Liberty Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Liberty Lake clear sky chart from 2005-11-05 to 2018-10-08.

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%
17134
29%
51091
18%
17088
57%
17088
40%
27543

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
37%
974
32%
2522
13%
970
50%
970
43%
1397
January16th to endNight
38%
1040
37%
2704
14%
1040
52%
1040
46%
1467
February1st to 15thNight
34%
858
26%
2386
11%
854
43%
854
35%
1399
February16th to endNight
30%
684
30%
2050
11%
684
45%
684
32%
1169
March1st to 15thNight
34%
616
28%
2176
16%
616
48%
616
31%
1165
March16th to endNight
29%
624
22%
2288
12%
624
43%
624
27%
1273
April1st to 15thNight
28%
584
26%
2132
13%
584
48%
584
30%
1099
April16th to endNight
35%
579
27%
1736
16%
579
51%
579
35%
986
May1st to 15thNight
35%
585
26%
1755
16%
585
50%
585
34%
1016
May16th to endNight
49%
611
26%
1828
21%
609
60%
609
41%
995
June1st to 15thNight
58%
585
23%
1755
18%
585
66%
585
46%
896
June16th to endNight
61%
585
26%
1755
20%
585
69%
585
53%
850
July1st to 15thNight
74%
555
22%
1665
21%
555
77%
555
44%
887
July16th to endNight
83%
612
30%
1738
34%
579
84%
579
54%
833
August1st to 15thNight
78%
575
28%
1717
31%
572
81%
572
47%
875
August16th to endNight
77%
621
28%
1971
31%
621
79%
621
45%
984
September1st to 15thNight
60%
585
26%
2145
28%
585
65%
585
33%
1128
September16th to endNight
62%
582
34%
2145
29%
582
71%
582
38%
1054
October1st to 15thNight
48%
637
31%
2141
23%
637
56%
637
37%
1126
October16th to endNight
48%
768
38%
2304
19%
768
62%
768
49%
1117
November1st to 15thNight
44%
884
30%
2404
13%
884
55%
884
46%
1282
November16th to endNight
39%
975
34%
2535
15%
975
50%
975
42%
1452
December1st to 15thNight
38%
975
30%
2535
12%
975
50%
975
42%
1452
December16th to endNight
36%
1040
31%
2704
13%
1040
48%
1040
36%
1641

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%42432345%7%52%
52042
Night
8%413323346%57%
51287
Cloud CoverDay
9%42432345%7%52%
52040
Night
8%313323346%57%
51287
TransparencyDay
31%310%26%21%5%
51740
Night
27%310%26%25%8%
51092
SeeingDay
10%6%25%31%20%5%
7141
Night
10%7%30%35%14%1
17135

By Month

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
9%6%13323346%56%
1746
16th to endDay
8%5%23212336%60%
1872
February1st to 15thDay
8%8%24323345%52%
1817
16th to endDay
11%7%35%32233452%
1710
March1st to 15thDay
11%5%335%23447%49%
2112
16th to endDay
13%8%24323345%46%
2288
April1st to 15thDay
10%41442345%6%51%
2146
16th to endDay
14%5%24324446%46%
2496
May1st to 15thDay
14%5%3432345%6%46%
2526
16th to endDay
8%4235%445%5%8%46%
2638
June1st to 15thDay
6%31342346%9%54%
2535
16th to endDay
5%2233235%5%9%55%
2535
July1st to 15thDay
7%313435%5%7%9%47%
2535
16th to endDay
5%312325%5%7%10%54%
2674
August1st to 15thDay
5%3234245%6%9%51%
2486
16th to endDay
6%214435%5%7%8%50%
2579
September1st to 15thDay
13%425%423446%46%
2145
16th to endDay
9%323323346%55%
2145
October1st to 15thDay
10%5%1331223460%
1974
16th to endDay
5%213323335%65%
1920
November1st to 15thDay
8%312312347%62%
1781
16th to endDay
8%413312235%62%
1755
December1st to 15thDay
10%6%2442224455%
1755
16th to endDay
12%8%25%32333450%
1872
January1st to 15thNight
7%413313445%61%
2522
16th to endNight
7%413213235%65%
2704
February1st to 15thNight
10%6%24213335%56%
2376
16th to endNight
12%5%13322346%54%
2050
March1st to 15thNight
8%5%24423346%54%
2176
16th to endNight
12%423323445%51%
2288
April1st to 15thNight
11%21342335%7%54%
2132
16th to endNight
12%414323346%54%
1736
May1st to 15thNight
10%32332445%7%51%
1754
16th to endNight
7%2123245%5%8%54%
1827
June1st to 15thNight
421332345%10%58%
1755
16th to endNight
311232245%11%62%
1755
July1st to 15thNight
4312435%46%10%52%
1755
16th to endNight
311322346%9%61%
1846
August1st to 15thNight
22134247%6%9%54%
1727
16th to endNight
3213325%46%9%56%
1971
September1st to 15thNight
11%424323346%54%
2145
16th to endNight
8%313323346%59%
2145
October1st to 15thNight
10%32332234457%
2141
16th to endNight
6%21221234468%
2304
November1st to 15thNight
6%312312336%63%
2404
16th to endNight
8%5%23222235%60%
2535
December1st to 15thNight
10%423223346%57%
2535
16th to endNight
11%7%23312335%54%
2704

Percentage Cloud Cover SE (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%6%13313345%56%
1746
16th to endDay
8%413312246%60%
1872
February1st to 15thDay
8%8%34323345%52%
1817
16th to endDay
11%7%3432333452%
1710
March1st to 15thDay
11%5%24433446%49%
2112
16th to endDay
13%8%34323335%46%
2286
April1st to 15thDay
10%424433446%51%
2146
16th to endDay
14%5%24324446%46%
2496
May1st to 15thDay
13%5%24423447%46%
2526
16th to endDay
7%5%245%345%6%8%46%
2638
June1st to 15thDay
6%31342346%9%54%
2535
16th to endDay
5%2232245%5%9%55%
2535
July1st to 15thDay
7%313435%6%6%9%47%
2535
16th to endDay
5%212325%47%9%54%
2674
August1st to 15thDay
5%3233245%7%9%51%
2486
16th to endDay
6%214435%5%7%8%50%
2579
September1st to 15thDay
13%424433446%47%
2145
16th to endDay
9%413323346%55%
2145
October1st to 15thDay
10%5%13312235%60%
1974
16th to endDay
5%31331333465%
1920
November1st to 15thDay
7%312312247%61%
1781
16th to endDay
8%413312235%62%
1755
December1st to 15thDay
10%6%24423245%54%
1755
16th to endDay
12%7%35%313335%49%
1872
January1st to 15thNight
7%313313345%60%
2522
16th to endNight
7%313213335%64%
2704
February1st to 15thNight
10%6%24213325%56%
2376
16th to endNight
12%5%23222346%54%
2050
March1st to 15thNight
9%5%2441345%6%54%
2176
16th to endNight
12%5%23323445%51%
2288
April1st to 15thNight
11%213423347%54%
2132
16th to endNight
12%414322346%54%
1736
May1st to 15thNight
10%422334447%51%
1754
16th to endNight
7%2123246%6%8%54%
1827
June1st to 15thNight
431332435%10%58%
1755
16th to endNight
311232235%11%61%
1755
July1st to 15thNight
4213335%47%10%52%
1755
16th to endNight
311331346%9%61%
1846
August1st to 15thNight
22133347%7%8%54%
1727
16th to endNight
32134245%5%9%56%
1971
September1st to 15thNight
10%414423246%54%
2145
16th to endNight
8%313313445%59%
2145
October1st to 15thNight
10%323322345%57%
2141
16th to endNight
5%21221234468%
2304
November1st to 15thNight
6%323322246%62%
2404
16th to endNight
9%424212235%60%
2535
December1st to 15thNight
10%423222246%57%
2535
16th to endNight
12%7%23312245%53%
2704

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
30%29%29%24%4
1747
16th to endDay
27%17%30%26%6%
1872
February1st to 15thDay
34%210%27%20%5%
1818
16th to endDay
36%16%27%21%6%
1710
March1st to 15thDay
36%27%23%21%8%
2112
16th to endDay
40%311%23%17%3
2288
April1st to 15thDay
33%311%26%17%6%
2146
16th to endDay
38%38%25%20%4
2496
May1st to 15thDay
38%310%21%21%3
2526
16th to endDay
35%413%27%17%2
2642
June1st to 15thDay
26%414%30%18%4
2535
16th to endDay
24%5%14%24%25%6%
2535
July1st to 15thDay
30%5%13%30%17%2
2396
16th to endDay
23%413%31%24%2
2519
August1st to 15thDay
27%6%13%25%19%7%
2472
16th to endDay
28%5%12%28%18%5%
2579
September1st to 15thDay
38%47%22%18%7%
2145
16th to endDay
29%37%26%26%5%
2145
October1st to 15thDay
28%210%24%24%8%
1974
16th to endDay
23%27%23%30%10%
1920
November1st to 15thDay
23%29%28%25%10%
1781
16th to endDay
27%16%27%28%9%
1755
December1st to 15thDay
34%110%29%22%2
1755
16th to endDay
39%29%20%22%5%
1872
January1st to 15thNight
25%28%29%29%5%
2522
16th to endNight
24%17%27%29%9%
2704
February1st to 15thNight
33%28%28%20%6%
2386
16th to endNight
32%26%26%23%8%
2050
March1st to 15thNight
31%38%21%23%11%
2176
16th to endNight
35%311%25%18%5%
2288
April1st to 15thNight
29%310%24%23%8%
2132
16th to endNight
31%39%27%20%7%
1736
May1st to 15thNight
32%411%22%22%7%
1755
16th to endNight
26%5%15%29%20%3
1829
June1st to 15thNight
22%415%33%19%4
1755
16th to endNight
18%313%30%25%8%
1755
July1st to 15thNight
25%414%29%23%3
1665
16th to endNight
18%312%29%31%4
1738
August1st to 15thNight
22%315%26%22%8%
1717
16th to endNight
22%412%29%23%7%
1971
September1st to 15thNight
32%28%24%20%11%
2145
16th to endNight
27%26%27%28%8%
2145
October1st to 15thNight
29%211%20%23%12%
2141
16th to endNight
19%25%24%34%12%
2304
November1st to 15thNight
24%29%22%29%11%
2404
16th to endNight
28%16%23%31%9%
2535
December1st to 15thNight
28%211%26%24%6%
2535
16th to endNight
33%29%23%24%7%
2704

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
17%9%37%28%7%
135
16th to endDay
6%17%43%22%7%2
144
February1st to 15thDay
8%15%47%25%3
135
16th to endDay
20%14%47%15%2
120
March1st to 15thDay
14%20%45%17%2
135
16th to endDay
13%18%36%22%6%
144
April1st to 15thDay
17%14%35%30%2
145
16th to endDay
20%11%33%22%9%2
508
May1st to 15thDay
14%11%37%24%10%2
543
16th to endDay
12%6%31%25%18%4
597
June1st to 15thDay
7%423%41%18%4
570
16th to endDay
5%123%41%22%5%
570
July1st to 15thDay
5%113%37%30%11%
550
16th to endDay
5%436%41%11%
595
August1st to 15thDay
7%8%37%38%7%
549
16th to endDay
6%114%35%33%8%
491
September1st to 15thDay
12%28%30%32%13%
180
16th to endDay
14%213%35%25%9%
180
October1st to 15thDay
7%5%30%31%16%7%
157
16th to endDay
411%28%36%15%4
144
November1st to 15thDay
16%337%22%16%4
135
16th to endDay
15%17%37%18%9%1
135
December1st to 15thDay
5%8%56%18%11%
135
16th to endDay
20%15%34%26%2
144
January1st to 15thNight
11%10%37%32%7%
975
16th to endNight
9%10%38%34%6%
1040
February1st to 15thNight
14%11%37%32%4
858
16th to endNight
17%12%37%28%4
684
March1st to 15thNight
12%10%40%31%5%
616
16th to endNight
16%11%38%26%6%
624
April1st to 15thNight
13%13%40%26%4
584
16th to endNight
15%9%37%28%8%
579
May1st to 15thNight
10%7%43%27%10%1
585
16th to endNight
8%5%31%32%20%1
611
June1st to 15thNight
5%326%43%18%1
585
16th to endNight
3128%43%19%2
585
July1st to 15thNight
5%13%47%30%2
555
16th to endNight
47%47%37%3
612
August1st to 15thNight
39%47%35%2
575
16th to endNight
410%43%36%4
621
September1st to 15thNight
13%216%38%26%3
585
16th to endNight
10%220%40%21%4
582
October1st to 15thNight
13%330%32%17%2
637
16th to endNight
8%7%33%36%13%
768
November1st to 15thNight
8%9%34%33%12%1
884
16th to endNight
13%10%34%32%9%
975
December1st to 15thNight
13%10%34%33%8%
975
16th to endNight
16%11%32%33%6%
1040
Page generated at 2018-10-09 09:39:17. Version ac04

Copyright 2018 A. Danko


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