Kennewick-Pasco-Richland
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kennewick-Pasco-Richland clear sky chart from 2005-11-05 to 2017-04-26.

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
52%
14225
17%
45637
15%
14199
56%
14199
25%
29078

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
5%
716
36%
716
11%
1954
January16th to endNight
41%
768
7%
2688
7%
768
43%
768
12%
2071
February1st to 15thNight
47%
697
9%
2324
8%
696
50%
696
17%
1654
February16th to endNight
46%
632
17%
1911
14%
632
51%
632
19%
1330
March1st to 15thNight
43%
720
11%
2160
9%
720
47%
720
21%
1477
March16th to endNight
40%
768
16%
2001
8%
768
45%
768
23%
1426
April1st to 15thNight
45%
719
16%
1799
8%
719
49%
719
26%
1267
April16th to endNight
52%
612
20%
1668
12%
612
56%
612
36%
1022
May1st to 15thNight
56%
332
27%
1322
29%
332
67%
332
36%
638
May16th to endNight
57%
342
13%
1368
17%
342
64%
342
25%
800
June1st to 15thNight
55%
330
15%
1320
16%
330
62%
330
31%
664
June16th to endNight
55%
330
16%
1320
20%
330
62%
330
34%
642
July1st to 15thNight
71%
310
21%
1240
33%
310
77%
310
50%
492
July16th to endNight
75%
348
28%
1304
39%
326
84%
326
65%
438
August1st to 15thNight
80%
330
38%
1312
46%
328
87%
328
60%
468
August16th to endNight
79%
682
33%
1732
22%
682
81%
682
66%
859
September1st to 15thNight
78%
660
36%
1650
21%
660
81%
660
67%
819
September16th to endNight
69%
656
32%
1786
26%
656
72%
656
47%
971
October1st to 15thNight
58%
660
21%
1961
20%
660
62%
660
33%
1187
October16th to endNight
53%
704
19%
2244
18%
704
58%
704
24%
1438
November1st to 15thNight
46%
700
13%
2293
13%
700
50%
700
19%
1582
November16th to endNight
43%
720
9%
2520
8%
720
46%
720
14%
1833
December1st to 15thNight
40%
720
9%
2520
9%
720
42%
720
11%
1948
December16th to endNight
35%
768
8%
2688
5%
768
40%
768
11%
2098

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
7%6%35%5%3445%7%46%
46042
Night
9%7%36%5%3445%6%42%
45805
Cloud CoverDay
7%6%35%5%35%45%7%46%
46042
Night
9%7%36%5%3445%7%42%
45809
TransparencyDay
37%412%22%17%6%
45713
Night
41%5%12%20%14%5%
45638
SeeingDay
10%7%20%25%24%11%
4856
Night
12%6%18%34%24%3
14237

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
15%15%5%11%7%46%5%5%7%16%
1432
16th to endDay
14%15%8%11%9%5%6%33417%
1536
February1st to 15thDay
13%12%6%10%8%35%6%35%24%
1537
16th to endDay
9%7%48%7%46%6%7%9%30%
1562
March1st to 15thDay
10%11%36%6%46%6%7%8%27%
1800
16th to endDay
9%6%37%7%47%5%7%7%33%
2220
April1st to 15thDay
6%6%35%6%45%5%7%9%38%
2149
16th to endDay
6%5%25%425%45%8%48%
2203
May1st to 15thDay
44145%346%6%7%50%
2298
16th to endDay
6%5%25%6%46%6%6%8%41%
2391
June1st to 15thDay
8%3244245%47%51%
2310
16th to endDay
5%414323448%57%
2310
July1st to 15thDay
11222245%74%
2310
16th to endDay
221223478%
2461
August1st to 15thDay
111213235%75%
2310
16th to endDay
2112212336%72%
2116
September1st to 15thDay
111212235%75%
1980
16th to endDay
6%3145%3345%8%54%
1843
October1st to 15thDay
8%5%245%2436%7%48%
1667
16th to endDay
10%8%35%5%46%5%6%9%35%
1628
November1st to 15thDay
10%8%37%7%45%6%6%7%31%
1563
16th to endDay
11%15%410%8%46%6%6%6%18%
1440
December1st to 15thDay
11%13%6%10%9%45%45%5%22%
1440
16th to endDay
16%11%7%12%8%45%44419%
1536
January1st to 15thNight
15%15%5%9%6%35%45%5%22%
2506
16th to endNight
14%12%5%8%7%45%5%6%6%22%
2688
February1st to 15thNight
10%11%47%5%46%5%5%6%32%
2312
16th to endNight
8%8%47%7%45%5%5%7%34%
1911
March1st to 15thNight
10%7%46%6%45%6%6%8%33%
2160
16th to endNight
8%8%37%7%36%7%8%7%32%
1997
April1st to 15thNight
9%8%37%6%36%5%5%7%36%
1799
16th to endNight
7%425%5%2445%8%48%
1668
May1st to 15thNight
6%42342345%7%55%
1322
16th to endNight
5%426%5%5%6%6%8%10%39%
1368
June1st to 15thNight
7%4143345%5%7%52%
1320
16th to endNight
5%32443436%7%54%
1320
July1st to 15thNight
321311235%6%68%
1320
16th to endNight
111212335%77%
1400
August1st to 15thNight
211112236%74%
1320
16th to endNight
121223235%74%
1732
September1st to 15thNight
21221223475%
1650
16th to endNight
43342345%8%58%
1786
October1st to 15thNight
9%5%25%5%34346%49%
1961
16th to endNight
8%5%36%6%45%5%6%6%40%
2244
November1st to 15thNight
13%7%36%7%45%45%5%35%
2293
16th to endNight
12%11%47%6%46%446%30%
2520
December1st to 15thNight
12%14%6%8%7%35%5%5%6%24%
2520
16th to endNight
16%13%5%8%7%4445%7%23%
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
16%15%6%9%9%46%447%15%
1432
16th to endDay
15%15%9%11%9%36%42317%
1536
February1st to 15thDay
15%12%5%9%9%45%5%35%22%
1537
16th to endDay
9%8%47%7%36%6%6%8%30%
1562
March1st to 15thDay
13%10%45%6%46%5%7%8%28%
1800
16th to endDay
9%6%37%7%37%6%6%8%32%
2220
April1st to 15thDay
7%6%25%5%36%5%7%9%38%
2149
16th to endDay
7%5%24335%45%9%48%
2203
May1st to 15thDay
44135%25%5%6%8%50%
2298
16th to endDay
5%426%6%35%6%6%8%42%
2391
June1st to 15thDay
8%324425%5%47%51%
2310
16th to endDay
5%423324347%58%
2310
July1st to 15thDay
1112112236%74%
2310
16th to endDay
121224478%
2461
August1st to 15thDay
11212345%75%
2310
16th to endDay
222212236%72%
2116
September1st to 15thDay
111212245%74%
1980
16th to endDay
7%21442445%7%55%
1843
October1st to 15thDay
8%425%6%3445%7%48%
1667
16th to endDay
11%8%26%6%36%5%6%8%33%
1628
November1st to 15thDay
12%9%37%6%36%6%5%7%30%
1563
16th to endDay
13%15%5%10%8%5%7%45%6%17%
1440
December1st to 15thDay
13%12%7%10%8%46%5%5%5%20%
1440
16th to endDay
17%13%7%11%8%45%43419%
1536
January1st to 15thNight
16%14%5%8%7%35%45%6%21%
2506
16th to endNight
15%12%6%8%7%45%5%5%6%22%
2688
February1st to 15thNight
11%11%47%5%35%7%5%7%30%
2312
16th to endNight
9%8%37%8%35%46%7%35%
1911
March1st to 15thNight
12%7%46%5%445%6%9%33%
2160
16th to endNight
9%8%36%6%36%7%8%8%31%
2001
April1st to 15thNight
10%7%36%6%35%6%5%7%37%
1799
16th to endNight
6%426%5%2345%7%48%
1668
May1st to 15thNight
6%42322445%7%56%
1322
16th to endNight
5%5%25%6%46%6%8%8%39%
1368
June1st to 15thNight
6%42443445%8%52%
1320
16th to endNight
44243245%46%55%
1320
July1st to 15thNight
2212213347%69%
1320
16th to endNight
11112246%77%
1400
August1st to 15thNight
211111346%74%
1320
16th to endNight
211213335%74%
1732
September1st to 15thNight
211121332475%
1650
16th to endNight
421342335%8%58%
1786
October1st to 15thNight
9%5%25%5%24446%49%
1961
16th to endNight
8%5%26%6%45%45%7%40%
2244
November1st to 15thNight
14%7%36%6%35%5%5%6%35%
2293
16th to endNight
14%10%37%6%46%5%47%28%
2520
December1st to 15thNight
13%14%8%8%6%3445%6%23%
2520
16th to endNight
18%12%5%9%6%45%5%46%22%
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
66%8%12%9%2
1432
16th to endDay
72%5%12%8%2
1536
February1st to 15thDay
60%7%16%11%3
1537
16th to endDay
48%8%16%20%6%
1562
March1st to 15thDay
51%6%15%19%7%
1800
16th to endDay
46%6%17%22%6%
2220
April1st to 15thDay
39%5%16%26%11%
2149
16th to endDay
33%315%31%13%2
2203
May1st to 15thDay
29%49%31%22%4
2298
16th to endDay
36%6%14%28%12%2
2395
June1st to 15thDay
31%49%26%22%4
2310
16th to endDay
25%28%32%23%7%
2310
July1st to 15thDay
12%2421%39%20%
2161
16th to endDay
11%25%16%34%29%
2294
August1st to 15thDay
12%16%23%38%17%
2293
16th to endDay
15%26%26%35%14%
2116
September1st to 15thDay
12%27%26%37%13%
1980
16th to endDay
28%313%30%18%5%
1843
October1st to 15thDay
34%417%27%14%1
1667
16th to endDay
44%7%18%21%7%
1628
November1st to 15thDay
49%8%17%19%31
1563
16th to endDay
63%8%13%11%3
1440
December1st to 15thDay
61%8%12%13%3
1440
16th to endDay
68%5%11%12%2
1536
January1st to 15thNight
61%7%15%11%4
2506
16th to endNight
60%6%16%13%2
2688
February1st to 15thNight
50%8%20%16%4
2324
16th to endNight
47%6%14%24%6%
1911
March1st to 15thNight
47%5%16%20%9%1
2160
16th to endNight
45%7%13%23%9%
2001
April1st to 15thNight
45%5%12%24%11%
1799
16th to endNight
34%413%28%17%2
1668
May1st to 15thNight
27%27%27%28%6%
1323
16th to endNight
37%5%13%26%13%2
1368
June1st to 15thNight
29%411%27%22%4
1320
16th to endNight
28%36%28%24%10%
1320
July1st to 15thNight
17%25%20%31%23%
1240
16th to endNight
9%2417%28%37%
1304
August1st to 15thNight
11%2419%39%23%
1312
16th to endNight
13%26%21%34%21%
1732
September1st to 15thNight
13%26%23%33%21%
1650
16th to endNight
23%49%26%24%11%
1786
October1st to 15thNight
36%310%24%22%2
1961
16th to endNight
42%5%12%25%13%1
2244
November1st to 15thNight
48%6%16%20%7%1
2293
16th to endNight
54%7%16%16%4
2520
December1st to 15thNight
60%7%15%14%2
2520
16th to endNight
61%7%15%12%4
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
35%111%18%23%10%
60
16th to endDay
25%7%14%23%21%7%
64
February1st to 15thDay
16%10%19%25%18%9%
197
16th to endDay
15%7%26%28%16%5%
235
March1st to 15thDay
22%14%30%19%11%1
270
16th to endDay
18%13%30%19%16%1
288
April1st to 15thDay
8%15%28%25%14%8%
269
16th to endDay
10%14%24%23%16%10%
254
May1st to 15thDay
7%12%26%25%16%10%
228
16th to endDay
8%317%22%33%14%
266
June1st to 15thDay
7%9%21%20%27%12%
255
16th to endDay
38%23%27%23%14%
255
July1st to 15thDay
1214%28%37%15%
245
16th to endDay
1215%27%31%21%
271
August1st to 15thDay
239%25%33%25%
255
16th to endDay
2412%26%34%20%
268
September1st to 15thDay
3315%26%29%21%
255
16th to endDay
7%314%27%33%12%
255
October1st to 15thDay
14%5%23%25%23%8%
255
16th to endDay
21%8%12%27%22%7%
140
November1st to 15thDay
22%325%32%16%
87
16th to endDay
16%5%20%31%20%6%
60
December1st to 15thDay
21%16%26%30%5%
60
16th to endDay
12%6%20%42%18%
64
January1st to 15thNight
25%8%16%27%19%3
720
16th to endNight
19%5%12%33%25%2
768
February1st to 15thNight
15%9%14%32%25%3
704
16th to endNight
13%11%18%34%19%2
632
March1st to 15thNight
15%8%23%35%16%2
720
16th to endNight
12%10%27%33%14%1
768
April1st to 15thNight
14%6%24%32%18%3
719
16th to endNight
8%6%25%32%21%4
612
May1st to 15thNight
9%5%23%31%26%3
333
16th to endNight
7%320%36%28%3
343
June1st to 15thNight
8%424%37%20%3
330
16th to endNight
5%5%29%29%26%2
330
July1st to 15thNight
5%116%40%31%4
310
16th to endNight
2218%44%30%2
348
August1st to 15thNight
3211%39%37%5%
330
16th to endNight
3113%37%35%9%
682
September1st to 15thNight
3212%33%39%8%
660
16th to endNight
6%214%33%35%7%
656
October1st to 15thNight
12%317%35%26%4
660
16th to endNight
10%5%18%33%25%5%
704
November1st to 15thNight
16%8%17%38%17%1
700
16th to endNight
18%8%17%31%20%4
720
December1st to 15thNight
17%6%16%38%18%1
720
16th to endNight
24%5%19%32%16%1
768
Page generated at 2017-04-27 14:48:47. Version ac04

Copyright 2017 A. Danko


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