Glennifer Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Glennifer Lake clear sky chart from 2005-11-05 to 2017-09-18.

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%
15155
11%
46801
8%
15128
47%
15128
19%
32963

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
36%
895
10%
2685
8%
895
38%
895
13%
2077
January16th to endNight
39%
841
17%
2761
13%
841
45%
841
17%
1922
February1st to 15thNight
40%
700
11%
2436
10%
698
43%
698
15%
1725
February16th to endNight
45%
632
12%
1983
12%
632
48%
632
18%
1418
March1st to 15thNight
39%
720
13%
2124
8%
720
44%
720
19%
1569
March16th to endNight
38%
768
11%
2074
5%
767
41%
767
18%
1585
April1st to 15thNight
37%
625
10%
1705
5%
625
41%
625
17%
1284
April16th to endNight
37%
540
10%
1620
8%
540
40%
540
18%
1179
May1st to 15thNight
43%
389
8%
1368
8%
389
46%
389
18%
919
May16th to endNight
44%
374
3%
1309
1%
374
45%
374
17%
929
June1st to 15thNight
45%
360
0%
1260
0%
360
45%
360
13%
950
June16th to endNight
51%
360
0%
1260
0%
360
51%
360
17%
876
July1st to 15thNight
60%
340
0%
1190
0%
340
60%
340
22%
779
July16th to endNight
63%
376
5%
1258
4%
354
64%
354
25%
749
August1st to 15thNight
64%
377
6%
1449
11%
375
64%
375
22%
893
August16th to endNight
61%
573
16%
1719
14%
573
64%
573
32%
1050
September1st to 15thNight
56%
660
16%
1799
11%
660
57%
660
31%
1155
September16th to endNight
54%
667
19%
1847
12%
667
58%
667
34%
1154
October1st to 15thNight
46%
660
14%
1959
9%
660
51%
660
21%
1355
October16th to endNight
45%
704
14%
2288
10%
704
51%
704
20%
1551
November1st to 15thNight
38%
834
16%
2427
11%
834
43%
834
21%
1720
November16th to endNight
33%
900
11%
2700
7%
900
37%
900
17%
1974
December1st to 15thNight
36%
900
11%
2700
9%
900
38%
900
15%
2051
December16th to endNight
39%
960
14%
2880
9%
960
43%
960
18%
2099

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%9%47%6%35%5%6%8%32%
48029
Night
8%10%47%6%35%5%6%8%32%
46954
TransparencyDay
47%9%17%18%6%
47681
Night
47%8%15%19%7%1
46806
SeeingDay
15%5%25%31%17%5%
6049
Night
12%426%37%16%1
15166

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
7%15%5%8%6%3435%7%31%
1253
16th to endDay
7%12%5%8%6%36%5%5%8%30%
1473
February1st to 15thDay
7%12%5%8%6%37%46%7%28%
1426
16th to endDay
5%10%7%9%7%36%8%6%7%26%
1491
March1st to 15thDay
5%11%5%10%9%45%5%5%7%28%
1835
16th to endDay
9%13%6%9%5%35%46%8%25%
2144
April1st to 15thDay
11%13%5%8%8%35%5%6%7%24%
2242
16th to endDay
14%12%47%6%35%45%7%28%
2340
May1st to 15thDay
10%9%36%6%36%6%6%7%33%
2581
16th to endDay
19%7%36%5%35%5%7%8%27%
2802
June1st to 15thDay
18%7%46%6%46%6%6%7%25%
2700
16th to endDay
14%6%36%7%46%7%7%8%29%
2700
July1st to 15thDay
11%5%25%435%7%7%10%35%
2700
16th to endDay
9%424425%5%7%10%41%
2825
August1st to 15thDay
13%5%244246%6%10%38%
2502
16th to endDay
9%4235%35%6%7%8%43%
2483
September1st to 15thDay
15%6%2442345%6%44%
2157
16th to endDay
9%6%24435%5%5%9%43%
1838
October1st to 15thDay
14%9%36%435%5%5%8%33%
1670
16th to endDay
9%8%47%5%45%46%7%36%
1584
November1st to 15thDay
6%12%6%8%7%35%5%5%6%31%
1419
16th to endDay
7%12%6%8%7%35%5%5%7%31%
1260
December1st to 15thDay
6%14%5%11%10%46%5%37%24%
1260
16th to endDay
411%6%11%7%35%6%6%7%29%
1344
January1st to 15thNight
6%12%7%10%9%47%5%5%6%24%
2685
16th to endNight
5%13%5%8%6%45%5%6%8%30%
2761
February1st to 15thNight
7%11%5%10%7%36%5%5%8%28%
2427
16th to endNight
5%11%6%9%7%47%45%6%30%
1983
March1st to 15thNight
5%11%47%8%37%6%6%10%27%
2124
16th to endNight
6%11%7%9%7%46%6%6%8%25%
2074
April1st to 15thNight
11%11%5%7%5%45%5%6%7%28%
1705
16th to endNight
13%12%38%5%3445%7%30%
1620
May1st to 15thNight
11%8%36%6%35%5%5%8%34%
1367
16th to endNight
20%7%25%5%245%8%7%29%
1309
June1st to 15thNight
16%9%36%5%5%6%5%7%7%25%
1260
16th to endNight
12%6%35%6%446%7%9%31%
1260
July1st to 15thNight
8%436%45%6%6%8%8%38%
1260
16th to endNight
8%314427%5%7%10%44%
1343
August1st to 15thNight
9%5%246%35%6%7%8%40%
1457
16th to endNight
8%5%25%435%45%9%46%
1719
September1st to 15thNight
12%6%2442345%6%46%
1799
16th to endNight
10%5%24325%37%7%47%
1847
October1st to 15thNight
11%7%37%6%35%5%5%7%35%
1959
16th to endNight
8%9%37%6%345%6%9%35%
2288
November1st to 15thNight
7%10%47%6%36%6%6%8%33%
2427
16th to endNight
5%12%6%11%7%345%5%7%29%
2700
December1st to 15thNight
6%13%7%9%7%5%6%447%27%
2700
16th to endNight
313%5%10%8%35%5%6%8%29%
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
52%6%12%20%6%1
1253
16th to endDay
51%7%14%14%9%2
1473
February1st to 15thDay
51%8%14%16%6%2
1426
16th to endDay
53%8%13%17%6%
1491
March1st to 15thDay
54%7%16%15%5%
1835
16th to endDay
55%7%15%16%4
2145
April1st to 15thDay
55%9%15%14%4
2242
16th to endDay
53%7%14%17%6%1
2340
May1st to 15thDay
46%7%15%19%10%
2581
16th to endDay
51%10%17%15%5%
2807
June1st to 15thDay
54%10%13%17%3
2700
16th to endDay
47%12%17%19%2
2700
July1st to 15thDay
40%11%24%19%3
2541
16th to endDay
35%12%23%23%4
2647
August1st to 15thDay
37%13%24%20%4
2485
16th to endDay
33%11%22%24%7%1
2483
September1st to 15thDay
39%6%19%20%11%2
2157
16th to endDay
36%8%15%26%10%2
1838
October1st to 15thDay
47%8%17%18%8%
1670
16th to endDay
46%6%15%23%7%
1584
November1st to 15thDay
50%9%13%17%7%
1419
16th to endDay
52%7%15%15%7%2
1260
December1st to 15thDay
60%6%13%14%4
1260
16th to endDay
51%7%14%16%8%1
1344
January1st to 15thNight
57%8%11%14%5%2
2685
16th to endNight
49%6%12%18%9%3
2761
February1st to 15thNight
52%6%14%18%7%1
2438
16th to endNight
51%6%13%16%11%1
1983
March1st to 15thNight
49%9%16%18%6%
2124
16th to endNight
54%7%13%17%5%1
2077
April1st to 15thNight
53%8%14%15%7%
1705
16th to endNight
52%6%14%19%5%1
1620
May1st to 15thNight
46%8%16%18%10%
1368
16th to endNight
49%9%18%15%6%1
1309
June1st to 15thNight
54%10%12%17%4
1260
16th to endNight
45%11%18%18%41
1260
July1st to 15thNight
38%12%22%22%3
1190
16th to endNight
33%10%23%23%8%
1258
August1st to 15thNight
37%10%26%20%5%
1449
16th to endNight
33%8%19%27%9%1
1719
September1st to 15thNight
35%8%16%23%12%3
1799
16th to endNight
33%7%16%26%12%3
1847
October1st to 15thNight
44%9%16%19%8%1
1959
16th to endNight
43%10%18%21%6%
2288
November1st to 15thNight
46%8%13%20%9%1
2427
16th to endNight
52%7%15%14%6%2
2700
December1st to 15thNight
56%6%13%17%4
2700
16th to endNight
51%7%13%19%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
15%116%33%20%13%
60
16th to endDay
15%18%26%26%12%
64
February1st to 15thDay
12%9%20%33%15%9%
65
16th to endDay
10%424%36%20%4
150
March1st to 15thDay
10%6%37%33%10%1
270
16th to endDay
15%5%33%28%13%2
288
April1st to 15thDay
18%9%33%25%11%
269
16th to endDay
22%7%30%24%11%2
270
May1st to 15thDay
13%6%26%28%18%5%
390
16th to endDay
19%6%17%32%19%4
517
June1st to 15thDay
20%423%33%15%2
495
16th to endDay
13%425%32%16%6%
495
July1st to 15thDay
14%220%32%24%6%
475
16th to endDay
9%5%23%33%22%6%
494
August1st to 15thDay
13%422%28%21%9%
315
16th to endDay
9%425%34%21%4
332
September1st to 15thDay
23%421%27%16%5%
315
16th to endDay
10%8%30%30%12%7%
264
October1st to 15thDay
21%7%30%25%12%3
154
16th to endDay
17%123%31%22%3
96
November1st to 15thDay
18%24%41%12%3
87
16th to endDay
11%5%23%30%15%15%
60
December1st to 15thDay
15%36%18%25%5%
60
16th to endDay
7%325%25%32%6%
64
January1st to 15thNight
14%6%28%35%13%1
900
16th to endNight
11%6%28%38%12%2
841
February1st to 15thNight
11%7%24%37%16%2
704
16th to endNight
9%326%37%20%3
632
March1st to 15thNight
9%332%39%13%2
720
16th to endNight
11%330%39%13%1
768
April1st to 15thNight
16%5%29%34%13%
625
16th to endNight
18%5%25%37%12%1
540
May1st to 15thNight
14%6%27%34%15%1
390
16th to endNight
20%420%35%18%
375
June1st to 15thNight
20%223%33%17%1
360
16th to endNight
14%122%36%22%2
360
July1st to 15thNight
11%114%46%24%1
340
16th to endNight
10%117%45%23%1
376
August1st to 15thNight
12%212%34%35%2
377
16th to endNight
10%118%45%23%
573
September1st to 15thNight
16%216%38%22%2
660
16th to endNight
12%225%37%18%2
667
October1st to 15thNight
15%324%38%16%1
660
16th to endNight
11%428%40%13%
704
November1st to 15thNight
12%6%33%33%11%2
834
16th to endNight
11%336%35%10%2
900
December1st to 15thNight
12%7%29%34%14%2
900
16th to endNight
10%329%37%16%3
960
Page generated at 2017-09-19 05:32:21. Version ac04

Copyright 2017 A. Danko


Glennifer Lake Clear Sky Chart | Charts Home