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 2017-03-22.

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
68%
14969
28%
45292
25%
14933
71%
14933
42%
24045

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%
732
20%
1983
16%
732
59%
732
33%
1245
April1st to 15thNight
49%
659
22%
1649
13%
659
52%
659
33%
1066
April16th to endNight
58%
660
24%
1650
12%
660
61%
660
48%
931
May1st to 15thNight
65%
618
26%
1608
16%
618
68%
618
53%
849
May16th to endNight
65%
376
25%
1403
22%
376
71%
376
42%
635
June1st to 15thNight
69%
330
29%
1320
30%
330
76%
330
48%
526
June16th to endNight
86%
330
36%
1320
43%
330
91%
330
77%
396
July1st to 15thNight
90%
373
35%
1303
37%
373
92%
373
80%
431
July16th to endNight
92%
522
35%
1467
32%
489
92%
489
77%
578
August1st to 15thNight
90%
545
39%
1528
29%
542
91%
542
82%
609
August16th to endNight
91%
700
39%
1750
25%
700
91%
700
83%
777
September1st to 15thNight
90%
660
43%
1650
32%
660
91%
660
80%
750
September16th to endNight
81%
656
41%
1788
38%
656
83%
656
70%
799
October1st to 15thNight
74%
660
30%
1980
32%
660
77%
660
46%
1012
October16th to endNight
74%
704
34%
2112
37%
704
77%
704
48%
1061
November1st to 15thNight
69%
700
31%
2175
32%
700
72%
700
44%
1128
November16th to endNight
68%
720
26%
2373
28%
720
70%
720
36%
1276
December1st to 15thNight
59%
720
23%
2520
24%
720
63%
720
26%
1518
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%423323346%59%
45589
Night
6%423323447%55%
45483
TransparencyDay
24%39%18%24%20%
45279
Night
25%410%17%22%20%
45293
SeeingDay
9%9%28%35%14%3
5356
Night
8%313%29%33%11%
14979

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
12%7%36%426%35%6%40%
2037
April1st to 15thDay
12%8%5%432445%6%41%
1969
16th to endDay
7%5%23423346%56%
1980
May1st to 15thDay
332221335%9%60%
2009
16th to endDay
6%42431345%8%55%
2354
June1st to 15thDay
3312223248%63%
2310
16th to endDay
11111135%81%
2310
July1st to 15thDay
1112245%79%
2239
16th to endDay
1111335%79%
2286
August1st to 15thDay
1111235%80%
2093
16th to endDay
112235%81%
2100
September1st to 15thDay
111222482%
1980
16th to endDay
222212335%72%
1840
October1st to 15thDay
441332236%6%61%
1650
16th to endDay
5%213323446%61%
1760
November1st to 15thDay
10%424423246%54%
1684
16th to endDay
9%5%24424446%50%
1584
December1st to 15thDay
12%8%25%5%25%5%5%5%39%
1440
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%7%34425%5%5%8%43%
1983
April1st to 15thNight
11%6%25%5%35%45%7%42%
1649
16th to endNight
5%424413448%56%
1650
May1st to 15thNight
14143235%5%8%59%
1608
16th to endNight
35%2333445%7%56%
1402
June1st to 15thNight
131322445%8%62%
1320
16th to endNight
112137%79%
1320
July1st to 15thNight
111335%8%74%
1389
16th to endNight
1111245%9%69%
1575
August1st to 15thNight
1121335%8%71%
1537
16th to endNight
111348%76%
1750
September1st to 15thNight
11121222480%
1650
16th to endNight
2112112336%72%
1788
October1st to 15thNight
4412324446%60%
1980
16th to endNight
5%213324347%60%
2112
November1st to 15thNight
7%423323447%56%
2175
16th to endNight
7%5%2332445%7%52%
2373
December1st to 15thNight
10%7%245%3445%6%43%
2520
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
41%6%12%18%17%4
2037
April1st to 15thDay
40%312%22%17%3
1969
16th to endDay
24%6%13%26%22%6%
1980
May1st to 15thDay
17%412%24%30%10%
2009
16th to endDay
20%6%15%23%24%8%
2358
June1st to 15thDay
15%5%12%21%23%21%
2310
16th to endDay
6%15%14%32%39%
2310
July1st to 15thDay
5%15%10%25%51%
2096
16th to endDay
7%26%11%27%44%
2131
August1st to 15thDay
6%15%13%27%45%
2077
16th to endDay
5%1313%35%40%
2100
September1st to 15thDay
7%2410%30%44%
1980
16th to endDay
11%25%22%33%25%
1840
October1st to 15thDay
21%49%19%28%17%
1650
16th to endDay
21%39%21%25%18%
1760
November1st to 15thDay
30%310%18%26%10%
1684
16th to endDay
33%39%17%27%8%
1584
December1st to 15thDay
43%410%14%18%9%
1440
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
33%8%15%16%18%8%
1983
April1st to 15thNight
36%414%22%15%6%
1649
16th to endNight
22%5%16%23%23%8%
1650
May1st to 15thNight
18%5%12%21%26%15%
1609
16th to endNight
17%7%14%23%27%9%
1403
June1st to 15thNight
14%5%15%20%18%26%
1320
16th to endNight
427%11%25%48%
1320
July1st to 15thNight
427%11%20%53%
1303
16th to endNight
6%29%14%24%42%
1467
August1st to 15thNight
5%17%16%23%45%
1528
16th to endNight
426%13%28%43%
1750
September1st to 15thNight
7%16%9%23%51%
1650
16th to endNight
10%26%19%30%30%
1788
October1st to 15thNight
22%47%20%25%19%
1980
16th to endNight
20%47%19%26%19%
2112
November1st to 15thNight
25%312%19%27%12%
2175
16th to endNight
27%6%10%17%25%12%
2373
December1st to 15thNight
38%5%9%15%20%11%
2520
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
12%12%41%22%9%1
250
April1st to 15thDay
22%19%32%21%4
209
16th to endDay
13%17%37%26%4
210
May1st to 15thDay
8%13%39%31%41
228
16th to endDay
8%15%27%37%6%4
266
June1st to 15thDay
5%8%42%31%9%2
255
16th to endDay
432%42%14%4
255
July1st to 15thDay
23%55%12%6%
245
16th to endDay
117%53%18%8%
271
August1st to 15thDay
1225%49%15%5%
255
16th to endDay
118%57%16%5%
268
September1st to 15thDay
321%48%18%6%
255
16th to endDay
47%18%43%20%5%
255
October1st to 15thDay
5%7%30%36%15%4
255
16th to endDay
8%7%31%30%20%1
272
November1st to 15thDay
10%8%16%26%30%7%
190
16th to endDay
10%10%27%30%17%2
84
December1st to 15thDay
21%8%35%26%8%
60
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%421%31%25%5%
732
April1st to 15thNight
11%9%21%29%23%4
659
16th to endNight
5%7%23%26%25%10%
660
May1st to 15thNight
1321%36%27%9%
619
16th to endNight
4321%30%32%7%
377
June1st to 15thNight
2320%36%32%5%
330
16th to endNight
19%35%44%8%
330
July1st to 15thNight
15%24%50%17%
373
16th to endNight
115%55%27%
522
August1st to 15thNight
427%48%17%
545
16th to endNight
5%24%53%15%
700
September1st to 15thNight
15%24%50%18%
660
16th to endNight
410%21%44%18%
656
October1st to 15thNight
5%310%30%33%16%
660
16th to endNight
6%210%28%32%19%
704
November1st to 15thNight
8%212%30%32%12%
700
16th to endNight
8%312%32%31%11%
720
December1st to 15thNight
11%416%33%27%7%
720
16th to endNight
17%7%17%28%22%5%
768
Page generated at 2017-03-23 04:36:17. Version ac04

Copyright 2017 A. Danko


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