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 2018-02-22.

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%
15561
7%
48952
5%
15531
42%
15531
13%
37629

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
27%
896
4%
2982
3%
892
29%
892
6%
2573
January16th to endNight
28%
880
8%
3120
8%
880
31%
880
8%
2531
February1st to 15thNight
33%
764
7%
2601
6%
763
35%
763
9%
2090
February16th to endNight
43%
660
10%
2144
8%
660
47%
660
15%
1589
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%
1216
0%
374
49%
374
16%
887
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%
1060
0%
340
55%
340
19%
741
July16th to endNight
61%
376
3%
1239
1%
354
64%
354
25%
757
August1st to 15thNight
70%
360
10%
1391
13%
358
72%
358
26%
785
August16th to endNight
58%
538
10%
1684
11%
538
59%
538
19%
1190
September1st to 15thNight
62%
719
14%
1799
9%
719
63%
719
32%
1204
September16th to endNight
47%
716
14%
1974
9%
716
49%
716
19%
1474
October1st to 15thNight
44%
720
9%
2160
6%
720
48%
720
17%
1573
October16th to endNight
32%
768
8%
2535
5%
768
37%
768
10%
1986
November1st to 15thNight
30%
760
6%
2660
5%
760
33%
760
8%
2114
November16th to endNight
29%
924
7%
2939
4%
924
32%
924
10%
2386
December1st to 15thNight
33%
1020
6%
3120
5%
1020
34%
1020
10%
2539
December16th to endNight
30%
1088
8%
3328
4%
1088
33%
1088
9%
2765

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%10%47%7%46%5%6%7%28%
49346
Night
13%12%48%7%45%5%5%6%26%
49093
TransparencyDay
53%9%16%16%4
48987
Night
56%8%13%14%4
48956
SeeingDay
15%9%25%26%19%3
7245
Night
19%8%19%29%19%2
15568

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
14%17%8%10%8%6%6%5%4412%
1297
16th to endDay
13%15%7%11%7%46%5%5%416%
1456
February1st to 15thDay
17%13%38%7%45%46%6%21%
1591
16th to endDay
8%13%49%9%35%45%7%29%
1476
March1st to 15thDay
11%16%5%7%6%45%5%5%6%23%
1846
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%
2454
May1st to 15thDay
11%9%5%8%7%36%5%6%6%28%
2523
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%
2835
16th to endDay
9%425%435%6%7%9%40%
2846
August1st to 15thDay
5%415%6%45%6%7%9%44%
2562
16th to endDay
11%6%37%6%45%6%6%7%33%
2518
September1st to 15thDay
9%6%25%5%345%5%6%44%
2160
16th to endDay
15%7%37%8%35%5%5%7%30%
1985
October1st to 15thDay
16%10%28%6%45%45%7%27%
1800
16th to endDay
19%11%46%6%45%5%5%7%23%
1689
November1st to 15thDay
18%12%5%8%7%35%5%5%422%
1528
16th to endDay
12%16%6%10%10%46%7%4415%
1337
December1st to 15thDay
14%13%5%10%9%35%6%5%6%19%
1170
16th to endDay
8%20%7%8%8%47%5%5%6%16%
1248
January1st to 15thNight
15%17%7%11%7%45%5%4415%
2982
16th to endNight
16%16%5%8%7%46%445%20%
3120
February1st to 15thNight
17%16%5%8%7%34445%22%
2589
16th to endNight
8%11%5%9%7%35%5%5%7%29%
2144
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%
1216
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%
1123
16th to endNight
9%4344345%6%7%44%
1323
August1st to 15thNight
6%3245%345%6%8%49%
1398
16th to endNight
12%5%26%5%45%6%6%7%35%
1684
September1st to 15thNight
9%6%35%6%3345%7%45%
1799
16th to endNight
15%9%46%435%5%5%7%32%
1974
October1st to 15thNight
15%9%36%5%35%45%6%33%
2160
16th to endNight
18%12%47%6%35%5%5%7%23%
2535
November1st to 15thNight
16%13%46%7%46%6%6%5%22%
2660
16th to endNight
13%17%5%9%7%45%5%5%6%20%
2939
December1st to 15thNight
16%15%5%7%7%45%5%4423%
3120
16th to endNight
10%16%6%10%8%5%6%5%5%6%18%
3328

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%9%11%6%1
1297
16th to endDay
68%8%9%8%5%
1456
February1st to 15thDay
60%10%13%10%4
1591
16th to endDay
53%8%14%17%5%
1476
March1st to 15thDay
60%7%11%14%5%
1846
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
2454
May1st to 15thDay
54%8%14%16%6%
2523
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%
2669
16th to endDay
35%11%25%23%4
2667
August1st to 15thDay
33%11%25%23%4
2544
16th to endDay
47%10%19%18%3
2518
September1st to 15thDay
38%10%23%22%5%
2160
16th to endDay
52%10%14%19%3
1985
October1st to 15thDay
52%9%19%14%2
1800
16th to endDay
59%11%17%11%1
1689
November1st to 15thDay
62%8%11%10%6%
1528
16th to endDay
68%9%9%10%1
1337
December1st to 15thDay
62%10%12%11%2
1170
16th to endDay
66%9%11%8%3
1248
January1st to 15thNight
71%8%10%7%1
2982
16th to endNight
65%7%11%8%5%
3120
February1st to 15thNight
64%6%11%9%5%
2601
16th to endNight
54%8%16%14%6%
2144
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
1216
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
1060
16th to endNight
35%10%24%26%4
1239
August1st to 15thNight
31%9%18%31%8%
1391
16th to endNight
45%11%19%19%3
1684
September1st to 15thNight
37%7%18%27%8%
1799
16th to endNight
50%9%13%20%6%
1974
October1st to 15thNight
50%8%19%17%4
2160
16th to endNight
58%10%15%13%1
2535
November1st to 15thNight
62%9%13%10%4
2660
16th to endNight
62%9%12%12%3
2939
December1st to 15thNight
62%9%12%12%2
3120
16th to endNight
66%8%10%10%3
3328

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
10%5%11%31%32%10%
90
16th to endDay
25%7%23%18%19%5%
96
February1st to 15thDay
24%12%27%19%12%3
183
16th to endDay
14%10%29%26%13%5%
230
March1st to 15thDay
17%18%36%19%6%
268
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%28%12%3
300
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%
603
16th to endDay
9%7%20%30%27%3
515
August1st to 15thDay
5%319%33%30%8%
357
16th to endDay
13%8%29%29%18%1
332
September1st to 15thDay
14%8%24%26%22%3
315
16th to endDay
16%11%31%22%16%1
315
October1st to 15thDay
23%10%22%23%16%4
315
16th to endDay
23%12%24%20%17%1
175
November1st to 15thDay
24%12%31%15%12%4
90
16th to endDay
20%6%32%20%14%6%
90
December1st to 15thDay
13%413%26%32%10%
90
16th to endDay
13%415%38%19%8%
96
January1st to 15thNight
24%11%22%24%14%2
897
16th to endNight
23%12%23%25%13%1
880
February1st to 15thNight
27%10%16%27%16%1
768
16th to endNight
13%8%19%34%20%2
660
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
8%110%27%42%9%
360
16th to endNight
17%211%33%31%3
538
September1st to 15thNight
12%413%33%34%3
719
16th to endNight
19%7%17%30%21%4
716
October1st to 15thNight
22%5%18%30%17%3
720
16th to endNight
24%11%22%27%13%1
768
November1st to 15thNight
25%13%22%26%9%1
760
16th to endNight
24%12%23%27%9%2
924
December1st to 15thNight
24%9%19%27%16%1
1020
16th to endNight
19%11%22%30%14%2
1088
Page generated at 2018-02-23 08:21:30. Version ac04

Copyright 2018 A. Danko


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