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 2017-03-26.

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%
14234
9%
45270
7%
14206
39%
14206
16%
32733

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
28%
748
7%
1968
2%
748
30%
748
13%
1540
April1st to 15thNight
35%
659
8%
1649
3%
659
37%
659
16%
1257
April16th to endNight
37%
454
9%
1444
5%
454
41%
454
17%
1038
May1st to 15thNight
43%
329
12%
1319
16%
329
48%
329
20%
829
May16th to endNight
45%
342
5%
1368
6%
342
47%
342
15%
934
June1st to 15thNight
36%
330
3%
1086
0%
330
36%
330
16%
759
June16th to endNight
38%
330
4%
1026
0%
330
38%
330
22%
667
July1st to 15thNight
56%
310
8%
1085
3%
310
58%
310
33%
576
July16th to endNight
60%
348
13%
1291
15%
326
66%
326
43%
555
August1st to 15thNight
70%
330
18%
1312
26%
328
74%
328
39%
597
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
10%10%47%6%35%5%5%7%32%
45713
Night
8%10%47%6%35%5%6%7%33%
45427
Cloud CoverDay
10%11%48%6%35%5%5%6%31%
45713
Night
8%11%47%6%35%5%5%7%33%
45430
TransparencyDay
51%8%13%16%7%1
45373
Night
49%9%15%17%6%1
45271
SeeingDay
18%20%29%20%9%1
5347
Night
14%14%27%25%14%2
14243

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%14%8%10%8%46%6%6%7%19%
2141
April1st to 15thDay
11%15%6%9%7%46%5%5%7%20%
1969
16th to endDay
9%14%5%9%6%35%5%6%8%24%
2185
May1st to 15thDay
8%11%47%6%35%46%7%31%
2301
16th to endDay
15%11%48%8%36%5%7%7%22%
2391
June1st to 15thDay
17%9%47%6%345%46%30%
2539
16th to endDay
13%6%26%7%35%5%5%6%35%
2600
July1st to 15thDay
6%4245%245%5%7%51%
2475
16th to endDay
6%213434447%56%
2472
August1st to 15thDay
5%415%5%35%46%7%50%
2310
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%46%6%6%7%28%
1964
April1st to 15thNight
5%9%49%6%46%6%5%7%32%
1649
16th to endNight
5%10%47%6%46%6%6%9%32%
1444
May1st to 15thNight
7%8%35%5%25%5%6%6%43%
1319
16th to endNight
10%7%246%26%6%7%8%34%
1368
June1st to 15thNight
11%7%36%6%36%5%5%8%34%
1086
16th to endNight
6%6%35%4245%6%7%44%
1026
July1st to 15thNight
33133246%5%7%57%
1155
16th to endNight
421221236%8%64%
1386
August1st to 15thNight
321221345%8%63%
1320
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%16%7%10%8%36%6%7%6%18%
2141
April1st to 15thDay
11%15%6%10%7%46%5%5%6%20%
1969
16th to endDay
10%14%6%8%7%36%46%7%23%
2185
May1st to 15thDay
9%12%38%6%35%5%5%7%31%
2301
16th to endDay
16%11%48%7%46%5%6%7%21%
2391
June1st to 15thDay
19%8%48%6%25%446%29%
2539
16th to endDay
14%6%36%7%445%5%6%34%
2600
July1st to 15thDay
6%425%4345%47%51%
2475
16th to endDay
6%323424447%56%
2472
August1st to 15thDay
6%315%5%345%5%7%49%
2310
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%48%8%46%6%6%7%28%
1968
April1st to 15thNight
5%11%5%8%7%46%6%6%7%31%
1649
16th to endNight
6%10%47%6%47%5%6%9%32%
1444
May1st to 15thNight
7%9%36%5%25%45%7%42%
1319
16th to endNight
10%8%26%5%35%7%6%8%33%
1368
June1st to 15thNight
12%7%45%6%46%45%8%34%
1086
16th to endNight
7%6%35%426%5%6%6%43%
1026
July1st to 15thNight
33133146%5%7%57%
1155
16th to endNight
421221335%8%63%
1386
August1st to 15thNight
42132135%5%7%62%
1320
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
2141
April1st to 15thDay
64%9%11%11%2
1969
16th to endDay
58%10%15%11%4
2185
May1st to 15thDay
51%7%14%17%8%
2301
16th to endDay
60%9%14%13%2
2395
June1st to 15thDay
56%7%13%14%5%1
2539
16th to endDay
48%10%15%16%8%
2600
July1st to 15thDay
32%7%14%24%17%3
2316
16th to endDay
27%7%14%27%18%4
2304
August1st to 15thDay
32%8%17%28%10%2
2293
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
1968
April1st to 15thNight
50%10%18%17%3
1649
16th to endNight
47%10%21%17%2
1444
May1st to 15thNight
39%9%19%21%9%
1320
16th to endNight
44%12%21%17%3
1368
June1st to 15thNight
47%9%17%16%6%1
1086
16th to endNight
36%12%23%19%8%
1026
July1st to 15thNight
24%8%17%28%16%4
1085
16th to endNight
18%5%20%31%19%4
1291
August1st to 15thNight
18%8%24%30%14%2
1312
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
22%35%22%16%2
267
April1st to 15thDay
27%26%23%15%41
209
16th to endDay
21%30%24%12%8%1
210
May1st to 15thDay
20%21%31%17%6%3
228
16th to endDay
27%14%24%18%12%2
266
June1st to 15thDay
21%17%28%19%11%
484
16th to endDay
16%18%31%20%12%1
545
July1st to 15thDay
8%19%34%29%8%
400
16th to endDay
8%15%39%24%8%2
281
August1st to 15thDay
8%11%30%32%12%3
255
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
13%21%29%24%8%2
748
April1st to 15thNight
13%16%27%27%13%2
659
16th to endNight
11%15%30%27%13%1
454
May1st to 15thNight
13%10%27%28%18%2
330
16th to endNight
14%6%27%29%20%
343
June1st to 15thNight
14%11%30%27%14%1
330
16th to endNight
9%13%34%29%12%1
330
July1st to 15thNight
6%9%24%34%23%1
310
16th to endNight
46%26%40%20%1
348
August1st to 15thNight
6%218%36%31%6%
330
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 2017-03-27 08:15:17. Version ac04

Copyright 2017 A. Danko


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