Delta Rocky Crest Resort
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Delta Rocky Crest Resort clear sky chart from 2005-11-06 to 2024-11-05.

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	17% 11% 4 8% 5% 4 4 3 5% 6% 33%	101808
	Night	17% 13% 4 9% 5% 4 4 3 5% 6% 31%	97233
Transparency	Day	51% 6% 11% 21% 10% 1	105387
	Night	54% 6% 11% 19% 10% 1	101743
Seeing	Day	23% 14% 31% 20% 8% 3	15012
	Night	24% 12% 28% 25% 10% 1	23998

By Month

Percentage Cloud Cover NE (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% 23% 13% 11% 3 4 2 2 3 3 19%	2208
	11th to 20th	Day	11% 19% 8% 21% 8% 5% 4 3 4 4 14%	2610
	21st to end	Day	17% 23% 9% 12% 5% 5% 4 2 3 3 17%	3124
February	1st to 10th	Day	13% 21% 7% 15% 7% 3 4 3 4 4 20%	1710
	11th to 20th	Day	13% 17% 7% 12% 6% 5% 3 3 4 5% 26%	1663
	21st to end	Day	15% 18% 6% 13% 6% 5% 4 3 4 4 23%	1444
March	1st to 10th	Day	19% 15% 4 8% 5% 4 4 3 4 5% 29%	3418
	11th to 20th	Day	11% 17% 7% 10% 6% 4 4 2 5% 6% 27%	3480
	21st to end	Day	14% 13% 6% 7% 4 4 4 4 4 5% 36%	3815
April	1st to 10th	Day	21% 14% 4 6% 4 4 4 3 5% 6% 29%	2242
	11th to 20th	Day	22% 11% 3 5% 4 4 4 2 4 5% 36%	2378
	21st to end	Day	23% 11% 3 6% 4 3 4 3 4 5% 34%	2470
May	1st to 10th	Day	20% 8% 3 7% 5% 4 4 4 5% 7% 33%	4158
	11th to 20th	Day	14% 8% 3 6% 4 4 4 3 5% 8% 40%	4398
	21st to end	Day	19% 5% 2 5% 4 4 4 3 5% 6% 43%	4837
June	1st to 10th	Day	19% 7% 2 6% 6% 4 4 3 6% 7% 36%	2708
	11th to 20th	Day	14% 6% 2 6% 6% 4 4 4 6% 8% 39%	2850
	21st to end	Day	20% 7% 2 6% 5% 4 4 3 6% 8% 35%	2850
July	1st to 10th	Day	16% 6% 2 7% 5% 4 6% 4 6% 8% 36%	4760
	11th to 20th	Day	15% 6% 2 6% 4 4 4 3 6% 8% 44%	4601
	21st to end	Day	11% 5% 2 5% 4 4 4 4 6% 7% 49%	4605
August	1st to 10th	Day	13% 7% 3 7% 5% 5% 6% 4 6% 9% 37%	4104
	11th to 20th	Day	17% 6% 2 6% 4 4 4 4 6% 9% 37%	4044
	21st to end	Day	10% 4 2 5% 4 4 5% 5% 6% 8% 45%	4414
September	1st to 10th	Day	14% 6% 2 7% 3 4 5% 4 6% 7% 42%	2280
	11th to 20th	Day	16% 6% 2 5% 3 4 4 3 6% 6% 45%	2159
	21st to end	Day	21% 8% 3 6% 5% 5% 4 3 5% 6% 36%	2059
October	1st to 10th	Day	22% 8% 3 7% 4 4 4 3 4 7% 34%	1900
	11th to 20th	Day	27% 11% 3 7% 4 5% 4 4 5% 7% 23%	1900
	21st to end	Day	30% 14% 3 8% 4 3 4 3 4 5% 21%	2076
November	1st to 10th	Day	20% 14% 4 7% 4 4 4 4 5% 7% 26%	1567
	11th to 20th	Day	20% 16% 4 8% 5% 5% 5% 4 5% 5% 22%	1520
	21st to end	Day	23% 21% 4 7% 6% 5% 4 3 4 5% 17%	1520
December	1st to 10th	Day	18% 27% 5% 9% 5% 4 4 3 3 4 18%	1520
	11th to 20th	Day	19% 25% 5% 11% 4 3 2 2 3 4 21%	1906
	21st to end	Day	27% 21% 5% 11% 5% 4 3 2 3 4 14%	2510
January	1st to 10th	Night	17% 21% 12% 14% 6% 4 3 2 3 3 14%	4748
	11th to 20th	Night	14% 17% 5% 20% 7% 5% 6% 4 4 4 13%	4330
	21st to end	Night	17% 19% 9% 13% 6% 4 4 3 4 4 17%	4532
February	1st to 10th	Night	13% 19% 6% 12% 7% 5% 4 4 5% 5% 19%	2470
	11th to 20th	Night	13% 16% 7% 12% 6% 5% 4 3 4 5% 25%	2403
	21st to end	Night	15% 18% 5% 10% 6% 4 4 4 4 4 23%	2008
March	1st to 10th	Night	16% 13% 4 9% 5% 4 4 3 5% 6% 31%	3420
	11th to 20th	Night	12% 16% 7% 9% 5% 4 4 3 4 5% 31%	3479
	21st to end	Night	15% 10% 4 7% 5% 4 4 3 5% 6% 36%	3817
April	1st to 10th	Night	22% 13% 3 7% 5% 3 4 3 4 6% 30%	1938
	11th to 20th	Night	19% 11% 3 8% 4 3 4 3 4 5% 36%	1767
	21st to end	Night	21% 10% 3 8% 5% 5% 4 3 5% 6% 31%	1710
May	1st to 10th	Night	17% 6% 2 7% 4 5% 4 4 6% 7% 37%	2781
	11th to 20th	Night	14% 8% 2 6% 5% 4 3 4 6% 7% 40%	2495
	21st to end	Night	12% 7% 2 6% 4 4 4 4 5% 8% 44%	2738
June	1st to 10th	Night	15% 8% 2 7% 4 5% 5% 3 6% 8% 37%	1466
	11th to 20th	Night	13% 6% 2 5% 4 3 5% 3 8% 9% 44%	1330
	21st to end	Night	16% 7% 2 5% 5% 4 3 4 6% 8% 40%	1330
July	1st to 10th	Night	11% 7% 3 7% 4 4 4 3 5% 7% 45%	2210
	11th to 20th	Night	16% 5% 2 4 3 3 4 3 5% 7% 48%	2360
	21st to end	Night	9% 6% 2 5% 4 3 4 3 5% 7% 51%	2945
August	1st to 10th	Night	11% 6% 2 7% 4 4 4 3 5% 8% 45%	2825
	11th to 20th	Night	16% 6% 2 6% 4 4 4 3 4 6% 45%	2785
	21st to end	Night	15% 5% 2 4 3 3 4 3 5% 7% 50%	3209
September	1st to 10th	Night	12% 5% 2 6% 4 5% 4 3 6% 7% 47%	1900
	11th to 20th	Night	13% 5% 2 4 4 3 4 3 5% 8% 49%	2019
	21st to end	Night	19% 7% 2 6% 5% 4 4 3 4 6% 41%	2120
October	1st to 10th	Night	21% 8% 2 6% 4 4 5% 3 5% 6% 36%	2280
	11th to 20th	Night	25% 11% 3 8% 5% 4 4 4 4 6% 26%	2280
	21st to end	Night	27% 12% 4 8% 5% 3 3 3 4 5% 25%	2518
November	1st to 10th	Night	23% 13% 3 7% 4 3 4 2 4 6% 30%	2608
	11th to 20th	Night	18% 17% 5% 8% 5% 5% 4 3 6% 5% 24%	2660
	21st to end	Night	25% 19% 6% 9% 4 4 4 3 4 5% 17%	2660
December	1st to 10th	Night	19% 26% 7% 9% 5% 4 3 3 5% 5% 13%	2660
	11th to 20th	Night	21% 23% 7% 12% 5% 3 3 2 3 4 17%	3288
	21st to end	Night	25% 23% 6% 13% 4 4 3 3 3 4 12%	5144

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	72% 4 9% 9% 5%	2209
	11th to 20th	Day	76% 4 7% 7% 5% 1	2610
	21st to end	Day	73% 5% 6% 9% 6% 1	3124
February	1st to 10th	Day	70% 4 7% 14% 4 1	1710
	11th to 20th	Day	61% 6% 9% 14% 9% 1	1672
	21st to end	Day	65% 5% 8% 16% 7%	1444
March	1st to 10th	Day	59% 5% 13% 11% 11%	3421
	11th to 20th	Day	59% 6% 11% 17% 8% 1	3480
	21st to end	Day	47% 7% 10% 20% 14% 2	3815
April	1st to 10th	Day	57% 5% 10% 18% 9% 1	2242
	11th to 20th	Day	51% 5% 7% 23% 13% 1	2378
	21st to end	Day	52% 5% 9% 18% 13% 3	2470
May	1st to 10th	Day	48% 8% 9% 22% 11% 2	4170
	11th to 20th	Day	41% 8% 13% 27% 10% 1	4402
	21st to end	Day	41% 6% 13% 20% 16% 4	4837
June	1st to 10th	Day	47% 7% 9% 23% 13% 1	2708
	11th to 20th	Day	42% 6% 11% 24% 16% 1	2850
	21st to end	Day	47% 6% 13% 21% 11% 1	2850
July	1st to 10th	Day	44% 7% 15% 23% 10% 1	4686
	11th to 20th	Day	38% 5% 15% 31% 10%	4520
	21st to end	Day	34% 6% 10% 31% 18%	4458
August	1st to 10th	Day	44% 6% 14% 25% 10% 1	4091
	11th to 20th	Day	42% 7% 15% 26% 8%	4083
	21st to end	Day	34% 7% 13% 35% 10%	4414
September	1st to 10th	Day	40% 7% 14% 27% 12% 1	2280
	11th to 20th	Day	39% 6% 15% 28% 12% 1	2159
	21st to end	Day	50% 7% 11% 23% 9%	2059
October	1st to 10th	Day	46% 5% 13% 24% 11% 1	3160
	11th to 20th	Day	50% 7% 14% 24% 6%	3140
	21st to end	Day	59% 5% 14% 17% 5%	3402
November	1st to 10th	Day	56% 7% 14% 18% 5%	1567
	11th to 20th	Day	64% 5% 13% 12% 5% 1	1520
	21st to end	Day	69% 7% 9% 11% 3 1	1520
December	1st to 10th	Day	72% 4 9% 10% 4 1	1520
	11th to 20th	Day	71% 4 7% 11% 7%	1906
	21st to end	Day	76% 4 6% 10% 3	2510
January	1st to 10th	Night	76% 5% 7% 7% 4	4748
	11th to 20th	Night	73% 9% 6% 7% 4 1	4330
	21st to end	Night	70% 7% 7% 10% 5% 1	4532
February	1st to 10th	Night	66% 6% 9% 14% 5% 1	2470
	11th to 20th	Night	61% 5% 10% 16% 7% 1	2405
	21st to end	Night	64% 5% 9% 15% 7% 1	2008
March	1st to 10th	Night	53% 6% 13% 16% 11% 1	3430
	11th to 20th	Night	54% 7% 14% 16% 8% 2	3480
	21st to end	Night	47% 6% 10% 22% 13% 2	3817
April	1st to 10th	Night	55% 5% 8% 19% 11% 2	1938
	11th to 20th	Night	50% 5% 7% 21% 15% 2	1767
	21st to end	Night	53% 5% 9% 15% 16% 2	1710
May	1st to 10th	Night	43% 7% 12% 25% 11% 2	2788
	11th to 20th	Night	40% 7% 12% 26% 15% 1	2496
	21st to end	Night	37% 7% 12% 24% 18% 2	2739
June	1st to 10th	Night	45% 6% 10% 23% 14% 2	1466
	11th to 20th	Night	35% 6% 13% 26% 20%	1330
	21st to end	Night	42% 7% 15% 24% 12% 1	1330
July	1st to 10th	Night	38% 5% 14% 25% 16% 2	2175
	11th to 20th	Night	36% 6% 12% 35% 11% 1	2318
	21st to end	Night	33% 5% 11% 31% 20% 1	2851
August	1st to 10th	Night	37% 4 17% 24% 16% 1	2814
	11th to 20th	Night	39% 6% 18% 25% 11% 1	2812
	21st to end	Night	34% 5% 11% 37% 13% 1	3209
September	1st to 10th	Night	36% 8% 16% 26% 14% 1	1900
	11th to 20th	Night	33% 6% 16% 31% 13%	2019
	21st to end	Night	44% 5% 12% 28% 10%	2120
October	1st to 10th	Night	38% 5% 11% 28% 17%	3800
	11th to 20th	Night	49% 6% 15% 23% 7%	3779
	21st to end	Night	57% 5% 15% 16% 6%	4142
November	1st to 10th	Night	55% 5% 13% 21% 6%	2608
	11th to 20th	Night	59% 5% 14% 14% 6% 1	2660
	21st to end	Night	68% 5% 12% 11% 3	2660
December	1st to 10th	Night	73% 6% 8% 9% 4	2660
	11th to 20th	Night	72% 5% 8% 11% 4	3288
	21st to end	Night	78% 4 7% 9% 3	5144

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	22% 23% 34% 14% 4 1	180
	11th to 20th	Day	27% 21% 31% 15% 5%	222
	21st to end	Day	30% 13% 35% 17% 5%	297
February	1st to 10th	Day	30% 26% 33% 8% 2 1	270
	11th to 20th	Day	23% 25% 40% 11% 1	270
	21st to end	Day	35% 28% 30% 7%	225
March	1st to 10th	Day	23% 21% 37% 15% 4	446
	11th to 20th	Day	22% 20% 37% 15% 5% 1	460
	21st to end	Day	29% 17% 32% 16% 6% 1	506
April	1st to 10th	Day	29% 18% 31% 14% 8%	460
	11th to 20th	Day	36% 17% 22% 16% 8% 2	452
	21st to end	Day	30% 14% 35% 13% 7% 1	460
May	1st to 10th	Day	25% 13% 33% 18% 8% 3	463
	11th to 20th	Day	20% 16% 28% 23% 10% 3	487
	21st to end	Day	19% 13% 33% 22% 11% 2	529
June	1st to 10th	Day	20% 13% 32% 26% 7% 1	538
	11th to 20th	Day	16% 14% 33% 26% 9% 2	680
	21st to end	Day	23% 10% 35% 22% 7% 2	680
July	1st to 10th	Day	13% 9% 34% 29% 14% 2	671
	11th to 20th	Day	16% 11% 28% 29% 13% 4	574
	21st to end	Day	13% 8% 34% 30% 10% 6%	532
August	1st to 10th	Day	16% 5% 27% 31% 14% 7%	486
	11th to 20th	Day	18% 4 27% 26% 15% 10%	479
	21st to end	Day	15% 8% 30% 27% 14% 6%	539
September	1st to 10th	Day	16% 11% 29% 25% 12% 7%	490
	11th to 20th	Day	16% 6% 27% 25% 18% 8%	490
	21st to end	Day	20% 12% 23% 29% 13% 3	490
October	1st to 10th	Day	24% 16% 26% 19% 12% 3	490
	11th to 20th	Day	29% 18% 33% 14% 5% 1	490
	21st to end	Day	38% 16% 30% 14% 2	525
November	1st to 10th	Day	29% 19% 36% 15% 1	213
	11th to 20th	Day	24% 24% 37% 12% 2	180
	21st to end	Day	34% 18% 38% 8% 2 1	180
December	1st to 10th	Day	32% 20% 31% 15% 2 1	180
	11th to 20th	Day	38% 24% 23% 12% 2 1	180
	21st to end	Day	39% 19% 31% 7% 4 1	198
January	1st to 10th	Night	28% 17% 31% 20% 4 1	950
	11th to 20th	Night	31% 15% 31% 18% 4 1	779
	21st to end	Night	21% 12% 36% 23% 8% 1	836
February	1st to 10th	Night	25% 17% 34% 20% 3	760
	11th to 20th	Night	21% 16% 35% 22% 6%	743
	21st to end	Night	24% 21% 29% 21% 4	628
March	1st to 10th	Night	21% 19% 33% 23% 4	760
	11th to 20th	Night	20% 18% 34% 23% 5% 1	760
	21st to end	Night	21% 12% 32% 26% 9% 1	836
April	1st to 10th	Night	28% 14% 30% 23% 5%	760
	11th to 20th	Night	25% 14% 27% 24% 9% 1	643
	21st to end	Night	25% 10% 29% 26% 9%	570
May	1st to 10th	Night	23% 6% 25% 34% 10% 1	544
	11th to 20th	Night	17% 8% 29% 34% 10% 1	374
	21st to end	Night	13% 6% 31% 34% 16%	411
June	1st to 10th	Night	20% 7% 27% 34% 12%	380
	11th to 20th	Night	16% 7% 26% 37% 13%	380
	21st to end	Night	21% 6% 23% 36% 14% 1	380
July	1st to 10th	Night	11% 5% 21% 45% 18% 1	370
	11th to 20th	Night	14% 7% 23% 35% 21% 1	368
	21st to end	Night	11% 5% 23% 37% 23% 1	534
August	1st to 10th	Night	15% 5% 17% 35% 26% 2	567
	11th to 20th	Night	13% 4 18% 37% 25% 3	564
	21st to end	Night	19% 5% 23% 30% 20% 2	673
September	1st to 10th	Night	14% 6% 27% 30% 19% 3	760
	11th to 20th	Night	14% 7% 23% 31% 22% 4	760
	21st to end	Night	22% 6% 21% 31% 17% 3	760
October	1st to 10th	Night	23% 11% 27% 26% 12% 1	760
	11th to 20th	Night	31% 12% 25% 23% 8% 1	760
	21st to end	Night	34% 14% 29% 19% 4	836
November	1st to 10th	Night	34% 9% 26% 22% 7% 1	760
	11th to 20th	Night	29% 16% 30% 19% 6%	760
	21st to end	Night	35% 14% 29% 18% 4	760
December	1st to 10th	Night	34% 19% 28% 14% 4	760
	11th to 20th	Night	31% 19% 33% 14% 3 1	760
	21st to end	Night	34% 15% 30% 18% 3	992

Page generated at 2024-11-03 02:11:15. Version ac07

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