Dr. T. K. Lawless Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dr. T. K. Lawless Park clear sky chart from 2005-11-06 to 2024-11-11.

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% 10% 4 8% 5% 4 5% 4 5% 7% 34%	101224
	Night	15% 11% 4 9% 5% 4 4 3 5% 6% 33%	98002
Transparency	Day	47% 6% 11% 21% 13% 1	104823
	Night	50% 5% 11% 20% 13% 1	102544
Seeing	Day	17% 10% 28% 24% 15% 6%	15766
	Night	19% 8% 28% 30% 12% 1	25608

By Month

Percentage Cloud Cover SE (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	15% 21% 8% 11% 7% 5% 5% 3 4 5% 15%	2527
	11th to 20th	Day	15% 18% 8% 15% 8% 6% 10% 4 4 3 9%	2530
	21st to end	Day	25% 24% 9% 13% 5% 4 3 2 2 4 9%	2783
February	1st to 10th	Day	15% 15% 6% 12% 10% 6% 5% 3 4 5% 18%	1814
	11th to 20th	Day	15% 13% 6% 16% 8% 5% 4 3 4 5% 22%	1848
	21st to end	Day	16% 16% 6% 13% 4 5% 5% 4 5% 6% 21%	1570
March	1st to 10th	Day	17% 13% 7% 8% 5% 5% 4 3 5% 6% 28%	3120
	11th to 20th	Day	11% 9% 8% 8% 6% 5% 5% 4 6% 8% 31%	3374
	21st to end	Day	20% 13% 6% 11% 6% 5% 4 3 4 5% 23%	3968
April	1st to 10th	Day	18% 14% 3 8% 5% 5% 4 2 6% 6% 30%	2280
	11th to 20th	Day	16% 11% 3 6% 4 4 4 3 5% 7% 36%	2282
	21st to end	Day	19% 9% 2 8% 5% 4 3 3 5% 7% 35%	2470
May	1st to 10th	Day	18% 8% 2 7% 4 5% 5% 4 6% 7% 34%	4082
	11th to 20th	Day	15% 7% 2 7% 4 4 4 4 6% 8% 39%	4081
	21st to end	Day	10% 5% 2 6% 4 4 5% 4 5% 9% 45%	4753
June	1st to 10th	Day	9% 6% 2 6% 5% 4 4 4 7% 8% 44%	2660
	11th to 20th	Day	10% 6% 1 5% 5% 5% 5% 5% 7% 8% 43%	2660
	21st to end	Day	10% 6% 2 6% 5% 5% 5% 5% 7% 8% 40%	2660
July	1st to 10th	Day	11% 7% 3 7% 5% 5% 6% 4 6% 9% 36%	4440
	11th to 20th	Day	7% 5% 2 5% 3 4 4 4 6% 10% 50%	4440
	21st to end	Day	7% 5% 2 7% 5% 5% 6% 5% 7% 8% 43%	4796
August	1st to 10th	Day	11% 4 2 6% 4 4 4 4 6% 8% 47%	4104
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 6% 7% 46%	4021
	21st to end	Day	8% 5% 2 5% 4 4 5% 4 6% 10% 47%	4180
September	1st to 10th	Day	10% 6% 3 6% 4 4 3 4 5% 9% 46%	2252
	11th to 20th	Day	11% 5% 2 5% 3 4 5% 4 6% 8% 48%	2090
	21st to end	Day	14% 7% 3 6% 5% 3 4 3 6% 8% 40%	2090
October	1st to 10th	Day	13% 7% 2 7% 5% 4 4 3 5% 6% 43%	2090
	11th to 20th	Day	18% 8% 3 8% 4 5% 5% 3 5% 7% 33%	1877
	21st to end	Day	21% 11% 4 9% 6% 4 4 4 5% 7% 26%	1881
November	1st to 10th	Day	12% 12% 4 7% 4 4 4 3 6% 7% 38%	1762
	11th to 20th	Day	16% 18% 5% 9% 5% 4 4 3 5% 5% 24%	1710
	21st to end	Day	21% 16% 6% 9% 5% 3 4 3 4 5% 23%	1710
December	1st to 10th	Day	15% 20% 8% 11% 6% 4 3 3 4 6% 21%	1618
	11th to 20th	Day	12% 22% 10% 13% 6% 3 4 4 4 5% 18%	1918
	21st to end	Day	23% 21% 7% 14% 6% 4 4 3 4 5% 11%	2783
January	1st to 10th	Night	16% 18% 9% 13% 7% 5% 4 3 4 5% 15%	4428
	11th to 20th	Night	15% 18% 10% 17% 6% 4 7% 4 4 4 11%	4440
	21st to end	Night	26% 18% 9% 13% 6% 4 3 3 3 4 11%	4882
February	1st to 10th	Night	17% 15% 5% 12% 8% 5% 4 2 5% 5% 21%	2361
	11th to 20th	Night	14% 13% 5% 11% 7% 6% 5% 3 5% 6% 25%	2218
	21st to end	Night	19% 13% 4 11% 5% 4 4 4 5% 5% 26%	1884
March	1st to 10th	Night	16% 12% 5% 8% 4 4 3 3 4 6% 34%	3733
	11th to 20th	Night	11% 7% 4 7% 5% 6% 4 4 5% 7% 42%	3585
	21st to end	Night	20% 11% 5% 11% 5% 4 4 3 4 5% 29%	3692
April	1st to 10th	Night	15% 11% 3 6% 5% 5% 5% 4 5% 7% 35%	1900
	11th to 20th	Night	19% 9% 2 6% 5% 4 5% 3 5% 5% 37%	1847
	21st to end	Night	19% 8% 2 7% 5% 4 4 4 5% 7% 36%	1710
May	1st to 10th	Night	15% 9% 3 7% 5% 5% 5% 4 7% 8% 33%	2813
	11th to 20th	Night	19% 8% 2 5% 3 3 4 3 4 7% 43%	2812
	21st to end	Night	14% 6% 2 7% 4 4 4 4 5% 7% 43%	2808
June	1st to 10th	Night	10% 5% 2 5% 4 4 4 4 7% 10% 47%	1520
	11th to 20th	Night	9% 6% 2 6% 5% 4 5% 5% 7% 9% 44%	1520
	21st to end	Night	10% 5% 2 5% 5% 4 4 4 7% 10% 42%	1520
July	1st to 10th	Night	9% 4 2 6% 4 4 6% 5% 7% 9% 44%	2530
	11th to 20th	Night	7% 4 1 5% 3 4 3 3 6% 8% 57%	2530
	21st to end	Night	7% 5% 2 5% 4 4 5% 4 7% 10% 46%	2765
August	1st to 10th	Night	10% 5% 2 6% 4 4 4 4 7% 8% 46%	2825
	11th to 20th	Night	10% 5% 1 5% 4 4 4 4 6% 8% 50%	2805
	21st to end	Night	9% 5% 2 6% 3 4 4 4 5% 8% 48%	3476
September	1st to 10th	Night	10% 6% 2 5% 4 4 3 4 5% 7% 50%	1909
	11th to 20th	Night	10% 4 1 5% 4 4 3 3 5% 7% 55%	2090
	21st to end	Night	15% 6% 2 6% 4 4 3 3 5% 8% 43%	2090
October	1st to 10th	Night	14% 7% 2 5% 4 3 4 3 4 6% 47%	2090
	11th to 20th	Night	17% 10% 3 8% 4 4 3 3 5% 6% 37%	2297
	21st to end	Night	22% 11% 3 7% 4 4 4 3 4 5% 33%	2717
November	1st to 10th	Night	14% 10% 3 7% 5% 4 4 3 5% 6% 39%	2536
	11th to 20th	Night	15% 15% 5% 10% 5% 4 5% 4 6% 5% 27%	2477
	21st to end	Night	18% 18% 4 9% 5% 4 3 3 5% 6% 25%	2470
December	1st to 10th	Night	17% 20% 6% 12% 5% 5% 4 3 4 5% 18%	2559
	11th to 20th	Night	15% 17% 8% 13% 7% 4 4 3 4 4 18%	3279
	21st to end	Night	27% 19% 7% 10% 5% 4 4 3 4 4 12%	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	69% 6% 13% 10% 2	2528
	11th to 20th	Day	75% 4 11% 8% 2	2530
	21st to end	Day	81% 3 5% 8% 2	2783
February	1st to 10th	Day	68% 5% 9% 12% 6% 1	1814
	11th to 20th	Day	65% 4 8% 14% 8%	1858
	21st to end	Day	64% 5% 11% 13% 7% 1	1570
March	1st to 10th	Day	56% 6% 10% 20% 7%	3120
	11th to 20th	Day	50% 5% 13% 24% 7% 1	3374
	21st to end	Day	64% 6% 8% 18% 4	3968
April	1st to 10th	Day	54% 5% 9% 20% 11%	2280
	11th to 20th	Day	48% 5% 10% 22% 13% 3	2282
	21st to end	Day	49% 5% 11% 19% 14% 2	2470
May	1st to 10th	Day	46% 8% 11% 23% 11% 1	4120
	11th to 20th	Day	42% 7% 13% 27% 11% 1	4085
	21st to end	Day	35% 8% 10% 22% 24% 1	4766
June	1st to 10th	Day	36% 7% 11% 26% 18% 2	2660
	11th to 20th	Day	35% 8% 11% 25% 19% 3	2660
	21st to end	Day	39% 7% 14% 21% 16% 3	2660
July	1st to 10th	Day	44% 6% 13% 19% 16% 3	4371
	11th to 20th	Day	29% 6% 15% 32% 17% 2	4365
	21st to end	Day	36% 8% 14% 19% 21% 2	4645
August	1st to 10th	Day	35% 6% 14% 27% 17% 1	4091
	11th to 20th	Day	34% 7% 11% 30% 16% 1	4060
	21st to end	Day	32% 7% 13% 28% 18% 3	4179
September	1st to 10th	Day	35% 6% 15% 23% 18% 3	2252
	11th to 20th	Day	33% 5% 11% 28% 20% 2	2090
	21st to end	Day	42% 5% 10% 24% 17% 1	2090
October	1st to 10th	Day	30% 4 9% 37% 18% 1	3480
	11th to 20th	Day	41% 4 10% 22% 23%	3093
	21st to end	Day	49% 3 10% 25% 11% 2	3081
November	1st to 10th	Day	45% 4 13% 23% 14% 1	1762
	11th to 20th	Day	61% 4 11% 17% 7% 1	1710
	21st to end	Day	64% 5% 11% 15% 5%	1710
December	1st to 10th	Day	66% 3 12% 14% 4	1618
	11th to 20th	Day	69% 5% 12% 13% 2	1915
	21st to end	Day	78% 4 8% 7% 3	2783
January	1st to 10th	Night	70% 5% 9% 11% 4	4428
	11th to 20th	Night	76% 5% 10% 7% 3	4440
	21st to end	Night	77% 4 8% 8% 2	4882
February	1st to 10th	Night	65% 4 10% 13% 6% 1	2361
	11th to 20th	Night	60% 3 10% 18% 8%	2219
	21st to end	Night	60% 5% 11% 16% 7% 2	1884
March	1st to 10th	Night	52% 5% 11% 25% 7% 1	3733
	11th to 20th	Night	42% 6% 11% 25% 14% 2	3585
	21st to end	Night	57% 5% 12% 17% 7% 1	3692
April	1st to 10th	Night	48% 5% 12% 21% 13% 1	1900
	11th to 20th	Night	49% 4 8% 19% 18% 2	1847
	21st to end	Night	47% 6% 10% 20% 15% 2	1710
May	1st to 10th	Night	46% 7% 10% 24% 12% 1	2840
	11th to 20th	Night	42% 6% 10% 26% 15% 1	2813
	21st to end	Night	38% 8% 11% 19% 21% 3	2816
June	1st to 10th	Night	32% 6% 11% 30% 18% 3	1520
	11th to 20th	Night	34% 7% 13% 24% 19% 2	1520
	21st to end	Night	35% 7% 17% 23% 15% 3	1520
July	1st to 10th	Night	34% 7% 15% 25% 13% 7%	2490
	11th to 20th	Night	25% 5% 14% 28% 25% 3	2482
	21st to end	Night	33% 7% 15% 17% 25% 3	2677
August	1st to 10th	Night	34% 8% 13% 29% 16% 1	2814
	11th to 20th	Night	30% 7% 12% 30% 18% 1	2832
	21st to end	Night	34% 6% 9% 29% 19% 3	3476
September	1st to 10th	Night	34% 6% 11% 24% 21% 4	1909
	11th to 20th	Night	30% 3 8% 32% 25% 2	2090
	21st to end	Night	40% 5% 10% 27% 17% 1	2090
October	1st to 10th	Night	27% 4 9% 33% 26% 1	3480
	11th to 20th	Night	39% 4 9% 25% 23%	3820
	21st to end	Night	41% 4 9% 29% 17% 1	4467
November	1st to 10th	Night	46% 5% 10% 24% 15% 1	2536
	11th to 20th	Night	56% 4 13% 17% 8% 1	2477
	21st to end	Night	60% 4 12% 18% 5%	2470
December	1st to 10th	Night	68% 4 10% 12% 5%	2559
	11th to 20th	Night	69% 4 11% 12% 3	3281
	21st to end	Night	76% 5% 10% 7% 2	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	23% 18% 31% 20% 7% 1	270
	11th to 20th	Day	23% 15% 38% 17% 6% 1	270
	21st to end	Day	26% 15% 30% 24% 5%	297
February	1st to 10th	Day	24% 20% 29% 21% 6% 1	270
	11th to 20th	Day	25% 18% 33% 20% 4	270
	21st to end	Day	25% 20% 40% 12% 4	225
March	1st to 10th	Day	20% 22% 38% 14% 5%	270
	11th to 20th	Day	22% 17% 29% 23% 8% 1	393
	21st to end	Day	30% 12% 30% 21% 7% 1	506
April	1st to 10th	Day	25% 12% 33% 22% 8% 1	460
	11th to 20th	Day	22% 18% 29% 19% 10% 3	452
	21st to end	Day	23% 12% 34% 19% 9% 2	460
May	1st to 10th	Day	25% 10% 31% 21% 10% 3	463
	11th to 20th	Day	22% 10% 24% 24% 14% 5%	487
	21st to end	Day	12% 7% 27% 27% 19% 7%	689
June	1st to 10th	Day	10% 9% 27% 31% 17% 5%	680
	11th to 20th	Day	13% 6% 29% 29% 17% 6%	680
	21st to end	Day	14% 7% 28% 28% 17% 6%	680
July	1st to 10th	Day	9% 4 21% 28% 23% 15%	671
	11th to 20th	Day	10% 4 26% 28% 22% 11%	668
	21st to end	Day	7% 4 21% 35% 23% 10%	734
August	1st to 10th	Day	9% 3 16% 29% 25% 17%	486
	11th to 20th	Day	10% 4 20% 31% 25% 10%	479
	21st to end	Day	10% 4 18% 29% 28% 11%	539
September	1st to 10th	Day	12% 7% 21% 26% 24% 10%	490
	11th to 20th	Day	9% 3 19% 24% 30% 15%	490
	21st to end	Day	17% 11% 21% 24% 18% 8%	490
October	1st to 10th	Day	15% 8% 27% 27% 17% 6%	490
	11th to 20th	Day	23% 17% 26% 26% 9% 1	400
	21st to end	Day	30% 13% 35% 17% 4 2	330
November	1st to 10th	Day	17% 16% 33% 22% 8% 3	300
	11th to 20th	Day	24% 17% 32% 19% 7%	270
	21st to end	Day	29% 12% 39% 17% 3	270
December	1st to 10th	Day	23% 22% 33% 13% 7% 1	270
	11th to 20th	Day	21% 19% 38% 18% 4	270
	21st to end	Day	22% 23% 39% 15% 2	297
January	1st to 10th	Night	22% 15% 34% 23% 6%	950
	11th to 20th	Night	25% 13% 33% 23% 5% 1	950
	21st to end	Night	21% 11% 37% 27% 4	1043
February	1st to 10th	Night	25% 9% 36% 26% 4	760
	11th to 20th	Night	20% 14% 36% 26% 4	743
	21st to end	Night	26% 11% 36% 23% 4	628
March	1st to 10th	Night	22% 11% 35% 24% 7% 1	760
	11th to 20th	Night	18% 11% 37% 26% 7% 1	760
	21st to end	Night	25% 10% 28% 31% 5% 1	762
April	1st to 10th	Night	19% 12% 34% 29% 6% 1	570
	11th to 20th	Night	24% 9% 34% 27% 6% 1	563
	21st to end	Night	22% 7% 33% 28% 9%	570
May	1st to 10th	Night	21% 5% 31% 35% 8% 1	570
	11th to 20th	Night	23% 4 26% 32% 14% 1	561
	21st to end	Night	14% 3 24% 38% 19% 1	617
June	1st to 10th	Night	11% 3 24% 44% 17% 1	570
	11th to 20th	Night	13% 2 25% 42% 17% 1	570
	21st to end	Night	11% 2 21% 41% 23% 2	570
July	1st to 10th	Night	8% 3 16% 41% 28% 4	555
	11th to 20th	Night	10% 3 16% 40% 28% 4	552
	21st to end	Night	6% 2 15% 42% 33% 2	624
August	1st to 10th	Night	9% 2 11% 46% 29% 4	567
	11th to 20th	Night	9% 1 15% 42% 27% 5%	564
	21st to end	Night	10% 2 14% 37% 34% 4	627
September	1st to 10th	Night	12% 2 16% 39% 28% 4	579
	11th to 20th	Night	11% 2 17% 37% 28% 5%	760
	21st to end	Night	18% 5% 23% 30% 19% 5%	760
October	1st to 10th	Night	16% 6% 24% 34% 18% 2	760
	11th to 20th	Night	23% 11% 28% 28% 10%	760
	21st to end	Night	27% 12% 31% 24% 7%	836
November	1st to 10th	Night	21% 10% 32% 26% 10% 1	780
	11th to 20th	Night	23% 14% 33% 23% 6% 1	763
	21st to end	Night	26% 10% 33% 26% 4	760
December	1st to 10th	Night	25% 14% 36% 20% 5%	849
	11th to 20th	Night	23% 13% 37% 23% 4	950
	21st to end	Night	31% 14% 31% 21% 2	1045

Page generated at 2024-11-08 06:44:49. Version ac07

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