Keivers Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Keivers Lake clear sky chart from 2005-11-05 to 2017-10-06.

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
43%
15270
12%
47000
9%
15244
47%
15244
21%
31924

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
35%
895
11%
2685
7%
895
38%
895
15%
2013
January16th to endNight
39%
852
17%
2772
11%
852
47%
852
19%
1894
February1st to 15thNight
41%
699
13%
2414
11%
697
45%
697
17%
1660
February16th to endNight
42%
632
13%
1998
13%
632
45%
632
20%
1385
March1st to 15thNight
39%
720
13%
2109
8%
720
44%
720
20%
1502
March16th to endNight
34%
767
10%
2097
4%
767
38%
767
17%
1602
April1st to 15thNight
37%
611
11%
1691
4%
611
41%
611
18%
1247
April16th to endNight
39%
540
13%
1620
10%
540
41%
540
22%
1115
May1st to 15thNight
43%
419
11%
1386
9%
419
47%
419
23%
889
May16th to endNight
44%
374
5%
1309
3%
374
46%
374
19%
883
June1st to 15thNight
42%
360
0%
1260
0%
360
42%
360
15%
895
June16th to endNight
46%
360
0%
1260
0%
360
46%
360
20%
827
July1st to 15thNight
61%
340
0%
1190
0%
340
61%
340
24%
735
July16th to endNight
63%
376
7%
1247
6%
354
64%
354
31%
692
August1st to 15thNight
61%
400
8%
1472
12%
398
62%
398
24%
866
August16th to endNight
63%
573
18%
1719
16%
573
65%
573
39%
943
September1st to 15thNight
55%
642
16%
1797
11%
642
57%
642
35%
1091
September16th to endNight
55%
716
20%
1980
14%
716
60%
716
37%
1202
October1st to 15thNight
46%
684
15%
2017
9%
684
52%
684
24%
1372
October16th to endNight
44%
704
16%
2288
11%
704
51%
704
24%
1483
November1st to 15thNight
37%
846
19%
2421
11%
846
45%
846
24%
1637
November16th to endNight
34%
900
12%
2688
8%
900
38%
900
19%
1919
December1st to 15thNight
35%
900
11%
2700
8%
900
38%
900
16%
2028
December16th to endNight
39%
960
15%
2880
10%
960
44%
960
19%
2044

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
11%8%36%6%35%5%6%8%33%
48238
Night
8%9%47%6%35%5%6%8%33%
47149
TransparencyDay
46%5%17%21%7%
47889
Night
47%5%15%21%8%1
47002
SeeingDay
14%6%22%31%19%5%
6127
Night
13%5%25%36%17%2
15283

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
8%13%5%7%6%35%6%6%7%29%
1253
16th to endDay
9%10%5%8%7%45%5%6%7%29%
1464
February1st to 15thDay
8%13%48%6%45%46%9%27%
1449
16th to endDay
6%13%6%9%8%45%6%6%7%24%
1476
March1st to 15thDay
6%12%5%9%9%36%6%6%8%25%
1851
16th to endDay
10%14%6%9%6%36%46%7%24%
2123
April1st to 15thDay
11%12%5%7%6%35%6%6%7%26%
2256
16th to endDay
15%10%46%5%35%45%8%29%
2340
May1st to 15thDay
12%8%25%5%36%5%5%9%35%
2564
16th to endDay
20%6%35%5%35%6%6%8%28%
2802
June1st to 15thDay
16%6%36%6%46%6%7%7%27%
2700
16th to endDay
12%5%35%6%46%6%7%8%32%
2700
July1st to 15thDay
10%5%145%35%6%6%10%39%
2700
16th to endDay
8%4243345%6%10%46%
2837
August1st to 15thDay
12%5%244345%7%8%41%
2479
16th to endDay
9%323435%6%6%9%47%
2483
September1st to 15thDay
14%5%25%423346%45%
2160
16th to endDay
10%6%145%3445%8%45%
1980
October1st to 15thDay
13%8%37%6%4445%6%35%
1739
16th to endDay
7%9%46%6%45%46%7%36%
1584
November1st to 15thDay
9%12%5%9%5%25%5%5%7%30%
1425
16th to endDay
7%12%410%6%46%5%5%5%31%
1269
December1st to 15thDay
7%14%6%10%10%6%6%345%23%
1260
16th to endDay
5%11%6%9%9%47%6%6%7%25%
1344
January1st to 15thNight
7%12%6%10%8%46%5%7%7%23%
2685
16th to endNight
6%13%5%8%5%45%5%6%7%31%
2772
February1st to 15thNight
6%10%5%10%7%45%5%5%8%29%
2403
16th to endNight
6%12%5%8%8%35%5%7%7%29%
1998
March1st to 15thNight
6%10%5%8%8%46%5%7%8%27%
2109
16th to endNight
9%14%6%8%7%36%6%6%7%23%
2096
April1st to 15thNight
11%10%5%7%7%35%5%5%9%27%
1691
16th to endNight
13%10%46%5%35%5%5%7%31%
1620
May1st to 15thNight
11%9%35%5%35%6%7%7%35%
1385
16th to endNight
19%7%245%445%5%8%32%
1309
June1st to 15thNight
16%6%47%6%47%6%7%6%27%
1260
16th to endNight
13%6%36%6%36%6%5%8%33%
1260
July1st to 15thNight
7%425%5%47%6%7%9%39%
1260
16th to endNight
6%3345%245%6%11%46%
1331
August1st to 15thNight
9%5%15%6%345%6%8%42%
1480
16th to endNight
7%3144235%5%10%49%
1719
September1st to 15thNight
12%5%2432335%7%48%
1797
16th to endNight
10%42432446%7%48%
1980
October1st to 15thNight
11%9%35%6%35%5%5%6%36%
2017
16th to endNight
8%9%47%5%345%6%8%36%
2288
November1st to 15thNight
8%9%46%6%45%5%5%9%34%
2421
16th to endNight
6%11%5%10%8%45%45%8%29%
2688
December1st to 15thNight
6%12%6%11%8%46%5%5%6%26%
2700
16th to endNight
410%5%11%7%46%6%5%7%28%
2880

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
51%5%13%21%6%1
1253
16th to endDay
51%414%16%9%3
1464
February1st to 15thDay
53%415%18%6%1
1449
16th to endDay
57%5%13%18%5%
1476
March1st to 15thDay
54%5%16%16%6%
1851
16th to endDay
57%5%12%19%5%
2124
April1st to 15thDay
52%6%14%18%6%
2256
16th to endDay
53%313%19%8%1
2340
May1st to 15thDay
44%315%24%11%
2564
16th to endDay
51%417%20%5%
2807
June1st to 15thDay
51%5%16%20%5%
2700
16th to endDay
45%6%19%24%4
2700
July1st to 15thDay
39%6%24%24%5%
2541
16th to endDay
32%6%26%26%7%
2658
August1st to 15thDay
37%7%26%23%5%
2462
16th to endDay
31%423%28%9%1
2483
September1st to 15thDay
39%316%24%12%3
2160
16th to endDay
36%5%15%28%11%2
1980
October1st to 15thDay
48%415%23%8%
1739
16th to endDay
44%415%25%8%
1584
November1st to 15thDay
52%413%20%6%1
1425
16th to endDay
51%417%17%7%1
1269
December1st to 15thDay
63%312%15%4
1260
16th to endDay
54%414%18%6%1
1344
January1st to 15thNight
57%5%12%16%5%2
2685
16th to endNight
49%413%19%9%3
2772
February1st to 15thNight
52%412%21%8%
2414
16th to endNight
50%413%18%11%
1998
March1st to 15thNight
50%5%17%20%5%
2109
16th to endNight
57%5%13%17%5%1
2099
April1st to 15thNight
53%5%14%16%9%
1691
16th to endNight
48%313%25%6%1
1620
May1st to 15thNight
44%414%24%11%1
1386
16th to endNight
49%417%20%7%1
1309
June1st to 15thNight
53%6%13%19%5%
1260
16th to endNight
46%5%19%21%5%
1260
July1st to 15thNight
37%9%23%24%5%
1190
16th to endNight
30%7%24%28%9%
1247
August1st to 15thNight
36%7%24%24%7%
1472
16th to endNight
28%420%32%11%2
1719
September1st to 15thNight
34%316%25%14%5%
1797
16th to endNight
33%417%26%14%3
1980
October1st to 15thNight
46%5%14%23%9%1
2017
16th to endNight
42%5%17%24%8%
2288
November1st to 15thNight
45%413%24%9%1
2421
16th to endNight
53%415%16%7%2
2688
December1st to 15thNight
57%413%19%3
2700
16th to endNight
53%313%21%6%
2880

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
16%118%30%21%11%
60
16th to endDay
7%126%25%25%14%
64
February1st to 15thDay
18%421%31%18%4
69
16th to endDay
18%5%17%34%22%1
135
March1st to 15thDay
10%6%32%35%11%2
270
16th to endDay
11%6%31%32%15%1
288
April1st to 15thDay
20%11%24%31%10%2
269
16th to endDay
21%7%25%27%12%4
270
May1st to 15thDay
13%8%22%26%22%5%
402
16th to endDay
22%417%29%21%5%
517
June1st to 15thDay
17%7%22%31%16%3
495
16th to endDay
10%6%23%33%21%5%
495
July1st to 15thDay
12%416%33%24%8%
475
16th to endDay
8%321%33%26%6%
506
August1st to 15thDay
13%216%31%25%9%
315
16th to endDay
10%424%31%21%7%
332
September1st to 15thDay
21%424%25%17%6%
315
16th to endDay
11%9%24%28%17%7%
315
October1st to 15thDay
18%9%16%31%17%5%
164
16th to endDay
15%416%34%26%3
96
November1st to 15thDay
18%5%28%37%44
90
16th to endDay
13%326%18%27%11%
61
December1st to 15thDay
13%331%28%18%5%
60
16th to endDay
9%126%29%26%6%
64
January1st to 15thNight
14%6%28%34%13%2
900
16th to endNight
12%5%28%35%14%2
852
February1st to 15thNight
10%9%22%34%20%2
704
16th to endNight
10%424%37%20%3
632
March1st to 15thNight
10%330%37%15%2
720
16th to endNight
13%5%25%38%14%1
768
April1st to 15thNight
17%6%26%31%15%2
611
16th to endNight
18%6%24%37%11%1
540
May1st to 15thNight
14%5%25%36%16%
420
16th to endNight
21%421%30%20%2
375
June1st to 15thNight
17%5%23%33%16%3
360
16th to endNight
15%321%33%22%1
360
July1st to 15thNight
9%118%42%27%1
340
16th to endNight
7%119%44%24%2
376
August1st to 15thNight
12%212%38%31%3
400
16th to endNight
9%217%42%27%1
573
September1st to 15thNight
15%318%37%23%2
642
16th to endNight
12%323%37%21%2
716
October1st to 15thNight
14%5%22%35%18%3
684
16th to endNight
13%326%40%14%1
704
November1st to 15thNight
11%7%32%35%10%2
846
16th to endNight
11%5%32%34%13%2
900
December1st to 15thNight
12%5%29%33%14%3
900
16th to endNight
10%427%38%15%4
960
Page generated at 2017-10-07 12:07:47. Version ac04

Copyright 2017 A. Danko


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