Knob Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Knob Lake clear sky chart from 2005-11-05 to 2018-01-20.

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
46%
13704
6%
48430
6%
13678
47%
13678
12%
36945

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
47%
864
7%
3483
7%
864
49%
864
13%
2462
January16th to endNight
45%
825
9%
3164
8%
825
46%
825
13%
2316
February1st to 15thNight
52%
732
11%
2621
10%
728
53%
728
20%
1754
February16th to endNight
46%
638
9%
2179
7%
638
48%
638
19%
1498
March1st to 15thNight
60%
570
13%
2160
14%
570
63%
570
20%
1389
March16th to endNight
58%
580
10%
2017
11%
580
58%
580
17%
1418
April1st to 15thNight
47%
539
4%
1647
3%
539
48%
539
13%
1279
April16th to endNight
57%
540
0%
1374
1%
540
57%
540
18%
1079
May1st to 15thNight
47%
410
0%
1131
0%
410
47%
410
12%
928
May16th to endNight
53%
195
0%
906
0%
195
53%
195
12%
629
June1st to 15thNight
46%
180
0%
720
0%
180
46%
180
7%
589
June16th to endNight
45%
180
0%
720
0%
180
45%
180
6%
596
July1st to 15thNight
40%
170
0%
680
0%
170
40%
170
6%
565
July16th to endNight
43%
295
0%
942
0%
275
43%
275
6%
813
August1st to 15thNight
43%
414
0%
1139
0%
412
42%
412
9%
976
August16th to endNight
33%
573
0%
1543
0%
573
34%
573
5%
1398
September1st to 15thNight
38%
540
2%
1724
2%
540
38%
540
8%
1465
September16th to endNight
37%
538
3%
1953
5%
538
37%
538
6%
1628
October1st to 15thNight
37%
693
5%
2268
5%
693
38%
693
9%
1861
October16th to endNight
44%
816
6%
2675
5%
816
44%
816
10%
2150
November1st to 15thNight
43%
805
5%
2891
4%
805
44%
805
10%
2296
November16th to endNight
46%
825
8%
3309
10%
825
47%
825
11%
2454
December1st to 15thNight
46%
854
7%
3440
9%
854
47%
854
10%
2624
December16th to endNight
47%
928
7%
3744
7%
928
49%
928
11%
2778

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%49%9%46%6%6%7%22%
49191
Night
6%9%5%10%9%5%7%6%6%7%25%
48526
TransparencyDay
56%15%14%9%3
48792
Night
49%17%15%10%5%
48430
SeeingDay
15%5%21%28%20%8%
8540
Night
7%320%33%25%9%
13713

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
27%5%12%11%5%7%6%47%27%
786
16th to endDay
17%5%13%13%7%11%8%8%6%15%
1164
February1st to 15thDay
7%5%10%11%6%8%6%6%7%28%
1241
16th to endDay
16%411%10%5%7%8%7%9%27%
1293
March1st to 15thDay
4411%13%48%7%5%7%32%
1800
16th to endDay
16%5%13%11%5%7%7%7%6%26%
2205
April1st to 15thDay
310%7%9%9%47%6%8%8%25%
2300
16th to endDay
211%5%8%8%35%5%8%8%31%
2586
May1st to 15thDay
7%14%39%7%46%6%6%7%27%
2820
16th to endDay
9%8%35%7%48%6%7%7%31%
3206
June1st to 15thDay
23%10%48%7%45%5%5%5%17%
3240
16th to endDay
27%8%38%7%45%5%5%5%18%
3240
July1st to 15thDay
26%8%47%7%46%6%5%6%14%
3240
16th to endDay
22%9%5%7%8%46%5%5%7%16%
3158
August1st to 15thDay
21%10%48%8%45%6%5%7%17%
2813
16th to endDay
27%12%5%9%7%45%5%45%12%
2659
September1st to 15thDay
17%11%39%8%45%45%7%21%
2235
16th to endDay
12%15%5%10%7%46%5%5%5%20%
2007
October1st to 15thDay
7%16%5%11%8%25%5%5%6%25%
1692
16th to endDay
413%6%14%10%46%45%6%22%
1548
November1st to 15thDay
213%5%13%13%6%9%5%46%18%
1297
16th to endDay
6%6%14%13%8%9%6%47%23%
981
December1st to 15thDay
28%6%12%12%6%6%8%7%6%21%
848
16th to endDay
5%5%11%14%5%11%7%7%8%21%
832
January1st to 15thNight
17%5%12%11%6%8%7%6%8%25%
3483
16th to endNight
27%5%13%12%7%7%6%6%8%21%
3164
February1st to 15thNight
15%410%9%6%8%7%6%7%31%
2609
16th to endNight
26%49%9%5%6%6%6%10%31%
2179
March1st to 15thNight
447%7%5%8%8%8%7%36%
2160
16th to endNight
15%6%9%11%47%6%7%8%32%
2012
April1st to 15thNight
29%7%10%8%47%6%6%8%25%
1647
16th to endNight
39%47%8%46%7%7%9%31%
1374
May1st to 15thNight
9%14%5%8%7%5%6%7%45%26%
1130
16th to endNight
9%9%35%6%445%7%7%36%
906
June1st to 15thNight
21%9%47%5%15%6%6%7%23%
720
16th to endNight
22%9%48%6%45%35%7%21%
720
July1st to 15thNight
25%7%35%6%46%5%47%22%
720
16th to endNight
21%8%38%7%5%5%5%46%21%
1010
August1st to 15thNight
13%10%48%10%46%6%5%6%23%
1145
16th to endNight
22%14%48%6%45%5%6%5%16%
1543
September1st to 15thNight
17%12%47%7%45%5%6%6%21%
1724
16th to endNight
13%18%46%7%35%45%7%21%
1953
October1st to 15thNight
9%18%410%7%445%5%5%23%
2268
16th to endNight
414%7%13%8%445%5%6%24%
2675
November1st to 15thNight
311%7%14%11%6%7%5%46%20%
2891
16th to endNight
17%6%13%12%6%7%7%5%7%22%
3309
December1st to 15thNight
39%6%13%11%5%9%5%6%7%21%
3440
16th to endNight
16%5%13%12%6%9%7%6%8%21%
3744

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
44%16%13%15%7%3
786
16th to endDay
48%18%16%10%5%
1164
February1st to 15thDay
42%14%17%13%9%2
1241
16th to endDay
39%15%18%15%10%
1293
March1st to 15thDay
43%11%13%15%12%2
1800
16th to endDay
49%15%13%11%7%1
2205
April1st to 15thDay
53%16%14%11%3
2300
16th to endDay
48%14%18%15%4
2586
May1st to 15thDay
55%12%14%13%3
2820
16th to endDay
42%16%18%15%6%
3210
June1st to 15thDay
64%12%13%8%1
3240
16th to endDay
64%13%12%7%1
3240
July1st to 15thDay
67%14%13%3
3051
16th to endDay
64%17%14%3
2963
August1st to 15thDay
61%19%14%5%
2794
16th to endDay
73%13%8%3
2659
September1st to 15thDay
58%18%13%8%1
2235
16th to endDay
62%17%10%8%1
2007
October1st to 15thDay
55%17%13%8%4
1692
16th to endDay
52%20%14%8%31
1548
November1st to 15thDay
54%17%14%8%4
1297
16th to endDay
48%17%14%11%8%
981
December1st to 15thDay
49%21%14%10%4
848
16th to endDay
44%18%17%12%4
832
January1st to 15thNight
44%16%16%12%6%3
3483
16th to endNight
43%19%17%12%5%
3164
February1st to 15thNight
38%14%15%16%11%2
2621
16th to endNight
38%16%19%15%8%1
2179
March1st to 15thNight
35%15%14%14%16%3
2160
16th to endNight
40%17%13%15%11%2
2017
April1st to 15thNight
51%15%17%11%3
1647
16th to endNight
46%17%19%12%3
1374
May1st to 15thNight
58%13%10%14%3
1131
16th to endNight
42%17%18%14%6%
906
June1st to 15thNight
57%18%15%8%1
720
16th to endNight
61%15%12%8%1
720
July1st to 15thNight
64%13%16%5%
680
16th to endNight
62%18%16%2
942
August1st to 15thNight
57%20%16%4
1139
16th to endNight
67%18%9%4
1543
September1st to 15thNight
59%18%14%7%1
1724
16th to endNight
59%17%12%7%1
1953
October1st to 15thNight
55%17%13%7%4
2268
16th to endNight
54%17%14%8%4
2675
November1st to 15thNight
54%17%15%9%4
2891
16th to endNight
48%16%15%12%6%
3309
December1st to 15thNight
49%18%14%10%7%
3440
16th to endNight
46%18%16%10%6%
3744

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
228%35%24%8%
45
16th to endDay
1218%40%25%10%
220
February1st to 15thDay
419%34%28%13%
221
16th to endDay
6%27%34%23%8%
211
March1st to 15thDay
5%23%35%22%12%
240
16th to endDay
2221%28%28%16%
382
April1st to 15thDay
3329%27%23%11%
439
16th to endDay
6%6%18%28%31%9%
450
May1st to 15thDay
14%422%26%23%8%
468
16th to endDay
8%5%24%31%23%7%
554
June1st to 15thDay
22%423%30%15%3
675
16th to endDay
23%315%28%20%8%
675
July1st to 15thDay
28%5%15%23%19%7%
645
16th to endDay
24%419%28%17%5%
556
August1st to 15thDay
19%8%26%23%15%7%
494
16th to endDay
33%9%21%20%13%1
523
September1st to 15thDay
23%8%32%18%12%4
469
16th to endDay
17%12%23%25%13%8%
300
October1st to 15thDay
13%6%23%28%19%8%
270
16th to endDay
6%6%16%24%31%14%
288
November1st to 15thDay
5%217%39%22%11%
271
16th to endDay
111%39%25%21%
51
December1st to 15thDay
6%20%24%26%22%
45
16th to endDay
216%39%31%10%
48
January1st to 15thNight
1224%36%25%9%
868
16th to endNight
2224%38%23%9%
825
February1st to 15thNight
224%38%24%9%
734
16th to endNight
1228%38%22%6%
638
March1st to 15thNight
121%38%27%9%
570
16th to endNight
1113%29%34%20%
581
April1st to 15thNight
1220%31%28%14%
539
16th to endNight
5%216%31%33%10%
540
May1st to 15thNight
12%217%28%29%9%
411
16th to endNight
7%321%29%33%4
196
June1st to 15thNight
20%312%35%24%3
180
16th to endNight
27%312%23%27%5%
180
July1st to 15thNight
29%213%20%27%6%
170
16th to endNight
22%214%26%26%8%
295
August1st to 15thNight
16%420%29%21%7%
414
16th to endNight
24%5%20%25%17%5%
573
September1st to 15thNight
21%5%22%26%20%4
540
16th to endNight
18%6%21%26%18%9%
538
October1st to 15thNight
13%7%22%26%24%6%
693
16th to endNight
7%216%31%31%9%
816
November1st to 15thNight
5%217%45%22%6%
805
16th to endNight
1323%33%28%9%
825
December1st to 15thNight
3320%32%25%12%
854
16th to endNight
2220%37%23%13%
928
Page generated at 2018-01-21 08:19:32. Version ac04

Copyright 2018 A. Danko


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