Big Meadows
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Big Meadows clear sky chart from 2005-11-05 to 2018-02-14.

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
41%
15938
21%
48860
13%
15902
50%
15902
25%
31015

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
26%
776
22%
2528
9%
776
42%
776
20%
1588
January16th to endNight
26%
832
22%
2704
11%
832
42%
832
21%
1709
February1st to 15thNight
25%
757
19%
2468
8%
757
40%
757
22%
1529
February16th to endNight
19%
631
23%
1919
8%
631
36%
631
21%
1216
March1st to 15thNight
26%
720
22%
1980
10%
720
38%
720
24%
1295
March16th to endNight
27%
768
19%
2112
10%
768
36%
768
23%
1423
April1st to 15thNight
28%
718
19%
1814
5%
718
37%
718
28%
1193
April16th to endNight
41%
705
20%
1785
9%
705
46%
705
31%
1195
May1st to 15thNight
40%
540
16%
1620
8%
540
45%
540
22%
1103
May16th to endNight
52%
444
16%
1567
12%
444
57%
444
24%
975
June1st to 15thNight
61%
360
18%
1440
20%
360
67%
360
24%
834
June16th to endNight
63%
360
18%
1440
20%
360
68%
360
24%
852
July1st to 15thNight
62%
430
12%
1450
12%
430
63%
430
23%
938
July16th to endNight
76%
564
16%
1595
13%
531
79%
531
38%
930
August1st to 15thNight
67%
539
18%
1609
13%
536
67%
536
28%
1059
August16th to endNight
62%
717
17%
1863
13%
717
63%
717
28%
1277
September1st to 15thNight
60%
720
24%
1800
16%
720
63%
720
34%
1193
September16th to endNight
51%
717
21%
2007
18%
717
54%
717
27%
1343
October1st to 15thNight
50%
720
22%
2160
20%
720
56%
720
26%
1378
October16th to endNight
41%
768
30%
2304
18%
768
56%
768
31%
1359
November1st to 15thNight
41%
760
25%
2330
16%
760
52%
760
28%
1420
November16th to endNight
37%
780
23%
2723
16%
780
50%
780
25%
1578
December1st to 15thNight
31%
780
18%
2730
10%
780
42%
780
18%
1769
December16th to endNight
32%
832
21%
2912
12%
832
46%
832
20%
1859

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
14%6%25%5%35%5%5%7%38%
49198
Night
13%6%25%42445%7%42%
49051
Cloud CoverDay
14%6%35%5%35%5%5%7%38%
49208
Night
13%6%25%42445%6%43%
49055
TransparencyDay
43%6%11%20%15%2
48907
Night
39%6%12%22%16%3
48860
SeeingDay
18%9%23%23%16%7%
6079
Night
16%8%26%31%15%1
15947

By Month

Percentage Cloud Cover NE (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
13%7%25%5%3445%6%38%
1738
16th to endDay
14%8%35%43445%5%40%
1872
February1st to 15thDay
13%10%46%43445%437%
1695
16th to endDay
13%8%35%5%3445%6%38%
1550
March1st to 15thDay
15%8%245%23435%42%
1969
16th to endDay
16%9%45%425%5%45%35%
2112
April1st to 15thDay
12%6%26%5%23447%43%
2134
16th to endDay
17%5%25%5%24446%40%
2184
May1st to 15thDay
19%5%25%5%36%5%5%7%32%
2331
16th to endDay
13%7%26%5%345%6%7%34%
2545
June1st to 15thDay
12%325%6%46%6%6%9%37%
2520
16th to endDay
10%5%26%6%36%5%7%8%37%
2520
July1st to 15thDay
12%7%36%6%36%6%6%8%31%
2418
16th to endDay
9%5%26%7%5%7%8%7%9%32%
2465
August1st to 15thDay
10%6%36%8%47%7%7%8%28%
2340
16th to endDay
13%6%26%6%46%7%6%8%30%
2326
September1st to 15thDay
13%5%35%6%3445%6%42%
2160
16th to endDay
16%7%36%6%35%5%5%6%34%
1952
October1st to 15thDay
18%6%25%323345%43%
1800
16th to endDay
13%5%25%423445%47%
1920
November1st to 15thDay
13%5%2432435%5%48%
1857
16th to endDay
16%414434336%47%
1566
December1st to 15thDay
16%6%25%5%235%5%5%41%
1560
16th to endDay
15%9%35%5%2445%7%36%
1664
January1st to 15thNight
13%7%344345%46%42%
2528
16th to endNight
15%8%2442445%5%41%
2704
February1st to 15thNight
13%7%25%4345%5%6%41%
2466
16th to endNight
13%6%36%5%25%45%6%40%
1919
March1st to 15thNight
16%6%25%424347%41%
1968
16th to endNight
15%8%35%423445%42%
2112
April1st to 15thNight
11%7%25%425%46%7%42%
1814
16th to endNight
12%6%3442445%7%42%
1785
May1st to 15thNight
15%6%26%6%25%446%38%
1620
16th to endNight
12%5%25%5%2445%9%42%
1565
June1st to 15thNight
7%5%25%435%5%5%10%43%
1440
16th to endNight
8%5%25%6%345%5%10%43%
1440
July1st to 15thNight
10%5%35%435%5%7%7%40%
1538
16th to endNight
5%313435%6%8%14%43%
1703
August1st to 15thNight
8%5%25%6%345%7%8%40%
1620
16th to endNight
10%5%36%5%35%5%7%9%38%
1863
September1st to 15thNight
13%425%4335%5%7%45%
1800
16th to endNight
14%6%25%6%24345%44%
2007
October1st to 15thNight
15%5%244335%46%44%
2160
16th to endNight
13%414424346%51%
2304
November1st to 15thNight
13%8%33323335%48%
2330
16th to endNight
14%5%2342445%6%46%
2723
December1st to 15thNight
15%8%35%5%3444439%
2730
16th to endNight
14%7%35%43445%6%38%
2912

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
14%7%25%5%34446%40%
1738
16th to endDay
14%8%35%5%2444441%
1872
February1st to 15thDay
12%9%46%5%34345%38%
1695
16th to endDay
12%8%36%435%45%6%39%
1550
March1st to 15thDay
14%7%35%5%23435%42%
1980
16th to endDay
16%8%36%5%25%5%45%35%
2111
April1st to 15thDay
11%6%35%5%3445%6%44%
2134
16th to endDay
17%5%25%434446%39%
2184
May1st to 15thDay
18%6%35%5%36%45%6%33%
2331
16th to endDay
15%6%35%5%35%5%6%8%34%
2545
June1st to 15thDay
12%425%5%46%5%6%9%37%
2520
16th to endDay
10%326%6%35%6%6%9%37%
2520
July1st to 15thDay
12%6%35%6%46%6%6%9%30%
2418
16th to endDay
9%5%36%6%48%8%7%10%31%
2465
August1st to 15thDay
12%7%36%7%47%6%7%8%28%
2340
16th to endDay
13%5%36%6%47%6%7%7%30%
2326
September1st to 15thDay
13%6%26%5%34446%42%
2160
16th to endDay
17%7%25%6%335%5%6%34%
1952
October1st to 15thDay
19%5%25%323345%43%
1800
16th to endDay
13%5%245%23345%48%
1920
November1st to 15thDay
13%5%24323346%49%
1857
16th to endDay
16%414424345%47%
1566
December1st to 15thDay
15%5%36%42335%6%41%
1560
16th to endDay
15%9%35%42345%7%37%
1664
January1st to 15thNight
14%6%3442445%6%42%
2528
16th to endNight
15%7%34424445%42%
2704
February1st to 15thNight
13%6%25%5%2446%5%43%
2459
16th to endNight
12%6%36%5%245%6%6%42%
1919
March1st to 15thNight
16%5%25%424446%43%
1980
16th to endNight
15%7%35%433445%42%
2112
April1st to 15thNight
12%7%24435%45%7%42%
1814
16th to endNight
13%6%3442445%7%43%
1785
May1st to 15thNight
16%5%36%6%24347%37%
1619
16th to endNight
13%5%25%42445%9%42%
1565
June1st to 15thNight
10%4245%345%6%9%44%
1440
16th to endNight
9%425%5%45%5%5%9%42%
1440
July1st to 15thNight
10%6%25%435%6%6%7%40%
1538
16th to endNight
5%323435%6%10%11%43%
1703
August1st to 15thNight
9%6%25%7%35%45%8%40%
1620
16th to endNight
10%5%26%6%35%6%6%9%36%
1863
September1st to 15thNight
14%4144235%5%7%45%
1800
16th to endNight
16%6%25%5%23445%42%
2007
October1st to 15thNight
17%423433446%43%
2160
16th to endNight
12%414324345%52%
2304
November1st to 15thNight
13%6%35%333345%48%
2330
16th to endNight
15%423423446%47%
2723
December1st to 15thNight
15%7%36%425%435%39%
2730
16th to endNight
14%7%35%42445%6%39%
2912

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
43%6%11%18%16%4
1739
16th to endDay
43%5%10%21%16%3
1872
February1st to 15thDay
46%5%9%20%15%3
1697
16th to endDay
42%6%11%22%15%1
1550
March1st to 15thDay
43%5%9%21%16%3
1980
16th to endDay
48%5%9%18%14%3
2112
April1st to 15thDay
38%6%10%20%18%5%
2134
16th to endDay
43%5%9%18%17%5%
2184
May1st to 15thDay
48%6%12%17%12%1
2331
16th to endDay
44%8%13%21%10%1
2549
June1st to 15thDay
40%9%14%21%13%
2520
16th to endDay
39%9%15%20%13%1
2520
July1st to 15thDay
45%9%12%17%12%2
2277
16th to endDay
42%10%12%20%12%1
2310
August1st to 15thDay
47%8%13%18%12%
2327
16th to endDay
45%9%11%21%10%1
2326
September1st to 15thDay
40%6%11%17%19%3
2160
16th to endDay
47%5%9%20%16%1
1952
October1st to 15thDay
41%48%25%15%4
1800
16th to endDay
36%48%26%21%3
1920
November1st to 15thDay
36%410%21%20%5%
1857
16th to endDay
37%5%8%24%20%3
1566
December1st to 15thDay
41%6%11%22%13%4
1560
16th to endDay
45%412%22%13%1
1664
January1st to 15thNight
40%5%11%17%18%6%
2528
16th to endNight
41%5%10%22%18%2
2704
February1st to 15thNight
40%412%23%15%3
2468
16th to endNight
39%5%11%23%17%2
1919
March1st to 15thNight
40%5%10%26%13%2
1980
16th to endNight
41%6%11%21%15%2
2112
April1st to 15thNight
38%5%12%21%17%3
1814
16th to endNight
38%5%11%20%17%5%
1785
May1st to 15thNight
46%5%12%20%13%2
1620
16th to endNight
38%8%16%23%11%1
1567
June1st to 15thNight
34%8%14%27%13%1
1440
16th to endNight
36%8%15%19%17%2
1440
July1st to 15thNight
39%10%17%18%12%3
1450
16th to endNight
26%9%22%25%15%
1595
August1st to 15thNight
39%7%13%23%14%1
1609
16th to endNight
40%8%14%24%10%1
1863
September1st to 15thNight
35%7%13%20%19%3
1800
16th to endNight
42%6%9%21%18%2
2007
October1st to 15thNight
40%5%9%23%17%3
2160
16th to endNight
33%5%7%27%22%3
2304
November1st to 15thNight
38%38%20%20%7%
2330
16th to endNight
36%49%24%21%4
2723
December1st to 15thNight
45%5%9%21%14%3
2730
16th to endNight
43%5%12%22%13%2
2912

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
25%26%29%13%5%
134
16th to endDay
25%28%28%13%3
144
February1st to 15thDay
26%31%36%5%
130
16th to endDay
21%20%32%23%2
173
March1st to 15thDay
22%16%29%24%7%
270
16th to endDay
20%13%34%20%7%3
288
April1st to 15thDay
15%18%24%26%13%2
270
16th to endDay
23%7%26%18%17%5%
270
May1st to 15thDay
24%15%25%15%13%4
288
16th to endDay
21%426%20%17%9%
331
June1st to 15thDay
14%5%25%26%20%6%
315
16th to endDay
12%5%28%28%20%5%
315
July1st to 15thDay
19%223%26%20%6%
305
16th to endDay
7%211%35%27%15%
326
August1st to 15thDay
15%116%26%25%14%
313
16th to endDay
12%11%31%22%22%
332
September1st to 15thDay
15%5%15%23%21%18%
315
16th to endDay
25%218%20%21%12%
314
October1st to 15thDay
21%318%28%20%7%
315
16th to endDay
13%14%26%24%17%3
336
November1st to 15thDay
19%8%22%29%16%3
313
16th to endDay
17%17%31%23%9%
96
December1st to 15thDay
18%17%34%16%11%1
90
16th to endDay
26%17%39%12%4
96
January1st to 15thNight
18%17%31%25%6%
780
16th to endNight
20%12%36%28%1
832
February1st to 15thNight
18%13%37%29%1
760
16th to endNight
16%18%40%22%2
631
March1st to 15thNight
19%14%34%25%5%
720
16th to endNight
16%15%35%23%7%1
768
April1st to 15thNight
15%16%34%25%6%
718
16th to endNight
16%8%28%32%12%1
705
May1st to 15thNight
19%6%26%29%17%1
540
16th to endNight
15%319%36%23%2
446
June1st to 15thNight
10%218%40%26%2
360
16th to endNight
8%213%48%26%
360
July1st to 15thNight
13%214%34%34%1
430
16th to endNight
5%9%38%39%7%
564
August1st to 15thNight
10%10%41%32%3
539
16th to endNight
13%12%35%33%4
717
September1st to 15thNight
14%214%32%31%5%
720
16th to endNight
20%215%30%28%4
717
October1st to 15thNight
20%6%17%30%21%4
720
16th to endNight
15%9%29%29%14%1
768
November1st to 15thNight
16%10%25%31%13%2
760
16th to endNight
18%11%29%28%12%
780
December1st to 15thNight
19%9%31%29%8%
780
16th to endNight
18%11%30%36%3
832
Page generated at 2018-02-15 10:58:46. Version ac04

Copyright 2018 A. Danko


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