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 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
36%
14557
9%
46346
7%
14529
39%
14529
16%
33325

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%
745
6%
2653
6%
741
26%
741
8%
2176
January16th to endNight
30%
768
7%
2688
7%
768
32%
768
11%
2066
February1st to 15thNight
29%
697
6%
2357
5%
697
31%
697
9%
1876
February16th to endNight
36%
632
12%
1990
9%
632
40%
632
15%
1464
March1st to 15thNight
25%
720
7%
2136
4%
720
28%
720
11%
1681
March16th to endNight
27%
768
8%
2018
3%
768
30%
768
13%
1580
April1st to 15thNight
34%
719
8%
1799
3%
719
36%
719
16%
1372
April16th to endNight
36%
495
10%
1575
6%
495
41%
495
16%
1134
May1st to 15thNight
42%
359
11%
1439
15%
359
48%
359
20%
896
May16th to endNight
46%
374
6%
1496
8%
374
48%
374
16%
1005
June1st to 15thNight
37%
360
2%
1185
0%
360
38%
360
18%
810
June16th to endNight
39%
360
5%
1120
0%
360
39%
360
23%
715
July1st to 15thNight
58%
340
7%
1190
3%
340
61%
340
35%
614
July16th to endNight
59%
376
14%
1402
18%
354
66%
354
44%
597
August1st to 15thNight
72%
352
18%
1400
25%
350
76%
350
41%
621
August16th to endNight
53%
583
18%
1633
12%
583
57%
583
34%
984
September1st to 15thNight
57%
660
21%
1650
10%
660
60%
660
39%
1003
September16th to endNight
45%
656
18%
1788
10%
656
49%
656
27%
1187
October1st to 15thNight
41%
660
13%
1980
11%
660
45%
660
21%
1352
October16th to endNight
33%
704
10%
2246
7%
704
38%
704
13%
1668
November1st to 15thNight
22%
700
8%
2414
5%
700
25%
700
9%
1932
November16th to endNight
26%
723
6%
2523
3%
723
30%
723
10%
1969
December1st to 15thNight
29%
900
8%
2700
5%
900
31%
900
11%
2178
December16th to endNight
22%
906
6%
2964
3%
906
25%
906
7%
2445

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%
47636
Night
8%10%47%6%35%5%6%7%34%
46503
Cloud CoverDay
10%10%48%6%35%5%5%6%32%
47636
Night
8%11%47%6%35%5%5%7%33%
46506
TransparencyDay
51%8%13%16%7%1
47296
Night
49%9%15%17%6%1
46347
SeeingDay
17%20%29%20%10%2
5956
Night
14%14%27%25%14%2
14566

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
11%11%6%9%8%47%6%6%7%20%
1283
16th to endDay
8%15%5%7%6%35%5%6%8%26%
1536
February1st to 15thDay
6%17%7%10%8%37%6%6%8%16%
1506
16th to endDay
5%15%7%10%8%46%47%6%23%
1484
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%41443445%6%53%
2467
16th to endDay
7%5%16%435%5%6%7%46%
2214
September1st to 15thDay
9%6%26%5%33335%51%
1980
16th to endDay
13%7%26%5%34448%37%
1839
October1st to 15thDay
10%10%48%5%445%5%5%34%
1650
16th to endDay
12%11%5%7%8%35%5%5%7%27%
1625
November1st to 15thDay
17%15%6%7%6%35%5%5%6%20%
1441
16th to endDay
7%16%5%8%7%36%6%6%6%24%
1425
December1st to 15thDay
6%12%6%11%9%35%7%5%5%24%
1260
16th to endDay
7%14%7%12%9%36%5%6%7%20%
1266
January1st to 15thNight
11%15%6%11%7%45%5%5%6%20%
2653
16th to endNight
9%13%6%9%7%36%5%6%7%23%
2688
February1st to 15thNight
8%15%6%10%7%35%5%7%6%23%
2345
16th to endNight
49%7%9%9%45%5%5%7%31%
1990
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%
1408
16th to endNight
4314436%5%6%7%52%
1633
September1st to 15thNight
8%423235%5%6%57%
1650
16th to endNight
9%7%25%42446%9%42%
1788
October1st to 15thNight
8%8%37%6%346%5%6%40%
1980
16th to endNight
12%11%46%6%45%5%6%6%30%
2246
November1st to 15thNight
12%14%5%9%6%35%6%6%7%23%
2414
16th to endNight
9%14%6%9%6%445%5%5%25%
2523
December1st to 15thNight
7%16%5%8%7%35%5%6%6%24%
2700
16th to endNight
8%13%6%11%8%5%6%5%6%6%21%
2964

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
11%11%5%10%8%49%5%6%7%20%
1283
16th to endDay
8%15%5%7%6%36%5%5%8%26%
1536
February1st to 15thDay
6%17%7%12%7%47%6%6%6%16%
1506
16th to endDay
6%15%8%11%7%46%5%5%6%23%
1484
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%
2467
16th to endDay
8%425%5%3447%8%45%
2214
September1st to 15thDay
10%6%26%5%23336%51%
1980
16th to endDay
13%8%36%5%35%448%36%
1839
October1st to 15thDay
10%10%48%7%345%46%33%
1650
16th to endDay
13%12%5%7%7%35%45%6%27%
1625
November1st to 15thDay
16%15%7%7%6%45%45%5%19%
1441
16th to endDay
7%15%6%9%6%36%6%6%6%24%
1425
December1st to 15thDay
6%13%7%11%8%36%6%5%5%24%
1260
16th to endDay
7%15%7%13%9%35%5%5%7%19%
1266
January1st to 15thNight
12%15%6%12%7%46%45%6%19%
2652
16th to endNight
9%14%6%9%7%36%5%6%6%23%
2688
February1st to 15thNight
8%15%6%10%7%35%5%6%6%23%
2345
16th to endNight
310%6%10%10%46%45%7%30%
1990
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
3232135%5%7%64%
1408
16th to endNight
5%314435%5%6%7%51%
1633
September1st to 15thNight
8%41242345%6%56%
1650
16th to endNight
9%7%25%5%2446%9%42%
1788
October1st to 15thNight
8%8%37%6%345%5%6%41%
1980
16th to endNight
13%13%36%6%35%5%6%6%29%
2246
November1st to 15thNight
12%16%5%9%6%45%5%5%5%23%
2414
16th to endNight
10%14%6%9%6%45%5%45%25%
2523
December1st to 15thNight
7%16%6%9%7%46%5%5%7%24%
2700
16th to endNight
8%13%6%11%9%46%5%6%6%20%
2964

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
61%10%11%10%31
1283
16th to endDay
55%8%15%14%41
1536
February1st to 15thDay
63%11%11%7%4
1506
16th to endDay
60%9%11%12%5%
1484
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
2450
16th to endDay
34%8%15%25%12%2
2214
September1st to 15thDay
37%413%24%16%2
1980
16th to endDay
46%7%13%18%9%3
1839
October1st to 15thDay
51%8%14%19%6%
1650
16th to endDay
56%8%14%16%3
1625
November1st to 15thDay
65%9%10%10%21
1441
16th to endDay
57%10%12%13%41
1425
December1st to 15thDay
59%12%14%10%3
1260
16th to endDay
64%10%10%11%2
1266
January1st to 15thNight
64%9%11%9%3
2653
16th to endNight
57%9%13%12%41
2688
February1st to 15thNight
60%10%13%11%3
2357
16th to endNight
52%8%13%17%6%
1990
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%23%29%18%3
1400
16th to endNight
29%9%17%26%14%2
1633
September1st to 15thNight
27%8%15%28%16%4
1650
16th to endNight
37%9%15%21%10%4
1788
October1st to 15thNight
43%8%16%21%9%
1980
16th to endNight
54%7%14%19%3
2246
November1st to 15thNight
60%10%12%11%41
2414
16th to endNight
58%10%13%11%41
2523
December1st to 15thNight
60%10%11%14%2
2700
16th to endNight
61%13%11%10%2
2964

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
38%30%23%26%8%
60
16th to endDay
12%17%43%20%6%
64
February1st to 15thDay
22%20%28%20%6%1
166
16th to endDay
15%22%33%19%8%
222
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%27%33%15%7%
300
16th to endDay
10%16%38%22%10%1
268
September1st to 15thDay
14%18%26%20%17%1
255
16th to endDay
19%22%23%20%10%3
255
October1st to 15thDay
21%21%27%15%12%1
255
16th to endDay
18%13%29%25%13%
137
November1st to 15thDay
28%24%34%10%1
66
16th to endDay
10%23%26%18%10%11%
60
December1st to 15thDay
23%15%28%16%13%3
60
16th to endDay
15%20%35%14%10%3
64
January1st to 15thNight
21%16%29%19%11%1
745
16th to endNight
15%14%30%24%12%2
768
February1st to 15thNight
18%13%24%28%11%3
704
16th to endNight
8%16%26%27%18%1
632
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%7%
352
16th to endNight
8%8%25%29%24%3
583
September1st to 15thNight
10%7%20%23%27%10%
660
16th to endNight
14%9%26%21%23%4
656
October1st to 15thNight
13%12%26%25%18%2
660
16th to endNight
19%16%24%22%13%2
704
November1st to 15thNight
22%20%32%18%6%
700
16th to endNight
18%17%27%22%11%2
723
December1st to 15thNight
17%16%27%28%10%
900
16th to endNight
13%22%32%24%6%
906
Page generated at 2017-08-13 11:16:46. Version ac04

Copyright 2017 A. Danko


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