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 2017-09-24.

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%
14773
11%
46772
7%
14749
41%
14749
17%
32596

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
25%
746
6%
2686
5%
746
29%
746
8%
2124
January16th to endNight
34%
769
8%
2697
7%
769
37%
769
12%
2031
February1st to 15thNight
34%
697
9%
2368
7%
697
39%
697
12%
1770
February16th to endNight
37%
632
12%
1996
8%
632
43%
632
18%
1358
March1st to 15thNight
25%
720
10%
2139
5%
720
31%
720
13%
1554
March16th to endNight
28%
768
10%
2017
3%
768
33%
768
14%
1506
April1st to 15thNight
34%
719
10%
1799
4%
719
38%
719
18%
1348
April16th to endNight
33%
477
13%
1557
9%
477
40%
477
16%
1078
May1st to 15thNight
40%
359
11%
1440
16%
359
45%
359
17%
943
May16th to endNight
43%
374
5%
1496
6%
374
44%
374
16%
1018
June1st to 15thNight
36%
360
2%
1098
0%
360
36%
360
20%
745
June16th to endNight
34%
360
3%
1080
0%
360
34%
360
23%
708
July1st to 15thNight
52%
340
5%
1172
1%
340
53%
340
33%
632
July16th to endNight
60%
376
12%
1372
14%
354
66%
354
35%
657
August1st to 15thNight
69%
360
18%
1432
24%
358
73%
358
37%
684
August16th to endNight
51%
619
20%
1765
15%
619
56%
619
33%
1061
September1st to 15thNight
59%
720
20%
1800
10%
720
62%
720
42%
1066
September16th to endNight
46%
692
20%
1883
12%
692
50%
692
29%
1203
October1st to 15thNight
43%
660
15%
1980
13%
660
48%
660
24%
1287
October16th to endNight
32%
704
13%
2249
6%
704
41%
704
17%
1559
November1st to 15thNight
25%
700
10%
2427
6%
700
31%
700
11%
1794
November16th to endNight
29%
762
8%
2562
4%
762
33%
762
10%
1986
December1st to 15thNight
31%
903
10%
2721
6%
903
34%
903
12%
2093
December16th to endNight
25%
956
8%
3036
4%
956
30%
956
9%
2391

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%6%7%29%
48180
Night
7%10%48%7%46%5%6%7%32%
46928
Cloud CoverDay
9%10%48%7%45%5%6%7%30%
48180
Night
7%10%48%7%45%5%6%7%32%
46931
TransparencyDay
51%5%14%19%8%1
47840
Night
49%6%15%19%7%1
46772
SeeingDay
17%17%25%23%13%3
6290
Night
12%15%23%27%16%3
14786

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%10%5%12%11%6%8%6%6%6%19%
1253
16th to endDay
6%14%5%8%7%45%7%8%8%24%
1527
February1st to 15thDay
8%15%6%10%7%45%6%6%6%21%
1495
16th to endDay
414%6%10%8%45%6%6%6%26%
1478
March1st to 15thDay
5%15%7%11%9%47%5%7%6%18%
1821
16th to endDay
5%14%5%10%10%5%8%7%6%6%19%
2206
April1st to 15thDay
8%15%6%10%9%6%7%5%5%6%17%
2149
16th to endDay
8%15%7%10%8%47%5%6%7%19%
2400
May1st to 15thDay
10%13%48%7%46%5%5%6%27%
2511
16th to endDay
17%12%49%7%46%46%6%20%
2615
June1st to 15thDay
19%10%48%6%45%5%5%6%22%
2858
16th to endDay
14%7%47%8%46%6%5%7%27%
2880
July1st to 15thDay
8%5%25%5%26%5%6%7%43%
2714
16th to endDay
8%4246%25%45%7%48%
2702
August1st to 15thDay
5%425%5%35%46%7%47%
2520
16th to endDay
7%6%26%5%35%5%6%7%43%
2436
September1st to 15thDay
9%7%25%5%2335%6%48%
2160
16th to endDay
14%7%35%6%36%6%5%7%33%
1935
October1st to 15thDay
10%9%46%6%36%45%7%36%
1650
16th to endDay
9%12%48%5%45%5%7%7%27%
1622
November1st to 15thDay
11%13%6%9%8%445%5%6%24%
1430
16th to endDay
7%15%7%7%8%46%7%6%6%22%
1385
December1st to 15thDay
5%11%7%12%7%5%7%5%6%6%25%
1236
16th to endDay
6%12%6%10%8%48%5%7%8%21%
1197
January1st to 15thNight
8%13%6%12%10%47%5%47%19%
2686
16th to endNight
6%12%5%10%8%47%5%6%8%22%
2697
February1st to 15thNight
8%15%6%10%7%35%5%6%6%24%
2356
16th to endNight
410%5%10%7%46%6%6%8%30%
1996
March1st to 15thNight
410%5%8%8%47%6%6%8%27%
2139
16th to endNight
39%5%9%9%5%8%6%6%7%26%
2013
April1st to 15thNight
49%410%8%47%5%7%7%29%
1799
16th to endNight
412%5%10%8%35%6%6%6%31%
1557
May1st to 15thNight
8%11%46%5%45%5%5%6%35%
1439
16th to endNight
12%8%38%7%35%6%5%8%30%
1496
June1st to 15thNight
14%7%36%7%35%5%6%9%30%
1098
16th to endNight
9%6%37%6%346%5%7%38%
1080
July1st to 15thNight
5%424425%5%6%7%50%
1242
16th to endNight
6%3234235%6%7%54%
1467
August1st to 15thNight
5%31332447%7%55%
1440
16th to endNight
6%5%35%5%345%5%7%47%
1765
September1st to 15thNight
6%5%15%324447%55%
1800
16th to endNight
9%6%35%5%3435%8%43%
1883
October1st to 15thNight
8%8%37%6%345%5%6%40%
1980
16th to endNight
9%10%48%6%35%6%6%7%30%
2249
November1st to 15thNight
9%12%48%7%47%6%6%6%25%
2427
16th to endNight
7%15%7%9%9%46%5%46%22%
2562
December1st to 15thNight
6%13%6%10%9%46%6%5%6%24%
2721
16th to endNight
6%12%6%10%9%5%6%6%6%6%22%
3036

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
5%11%5%14%10%5%7%7%6%6%20%
1253
16th to endDay
6%13%6%10%7%45%5%9%7%24%
1527
February1st to 15thDay
8%15%6%8%8%46%6%5%6%22%
1495
16th to endDay
5%12%7%10%9%35%7%5%7%25%
1478
March1st to 15thDay
5%13%7%11%9%46%6%6%6%19%
1821
16th to endDay
6%12%6%10%9%5%7%6%7%7%19%
2206
April1st to 15thDay
9%13%5%11%9%5%7%6%5%6%18%
2149
16th to endDay
9%15%5%10%9%46%6%6%7%20%
2400
May1st to 15thDay
10%12%5%8%8%45%5%5%6%27%
2511
16th to endDay
16%11%48%7%46%6%5%7%21%
2615
June1st to 15thDay
19%9%5%7%6%45%5%6%6%22%
2858
16th to endDay
13%7%48%7%46%5%5%7%29%
2880
July1st to 15thDay
7%5%25%5%35%6%6%8%44%
2714
16th to endDay
7%425%5%3445%7%49%
2702
August1st to 15thDay
6%425%5%35%5%6%8%48%
2520
16th to endDay
7%5%26%5%35%46%7%44%
2436
September1st to 15thDay
8%7%26%423346%49%
2160
16th to endDay
14%8%35%6%36%46%7%34%
1935
October1st to 15thDay
10%8%37%6%35%5%5%7%36%
1650
16th to endDay
10%12%47%7%46%5%6%8%27%
1622
November1st to 15thDay
11%12%5%10%7%45%45%6%25%
1430
16th to endDay
7%15%6%8%8%46%6%6%7%22%
1385
December1st to 15thDay
5%13%6%13%7%46%5%5%6%26%
1236
16th to endDay
6%12%6%9%8%5%7%6%7%7%22%
1197
January1st to 15thNight
7%14%7%11%9%5%5%5%6%7%17%
2685
16th to endNight
6%12%5%10%8%47%5%7%8%21%
2697
February1st to 15thNight
8%14%6%9%8%446%5%7%25%
2356
16th to endNight
410%5%9%6%46%5%5%8%32%
1996
March1st to 15thNight
410%5%8%9%47%6%7%7%28%
2139
16th to endNight
311%49%8%5%7%6%7%7%27%
2017
April1st to 15thNight
5%10%5%9%8%46%6%6%7%30%
1799
16th to endNight
5%11%5%9%7%46%6%5%6%31%
1557
May1st to 15thNight
7%11%47%6%35%5%5%5%36%
1439
16th to endNight
12%7%38%7%36%5%6%8%29%
1496
June1st to 15thNight
14%5%48%6%245%8%8%29%
1098
16th to endNight
10%5%38%6%35%45%6%39%
1080
July1st to 15thNight
6%323425%6%6%7%51%
1242
16th to endNight
6%3133245%6%7%55%
1467
August1st to 15thNight
5%42242346%7%55%
1440
16th to endNight
6%5%25%5%4445%8%47%
1765
September1st to 15thNight
6%42432435%6%55%
1800
16th to endNight
9%6%35%43345%8%44%
1883
October1st to 15thNight
8%7%37%5%35%35%7%41%
1980
16th to endNight
10%8%47%7%35%5%7%7%32%
2249
November1st to 15thNight
10%11%47%8%47%6%5%5%27%
2427
16th to endNight
8%14%7%10%9%46%5%47%21%
2562
December1st to 15thNight
6%13%7%10%8%46%5%5%6%24%
2721
16th to endNight
6%13%6%10%8%5%7%6%5%5%22%
3036

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%9%14%11%2
1253
16th to endDay
52%7%17%16%31
1527
February1st to 15thDay
59%7%15%13%3
1495
16th to endDay
54%5%15%15%8%
1478
March1st to 15thDay
61%7%15%12%3
1821
16th to endDay
60%5%15%14%2
2206
April1st to 15thDay
64%6%10%14%3
2149
16th to endDay
59%6%14%13%5%
2400
May1st to 15thDay
55%412%17%9%
2511
16th to endDay
60%5%14%15%4
2619
June1st to 15thDay
59%411%14%7%1
2858
16th to endDay
52%5%13%17%9%
2880
July1st to 15thDay
36%5%12%23%18%3
2555
16th to endDay
33%412%30%15%2
2534
August1st to 15thDay
32%5%15%29%13%3
2503
16th to endDay
37%415%28%12%2
2436
September1st to 15thDay
36%313%28%16%1
2160
16th to endDay
47%6%14%20%8%2
1935
October1st to 15thDay
46%418%25%6%
1650
16th to endDay
53%7%18%16%3
1622
November1st to 15thDay
58%6%11%17%4
1430
16th to endDay
57%7%13%16%5%
1385
December1st to 15thDay
57%8%15%15%3
1236
16th to endDay
57%8%14%14%3
1197
January1st to 15thNight
63%6%14%12%2
2686
16th to endNight
56%7%15%14%31
2697
February1st to 15thNight
56%6%15%16%4
2368
16th to endNight
48%419%18%7%
1996
March1st to 15thNight
50%8%17%18%5%
2139
16th to endNight
51%8%18%17%4
2017
April1st to 15thNight
50%7%15%19%6%
1799
16th to endNight
50%5%16%21%6%
1557
May1st to 15thNight
47%5%13%19%12%1
1440
16th to endNight
50%6%18%18%6%
1496
June1st to 15thNight
47%5%15%22%7%1
1098
16th to endNight
43%417%22%10%1
1080
July1st to 15thNight
29%5%13%29%19%3
1172
16th to endNight
24%5%14%32%18%3
1372
August1st to 15thNight
25%418%29%18%3
1432
16th to endNight
33%5%15%27%14%2
1765
September1st to 15thNight
28%315%31%17%3
1800
16th to endNight
37%5%16%25%11%3
1883
October1st to 15thNight
41%5%17%25%9%
1980
16th to endNight
48%6%18%22%3
2249
November1st to 15thNight
55%7%14%15%5%
2427
16th to endNight
61%6%13%12%6%
2562
December1st to 15thNight
58%6%14%16%3
2721
16th to endNight
60%8%13%13%3
3036

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
36%15%31%30%13%
60
16th to endDay
6%20%32%26%12%1
64
February1st to 15thDay
18%20%27%23%9%1
155
16th to endDay
10%23%28%19%15%1
221
March1st to 15thDay
28%28%26%11%4
270
16th to endDay
21%29%30%14%3
288
April1st to 15thDay
24%19%28%17%8%1
269
16th to endDay
20%26%30%16%41
270
May1st to 15thDay
24%15%24%23%8%3
288
16th to endDay
20%15%16%25%17%4
330
June1st to 15thDay
24%12%22%23%15%2
653
16th to endDay
17%12%28%24%14%3
675
July1st to 15thDay
11%17%25%28%14%2
489
16th to endDay
10%10%25%33%16%4
371
August1st to 15thDay
7%7%22%30%23%7%
315
16th to endDay
10%14%30%26%13%3
332
September1st to 15thDay
14%16%23%24%18%3
315
16th to endDay
21%16%29%18%10%3
288
October1st to 15thDay
22%20%24%19%10%1
255
16th to endDay
14%16%17%31%17%1
134
November1st to 15thDay
23%28%29%12%6%
64
16th to endDay
13%18%26%11%18%11%
60
December1st to 15thDay
8%25%25%13%21%6%
60
16th to endDay
7%21%31%20%10%7%
64
January1st to 15thNight
18%16%22%26%14%2
750
16th to endNight
11%13%25%29%16%2
769
February1st to 15thNight
15%13%17%34%15%3
704
16th to endNight
8%16%25%25%21%2
632
March1st to 15thNight
13%25%26%22%9%2
720
16th to endNight
11%24%26%22%11%3
768
April1st to 15thNight
11%17%23%26%17%3
719
16th to endNight
9%17%31%27%12%1
477
May1st to 15thNight
10%14%24%33%13%3
360
16th to endNight
16%6%23%27%23%3
375
June1st to 15thNight
14%11%26%30%13%4
360
16th to endNight
10%11%32%27%15%2
360
July1st to 15thNight
7%7%25%37%20%1
340
16th to endNight
8%322%37%25%2
376
August1st to 15thNight
7%314%31%35%7%
360
16th to endNight
10%7%21%29%26%4
619
September1st to 15thNight
9%7%17%25%29%10%
720
16th to endNight
13%14%19%23%22%5%
692
October1st to 15thNight
10%14%23%27%19%3
660
16th to endNight
15%16%25%22%16%3
704
November1st to 15thNight
19%20%27%24%7%1
700
16th to endNight
17%18%22%25%13%3
762
December1st to 15thNight
13%15%24%30%14%1
903
16th to endNight
12%19%26%28%10%1
956
Page generated at 2017-09-25 06:02:25. Version ac04

Copyright 2017 A. Danko


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