Tollgate Creek Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tollgate Creek Park 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	5% 5% 2 5% 4 4 4 4 6% 8% 54%	105186
	Night	5% 6% 2 5% 4 3 4 3 5% 7% 55%	102582
Transparency	Day	26% 6% 11% 22% 24% 11%	104929
	Night	26% 6% 12% 24% 24% 9%	102429
Seeing	Day	8% 6% 24% 33% 22% 8%	15594
	Night	7% 3 28% 46% 15% 1	25587

By Month

Percentage Cloud Cover SW (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 4 3 7% 3 3 2 3 6% 8% 59%	2538
	11th to 20th	Day	2 6% 3 7% 3 4 4 4 5% 8% 53%	2583
	21st to end	Day	2 6% 2 6% 4 4 4 3 5% 7% 58%	3146
February	1st to 10th	Day	2 9% 4 7% 3 4 3 3 5% 7% 54%	1710
	11th to 20th	Day	2 4 3 5% 4 4 4 4 6% 7% 57%	1847
	21st to end	Day	2 8% 3 7% 3 3 3 3 6% 5% 58%	1570
March	1st to 10th	Day	3 10% 3 5% 3 3 3 3 5% 7% 54%	3130
	11th to 20th	Day	6% 9% 3 7% 4 4 3 4 5% 7% 50%	3415
	21st to end	Day	4 6% 2 6% 4 4 4 4 6% 8% 51%	4088
April	1st to 10th	Day	6% 6% 2 5% 3 3 4 4 6% 8% 53%	2280
	11th to 20th	Day	8% 9% 3 5% 4 4 5% 4 5% 6% 47%	2251
	21st to end	Day	9% 7% 2 5% 4 4 4 5% 7% 8% 46%	2280
May	1st to 10th	Day	9% 8% 2 7% 5% 5% 5% 5% 6% 8% 41%	4038
	11th to 20th	Day	10% 6% 2 5% 4 4 5% 5% 7% 9% 43%	4340
	21st to end	Day	6% 5% 2 5% 4 5% 5% 5% 6% 9% 49%	4825
June	1st to 10th	Day	5% 4 1 5% 5% 4 5% 5% 7% 9% 50%	2660
	11th to 20th	Day	6% 3 1 5% 4 4 5% 6% 7% 8% 52%	2660
	21st to end	Day	3 3 2 4 4 5% 6% 5% 8% 9% 51%	2660
July	1st to 10th	Day	5% 3 1 4 3 4 4 4 6% 8% 57%	4430
	11th to 20th	Day	3 2 1 4 3 4 6% 5% 9% 11% 50%	4430
	21st to end	Day	4 3 2 5% 4 4 5% 4 6% 9% 54%	4750
August	1st to 10th	Day	9% 5% 2 5% 5% 6% 6% 6% 8% 10% 38%	4062
	11th to 20th	Day	4 3 1 4 3 5% 5% 6% 8% 9% 52%	3726
	21st to end	Day	3 3 1 5% 3 4 5% 5% 8% 10% 52%	4180
September	1st to 10th	Day	5% 3 1 3 4 3 4 3 4 8% 61%	2280
	11th to 20th	Day	6% 3 1 4 3 4 4 4 5% 6% 61%	2245
	21st to end	Day	5% 4 1 4 2 3 3 2 4 5% 67%	2090
October	1st to 10th	Day	4 2 1 2 2 2 2 2 3 4 77%	3233
	11th to 20th	Day	4 5% 2 4 3 3 4 3 4 7% 61%	3150
	21st to end	Day	5% 6% 2 4 2 2 3 3 3 6% 65%	3291
November	1st to 10th	Day	2 4 2 3 3 3 3 3 6% 7% 64%	1709
	11th to 20th	Day	2 6% 2 5% 3 3 3 3 5% 7% 62%	1710
	21st to end	Day	4 6% 3 5% 3 3 2 3 4 7% 60%	1639
December	1st to 10th	Day	2 5% 3 6% 4 3 4 3 6% 7% 57%	1520
	11th to 20th	Day	3 5% 2 6% 4 3 4 3 6% 8% 56%	1926
	21st to end	Day	3 10% 4 8% 4 4 4 3 4 6% 51%	2794
January	1st to 10th	Night	2 8% 4 8% 4 3 3 3 5% 7% 54%	4417
	11th to 20th	Night	1 5% 1 5% 4 4 4 3 5% 7% 60%	4416
	21st to end	Night	3 6% 3 7% 5% 4 3 3 4 6% 56%	4521
February	1st to 10th	Night	2 9% 3 6% 3 4 3 3 4 7% 54%	2470
	11th to 20th	Night	2 9% 3 8% 5% 3 4 3 6% 6% 51%	2218
	21st to end	Night	3 8% 3 6% 3 4 3 3 4 6% 59%	1884
March	1st to 10th	Night	3 9% 3 5% 4 3 3 3 4 6% 58%	3734
	11th to 20th	Night	9% 12% 3 6% 3 3 3 3 4 5% 50%	3561
	21st to end	Night	6% 8% 3 6% 4 4 3 3 6% 6% 51%	3555
April	1st to 10th	Night	7% 8% 2 5% 4 4 4 3 5% 6% 53%	1900
	11th to 20th	Night	12% 8% 2 5% 3 3 4 3 5% 6% 48%	1877
	21st to end	Night	13% 8% 2 4 4 4 3 3 5% 7% 46%	1900
May	1st to 10th	Night	10% 7% 2 6% 4 4 4 3 6% 6% 45%	2928
	11th to 20th	Night	11% 5% 2 5% 4 3 5% 3 6% 10% 45%	2562
	21st to end	Night	9% 4 2 5% 4 4 4 3 7% 8% 51%	2762
June	1st to 10th	Night	5% 2 2 4 2 3 5% 4 8% 10% 55%	1520
	11th to 20th	Night	6% 3 1 2 4 3 4 4 5% 8% 59%	1520
	21st to end	Night	4 3 1 5% 4 4 4 5% 8% 8% 54%	1520
July	1st to 10th	Night	4 4 1 4 4 4 5% 4 6% 8% 56%	2540
	11th to 20th	Night	2 3 1 5% 4 4 5% 5% 8% 12% 51%	2540
	21st to end	Night	3 4 2 5% 3 4 5% 4 8% 9% 55%	2809
August	1st to 10th	Night	7% 5% 3 8% 5% 5% 6% 5% 9% 9% 39%	2877
	11th to 20th	Night	4 3 2 5% 4 4 5% 5% 9% 11% 48%	3113
	21st to end	Night	3 3 2 5% 4 5% 5% 6% 8% 11% 50%	3487
September	1st to 10th	Night	6% 4 2 5% 3 3 4 4 6% 7% 56%	1900
	11th to 20th	Night	6% 3 1 4 3 2 3 3 5% 7% 62%	1934
	21st to end	Night	6% 4 2 4 2 2 4 2 4 6% 64%	2090
October	1st to 10th	Night	5% 4 1 3 2 2 2 2 4 5% 69%	3731
	11th to 20th	Night	6% 4 2 4 3 3 3 4 5% 6% 60%	3778
	21st to end	Night	4 7% 2 3 2 2 3 3 4 6% 64%	4235
November	1st to 10th	Night	3 4 2 4 3 3 3 3 4 7% 65%	2470
	11th to 20th	Night	3 6% 1 5% 3 3 3 3 4 6% 63%	2470
	21st to end	Night	4 7% 2 5% 3 3 3 2 4 6% 60%	2539
December	1st to 10th	Night	3 6% 3 5% 3 3 3 3 4 8% 59%	2660
	11th to 20th	Night	2 7% 2 5% 3 4 4 3 6% 8% 56%	3271
	21st to end	Night	5% 10% 3 7% 4 4 4 3 5% 6% 50%	4873

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	21% 5% 12% 30% 24% 8%	2539
	11th to 20th	Day	27% 8% 12% 29% 17% 7%	2583
	21st to end	Day	24% 5% 11% 30% 24% 5%	3146
February	1st to 10th	Day	30% 4 11% 27% 19% 8%	1710
	11th to 20th	Day	25% 5% 9% 27% 27% 8%	1857
	21st to end	Day	26% 5% 8% 22% 26% 13%	1570
March	1st to 10th	Day	27% 5% 9% 18% 28% 12%	3130
	11th to 20th	Day	32% 7% 14% 27% 16% 4	3415
	21st to end	Day	27% 8% 13% 26% 22% 4	4088
April	1st to 10th	Day	27% 7% 12% 23% 22% 9%	2280
	11th to 20th	Day	35% 7% 11% 20% 18% 9%	2254
	21st to end	Day	32% 7% 13% 24% 21% 3	2280
May	1st to 10th	Day	32% 8% 13% 25% 17% 6%	4038
	11th to 20th	Day	33% 10% 13% 23% 19% 3	4344
	21st to end	Day	25% 10% 14% 23% 19% 8%	4825
June	1st to 10th	Day	26% 9% 15% 23% 18% 9%	2660
	11th to 20th	Day	25% 8% 12% 16% 22% 17%	2660
	21st to end	Day	25% 7% 13% 19% 24% 13%	2660
July	1st to 10th	Day	22% 7% 9% 15% 29% 19%	4361
	11th to 20th	Day	22% 8% 12% 22% 23% 13%	4355
	21st to end	Day	25% 7% 11% 18% 20% 19%	4600
August	1st to 10th	Day	35% 9% 16% 20% 14% 5%	4048
	11th to 20th	Day	25% 7% 15% 16% 21% 15%	3762
	21st to end	Day	24% 6% 12% 20% 26% 13%	4179
September	1st to 10th	Day	22% 4 9% 20% 25% 19%	2280
	11th to 20th	Day	21% 6% 9% 18% 27% 19%	2245
	21st to end	Day	20% 3 8% 18% 36% 15%	2090
October	1st to 10th	Day	13% 3 5% 15% 37% 26%	3233
	11th to 20th	Day	23% 4 8% 23% 33% 9%	3150
	21st to end	Day	22% 3 5% 22% 35% 13%	3291
November	1st to 10th	Day	18% 4 9% 25% 28% 16%	1709
	11th to 20th	Day	22% 5% 7% 25% 33% 9%	1710
	21st to end	Day	24% 4 8% 21% 28% 16%	1639
December	1st to 10th	Day	24% 6% 11% 29% 22% 9%	1520
	11th to 20th	Day	24% 5% 11% 23% 30% 7%	1924
	21st to end	Day	32% 5% 9% 23% 24% 8%	2794
January	1st to 10th	Night	27% 5% 10% 26% 27% 5%	4417
	11th to 20th	Night	21% 8% 14% 25% 22% 11%	4416
	21st to end	Night	28% 6% 10% 31% 18% 6%	4521
February	1st to 10th	Night	29% 5% 10% 25% 23% 7%	2470
	11th to 20th	Night	32% 4 9% 26% 22% 7%	2218
	21st to end	Night	25% 3 8% 24% 26% 13%	1884
March	1st to 10th	Night	25% 4 8% 20% 33% 10%	3734
	11th to 20th	Night	32% 7% 14% 17% 26% 4	3561
	21st to end	Night	29% 8% 11% 31% 19% 3	3555
April	1st to 10th	Night	30% 6% 11% 21% 22% 10%	1900
	11th to 20th	Night	36% 4 12% 22% 18% 8%	1877
	21st to end	Night	36% 6% 11% 25% 18% 4	1900
May	1st to 10th	Night	33% 9% 13% 23% 13% 8%	2928
	11th to 20th	Night	32% 10% 16% 25% 13% 4	2563
	21st to end	Night	25% 9% 21% 21% 17% 6%	2762
June	1st to 10th	Night	20% 7% 20% 30% 14% 8%	1520
	11th to 20th	Night	20% 6% 15% 21% 23% 15%	1520
	21st to end	Night	23% 8% 12% 23% 26% 8%	1520
July	1st to 10th	Night	24% 7% 13% 18% 30% 8%	2500
	11th to 20th	Night	23% 7% 16% 27% 21% 6%	2492
	21st to end	Night	22% 7% 14% 22% 21% 14%	2721
August	1st to 10th	Night	37% 8% 15% 22% 13% 4	2868
	11th to 20th	Night	26% 8% 19% 19% 18% 9%	3143
	21st to end	Night	25% 6% 15% 26% 23% 5%	3487
September	1st to 10th	Night	25% 6% 10% 21% 25% 14%	1900
	11th to 20th	Night	19% 6% 11% 23% 25% 16%	1934
	21st to end	Night	22% 4 9% 20% 33% 12%	2090
October	1st to 10th	Night	17% 4 7% 19% 31% 21%	3731
	11th to 20th	Night	24% 4 10% 26% 27% 10%	3778
	21st to end	Night	22% 3 5% 25% 31% 14%	4235
November	1st to 10th	Night	18% 4 10% 24% 29% 16%	2470
	11th to 20th	Night	21% 4 8% 26% 32% 10%	2470
	21st to end	Night	26% 3 8% 22% 30% 11%	2539
December	1st to 10th	Night	24% 4 12% 27% 25% 9%	2660
	11th to 20th	Night	23% 5% 10% 24% 31% 6%	3272
	21st to end	Night	33% 4 10% 24% 23% 6%	4873

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	4 6% 24% 44% 17% 5%	270
	11th to 20th	Day	9% 5% 30% 41% 14% 1	270
	21st to end	Day	3 5% 32% 44% 14% 2	297
February	1st to 10th	Day	5% 9% 37% 39% 8% 2	270
	11th to 20th	Day	4 4 38% 42% 11% 2	270
	21st to end	Day	4 8% 41% 34% 12%	225
March	1st to 10th	Day	4 7% 32% 36% 15% 6%	270
	11th to 20th	Day	10% 10% 32% 31% 13% 4	411
	21st to end	Day	13% 15% 33% 26% 10% 2	506
April	1st to 10th	Day	10% 13% 33% 30% 11% 3	460
	11th to 20th	Day	13% 19% 30% 24% 11% 3	452
	21st to end	Day	16% 12% 29% 25% 15% 3	460
May	1st to 10th	Day	15% 9% 30% 29% 14% 3	597
	11th to 20th	Day	16% 7% 21% 30% 21% 5%	675
	21st to end	Day	11% 8% 22% 31% 19% 8%	734
June	1st to 10th	Day	6% 4 18% 34% 26% 12%	680
	11th to 20th	Day	6% 4 27% 34% 24% 5%	680
	21st to end	Day	6% 4 20% 35% 27% 8%	680
July	1st to 10th	Day	7% 2 15% 26% 36% 13%	671
	11th to 20th	Day	4 2 12% 30% 38% 15%	668
	21st to end	Day	5% 1 11% 28% 38% 16%	711
August	1st to 10th	Day	9% 2 17% 29% 28% 16%	487
	11th to 20th	Day	5% 3 15% 35% 29% 14%	477
	21st to end	Day	6% 2 17% 32% 30% 12%	539
September	1st to 10th	Day	6% 3 16% 32% 28% 15%	490
	11th to 20th	Day	5% 4 21% 31% 28% 11%	455
	21st to end	Day	7% 4 19% 28% 28% 14%	300
October	1st to 10th	Day	10% 3 20% 21% 28% 17%	300
	11th to 20th	Day	2 5% 23% 38% 25% 7%	300
	21st to end	Day	10% 7% 23% 37% 18% 5%	330
November	1st to 10th	Day	4 10% 20% 39% 22% 6%	282
	11th to 20th	Day	6% 5% 28% 39% 18% 4	270
	21st to end	Day	7% 6% 29% 40% 16% 3	270
December	1st to 10th	Day	3 9% 34% 34% 19% 1	270
	11th to 20th	Day	6% 4 30% 47% 12%	270
	21st to end	Day	5% 7% 34% 42% 10% 2	297
January	1st to 10th	Night	5% 3 33% 45% 12% 2	950
	11th to 20th	Night	5% 4 36% 45% 9% 1	936
	21st to end	Night	6% 3 32% 47% 11% 1	836
February	1st to 10th	Night	6% 2 42% 43% 7%	760
	11th to 20th	Night	5% 3 38% 46% 8%	744
	21st to end	Night	5% 5% 39% 48% 3	628
March	1st to 10th	Night	5% 4 38% 44% 9%	760
	11th to 20th	Night	10% 5% 29% 45% 11%	760
	21st to end	Night	9% 6% 36% 41% 8%	679
April	1st to 10th	Night	11% 7% 37% 39% 5%	570
	11th to 20th	Night	16% 9% 32% 36% 7%	563
	21st to end	Night	17% 4 30% 40% 9%	570
May	1st to 10th	Night	14% 6% 29% 40% 10% 1	570
	11th to 20th	Night	16% 4 20% 44% 16% 1	561
	21st to end	Night	10% 4 27% 41% 17% 1	617
June	1st to 10th	Night	5% 2 19% 48% 24% 2	570
	11th to 20th	Night	6% 2 25% 51% 16% 1	570
	21st to end	Night	5% 2 20% 49% 23% 1	570
July	1st to 10th	Night	8% 1 15% 47% 28% 1	555
	11th to 20th	Night	3 1 13% 46% 34% 2	552
	21st to end	Night	6% 1 10% 45% 35% 2	624
August	1st to 10th	Night	7% 2 12% 48% 30% 1	567
	11th to 20th	Night	5% 2 16% 51% 24% 1	564
	21st to end	Night	6% 1 16% 52% 22% 2	627
September	1st to 10th	Night	7% 1 16% 50% 22% 3	570
	11th to 20th	Night	8% 2 19% 47% 23% 2	570
	21st to end	Night	8% 1 21% 47% 22% 1	570
October	1st to 10th	Night	11% 3 23% 42% 18% 3	717
	11th to 20th	Night	6% 2 28% 45% 18% 2	760
	21st to end	Night	9% 4 25% 44% 16% 1	902
November	1st to 10th	Night	4 3 29% 49% 13% 2	950
	11th to 20th	Night	6% 3 31% 49% 9% 1	950
	21st to end	Night	7% 4 28% 46% 14% 1	950
December	1st to 10th	Night	6% 3 35% 46% 10%	950
	11th to 20th	Night	5% 3 34% 48% 10% 1	950
	21st to end	Night	7% 4 35% 44% 9% 1	1045

Page generated at 2024-11-03 00:11:17. Version ac07

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