Tatlock Quarry Outlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tatlock Quarry Outlook 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	16% 10% 3 8% 5% 5% 4 4 5% 7% 33%	101813
	Night	16% 11% 4 9% 5% 5% 4 3 5% 6% 32%	97815
Transparency	Day	50% 6% 12% 21% 10% 1	105322
	Night	51% 6% 12% 20% 10% 1	102395
Seeing	Day	23% 16% 31% 19% 8% 3	14520
	Night	22% 14% 31% 24% 9% 1	23688

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	13% 16% 5% 13% 7% 4 5% 3 5% 6% 23%	2517
	11th to 20th	Day	12% 16% 7% 13% 8% 6% 5% 3 4 3 23%	2520
	21st to end	Day	15% 21% 7% 14% 7% 6% 4 3 3 3 17%	2967
February	1st to 10th	Day	14% 15% 4 14% 6% 5% 4 3 5% 5% 23%	1710
	11th to 20th	Day	11% 15% 5% 11% 6% 6% 4 4 5% 5% 28%	1663
	21st to end	Day	18% 14% 3 9% 7% 6% 4 4 5% 5% 25%	1546
March	1st to 10th	Day	19% 16% 5% 10% 5% 4 4 3 4 5% 27%	3180
	11th to 20th	Day	10% 16% 5% 10% 7% 6% 5% 3 5% 5% 29%	3480
	21st to end	Day	11% 10% 3 8% 5% 4 3 3 5% 5% 43%	3974
April	1st to 10th	Day	21% 13% 3 8% 4 4 4 3 4 6% 31%	2280
	11th to 20th	Day	21% 11% 3 7% 3 3 4 3 4 4 37%	2254
	21st to end	Day	21% 11% 3 7% 5% 4 4 3 4 5% 32%	2406
May	1st to 10th	Day	20% 9% 3 7% 5% 4 5% 4 5% 6% 32%	4426
	11th to 20th	Day	16% 9% 4 9% 5% 4 4 4 5% 8% 33%	4398
	21st to end	Day	14% 6% 2 7% 5% 5% 5% 4 6% 7% 39%	4837
June	1st to 10th	Day	20% 9% 3 8% 6% 5% 5% 4 6% 6% 30%	2660
	11th to 20th	Day	14% 6% 2 7% 5% 5% 5% 5% 6% 7% 38%	2660
	21st to end	Day	18% 7% 3 7% 6% 5% 5% 4 6% 7% 32%	2660
July	1st to 10th	Day	11% 6% 3 8% 6% 5% 5% 5% 7% 9% 35%	4440
	11th to 20th	Day	12% 5% 2 6% 5% 5% 5% 4 7% 9% 40%	4440
	21st to end	Day	10% 5% 2 5% 5% 5% 5% 4 6% 8% 43%	4814
August	1st to 10th	Day	15% 8% 3 8% 5% 4 5% 4 6% 7% 36%	4267
	11th to 20th	Day	17% 6% 2 6% 5% 4 5% 4 6% 9% 36%	4044
	21st to end	Day	12% 6% 2 6% 4 4 5% 5% 6% 10% 39%	4180
September	1st to 10th	Day	14% 5% 3 6% 5% 5% 5% 4 5% 8% 40%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 6% 8% 47%	2280
	21st to end	Day	17% 7% 2 6% 5% 5% 5% 2 5% 7% 39%	2015
October	1st to 10th	Day	20% 8% 3 7% 5% 5% 4 3 4 6% 35%	1900
	11th to 20th	Day	20% 10% 3 9% 5% 4 5% 3 5% 6% 29%	1900
	21st to end	Day	25% 11% 3 8% 5% 4 5% 3 5% 6% 26%	1973
November	1st to 10th	Day	14% 10% 3 8% 6% 4 5% 4 6% 6% 34%	1736
	11th to 20th	Day	17% 13% 3 10% 5% 6% 4 3 4 6% 29%	1600
	21st to end	Day	20% 15% 5% 10% 7% 6% 4 3 5% 6% 20%	1600
December	1st to 10th	Day	19% 20% 7% 10% 7% 5% 3 3 4 5% 16%	1528
	11th to 20th	Day	18% 15% 6% 9% 6% 4 4 3 4 6% 25%	1906
	21st to end	Day	27% 18% 5% 13% 5% 3 2 2 3 3 19%	2772
January	1st to 10th	Night	16% 14% 7% 12% 7% 5% 4 4 6% 6% 19%	4429
	11th to 20th	Night	12% 14% 5% 14% 9% 6% 5% 4 5% 5% 22%	4440
	21st to end	Night	16% 19% 7% 12% 6% 7% 3 3 4 4 20%	4688
February	1st to 10th	Night	12% 16% 6% 11% 7% 5% 4 4 5% 5% 23%	2470
	11th to 20th	Night	12% 12% 5% 11% 7% 5% 4 3 4 6% 30%	2403
	21st to end	Night	14% 12% 4 9% 7% 5% 5% 4 6% 6% 29%	1907
March	1st to 10th	Night	19% 13% 4 10% 6% 4 4 3 3 4 31%	3642
	11th to 20th	Night	13% 16% 5% 10% 5% 5% 4 4 5% 6% 26%	3479
	21st to end	Night	14% 9% 3 8% 5% 4 4 3 5% 6% 39%	3658
April	1st to 10th	Night	19% 11% 3 8% 4 4 3 2 4 7% 34%	1900
	11th to 20th	Night	19% 9% 3 7% 5% 4 4 3 4 5% 37%	1875
	21st to end	Night	20% 11% 3 7% 5% 4 5% 3 4 6% 32%	1789
May	1st to 10th	Night	21% 10% 3 7% 4 4 5% 3 5% 5% 33%	2514
	11th to 20th	Night	17% 8% 3 6% 4 4 5% 3 6% 7% 36%	2495
	21st to end	Night	13% 7% 2 7% 4 4 5% 4 6% 8% 41%	2738
June	1st to 10th	Night	15% 7% 2 6% 5% 6% 5% 5% 6% 7% 35%	1520
	11th to 20th	Night	12% 7% 2 8% 4 5% 4 4 5% 7% 43%	1520
	21st to end	Night	16% 8% 3 7% 4 5% 5% 4 6% 7% 36%	1520
July	1st to 10th	Night	9% 7% 3 9% 6% 5% 6% 5% 6% 7% 37%	2520
	11th to 20th	Night	12% 5% 2 6% 5% 5% 4 4 5% 8% 44%	2520
	21st to end	Night	9% 5% 2 7% 5% 5% 5% 4 6% 7% 45%	2739
August	1st to 10th	Night	10% 6% 2 7% 5% 4 5% 4 7% 8% 42%	2658
	11th to 20th	Night	13% 6% 2 6% 4 5% 4 3 5% 7% 44%	2785
	21st to end	Night	11% 5% 2 6% 5% 5% 5% 3 6% 7% 44%	3444
September	1st to 10th	Night	11% 7% 2 6% 4 4 4 3 6% 6% 47%	1900
	11th to 20th	Night	13% 5% 2 4 3 4 4 3 5% 6% 50%	1900
	21st to end	Night	16% 7% 3 6% 4 4 3 3 5% 6% 43%	2163
October	1st to 10th	Night	18% 9% 2 6% 5% 4 4 3 5% 6% 39%	2280
	11th to 20th	Night	19% 9% 3 9% 5% 4 4 3 6% 8% 31%	2280
	21st to end	Night	21% 11% 4 8% 5% 4 4 3 5% 7% 28%	2623
November	1st to 10th	Night	16% 11% 3 8% 4 4 5% 3 4 5% 36%	2558
	11th to 20th	Night	16% 12% 4 8% 6% 4 5% 4 5% 6% 30%	2800
	21st to end	Night	19% 15% 5% 10% 6% 3 4 4 5% 6% 24%	2800
December	1st to 10th	Night	19% 18% 5% 11% 6% 5% 4 4 5% 5% 18%	2686
	11th to 20th	Night	20% 15% 5% 10% 5% 4 3 3 3 4 26%	3288
	21st to end	Night	28% 17% 5% 13% 5% 4 3 3 4 3 16%	4884

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	62% 6% 15% 10% 7% 1	2518
	11th to 20th	Day	65% 5% 10% 12% 7% 1	2520
	21st to end	Day	73% 4 7% 10% 5% 1	2967
February	1st to 10th	Day	62% 5% 9% 18% 5% 1	1710
	11th to 20th	Day	57% 4 11% 17% 9% 1	1672
	21st to end	Day	61% 4 11% 12% 11% 1	1546
March	1st to 10th	Day	60% 5% 9% 16% 9% 1	3183
	11th to 20th	Day	55% 6% 12% 15% 10% 2	3480
	21st to end	Day	42% 4 8% 23% 18% 4	3974
April	1st to 10th	Day	54% 5% 6% 19% 13% 3	2280
	11th to 20th	Day	51% 5% 7% 20% 16% 2	2254
	21st to end	Day	55% 4 8% 15% 14% 4	2406
May	1st to 10th	Day	50% 6% 9% 21% 11% 2	4440
	11th to 20th	Day	49% 7% 13% 20% 10% 1	4402
	21st to end	Day	42% 7% 12% 22% 15% 2	4837
June	1st to 10th	Day	52% 6% 10% 19% 12% 1	2660
	11th to 20th	Day	43% 6% 11% 24% 13% 3	2660
	21st to end	Day	49% 7% 12% 20% 11% 1	2660
July	1st to 10th	Day	41% 7% 15% 24% 11% 1	4370
	11th to 20th	Day	36% 8% 16% 30% 9%	4365
	21st to end	Day	36% 8% 13% 32% 12%	4661
August	1st to 10th	Day	46% 7% 14% 23% 9%	4253
	11th to 20th	Day	42% 6% 15% 28% 8% 1	4083
	21st to end	Day	37% 7% 15% 29% 11% 1	4180
September	1st to 10th	Day	40% 7% 13% 28% 11%	2280
	11th to 20th	Day	34% 7% 14% 30% 15%	2280
	21st to end	Day	44% 6% 14% 26% 10%	2015
October	1st to 10th	Day	45% 6% 11% 30% 7%	3160
	11th to 20th	Day	46% 5% 14% 23% 12%	3140
	21st to end	Day	50% 6% 17% 21% 6%	3224
November	1st to 10th	Day	49% 5% 15% 23% 7% 1	1736
	11th to 20th	Day	55% 6% 11% 16% 10% 1	1600
	21st to end	Day	66% 5% 12% 10% 7% 1	1600
December	1st to 10th	Day	69% 5% 12% 9% 4	1528
	11th to 20th	Day	62% 6% 13% 13% 6%	1906
	21st to end	Day	72% 3 7% 14% 4	2772
January	1st to 10th	Night	65% 6% 14% 12% 3	4429
	11th to 20th	Night	63% 6% 14% 12% 4 1	4440
	21st to end	Night	69% 4 10% 10% 6% 1	4688
February	1st to 10th	Night	61% 4 11% 17% 6% 1	2470
	11th to 20th	Night	56% 5% 11% 20% 8% 1	2405
	21st to end	Night	55% 5% 10% 18% 10% 1	1907
March	1st to 10th	Night	57% 5% 9% 21% 8% 1	3652
	11th to 20th	Night	57% 6% 14% 15% 7% 1	3480
	21st to end	Night	43% 6% 8% 24% 16% 3	3658
April	1st to 10th	Night	52% 5% 8% 19% 14% 2	1900
	11th to 20th	Night	50% 4 7% 21% 16% 1	1875
	21st to end	Night	52% 5% 7% 17% 16% 3	1789
May	1st to 10th	Night	50% 8% 10% 20% 10% 3	2520
	11th to 20th	Night	45% 8% 12% 23% 11% 2	2496
	21st to end	Night	39% 7% 14% 20% 18% 2	2739
June	1st to 10th	Night	45% 8% 12% 23% 11% 1	1520
	11th to 20th	Night	39% 7% 11% 23% 17% 2	1520
	21st to end	Night	46% 8% 12% 20% 13% 1	1520
July	1st to 10th	Night	41% 9% 15% 19% 14% 2	2480
	11th to 20th	Night	36% 7% 12% 34% 10%	2472
	21st to end	Night	37% 8% 14% 26% 15%	2651
August	1st to 10th	Night	38% 7% 15% 26% 13% 1	2648
	11th to 20th	Night	39% 6% 17% 30% 8%	2812
	21st to end	Night	36% 7% 17% 26% 12% 1	3444
September	1st to 10th	Night	36% 6% 13% 30% 14% 1	1900
	11th to 20th	Night	33% 6% 14% 35% 11% 1	1900
	21st to end	Night	41% 6% 12% 30% 10% 1	2163
October	1st to 10th	Night	38% 6% 12% 30% 14%	3800
	11th to 20th	Night	41% 7% 17% 24% 10%	3779
	21st to end	Night	47% 7% 17% 21% 8%	4322
November	1st to 10th	Night	49% 6% 13% 21% 10% 1	2558
	11th to 20th	Night	54% 6% 12% 19% 9% 1	2800
	21st to end	Night	60% 6% 13% 16% 5%	2800
December	1st to 10th	Night	67% 6% 11% 13% 3	2686
	11th to 20th	Night	62% 4 10% 15% 8% 1	3288
	21st to end	Night	74% 4 7% 12% 3	4884

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	25% 20% 35% 16% 4	180
	11th to 20th	Day	32% 21% 33% 12% 3	180
	21st to end	Day	24% 19% 38% 15% 4	254
February	1st to 10th	Day	30% 27% 30% 11% 2	270
	11th to 20th	Day	27% 27% 39% 7% 1	270
	21st to end	Day	33% 22% 33% 10% 1	358
March	1st to 10th	Day	27% 19% 35% 14% 4	460
	11th to 20th	Day	28% 17% 36% 15% 3 1	460
	21st to end	Day	32% 22% 29% 12% 5% 1	506
April	1st to 10th	Day	30% 20% 32% 12% 5% 1	460
	11th to 20th	Day	34% 20% 21% 16% 7% 2	452
	21st to end	Day	30% 21% 29% 11% 7% 2	460
May	1st to 10th	Day	25% 15% 33% 19% 6% 3	463
	11th to 20th	Day	19% 16% 35% 20% 7% 2	487
	21st to end	Day	19% 14% 36% 18% 10% 3	529
June	1st to 10th	Day	23% 13% 33% 22% 8% 1	490
	11th to 20th	Day	16% 13% 35% 23% 11% 2	490
	21st to end	Day	20% 14% 33% 20% 11% 2	490
July	1st to 10th	Day	12% 8% 30% 33% 13% 3	485
	11th to 20th	Day	13% 10% 33% 28% 12% 4	484
	21st to end	Day	15% 8% 33% 30% 11% 4	532
August	1st to 10th	Day	15% 8% 29% 30% 13% 4	486
	11th to 20th	Day	13% 7% 30% 28% 16% 6%	479
	21st to end	Day	14% 11% 31% 26% 12% 7%	539
September	1st to 10th	Day	14% 15% 28% 25% 10% 7%	490
	11th to 20th	Day	12% 10% 26% 23% 18% 11%	490
	21st to end	Day	19% 13% 29% 20% 12% 5%	490
October	1st to 10th	Day	25% 16% 26% 20% 10% 4	490
	11th to 20th	Day	26% 21% 30% 16% 6% 1	490
	21st to end	Day	33% 17% 29% 18% 3 1	476
November	1st to 10th	Day	27% 18% 31% 17% 6% 1	370
	11th to 20th	Day	29% 21% 31% 13% 5% 2	200
	21st to end	Day	31% 26% 31% 9% 4	200
December	1st to 10th	Day	30% 18% 37% 12% 3	182
	11th to 20th	Day	32% 27% 28% 10% 2 1	180
	21st to end	Day	33% 22% 27% 15% 2 1	198
January	1st to 10th	Night	26% 21% 33% 17% 4	760
	11th to 20th	Night	28% 19% 30% 18% 5% 1	760
	21st to end	Night	20% 15% 37% 23% 5%	836
February	1st to 10th	Night	22% 21% 35% 19% 3	760
	11th to 20th	Night	20% 21% 41% 16% 3	743
	21st to end	Night	23% 23% 30% 20% 3	628
March	1st to 10th	Night	25% 18% 33% 20% 5%	760
	11th to 20th	Night	23% 20% 33% 18% 5% 1	760
	21st to end	Night	22% 16% 31% 23% 7%	836
April	1st to 10th	Night	28% 14% 32% 22% 4	760
	11th to 20th	Night	26% 19% 29% 19% 7%	751
	21st to end	Night	26% 14% 30% 22% 8% 1	649
May	1st to 10th	Night	22% 11% 29% 26% 11% 1	380
	11th to 20th	Night	19% 11% 35% 27% 7% 1	374
	21st to end	Night	13% 11% 35% 28% 13%	411
June	1st to 10th	Night	17% 10% 32% 32% 9%	380
	11th to 20th	Night	13% 12% 31% 31% 12% 1	380
	21st to end	Night	19% 8% 29% 31% 12%	380
July	1st to 10th	Night	7% 8% 32% 39% 14% 1	370
	11th to 20th	Night	11% 6% 27% 43% 12% 1	368
	21st to end	Night	9% 4 30% 44% 13% 1	416
August	1st to 10th	Night	11% 6% 26% 38% 19%	465
	11th to 20th	Night	12% 4 24% 35% 21% 3	564
	21st to end	Night	12% 8% 30% 30% 17% 2	817
September	1st to 10th	Night	14% 9% 31% 28% 17% 2	760
	11th to 20th	Night	16% 6% 22% 30% 22% 4	760
	21st to end	Night	19% 9% 26% 23% 21% 2	760
October	1st to 10th	Night	23% 12% 26% 24% 15% 2	760
	11th to 20th	Night	25% 14% 30% 22% 8% 1	760
	21st to end	Night	26% 18% 28% 23% 5%	836
November	1st to 10th	Night	24% 17% 29% 22% 6%	780
	11th to 20th	Night	25% 18% 33% 16% 8% 1	800
	21st to end	Night	31% 17% 28% 19% 5%	800
December	1st to 10th	Night	31% 15% 34% 17% 3 1	768
	11th to 20th	Night	28% 18% 31% 19% 4 1	760
	21st to end	Night	35% 15% 28% 18% 3	836

Page generated at 2024-11-29 10:43:05. Version ac07

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