Prince George
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Prince George clear sky chart from 2005-11-05 to 2017-08-12.

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
40%
14690
7%
46378
5%
14660
42%
14660
13%
35714

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%
815
4%
2751
3%
811
27%
811
5%
2393
January16th to endNight
28%
800
8%
2880
8%
800
30%
800
8%
2337
February1st to 15thNight
32%
703
5%
2399
5%
702
34%
702
9%
1937
February16th to endNight
42%
632
9%
2053
8%
632
45%
632
15%
1532
March1st to 15thNight
30%
720
10%
2113
7%
720
33%
720
12%
1676
March16th to endNight
46%
768
9%
2051
5%
767
47%
767
15%
1603
April1st to 15thNight
43%
665
8%
1745
5%
665
44%
665
16%
1370
April16th to endNight
39%
426
7%
1506
7%
426
42%
426
10%
1161
May1st to 15thNight
47%
359
4%
1425
4%
359
48%
359
12%
1034
May16th to endNight
49%
374
0%
1218
0%
374
49%
374
16%
889
June1st to 15thNight
48%
360
0%
1080
0%
360
48%
360
16%
800
June16th to endNight
52%
360
0%
1080
0%
360
52%
360
17%
801
July1st to 15thNight
55%
340
0%
1062
0%
340
55%
340
19%
743
July16th to endNight
61%
376
3%
1239
1%
354
64%
354
25%
757
August1st to 15thNight
70%
352
10%
1359
13%
350
72%
350
26%
768
August16th to endNight
57%
493
10%
1543
10%
493
58%
493
18%
1095
September1st to 15thNight
62%
658
14%
1648
9%
658
63%
658
31%
1109
September16th to endNight
46%
656
13%
1809
8%
656
48%
656
18%
1354
October1st to 15thNight
45%
660
9%
1980
6%
660
49%
660
18%
1438
October16th to endNight
31%
704
7%
2323
4%
704
37%
704
10%
1834
November1st to 15thNight
29%
700
6%
2450
5%
700
32%
700
8%
1955
November16th to endNight
30%
847
7%
2712
5%
847
33%
847
10%
2178
December1st to 15thNight
30%
930
6%
2880
5%
930
32%
930
9%
2367
December16th to endNight
27%
992
7%
3072
3%
992
30%
992
8%
2583

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
12%9%47%7%46%5%6%7%28%
47645
Night
13%12%48%7%35%5%5%6%26%
46519
TransparencyDay
53%10%16%16%4
47286
Night
57%8%13%14%4
46382
SeeingDay
14%9%25%26%20%3
6702
Night
19%8%19%29%19%2
14697

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
15%18%8%10%7%5%6%5%5%413%
1197
16th to endDay
13%15%7%12%7%46%5%5%417%
1344
February1st to 15thDay
18%13%38%7%45%46%5%21%
1465
16th to endDay
8%13%39%9%35%45%6%28%
1421
March1st to 15thDay
11%16%5%7%6%45%5%5%6%23%
1845
16th to endDay
8%10%48%8%47%6%6%8%26%
2169
April1st to 15thDay
9%12%5%10%8%47%6%6%7%22%
2202
16th to endDay
15%11%6%8%8%45%45%6%22%
2453
May1st to 15thDay
11%9%5%8%7%36%5%6%6%28%
2525
16th to endDay
10%8%47%8%5%7%6%6%8%27%
2894
June1st to 15thDay
13%7%36%7%47%6%6%7%31%
2880
16th to endDay
12%6%37%7%5%6%6%6%7%29%
2880
July1st to 15thDay
11%7%345%36%7%6%8%34%
2834
16th to endDay
9%425%435%6%7%9%40%
2846
August1st to 15thDay
5%415%5%45%6%7%9%44%
2509
16th to endDay
11%6%37%6%45%6%7%7%33%
2306
September1st to 15thDay
8%6%25%5%345%6%7%44%
1981
16th to endDay
15%7%36%7%35%5%5%7%30%
1819
October1st to 15thDay
16%9%28%7%46%5%5%7%26%
1650
16th to endDay
18%12%47%6%45%6%47%23%
1549
November1st to 15thDay
18%12%5%8%7%35%5%5%5%21%
1408
16th to endDay
13%16%6%9%10%46%7%4416%
1236
December1st to 15thDay
15%14%5%10%9%35%6%5%5%18%
1080
16th to endDay
9%21%7%8%8%46%5%5%6%16%
1152
January1st to 15thNight
16%18%7%11%7%45%5%4414%
2751
16th to endNight
17%16%5%8%7%35%445%20%
2880
February1st to 15thNight
17%16%5%8%8%34445%21%
2387
16th to endNight
9%11%5%10%8%35%5%5%7%28%
2053
March1st to 15thNight
10%14%6%10%7%37%445%24%
2113
16th to endNight
8%11%47%8%47%6%7%7%25%
2051
April1st to 15thNight
11%12%6%7%7%46%5%6%7%26%
1745
16th to endNight
13%10%48%7%38%5%6%6%24%
1506
May1st to 15thNight
12%10%47%6%37%5%6%7%28%
1424
16th to endNight
11%7%47%7%46%7%8%8%27%
1218
June1st to 15thNight
14%7%46%6%48%5%7%8%27%
1080
16th to endNight
11%6%38%7%47%6%7%8%27%
1080
July1st to 15thNight
11%6%26%7%45%6%7%8%33%
1125
16th to endNight
9%4344345%6%7%44%
1323
August1st to 15thNight
7%3245%345%6%8%49%
1366
16th to endNight
12%6%36%5%46%6%6%7%34%
1543
September1st to 15thNight
8%5%35%6%3345%7%45%
1648
16th to endNight
14%9%47%4345%5%7%32%
1809
October1st to 15thNight
15%9%36%6%35%36%7%33%
1980
16th to endNight
18%12%48%6%35%5%5%7%22%
2323
November1st to 15thNight
16%14%46%7%46%6%6%5%22%
2450
16th to endNight
13%16%5%8%6%35%5%5%6%21%
2712
December1st to 15thNight
17%16%5%7%7%45%44422%
2880
16th to endNight
10%17%6%11%8%5%6%5%5%6%17%
3072

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
72%8%11%5%1
1197
16th to endDay
67%8%10%8%5%
1344
February1st to 15thDay
61%10%13%10%4
1465
16th to endDay
54%8%13%16%6%
1421
March1st to 15thDay
60%7%11%14%5%
1845
16th to endDay
55%8%18%14%3
2169
April1st to 15thDay
59%10%11%15%3
2202
16th to endDay
62%8%11%14%3
2453
May1st to 15thDay
54%8%14%16%6%
2525
16th to endDay
52%11%15%16%3
2898
June1st to 15thDay
51%10%13%18%6%
2880
16th to endDay
49%11%15%18%4
2880
July1st to 15thDay
45%9%17%19%7%
2668
16th to endDay
35%11%25%23%4
2667
August1st to 15thDay
33%12%25%24%4
2491
16th to endDay
47%9%19%19%3
2306
September1st to 15thDay
38%10%24%21%4
1981
16th to endDay
51%10%15%19%3
1819
October1st to 15thDay
53%10%19%14%2
1650
16th to endDay
59%11%17%10%1
1549
November1st to 15thDay
62%9%12%10%5%
1408
16th to endDay
67%9%10%11%1
1236
December1st to 15thDay
64%10%11%11%2
1080
16th to endDay
67%9%12%8%1
1152
January1st to 15thNight
73%8%9%7%1
2751
16th to endNight
65%7%11%8%5%
2880
February1st to 15thNight
65%6%12%9%5%
2399
16th to endNight
54%7%16%14%6%
2053
March1st to 15thNight
60%8%9%14%5%
2113
16th to endNight
54%10%16%13%4
2055
April1st to 15thNight
56%8%11%17%5%
1745
16th to endNight
59%8%12%12%6%
1506
May1st to 15thNight
54%8%10%16%9%
1425
16th to endNight
50%9%14%21%3
1218
June1st to 15thNight
52%8%11%19%6%
1080
16th to endNight
50%11%17%17%3
1080
July1st to 15thNight
47%8%14%17%11%1
1062
16th to endNight
35%10%24%26%4
1239
August1st to 15thNight
32%9%19%31%7%
1359
16th to endNight
46%11%18%18%4
1543
September1st to 15thNight
37%8%19%25%8%
1648
16th to endNight
50%9%13%20%6%
1809
October1st to 15thNight
50%8%20%17%3
1980
16th to endNight
59%10%15%13%1
2323
November1st to 15thNight
62%9%14%9%4
2450
16th to endNight
61%9%12%13%3
2712
December1st to 15thNight
63%9%11%12%2
2880
16th to endNight
67%8%10%10%2
3072

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
11%5%16%23%35%8%
60
16th to endDay
21%9%20%17%23%7%
64
February1st to 15thDay
24%12%28%17%12%4
146
16th to endDay
15%10%25%27%15%5%
211
March1st to 15thDay
17%18%37%19%6%
267
16th to endDay
12%18%30%26%10%1
288
April1st to 15thDay
18%15%30%21%11%2
269
16th to endDay
20%14%31%24%8%
270
May1st to 15thDay
14%13%29%27%12%2
302
16th to endDay
13%7%22%28%23%4
608
June1st to 15thDay
16%8%23%26%22%3
675
16th to endDay
12%5%24%28%23%5%
675
July1st to 15thDay
14%7%18%29%24%5%
602
16th to endDay
9%7%20%30%27%3
515
August1st to 15thDay
5%218%33%30%8%
342
16th to endDay
13%8%28%29%19%
268
September1st to 15thDay
12%7%26%28%22%2
255
16th to endDay
16%12%31%22%14%1
255
October1st to 15thDay
21%9%21%25%18%3
255
16th to endDay
23%9%25%19%18%2
131
November1st to 15thDay
30%10%35%13%8%3
60
16th to endDay
18%328%21%20%8%
60
December1st to 15thDay
16%6%16%20%31%8%
60
16th to endDay
18%6%10%32%21%9%
64
January1st to 15thNight
25%12%22%24%12%2
816
16th to endNight
25%13%22%24%13%1
800
February1st to 15thNight
26%11%16%26%16%2
707
16th to endNight
14%8%19%33%21%3
632
March1st to 15thNight
20%11%28%27%10%2
720
16th to endNight
14%7%18%31%23%3
768
April1st to 15thNight
17%6%18%31%20%4
665
16th to endNight
17%8%22%32%16%2
426
May1st to 15thNight
15%8%20%32%20%4
360
16th to endNight
14%320%32%25%4
375
June1st to 15thNight
15%5%18%31%25%3
360
16th to endNight
13%218%35%26%3
360
July1st to 15thNight
14%313%32%31%4
340
16th to endNight
9%216%35%31%5%
376
August1st to 15thNight
9%19%27%42%9%
352
16th to endNight
17%311%31%32%3
493
September1st to 15thNight
11%412%34%34%3
658
16th to endNight
18%7%18%30%19%4
656
October1st to 15thNight
21%6%18%32%18%2
660
16th to endNight
25%11%21%27%13%1
704
November1st to 15thNight
25%14%23%26%8%2
700
16th to endNight
24%12%23%28%9%2
847
December1st to 15thNight
26%10%20%26%15%1
930
16th to endNight
20%12%22%27%13%2
992
Page generated at 2017-08-13 11:16:54. Version ac04

Copyright 2017 A. Danko


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