Escure Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Escure Ranch clear sky chart from 2005-11-06 to 2024-03-08.

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	10% 7% 3 6% 5% 3 4 5% 5% 6% 44%	78058
	Night	12% 8% 4 7% 6% 3 5% 5% 5% 6% 39%	81437
Transparency	Day	40% 6% 12% 21% 16% 5%	77784
	Night	44% 7% 12% 19% 13% 5%	81291
Seeing	Day	12% 7% 22% 27% 22% 9%	13331
	Night	15% 5% 20% 35% 21% 3	22932

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	17% 16% 6% 9% 8% 4 6% 6% 5% 5% 18%	2539
	11th to 20th	Day	21% 13% 6% 10% 7% 5% 5% 5% 5% 5% 18%	2516
	21st to end	Day	23% 17% 6% 10% 7% 4 4 4 4 4 17%	2794
February	1st to 10th	Day	16% 13% 5% 8% 6% 3 6% 5% 5% 6% 27%	1567
	11th to 20th	Day	14% 13% 4 9% 7% 4 5% 5% 5% 5% 29%	1769
	21st to end	Day	12% 13% 5% 7% 6% 4 5% 5% 4 6% 32%	1570
March	1st to 10th	Day	12% 11% 4 7% 7% 4 6% 5% 6% 7% 32%	1871
	11th to 20th	Day	12% 9% 4 8% 7% 4 7% 6% 6% 7% 31%	1832
	21st to end	Day	14% 9% 5% 8% 7% 4 6% 6% 6% 8% 27%	2376
April	1st to 10th	Day	10% 9% 3 7% 7% 4 7% 7% 7% 9% 31%	2160
	11th to 20th	Day	8% 7% 3 7% 7% 3 6% 5% 5% 7% 41%	2158
	21st to end	Day	10% 6% 3 6% 5% 3 4 5% 6% 8% 44%	2340
May	1st to 10th	Day	6% 5% 2 5% 5% 3 4 5% 5% 8% 52%	2474
	11th to 20th	Day	9% 6% 3 5% 6% 3 5% 6% 7% 9% 42%	2477
	21st to end	Day	9% 7% 3 6% 6% 3 5% 5% 5% 8% 43%	2723
June	1st to 10th	Day	12% 6% 3 6% 5% 3 6% 4 5% 7% 44%	2520
	11th to 20th	Day	9% 6% 2 4 4 3 4 5% 6% 8% 50%	2520
	21st to end	Day	5% 3 1 3 3 3 3 4 4 7% 64%	2520
July	1st to 10th	Day	2 2 1 2 3 2 3 3 4 5% 73%	2520
	11th to 20th	Day	2 1 1 2 2 2 2 3 4 5% 75%	2520
	21st to end	Day	1 1 1 1 1 1 2 3 2 4 82%	2741
August	1st to 10th	Day	3 2 1 2 2 2 3 3 3 5% 74%	2507
	11th to 20th	Day	3 2 1 2 2 1 2 3 5% 6% 74%	2380
	21st to end	Day	4 3 1 3 3 2 3 5% 5% 7% 65%	2376
September	1st to 10th	Day	3 2 1 3 3 2 3 3 4 5% 72%	2160
	11th to 20th	Day	5% 4 1 4 4 3 4 5% 7% 7% 56%	2077
	21st to end	Day	6% 4 2 5% 4 3 5% 5% 5% 8% 53%	1980
October	1st to 10th	Day	8% 5% 2 5% 5% 3 4 5% 5% 7% 52%	1886
	11th to 20th	Day	10% 4 1 4 5% 3 4 5% 5% 8% 49%	1724
	21st to end	Day	12% 7% 3 6% 5% 3 5% 5% 6% 6% 43%	1782
November	1st to 10th	Day	16% 7% 3 6% 6% 4 5% 6% 6% 8% 34%	1674
	11th to 20th	Day	17% 12% 5% 7% 7% 4 4 6% 5% 6% 28%	1615
	21st to end	Day	13% 12% 6% 11% 7% 3 6% 5% 6% 6% 25%	1520
December	1st to 10th	Day	16% 13% 6% 9% 7% 4 7% 6% 5% 6% 21%	1353
	11th to 20th	Day	18% 13% 8% 15% 10% 4 4 5% 4 4 14%	1723
	21st to end	Day	16% 14% 7% 11% 7% 3 5% 6% 6% 6% 19%	2794
January	1st to 10th	Night	21% 15% 6% 9% 7% 4 6% 4 5% 5% 18%	4406
	11th to 20th	Night	19% 12% 5% 9% 6% 4 5% 4 5% 7% 24%	4382
	21st to end	Night	20% 13% 6% 10% 6% 3 5% 5% 5% 6% 21%	4862
February	1st to 10th	Night	16% 14% 5% 7% 6% 4 5% 5% 5% 6% 29%	2612
	11th to 20th	Night	13% 10% 4 7% 6% 3 5% 6% 5% 7% 35%	2297
	21st to end	Night	12% 10% 5% 8% 7% 4 4 5% 5% 7% 33%	1884
March	1st to 10th	Night	13% 9% 3 6% 7% 4 5% 6% 6% 6% 36%	2249
	11th to 20th	Night	13% 8% 3 6% 7% 3 5% 5% 6% 8% 36%	2122
	21st to end	Night	13% 8% 4 7% 7% 5% 6% 6% 7% 8% 29%	1980
April	1st to 10th	Night	11% 9% 3 7% 7% 4 4 6% 6% 9% 35%	1800
	11th to 20th	Night	9% 7% 4 8% 5% 4 4 5% 5% 5% 44%	1752
	21st to end	Night	9% 6% 3 6% 6% 4 5% 5% 6% 8% 42%	1620
May	1st to 10th	Night	6% 5% 2 5% 5% 3 6% 5% 6% 6% 50%	1482
	11th to 20th	Night	9% 6% 2 4 6% 4 5% 6% 7% 8% 43%	1416
	21st to end	Night	7% 5% 3 5% 6% 4 7% 5% 7% 7% 45%	1552
June	1st to 10th	Night	9% 6% 4 5% 6% 3 4 5% 5% 7% 48%	1440
	11th to 20th	Night	10% 5% 2 4 6% 3 4 4 5% 6% 50%	1440
	21st to end	Night	6% 4 2 3 5% 3 5% 4 5% 7% 57%	1440
July	1st to 10th	Night	2 2 1 2 3 2 2 5% 4 7% 70%	1440
	11th to 20th	Night	3 1 1 2 3 1 3 3 5% 6% 74%	1440
	21st to end	Night	2 1 1 2 2 1 2 3 2 5% 80%	1576
August	1st to 10th	Night	4 1 1 2 2 1 2 4 5% 6% 72%	1432
	11th to 20th	Night	2 2 1 3 3 1 3 3 4 6% 73%	1518
	21st to end	Night	3 2 1 2 3 2 4 3 5% 5% 70%	1976
September	1st to 10th	Night	3 2 1 2 3 2 3 4 4 6% 71%	1800
	11th to 20th	Night	5% 3 1 4 4 3 5% 4 5% 7% 58%	1882
	21st to end	Night	8% 4 2 4 3 3 4 4 5% 9% 53%	1980
October	1st to 10th	Night	10% 5% 2 4 4 3 4 5% 5% 7% 52%	2071
	11th to 20th	Night	10% 6% 2 5% 5% 3 4 4 5% 7% 50%	2236
	21st to end	Night	12% 7% 3 5% 5% 3 4 5% 5% 7% 45%	2574
November	1st to 10th	Night	16% 9% 3 7% 6% 3 5% 5% 6% 6% 34%	2405
	11th to 20th	Night	16% 8% 4 8% 6% 3 6% 5% 5% 6% 33%	2565
	21st to end	Night	15% 8% 4 6% 6% 4 5% 6% 6% 6% 33%	2660
December	1st to 10th	Night	14% 10% 5% 8% 7% 4 5% 5% 5% 6% 30%	2802
	11th to 20th	Night	18% 15% 7% 12% 10% 4 4 5% 6% 6% 14%	3482
	21st to end	Night	17% 12% 6% 12% 8% 4 4 4 5% 6% 22%	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	65% 10% 13% 10% 1	2539
	11th to 20th	Day	65% 10% 12% 11% 3 1	2540
	21st to end	Day	71% 6% 13% 8% 1	2794
February	1st to 10th	Day	57% 9% 16% 12% 5%	1567
	11th to 20th	Day	55% 8% 13% 17% 6%	1778
	21st to end	Day	53% 8% 11% 19% 8% 1	1570
March	1st to 10th	Day	51% 7% 15% 20% 7% 1	1871
	11th to 20th	Day	51% 7% 14% 22% 6%	1832
	21st to end	Day	52% 9% 17% 16% 5%	2376
April	1st to 10th	Day	47% 8% 15% 19% 9% 1	2160
	11th to 20th	Day	41% 6% 15% 22% 14% 2	2158
	21st to end	Day	38% 7% 13% 25% 15% 2	2340
May	1st to 10th	Day	30% 5% 12% 31% 19% 2	2474
	11th to 20th	Day	38% 8% 14% 26% 14% 1	2480
	21st to end	Day	38% 7% 14% 27% 12% 2	2724
June	1st to 10th	Day	40% 6% 9% 24% 19% 3	2520
	11th to 20th	Day	32% 5% 14% 27% 18% 4	2520
	21st to end	Day	21% 5% 9% 30% 28% 8%	2520
July	1st to 10th	Day	15% 3 7% 24% 32% 20%	2451
	11th to 20th	Day	13% 4 7% 16% 38% 22%	2445
	21st to end	Day	9% 2 4 16% 44% 25%	2589
August	1st to 10th	Day	14% 3 7% 21% 35% 20%	2490
	11th to 20th	Day	13% 4 7% 25% 36% 15%	2380
	21st to end	Day	20% 5% 9% 27% 31% 10%	2376
September	1st to 10th	Day	15% 4 9% 31% 28% 14%	2160
	11th to 20th	Day	26% 5% 13% 24% 24% 8%	2077
	21st to end	Day	29% 6% 17% 28% 16% 4	1980
October	1st to 10th	Day	33% 5% 13% 30% 16% 2	1886
	11th to 20th	Day	33% 6% 16% 33% 11% 1	1724
	21st to end	Day	41% 9% 15% 24% 11%	1782
November	1st to 10th	Day	46% 9% 16% 22% 6% 1	1674
	11th to 20th	Day	57% 8% 15% 16% 3 1	1615
	21st to end	Day	56% 12% 15% 12% 4 1	1520
December	1st to 10th	Day	62% 9% 13% 12% 4	1353
	11th to 20th	Day	73% 10% 7% 8% 1	1725
	21st to end	Day	63% 8% 14% 11% 3	2794
January	1st to 10th	Night	67% 7% 12% 12% 1 1	4406
	11th to 20th	Night	59% 7% 17% 12% 3	4420
	21st to end	Night	63% 9% 15% 11% 2	4862
February	1st to 10th	Night	56% 7% 15% 15% 6% 1	2612
	11th to 20th	Night	49% 8% 17% 18% 8%	2299
	21st to end	Night	50% 8% 14% 19% 8% 1	1884
March	1st to 10th	Night	47% 7% 12% 22% 11% 1	2249
	11th to 20th	Night	46% 7% 11% 24% 12% 1	2123
	21st to end	Night	50% 8% 15% 19% 7%	1980
April	1st to 10th	Night	44% 7% 11% 23% 12% 1	1800
	11th to 20th	Night	41% 7% 9% 23% 16% 3	1752
	21st to end	Night	39% 7% 12% 20% 17% 5%	1620
May	1st to 10th	Night	31% 6% 10% 29% 20% 4	1482
	11th to 20th	Night	36% 8% 10% 25% 18% 3	1416
	21st to end	Night	36% 7% 11% 31% 13% 2	1552
June	1st to 10th	Night	37% 5% 9% 23% 23% 4	1440
	11th to 20th	Night	34% 6% 7% 28% 21% 5%	1440
	21st to end	Night	26% 4 9% 24% 26% 11%	1440
July	1st to 10th	Night	15% 3 7% 19% 32% 25%	1400
	11th to 20th	Night	13% 3 7% 15% 30% 32%	1392
	21st to end	Night	10% 2 3 12% 35% 37%	1488
August	1st to 10th	Night	13% 3 7% 14% 36% 27%	1424
	11th to 20th	Night	14% 4 6% 19% 33% 24%	1518
	21st to end	Night	17% 3 7% 22% 34% 16%	1976
September	1st to 10th	Night	16% 4 7% 25% 31% 19%	1800
	11th to 20th	Night	25% 5% 9% 23% 26% 12%	1882
	21st to end	Night	27% 5% 11% 29% 20% 8%	1980
October	1st to 10th	Night	32% 6% 10% 27% 24% 1	2071
	11th to 20th	Night	35% 6% 12% 25% 19% 3	2236
	21st to end	Night	39% 6% 12% 26% 15% 2	2574
November	1st to 10th	Night	49% 7% 13% 23% 6% 1	2405
	11th to 20th	Night	53% 7% 16% 17% 6% 1	2565
	21st to end	Night	50% 9% 17% 18% 6%	2660
December	1st to 10th	Night	55% 10% 15% 17% 4	2802
	11th to 20th	Night	68% 11% 11% 7% 2	3479
	21st to end	Night	63% 7% 12% 13% 5%	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	28% 6% 29% 19% 12% 6%	180
	11th to 20th	Day	30% 6% 17% 27% 16% 4	180
	21st to end	Day	29% 6% 23% 25% 15% 3	198
February	1st to 10th	Day	23% 7% 30% 25% 12% 3	227
	11th to 20th	Day	24% 12% 24% 23% 14% 3	415
	21st to end	Day	19% 11% 27% 26% 15% 3	382
March	1st to 10th	Day	18% 12% 31% 19% 16% 4	449
	11th to 20th	Day	13% 10% 23% 26% 21% 6%	420
	21st to end	Day	15% 14% 28% 26% 14% 3	462
April	1st to 10th	Day	16% 13% 25% 26% 15% 5%	420
	11th to 20th	Day	13% 14% 32% 21% 15% 4	412
	21st to end	Day	12% 10% 28% 25% 19% 6%	420
May	1st to 10th	Day	7% 10% 22% 33% 22% 6%	423
	11th to 20th	Day	17% 4 21% 25% 18% 16%	448
	21st to end	Day	9% 6% 21% 27% 23% 14%	485
June	1st to 10th	Day	12% 6% 22% 24% 23% 13%	450
	11th to 20th	Day	10% 10% 29% 29% 14% 9%	450
	21st to end	Day	5% 5% 20% 29% 29% 13%	450
July	1st to 10th	Day	3 2 19% 31% 39% 6%	446
	11th to 20th	Day	1 4 19% 35% 30% 11%	444
	21st to end	Day	1 2 17% 30% 32% 18%	487
August	1st to 10th	Day	3 4 14% 30% 32% 18%	447
	11th to 20th	Day	3 1 13% 28% 35% 21%	437
	21st to end	Day	5% 5% 20% 26% 26% 18%	495
September	1st to 10th	Day	5% 3 20% 29% 28% 15%	450
	11th to 20th	Day	8% 6% 20% 23% 29% 15%	450
	21st to end	Day	6% 9% 23% 23% 30% 8%	450
October	1st to 10th	Day	11% 8% 20% 27% 24% 10%	450
	11th to 20th	Day	13% 9% 16% 27% 23% 12%	374
	21st to end	Day	17% 9% 23% 30% 13% 8%	297
November	1st to 10th	Day	20% 10% 23% 31% 13% 3	270
	11th to 20th	Day	22% 12% 18% 25% 14% 9%	225
	21st to end	Day	18% 7% 24% 26% 21% 5%	180
December	1st to 10th	Day	22% 7% 22% 24% 16% 9%	180
	11th to 20th	Day	26% 11% 23% 22% 16% 3	180
	21st to end	Day	27% 5% 26% 26% 13% 3	198
January	1st to 10th	Night	29% 8% 22% 26% 13% 2	760
	11th to 20th	Night	24% 6% 18% 31% 17% 4	760
	21st to end	Night	21% 4 18% 34% 21% 2	836
February	1st to 10th	Night	24% 6% 23% 32% 13% 1	760
	11th to 20th	Night	19% 8% 22% 33% 17% 1	744
	21st to end	Night	17% 10% 22% 34% 16% 1	628
March	1st to 10th	Night	17% 5% 25% 33% 16% 3	750
	11th to 20th	Night	16% 8% 22% 31% 20% 2	720
	21st to end	Night	17% 6% 29% 35% 12% 2	792
April	1st to 10th	Night	15% 6% 24% 36% 18% 2	720
	11th to 20th	Night	13% 7% 31% 32% 15% 2	684
	21st to end	Night	11% 6% 27% 34% 20% 1	540
May	1st to 10th	Night	9% 7% 25% 33% 24% 2	402
	11th to 20th	Night	11% 5% 16% 34% 29% 5%	354
	21st to end	Night	7% 5% 21% 36% 28% 3	389
June	1st to 10th	Night	11% 4 23% 39% 21% 3	360
	11th to 20th	Night	14% 6% 28% 34% 17% 2	360
	21st to end	Night	7% 3 17% 42% 28% 3	360
July	1st to 10th	Night	5% 2 15% 45% 32% 2	350
	11th to 20th	Night	3 3 17% 46% 30% 1	348
	21st to end	Night	1 2 13% 46% 35% 3	394
August	1st to 10th	Night	4 1 13% 38% 38% 5%	358
	11th to 20th	Night	3 2 10% 37% 40% 8%	450
	21st to end	Night	4 2 17% 39% 33% 5%	788
September	1st to 10th	Night	4 2 15% 45% 28% 6%	720
	11th to 20th	Night	6% 3 17% 34% 33% 8%	720
	21st to end	Night	10% 4 19% 33% 29% 5%	720
October	1st to 10th	Night	14% 3 18% 37% 26% 3	720
	11th to 20th	Night	13% 7% 18% 33% 26% 3	720
	21st to end	Night	16% 5% 23% 34% 17% 5%	792
November	1st to 10th	Night	21% 5% 21% 37% 15% 1	740
	11th to 20th	Night	20% 8% 21% 33% 15% 2	760
	21st to end	Night	21% 5% 19% 34% 19% 3	760
December	1st to 10th	Night	18% 6% 19% 37% 17% 3	902
	11th to 20th	Night	25% 6% 20% 34% 13% 1	935
	21st to end	Night	30% 7% 20% 31% 11% 1	836

Page generated at 2024-03-05 04:24:03. Version ac07

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