Barton Warnock Visitor Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barton Warnock Visitor Center clear sky chart from 2005-11-06 to 2024-01-12.

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
68%
23532
22%
74477
17%
23484
73%
23484
23%
48888

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 10thNight
66%
756
27%
2268
18%
756
74%
756
25%
1468
January11th to 20thNight
67%
728
23%
2184
16%
728
73%
728
22%
1504
January21st to endNight
59%
792
25%
2376
17%
792
67%
792
21%
1642
February1st to 10thNight
61%
720
25%
2160
16%
720
70%
720
26%
1407
February11th to 20thNight
62%
703
19%
2098
11%
700
68%
700
21%
1430
February21st to endNight
54%
592
26%
1776
14%
592
64%
592
26%
1132
March1st to 10thNight
53%
720
24%
2160
13%
720
63%
720
25%
1411
March11th to 20thNight
55%
720
23%
2052
13%
720
62%
720
24%
1399
March21st to endNight
52%
605
28%
1991
16%
605
65%
605
24%
1234
April1st to 10thNight
54%
540
26%
1800
17%
540
66%
540
22%
1163
April11th to 20thNight
48%
533
27%
1777
15%
533
64%
533
25%
1081
April21st to endNight
51%
540
26%
1800
19%
540
63%
540
24%
1117
May1st to 10thNight
58%
540
20%
1800
17%
540
67%
540
23%
1162
May11th to 20thNight
57%
531
19%
1770
18%
531
63%
531
18%
1223
May21st to endNight
62%
582
19%
1867
19%
582
67%
582
21%
1265
June1st to 10thNight
72%
540
19%
1620
18%
540
77%
540
25%
1064
June11th to 20thNight
73%
540
19%
1620
18%
540
76%
540
23%
1104
June21st to endNight
77%
540
18%
1727
20%
540
80%
540
20%
1180
July1st to 10thNight
74%
525
13%
1750
14%
525
76%
525
16%
1284
July11th to 20thNight
86%
522
21%
1740
25%
522
87%
522
23%
1138
July21st to endNight
82%
591
15%
1859
18%
558
83%
558
16%
1343
August1st to 10thNight
86%
537
19%
1779
23%
534
87%
534
21%
1168
August11th to 20thNight
82%
534
20%
1778
23%
534
83%
534
20%
1212
August21st to endNight
81%
594
14%
1980
16%
594
82%
594
17%
1423
September1st to 10thNight
79%
540
15%
1800
16%
540
80%
540
17%
1280
September11th to 20thNight
74%
540
16%
1921
17%
540
74%
540
14%
1393
September21st to endNight
76%
540
21%
1980
23%
540
77%
540
19%
1303
October1st to 10thNight
79%
540
26%
1980
27%
540
82%
540
23%
1228
October11th to 20thNight
73%
610
28%
2050
25%
610
76%
610
21%
1335
October21st to endNight
73%
792
25%
2376
18%
792
76%
792
27%
1493
November1st to 10thNight
78%
740
27%
2220
20%
740
80%
740
30%
1376
November11th to 20thNight
74%
945
24%
2465
15%
945
77%
945
30%
1638
November21st to endNight
64%
950
23%
2470
12%
950
69%
950
27%
1707
December1st to 10thNight
71%
950
25%
2470
17%
950
74%
950
27%
1714
December11th to 20thNight
65%
948
28%
2888
16%
948
71%
948
25%
1834
December21st to endNight
63%
912
18%
4125
17%
903
69%
903
21%
2033

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
431332445%8%63%
74676
Night
43133245%6%8%61%
75062
TransparencyDay
12%37%6%12%17%17%
74426
Night
13%37%6%12%16%17%
74834
SeeingDay
5%5%18%33%30%9%
13231
Night
5%319%46%25%1
23551

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 10thDay
6%31431445%7%63%
1897
11th to 20thDay
8%423322346%64%
1815
21st to endDay
3423424445%65%
1980
February1st to 10thDay
3414424445%65%
1800
11th to 20thDay
5%424323346%63%
1749
21st to endDay
3412223447%70%
1480
March1st to 10thDay
33244235%5%8%61%
1800
11th to 20thDay
6%42342445%6%60%
1902
21st to endDay
3213223347%70%
2362
April1st to 10thDay
221323445%7%67%
2160
11th to 20thDay
2212213345%73%
2131
21st to endDay
4213313346%71%
2160
May1st to 10thDay
2212323347%71%
2160
11th to 20thDay
322232345%7%68%
2125
21st to endDay
32122245%7%8%67%
2399
June1st to 10thDay
111122346%8%72%
2340
11th to 20thDay
22123345%5%9%65%
2340
21st to endDay
22133245%7%11%60%
2222
July1st to 10thDay
4215%5%46%7%7%11%49%
2160
11th to 20thDay
32133245%7%11%59%
2160
21st to endDay
3312435%7%7%12%53%
2349
August1st to 10thDay
21123145%7%11%61%
2149
11th to 20thDay
5%325%5%45%6%7%12%46%
2123
21st to endDay
42145%25%6%8%11%52%
2376
September1st to 10thDay
5%425%5%346%7%10%47%
2160
11th to 20thDay
7%5%244345%6%10%50%
2038
21st to endDay
5%32342445%7%61%
1980
October1st to 10thDay
321232345%8%67%
1980
11th to 20thDay
6%31332346%8%63%
1905
21st to endDay
6%312212235%73%
1980
November1st to 10thDay
6%222222335%71%
1840
11th to 20thDay
431232335%5%70%
1710
21st to endDay
6%32332335%5%65%
1710
December1st to 10thDay
6%5%23422346%63%
1710
11th to 20thDay
3424435%46%8%57%
2161
21st to endDay
33133235%6%7%65%
3363
January1st to 10thNight
5%313223445%67%
2268
11th to 20thNight
8%2123235%5%6%64%
2184
21st to endNight
5%5%2432445%6%59%
2376
February1st to 10thNight
442332445%6%65%
2160
11th to 20thNight
5%31342445%7%59%
2098
21st to endNight
4312325%446%67%
1776
March1st to 10thNight
44243345%5%6%61%
2160
11th to 20thNight
6%5%1342346%6%61%
2052
21st to endNight
332332335%6%69%
1991
April1st to 10thNight
3313325%446%65%
1800
11th to 20thNight
321232335%7%69%
1777
21st to endNight
3312224445%71%
1800
May1st to 10thNight
421432345%7%66%
1800
11th to 20thNight
5%21443445%7%59%
1770
21st to endNight
2314425%5%6%8%59%
1867
June1st to 10thNight
3113325%6%8%12%57%
1620
11th to 20thNight
2124435%6%8%11%53%
1620
21st to endNight
32134246%8%12%56%
1727
July1st to 10thNight
3425%5%46%8%10%12%42%
1800
11th to 20thNight
31133345%7%12%58%
1800
21st to endNight
2314446%8%8%11%51%
1969
August1st to 10thNight
22134347%10%14%52%
1790
11th to 20thNight
33145%45%6%9%13%46%
1778
21st to endNight
23246%46%7%9%13%43%
1980
September1st to 10thNight
4325%5%5%6%5%7%10%49%
1800
11th to 20thNight
6%426%6%36%7%7%10%44%
1921
21st to endNight
5%4245%345%6%10%52%
1980
October1st to 10thNight
32134246%6%9%61%
1980
11th to 20thNight
7%21332445%6%62%
2050
21st to endNight
5%313212235%74%
2376
November1st to 10thNight
6%21221223475%
2220
11th to 20thNight
421231335%6%71%
2465
21st to endNight
5%313324346%66%
2470
December1st to 10thNight
6%3132235%5%7%62%
2470
11th to 20thNight
341332345%8%63%
3036
21st to endNight
33133135%5%8%64%
4331

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 10thDay
10%39%411%22%14%
1898
11th to 20thDay
13%41%213%19%13%
1815
21st to endDay
14%36%411%21%13%
1980
February1st to 10thDay
12%36%48%17%23%
1800
11th to 20thDay
14%37%48%19%18%
1759
21st to endDay
9%34%49%19%25%
1480
March1st to 10thDay
10%35%410%19%23%
1800
11th to 20thDay
13%37%46%14%25%
1902
21st to endDay
9%35%37%18%28%
2362
April1st to 10thDay
10%36%5%8%15%27%
2160
11th to 20thDay
7%34%38%16%32%
2134
21st to endDay
10%35%46%15%31%
2160
May1st to 10thDay
11%36%39%15%26%
2160
11th to 20thDay
12%38%5%11%16%18%
2128
21st to endDay
8%38%6%13%15%19%
2399
June1st to 10thDay
5%36%5%15%20%18%
2340
11th to 20thDay
8%36%7%10%20%19%
2340
21st to endDay
14%38%9%13%16%11%
2222
July1st to 10thDay
19%40%10%12%12%6%
2101
11th to 20thDay
11%38%7%20%16%9%
2097
21st to endDay
15%41%12%20%10%2
2219
August1st to 10thDay
10%38%9%21%15%7%
2136
11th to 20thDay
18%38%9%18%13%4
2123
21st to endDay
18%40%11%15%11%6%
2376
September1st to 10thDay
20%39%11%12%10%8%
2160
11th to 20thDay
20%38%7%12%15%7%
2038
21st to endDay
12%37%6%13%19%14%
1980
October1st to 10thDay
10%37%7%15%17%14%
1980
11th to 20thDay
11%36%6%15%15%17%
1905
21st to endDay
9%35%39%23%21%
1980
November1st to 10thDay
439%311%23%21%
1840
11th to 20thDay
6%39%6%12%22%16%
1710
21st to endDay
11%40%5%14%13%16%
1710
December1st to 10thDay
11%39%5%8%23%14%
1710
11th to 20thDay
18%32%5%16%20%10%
2159
21st to endDay
11%24%410%28%22%
3363
January1st to 10thNight
9%39%311%22%17%
2268
11th to 20thNight
12%41%410%19%14%
2184
21st to endNight
16%37%411%18%14%
2376
February1st to 10thNight
13%35%48%17%24%
2160
11th to 20thNight
16%37%5%7%14%21%
2098
21st to endNight
11%35%37%18%26%
1776
March1st to 10thNight
13%35%38%18%23%
2160
11th to 20thNight
15%36%47%12%26%
2052
21st to endNight
10%36%5%9%12%29%
1991
April1st to 10thNight
13%36%49%14%24%
1800
11th to 20thNight
9%34%5%8%13%30%
1777
21st to endNight
11%35%49%14%27%
1800
May1st to 10thNight
13%36%5%10%12%23%
1800
11th to 20thNight
16%39%5%12%13%14%
1771
21st to endNight
14%39%7%13%11%16%
1868
June1st to 10thNight
10%39%9%17%14%12%
1620
11th to 20thNight
14%38%8%11%15%14%
1620
21st to endNight
16%39%8%13%15%10%
1727
July1st to 10thNight
20%41%11%15%10%3
1750
11th to 20thNight
11%39%7%18%17%8%
1740
21st to endNight
18%42%10%20%9%1
1859
August1st to 10thNight
12%40%9%18%16%5%
1779
11th to 20thNight
16%38%11%20%13%2
1778
21st to endNight
19%40%11%13%12%5%
1980
September1st to 10thNight
19%40%12%14%8%7%
1800
11th to 20thNight
23%39%9%11%12%5%
1921
21st to endNight
15%38%8%13%14%13%
1980
October1st to 10thNight
11%37%9%14%14%15%
1980
11th to 20thNight
15%36%5%14%14%16%
2050
21st to endNight
9%35%210%19%24%
2376
November1st to 10thNight
5%39%29%24%22%
2220
11th to 20thNight
7%39%5%10%18%21%
2465
21st to endNight
11%39%6%12%14%19%
2470
December1st to 10thNight
11%40%6%10%19%15%
2470
11th to 20thNight
13%32%5%16%22%13%
3037
21st to endNight
12%24%5%11%25%23%
4331

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 10thDay
11%427%37%18%2
270
11th to 20thDay
6%6%22%40%25%2
245
21st to endDay
411%28%36%18%3
264
February1st to 10thDay
5%8%24%30%29%3
240
11th to 20thDay
10%12%24%34%18%2
240
21st to endDay
7%13%29%39%10%2
198
March1st to 10thDay
8%331%37%20%1
240
11th to 20thDay
6%13%34%30%13%5%
342
21st to endDay
7%14%33%33%12%2
462
April1st to 10thDay
5%13%36%34%11%1
420
11th to 20thDay
316%40%29%10%3
412
21st to endDay
7%12%32%39%10%
420
May1st to 10thDay
39%32%38%14%4
423
11th to 20thDay
28%30%40%18%2
448
21st to endDay
3424%44%23%2
547
June1st to 10thDay
1314%38%38%6%
630
11th to 20thDay
211%38%43%6%
630
21st to endDay
4111%33%43%8%
512
July1st to 10thDay
418%27%38%22%
446
11th to 20thDay
35%33%42%17%
444
21st to endDay
21434%43%16%
487
August1st to 10thDay
2421%52%21%
447
11th to 20thDay
5%17%26%39%23%
437
21st to endDay
317%26%40%23%
495
September1st to 10thDay
7%26%31%39%16%
450
11th to 20thDay
5%6%19%47%22%
328
21st to endDay
7%9%20%41%22%
270
October1st to 10thDay
429%28%41%16%
270
11th to 20thDay
10%111%29%33%16%
270
21st to endDay
9%413%28%33%13%
297
November1st to 10thDay
7%413%30%35%11%
270
11th to 20thDay
8%8%17%25%31%11%
270
21st to endDay
7%10%22%32%24%5%
270
December1st to 10thDay
9%5%14%32%35%6%
270
11th to 20thDay
49%24%39%21%1
270
21st to endDay
5%6%21%45%21%1
297
January1st to 10thNight
7%221%53%17%1
760
11th to 20thNight
8%317%52%19%
728
21st to endNight
6%5%24%48%15%1
792
February1st to 10thNight
5%5%25%45%20%1
720
11th to 20thNight
7%422%54%12%1
704
21st to endNight
6%5%30%50%8%
592
March1st to 10thNight
6%5%31%45%11%1
720
11th to 20thNight
9%5%26%45%15%1
720
21st to endNight
5%6%34%44%11%
605
April1st to 10thNight
47%32%47%10%
540
11th to 20thNight
38%38%44%7%
533
21st to endNight
46%36%47%7%
540
May1st to 10thNight
4429%53%10%
540
11th to 20thNight
5%5%28%50%11%
531
21st to endNight
3227%54%14%
584
June1st to 10thNight
2218%57%20%1
540
11th to 20thNight
2117%57%24%
540
21st to endNight
3112%49%34%
540
July1st to 10thNight
4111%41%40%2
525
11th to 20thNight
35%43%47%2
522
21st to endNight
316%39%49%2
591
August1st to 10thNight
21430%61%2
537
11th to 20thNight
315%30%56%5%
534
21st to endNight
416%33%54%4
594
September1st to 10thNight
5%15%34%53%2
540
11th to 20thNight
7%18%36%47%1
540
21st to endNight
6%19%42%40%2
540
October1st to 10thNight
4111%48%36%1
540
11th to 20thNight
8%112%51%26%2
610
21st to endNight
5%313%42%32%4
792
November1st to 10thNight
7%19%45%33%4
740
11th to 20thNight
4414%49%29%1
945
21st to endNight
6%322%46%20%2
950
December1st to 10thNight
7%214%51%24%1
950
11th to 20thNight
5%322%51%18%1
950
21st to endNight
5%422%52%15%2
922
Page generated at 2024-01-09 15:24:22. Version ac07

Copyright 2024 Attilla Danko


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