This page made possible by the sponsorship of: Mark A McLaughlin.

Loon Lake Road Observing Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Loon Lake Road Observing Site 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
36%
15369
10%
48852
7%
15341
39%
15341
16%
35084

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
26%
817
6%
2875
5%
813
27%
813
8%
2356
January16th to endNight
29%
832
7%
2912
7%
832
31%
832
10%
2248
February1st to 15thNight
27%
757
7%
2558
5%
757
30%
757
9%
2037
February16th to endNight
36%
660
12%
2081
10%
660
40%
660
14%
1541
March1st to 15thNight
25%
720
7%
2136
4%
720
29%
720
11%
1681
March16th to endNight
28%
768
8%
2018
3%
768
31%
768
13%
1580
April1st to 15thNight
34%
719
8%
1799
3%
719
36%
719
16%
1372
April16th to endNight
37%
495
10%
1575
6%
495
42%
495
16%
1134
May1st to 15thNight
43%
359
11%
1439
15%
359
49%
359
20%
896
May16th to endNight
46%
374
6%
1496
8%
374
48%
374
16%
1005
June1st to 15thNight
39%
360
2%
1185
0%
360
39%
360
18%
810
June16th to endNight
40%
360
5%
1120
0%
360
40%
360
23%
715
July1st to 15thNight
58%
340
7%
1190
3%
340
60%
340
35%
614
July16th to endNight
60%
376
14%
1402
18%
354
66%
354
44%
597
August1st to 15thNight
72%
360
18%
1432
25%
358
75%
358
41%
635
August16th to endNight
55%
637
21%
1783
13%
637
60%
637
36%
1046
September1st to 15thNight
57%
720
21%
1800
10%
720
61%
720
40%
1075
September16th to endNight
46%
716
20%
1951
12%
716
51%
716
28%
1282
October1st to 15thNight
41%
720
13%
2160
11%
720
45%
720
21%
1471
October16th to endNight
33%
768
11%
2450
8%
768
39%
768
14%
1792
November1st to 15thNight
22%
760
7%
2621
5%
760
26%
760
9%
2107
November16th to endNight
25%
783
6%
2733
3%
783
30%
783
9%
2123
December1st to 15thNight
32%
975
8%
2925
6%
975
34%
975
12%
2315
December16th to endNight
22%
993
6%
3211
4%
993
25%
993
7%
2652

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
9%10%47%6%35%5%5%7%33%
49407
Night
8%10%47%6%35%5%6%7%34%
49009
Cloud CoverDay
10%10%48%6%35%5%5%6%32%
49407
Night
8%11%47%6%35%5%5%7%33%
49012
TransparencyDay
51%8%13%16%8%1
49067
Night
48%9%15%17%7%1
48853
SeeingDay
17%20%29%20%10%2
6512
Night
14%14%27%25%14%2
15378

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
10%11%6%9%8%47%6%6%7%19%
1391
16th to endDay
9%14%5%7%6%35%6%6%8%25%
1664
February1st to 15thDay
6%17%7%10%8%36%6%6%7%17%
1635
16th to endDay
5%15%7%10%8%46%47%6%23%
1539
March1st to 15thDay
7%16%6%12%7%46%45%6%21%
1821
16th to endDay
7%15%8%10%8%46%6%6%7%18%
2205
April1st to 15thDay
11%15%6%9%7%46%5%5%6%20%
2149
16th to endDay
10%14%5%9%6%35%5%6%7%24%
2384
May1st to 15thDay
8%11%48%6%35%46%7%32%
2511
16th to endDay
15%10%47%7%36%5%6%7%24%
2615
June1st to 15thDay
16%8%47%6%35%5%5%6%30%
2770
16th to endDay
12%6%26%7%35%45%7%37%
2836
July1st to 15thDay
5%3245%2445%7%54%
2700
16th to endDay
6%213424447%58%
2669
August1st to 15thDay
5%31443445%7%53%
2520
16th to endDay
7%415%4345%6%7%48%
2416
September1st to 15thDay
9%5%25%5%23335%52%
2160
16th to endDay
13%7%26%5%35%447%36%
2005
October1st to 15thDay
10%10%48%5%445%5%6%34%
1800
16th to endDay
12%11%5%7%8%35%5%5%6%28%
1773
November1st to 15thDay
16%15%6%8%6%35%5%5%6%20%
1564
16th to endDay
7%16%5%8%7%36%6%6%6%23%
1543
December1st to 15thDay
6%12%6%10%9%35%7%6%5%25%
1365
16th to endDay
8%15%7%12%9%36%5%5%7%20%
1372
January1st to 15thNight
11%14%6%11%7%45%5%5%6%20%
2875
16th to endNight
9%13%6%9%7%36%5%7%7%22%
2912
February1st to 15thNight
9%15%5%10%7%35%5%6%5%23%
2546
16th to endNight
310%7%10%9%45%5%5%7%30%
2081
March1st to 15thNight
6%13%6%8%7%46%6%8%7%25%
2136
16th to endNight
6%11%6%8%7%5%6%6%6%7%28%
2014
April1st to 15thNight
5%9%49%7%46%6%6%7%32%
1799
16th to endNight
6%10%47%6%46%6%5%9%32%
1575
May1st to 15thNight
7%8%35%5%25%5%6%7%43%
1439
16th to endNight
10%7%346%26%5%7%8%36%
1496
June1st to 15thNight
10%7%35%5%36%5%5%9%36%
1185
16th to endNight
6%6%35%4245%6%7%45%
1120
July1st to 15thNight
33133145%5%7%59%
1260
16th to endNight
411221236%8%65%
1497
August1st to 15thNight
32221345%7%64%
1440
16th to endNight
4314325%45%7%55%
1783
September1st to 15thNight
7%4232345%6%58%
1800
16th to endNight
9%6%2442446%9%43%
1951
October1st to 15thNight
8%8%37%6%345%5%6%41%
2160
16th to endNight
12%10%46%6%45%5%6%6%31%
2450
November1st to 15thNight
12%15%5%9%6%35%6%6%6%22%
2621
16th to endNight
9%13%6%9%7%45%5%5%6%25%
2733
December1st to 15thNight
7%15%5%8%7%35%6%6%6%26%
2925
16th to endNight
8%14%6%11%8%5%6%5%6%6%20%
3211

Percentage Cloud Cover SW (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
10%12%5%10%8%49%5%7%6%19%
1391
16th to endDay
9%14%5%7%6%36%5%6%8%25%
1664
February1st to 15thDay
7%17%6%12%7%36%6%6%6%18%
1635
16th to endDay
6%16%7%11%7%46%5%5%6%23%
1539
March1st to 15thDay
7%18%7%11%7%46%45%5%20%
1821
16th to endDay
7%17%7%10%8%36%6%6%6%17%
2205
April1st to 15thDay
11%15%6%10%8%46%5%5%6%19%
2149
16th to endDay
10%14%6%8%7%36%5%6%7%23%
2384
May1st to 15thDay
9%12%48%6%35%5%5%7%31%
2511
16th to endDay
15%11%48%7%36%5%6%7%23%
2615
June1st to 15thDay
18%8%48%6%35%446%29%
2770
16th to endDay
13%6%36%7%445%5%6%36%
2836
July1st to 15thDay
6%325%434447%53%
2700
16th to endDay
6%323324447%58%
2669
August1st to 15thDay
5%3145%345%5%7%52%
2520
16th to endDay
7%425%5%3446%8%47%
2416
September1st to 15thDay
9%5%25%5%23336%52%
2160
16th to endDay
13%8%36%5%35%447%36%
2005
October1st to 15thDay
10%10%5%8%6%345%5%6%32%
1800
16th to endDay
12%12%5%8%7%35%5%5%6%28%
1773
November1st to 15thDay
15%15%7%8%6%45%5%5%5%19%
1564
16th to endDay
7%16%6%9%6%36%5%6%6%23%
1543
December1st to 15thDay
6%12%6%11%8%36%6%6%6%25%
1365
16th to endDay
8%15%7%13%9%35%45%7%19%
1372
January1st to 15thNight
12%14%6%11%7%46%5%46%20%
2874
16th to endNight
9%14%6%9%7%36%5%6%7%22%
2912
February1st to 15thNight
9%16%6%9%7%35%5%6%6%23%
2546
16th to endNight
310%6%11%10%45%45%6%29%
2081
March1st to 15thNight
6%14%7%8%6%47%5%7%7%24%
2136
16th to endNight
6%13%47%8%46%6%5%7%28%
2018
April1st to 15thNight
5%10%48%7%46%6%6%7%30%
1799
16th to endNight
6%10%48%7%47%5%6%9%32%
1575
May1st to 15thNight
7%8%35%5%25%45%7%42%
1439
16th to endNight
10%8%26%5%35%6%6%8%35%
1496
June1st to 15thNight
11%7%35%6%36%5%5%8%35%
1185
16th to endNight
7%6%34426%5%6%7%44%
1120
July1st to 15thNight
33133146%5%6%59%
1260
16th to endNight
421221235%8%64%
1497
August1st to 15thNight
4232135%5%7%64%
1440
16th to endNight
5%314425%5%5%6%55%
1783
September1st to 15thNight
7%41242345%6%57%
1800
16th to endNight
9%7%2442447%9%43%
1951
October1st to 15thNight
8%8%37%6%345%46%40%
2160
16th to endNight
12%12%36%6%35%5%6%6%31%
2450
November1st to 15thNight
12%16%5%9%6%45%6%5%5%22%
2621
16th to endNight
9%14%6%10%7%45%5%46%25%
2733
December1st to 15thNight
7%16%5%9%7%45%5%5%7%26%
2925
16th to endNight
8%14%6%11%9%46%5%6%6%20%
3211

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
62%10%11%10%3
1391
16th to endDay
55%9%14%14%41
1664
February1st to 15thDay
63%11%11%7%5%
1635
16th to endDay
61%9%11%12%5%
1539
March1st to 15thDay
64%8%11%12%2
1821
16th to endDay
64%9%14%9%2
2205
April1st to 15thDay
64%9%10%11%2
2149
16th to endDay
58%10%14%11%4
2384
May1st to 15thDay
51%7%13%16%9%
2511
16th to endDay
58%9%14%14%3
2619
June1st to 15thDay
55%7%13%15%5%1
2770
16th to endDay
47%9%15%17%9%
2836
July1st to 15thDay
30%7%13%24%19%4
2541
16th to endDay
25%7%13%27%20%4
2501
August1st to 15thDay
30%7%16%27%13%4
2503
16th to endDay
32%8%15%27%12%3
2416
September1st to 15thDay
35%413%24%18%2
2160
16th to endDay
47%7%13%18%9%3
2005
October1st to 15thDay
51%8%14%18%6%
1800
16th to endDay
55%8%13%17%4
1773
November1st to 15thDay
65%9%10%10%31
1564
16th to endDay
58%9%12%13%41
1543
December1st to 15thDay
57%12%14%11%4
1365
16th to endDay
65%10%10%11%2
1372
January1st to 15thNight
64%9%11%10%3
2875
16th to endNight
58%9%13%12%41
2912
February1st to 15thNight
60%9%12%11%4
2558
16th to endNight
53%8%13%17%6%
2081
March1st to 15thNight
55%11%16%13%3
2136
16th to endNight
53%11%17%14%2
2018
April1st to 15thNight
50%10%17%17%3
1799
16th to endNight
48%10%20%17%3
1575
May1st to 15thNight
39%9%19%21%10%
1440
16th to endNight
43%11%19%20%3
1496
June1st to 15thNight
44%9%18%18%6%1
1185
16th to endNight
34%12%22%20%9%
1120
July1st to 15thNight
23%8%16%28%17%5%
1190
16th to endNight
17%419%31%20%5%
1402
August1st to 15thNight
17%8%22%29%18%3
1432
16th to endNight
27%8%17%28%14%2
1783
September1st to 15thNight
26%7%15%28%18%4
1800
16th to endNight
36%9%15%22%11%3
1951
October1st to 15thNight
43%8%16%21%9%
2160
16th to endNight
52%7%14%20%4
2450
November1st to 15thNight
61%10%11%10%4
2621
16th to endNight
58%10%13%12%41
2733
December1st to 15thNight
57%10%12%14%3
2925
16th to endNight
62%12%11%10%3
3211

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
7%8%27%18%25%11%
90
16th to endDay
15%25%37%17%4
96
February1st to 15thDay
25%19%29%19%5%
205
16th to endDay
15%22%34%19%7%
241
March1st to 15thDay
30%34%23%9%2
270
16th to endDay
24%34%22%15%2
288
April1st to 15thDay
26%26%26%14%41
269
16th to endDay
22%28%27%13%7%1
270
May1st to 15thDay
20%21%31%18%5%2
288
16th to endDay
25%13%23%18%15%3
330
June1st to 15thDay
20%17%30%18%12%1
565
16th to endDay
16%17%30%20%12%1
631
July1st to 15thDay
7%17%36%28%8%
475
16th to endDay
8%15%36%25%10%2
338
August1st to 15thDay
7%9%26%31%16%7%
315
16th to endDay
9%15%35%24%11%3
332
September1st to 15thDay
14%17%27%20%17%1
315
16th to endDay
17%20%23%22%11%4
315
October1st to 15thDay
20%20%28%14%12%2
315
16th to endDay
20%17%26%21%13%
189
November1st to 15thDay
25%25%31%14%22
99
16th to endDay
14%30%28%12%6%7%
90
December1st to 15thDay
15%11%24%21%17%10%
90
16th to endDay
20%15%32%19%9%2
96
January1st to 15thNight
21%14%28%20%13%2
817
16th to endNight
15%15%31%23%11%2
832
February1st to 15thNight
20%13%24%27%11%3
764
16th to endNight
8%17%26%27%18%1
660
March1st to 15thNight
16%22%28%21%8%1
720
16th to endNight
14%21%29%23%8%2
768
April1st to 15thNight
13%15%28%28%12%2
719
16th to endNight
11%14%31%28%12%1
495
May1st to 15thNight
13%10%27%29%17%2
360
16th to endNight
14%5%26%30%21%1
375
June1st to 15thNight
13%11%30%28%15%1
360
16th to endNight
8%13%33%28%13%1
360
July1st to 15thNight
5%9%22%39%21%1
340
16th to endNight
5%6%26%39%21%1
376
August1st to 15thNight
5%217%35%32%6%
360
16th to endNight
7%7%25%29%26%3
637
September1st to 15thNight
10%7%21%23%27%9%
720
16th to endNight
14%9%25%22%24%4
716
October1st to 15thNight
14%11%25%26%19%2
720
16th to endNight
19%17%25%22%13%2
768
November1st to 15thNight
22%19%30%19%6%
760
16th to endNight
18%19%27%21%10%2
783
December1st to 15thNight
16%15%26%28%11%1
975
16th to endNight
15%20%31%25%6%
993
Page generated at 2018-02-23 08:21:37. Version ac04

Copyright 2018 A. Danko


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