Broad Pass MP201 Parking
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Broad Pass MP201 Parking clear sky chart from 2005-11-06 to 2026-02-16.

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 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	14% 16% 6% 12% 6% 5% 5% 4 6% 6% 19%	134916
	Night	7% 14% 6% 13% 7% 6% 5% 4 6% 7% 25%	134730
Transparency	Day	62% 6% 14% 13% 5% 1	134546
	Night	56% 6% 13% 14% 9% 3	134680
Seeing	Day	20% 5% 17% 27% 22% 9%	19805
	Night	13% 3 18% 35% 24% 6%	24008

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	1 12% 7% 14% 5% 4 6% 4 6% 8% 33%	2361
	11th to 20th	Day	2 13% 8% 20% 8% 5% 5% 4 5% 6% 25%	2436
	21st to end	Day	2 15% 5% 10% 6% 6% 5% 3 5% 7% 37%	3678
February	1st to 10th	Day	1 11% 6% 12% 5% 5% 6% 4 5% 8% 37%	1334
	11th to 20th	Day	2 15% 7% 17% 8% 6% 6% 4 6% 8% 22%	1548
	21st to end	Day	1 9% 5% 13% 8% 7% 7% 4 8% 10% 28%	1372
March	1st to 10th	Day	1 12% 8% 18% 8% 7% 6% 4 7% 7% 21%	4378
	11th to 20th	Day	1 11% 6% 23% 8% 7% 5% 4 6% 8% 21%	4628
	21st to end	Day	2 13% 7% 14% 7% 7% 6% 4 6% 7% 26%	5969
April	1st to 10th	Day	2 15% 8% 18% 8% 5% 5% 5% 6% 6% 21%	2512
	11th to 20th	Day	3 13% 7% 14% 7% 5% 5% 5% 5% 6% 30%	2766
	21st to end	Day	4 15% 6% 11% 6% 6% 6% 4 6% 7% 29%	2943
May	1st to 10th	Day	5% 23% 8% 16% 8% 7% 6% 5% 6% 5% 12%	7260
	11th to 20th	Day	6% 19% 6% 13% 8% 5% 6% 4 6% 6% 20%	7570
	21st to end	Day	8% 19% 6% 11% 7% 5% 6% 4 7% 8% 20%	8911
June	1st to 10th	Day	15% 16% 4 10% 6% 5% 7% 4 7% 8% 18%	3605
	11th to 20th	Day	15% 15% 4 9% 6% 6% 4 5% 7% 8% 21%	3860
	21st to end	Day	20% 15% 4 10% 6% 6% 6% 5% 6% 6% 16%	3900
July	1st to 10th	Day	28% 19% 4 9% 5% 4 4 3 5% 5% 15%	8160
	11th to 20th	Day	24% 18% 5% 11% 5% 4 4 4 5% 5% 13%	8160
	21st to end	Day	23% 15% 5% 12% 6% 5% 5% 4 5% 5% 15%	8409
August	1st to 10th	Day	39% 17% 4 9% 4 3 3 2 3 4 11%	5206
	11th to 20th	Day	40% 16% 4 9% 4 4 3 3 4 4 11%	4792
	21st to end	Day	30% 17% 5% 13% 6% 5% 5% 3 4 4 8%	5038
September	1st to 10th	Day	31% 21% 6% 8% 5% 4 4 3 3 4 11%	2542
	11th to 20th	Day	28% 25% 6% 9% 4 3 4 3 3 3 12%	2396
	21st to end	Day	16% 21% 6% 12% 5% 5% 4 4 6% 5% 16%	2132
October	1st to 10th	Day	9% 21% 7% 14% 8% 5% 5% 4 5% 7% 17%	3170
	11th to 20th	Day	5% 13% 3 10% 5% 6% 5% 4 7% 9% 33%	2839
	21st to end	Day	5% 19% 6% 12% 5% 5% 4 3 5% 7% 29%	2647
November	1st to 10th	Day	3 14% 6% 14% 7% 6% 6% 5% 6% 8% 25%	1358
	11th to 20th	Day	4 12% 5% 9% 5% 6% 6% 4 8% 8% 34%	1129
	21st to end	Day	3 15% 5% 14% 8% 7% 7% 6% 7% 6% 21%	954
December	1st to 10th	Day	4 21% 6% 16% 6% 4 5% 3 6% 7% 22%	1350
	11th to 20th	Day	2 12% 7% 20% 9% 7% 5% 5% 6% 8% 20%	1557
	21st to end	Day	8% 6% 14% 7% 6% 7% 4 7% 9% 31%	2046
January	1st to 10th	Night	1 10% 6% 11% 7% 6% 5% 4 6% 7% 37%	10564
	11th to 20th	Night	1 15% 8% 19% 7% 6% 4 3 5% 6% 25%	10482
	21st to end	Night	2 14% 6% 9% 6% 6% 5% 4 6% 6% 36%	10544
February	1st to 10th	Night	1 9% 6% 13% 7% 5% 5% 4 4 7% 38%	3284
	11th to 20th	Night	2 12% 7% 16% 8% 7% 6% 5% 6% 8% 24%	2850
	21st to end	Night	1 9% 6% 16% 10% 7% 6% 4 6% 8% 25%	2255
March	1st to 10th	Night	1 15% 7% 17% 7% 7% 6% 4 6% 7% 23%	5476
	11th to 20th	Night	1 10% 6% 21% 8% 7% 6% 4 7% 8% 22%	5328
	21st to end	Night	2 15% 8% 17% 7% 4 5% 4 5% 7% 25%	4962
April	1st to 10th	Night	2 12% 7% 15% 9% 7% 6% 5% 7% 8% 22%	1885
	11th to 20th	Night	2 13% 5% 11% 6% 7% 5% 6% 8% 9% 29%	1583
	21st to end	Night	4 15% 5% 9% 6% 4 5% 4 6% 8% 36%	1455
May	1st to 10th	Night	6% 24% 8% 14% 8% 6% 6% 4 5% 6% 13%	2720
	11th to 20th	Night	4 17% 5% 11% 6% 6% 6% 4 7% 7% 25%	2333
	21st to end	Night	9% 23% 4 10% 5% 4 4 4 7% 7% 22%	1986
June	1st to 10th	Night	17% 13% 4 9% 7% 5% 8% 4 7% 8% 18%	792
	11th to 20th	Night	17% 11% 2 10% 6% 4 5% 5% 6% 8% 26%	535
	21st to end	Night	20% 10% 4 11% 10% 6% 4 5% 7% 7% 17%	493
July	1st to 10th	Night	32% 14% 2 8% 5% 4 4 3 4 7% 17%	1820
	11th to 20th	Night	22% 21% 4 10% 7% 4 4 3 5% 4 15%	1820
	21st to end	Night	25% 16% 6% 11% 5% 4 4 4 5% 5% 15%	2448
August	1st to 10th	Night	37% 15% 3 8% 5% 3 4 3 4 5% 13%	1954
	11th to 20th	Night	39% 14% 4 9% 4 3 3 3 4 5% 11%	2266
	21st to end	Night	28% 17% 5% 11% 6% 6% 4 3 4 5% 11%	2871
September	1st to 10th	Night	29% 19% 4 9% 6% 3 3 3 4 5% 14%	1855
	11th to 20th	Night	28% 21% 5% 9% 5% 4 4 3 3 4 14%	2004
	21st to end	Night	17% 20% 5% 11% 6% 5% 6% 4 6% 5% 15%	2265
October	1st to 10th	Night	10% 19% 6% 13% 6% 6% 5% 4 8% 8% 15%	4013
	11th to 20th	Night	5% 16% 4 10% 6% 5% 6% 4 7% 9% 28%	4306
	21st to end	Night	6% 16% 5% 13% 5% 5% 5% 4 6% 7% 30%	5154
November	1st to 10th	Night	6% 15% 6% 13% 7% 6% 5% 4 5% 7% 25%	3157
	11th to 20th	Night	3 12% 7% 11% 6% 5% 5% 4 7% 8% 31%	3491
	21st to end	Night	3 14% 6% 15% 8% 6% 6% 5% 7% 7% 25%	3665
December	1st to 10th	Night	4 19% 6% 16% 7% 5% 5% 4 5% 7% 21%	6060
	11th to 20th	Night	1 12% 8% 17% 8% 6% 6% 5% 6% 8% 24%	6880
	21st to end	Night	1 9% 6% 14% 8% 7% 6% 5% 8% 10% 27%	9174

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	47% 6% 8% 12% 13% 13%	2361
	11th to 20th	Day	56% 5% 10% 17% 8% 4	2448
	21st to end	Day	46% 3 8% 17% 19% 6%	3679
February	1st to 10th	Day	43% 6% 11% 18% 14% 8%	1334
	11th to 20th	Day	57% 9% 11% 10% 10% 2	1555
	21st to end	Day	46% 8% 13% 19% 12% 2	1372
March	1st to 10th	Day	58% 3 9% 14% 11% 4	4378
	11th to 20th	Day	53% 4 10% 13% 19% 1	4628
	21st to end	Day	50% 7% 10% 17% 13% 3	5969
April	1st to 10th	Day	59% 6% 15% 12% 7%	2512
	11th to 20th	Day	51% 8% 15% 17% 8%	2766
	21st to end	Day	49% 6% 14% 24% 6%	2943
May	1st to 10th	Day	66% 6% 11% 16% 1	7260
	11th to 20th	Day	57% 8% 15% 17% 2	7573
	21st to end	Day	59% 7% 17% 15% 1	8912
June	1st to 10th	Day	61% 11% 16% 10% 2	3605
	11th to 20th	Day	60% 9% 17% 13% 1	3860
	21st to end	Day	66% 10% 18% 6%	3900
July	1st to 10th	Day	70% 5% 19% 6%	8071
	11th to 20th	Day	70% 5% 16% 9%	8061
	21st to end	Day	70% 4 15% 11%	8172
August	1st to 10th	Day	77% 6% 12% 6%	5187
	11th to 20th	Day	76% 5% 9% 9% 1	4840
	21st to end	Day	77% 5% 11% 6%	5037
September	1st to 10th	Day	77% 5% 10% 7% 1	2542
	11th to 20th	Day	78% 6% 8% 7% 1	2396
	21st to end	Day	69% 8% 11% 10% 2	2132
October	1st to 10th	Day	64% 5% 11% 18% 2	3170
	11th to 20th	Day	48% 6% 18% 25% 3 1	2839
	21st to end	Day	55% 7% 15% 20% 3	2647
November	1st to 10th	Day	54% 10% 15% 13% 5% 3	1358
	11th to 20th	Day	45% 8% 19% 21% 6% 1	1129
	21st to end	Day	56% 8% 13% 13% 10%	954
December	1st to 10th	Day	61% 5% 11% 14% 8% 1	1350
	11th to 20th	Day	61% 5% 19% 8% 7% 1	1560
	21st to end	Day	46% 6% 17% 13% 13% 5%	2046
January	1st to 10th	Night	44% 5% 11% 13% 14% 12%	10564
	11th to 20th	Night	56% 7% 11% 12% 11% 3	10532
	21st to end	Night	45% 3 9% 19% 18% 7%	10544
February	1st to 10th	Night	46% 5% 10% 17% 15% 8%	3284
	11th to 20th	Night	56% 8% 11% 11% 12% 2	2854
	21st to end	Night	53% 7% 12% 15% 12% 1	2255
March	1st to 10th	Night	59% 3 10% 13% 12% 4	5476
	11th to 20th	Night	56% 5% 9% 13% 16% 1	5330
	21st to end	Night	57% 5% 8% 15% 12% 3	4962
April	1st to 10th	Night	55% 9% 16% 14% 6% 1	1885
	11th to 20th	Night	46% 9% 19% 19% 6%	1583
	21st to end	Night	44% 6% 16% 28% 5%	1455
May	1st to 10th	Night	66% 7% 10% 15% 1	2717
	11th to 20th	Night	53% 9% 16% 19% 3	2333
	21st to end	Night	58% 7% 18% 15% 1	1986
June	1st to 10th	Night	58% 12% 19% 10% 1	792
	11th to 20th	Night	53% 12% 22% 12% 2	535
	21st to end	Night	61% 12% 21% 5%	493
July	1st to 10th	Night	66% 6% 22% 6%	1800
	11th to 20th	Night	69% 6% 16% 10%	1796
	21st to end	Night	71% 5% 18% 6%	2381
August	1st to 10th	Night	71% 6% 19% 3 1	1948
	11th to 20th	Night	75% 4 14% 7%	2284
	21st to end	Night	77% 6% 11% 5%	2871
September	1st to 10th	Night	74% 7% 11% 7%	1855
	11th to 20th	Night	76% 6% 9% 8% 1	2004
	21st to end	Night	69% 8% 13% 9% 2	2265
October	1st to 10th	Night	61% 5% 14% 16% 4	4013
	11th to 20th	Night	52% 4 15% 24% 4	4306
	21st to end	Night	54% 5% 16% 20% 4	5154
November	1st to 10th	Night	57% 8% 14% 16% 6% 1	3157
	11th to 20th	Night	48% 8% 18% 19% 6%	3491
	21st to end	Night	55% 8% 13% 12% 11% 1	3665
December	1st to 10th	Night	60% 5% 8% 17% 9% 1	6060
	11th to 20th	Night	57% 5% 18% 11% 5% 3	6876
	21st to end	Night	49% 6% 16% 11% 13% 4	9174

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	3 2 22% 41% 25% 8%	110
	11th to 20th	Day	5% 4 18% 45% 23% 6%	136
	21st to end	Day	7% 4 18% 40% 24% 6%	352
February	1st to 10th	Day	5% 3 18% 40% 22% 13%	320
	11th to 20th	Day	10% 6% 18% 38% 19% 9%	384
	21st to end	Day	4 3 18% 49% 23% 4	331
March	1st to 10th	Day	6% 3 21% 41% 22% 8%	400
	11th to 20th	Day	3 5% 21% 32% 29% 11%	443
	21st to end	Day	7% 6% 22% 29% 25% 11%	660
April	1st to 10th	Day	7% 9% 25% 31% 20% 7%	636
	11th to 20th	Day	8% 5% 18% 31% 25% 12%	690
	21st to end	Day	9% 3 15% 28% 32% 12%	700
May	1st to 10th	Day	12% 5% 20% 26% 26% 10%	703
	11th to 20th	Day	11% 6% 18% 26% 29% 10%	748
	21st to end	Day	16% 6% 17% 26% 24% 10%	1006
June	1st to 10th	Day	21% 7% 16% 24% 23% 9%	935
	11th to 20th	Day	19% 5% 16% 25% 25% 11%	1130
	21st to end	Day	23% 7% 15% 21% 24% 10%	1083
July	1st to 10th	Day	25% 7% 15% 27% 20% 6%	916
	11th to 20th	Day	34% 5% 16% 22% 15% 8%	912
	21st to end	Day	31% 5% 16% 19% 19% 9%	935
August	1st to 10th	Day	41% 7% 15% 18% 13% 7%	726
	11th to 20th	Day	39% 8% 18% 18% 13% 4	715
	21st to end	Day	39% 6% 16% 20% 13% 5%	803
September	1st to 10th	Day	39% 5% 18% 19% 14% 5%	672
	11th to 20th	Day	39% 6% 18% 18% 13% 5%	616
	21st to end	Day	31% 5% 15% 19% 19% 11%	420
October	1st to 10th	Day	25% 7% 18% 25% 17% 7%	420
	11th to 20th	Day	13% 2 19% 28% 25% 13%	420
	21st to end	Day	16% 3 14% 29% 28% 10%	462
November	1st to 10th	Day	10% 1 18% 32% 27% 11%	381
	11th to 20th	Day	9% 2 16% 30% 34% 10%	189
	21st to end	Day	7% 19% 46% 16% 11%	110
December	1st to 10th	Day	8% 3 24% 42% 18% 5%	110
	11th to 20th	Day	3 4 26% 43% 16% 8%	110
	21st to end	Day	5% 7% 22% 44% 16% 7%	121
January	1st to 10th	Night	5% 3 21% 39% 24% 9%	1060
	11th to 20th	Night	7% 3 25% 41% 18% 6%	1060
	21st to end	Night	8% 4 23% 43% 19% 3	1082
February	1st to 10th	Night	4 4 24% 39% 23% 6%	950
	11th to 20th	Night	6% 4 25% 43% 19% 3	909
	21st to end	Night	5% 2 20% 45% 23% 5%	688
March	1st to 10th	Night	5% 2 20% 48% 21% 3	700
	11th to 20th	Night	3 2 16% 42% 32% 4	700
	21st to end	Night	6% 4 17% 34% 30% 8%	660
April	1st to 10th	Night	6% 4 22% 39% 24% 6%	600
	11th to 20th	Night	7% 4 16% 34% 31% 8%	593
	21st to end	Night	9% 2 12% 29% 40% 8%	568
May	1st to 10th	Night	10% 5% 13% 30% 32% 10%	400
	11th to 20th	Night	11% 3 16% 29% 34% 6%	267
	21st to end	Night	17% 4 13% 26% 35% 5%	217
June	1st to 10th	Night	19% 5% 11% 28% 35% 3	200
	11th to 20th	Night	22% 4 9% 27% 34% 5%	200
	21st to end	Night	23% 2 10% 22% 37% 7%	200
July	1st to 10th	Night	22% 5% 10% 28% 32% 5%	195
	11th to 20th	Night	28% 5% 12% 22% 28% 5%	194
	21st to end	Night	29% 4 13% 18% 30% 6%	344
August	1st to 10th	Night	37% 3 12% 21% 24% 4	398
	11th to 20th	Night	37% 4 13% 20% 23% 3	486
	21st to end	Night	35% 4 12% 22% 22% 6%	660
September	1st to 10th	Night	40% 4 13% 20% 19% 4	600
	11th to 20th	Night	38% 3 13% 22% 20% 5%	600
	21st to end	Night	26% 4 15% 25% 26% 5%	636
October	1st to 10th	Night	26% 4 17% 28% 21% 5%	764
	11th to 20th	Night	17% 3 14% 32% 27% 7%	910
	21st to end	Night	14% 2 16% 36% 27% 5%	1001
November	1st to 10th	Night	12% 3 19% 39% 23% 5%	930
	11th to 20th	Night	8% 3 17% 40% 25% 7%	950
	21st to end	Night	8% 3 23% 38% 23% 6%	1000
December	1st to 10th	Night	12% 4 21% 35% 23% 6%	1060
	11th to 20th	Night	5% 4 22% 42% 22% 6%	1060
	21st to end	Night	6% 4 25% 37% 22% 6%	1166

Page generated at 2026-02-12 21:42:17. Version ac07

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