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 2024-11-30.

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	15% 16% 6% 12% 6% 5% 5% 4 5% 6% 19%	107421
	Night	8% 14% 6% 13% 7% 6% 5% 4 6% 7% 25%	100793
Transparency	Day	62% 8% 13% 12% 4 1	107101
	Night	56% 7% 14% 14% 7% 2	100760
Seeing	Day	20% 6% 17% 27% 21% 9%	18340
	Night	13% 3 18% 35% 25% 6%	22282

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 8% 5% 14% 7% 5% 7% 5% 8% 12% 27%	1269
	11th to 20th	Day	2 11% 6% 15% 7% 5% 4 5% 6% 8% 31%	1294
	21st to end	Day	2 10% 5% 10% 9% 7% 5% 4 6% 9% 35%	1975
February	1st to 10th	Day	1 12% 7% 13% 5% 5% 6% 4 4 7% 36%	1206
	11th to 20th	Day	2 15% 7% 16% 8% 6% 6% 4 6% 8% 22%	1431
	21st to end	Day	1 9% 5% 12% 8% 7% 7% 4 8% 10% 29%	1305
March	1st to 10th	Day	2 12% 9% 20% 8% 6% 5% 3 4 5% 27%	3046
	11th to 20th	Day	1 13% 5% 16% 7% 6% 5% 4 6% 9% 26%	3240
	21st to end	Day	3 19% 9% 17% 7% 6% 5% 4 5% 6% 19%	4165
April	1st to 10th	Day	2 15% 8% 17% 8% 5% 5% 5% 6% 6% 22%	2386
	11th to 20th	Day	3 13% 7% 13% 7% 5% 5% 5% 5% 6% 31%	2626
	21st to end	Day	4 15% 6% 11% 6% 5% 6% 4 6% 8% 30%	2795
May	1st to 10th	Day	5% 22% 8% 14% 7% 6% 6% 5% 7% 6% 13%	5070
	11th to 20th	Day	4 15% 6% 13% 8% 5% 7% 5% 7% 7% 23%	5275
	21st to end	Day	9% 16% 5% 10% 6% 5% 6% 5% 7% 8% 23%	6205
June	1st to 10th	Day	15% 15% 4 9% 6% 5% 7% 5% 7% 8% 18%	3425
	11th to 20th	Day	16% 15% 4 10% 6% 6% 4 5% 7% 7% 19%	3667
	21st to end	Day	21% 15% 4 10% 6% 6% 6% 5% 6% 6% 16%	3706
July	1st to 10th	Day	33% 20% 4 9% 5% 4 4 3 4 5% 11%	5700
	11th to 20th	Day	29% 18% 5% 10% 5% 4 4 3 4 5% 13%	5700
	21st to end	Day	23% 15% 5% 12% 6% 5% 4 3 5% 5% 17%	5859
August	1st to 10th	Day	39% 17% 4 9% 4 3 3 2 3 4 11%	5046
	11th to 20th	Day	40% 16% 4 9% 4 4 3 3 4 4 10%	4643
	21st to end	Day	29% 17% 5% 13% 6% 5% 5% 3 5% 4 8%	4884
September	1st to 10th	Day	29% 21% 6% 8% 5% 4 4 3 4 4 12%	2415
	11th to 20th	Day	28% 25% 6% 9% 4 3 4 3 3 3 13%	2276
	21st to end	Day	16% 21% 5% 11% 5% 5% 4 4 6% 5% 17%	2026
October	1st to 10th	Day	8% 21% 7% 14% 8% 5% 5% 4 6% 7% 17%	3073
	11th to 20th	Day	5% 13% 3 10% 5% 6% 5% 4 7% 9% 33%	2752
	21st to end	Day	5% 20% 6% 12% 5% 5% 4 3 5% 7% 29%	2565
November	1st to 10th	Day	3 14% 5% 14% 7% 5% 6% 5% 6% 9% 25%	1292
	11th to 20th	Day	4 12% 5% 9% 5% 6% 6% 4 8% 8% 34%	1075
	21st to end	Day	3 16% 5% 13% 8% 7% 7% 6% 7% 6% 21%	905
December	1st to 10th	Day	4 16% 5% 17% 8% 6% 6% 3 7% 8% 19%	760
	11th to 20th	Day	1 13% 7% 23% 9% 7% 6% 5% 5% 7% 17%	967
	21st to end	Day	10% 6% 15% 7% 7% 8% 4 8% 10% 25%	1397
January	1st to 10th	Night	1 8% 5% 11% 8% 6% 6% 6% 8% 10% 31%	5686
	11th to 20th	Night	2 11% 6% 16% 7% 5% 4 4 5% 7% 33%	5614
	21st to end	Night	2 11% 5% 11% 7% 6% 6% 5% 7% 7% 34%	5695
February	1st to 10th	Night	1 10% 7% 14% 7% 5% 4 3 4 6% 38%	2972
	11th to 20th	Night	2 12% 7% 16% 8% 7% 6% 5% 6% 8% 23%	2636
	21st to end	Night	1 10% 6% 16% 10% 7% 6% 4 6% 7% 26%	2146
March	1st to 10th	Night	1 14% 7% 17% 6% 5% 4 4 5% 7% 31%	3808
	11th to 20th	Night	1 13% 5% 15% 6% 6% 6% 5% 8% 9% 26%	3716
	21st to end	Night	3 20% 10% 18% 6% 4 5% 3 5% 5% 20%	3466
April	1st to 10th	Night	3 12% 7% 15% 9% 7% 6% 5% 7% 8% 22%	1791
	11th to 20th	Night	2 12% 5% 10% 6% 7% 5% 6% 8% 9% 31%	1503
	21st to end	Night	4 15% 4 8% 6% 4 5% 5% 6% 7% 37%	1383
May	1st to 10th	Night	4 22% 9% 14% 7% 6% 6% 4 6% 5% 16%	1900
	11th to 20th	Night	3 14% 5% 11% 7% 7% 7% 5% 7% 8% 26%	1624
	21st to end	Night	9% 17% 3 10% 5% 4 5% 5% 7% 8% 26%	1381
June	1st to 10th	Night	17% 12% 3 9% 7% 5% 8% 5% 7% 8% 19%	753
	11th to 20th	Night	18% 12% 2 10% 6% 5% 5% 5% 6% 9% 23%	508
	21st to end	Night	20% 10% 3 11% 10% 6% 4 5% 7% 7% 18%	468
July	1st to 10th	Night	36% 15% 3 9% 6% 4 4 2 4 6% 12%	1270
	11th to 20th	Night	27% 21% 4 10% 6% 3 4 3 4 4 15%	1270
	21st to end	Night	22% 15% 5% 11% 6% 4 5% 4 5% 6% 17%	1707
August	1st to 10th	Night	38% 15% 3 8% 5% 3 4 3 4 5% 12%	1894
	11th to 20th	Night	40% 13% 4 9% 4 4 3 3 4 5% 12%	2195
	21st to end	Night	27% 17% 5% 11% 6% 6% 4 3 5% 5% 11%	2783
September	1st to 10th	Night	27% 19% 5% 9% 7% 4 3 3 4 5% 15%	1762
	11th to 20th	Night	29% 21% 5% 9% 5% 3 4 3 3 3 14%	1904
	21st to end	Night	16% 19% 5% 11% 6% 5% 6% 4 6% 5% 16%	2152
October	1st to 10th	Night	9% 18% 6% 13% 7% 6% 5% 4 8% 8% 16%	3890
	11th to 20th	Night	5% 16% 4 10% 6% 5% 6% 4 7% 9% 29%	4174
	21st to end	Night	6% 15% 6% 13% 5% 5% 5% 4 6% 7% 30%	4994
November	1st to 10th	Night	6% 15% 6% 12% 7% 6% 5% 4 5% 7% 25%	3003
	11th to 20th	Night	3 13% 6% 11% 6% 5% 5% 4 7% 8% 31%	3325
	21st to end	Night	3 14% 6% 14% 8% 6% 6% 5% 7% 7% 25%	3490
December	1st to 10th	Night	4 17% 8% 16% 7% 5% 4 4 6% 7% 21%	3420
	11th to 20th	Night	1 11% 8% 21% 10% 7% 6% 5% 5% 6% 19%	4240
	21st to end	Night	2 11% 5% 15% 9% 7% 6% 5% 8% 10% 23%	6270

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	45% 12% 14% 18% 7% 4	1269
	11th to 20th	Day	50% 5% 15% 17% 6% 6%	1306
	21st to end	Day	44% 5% 10% 8% 23% 10%	1975
February	1st to 10th	Day	45% 6% 10% 17% 14% 8%	1206
	11th to 20th	Day	56% 10% 12% 10% 10% 2	1438
	21st to end	Day	45% 9% 14% 19% 12% 2	1305
March	1st to 10th	Day	58% 4 9% 10% 12% 6%	3046
	11th to 20th	Day	46% 6% 14% 14% 18% 1	3240
	21st to end	Day	61% 10% 12% 8% 8% 2	4165
April	1st to 10th	Day	58% 7% 15% 12% 8%	2386
	11th to 20th	Day	50% 9% 16% 17% 9%	2626
	21st to end	Day	48% 7% 15% 24% 7%	2795
May	1st to 10th	Day	63% 9% 15% 12% 1	5070
	11th to 20th	Day	50% 12% 18% 18% 2	5278
	21st to end	Day	56% 10% 14% 19% 2	6206
June	1st to 10th	Day	60% 12% 17% 10% 2	3425
	11th to 20th	Day	63% 9% 15% 12% 1	3667
	21st to end	Day	66% 10% 17% 6%	3706
July	1st to 10th	Day	75% 7% 13% 5%	5611
	11th to 20th	Day	72% 5% 11% 11%	5601
	21st to end	Day	67% 6% 15% 12% 1	5673
August	1st to 10th	Day	77% 6% 11% 6%	5027
	11th to 20th	Day	76% 5% 9% 9% 1	4691
	21st to end	Day	77% 5% 11% 7%	4883
September	1st to 10th	Day	76% 6% 11% 7% 1	2415
	11th to 20th	Day	78% 6% 8% 6% 1	2276
	21st to end	Day	68% 8% 12% 10% 2	2026
October	1st to 10th	Day	63% 5% 12% 18% 2	3073
	11th to 20th	Day	47% 6% 18% 25% 3 1	2752
	21st to end	Day	55% 7% 14% 21% 3	2565
November	1st to 10th	Day	54% 10% 15% 13% 5% 3	1292
	11th to 20th	Day	45% 9% 19% 21% 5% 1	1075
	21st to end	Day	57% 9% 13% 11% 10% 1	905
December	1st to 10th	Day	62% 8% 8% 11% 9% 1	760
	11th to 20th	Day	65% 6% 14% 9% 6% 1	970
	21st to end	Day	49% 8% 14% 10% 13% 6%	1397
January	1st to 10th	Night	44% 9% 18% 19% 6% 4	5686
	11th to 20th	Night	49% 9% 13% 15% 9% 5%	5664
	21st to end	Night	45% 5% 10% 9% 19% 12%	5695
February	1st to 10th	Night	48% 5% 8% 15% 15% 8%	2972
	11th to 20th	Night	56% 8% 12% 11% 10% 2	2640
	21st to end	Night	53% 7% 12% 14% 13% 1	2146
March	1st to 10th	Night	54% 4 10% 12% 14% 6%	3808
	11th to 20th	Night	48% 6% 14% 15% 16% 1	3718
	21st to end	Night	63% 8% 12% 8% 8% 2	3466
April	1st to 10th	Night	55% 9% 15% 13% 7% 1	1791
	11th to 20th	Night	45% 10% 20% 19% 6%	1503
	21st to end	Night	44% 6% 16% 28% 6%	1383
May	1st to 10th	Night	63% 10% 14% 12% 1	1900
	11th to 20th	Night	49% 12% 15% 22% 2	1624
	21st to end	Night	51% 10% 16% 21% 2	1381
June	1st to 10th	Night	57% 12% 19% 10% 1	753
	11th to 20th	Night	55% 12% 19% 11% 2	508
	21st to end	Night	62% 13% 20% 6%	468
July	1st to 10th	Night	70% 7% 17% 5%	1250
	11th to 20th	Night	71% 6% 14% 9%	1246
	21st to end	Night	67% 6% 18% 8%	1654
August	1st to 10th	Night	71% 6% 19% 3 1	1888
	11th to 20th	Night	74% 4 14% 7%	2213
	21st to end	Night	76% 6% 11% 5% 1	2783
September	1st to 10th	Night	73% 8% 12% 8%	1762
	11th to 20th	Night	75% 6% 9% 8% 1	1904
	21st to end	Night	68% 8% 13% 10% 2	2152
October	1st to 10th	Night	60% 5% 14% 16% 4	3890
	11th to 20th	Night	51% 5% 15% 25% 4	4174
	21st to end	Night	54% 5% 15% 20% 5%	4994
November	1st to 10th	Night	57% 8% 14% 15% 6% 1	3003
	11th to 20th	Night	49% 8% 19% 19% 6%	3325
	21st to end	Night	54% 8% 13% 11% 12% 1	3490
December	1st to 10th	Night	62% 7% 8% 14% 8% 1	3420
	11th to 20th	Night	63% 8% 11% 11% 6% 1	4236
	21st to end	Night	52% 8% 13% 11% 12% 4	6270

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	2 19% 41% 28% 10%	90
	11th to 20th	Day	5% 3 13% 46% 26% 7%	113
	21st to end	Day	6% 3 17% 42% 25% 7%	308
February	1st to 10th	Day	5% 3 17% 39% 23% 15%	280
	11th to 20th	Day	8% 6% 19% 37% 20% 9%	342
	21st to end	Day	4 3 17% 50% 21% 4	307
March	1st to 10th	Day	6% 3 20% 42% 21% 8%	370
	11th to 20th	Day	4 5% 22% 32% 27% 10%	411
	21st to end	Day	7% 6% 22% 30% 24% 11%	616
April	1st to 10th	Day	6% 10% 25% 30% 21% 8%	592
	11th to 20th	Day	8% 5% 17% 31% 26% 13%	640
	21st to end	Day	9% 3 14% 28% 33% 12%	650
May	1st to 10th	Day	12% 5% 20% 26% 27% 11%	653
	11th to 20th	Day	10% 7% 18% 26% 28% 10%	697
	21st to end	Day	16% 6% 18% 27% 24% 9%	940
June	1st to 10th	Day	19% 7% 16% 24% 24% 10%	875
	11th to 20th	Day	20% 5% 17% 23% 25% 10%	1060
	21st to end	Day	23% 7% 15% 21% 24% 10%	1016
July	1st to 10th	Day	26% 7% 15% 27% 19% 6%	856
	11th to 20th	Day	34% 6% 16% 23% 15% 7%	852
	21st to end	Day	30% 6% 17% 20% 18% 9%	873
August	1st to 10th	Day	41% 8% 16% 18% 12% 6%	676
	11th to 20th	Day	40% 8% 18% 17% 12% 5%	665
	21st to end	Day	37% 6% 16% 21% 14% 5%	748
September	1st to 10th	Day	37% 5% 19% 19% 15% 5%	627
	11th to 20th	Day	40% 7% 19% 17% 11% 5%	576
	21st to end	Day	31% 5% 15% 19% 18% 12%	390
October	1st to 10th	Day	22% 7% 18% 26% 18% 8%	390
	11th to 20th	Day	13% 3 18% 27% 26% 13%	390
	21st to end	Day	17% 3 13% 29% 27% 10%	429
November	1st to 10th	Day	11% 1 17% 33% 26% 12%	355
	11th to 20th	Day	10% 2 17% 28% 34% 10%	175
	21st to end	Day	8% 21% 44% 16% 10%	99
December	1st to 10th	Day	6% 26% 42% 21% 6%	90
	11th to 20th	Day	2 2 21% 48% 17% 10%	90
	21st to end	Day	6% 7% 15% 47% 16% 8%	99
January	1st to 10th	Night	4 2 18% 39% 26% 11%	940
	11th to 20th	Night	7% 2 22% 43% 20% 6%	940
	21st to end	Night	7% 2 22% 45% 20% 3	966
February	1st to 10th	Night	4 4 22% 39% 24% 7%	850
	11th to 20th	Night	6% 4 25% 42% 20% 3	834
	21st to end	Night	5% 2 21% 46% 22% 4	651
March	1st to 10th	Night	5% 2 20% 49% 20% 3	660
	11th to 20th	Night	3 3 17% 42% 30% 5%	660
	21st to end	Night	7% 4 16% 34% 31% 8%	627
April	1st to 10th	Night	6% 4 20% 39% 25% 6%	570
	11th to 20th	Night	7% 4 15% 33% 33% 9%	563
	21st to end	Night	9% 3 12% 29% 39% 8%	540
May	1st to 10th	Night	9% 6% 13% 29% 33% 10%	380
	11th to 20th	Night	9% 3 17% 30% 35% 6%	254
	21st to end	Night	15% 3 14% 27% 35% 5%	206
June	1st to 10th	Night	18% 5% 12% 27% 36% 3	190
	11th to 20th	Night	23% 4 9% 26% 32% 5%	190
	21st to end	Night	23% 2 11% 21% 37% 7%	190
July	1st to 10th	Night	22% 5% 10% 28% 31% 5%	185
	11th to 20th	Night	29% 5% 13% 21% 29% 4	184
	21st to end	Night	28% 4 13% 18% 31% 6%	327
August	1st to 10th	Night	37% 3 12% 21% 23% 3	378
	11th to 20th	Night	37% 5% 13% 19% 22% 3	461
	21st to end	Night	33% 4 12% 22% 23% 6%	627
September	1st to 10th	Night	37% 5% 13% 21% 20% 5%	570
	11th to 20th	Night	38% 3 13% 21% 20% 5%	570
	21st to end	Night	25% 4 15% 24% 26% 5%	603
October	1st to 10th	Night	23% 4 17% 29% 22% 5%	721
	11th to 20th	Night	16% 3 14% 32% 27% 7%	860
	21st to end	Night	15% 2 16% 37% 26% 5%	946
November	1st to 10th	Night	12% 3 19% 39% 22% 5%	880
	11th to 20th	Night	9% 3 18% 39% 25% 7%	900
	21st to end	Night	8% 3 23% 38% 22% 6%	945
December	1st to 10th	Night	11% 3 19% 36% 24% 6%	940
	11th to 20th	Night	5% 2 19% 43% 24% 7%	940
	21st to end	Night	6% 3 21% 38% 24% 7%	1034

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