Palouse Falls Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Palouse Falls Star Party clear sky chart from 2005-11-05 to 2018-01-12.

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
48%
15013
16%
48361
14%
14985
52%
14985
23%
31541

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
31%
760
6%
2661
5%
760
33%
760
8%
2185
January16th to endNight
36%
768
6%
2688
6%
768
38%
768
9%
2147
February1st to 15thNight
43%
701
8%
2359
8%
697
45%
697
14%
1751
February16th to endNight
41%
632
15%
1895
14%
632
45%
632
18%
1364
March1st to 15thNight
41%
720
12%
2160
10%
720
45%
720
20%
1520
March16th to endNight
38%
768
11%
2013
6%
768
40%
768
19%
1485
April1st to 15thNight
41%
719
14%
1799
6%
719
43%
719
24%
1309
April16th to endNight
47%
593
18%
1673
11%
593
51%
593
29%
1078
May1st to 15thNight
53%
384
23%
1465
23%
384
62%
384
32%
747
May16th to endNight
55%
374
13%
1496
18%
374
60%
374
21%
903
June1st to 15thNight
50%
360
10%
1440
11%
360
57%
360
26%
785
June16th to endNight
54%
360
14%
1440
19%
360
59%
360
30%
734
July1st to 15thNight
69%
340
19%
1360
26%
340
76%
340
52%
524
July16th to endNight
74%
376
29%
1416
40%
354
83%
354
62%
475
August1st to 15thNight
80%
362
34%
1434
41%
360
86%
360
55%
538
August16th to endNight
74%
720
34%
1866
21%
720
78%
720
65%
907
September1st to 15thNight
75%
720
34%
1800
19%
720
78%
720
65%
897
September16th to endNight
64%
716
30%
1970
25%
716
66%
716
45%
1097
October1st to 15thNight
54%
720
20%
2109
17%
720
58%
720
33%
1274
October16th to endNight
49%
768
18%
2475
18%
768
52%
768
23%
1587
November1st to 15thNight
41%
760
13%
2470
12%
760
44%
760
17%
1748
November16th to endNight
39%
780
8%
2730
6%
780
43%
780
13%
2028
December1st to 15thNight
40%
780
8%
2730
8%
780
42%
780
11%
2151
December16th to endNight
30%
832
6%
2912
5%
832
34%
832
9%
2307

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
8%6%35%5%3445%6%46%
48997
Night
10%7%36%5%3445%7%40%
48528
Cloud CoverDay
8%6%35%5%2445%6%46%
48997
Night
11%7%36%5%3445%6%41%
48532
TransparencyDay
37%6%12%21%15%5%
48668
Night
42%6%13%19%13%5%
48361
SeeingDay
11%9%23%26%21%7%
5689
Night
15%7%19%32%22%3
15022

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
17%15%5%10%8%445%46%16%
1520
16th to endDay
14%16%8%12%7%45%5%45%15%
1536
February1st to 15thDay
13%12%5%9%6%46%5%46%24%
1504
16th to endDay
10%10%49%7%35%5%47%32%
1579
March1st to 15thDay
12%8%47%7%36%6%5%8%27%
1800
16th to endDay
12%7%38%7%46%7%6%6%28%
2210
April1st to 15thDay
6%6%26%6%46%6%9%9%35%
2149
16th to endDay
7%5%26%43446%7%45%
2286
May1st to 15thDay
5%414435%45%7%51%
2484
16th to endDay
6%436%5%35%6%6%8%42%
2615
June1st to 15thDay
8%425%5%245%5%7%48%
2520
16th to endDay
6%31332435%7%57%
2520
July1st to 15thDay
1112112335%74%
2520
16th to endDay
1111233478%
2657
August1st to 15thDay
21212235%75%
2517
16th to endDay
221323336%70%
2333
September1st to 15thDay
1212212335%73%
2160
16th to endDay
5%415%4235%5%7%54%
1989
October1st to 15thDay
7%3244345%6%7%49%
1848
16th to endDay
10%6%25%435%47%8%39%
1748
November1st to 15thDay
14%8%46%7%445%6%7%29%
1718
16th to endDay
12%14%5%9%8%45%6%5%6%20%
1560
December1st to 15thDay
12%13%7%12%9%5%5%5%45%18%
1560
16th to endDay
19%14%6%11%8%35%5%45%16%
1664
January1st to 15thNight
19%14%5%8%7%45%446%19%
2661
16th to endNight
16%11%6%9%7%45%5%5%7%20%
2688
February1st to 15thNight
13%10%38%7%35%45%7%28%
2347
16th to endNight
10%8%38%6%35%45%7%33%
1895
March1st to 15thNight
11%9%37%6%35%5%6%7%33%
2160
16th to endNight
11%9%35%5%45%7%8%8%29%
2009
April1st to 15thNight
10%7%46%8%35%6%6%7%34%
1799
16th to endNight
6%7%37%5%24448%44%
1673
May1st to 15thNight
6%32432346%7%54%
1464
16th to endNight
5%5%36%7%346%7%8%39%
1496
June1st to 15thNight
8%4235%25%5%5%6%48%
1440
16th to endNight
7%3245%33446%54%
1440
July1st to 15thNight
21211245%7%69%
1440
16th to endNight
11111245%78%
1512
August1st to 15thNight
312212346%73%
1442
16th to endNight
112212345%73%
1866
September1st to 15thNight
1211212336%73%
1800
16th to endNight
5%31432335%8%57%
1970
October1st to 15thNight
8%4245%3345%7%49%
2109
16th to endNight
9%5%35%6%45%45%7%42%
2475
November1st to 15thNight
14%7%47%5%45%45%6%33%
2470
16th to endNight
15%9%48%7%45%5%5%6%26%
2730
December1st to 15thNight
14%10%5%11%8%45%45%7%22%
2730
16th to endNight
19%13%48%6%345%46%20%
2912

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
19%15%5%10%9%335%5%5%17%
1520
16th to endDay
16%14%9%11%6%45%445%16%
1536
February1st to 15thDay
14%11%48%7%46%445%25%
1504
16th to endDay
11%10%5%8%6%35%5%46%31%
1579
March1st to 15thDay
13%9%37%7%47%6%6%7%27%
1800
16th to endDay
13%8%47%7%36%6%6%6%28%
2210
April1st to 15thDay
7%6%36%6%36%6%7%7%36%
2149
16th to endDay
8%6%25%5%3446%7%44%
2286
May1st to 15thDay
6%4145%2445%8%52%
2484
16th to endDay
6%5%26%6%35%6%7%8%42%
2615
June1st to 15thDay
8%425%5%2445%7%48%
2520
16th to endDay
6%313423446%58%
2520
July1st to 15thDay
2212112235%74%
2520
16th to endDay
1111233479%
2657
August1st to 15thDay
22112335%75%
2517
16th to endDay
222322346%70%
2333
September1st to 15thDay
122212246%72%
2160
16th to endDay
6%4143235%47%55%
1989
October1st to 15thDay
8%4145%346%5%7%49%
1848
16th to endDay
10%7%25%4345%6%9%39%
1748
November1st to 15thDay
15%9%36%6%35%5%5%7%29%
1718
16th to endDay
13%14%5%10%8%35%6%46%21%
1560
December1st to 15thDay
13%13%8%12%8%45%5%45%18%
1560
16th to endDay
21%14%7%10%6%3434417%
1664
January1st to 15thNight
21%14%48%7%34445%20%
2661
16th to endNight
17%11%5%9%7%345%5%6%22%
2688
February1st to 15thNight
14%10%37%6%35%45%7%28%
2347
16th to endNight
12%8%47%7%3445%6%34%
1895
March1st to 15thNight
13%8%37%5%35%5%5%6%34%
2160
16th to endNight
12%8%36%6%36%7%7%8%29%
2013
April1st to 15thNight
10%7%46%6%46%5%5%7%35%
1799
16th to endNight
7%8%36%43435%8%43%
1673
May1st to 15thNight
6%31433346%8%53%
1464
16th to endNight
6%6%25%7%35%6%6%9%40%
1496
June1st to 15thNight
9%42443445%6%48%
1440
16th to endNight
7%3145%235%47%53%
1440
July1st to 15thNight
22121235%7%69%
1440
16th to endNight
11211235%78%
1512
August1st to 15thNight
311212346%73%
1442
16th to endNight
112213345%73%
1866
September1st to 15thNight
222112236%73%
1800
16th to endNight
6%41441426%8%56%
1970
October1st to 15thNight
9%42443445%7%49%
2109
16th to endNight
10%5%26%6%35%45%7%42%
2475
November1st to 15thNight
16%8%36%6%35%45%6%32%
2470
16th to endNight
16%10%37%6%35%5%5%6%27%
2730
December1st to 15thNight
16%10%6%10%7%3445%6%24%
2730
16th to endNight
21%12%5%8%5%3445%6%21%
2912

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
68%8%12%8%1
1520
16th to endDay
68%9%13%6%
1536
February1st to 15thDay
56%10%19%10%3
1504
16th to endDay
52%9%11%20%5%
1579
March1st to 15thDay
52%9%16%17%3
1800
16th to endDay
52%9%16%18%3
2210
April1st to 15thDay
41%8%17%23%8%
2149
16th to endDay
36%6%16%24%12%1
2286
May1st to 15thDay
30%5%10%30%20%2
2484
16th to endDay
36%8%15%26%10%2
2619
June1st to 15thDay
34%6%10%25%18%4
2520
16th to endDay
26%49%29%23%6%
2520
July1st to 15thDay
13%26%22%36%18%
2371
16th to endDay
9%26%17%37%25%
2490
August1st to 15thDay
11%37%22%38%17%
2500
16th to endDay
15%48%28%30%13%
2333
September1st to 15thDay
14%39%27%34%12%
2160
16th to endDay
28%5%14%27%17%5%
1989
October1st to 15thDay
31%6%17%28%14%1
1848
16th to endDay
39%8%19%23%7%
1748
November1st to 15thDay
50%10%16%17%31
1718
16th to endDay
60%9%15%11%2
1560
December1st to 15thDay
65%9%12%10%1
1560
16th to endDay
70%7%11%9%1
1664
January1st to 15thNight
66%8%12%9%2
2661
16th to endNight
61%10%15%11%2
2688
February1st to 15thNight
54%8%18%13%5%
2359
16th to endNight
50%7%12%22%5%
1895
March1st to 15thNight
47%7%15%22%7%
2160
16th to endNight
49%8%15%20%6%
2013
April1st to 15thNight
46%8%14%22%8%
1799
16th to endNight
38%5%14%23%14%3
1673
May1st to 15thNight
27%5%10%30%21%4
1465
16th to endNight
38%8%13%25%10%3
1496
June1st to 15thNight
32%6%10%24%21%3
1440
16th to endNight
30%39%24%22%8%
1440
July1st to 15thNight
14%36%19%31%25%
1360
16th to endNight
9%17%13%32%34%
1416
August1st to 15thNight
13%3416%38%23%
1434
16th to endNight
13%38%22%33%19%
1866
September1st to 15thNight
12%37%24%34%18%
1800
16th to endNight
25%413%26%20%9%
1970
October1st to 15thNight
33%5%12%25%20%1
2109
16th to endNight
39%8%14%23%12%1
2475
November1st to 15thNight
51%6%15%20%5%1
2470
16th to endNight
56%7%17%15%3
2730
December1st to 15thNight
60%9%14%13%2
2730
16th to endNight
63%7%15%11%2
2912

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
32%213%18%25%7%
82
16th to endDay
32%310%34%15%3
64
February1st to 15thDay
20%12%19%25%17%4
162
16th to endDay
15%15%28%24%14%2
238
March1st to 15thDay
24%14%35%13%11%
270
16th to endDay
18%17%29%20%12%
288
April1st to 15thDay
10%17%32%22%12%4
269
16th to endDay
13%16%31%20%12%5%
270
May1st to 15thDay
12%13%27%23%18%5%
288
16th to endDay
7%8%20%24%27%11%
330
June1st to 15thDay
9%11%23%29%20%6%
315
16th to endDay
6%9%26%28%18%9%
315
July1st to 15thDay
2220%40%29%3
305
16th to endDay
1319%36%28%11%
327
August1st to 15thDay
2315%27%33%16%
315
16th to endDay
35%13%29%33%14%
332
September1st to 15thDay
3425%26%22%16%
315
16th to endDay
9%6%23%24%31%5%
315
October1st to 15thDay
12%8%24%30%21%3
315
16th to endDay
21%9%15%31%12%9%
164
November1st to 15thDay
28%11%21%25%12%
134
16th to endDay
18%14%25%25%12%3
90
December1st to 15thDay
22%10%22%22%11%12%
90
16th to endDay
31%9%23%21%13%
96
January1st to 15thNight
27%10%15%26%17%3
764
16th to endNight
23%5%13%33%20%2
768
February1st to 15thNight
21%7%16%31%19%3
704
16th to endNight
16%11%20%30%18%1
632
March1st to 15thNight
18%7%25%31%14%2
720
16th to endNight
17%11%27%31%12%1
768
April1st to 15thNight
13%8%27%30%18%1
719
16th to endNight
11%9%25%28%21%3
593
May1st to 15thNight
8%8%23%28%27%3
385
16th to endNight
9%6%19%31%28%4
375
June1st to 15thNight
10%8%25%34%19%2
360
16th to endNight
10%423%34%23%3
360
July1st to 15thNight
5%220%32%35%2
340
16th to endNight
15%15%40%32%3
376
August1st to 15thNight
4111%37%39%6%
362
16th to endNight
3117%33%37%7%
720
September1st to 15thNight
4315%33%33%10%
720
16th to endNight
7%318%29%32%6%
716
October1st to 15thNight
12%5%20%34%24%2
720
16th to endNight
13%6%20%29%24%4
768
November1st to 15thNight
19%8%20%37%13%1
760
16th to endNight
21%8%16%30%19%3
780
December1st to 15thNight
20%7%14%36%16%4
780
16th to endNight
28%8%18%30%12%
832
Page generated at 2018-01-12 19:01:38. Version ac04

Copyright 2018 A. Danko


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