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 2005-11-06 to 2024-12-02.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	7% 7% 3 6% 4 4 4 3 5% 6% 51%	105564
	Night	9% 8% 3 7% 5% 4 4 4 5% 6% 45%	102737
Transparency	Day	33% 4 11% 22% 19% 10%	105310
	Night	39% 5% 11% 21% 16% 8%	102580
Seeing	Day	9% 8% 20% 26% 24% 14%	14453
	Night	12% 6% 19% 36% 23% 3	23554

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 20% 6% 13% 6% 6% 4 4 5% 6% 16%	2539
	11th to 20th	Day	21% 18% 7% 9% 5% 4 4 4 5% 6% 18%	2540
	21st to end	Day	22% 19% 9% 14% 6% 5% 4 3 3 3 11%	2794
February	1st to 10th	Day	14% 13% 6% 12% 8% 5% 5% 4 4 5% 24%	1650
	11th to 20th	Day	11% 12% 4 9% 5% 6% 5% 5% 4 7% 32%	1732
	21st to end	Day	9% 9% 3 9% 7% 6% 6% 5% 7% 8% 31%	1570
March	1st to 10th	Day	7% 8% 3 6% 5% 5% 5% 5% 8% 10% 38%	3138
	11th to 20th	Day	5% 6% 2 6% 4 4 3 3 5% 6% 55%	3299
	21st to end	Day	9% 8% 3 9% 6% 7% 7% 6% 7% 8% 31%	4150
April	1st to 10th	Day	8% 8% 3 7% 5% 6% 5% 5% 7% 8% 39%	2280
	11th to 20th	Day	6% 7% 2 6% 4 5% 5% 4 6% 8% 46%	2249
	21st to end	Day	6% 6% 2 6% 4 5% 4 4 6% 9% 48%	2432
May	1st to 10th	Day	8% 5% 1 4 3 4 4 3 6% 8% 53%	4414
	11th to 20th	Day	4 3 1 4 3 3 4 3 5% 6% 63%	4377
	21st to end	Day	5% 6% 2 6% 5% 5% 6% 5% 6% 8% 46%	4813
June	1st to 10th	Day	9% 5% 2 6% 5% 4 5% 3 5% 8% 48%	2660
	11th to 20th	Day	6% 4 2 4 4 4 5% 4 5% 7% 55%	2660
	21st to end	Day	3 3 1 3 3 3 3 3 4 6% 68%	2660
July	1st to 10th	Day	1 1 2 2 1 2 2 3 3 83%	4420
	11th to 20th	Day	1 1 1 2 2 1 2 2 3 3 83%	4420
	21st to end	Day	1 1 1 1 2 2 2 2 3 4 81%	4790
August	1st to 10th	Day	3 2 1 3 2 2 2 2 4 5% 74%	4400
	11th to 20th	Day	1 1 1 2 2 2 2 3 4 6% 75%	4062
	21st to end	Day	3 3 1 4 3 2 3 2 4 5% 70%	4180
September	1st to 10th	Day	2 1 2 2 2 3 2 5% 6% 74%	2280
	11th to 20th	Day	4 4 1 4 4 4 4 4 6% 7% 59%	2234
	21st to end	Day	7% 4 1 5% 4 4 3 3 5% 7% 58%	2090
October	1st to 10th	Day	5% 3 1 4 3 3 3 3 4 7% 64%	3221
	11th to 20th	Day	5% 4 2 5% 4 4 6% 5% 7% 11% 47%	3130
	21st to end	Day	10% 7% 2 8% 5% 6% 5% 4 6% 7% 40%	3101
November	1st to 10th	Day	13% 9% 3 9% 6% 5% 5% 5% 6% 7% 33%	1764
	11th to 20th	Day	12% 16% 4 10% 7% 6% 6% 4 6% 6% 25%	1665
	21st to end	Day	11% 14% 6% 14% 8% 7% 5% 5% 5% 6% 20%	1600
December	1st to 10th	Day	10% 15% 6% 13% 9% 7% 5% 5% 5% 5% 21%	1528
	11th to 20th	Day	14% 21% 9% 14% 8% 5% 4 3 4 5% 12%	1928
	21st to end	Day	14% 15% 7% 18% 10% 7% 5% 3 4 4 15%	2794
January	1st to 10th	Night	17% 19% 5% 11% 7% 5% 5% 4 5% 6% 16%	4406
	11th to 20th	Night	18% 16% 5% 9% 5% 4 4 4 7% 7% 20%	4420
	21st to end	Night	17% 17% 8% 14% 6% 5% 4 4 5% 5% 14%	4862
February	1st to 10th	Night	13% 13% 4 8% 5% 5% 6% 5% 5% 7% 30%	2527
	11th to 20th	Night	9% 12% 3 8% 6% 5% 5% 4 6% 7% 35%	2333
	21st to end	Night	9% 10% 4 7% 7% 5% 6% 4 6% 6% 35%	1884
March	1st to 10th	Night	8% 7% 2 6% 4 5% 6% 5% 8% 10% 39%	3736
	11th to 20th	Night	6% 6% 2 5% 4 3 3 4 5% 6% 55%	3676
	21st to end	Night	7% 8% 3 8% 7% 6% 7% 6% 9% 9% 30%	3502
April	1st to 10th	Night	11% 10% 3 7% 5% 4 5% 4 5% 8% 38%	1900
	11th to 20th	Night	9% 6% 3 6% 5% 5% 4 4 5% 6% 48%	1879
	21st to end	Night	6% 5% 2 7% 6% 5% 5% 4 7% 7% 44%	1748
May	1st to 10th	Night	7% 6% 2 5% 4 4 5% 4 6% 7% 51%	2544
	11th to 20th	Night	6% 4 1 3 3 3 4 3 5% 7% 61%	2516
	21st to end	Night	6% 4 2 6% 4 5% 5% 4 7% 9% 49%	2762
June	1st to 10th	Night	8% 5% 1 5% 4 4 6% 4 7% 9% 48%	1520
	11th to 20th	Night	7% 6% 3 5% 5% 4 3 3 5% 6% 54%	1520
	21st to end	Night	3 3 1 4 4 3 4 4 4 5% 64%	1520
July	1st to 10th	Night	1 1 1 1 1 1 2 2 3 4 82%	2540
	11th to 20th	Night	1 1 1 1 1 1 1 2 3 5% 82%	2540
	21st to end	Night	1 1 1 2 1 1 2 2 3 4 82%	2761
August	1st to 10th	Night	4 3 1 3 2 2 2 2 4 5% 71%	2529
	11th to 20th	Night	1 2 1 2 2 3 3 2 4 5% 75%	2772
	21st to end	Night	2 2 1 3 3 3 4 3 4 6% 72%	3498
September	1st to 10th	Night	3 2 1 2 2 2 3 3 3 5% 75%	1900
	11th to 20th	Night	4 3 1 4 4 3 4 3 6% 7% 61%	1945
	21st to end	Night	6% 3 1 4 3 3 5% 2 5% 9% 59%	2090
October	1st to 10th	Night	5% 3 1 3 3 3 3 3 4 5% 67%	3755
	11th to 20th	Night	7% 3 1 5% 3 4 4 4 6% 8% 53%	3806
	21st to end	Night	10% 5% 2 6% 5% 5% 5% 4 7% 8% 45%	4457
November	1st to 10th	Night	14% 8% 3 8% 5% 5% 4 3 5% 6% 37%	2535
	11th to 20th	Night	14% 10% 3 9% 6% 5% 5% 5% 5% 6% 30%	2730
	21st to end	Night	12% 11% 4 8% 6% 7% 6% 4 6% 8% 29%	2800
December	1st to 10th	Night	11% 16% 7% 11% 7% 5% 4 4 5% 6% 24%	2686
	11th to 20th	Night	16% 19% 8% 13% 7% 6% 5% 4 5% 5% 13%	3276
	21st to end	Night	14% 18% 5% 13% 7% 7% 5% 4 4 6% 19%	4862

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	67% 8% 10% 10% 4	2539
	11th to 20th	Day	68% 5% 16% 10% 2	2540
	21st to end	Day	79% 5% 9% 6% 2	2794
February	1st to 10th	Day	59% 7% 18% 11% 5%	1650
	11th to 20th	Day	50% 7% 15% 19% 7%	1741
	21st to end	Day	47% 7% 15% 21% 8% 1	1570
March	1st to 10th	Day	38% 6% 13% 26% 17% 1	3138
	11th to 20th	Day	29% 4 16% 38% 13%	3299
	21st to end	Day	47% 6% 18% 19% 9% 1	4150
April	1st to 10th	Day	40% 6% 15% 23% 15% 2	2280
	11th to 20th	Day	34% 4 14% 26% 15% 6%	2252
	21st to end	Day	33% 3 14% 28% 18% 3	2432
May	1st to 10th	Day	28% 4 7% 30% 24% 5%	4414
	11th to 20th	Day	21% 4 7% 29% 28% 10%	4380
	21st to end	Day	33% 5% 17% 30% 13% 3	4814
June	1st to 10th	Day	34% 4 9% 27% 21% 5%	2660
	11th to 20th	Day	27% 4 11% 29% 24% 5%	2660
	21st to end	Day	19% 2 7% 30% 29% 12%	2660
July	1st to 10th	Day	8% 1 3 13% 26% 48%	4351
	11th to 20th	Day	9% 2 3 8% 24% 54%	4345
	21st to end	Day	9% 2 4 17% 35% 34%	4639
August	1st to 10th	Day	15% 2 4 13% 37% 30%	4384
	11th to 20th	Day	11% 2 4 34% 36% 12%	4104
	21st to end	Day	19% 2 6% 28% 33% 12%	4179
September	1st to 10th	Day	12% 3 8% 29% 33% 16%	2280
	11th to 20th	Day	24% 4 11% 26% 27% 8%	2234
	21st to end	Day	27% 3 15% 33% 17% 4	2090
October	1st to 10th	Day	21% 3 11% 37% 24% 3	3221
	11th to 20th	Day	29% 6% 21% 29% 14% 1	3130
	21st to end	Day	40% 5% 15% 28% 12% 1	3101
November	1st to 10th	Day	49% 7% 16% 20% 7% 1	1764
	11th to 20th	Day	57% 8% 15% 15% 5% 1	1665
	21st to end	Day	63% 7% 15% 11% 5%	1600
December	1st to 10th	Day	63% 7% 13% 13% 5%	1528
	11th to 20th	Day	75% 6% 10% 8% 2	1928
	21st to end	Day	74% 4 10% 10% 2	2794
January	1st to 10th	Night	67% 7% 14% 9% 3	4406
	11th to 20th	Night	62% 5% 18% 14% 2	4420
	21st to end	Night	71% 5% 14% 8% 2	4862
February	1st to 10th	Night	52% 7% 20% 17% 4 1	2527
	11th to 20th	Night	46% 7% 16% 23% 8%	2335
	21st to end	Night	47% 7% 15% 21% 8% 2	1884
March	1st to 10th	Night	37% 6% 12% 30% 14% 1	3736
	11th to 20th	Night	28% 4 13% 37% 18%	3676
	21st to end	Night	44% 8% 17% 23% 7% 1	3502
April	1st to 10th	Night	44% 5% 14% 23% 13% 1	1900
	11th to 20th	Night	37% 4 10% 26% 18% 6%	1879
	21st to end	Night	35% 6% 13% 24% 17% 5%	1748
May	1st to 10th	Night	31% 4 6% 28% 28% 4	2544
	11th to 20th	Night	21% 6% 7% 30% 31% 5%	2516
	21st to end	Night	29% 6% 17% 34% 12% 2	2762
June	1st to 10th	Night	31% 5% 11% 26% 22% 5%	1520
	11th to 20th	Night	30% 5% 7% 29% 24% 5%	1520
	21st to end	Night	22% 3 6% 26% 28% 15%	1520
July	1st to 10th	Night	8% 2 3 13% 24% 50%	2500
	11th to 20th	Night	7% 1 3 10% 22% 56%	2492
	21st to end	Night	9% 1 2 13% 30% 45%	2674
August	1st to 10th	Night	17% 1 2 9% 33% 37%	2521
	11th to 20th	Night	13% 2 4 30% 34% 17%	2796
	21st to end	Night	15% 2 6% 26% 31% 19%	3498
September	1st to 10th	Night	14% 3 7% 23% 32% 22%	1900
	11th to 20th	Night	22% 4 10% 25% 26% 14%	1945
	21st to end	Night	23% 4 10% 30% 25% 9%	2090
October	1st to 10th	Night	21% 2 8% 34% 33% 2	3755
	11th to 20th	Night	29% 4 16% 28% 22% 2	3806
	21st to end	Night	35% 5% 12% 32% 15% 2	4457
November	1st to 10th	Night	46% 7% 14% 23% 9% 1	2535
	11th to 20th	Night	52% 7% 14% 20% 6% 1	2730
	21st to end	Night	51% 8% 17% 17% 6% 1	2800
December	1st to 10th	Night	59% 8% 15% 14% 3	2686
	11th to 20th	Night	72% 7% 12% 7% 2	3276
	21st to end	Night	65% 6% 13% 10% 6%	4862

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	27% 7% 21% 25% 16% 3	180
	11th to 20th	Day	25% 9% 17% 28% 17% 4	180
	21st to end	Day	18% 8% 21% 27% 23% 3	198
February	1st to 10th	Day	18% 12% 24% 27% 15% 5%	310
	11th to 20th	Day	18% 10% 21% 26% 19% 6%	397
	21st to end	Day	14% 11% 25% 27% 19% 4	382
March	1st to 10th	Day	16% 13% 28% 23% 15% 5%	460
	11th to 20th	Day	11% 10% 19% 29% 22% 10%	460
	21st to end	Day	15% 11% 26% 28% 16% 3	506
April	1st to 10th	Day	13% 15% 24% 24% 14% 10%	460
	11th to 20th	Day	9% 13% 30% 25% 14% 8%	452
	21st to end	Day	7% 11% 28% 27% 19% 8%	460
May	1st to 10th	Day	6% 9% 25% 28% 21% 11%	463
	11th to 20th	Day	10% 8% 21% 24% 24% 14%	488
	21st to end	Day	10% 5% 19% 26% 25% 16%	529
June	1st to 10th	Day	9% 8% 19% 22% 26% 16%	490
	11th to 20th	Day	7% 11% 25% 29% 19% 9%	490
	21st to end	Day	2 5% 19% 25% 31% 18%	490
July	1st to 10th	Day	2 2 12% 28% 41% 16%	486
	11th to 20th	Day	1 3 14% 30% 33% 20%	484
	21st to end	Day	1 2 12% 23% 33% 29%	531
August	1st to 10th	Day	3 3 9% 23% 34% 27%	487
	11th to 20th	Day	1 2 10% 23% 30% 32%	477
	21st to end	Day	4 6% 15% 26% 27% 22%	539
September	1st to 10th	Day	3 2 12% 26% 32% 24%	490
	11th to 20th	Day	5% 5% 16% 26% 27% 22%	490
	21st to end	Day	7% 7% 16% 28% 28% 14%	490
October	1st to 10th	Day	10% 5% 20% 25% 24% 16%	490
	11th to 20th	Day	10% 9% 15% 25% 26% 15%	471
	21st to end	Day	18% 8% 21% 30% 14% 8%	330
November	1st to 10th	Day	18% 9% 23% 29% 18% 3	300
	11th to 20th	Day	24% 10% 21% 23% 20% 3	233
	21st to end	Day	9% 12% 19% 29% 27% 6%	200
December	1st to 10th	Day	10% 10% 25% 28% 14% 13%	182
	11th to 20th	Day	17% 9% 22% 33% 17% 2	180
	21st to end	Day	15% 6% 32% 30% 14% 3	198
January	1st to 10th	Night	26% 9% 18% 28% 16% 3	760
	11th to 20th	Night	20% 7% 17% 35% 19% 3	760
	21st to end	Night	18% 6% 14% 37% 23% 3	836
February	1st to 10th	Night	17% 9% 19% 33% 20% 2	760
	11th to 20th	Night	13% 10% 21% 34% 20% 3	744
	21st to end	Night	13% 14% 20% 35% 17% 1	628
March	1st to 10th	Night	13% 8% 23% 35% 19% 3	760
	11th to 20th	Night	10% 9% 19% 35% 23% 3	760
	21st to end	Night	12% 8% 30% 34% 14% 1	836
April	1st to 10th	Night	16% 7% 20% 37% 17% 2	760
	11th to 20th	Night	10% 9% 29% 30% 18% 4	751
	21st to end	Night	8% 8% 27% 35% 21% 2	608
May	1st to 10th	Night	7% 6% 24% 38% 23% 3	384
	11th to 20th	Night	10% 5% 15% 36% 31% 3	374
	21st to end	Night	8% 3 20% 39% 26% 4	411
June	1st to 10th	Night	9% 5% 25% 35% 23% 3	380
	11th to 20th	Night	9% 6% 32% 34% 17% 2	380
	21st to end	Night	2 4 23% 39% 29% 3	380
July	1st to 10th	Night	4 2 18% 45% 29% 2	370
	11th to 20th	Night	4 2 20% 46% 26% 2	368
	21st to end	Night	1 2 17% 41% 35% 4	416
August	1st to 10th	Night	4 2 12% 42% 37% 4	378
	11th to 20th	Night	4 1 13% 35% 38% 10%	534
	21st to end	Night	3 2 14% 41% 34% 6%	836
September	1st to 10th	Night	3 3 15% 39% 36% 5%	760
	11th to 20th	Night	5% 2 12% 34% 38% 8%	760
	21st to end	Night	6% 3 17% 33% 34% 7%	760
October	1st to 10th	Night	10% 3 15% 38% 30% 4	760
	11th to 20th	Night	10% 7% 16% 33% 27% 7%	760
	21st to end	Night	11% 7% 23% 33% 21% 5%	836
November	1st to 10th	Night	16% 7% 20% 36% 19% 1	780
	11th to 20th	Night	18% 10% 21% 32% 17% 2	800
	21st to end	Night	16% 6% 17% 38% 20% 4	800
December	1st to 10th	Night	15% 7% 18% 35% 21% 3	768
	11th to 20th	Night	21% 8% 18% 36% 17% 1	760
	21st to end	Night	24% 7% 19% 36% 13% 1	836

Page generated at 2024-11-29 07:43:09. Version ac07

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