Falls City Starparty
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Falls City Starparty clear sky chart from 2005-11-05 to 2017-09-17.

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
49%
14704
13%
46829
12%
14675
51%
14675
19%
32556

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
34%
717
7%
2506
7%
716
36%
716
9%
2038
January16th to endNight
42%
768
11%
2547
11%
768
44%
768
14%
1919
February1st to 15thNight
38%
697
6%
2288
5%
697
39%
697
10%
1857
February16th to endNight
35%
632
9%
2020
6%
632
39%
632
12%
1555
March1st to 15thNight
35%
720
5%
2013
5%
720
36%
720
11%
1670
March16th to endNight
33%
768
7%
2100
5%
768
34%
768
11%
1744
April1st to 15thNight
37%
719
7%
1799
4%
719
38%
719
16%
1426
April16th to endNight
50%
585
11%
1665
7%
585
52%
585
20%
1188
May1st to 15thNight
50%
421
13%
1501
13%
421
54%
421
22%
939
May16th to endNight
53%
375
10%
1496
12%
374
56%
374
17%
980
June1st to 15thNight
56%
360
9%
1440
13%
360
58%
360
20%
892
June16th to endNight
60%
360
13%
1385
19%
360
64%
360
30%
746
July1st to 15thNight
77%
340
19%
1360
27%
340
81%
340
49%
554
July16th to endNight
83%
405
28%
1443
36%
381
89%
381
64%
513
August1st to 15thNight
86%
538
26%
1611
24%
535
87%
535
58%
732
August16th to endNight
78%
643
32%
1789
23%
643
80%
643
53%
900
September1st to 15thNight
77%
720
29%
1800
19%
720
79%
720
62%
928
September16th to endNight
68%
664
26%
1840
22%
664
70%
664
38%
1091
October1st to 15thNight
55%
660
18%
1980
17%
660
59%
660
29%
1266
October16th to endNight
44%
704
12%
2112
12%
704
45%
704
17%
1542
November1st to 15thNight
39%
700
7%
2406
7%
700
40%
700
11%
1920
November16th to endNight
37%
720
6%
2520
6%
720
39%
720
12%
1928
December1st to 15thNight
34%
720
9%
2520
8%
720
37%
720
11%
1959
December16th to endNight
28%
768
6%
2688
5%
768
29%
768
7%
2269

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
19%11%46%5%24345%31%
47905
Night
19%10%36%5%34445%33%
47000
Cloud CoverDay
15%8%37%7%35%446%33%
47905
Night
14%7%36%6%3445%6%36%
47004
TransparencyDay
52%6%12%16%10%2
47579
Night
49%6%13%17%10%2
46830
SeeingDay
18%11%23%25%16%4
5695
Night
18%6%17%33%22%2
14715

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
32%18%5%6%42323317%
1432
16th to endDay
27%12%47%5%33345%22%
1674
February1st to 15thDay
31%18%5%7%5%3433413%
1576
16th to endDay
26%20%6%9%5%3432315%
1454
March1st to 15thDay
33%17%5%7%7%2432310%
1945
16th to endDay
31%17%5%9%7%3442410%
2123
April1st to 15thDay
24%17%5%10%7%34345%12%
2149
16th to endDay
22%15%5%8%6%44435%18%
2292
May1st to 15thDay
18%11%47%5%2445%7%29%
2448
16th to endDay
20%9%47%5%35%5%6%7%22%
2615
June1st to 15thDay
20%12%5%6%5%2445%6%26%
2520
16th to endDay
12%9%47%5%35%446%36%
2520
July1st to 15thDay
7%414313347%59%
2520
16th to endDay
7%323212335%65%
2627
August1st to 15thDay
43134245%48%57%
2340
16th to endDay
5%5%1432335%8%56%
2411
September1st to 15thDay
4413323446%60%
2160
16th to endDay
15%9%35%5%23346%40%
1823
October1st to 15thDay
20%10%37%6%24445%32%
1650
16th to endDay
21%13%48%6%34436%23%
1760
November1st to 15thDay
32%12%5%7%6%25%345%14%
1450
16th to endDay
27%13%49%7%35%43416%
1440
December1st to 15thDay
27%14%5%7%7%2434317%
1440
16th to endDay
33%16%48%5%2433314%
1536
January1st to 15thNight
29%14%5%8%5%3433417%
2506
16th to endNight
23%12%48%6%24435%23%
2547
February1st to 15thNight
24%15%5%8%6%45%435%16%
2276
16th to endNight
23%13%410%6%3434421%
2020
March1st to 15thNight
27%16%47%7%34325%16%
2013
16th to endNight
27%15%5%9%7%34445%13%
2096
April1st to 15thNight
21%14%48%7%35%445%21%
1799
16th to endNight
15%9%46%7%36%5%48%27%
1665
May1st to 15thNight
10%8%47%6%44437%37%
1501
16th to endNight
15%7%36%7%445%5%9%31%
1496
June1st to 15thNight
15%7%25%5%35%447%38%
1440
16th to endNight
9%7%25%5%2445%6%46%
1385
July1st to 15thNight
431231223470%
1440
16th to endNight
2221122477%
1541
August1st to 15thNight
222223437%69%
1620
16th to endNight
4313312346%64%
1789
September1st to 15thNight
412312336%69%
1800
16th to endNight
10%5%25%424447%48%
1840
October1st to 15thNight
15%7%25%333346%41%
1980
16th to endNight
22%10%47%5%34435%29%
2112
November1st to 15thNight
29%12%47%6%345%3417%
2406
16th to endNight
26%11%48%5%34445%22%
2520
December1st to 15thNight
25%12%47%6%34435%21%
2520
16th to endNight
31%15%48%5%2433315%
2688

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
23%12%7%9%8%46%43415%
1432
16th to endDay
21%7%48%7%46%5%46%21%
1674
February1st to 15thDay
25%13%49%8%46%44415%
1576
16th to endDay
19%14%6%8%9%45%45%416%
1454
March1st to 15thDay
24%13%5%8%7%46%5%4413%
1945
16th to endDay
23%12%410%9%46%446%12%
2123
April1st to 15thDay
18%13%5%8%9%5%6%5%6%5%14%
2149
16th to endDay
17%11%49%7%36%6%5%6%21%
2292
May1st to 15thDay
14%9%46%6%2445%7%33%
2448
16th to endDay
16%7%37%7%46%6%5%7%26%
2615
June1st to 15thDay
16%8%5%7%7%45%45%5%29%
2520
16th to endDay
9%6%37%6%36%45%7%39%
2520
July1st to 15thDay
4213422346%63%
2520
16th to endDay
6%212212235%67%
2627
August1st to 15thDay
3312423347%61%
2340
16th to endDay
4414323347%60%
2411
September1st to 15thDay
3413323446%62%
2160
16th to endDay
12%6%26%5%34346%42%
1823
October1st to 15thDay
15%8%26%8%46%5%5%6%32%
1650
16th to endDay
16%8%48%9%46%5%46%25%
1760
November1st to 15thDay
22%11%5%9%8%36%448%14%
1450
16th to endDay
20%11%410%7%5%6%5%4418%
1440
December1st to 15thDay
21%10%5%10%8%5%5%6%5%416%
1440
16th to endDay
22%12%5%10%9%37%5%5%412%
1536
January1st to 15thNight
22%11%49%7%46%5%45%18%
2506
16th to endNight
18%10%49%6%3445%5%27%
2547
February1st to 15thNight
16%11%49%9%46%45%6%19%
2276
16th to endNight
16%9%49%7%5%5%6%4425%
2020
March1st to 15thNight
18%11%48%7%47%5%5%5%20%
2013
16th to endNight
20%10%48%9%46%5%6%6%18%
2100
April1st to 15thNight
17%10%47%7%45%5%6%6%25%
1799
16th to endNight
12%6%36%7%36%46%8%33%
1665
May1st to 15thNight
9%6%26%5%35%5%5%7%42%
1501
16th to endNight
12%6%25%7%346%6%8%35%
1496
June1st to 15thNight
12%5%27%435%347%43%
1440
16th to endNight
6%6%25%5%34346%51%
1385
July1st to 15thNight
221222233473%
1440
16th to endNight
2111112481%
1541
August1st to 15thNight
112312345%73%
1620
16th to endNight
321231323470%
1789
September1st to 15thNight
311222235%73%
1800
16th to endNight
8%424323448%53%
1840
October1st to 15thNight
12%5%25%42345%7%45%
1980
16th to endNight
16%7%28%6%45%5%5%432%
2112
November1st to 15thNight
21%9%39%7%35%5%6%6%21%
2406
16th to endNight
19%10%37%7%45%5%46%25%
2520
December1st to 15thNight
21%9%47%7%46%45%6%23%
2520
16th to endNight
24%11%5%8%9%45%5%4416%
2688

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
72%5%6%7%5%
1432
16th to endDay
62%6%9%10%6%2
1674
February1st to 15thDay
72%7%8%8%3
1576
16th to endDay
71%5%8%7%6%
1454
March1st to 15thDay
73%5%9%7%3
1945
16th to endDay
73%5%11%7%2
2123
April1st to 15thDay
70%6%11%9%2
2149
16th to endDay
62%8%11%11%41
2292
May1st to 15thDay
50%5%14%18%10%
2448
16th to endDay
56%8%15%15%4
2619
June1st to 15thDay
55%7%15%16%5%
2520
16th to endDay
43%5%20%20%7%2
2520
July1st to 15thDay
23%314%29%22%6%
2371
16th to endDay
19%310%30%27%7%
2462
August1st to 15thDay
21%6%18%30%17%5%
2324
16th to endDay
24%414%29%21%4
2411
September1st to 15thDay
22%412%25%24%10%
2160
16th to endDay
42%5%13%22%12%3
1823
October1st to 15thDay
51%6%12%15%12%2
1650
16th to endDay
60%7%11%11%8%1
1760
November1st to 15thDay
68%8%10%10%2
1450
16th to endDay
68%6%7%7%9%
1440
December1st to 15thDay
68%8%7%9%6%
1440
16th to endDay
74%7%7%6%3
1536
January1st to 15thNight
67%5%9%8%6%1
2506
16th to endNight
59%5%10%11%9%4
2547
February1st to 15thNight
65%6%11%11%3
2288
16th to endNight
61%5%13%11%7%1
2020
March1st to 15thNight
65%6%11%11%4
2013
16th to endNight
65%7%13%10%2
2100
April1st to 15thNight
59%6%17%10%5%
1799
16th to endNight
47%8%17%18%5%1
1665
May1st to 15thNight
41%6%17%23%8%2
1502
16th to endNight
45%8%20%19%5%
1496
June1st to 15thNight
41%7%21%22%6%
1440
16th to endNight
32%425%27%6%2
1385
July1st to 15thNight
16%416%31%24%7%
1360
16th to endNight
9%214%32%30%10%
1443
August1st to 15thNight
14%417%39%16%7%
1611
16th to endNight
19%415%32%22%6%
1789
September1st to 15thNight
14%415%26%26%12%
1800
16th to endNight
31%415%24%16%7%
1840
October1st to 15thNight
38%6%12%23%14%4
1980
16th to endNight
53%6%11%16%10%1
2112
November1st to 15thNight
62%7%12%11%4
2406
16th to endNight
60%6%10%8%11%2
2520
December1st to 15thNight
62%5%10%12%8%
2520
16th to endNight
72%5%8%8%3
2688

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
36%6%20%25%11%
60
16th to endDay
27%9%19%25%12%4
202
February1st to 15thDay
36%15%17%19%11%
236
16th to endDay
30%17%25%19%6%
217
March1st to 15thDay
35%18%25%15%31
270
16th to endDay
35%15%26%15%6%1
288
April1st to 15thDay
20%18%24%20%9%5%
269
16th to endDay
27%17%28%14%8%3
270
May1st to 15thDay
18%21%25%18%13%2
288
16th to endDay
17%11%20%24%18%6%
330
June1st to 15thDay
18%11%24%25%17%2
315
16th to endDay
7%12%27%30%19%3
315
July1st to 15thDay
6%5%18%35%26%7%
305
16th to endDay
5%422%38%23%5%
327
August1st to 15thDay
35%18%39%23%10%
315
16th to endDay
4421%29%31%9%
332
September1st to 15thDay
6%5%25%27%26%9%
315
16th to endDay
11%9%23%33%19%2
260
October1st to 15thDay
20%14%20%25%16%2
255
16th to endDay
23%13%22%26%9%3
272
November1st to 15thDay
27%11%25%28%5%1
70
16th to endDay
30%13%28%10%15%3
60
December1st to 15thDay
48%6%31%11%1
60
16th to endDay
21%10%20%32%14%
64
January1st to 15thNight
30%9%18%25%15%1
720
16th to endNight
23%7%14%31%20%3
768
February1st to 15thNight
23%8%17%29%19%
704
16th to endNight
20%11%23%28%14%
632
March1st to 15thNight
25%10%20%29%12%1
720
16th to endNight
25%9%20%29%13%1
768
April1st to 15thNight
22%9%21%26%18%1
719
16th to endNight
16%6%17%37%20%1
585
May1st to 15thNight
11%5%22%40%18%1
422
16th to endNight
14%416%36%26%1
375
June1st to 15thNight
14%118%41%23%1
360
16th to endNight
9%319%43%23%
360
July1st to 15thNight
3213%45%34%1
340
16th to endNight
2110%47%36%1
405
August1st to 15thNight
3440%44%6%
538
16th to endNight
6%18%39%40%2
643
September1st to 15thNight
4112%36%39%5%
720
16th to endNight
10%212%37%33%3
664
October1st to 15thNight
15%318%33%24%3
660
16th to endNight
21%6%18%27%21%4
704
November1st to 15thNight
25%7%17%35%13%
700
16th to endNight
25%8%19%28%15%1
720
December1st to 15thNight
25%9%19%29%13%1
720
16th to endNight
31%9%19%25%13%
768
Page generated at 2017-09-18 05:38:20. Version ac04

Copyright 2017 A. Danko


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