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 2005-11-05 to 2018-11-30.

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
72%
16854
32%
51947
27%
16814
77%
16814
46%
26210

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
73%
776
37%
2328
31%
776
78%
776
47%
1193
January16th to endNight
70%
832
37%
2496
31%
832
76%
832
47%
1273
February1st to 15thNight
67%
760
36%
2286
27%
756
77%
756
52%
1101
February16th to endNight
68%
684
35%
2050
27%
684
74%
684
54%
966
March1st to 15thNight
63%
780
34%
2327
23%
780
71%
780
49%
1177
March16th to endNight
62%
696
38%
2152
26%
696
73%
696
51%
1029
April1st to 15thNight
57%
584
38%
1948
26%
584
73%
584
48%
878
April16th to endNight
58%
579
36%
1929
29%
579
72%
579
52%
845
May1st to 15thNight
56%
584
29%
1949
24%
584
69%
584
45%
933
May16th to endNight
67%
609
26%
1979
27%
609
73%
609
41%
1021
June1st to 15thNight
73%
585
26%
1755
25%
585
77%
585
49%
877
June16th to endNight
76%
585
24%
1833
25%
585
79%
585
43%
948
July1st to 15thNight
79%
555
20%
1850
23%
555
80%
555
38%
993
July16th to endNight
82%
612
23%
1931
28%
579
84%
579
37%
1044
August1st to 15thNight
85%
575
26%
1908
31%
572
86%
572
40%
978
August16th to endNight
82%
621
22%
2070
26%
621
82%
621
31%
1184
September1st to 15thNight
78%
585
23%
1973
24%
585
79%
585
31%
1138
September16th to endNight
71%
582
23%
2145
27%
582
72%
582
28%
1232
October1st to 15thNight
80%
585
35%
2145
38%
585
82%
585
45%
975
October16th to endNight
76%
818
39%
2482
31%
818
79%
818
53%
1177
November1st to 15thNight
81%
887
39%
2527
28%
887
85%
887
63%
1155
November16th to endNight
77%
1050
39%
2730
24%
1050
82%
1050
61%
1358
December1st to 15thNight
75%
975
36%
2535
26%
975
77%
975
51%
1394
December16th to endNight
70%
955
39%
2619
28%
955
75%
955
53%
1341

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
321232345%7%62%
52308
Night
321332445%7%60%
52173
Cloud CoverDay
421232345%7%62%
52306
Night
421332345%7%60%
52173
TransparencyDay
20%5%9%19%24%20%
52028
Night
20%5%9%18%23%21%
51955
SeeingDay
5%416%31%30%12%
6571
Night
4214%46%29%2
16865

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
8%314313345%58%
1940
16th to endDay
4422213335%65%
2080
February1st to 15thDay
2313323445%66%
1900
16th to endDay
2211213346%70%
1710
March1st to 15thDay
3313323447%63%
1960
16th to endDay
4212212346%67%
2422
April1st to 15thDay
121222335%5%68%
2330
16th to endDay
1212212345%72%
2306
May1st to 15thDay
1112323346%69%
2331
16th to endDay
21122345%7%67%
2480
June1st to 15thDay
1122345%7%69%
2535
16th to endDay
2233245%6%11%58%
2450
July1st to 15thDay
4214435%6%6%10%51%
2340
16th to endDay
3313435%7%7%11%48%
2469
August1st to 15thDay
31134245%7%11%53%
2294
16th to endDay
4213425%6%8%11%48%
2484
September1st to 15thDay
5%425%5%245%7%10%44%
2316
16th to endDay
7%42342445%8%51%
2145
October1st to 15thDay
31221345%7%66%
2145
16th to endDay
7%212213245%68%
2090
November1st to 15thDay
5%211212235%70%
1975
16th to endDay
4212212245%70%
1885
December1st to 15thDay
45%23422246%60%
1755
16th to endDay
34133135%5%6%62%
1966
January1st to 15thNight
6%31222345%5%61%
2328
16th to endNight
5%31331335%6%61%
2496
February1st to 15thNight
2313313345%67%
2282
16th to endNight
2212314347%66%
2050
March1st to 15thNight
3323323445%63%
2327
16th to endNight
331321325%6%66%
2152
April1st to 15thNight
222224346%67%
1948
16th to endNight
22222444470%
1929
May1st to 15thNight
421332335%7%63%
1949
16th to endNight
3213425%46%8%57%
1978
June1st to 15thNight
113315%6%8%12%55%
1755
16th to endNight
21134245%8%11%53%
1833
July1st to 15thNight
2214435%7%8%11%48%
1950
16th to endNight
3213335%7%8%11%48%
2051
August1st to 15thNight
2233347%9%14%48%
1919
16th to endNight
23135%47%7%9%13%40%
2070
September1st to 15thNight
3225%5%46%5%6%10%46%
1973
16th to endNight
6%425%5%35%6%6%9%44%
2145
October1st to 15thNight
31123235%6%8%61%
2145
16th to endNight
5%212212235%69%
2482
November1st to 15thNight
411212235%74%
2527
16th to endNight
412113235%73%
2730
December1st to 15thNight
4312223447%61%
2535
16th to endNight
331331345%5%65%
2619

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
8%323423345%59%
1940
16th to endDay
5%422312335%66%
2080
February1st to 15thDay
231332334467%
1900
16th to endDay
2211313245%70%
1710
March1st to 15thDay
333313446%62%
1960
16th to endDay
4212212346%68%
2420
April1st to 15thDay
221231335%5%69%
2330
16th to endDay
222213335%72%
2306
May1st to 15thDay
2212212446%69%
2331
16th to endDay
21221346%6%68%
2480
June1st to 15thDay
1121345%7%70%
2535
16th to endDay
311232447%10%58%
2450
July1st to 15thDay
5%214425%5%6%9%52%
2340
16th to endDay
4314425%6%7%11%48%
2469
August1st to 15thDay
41134245%6%11%53%
2294
16th to endDay
5%2134346%7%12%48%
2484
September1st to 15thDay
7%425%425%47%10%44%
2316
16th to endDay
8%42442446%6%52%
2145
October1st to 15thDay
31221245%8%66%
2145
16th to endDay
7%21121223469%
2090
November1st to 15thDay
5%21211235%71%
1975
16th to endDay
422212235%70%
1885
December1st to 15thDay
5%5%13323236%61%
1755
16th to endDay
341231445%6%62%
1966
January1st to 15thNight
6%31222345%5%62%
2328
16th to endNight
6%313323346%61%
2496
February1st to 15thNight
2313223345%67%
2282
16th to endNight
3212223447%66%
2050
March1st to 15thNight
5%313223346%62%
2327
16th to endNight
3313212446%66%
2152
April1st to 15thNight
3212323345%67%
1948
16th to endNight
2212213345%70%
1929
May1st to 15thNight
423323346%64%
1949
16th to endNight
32133245%6%7%58%
1978
June1st to 15thNight
1133246%8%11%55%
1755
16th to endNight
22123245%7%11%54%
1833
July1st to 15thNight
3213436%6%8%11%48%
1950
16th to endNight
4313335%7%8%10%48%
2051
August1st to 15thNight
31134346%9%13%47%
1919
16th to endNight
33145%46%8%8%13%41%
2070
September1st to 15thNight
4216%5%35%6%7%10%46%
1973
16th to endNight
6%5%245%45%5%6%9%44%
2145
October1st to 15thNight
3223135%6%7%62%
2145
16th to endNight
6%21221223470%
2482
November1st to 15thNight
32121224474%
2527
16th to endNight
412112235%72%
2730
December1st to 15thNight
5%312223446%62%
2535
16th to endNight
4312223445%65%
2619

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
26%36%19%30%12%
1941
16th to endDay
21%26%17%36%15%
2080
February1st to 15thDay
19%46%14%24%30%
1901
16th to endDay
15%35%13%32%29%
1710
March1st to 15thDay
19%45%18%23%29%
1960
16th to endDay
18%3411%27%35%
2422
April1st to 15thDay
15%36%11%24%38%
2330
16th to endDay
13%35%10%21%44%
2306
May1st to 15thDay
15%36%15%23%35%
2331
16th to endDay
14%48%17%24%29%
2483
June1st to 15thDay
11%48%21%30%24%
2535
16th to endDay
18%6%13%22%23%15%
2450
July1st to 15thDay
26%8%15%24%18%6%
2211
16th to endDay
23%9%15%29%17%4
2326
August1st to 15thDay
21%8%15%29%19%4
2281
16th to endDay
25%9%17%25%16%6%
2484
September1st to 15thDay
31%9%16%19%16%6%
2316
16th to endDay
29%7%11%19%21%10%
2145
October1st to 15thDay
15%6%13%23%22%17%
2145
16th to endDay
20%25%15%28%27%
2090
November1st to 15thDay
16%36%23%29%19%
1975
16th to endDay
16%38%17%28%25%
1885
December1st to 15thDay
24%37%18%30%14%
1755
16th to endDay
20%36%23%32%12%
1966
January1st to 15thNight
22%46%16%32%17%
2328
16th to endNight
22%35%14%33%19%
2496
February1st to 15thNight
18%35%13%24%33%
2292
16th to endNight
17%25%13%29%30%
2050
March1st to 15thNight
21%3416%22%31%
2327
16th to endNight
18%45%13%22%34%
2152
April1st to 15thNight
18%37%11%20%39%
1948
16th to endNight
15%46%15%18%39%
1929
May1st to 15thNight
20%5%7%16%20%30%
1950
16th to endNight
22%7%8%19%17%24%
1980
June1st to 15thNight
17%7%11%24%24%13%
1755
16th to endNight
21%7%14%21%22%13%
1833
July1st to 15thNight
23%9%19%26%15%4
1850
16th to endNight
24%9%16%30%15%3
1931
August1st to 15thNight
20%9%18%27%20%3
1908
16th to endNight
29%10%16%24%15%4
2070
September1st to 15thNight
29%10%19%20%13%7%
1973
16th to endNight
33%7%12%19%16%9%
2145
October1st to 15thNight
18%6%14%23%19%17%
2145
16th to endNight
19%2415%27%30%
2482
November1st to 15thNight
13%37%20%30%24%
2527
16th to endNight
15%27%13%26%33%
2730
December1st to 15thNight
21%5%6%20%26%19%
2535
16th to endNight
19%35%18%32%19%
2619

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
11%415%36%26%5%
135
16th to endDay
38%17%38%28%3
144
February1st to 15thDay
35%13%31%37%8%
135
16th to endDay
6%11%18%37%22%3
120
March1st to 15thDay
7%222%38%23%5%
145
16th to endDay
311%30%34%15%4
352
April1st to 15thDay
314%35%29%13%2
329
16th to endDay
314%34%32%11%3
318
May1st to 15thDay
212%37%33%12%1
348
16th to endDay
35%27%38%21%2
439
June1st to 15thDay
1111%34%42%8%
570
16th to endDay
39%34%41%11%
485
July1st to 15thDay
5%7%27%35%22%
365
16th to endDay
315%33%34%22%
391
August1st to 15thDay
31423%42%24%
359
16th to endDay
46%28%32%27%
396
September1st to 15thDay
7%6%29%33%22%
351
16th to endDay
11%18%18%39%20%
180
October1st to 15thDay
7%18%23%37%21%
180
16th to endDay
15%9%25%30%19%
192
November1st to 15thDay
8%311%22%38%14%
180
16th to endDay
8%6%10%26%35%10%
178
December1st to 15thDay
10%5%12%24%38%8%
135
16th to endDay
6%414%39%31%2
144
January1st to 15thNight
7%13%55%21%1
780
16th to endNight
7%413%50%23%
832
February1st to 15thNight
4319%48%22%1
764
16th to endNight
3320%60%11%
684
March1st to 15thNight
6%322%51%15%1
780
16th to endNight
5%423%48%17%1
696
April1st to 15thNight
26%30%48%11%
584
16th to endNight
25%30%52%8%
579
May1st to 15thNight
4429%52%9%
585
16th to endNight
3120%57%15%
611
June1st to 15thNight
118%54%24%
585
16th to endNight
313%44%38%
585
July1st to 15thNight
39%39%45%2
555
16th to endNight
45%37%47%3
612
August1st to 15thNight
2327%61%4
575
16th to endNight
4429%56%5%
621
September1st to 15thNight
416%30%55%3
585
16th to endNight
9%8%38%41%2
582
October1st to 15thNight
49%46%37%1
585
16th to endNight
7%19%38%38%5%
818
November1st to 15thNight
418%44%36%3
887
16th to endNight
5%211%46%30%3
1050
December1st to 15thNight
7%110%50%27%1
975
16th to endNight
4315%54%20%2
955
Page generated at 2018-12-01 10:35:34. Version ac04

Copyright 2018 A. Danko


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