Longhorn Cavern State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Longhorn Cavern State Park clear sky chart from 2005-11-05 to 2017-08-12.

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
53%
15344
27%
46556
19%
15299
61%
15299
37%
26172

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
41%
897
27%
2327
13%
895
49%
895
37%
1426
January16th to endNight
39%
888
31%
2424
13%
888
51%
888
36%
1454
February1st to 15thNight
37%
704
29%
2106
13%
698
50%
698
34%
1188
February16th to endNight
27%
632
30%
1894
9%
632
45%
632
35%
1068
March1st to 15thNight
37%
570
28%
2010
16%
570
51%
570
28%
1148
March16th to endNight
35%
576
26%
2112
17%
576
49%
576
30%
1155
April1st to 15thNight
31%
539
25%
1977
14%
539
48%
539
29%
1080
April16th to endNight
32%
540
26%
1738
14%
540
49%
540
30%
1025
May1st to 15thNight
35%
539
23%
1620
15%
539
48%
539
33%
968
May16th to endNight
50%
562
25%
1684
20%
561
60%
561
35%
987
June1st to 15thNight
72%
540
22%
1620
23%
540
77%
540
51%
799
June16th to endNight
73%
540
24%
1620
28%
540
75%
540
40%
902
July1st to 15thNight
80%
510
23%
1530
26%
510
82%
510
46%
804
July16th to endNight
85%
564
28%
1594
32%
531
88%
531
50%
798
August1st to 15thNight
91%
527
32%
1628
38%
524
91%
524
57%
741
August16th to endNight
81%
525
21%
1794
27%
525
81%
525
33%
1017
September1st to 15thNight
77%
495
21%
1815
26%
495
78%
495
31%
1030
September16th to endNight
74%
492
27%
1815
28%
492
76%
492
31%
995
October1st to 15thNight
71%
498
35%
1818
33%
498
75%
498
40%
894
October16th to endNight
59%
704
35%
2112
22%
704
67%
704
47%
1073
November1st to 15thNight
54%
742
30%
2142
19%
742
60%
742
40%
1199
November16th to endNight
49%
900
31%
2340
16%
900
57%
900
40%
1377
December1st to 15thNight
44%
900
29%
2340
16%
900
50%
900
34%
1465
December16th to endNight
40%
960
25%
2496
11%
960
48%
960
33%
1579

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
11%424424447%49%
47406
Night
9%413323347%55%
46758
Cloud CoverDay
11%424424446%49%
47404
Night
10%423323347%55%
46758
TransparencyDay
34%5%10%19%20%9%
47104
Night
29%5%11%20%20%12%
46563
SeeingDay
11%418%31%26%7%
5298
Night
11%5%25%37%17%1
15349

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
15%423313335%53%
1611
16th to endDay
14%413322335%54%
1809
February1st to 15thDay
13%5%23312236%55%
1750
16th to endDay
16%413313345%53%
1580
March1st to 15thDay
17%6%23313345%47%
1949
16th to endDay
14%6%3331333451%
2112
April1st to 15thDay
11%6%24423346%48%
1971
16th to endDay
12%6%24424336%48%
2217
May1st to 15thDay
15%5%26%43445%7%39%
2331
16th to endDay
14%6%26%5%35%5%6%6%38%
2430
June1st to 15thDay
43135%345%6%8%53%
2340
16th to endDay
9%425%435%5%6%9%42%
2340
July1st to 15thDay
6%3246%46%5%6%9%44%
2340
16th to endDay
6%3134345%6%11%50%
2466
August1st to 15thDay
2112325%45%8%61%
2232
16th to endDay
5%425%6%46%5%7%11%39%
2056
September1st to 15thDay
9%5%36%6%345%5%7%41%
1815
16th to endDay
8%3246%35%5%5%6%48%
1815
October1st to 15thDay
9%413423336%55%
1801
16th to endDay
8%31221222467%
1760
November1st to 15thDay
10%6%14423335%52%
1713
16th to endDay
12%5%2331332457%
1620
December1st to 15thDay
15%7%23322345%49%
1620
16th to endDay
14%6%23323335%49%
1728
January1st to 15thNight
14%423313236%54%
2327
16th to endNight
15%312323245%54%
2424
February1st to 15thNight
12%5%2321223458%
2102
16th to endNight
12%31342333456%
1894
March1st to 15thNight
13%5%24323348%49%
2010
16th to endNight
10%423323446%54%
2112
April1st to 15thNight
9%424423346%53%
1977
16th to endNight
11%42432345%7%50%
1738
May1st to 15thNight
10%5%2432345%9%49%
1619
16th to endNight
8%4244235%5%9%49%
1683
June1st to 15thNight
221221345%7%65%
1620
16th to endNight
4212325%5%6%8%56%
1620
July1st to 15thNight
42133144411%57%
1620
16th to endNight
311221345%12%60%
1702
August1st to 15thNight
212213348%69%
1638
16th to endNight
4315%4345%7%9%50%
1794
September1st to 15thNight
8%3134345%6%8%49%
1815
16th to endNight
6%4144345%5%7%51%
1815
October1st to 15thNight
7%312322336%62%
1818
16th to endNight
8%31321324465%
2112
November1st to 15thNight
9%413222336%60%
2142
16th to endNight
11%423212335%59%
2340
December1st to 15thNight
14%6%23313345%51%
2340
16th to endNight
13%6%2432333452%
2496

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
15%5%14213335%53%
1611
16th to endDay
14%41331334454%
1809
February1st to 15thDay
14%5%13212235%56%
1750
16th to endDay
16%41331334453%
1580
March1st to 15thDay
17%6%23322346%46%
1949
16th to endDay
15%5%23322335%51%
2110
April1st to 15thDay
12%6%2433335%6%48%
1971
16th to endDay
12%6%24424435%48%
2217
May1st to 15thDay
15%6%35%43445%7%39%
2331
16th to endDay
14%6%26%5%35%5%6%6%38%
2430
June1st to 15thDay
43135%345%6%8%52%
2340
16th to endDay
10%4245%35%5%6%9%42%
2340
July1st to 15thDay
7%3246%36%5%7%8%44%
2340
16th to endDay
6%2144245%6%10%49%
2466
August1st to 15thDay
211232445%9%61%
2232
16th to endDay
6%325%6%46%6%6%11%40%
2056
September1st to 15thDay
9%5%26%7%445%5%7%42%
1815
16th to endDay
8%425%6%25%5%5%6%48%
1815
October1st to 15thDay
9%423414335%55%
1801
16th to endDay
8%312212225%67%
1760
November1st to 15thDay
11%5%25%323336%52%
1713
16th to endDay
12%5%1431232457%
1620
December1st to 15thDay
16%6%23412335%49%
1620
16th to endDay
14%7%24323345%48%
1728
January1st to 15thNight
14%423313335%54%
2327
16th to endNight
15%313223245%54%
2424
February1st to 15thNight
12%5%2331223458%
2102
16th to endNight
13%32332333456%
1894
March1st to 15thNight
13%5%24323347%49%
2010
16th to endNight
11%32331345%5%54%
2112
April1st to 15thNight
9%5%24423346%53%
1977
16th to endNight
12%43432345%6%50%
1738
May1st to 15thNight
11%423323449%49%
1619
16th to endNight
8%32442346%9%49%
1683
June1st to 15thNight
231222236%7%65%
1620
16th to endNight
5%213325%5%5%9%56%
1620
July1st to 15thNight
5%2123234311%58%
1620
16th to endNight
311121346%12%60%
1702
August1st to 15thNight
211213348%69%
1638
16th to endNight
43144345%7%9%50%
1794
September1st to 15thNight
9%3234345%6%9%49%
1815
16th to endNight
6%5%1442345%7%51%
1815
October1st to 15thNight
7%313322335%62%
1818
16th to endNight
8%31221323465%
2112
November1st to 15thNight
9%323312336%60%
2142
16th to endNight
11%423212235%59%
2340
December1st to 15thNight
15%5%24313246%51%
2340
16th to endNight
14%5%24322335%52%
2496

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
34%26%18%24%12%
1612
16th to endDay
32%36%13%26%17%
1809
February1st to 15thDay
32%36%15%22%19%
1751
16th to endDay
34%35%19%22%14%
1580
March1st to 15thDay
39%47%12%20%14%
1949
16th to endDay
37%38%16%22%10%
2112
April1st to 15thDay
36%5%8%16%18%14%
1971
16th to endDay
39%46%18%19%11%
2217
May1st to 15thDay
43%6%9%13%18%8%
2331
16th to endDay
45%6%10%17%17%3
2434
June1st to 15thDay
28%7%11%23%23%6%
2340
16th to endDay
37%8%12%20%16%4
2340
July1st to 15thDay
33%8%15%25%14%2
2201
16th to endDay
25%8%19%29%14%1
2311
August1st to 15thDay
19%6%16%35%20%2
2218
16th to endDay
36%9%17%23%11%2
2056
September1st to 15thDay
40%7%11%20%15%5%
1815
16th to endDay
33%7%10%18%20%9%
1815
October1st to 15thDay
31%39%20%19%15%
1801
16th to endDay
22%2417%31%21%
1760
November1st to 15thDay
35%47%21%19%11%
1713
16th to endDay
32%36%13%22%23%
1620
December1st to 15thDay
39%46%17%22%9%
1620
16th to endDay
37%48%15%22%10%
1728
January1st to 15thNight
33%26%17%21%18%
2327
16th to endNight
32%35%14%24%19%
2424
February1st to 15thNight
31%36%13%23%21%
2112
16th to endNight
32%26%16%23%18%
1894
March1st to 15thNight
34%48%12%24%14%
2010
16th to endNight
30%5%9%17%23%11%
2112
April1st to 15thNight
33%49%17%19%16%
1977
16th to endNight
35%5%10%17%19%12%
1738
May1st to 15thNight
32%6%12%21%18%9%
1620
16th to endNight
30%7%14%27%16%3
1685
June1st to 15thNight
17%5%16%27%26%5%
1620
16th to endNight
24%8%14%28%19%4
1620
July1st to 15thNight
20%7%22%32%16%1
1530
16th to endNight
16%8%24%34%15%1
1594
August1st to 15thNight
13%5%19%38%20%2
1628
16th to endNight
28%9%20%26%11%3
1794
September1st to 15thNight
30%8%16%24%15%5%
1815
16th to endNight
30%6%12%20%18%10%
1815
October1st to 15thNight
24%411%24%20%15%
1818
16th to endNight
23%26%16%27%23%
2112
November1st to 15thNight
28%47%21%23%14%
2142
16th to endNight
29%37%14%21%23%
2340
December1st to 15thNight
35%39%17%22%12%
2340
16th to endNight
37%36%14%23%14%
2496

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
17%7%27%37%7%1
90
16th to endDay
10%15%37%26%10%
96
February1st to 15thDay
8%11%33%37%7%1
90
16th to endDay
16%9%40%29%3
81
March1st to 15thDay
21%12%34%23%8%
90
16th to endDay
8%5%41%36%8%
96
April1st to 15thDay
13%8%34%37%5%
90
16th to endDay
13%11%41%22%11%
327
May1st to 15thDay
16%8%36%27%9%
468
16th to endDay
19%5%27%31%13%2
517
June1st to 15thDay
6%112%46%27%5%
495
16th to endDay
8%19%40%30%8%
495
July1st to 15thDay
5%17%37%38%9%
475
16th to endDay
4326%48%16%
515
August1st to 15thDay
21226%50%16%
417
16th to endDay
10%5%35%34%12%
224
September1st to 15thDay
41415%48%25%
90
16th to endDay
11%314%43%27%
90
October1st to 15thDay
211%27%44%14%
90
16th to endDay
19%311%29%35%1
96
November1st to 15thDay
22%5%27%31%6%6%
90
16th to endDay
26%8%26%22%13%2
90
December1st to 15thDay
26%317%25%16%10%
90
16th to endDay
26%12%34%20%5%1
96
January1st to 15thNight
16%8%29%35%9%
900
16th to endNight
16%6%34%34%7%
888
February1st to 15thNight
15%10%33%33%6%
704
16th to endNight
16%7%47%25%2
632
March1st to 15thNight
16%7%34%35%5%
570
16th to endNight
12%8%40%33%4
576
April1st to 15thNight
11%6%46%32%2
539
16th to endNight
12%7%45%26%7%
540
May1st to 15thNight
11%6%43%31%6%
540
16th to endNight
10%232%38%15%1
563
June1st to 15thNight
3118%50%26%
540
16th to endNight
4114%53%24%2
540
July1st to 15thNight
5%17%49%33%2
510
16th to endNight
35%46%39%4
564
August1st to 15thNight
2239%50%4
527
16th to endNight
6%342%41%5%
525
September1st to 15thNight
10%5%37%41%5%
495
16th to endNight
8%16%37%43%3
492
October1st to 15thNight
9%213%44%26%4
498
16th to endNight
10%323%36%23%1
704
November1st to 15thNight
10%426%38%19%1
742
16th to endNight
15%6%25%36%15%1
900
December1st to 15thNight
18%7%26%37%9%
900
16th to endNight
18%7%28%36%8%
960
Page generated at 2017-08-13 13:16:15. Version ac04

Copyright 2017 A. Danko


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