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 2018-04-23.

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%
15441
17%
49553
15%
15415
57%
15415
25%
31509

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
32%
777
6%
2716
5%
776
35%
776
10%
2155
January16th to endNight
43%
832
7%
2912
7%
832
45%
832
12%
2251
February1st to 15thNight
49%
757
10%
2522
9%
756
52%
756
17%
1784
February16th to endNight
44%
684
17%
2068
14%
684
50%
684
19%
1440
March1st to 15thNight
44%
780
12%
2340
10%
780
48%
780
21%
1595
March16th to endNight
42%
832
16%
2168
9%
832
46%
832
23%
1539
April1st to 15thNight
43%
779
15%
1949
7%
779
47%
779
25%
1386
April16th to endNight
52%
647
20%
1763
12%
647
56%
647
35%
1084
May1st to 15thNight
56%
362
26%
1442
27%
362
67%
362
35%
698
May16th to endNight
60%
374
16%
1496
22%
374
66%
374
26%
851
June1st to 15thNight
54%
360
14%
1440
16%
360
61%
360
31%
724
June16th to endNight
55%
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
69%
716
33%
1949
27%
716
71%
716
47%
1068
October1st to 15thNight
59%
720
21%
2139
20%
720
63%
720
33%
1280
October16th to endNight
54%
768
21%
2448
20%
768
58%
768
25%
1544
November1st to 15thNight
45%
760
13%
2490
12%
760
48%
760
19%
1720
November16th to endNight
42%
780
10%
2730
9%
780
47%
780
15%
1969
December1st to 15thNight
43%
780
8%
2730
8%
780
45%
780
11%
2124
December16th to endNight
34%
832
9%
2912
5%
832
39%
832
11%
2285

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%
49984
Night
9%7%36%5%3445%6%42%
49721
Cloud CoverDay
7%6%35%5%3445%6%46%
49984
Night
9%7%35%5%3445%7%42%
49725
TransparencyDay
36%412%22%17%6%
49655
Night
41%5%12%20%14%5%
49554
SeeingDay
10%7%20%25%23%12%
6080
Night
12%5%18%34%24%3
15453

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%8%35%45%7%16%
1552
16th to endDay
14%15%7%10%9%46%335%17%
1664
February1st to 15thDay
13%12%5%10%8%35%6%35%25%
1669
16th to endDay
8%7%48%7%46%6%7%8%30%
1691
March1st to 15thDay
9%11%36%6%46%6%7%8%29%
1950
16th to endDay
9%6%37%7%47%5%7%7%33%
2405
April1st to 15thDay
7%7%36%6%45%5%7%9%36%
2329
16th to endDay
6%5%25%425%45%8%49%
2311
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
6%3145%3345%7%53%
2010
October1st to 15thDay
8%5%245%2436%7%48%
1818
16th to endDay
10%8%35%5%46%46%9%36%
1776
November1st to 15thDay
10%9%38%7%45%6%6%7%30%
1696
16th to endDay
11%15%5%9%7%46%6%6%6%19%
1560
December1st to 15thDay
11%12%6%10%10%46%5%6%5%21%
1560
16th to endDay
17%12%7%11%8%45%44418%
1664
January1st to 15thNight
15%15%5%10%7%35%45%5%21%
2716
16th to endNight
14%12%5%8%7%45%5%6%6%22%
2912
February1st to 15thNight
10%11%36%5%45%5%5%6%32%
2510
16th to endNight
8%8%47%7%45%5%5%7%34%
2068
March1st to 15thNight
10%7%46%5%45%6%6%8%33%
2340
16th to endNight
7%7%37%6%46%7%8%7%32%
2164
April1st to 15thNight
10%8%37%6%36%5%5%7%35%
1949
16th to endNight
7%425%5%24448%48%
1763
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
431342345%8%57%
1949
October1st to 15thNight
9%425%5%34346%50%
2139
16th to endNight
8%5%36%6%45%5%5%6%42%
2448
November1st to 15thNight
13%8%36%7%45%45%6%34%
2490
16th to endNight
12%11%47%6%46%447%30%
2730
December1st to 15thNight
11%13%6%8%7%36%5%5%6%23%
2730
16th to endNight
16%13%5%8%7%44446%23%
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
16%17%6%9%9%45%447%15%
1552
16th to endDay
15%15%8%10%9%46%43417%
1664
February1st to 15thDay
14%11%5%9%8%45%5%35%24%
1669
16th to endDay
9%8%48%7%36%6%6%8%30%
1691
March1st to 15thDay
12%10%45%5%45%5%7%8%29%
1950
16th to endDay
9%6%37%7%37%6%6%8%32%
2405
April1st to 15thDay
8%7%35%6%36%5%7%9%36%
2329
16th to endDay
7%5%24335%45%9%49%
2311
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%54%
2010
October1st to 15thDay
8%425%6%2445%7%48%
1818
16th to endDay
11%8%25%6%35%5%5%8%35%
1776
November1st to 15thDay
12%10%37%6%36%6%5%7%30%
1696
16th to endDay
13%15%5%10%8%47%5%5%6%18%
1560
December1st to 15thDay
12%14%8%10%8%46%5%5%5%19%
1560
16th to endDay
18%14%7%11%8%35%43418%
1664
January1st to 15thNight
16%15%5%9%7%3445%6%20%
2716
16th to endNight
15%12%6%8%7%45%5%5%6%21%
2912
February1st to 15thNight
11%10%46%5%35%6%5%7%31%
2510
16th to endNight
8%8%47%7%35%46%7%35%
2068
March1st to 15thNight
12%7%46%5%445%6%8%33%
2340
16th to endNight
8%8%36%6%36%7%8%8%31%
2168
April1st to 15thNight
11%8%36%6%35%5%5%7%36%
1949
16th to endNight
7%5%25%5%2345%7%48%
1763
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
5%21442445%8%58%
1949
October1st to 15thNight
9%5%25%5%2435%6%50%
2139
16th to endNight
8%5%26%6%45%45%7%42%
2448
November1st to 15thNight
14%7%36%6%345%5%6%34%
2490
16th to endNight
14%10%37%5%45%5%5%7%29%
2730
December1st to 15thNight
12%15%8%9%6%3445%6%22%
2730
16th to endNight
18%12%5%9%6%45%446%22%
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
67%9%12%8%2
1552
16th to endDay
71%5%12%8%1
1664
February1st to 15thDay
59%7%17%11%4
1669
16th to endDay
47%8%17%19%6%
1691
March1st to 15thDay
49%6%15%20%7%
1950
16th to endDay
46%6%17%22%7%
2405
April1st to 15thDay
41%5%16%24%11%
2329
16th to endDay
32%315%31%14%2
2311
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
29%314%29%17%5%
2010
October1st to 15thDay
33%417%27%14%1
1818
16th to endDay
43%7%18%22%7%
1776
November1st to 15thDay
50%8%17%18%41
1696
16th to endDay
62%8%13%11%4
1560
December1st to 15thDay
63%8%11%12%3
1560
16th to endDay
69%5%11%11%2
1664
January1st to 15thNight
63%7%14%10%3
2716
16th to endNight
60%6%17%12%2
2912
February1st to 15thNight
49%8%20%16%4
2522
16th to endNight
47%6%14%24%6%
2068
March1st to 15thNight
46%5%16%21%8%
2340
16th to endNight
44%8%14%22%9%
2168
April1st to 15thNight
46%5%12%23%10%
1949
16th to endNight
34%412%28%17%3
1763
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%27%23%10%
1949
October1st to 15thNight
35%310%26%22%1
2139
16th to endNight
40%5%12%25%14%1
2448
November1st to 15thNight
48%6%15%20%7%1
2490
16th to endNight
53%6%17%16%5%
2730
December1st to 15thNight
60%7%14%14%2
2730
16th to endNight
61%7%14%12%4
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%112%27%18%7%
90
16th to endDay
23%11%21%21%15%5%
96
February1st to 15thDay
15%10%22%26%17%8%
239
16th to endDay
13%9%24%29%16%5%
286
March1st to 15thDay
19%13%29%21%13%3
330
16th to endDay
16%12%29%24%15%1
352
April1st to 15thDay
12%15%28%23%12%6%
329
16th to endDay
9%12%27%23%16%9%
288
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%414%27%31%14%
315
October1st to 15thDay
12%5%23%27%23%7%
315
16th to endDay
21%9%13%25%21%9%
192
November1st to 15thDay
23%428%30%12%
130
16th to endDay
16%11%21%27%18%4
90
December1st to 15thDay
15%11%18%28%16%8%
90
16th to endDay
18%5%26%36%13%
96
January1st to 15thNight
26%7%16%27%19%3
780
16th to endNight
20%5%12%34%24%2
832
February1st to 15thNight
15%8%15%32%23%3
764
16th to endNight
12%11%20%34%18%2
684
March1st to 15thNight
15%7%22%34%17%2
780
16th to endNight
11%9%27%33%15%1
832
April1st to 15thNight
15%7%24%32%17%2
779
16th to endNight
9%6%25%32%21%4
647
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%36%7%
716
October1st to 15thNight
12%317%37%25%4
720
16th to endNight
10%5%18%33%25%5%
768
November1st to 15thNight
16%8%18%38%16%1
760
16th to endNight
18%7%18%31%19%3
780
December1st to 15thNight
16%6%15%37%20%3
780
16th to endNight
25%5%19%33%15%1
832
Page generated at 2018-04-24 07:03:00. Version ac04

Copyright 2018 A. Danko


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