Walloper Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Walloper Lake clear sky chart from 2005-11-05 to 2019-07-16.

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
37%
17110
11%
54034
8%
17086
41%
17086
18%
37514

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
29%
896
6%
3136
5%
896
32%
896
9%
2470
January16th to endNight
35%
898
8%
3146
7%
898
39%
898
12%
2343
February1st to 15thNight
33%
817
11%
2771
9%
817
38%
817
12%
2062
February16th to endNight
35%
736
13%
2325
9%
736
41%
736
18%
1597
March1st to 15thNight
28%
840
12%
2496
8%
840
34%
840
14%
1797
March16th to endNight
31%
896
11%
2353
4%
896
36%
896
16%
1726
April1st to 15thNight
33%
839
11%
2099
4%
839
37%
839
18%
1577
April16th to endNight
31%
550
13%
1798
9%
550
38%
550
16%
1231
May1st to 15thNight
43%
419
12%
1680
18%
419
48%
419
18%
1073
May16th to endNight
46%
438
6%
1752
7%
438
48%
438
18%
1158
June1st to 15thNight
36%
420
3%
1282
0%
420
37%
420
20%
870
June16th to endNight
36%
420
3%
1260
0%
420
36%
420
23%
825
July1st to 15thNight
50%
400
6%
1379
2%
400
52%
400
30%
766
July16th to endNight
61%
410
12%
1503
15%
388
66%
388
37%
708
August1st to 15thNight
69%
384
19%
1528
27%
382
73%
382
38%
719
August16th to endNight
53%
671
21%
1913
15%
671
57%
671
34%
1138
September1st to 15thNight
57%
780
20%
1950
10%
780
60%
780
40%
1179
September16th to endNight
46%
776
19%
2115
12%
776
50%
776
28%
1357
October1st to 15thNight
43%
780
15%
2340
13%
780
48%
780
24%
1520
October16th to endNight
34%
832
14%
2659
8%
832
43%
832
18%
1792
November1st to 15thNight
26%
820
9%
2843
6%
820
31%
820
10%
2130
November16th to endNight
28%
889
8%
2989
5%
889
33%
889
10%
2295
December1st to 15thNight
35%
1057
11%
3175
8%
1057
38%
1057
14%
2384
December16th to endNight
24%
1142
9%
3542
4%
1142
29%
1142
9%
2797

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
9%10%48%7%46%5%5%7%30%
55300
Night
6%10%48%7%46%5%6%7%32%
54190
Cloud CoverDay
9%10%48%7%45%5%6%7%30%
55300
Night
7%9%48%7%45%5%6%7%32%
54193
TransparencyDay
51%5%13%19%8%1
54960
Night
48%6%15%20%8%
54034
SeeingDay
17%16%24%23%14%3
8604
Night
12%14%22%28%17%3
17123

By Month

Percentage Cloud Cover NW (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
5%11%6%12%11%6%7%6%6%6%19%
1463
16th to endDay
5%13%5%8%7%45%7%8%8%24%
1781
February1st to 15thDay
8%15%6%11%7%45%6%6%6%21%
1751
16th to endDay
313%7%12%8%45%6%6%6%26%
1721
March1st to 15thDay
5%14%6%11%9%47%6%6%6%20%
2124
16th to endDay
5%13%5%10%10%5%8%6%6%7%20%
2574
April1st to 15thDay
8%15%6%11%9%6%6%5%5%6%17%
2509
16th to endDay
8%15%6%9%8%46%5%6%7%21%
2764
May1st to 15thDay
9%12%48%7%36%5%5%7%28%
2931
16th to endDay
16%11%49%7%46%45%7%23%
3063
June1st to 15thDay
18%10%48%6%45%5%5%6%22%
3334
16th to endDay
14%7%47%8%46%5%5%7%27%
3360
July1st to 15thDay
8%5%25%5%36%6%6%7%42%
3166
16th to endDay
7%4245%2445%7%49%
2935
August1st to 15thDay
5%425%5%35%45%7%49%
2676
16th to endDay
7%6%26%5%35%5%5%7%45%
2640
September1st to 15thDay
9%7%25%5%2335%5%47%
2340
16th to endDay
15%7%36%6%35%5%47%33%
2174
October1st to 15thDay
10%11%46%6%35%45%7%35%
1950
16th to endDay
8%11%48%5%45%5%6%8%30%
1916
November1st to 15thDay
11%13%5%9%9%45%5%5%6%23%
1674
16th to endDay
6%14%6%8%8%46%7%6%6%22%
1615
December1st to 15thDay
410%7%12%8%47%6%6%7%25%
1442
16th to endDay
6%13%6%10%8%5%8%5%6%7%20%
1397
January1st to 15thNight
7%13%6%12%10%47%5%5%8%18%
3136
16th to endNight
5%11%5%10%8%5%7%6%6%8%22%
3146
February1st to 15thNight
8%14%6%11%7%35%5%5%6%25%
2759
16th to endNight
39%5%11%7%46%5%5%8%30%
2325
March1st to 15thNight
411%5%8%8%47%6%6%8%28%
2496
16th to endNight
39%5%8%9%5%8%6%6%8%28%
2349
April1st to 15thNight
410%410%8%5%7%6%6%6%29%
2099
16th to endNight
412%5%9%7%35%6%5%6%32%
1798
May1st to 15thNight
7%11%46%5%35%5%6%6%37%
1679
16th to endNight
11%8%37%6%35%6%5%8%32%
1752
June1st to 15thNight
13%7%36%7%35%6%6%9%30%
1282
16th to endNight
8%7%37%7%35%6%5%7%38%
1260
July1st to 15thNight
6%5%25%5%25%5%6%7%48%
1449
16th to endNight
6%32342345%7%56%
1598
August1st to 15thNight
431332446%7%56%
1536
16th to endNight
6%5%25%5%345%5%6%48%
1913
September1st to 15thNight
7%5%15%324447%53%
1950
16th to endNight
9%6%35%5%3445%8%42%
2115
October1st to 15thNight
8%8%37%6%345%5%6%40%
2340
16th to endNight
8%9%38%6%35%6%6%7%33%
2659
November1st to 15thNight
9%12%5%8%8%5%7%6%6%7%24%
2843
16th to endNight
7%14%7%9%9%46%5%5%7%22%
2989
December1st to 15thNight
5%12%6%9%8%46%6%6%7%25%
3175
16th to endNight
6%12%7%11%9%5%6%6%5%6%21%
3542

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
6%11%5%14%9%5%6%7%6%7%19%
1463
16th to endDay
6%13%5%9%7%45%6%8%7%24%
1781
February1st to 15thDay
8%15%6%9%8%46%6%5%6%22%
1751
16th to endDay
412%7%11%8%35%6%5%7%26%
1721
March1st to 15thDay
5%13%7%10%9%46%6%6%6%22%
2124
16th to endDay
6%12%6%10%9%5%6%6%7%7%20%
2574
April1st to 15thDay
9%14%5%11%9%5%7%6%5%6%18%
2509
16th to endDay
9%14%5%9%8%46%5%6%6%22%
2764
May1st to 15thDay
10%11%48%7%45%5%5%6%30%
2931
16th to endDay
16%10%47%6%45%5%5%7%24%
3063
June1st to 15thDay
18%9%48%7%45%5%6%6%22%
3334
16th to endDay
13%7%48%7%46%5%5%6%29%
3360
July1st to 15thDay
8%5%26%5%35%5%6%7%42%
3166
16th to endDay
7%425%5%3345%8%50%
2935
August1st to 15thDay
5%325%5%35%5%6%8%49%
2676
16th to endDay
7%5%25%5%35%46%7%45%
2640
September1st to 15thDay
9%7%26%5%23346%48%
2340
16th to endDay
15%7%36%6%35%45%6%34%
2174
October1st to 15thDay
10%9%47%6%35%45%7%36%
1950
16th to endDay
9%11%37%6%45%5%6%8%30%
1916
November1st to 15thDay
11%12%5%10%7%46%5%5%6%24%
1674
16th to endDay
7%15%6%7%8%46%6%6%7%23%
1615
December1st to 15thDay
412%5%12%8%46%6%5%7%26%
1442
16th to endDay
6%12%7%10%7%5%7%6%8%6%21%
1397
January1st to 15thNight
7%14%7%11%10%5%5%5%6%8%17%
3135
16th to endNight
6%12%5%11%9%5%6%5%7%8%22%
3146
February1st to 15thNight
9%14%6%10%7%345%5%6%26%
2759
16th to endNight
49%5%9%7%46%5%5%8%32%
2325
March1st to 15thNight
411%48%8%46%6%6%7%29%
2496
16th to endNight
410%48%8%5%7%7%7%7%28%
2353
April1st to 15thNight
5%10%5%9%8%46%7%6%7%29%
2099
16th to endNight
5%11%49%7%36%5%5%6%32%
1798
May1st to 15thNight
7%10%47%5%35%45%6%37%
1679
16th to endNight
11%7%37%7%35%5%6%9%31%
1752
June1st to 15thNight
14%5%48%6%25%5%8%8%30%
1282
16th to endNight
9%5%38%6%35%45%7%38%
1260
July1st to 15thNight
6%3245%25%6%6%7%49%
1449
16th to endNight
5%3133245%6%7%57%
1598
August1st to 15thNight
5%31242346%7%56%
1536
16th to endNight
6%5%25%5%45%45%8%48%
1913
September1st to 15thNight
6%425%42435%6%53%
1950
16th to endNight
10%6%35%43345%8%43%
2115
October1st to 15thNight
8%7%37%5%35%45%7%41%
2340
16th to endNight
9%7%46%7%35%47%7%34%
2659
November1st to 15thNight
10%11%48%8%47%6%5%5%26%
2843
16th to endNight
7%13%6%11%9%46%5%5%7%21%
2989
December1st to 15thNight
5%12%6%10%8%46%6%5%7%26%
3175
16th to endNight
6%13%6%11%8%5%7%6%5%5%22%
3542

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
61%8%14%11%2
1463
16th to endDay
52%7%17%17%41
1781
February1st to 15thDay
59%6%13%14%5%
1751
16th to endDay
55%5%14%15%9%
1721
March1st to 15thDay
59%6%13%14%4
2124
16th to endDay
58%5%15%16%3
2574
April1st to 15thDay
64%6%10%14%4
2509
16th to endDay
58%6%13%15%6%
2764
May1st to 15thDay
53%413%19%9%
2931
16th to endDay
57%413%18%5%
3067
June1st to 15thDay
59%5%11%15%7%1
3334
16th to endDay
52%5%13%18%9%
3360
July1st to 15thDay
38%5%11%24%16%3
3007
16th to endDay
31%412%30%18%3
2767
August1st to 15thDay
31%5%16%29%14%2
2659
16th to endDay
36%415%29%12%1
2640
September1st to 15thDay
37%313%28%15%1
2340
16th to endDay
48%5%14%20%8%2
2174
October1st to 15thDay
47%316%25%6%
1950
16th to endDay
49%7%18%18%5%
1916
November1st to 15thDay
58%6%11%17%5%
1674
16th to endDay
56%7%14%15%5%
1615
December1st to 15thDay
55%8%15%16%3
1442
16th to endDay
59%8%13%13%4
1397
January1st to 15thNight
63%6%14%12%2
3136
16th to endNight
56%7%15%15%4
3146
February1st to 15thNight
57%5%13%16%6%
2771
16th to endNight
48%5%17%19%8%
2325
March1st to 15thNight
50%7%16%18%6%
2496
16th to endNight
49%7%18%18%5%
2353
April1st to 15thNight
51%7%15%18%6%
2099
16th to endNight
49%5%15%20%8%
1798
May1st to 15thNight
45%5%14%22%11%1
1680
16th to endNight
47%6%18%20%7%
1752
June1st to 15thNight
46%6%15%23%7%1
1282
16th to endNight
43%417%22%10%1
1260
July1st to 15thNight
32%5%12%28%18%3
1379
16th to endNight
23%5%13%30%22%4
1503
August1st to 15thNight
24%417%30%19%4
1528
16th to endNight
33%415%27%16%2
1913
September1st to 15thNight
30%315%30%16%2
1950
16th to endNight
38%5%17%23%11%3
2115
October1st to 15thNight
41%5%16%26%9%
2340
16th to endNight
46%6%18%24%5%
2659
November1st to 15thNight
56%7%14%14%5%
2843
16th to endNight
60%6%14%12%5%
2989
December1st to 15thNight
55%6%14%18%3
3175
16th to endNight
60%8%12%13%5%
3542

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
9%14%12%26%23%14%
120
16th to endDay
13%21%29%22%12%
128
February1st to 15thDay
18%17%30%25%7%
231
16th to endDay
9%21%30%22%13%1
308
March1st to 15thDay
23%23%25%18%8%1
390
16th to endDay
18%26%25%17%8%2
416
April1st to 15thDay
25%19%29%16%8%1
389
16th to endDay
21%22%28%17%8%2
378
May1st to 15thDay
20%15%24%25%10%3
408
16th to endDay
20%13%17%28%16%4
458
June1st to 15thDay
23%14%23%21%14%1
829
16th to endDay
17%11%26%25%15%3
855
July1st to 15thDay
13%15%25%28%14%3
641
16th to endDay
9%9%22%33%19%5%
441
August1st to 15thDay
6%6%22%29%25%9%
359
16th to endDay
11%12%30%26%15%4
396
September1st to 15thDay
16%15%22%24%17%3
375
16th to endDay
22%13%27%18%13%4
375
October1st to 15thDay
23%18%23%19%12%3
375
16th to endDay
14%15%18%26%20%4
236
November1st to 15thDay
25%25%24%13%11%
128
16th to endDay
15%21%25%15%14%8%
120
December1st to 15thDay
7%19%18%16%27%10%
120
16th to endDay
10%22%25%25%10%4
128
January1st to 15thNight
17%15%20%29%15%2
900
16th to endNight
11%15%24%31%15%2
898
February1st to 15thNight
16%14%17%34%13%3
824
16th to endNight
8%15%24%28%21%1
736
March1st to 15thNight
13%23%23%23%12%3
840
16th to endNight
11%22%24%22%14%3
896
April1st to 15thNight
11%17%23%27%16%2
839
16th to endNight
10%17%30%26%13%2
550
May1st to 15thNight
10%12%23%34%14%3
420
16th to endNight
15%5%22%29%24%3
439
June1st to 15thNight
14%11%26%29%14%3
420
16th to endNight
10%10%30%28%16%3
420
July1st to 15thNight
8%7%26%35%19%1
400
16th to endNight
8%221%35%28%4
410
August1st to 15thNight
7%314%30%36%8%
384
16th to endNight
9%7%21%29%27%5%
671
September1st to 15thNight
9%7%17%25%30%9%
780
16th to endNight
14%13%18%25%22%5%
776
October1st to 15thNight
11%13%22%28%19%3
780
16th to endNight
14%17%24%23%16%3
832
November1st to 15thNight
18%19%25%25%9%1
820
16th to endNight
16%19%22%24%13%3
889
December1st to 15thNight
12%14%22%30%17%2
1057
16th to endNight
13%20%24%28%10%2
1142
Page generated at 2019-07-17 05:53:10. Version ac04

Copyright 2019 A. Danko


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