La Loche
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the La Loche clear sky chart from 2005-11-05 to 2017-11-30.

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
35%
15641
9%
47383
5%
15615
39%
15615
17%
34646

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
24%
895
7%
2807
4%
895
28%
895
12%
2205
January16th to endNight
29%
960
11%
2880
7%
960
33%
960
15%
2176
February1st to 15thNight
36%
800
11%
2496
7%
798
41%
798
17%
1829
February16th to endNight
37%
632
12%
2052
9%
632
41%
632
15%
1518
March1st to 15thNight
31%
720
14%
2136
10%
720
35%
720
18%
1564
March16th to endNight
36%
735
13%
2079
8%
735
40%
735
18%
1533
April1st to 15thNight
39%
539
13%
1679
10%
539
43%
539
21%
1150
April16th to endNight
41%
540
13%
1506
8%
540
44%
540
24%
1029
May1st to 15thNight
43%
407
4%
1308
2%
407
44%
407
23%
862
May16th to endNight
51%
374
0%
1162
0%
374
51%
374
25%
753
June1st to 15thNight
47%
360
0%
1025
0%
360
47%
360
23%
718
June16th to endNight
53%
360
0%
900
0%
360
53%
360
26%
642
July1st to 15thNight
53%
340
0%
934
0%
340
53%
340
27%
624
July16th to endNight
61%
376
0%
1210
0%
354
62%
354
28%
716
August1st to 15thNight
57%
402
2%
1295
2%
400
58%
400
28%
802
August16th to endNight
48%
573
10%
1677
7%
573
51%
573
28%
1100
September1st to 15thNight
49%
540
12%
1746
8%
540
53%
540
27%
1072
September16th to endNight
40%
683
14%
1983
9%
683
45%
683
24%
1329
October1st to 15thNight
30%
720
10%
2160
5%
720
35%
720
17%
1571
October16th to endNight
23%
900
7%
2604
3%
900
26%
900
13%
2035
November1st to 15thNight
25%
950
12%
2680
6%
950
31%
950
14%
2082
November16th to endNight
25%
975
6%
3112
2%
975
29%
975
10%
2512
December1st to 15thNight
28%
900
4%
2880
2%
900
30%
900
8%
2427
December16th to endNight
30%
960
10%
3072
6%
960
35%
960
12%
2397

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%8%47%6%46%5%5%7%31%
49065
Night
11%11%48%7%45%5%5%7%28%
47526
TransparencyDay
51%5%16%20%6%
48701
Night
54%5%15%18%5%
47394
SeeingDay
15%7%26%28%17%4
6761
Night
16%6%26%31%16%3
15654

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
9%15%7%11%8%45%5%6%6%17%
1128
16th to endDay
8%12%5%10%9%5%7%5%5%6%23%
1344
February1st to 15thDay
6%8%48%7%5%9%7%6%9%24%
1365
16th to endDay
5%12%5%10%8%5%8%7%7%6%23%
1422
March1st to 15thDay
10%13%5%8%5%45%5%47%30%
1821
16th to endDay
9%8%49%7%36%46%7%31%
2144
April1st to 15thDay
10%10%46%7%46%5%6%7%31%
2269
16th to endDay
11%10%46%5%38%6%6%6%31%
2454
May1st to 15thDay
10%5%35%6%46%5%6%7%37%
2640
16th to endDay
14%5%25%5%35%5%6%6%38%
2949
June1st to 15thDay
15%5%25%7%46%6%6%8%30%
2933
16th to endDay
17%6%35%5%36%5%6%7%30%
3060
July1st to 15thDay
12%435%6%36%6%7%8%35%
2967
16th to endDay
12%5%36%5%36%6%7%8%35%
2876
August1st to 15thDay
12%425%5%46%5%5%8%40%
2658
16th to endDay
18%6%25%5%345%6%8%33%
2524
September1st to 15thDay
16%5%36%5%3445%6%39%
2214
16th to endDay
16%8%35%6%345%5%6%35%
1977
October1st to 15thDay
14%14%46%6%35%445%30%
1800
16th to endDay
14%21%6%6%5%14335%27%
1607
November1st to 15thDay
14%14%5%9%7%35%44424%
1508
16th to endDay
11%13%6%13%12%5%7%44415%
1173
December1st to 15thDay
8%15%8%13%12%5%7%5%45%13%
1080
16th to endDay
8%12%5%8%11%7%7%7%5%6%18%
1152
January1st to 15thNight
8%13%6%12%8%46%5%6%5%20%
2807
16th to endNight
8%13%6%9%7%47%6%6%7%24%
2880
February1st to 15thNight
5%10%49%9%5%8%7%6%7%25%
2496
16th to endNight
6%11%5%11%10%5%6%46%7%24%
2052
March1st to 15thNight
10%12%6%9%8%345%5%6%29%
2136
16th to endNight
10%13%5%8%6%35%45%6%30%
2076
April1st to 15thNight
12%8%47%6%35%45%7%33%
1679
16th to endNight
8%10%46%6%35%5%6%5%36%
1506
May1st to 15thNight
14%7%36%6%245%46%38%
1307
16th to endNight
14%5%345%346%5%8%38%
1162
June1st to 15thNight
16%447%5%36%46%8%31%
1025
16th to endNight
12%5%37%6%46%5%5%9%35%
900
July1st to 15thNight
8%5%346%47%5%7%9%37%
991
16th to endNight
8%324435%5%8%11%40%
1293
August1st to 15thNight
14%4145%25%48%9%38%
1302
16th to endNight
13%5%15%6%346%7%9%36%
1677
September1st to 15thNight
14%6%24434447%43%
1746
16th to endNight
15%6%25%5%345%5%8%36%
1983
October1st to 15thNight
17%14%36%5%2445%5%28%
2160
16th to endNight
16%18%5%7%6%24345%23%
2604
November1st to 15thNight
13%14%5%10%6%4444426%
2680
16th to endNight
11%12%5%11%10%47%5%5%5%19%
3112
December1st to 15thNight
9%15%7%11%9%5%7%7%5%5%14%
2880
16th to endNight
8%12%6%12%9%5%6%5%6%7%19%
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
64%5%11%15%3
1128
16th to endDay
59%5%15%14%41
1344
February1st to 15thDay
53%418%17%6%
1365
16th to endDay
58%415%14%7%
1422
March1st to 15thDay
53%417%21%3
1821
16th to endDay
50%5%12%27%4
2145
April1st to 15thDay
49%415%18%10%
2269
16th to endDay
50%49%24%10%
2454
May1st to 15thDay
43%411%26%13%
2640
16th to endDay
44%312%21%17%1
2954
June1st to 15thDay
50%412%22%9%
2933
16th to endDay
50%6%13%19%8%
3060
July1st to 15thDay
43%5%18%25%5%
2795
16th to endDay
44%6%25%21%2
2696
August1st to 15thDay
40%7%24%23%4
2640
16th to endDay
46%6%24%19%2
2524
September1st to 15thDay
44%422%21%6%
2214
16th to endDay
48%420%20%4
1977
October1st to 15thDay
56%418%17%3
1800
16th to endDay
60%415%17%1
1607
November1st to 15thDay
62%313%16%3
1508
16th to endDay
70%7%11%8%2
1173
December1st to 15thDay
72%5%9%10%1
1080
16th to endDay
63%6%13%14%2
1152
January1st to 15thNight
63%414%14%3
2807
16th to endNight
57%5%15%15%5%
2880
February1st to 15thNight
54%5%14%19%6%
2507
16th to endNight
58%414%17%5%
2052
March1st to 15thNight
55%313%22%4
2136
16th to endNight
54%5%10%23%5%
2079
April1st to 15thNight
49%312%21%11%1
1679
16th to endNight
46%39%24%12%2
1506
May1st to 15thNight
46%37%27%14%1
1308
16th to endNight
42%5%9%18%19%3
1162
June1st to 15thNight
49%312%22%11%
1025
16th to endNight
46%5%12%22%11%1
900
July1st to 15thNight
38%8%16%28%6%
934
16th to endNight
34%8%26%27%4
1210
August1st to 15thNight
38%6%28%22%5%
1295
16th to endNight
39%6%23%26%3
1677
September1st to 15thNight
39%421%26%7%
1746
16th to endNight
44%5%21%21%6%
1983
October1st to 15thNight
55%316%19%4
2160
16th to endNight
62%417%12%2
2604
November1st to 15thNight
61%411%18%3
2680
16th to endNight
64%7%14%11%1
3112
December1st to 15thNight
69%7%12%8%2
2880
16th to endNight
62%413%16%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
6%5%31%31%18%6%
60
16th to endDay
15%431%34%12%1
64
February1st to 15thDay
9%8%28%36%9%7%
71
16th to endDay
19%429%29%13%2
81
March1st to 15thDay
20%8%38%24%7%
180
16th to endDay
13%12%35%28%10%
288
April1st to 15thDay
15%11%30%32%8%1
269
16th to endDay
17%6%31%29%13%1
384
May1st to 15thDay
13%9%23%32%17%3
468
16th to endDay
15%5%20%29%24%5%
517
June1st to 15thDay
18%7%22%27%19%4
548
16th to endDay
16%5%22%28%20%6%
675
July1st to 15thDay
10%6%25%31%21%4
559
16th to endDay
13%323%32%20%6%
515
August1st to 15thDay
13%419%23%26%12%
493
16th to endDay
15%6%32%26%15%2
373
September1st to 15thDay
19%8%24%29%14%3
315
16th to endDay
18%13%26%24%13%3
279
October1st to 15thDay
22%7%31%20%13%3
135
16th to endDay
36%11%19%21%6%4
144
November1st to 15thDay
15%5%37%27%13%
130
16th to endDay
12%11%34%24%10%6%
89
December1st to 15thDay
15%336%18%20%6%
60
16th to endDay
14%331%32%14%4
64
January1st to 15thNight
13%8%30%29%14%3
900
16th to endNight
14%8%33%32%8%2
960
February1st to 15thNight
9%6%29%34%15%3
806
16th to endNight
9%6%23%39%17%3
632
March1st to 15thNight
15%7%32%30%13%1
720
16th to endNight
16%7%25%30%17%3
735
April1st to 15thNight
17%5%27%33%13%2
539
16th to endNight
12%6%27%34%17%1
540
May1st to 15thNight
18%7%21%30%20%1
408
16th to endNight
17%417%36%20%4
375
June1st to 15thNight
20%316%36%19%2
360
16th to endNight
15%315%33%27%5%
360
July1st to 15thNight
10%416%39%24%3
340
16th to endNight
9%215%38%23%10%
376
August1st to 15thNight
13%313%30%32%6%
402
16th to endNight
14%324%32%23%2
573
September1st to 15thNight
15%420%33%21%4
540
16th to endNight
19%7%26%30%14%2
683
October1st to 15thNight
23%6%29%25%12%3
720
16th to endNight
26%9%28%25%9%1
900
November1st to 15thNight
19%9%30%25%12%2
950
16th to endNight
17%8%33%27%10%1
975
December1st to 15thNight
16%6%28%32%14%3
900
16th to endNight
13%7%26%30%18%3
960
Page generated at 2017-12-01 11:13:34. Version ac04

Copyright 2017 A. Danko


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