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 2017-09-16.

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
53%
14574
17%
46832
15%
14548
57%
14548
26%
29570

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%
624
20%
1704
12%
624
56%
624
35%
1045
May1st to 15thNight
57%
362
25%
1442
27%
362
67%
362
35%
698
May16th to endNight
59%
374
16%
1496
21%
374
65%
374
26%
851
June1st to 15thNight
54%
360
14%
1440
16%
360
60%
360
31%
724
June16th to endNight
56%
360
17%
1440
22%
360
63%
360
34%
698
July1st to 15thNight
74%
340
20%
1360
32%
340
79%
340
52%
526
July16th to endNight
76%
376
31%
1416
42%
354
85%
354
67%
466
August1st to 15thNight
82%
360
36%
1432
44%
358
88%
358
60%
506
August16th to endNight
80%
745
35%
1891
24%
745
83%
745
68%
929
September1st to 15thNight
79%
720
34%
1800
20%
720
82%
720
67%
887
September16th to endNight
70%
660
33%
1796
26%
660
72%
660
48%
975
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%25%5%3445%7%47%
47947
Night
8%7%35%5%3445%6%43%
47000
Cloud CoverDay
7%6%35%5%35%45%7%47%
47947
Night
9%7%35%5%3445%7%42%
47004
TransparencyDay
36%411%22%17%6%
47618
Night
40%5%12%20%14%6%
46833
SeeingDay
9%7%19%24%24%13%
5419
Night
12%5%18%34%24%4
14586

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%
2256
May1st to 15thDay
5%4145%346%6%7%50%
2508
16th to endDay
6%5%25%6%45%6%6%8%43%
2615
June1st to 15thDay
7%3244345%47%51%
2520
16th to endDay
4414323448%58%
2520
July1st to 15thDay
11222245%75%
2520
16th to endDay
221223478%
2657
August1st to 15thDay
111213235%76%
2520
16th to endDay
2112212336%73%
2309
September1st to 15thDay
111212235%75%
2160
16th to endDay
5%3145%3345%8%54%
1852
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%
1704
May1st to 15thNight
7%32342335%7%55%
1442
16th to endNight
5%426%446%6%7%10%41%
1496
June1st to 15thNight
6%3144345%5%7%51%
1440
16th to endNight
5%32443435%6%56%
1440
July1st to 15thNight
2112112346%70%
1440
16th to endNight
1212235%78%
1512
August1st to 15thNight
211112236%74%
1440
16th to endNight
121212235%75%
1891
September1st to 15thNight
21221223475%
1800
16th to endNight
43342345%8%58%
1796
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%
2256
May1st to 15thDay
44135%25%5%7%7%50%
2508
16th to endDay
5%5%25%6%35%6%6%8%44%
2615
June1st to 15thDay
8%324425%5%47%51%
2520
16th to endDay
5%313324346%59%
2520
July1st to 15thDay
1112112235%75%
2520
16th to endDay
121224378%
2657
August1st to 15thDay
11212345%75%
2520
16th to endDay
222212236%73%
2309
September1st to 15thDay
111212245%75%
2160
16th to endDay
7%21442445%7%55%
1852
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
7%425%5%2346%7%48%
1704
May1st to 15thNight
7%423224447%56%
1442
16th to endNight
5%425%6%46%6%7%9%41%
1496
June1st to 15thNight
6%4244345%5%8%51%
1440
16th to endNight
4424424446%57%
1440
July1st to 15thNight
2212112336%70%
1440
16th to endNight
11112246%78%
1512
August1st to 15thNight
211111246%75%
1440
16th to endNight
11121323475%
1891
September1st to 15thNight
211121332476%
1800
16th to endNight
421342335%8%59%
1796
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
2256
May1st to 15thDay
29%49%31%21%4
2508
16th to endDay
35%5%13%28%14%2
2619
June1st to 15thDay
32%49%26%22%4
2520
16th to endDay
24%28%31%24%8%
2520
July1st to 15thDay
11%2420%39%21%
2371
16th to endDay
11%2415%35%30%
2490
August1st to 15thDay
12%16%22%37%19%
2503
16th to endDay
14%26%28%35%13%
2309
September1st to 15thDay
12%28%26%37%13%
2160
16th to endDay
28%313%30%18%5%
1852
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
33%412%28%17%2
1704
May1st to 15thNight
27%27%28%27%6%
1443
16th to endNight
35%5%12%26%15%3
1496
June1st to 15thNight
29%411%27%22%4
1440
16th to endNight
28%26%26%24%11%
1440
July1st to 15thNight
15%25%18%31%26%
1360
16th to endNight
8%2416%30%38%
1416
August1st to 15thNight
11%2418%37%25%
1432
16th to endNight
13%25%21%34%22%
1891
September1st to 15thNight
13%26%22%33%21%
1800
16th to endNight
23%49%26%24%11%
1796
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%13%27%23%15%10%
270
May1st to 15thDay
7%11%26%24%19%11%
288
16th to endDay
7%416%20%32%17%
330
June1st to 15thDay
7%9%21%23%26%12%
315
16th to endDay
37%20%27%25%14%
315
July1st to 15thDay
1111%28%40%17%
305
16th to endDay
1214%26%33%22%
327
August1st to 15thDay
237%22%33%30%
315
16th to endDay
2310%24%33%26%
332
September1st to 15thDay
3214%25%29%24%
315
16th to endDay
7%314%27%33%13%
258
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%26%32%21%4
624
May1st to 15thNight
9%5%22%32%26%3
363
16th to endNight
7%220%35%29%4
375
June1st to 15thNight
8%426%37%20%3
360
16th to endNight
5%5%29%29%27%2
360
July1st to 15thNight
5%114%41%33%3
340
16th to endNight
1117%43%31%2
376
August1st to 15thNight
3111%37%40%5%
360
16th to endNight
312%36%37%9%
745
September1st to 15thNight
3211%33%39%9%
720
16th to endNight
6%214%33%35%7%
660
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 2017-09-17 09:05:43. Version ac04

Copyright 2017 A. Danko


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