
60%
768
27%
1533
February1st to 15thNight
58%
700
23%
2258
24%
700
62%
700
27%
1371
February16th to endNight
52%
632
20%
1895
19%
632
55%
632
26%
1224
March1st to 15thNight
55%
720
18%
2016
18%
720
57%
720
28%
1294
March16th to endNight
55%
768
21%
2079
16%
768
58%
768
33%
1303
April1st to 15thNight
50%
719
22%
1799
13%
719
53%
719
33%
1160
April16th to endNight
57%
720
25%
1800
13%
720
61%
720
46%
1030
May1st to 15thNight
65%
674
25%
1754
16%
674
67%
674
53%
927
May16th to endNight
66%
411
27%
1534
24%
411
71%
411
41%
704
June1st to 15thNight
68%
360
28%
1440
29%
360
75%
360
48%
581
June16th to endNight
87%
360
39%
1440
47%
360
92%
360
78%
426
July1st to 15thNight
91%
409
33%
1429
35%
409
93%
409
81%
469
July16th to endNight
92%
564
37%
1593
34%
531
93%
531
78%
621
August1st to 15thNight
89%
595
37%
1668
27%
592
90%
592
80%
674
August16th to endNight
91%
764
42%
1910
27%
764
92%
764
84%
845
September1st to 15thNight
90%
720
41%
1800
31%
720
91%
720
77%
836
September16th to endNight
81%
716
43%
1950
40%
716
84%
716
70%
865
October1st to 15thNight
76%
720
30%
2160
32%
720
79%
720
49%
1073
October16th to endNight
76%
768
36%
2304
40%
768
78%
768
49%
1144
November1st to 15thNight
70%
760
29%
2361
31%
760
73%
760
44%
1220
November16th to endNight
68%
780
26%
2571
29%
780
70%
780
35%
1398
December1st to 15thNight
59%
736
22%
2576
23%
736
64%
736
26%
1546
December16th to endNight
50%
768
21%
2688
21%
768
55%
768
22%
1665

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
6%413323346%60%
48605
Night
6%423323447%55%
48072
TransparencyDay
23%39%17%24%21%
48295
Night
24%410%17%22%20%
47882
SeeingDay
8%8%27%34%16%4
6343
Night
7%313%29%33%11%
15858

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
10%6%26%425%347%45%
1575
16th to endDay
13%9%25%423345%44%
1728
February1st to 15thDay
12%9%25%425%345%43%
1605
16th to endDay
15%8%35%5%35%44437%
1579
March1st to 15thDay
11%7%25%5%35%5%6%8%36%
1941
16th to endDay
11%7%36%426%45%6%40%
2145
April1st to 15thDay
11%8%5%442445%6%41%
2149
16th to endDay
7%5%24423346%55%
2160
May1st to 15thDay
332231335%9%60%
2193
16th to endDay
6%42431345%8%56%
2575
June1st to 15thDay
3312323347%63%
2520
16th to endDay
1111113482%
2520
July1st to 15thDay
112245%80%
2442
16th to endDay
1111235%80%
2468
August1st to 15thDay
1111235%79%
2283
16th to endDay
112235%82%
2292
September1st to 15thDay
111222481%
2160
16th to endDay
222212335%72%
2006
October1st to 15thDay
441331235%6%63%
1800
16th to endDay
4213323446%61%
1920
November1st to 15thDay
9%424423346%53%
1827
16th to endDay
8%5%24424447%50%
1716
December1st to 15thDay
12%8%25%5%25%5%6%5%39%
1465
16th to endDay
14%8%35%33435%6%40%
1536
January1st to 15thNight
9%7%35%5%3345%7%45%
2360
16th to endNight
12%6%35%434446%44%
2496
February1st to 15thNight
11%6%35%5%35%45%8%40%
2247
16th to endNight
13%7%25%5%35%447%40%
1895
March1st to 15thNight
9%7%35%5%25%5%5%7%42%
2016
16th to endNight
9%6%35%5%25%5%5%8%43%
2079
April1st to 15thNight
10%6%25%5%3445%7%42%
1799
16th to endNight
5%42441345%8%56%
1800
May1st to 15thNight
14143235%5%7%58%
1754
16th to endNight
35%2333445%7%55%
1533
June1st to 15thNight
1313324447%61%
1440
16th to endNight
111126%80%
1440
July1st to 15thNight
113347%75%
1515
16th to endNight
1111235%9%71%
1701
August1st to 15thNight
1121335%8%71%
1677
16th to endNight
111348%77%
1910
September1st to 15thNight
11121222478%
1800
16th to endNight
212112336%73%
1950
October1st to 15thNight
4412324346%63%
2160
16th to endNight
4213324347%61%
2304
November1st to 15thNight
7%423323448%55%
2361
16th to endNight
7%5%2342445%7%51%
2571
December1st to 15thNight
10%6%245%3445%6%43%
2576
16th to endNight
15%7%34424446%41%
2688

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
37%48%20%18%10%
1575
16th to endDay
40%5%7%12%20%13%
1728
February1st to 15thDay
40%47%17%22%7%
1605
16th to endDay
46%6%7%20%13%4
1579
March1st to 15thDay
40%5%12%18%14%7%
1941
16th to endDay
40%6%13%18%17%4
2145
April1st to 15thDay
40%312%23%17%3
2149
16th to endDay
25%6%12%25%22%7%
2160
May1st to 15thDay
17%412%25%30%9%
2193
16th to endDay
20%7%14%23%25%8%
2579
June1st to 15thDay
16%5%11%21%24%20%
2520
16th to endDay
5%15%14%31%41%
2520
July1st to 15thDay
5%15%9%23%54%
2299
16th to endDay
6%26%10%25%48%
2313
August1st to 15thDay
6%15%13%26%46%
2267
16th to endDay
5%1313%34%41%
2292
September1st to 15thDay
7%25%12%30%41%
2160
16th to endDay
11%25%22%34%23%
2006
October1st to 15thDay
19%38%18%27%22%
1800
16th to endDay
21%310%21%23%20%
1920
November1st to 15thDay
30%311%19%24%10%
1827
16th to endDay
32%39%17%27%8%
1716
December1st to 15thDay
43%49%14%19%8%
1465
16th to endDay
44%411%16%15%7%
1536
January1st to 15thNight
35%410%18%20%10%
2360
16th to endNight
39%5%9%11%16%18%
2496
February1st to 15thNight
38%5%9%17%19%9%
2258
16th to endNight
40%6%11%20%15%5%
1895
March1st to 15thNight
38%6%12%16%16%10%
2016
16th to endNight
32%7%15%17%17%8%
2079
April1st to 15thNight
37%413%23%15%5%
1799
16th to endNight
23%5%15%22%23%9%
1800
May1st to 15thNight
18%5%12%21%27%14%
1755
16th to endNight
18%8%14%21%27%9%
1534
June1st to 15thNight
15%5%14%20%18%26%
1440
16th to endNight
417%11%25%49%
1440
July1st to 15thNight
317%10%19%56%
1429
16th to endNight
6%19%13%23%46%
1593
August1st to 15thNight
6%17%15%22%46%
1668
16th to endNight
426%13%28%44%
1910
September1st to 15thNight
7%26%11%23%48%
1800
16th to endNight
10%26%19%32%29%
1950
October1st to 15thNight
20%36%19%24%24%
2160
16th to endNight
20%47%18%26%22%
2304
November1st to 15thNight
24%313%19%26%11%
2361
16th to endNight
28%6%10%17%25%11%
2571
December1st to 15thNight
38%5%9%15%20%11%
2576
16th to endNight
41%5%11%17%15%8%
2688

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
19%9%28%22%18%1
204
16th to endDay
15%11%28%26%15%3
256
February1st to 15thDay
14%15%24%22%19%2
241
16th to endDay
21%13%27%25%10%1
238
March1st to 15thDay
15%14%30%22%12%3
270
16th to endDay
13%13%41%20%9%1
288
April1st to 15thDay
20%18%31%21%7%
269
16th to endDay
12%17%37%25%5%1
270
May1st to 15thDay
8%13%37%29%7%2
288
16th to endDay
7%14%26%35%10%5%
330
June1st to 15thDay
5%9%39%30%11%3
315
16th to endDay
326%44%18%5%
315
July1st to 15thDay
19%52%17%8%
305
16th to endDay
117%50%21%9%
327
August1st to 15thDay
2221%48%20%5%
315
16th to endDay
117%52%21%7%
332
September1st to 15thDay
1321%46%20%6%
315
16th to endDay
46%19%44%20%5%
315
October1st to 15thDay
47%29%36%18%3
315
16th to endDay
7%7%27%27%25%5%
336
November1st to 15thDay
9%6%19%30%28%5%
243
16th to endDay
9%9%23%30%23%3
126
December1st to 15thDay
19%10%33%27%9%
66
16th to endDay
18%9%12%37%15%6%
64
January1st to 15thNight
11%315%29%30%10%
720
16th to endNight
14%314%30%28%9%
768
February1st to 15thNight
14%413%31%26%8%
704
16th to endNight
17%5%18%31%21%6%
632
March1st to 15thNight
12%6%16%30%26%8%
720
16th to endNight
10%5%22%31%26%5%
768
April1st to 15thNight
11%9%21%30%23%4
719
16th to endNight
5%7%23%27%25%10%
720
May1st to 15thNight
1321%36%27%8%
675
16th to endNight
5%320%30%32%8%
412
June1st to 15thNight
2320%35%33%5%
360
16th to endNight
18%33%46%9%
360
July1st to 15thNight
423%51%19%
409
16th to endNight
115%55%27%
564
August1st to 15thNight
426%50%17%
595
16th to endNight
423%52%17%
764
September1st to 15thNight
1426%50%17%
720
16th to endNight
319%23%44%17%
716
October1st to 15thNight
5%39%32%33%15%
720
16th to endNight
5%210%27%33%20%
768
November1st to 15thNight
8%212%33%31%12%
760
16th to endNight
8%312%32%32%10%
780
December1st to 15thNight
11%416%33%27%7%
736
16th to endNight
17%7%17%28%22%5%
768
Page generated at 2017-12-05 07:18:57. Version ac04

Copyright 2017 A. Danko


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