Tucker Creek Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tucker Creek Observatory clear sky chart from 2005-11-06 to 2024-01-22.

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	12% 7% 3 5% 5% 3 5% 5% 5% 7% 43%	74822
	Night	13% 7% 3 5% 5% 3 4 4 5% 7% 46%	75128
Transparency	Day	39% 6% 12% 24% 16% 3	74533
	Night	38% 5% 11% 24% 18% 4	74938
Seeing	Day	16% 11% 27% 25% 15% 5%	14403
	Night	17% 11% 29% 27% 14% 2	24353

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% 9% 4 6% 5% 3 4 4 3 6% 41%	1517
	11th to 20th	Day	17% 9% 4 6% 5% 3 4 3 5% 5% 39%	1675
	21st to end	Day	12% 10% 3 7% 5% 3 5% 4 3 6% 42%	1791
February	1st to 10th	Day	17% 11% 3 7% 5% 3 4 3 4 5% 38%	1649
	11th to 20th	Day	15% 8% 4 6% 6% 2 4 4 6% 7% 39%	1748
	21st to end	Day	15% 11% 3 6% 5% 3 4 5% 5% 6% 37%	1480
March	1st to 10th	Day	15% 8% 3 6% 3 2 4 4 4 5% 45%	1813
	11th to 20th	Day	19% 9% 4 6% 5% 3 4 4 4 5% 36%	1980
	21st to end	Day	19% 10% 5% 7% 6% 3 5% 4 5% 6% 31%	2301
April	1st to 10th	Day	10% 7% 3 4 4 3 4 5% 6% 7% 46%	2160
	11th to 20th	Day	16% 9% 3 6% 4 3 4 4 4 7% 41%	2134
	21st to end	Day	18% 8% 3 5% 5% 3 5% 5% 4 7% 38%	2160
May	1st to 10th	Day	15% 7% 2 6% 6% 3 4 5% 6% 7% 38%	2186
	11th to 20th	Day	16% 6% 2 5% 5% 3 5% 5% 5% 8% 40%	2377
	21st to end	Day	9% 6% 3 6% 7% 4 7% 6% 6% 9% 36%	2725
June	1st to 10th	Day	9% 5% 2 5% 6% 3 5% 4 7% 8% 46%	2520
	11th to 20th	Day	4 4 2 5% 5% 4 6% 6% 7% 9% 49%	2520
	21st to end	Day	4 3 2 4 5% 4 6% 5% 8% 11% 47%	2520
July	1st to 10th	Day	9% 5% 2 5% 5% 4 5% 6% 7% 9% 42%	2520
	11th to 20th	Day	5% 3 1 5% 6% 3 6% 6% 8% 11% 46%	2520
	21st to end	Day	6% 5% 2 5% 6% 4 7% 6% 7% 8% 43%	2574
August	1st to 10th	Day	7% 4 2 5% 5% 4 6% 7% 7% 11% 42%	2270
	11th to 20th	Day	10% 5% 2 5% 6% 4 6% 5% 7% 11% 40%	2125
	21st to end	Day	7% 5% 2 5% 6% 3 6% 6% 7% 9% 45%	2376
September	1st to 10th	Day	11% 5% 2 5% 5% 3 5% 4 6% 8% 47%	2160
	11th to 20th	Day	8% 6% 2 5% 5% 3 4 5% 5% 9% 47%	2123
	21st to end	Day	11% 4 2 3 3 2 4 4 5% 8% 54%	1980
October	1st to 10th	Day	8% 4 2 4 4 3 4 4 5% 6% 56%	1825
	11th to 20th	Day	14% 5% 2 4 4 3 2 4 4 6% 52%	1800
	21st to end	Day	17% 8% 2 5% 4 2 3 3 4 5% 47%	1975
November	1st to 10th	Day	11% 5% 2 5% 3 3 3 3 4 5% 56%	1672
	11th to 20th	Day	12% 7% 3 5% 5% 2 4 4 4 8% 47%	1710
	21st to end	Day	17% 9% 3 6% 4 2 3 4 4 4 43%	1710
December	1st to 10th	Day	14% 9% 3 6% 6% 2 4 3 4 7% 41%	1525
	11th to 20th	Day	16% 9% 4 6% 6% 3 4 4 4 5% 39%	1918
	21st to end	Day	17% 13% 4 7% 6% 3 4 4 5% 5% 31%	2783
January	1st to 10th	Night	14% 10% 4 6% 5% 2 4 4 5% 6% 41%	2648
	11th to 20th	Night	18% 9% 3 6% 5% 3 4 4 4 5% 38%	2503
	21st to end	Night	14% 8% 3 6% 6% 3 5% 4 4 6% 41%	2600
February	1st to 10th	Night	18% 11% 5% 7% 4 3 3 3 4 6% 36%	2308
	11th to 20th	Night	15% 7% 4 7% 5% 3 4 4 4 5% 43%	2098
	21st to end	Night	18% 7% 4 6% 4 2 4 5% 5% 5% 39%	1776
March	1st to 10th	Night	18% 8% 3 5% 5% 2 4 4 5% 5% 42%	2160
	11th to 20th	Night	18% 7% 4 7% 4 3 4 4 5% 6% 38%	1980
	21st to end	Night	19% 8% 3 7% 5% 3 4 5% 5% 6% 34%	2054
April	1st to 10th	Night	10% 5% 2 5% 4 3 5% 4 5% 8% 49%	1800
	11th to 20th	Night	13% 6% 2 6% 5% 4 4 5% 5% 7% 44%	1775
	21st to end	Night	20% 7% 3 5% 5% 3 4 3 4 6% 41%	1800
May	1st to 10th	Night	14% 7% 2 4 5% 3 4 4 5% 7% 44%	1769
	11th to 20th	Night	15% 6% 3 5% 6% 2 4 4 5% 6% 44%	1514
	21st to end	Night	10% 5% 3 6% 6% 4 5% 6% 7% 9% 41%	1551
June	1st to 10th	Night	8% 5% 2 6% 5% 2 6% 5% 5% 10% 46%	1440
	11th to 20th	Night	5% 3 1 4 3 2 4 4 6% 10% 57%	1440
	21st to end	Night	4 2 1 3 3 3 5% 6% 7% 10% 55%	1440
July	1st to 10th	Night	6% 3 2 5% 5% 3 5% 4 6% 9% 53%	1440
	11th to 20th	Night	6% 3 2 5% 4 2 4 4 6% 9% 55%	1440
	21st to end	Night	5% 5% 2 4 4 2 5% 6% 8% 10% 49%	1741
August	1st to 10th	Night	6% 3 1 4 5% 3 5% 6% 7% 11% 49%	1666
	11th to 20th	Night	7% 5% 2 5% 5% 3 4 4 5% 8% 53%	1776
	21st to end	Night	6% 4 2 5% 4 2 4 5% 6% 9% 53%	1980
September	1st to 10th	Night	10% 5% 2 5% 5% 3 4 4 4 6% 53%	1800
	11th to 20th	Night	8% 5% 2 4 4 3 5% 5% 5% 6% 53%	1818
	21st to end	Night	9% 4 2 3 4 3 4 5% 5% 7% 55%	1980
October	1st to 10th	Night	7% 4 1 4 4 2 3 3 5% 6% 62%	2132
	11th to 20th	Night	13% 5% 2 4 4 2 3 3 4 5% 55%	2160
	21st to end	Night	18% 7% 3 5% 3 2 3 3 4 4 47%	2380
November	1st to 10th	Night	10% 6% 2 3 3 1 3 3 5% 6% 58%	2406
	11th to 20th	Night	13% 6% 2 4 4 3 4 3 4 6% 52%	2470
	21st to end	Night	18% 8% 3 4 4 2 3 3 4 5% 47%	2470
December	1st to 10th	Night	17% 9% 3 5% 4 3 4 4 5% 7% 40%	2650
	11th to 20th	Night	15% 8% 3 5% 5% 3 5% 4 4 6% 42%	3279
	21st to end	Night	16% 12% 5% 8% 7% 3 5% 4 4 6% 30%	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	46% 4 10% 23% 14% 4	1518
	11th to 20th	Day	48% 3 10% 25% 12% 2	1675
	21st to end	Day	43% 4 12% 24% 14% 3	1791
February	1st to 10th	Day	49% 4 10% 22% 14% 1	1649
	11th to 20th	Day	45% 5% 12% 21% 13% 5%	1758
	21st to end	Day	48% 5% 9% 22% 12% 5%	1480
March	1st to 10th	Day	43% 4 8% 23% 17% 5%	1813
	11th to 20th	Day	50% 5% 9% 18% 14% 3	1980
	21st to end	Day	53% 6% 12% 18% 10% 1	2301
April	1st to 10th	Day	36% 6% 11% 26% 19% 2	2160
	11th to 20th	Day	44% 5% 10% 21% 16% 4	2134
	21st to end	Day	45% 6% 11% 22% 15% 1	2160
May	1st to 10th	Day	44% 7% 14% 23% 12% 1	2186
	11th to 20th	Day	41% 7% 14% 21% 15% 2	2381
	21st to end	Day	43% 9% 14% 21% 12% 1	2725
June	1st to 10th	Day	33% 7% 16% 25% 17% 1	2520
	11th to 20th	Day	29% 8% 13% 26% 21% 3	2520
	21st to end	Day	28% 8% 17% 24% 17% 5%	2520
July	1st to 10th	Day	35% 8% 15% 23% 14% 4	2451
	11th to 20th	Day	29% 8% 16% 27% 16% 3	2445
	21st to end	Day	34% 9% 13% 29% 12% 2	2431
August	1st to 10th	Day	32% 10% 16% 28% 14% 1	2256
	11th to 20th	Day	36% 9% 14% 27% 13% 1	2125
	21st to end	Day	32% 7% 17% 21% 17% 5%	2376
September	1st to 10th	Day	33% 6% 13% 27% 16% 4	2160
	11th to 20th	Day	33% 6% 10% 24% 25% 2	2123
	21st to end	Day	29% 5% 8% 29% 26% 3	1980
October	1st to 10th	Day	28% 5% 10% 27% 25% 5%	1825
	11th to 20th	Day	35% 4 7% 25% 22% 7%	1800
	21st to end	Day	40% 4 7% 25% 19% 5%	1975
November	1st to 10th	Day	31% 3 12% 26% 21% 7%	1672
	11th to 20th	Day	38% 4 7% 23% 22% 6%	1710
	21st to end	Day	44% 4 8% 24% 19% 2	1710
December	1st to 10th	Day	44% 4 10% 26% 15% 2	1525
	11th to 20th	Day	47% 5% 8% 21% 18% 2	1915
	21st to end	Day	54% 6% 10% 15% 12% 3	2783
January	1st to 10th	Night	43% 5% 9% 23% 17% 2	2648
	11th to 20th	Night	46% 5% 9% 24% 14% 2	2503
	21st to end	Night	44% 4 11% 24% 15% 2	2600
February	1st to 10th	Night	50% 5% 8% 22% 14% 2	2308
	11th to 20th	Night	44% 4 10% 20% 18% 3	2099
	21st to end	Night	46% 5% 8% 22% 15% 4	1776
March	1st to 10th	Night	44% 4 9% 19% 18% 6%	2160
	11th to 20th	Night	48% 5% 11% 20% 14% 3	1980
	21st to end	Night	51% 6% 11% 21% 10% 2	2054
April	1st to 10th	Night	32% 6% 12% 27% 20% 3	1800
	11th to 20th	Night	39% 6% 11% 21% 19% 4	1775
	21st to end	Night	45% 4 8% 24% 16% 3	1800
May	1st to 10th	Night	39% 6% 13% 25% 15% 2	1769
	11th to 20th	Night	41% 7% 13% 19% 18% 2	1515
	21st to end	Night	39% 8% 15% 20% 16% 2	1552
June	1st to 10th	Night	33% 7% 13% 25% 20% 2	1440
	11th to 20th	Night	22% 6% 13% 30% 23% 5%	1440
	21st to end	Night	21% 8% 17% 30% 17% 8%	1440
July	1st to 10th	Night	28% 7% 17% 28% 15% 6%	1400
	11th to 20th	Night	26% 6% 17% 28% 19% 5%	1392
	21st to end	Night	26% 9% 16% 32% 16% 1	1644
August	1st to 10th	Night	27% 9% 19% 29% 15% 2	1656
	11th to 20th	Night	29% 7% 13% 28% 21% 3	1776
	21st to end	Night	26% 7% 15% 27% 19% 5%	1980
September	1st to 10th	Night	31% 7% 8% 30% 18% 6%	1800
	11th to 20th	Night	30% 6% 10% 27% 25% 3	1818
	21st to end	Night	27% 6% 9% 24% 29% 5%	1980
October	1st to 10th	Night	24% 5% 11% 26% 29% 5%	2132
	11th to 20th	Night	32% 4 7% 25% 24% 7%	2160
	21st to end	Night	41% 4 8% 23% 19% 6%	2380
November	1st to 10th	Night	29% 4 11% 27% 24% 6%	2406
	11th to 20th	Night	35% 3 8% 23% 24% 7%	2470
	21st to end	Night	41% 4 7% 25% 21% 2	2470
December	1st to 10th	Night	44% 5% 11% 23% 16% 2	2650
	11th to 20th	Night	43% 5% 10% 24% 18% 2	3281
	21st to end	Night	52% 6% 10% 18% 12% 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	27% 19% 35% 16% 2 1	270
	11th to 20th	Day	27% 23% 37% 11% 1	270
	21st to end	Day	19% 28% 38% 12% 2	267
February	1st to 10th	Day	26% 20% 42% 11% 1	240
	11th to 20th	Day	28% 29% 32% 9% 2	240
	21st to end	Day	33% 22% 34% 9% 3	198
March	1st to 10th	Day	22% 21% 42% 14% 1	240
	11th to 20th	Day	32% 17% 35% 14% 3	240
	21st to end	Day	26% 22% 33% 15% 3	387
April	1st to 10th	Day	17% 23% 35% 19% 5% 1	420
	11th to 20th	Day	24% 18% 29% 20% 8% 1	412
	21st to end	Day	22% 14% 37% 18% 8% 1	420
May	1st to 10th	Day	19% 17% 34% 22% 7% 1	423
	11th to 20th	Day	20% 12% 28% 23% 14% 3	523
	21st to end	Day	10% 6% 33% 29% 16% 6%	679
June	1st to 10th	Day	12% 4 23% 25% 28% 8%	630
	11th to 20th	Day	6% 3 24% 39% 21% 6%	630
	21st to end	Day	4 4 30% 34% 19% 8%	630
July	1st to 10th	Day	9% 2 15% 31% 27% 15%	621
	11th to 20th	Day	6% 2 18% 37% 27% 10%	618
	21st to end	Day	7% 4 18% 35% 28% 8%	684
August	1st to 10th	Day	9% 2 15% 38% 27% 10%	568
	11th to 20th	Day	13% 3 17% 30% 29% 8%	439
	21st to end	Day	9% 2 14% 30% 32% 13%	495
September	1st to 10th	Day	10% 3 16% 34% 27% 9%	450
	11th to 20th	Day	8% 4 16% 31% 30% 12%	450
	21st to end	Day	13% 8% 20% 30% 20% 9%	450
October	1st to 10th	Day	13% 7% 27% 39% 10% 4	295
	11th to 20th	Day	21% 13% 36% 23% 6% 1	270
	21st to end	Day	31% 14% 35% 16% 4	297
November	1st to 10th	Day	16% 13% 38% 23% 9% 2	270
	11th to 20th	Day	19% 20% 33% 20% 7% 1	270
	21st to end	Day	26% 17% 35% 16% 6%	270
December	1st to 10th	Day	19% 19% 36% 17% 7% 2	270
	11th to 20th	Day	29% 15% 36% 17% 3	270
	21st to end	Day	26% 21% 39% 10% 3	297
January	1st to 10th	Night	21% 21% 35% 19% 4	950
	11th to 20th	Night	25% 24% 33% 16% 3	950
	21st to end	Night	20% 18% 40% 20% 2	1000
February	1st to 10th	Night	24% 21% 35% 18% 2	868
	11th to 20th	Night	21% 23% 37% 18% 1	703
	21st to end	Night	24% 20% 35% 19% 2	592
March	1st to 10th	Night	23% 18% 37% 19% 3	720
	11th to 20th	Night	23% 12% 38% 23% 4	540
	21st to end	Night	23% 15% 33% 24% 5%	594
April	1st to 10th	Night	13% 17% 39% 27% 4	540
	11th to 20th	Night	19% 14% 28% 27% 12% 1	533
	21st to end	Night	23% 11% 36% 22% 9%	540
May	1st to 10th	Night	16% 10% 35% 27% 10% 1	540
	11th to 20th	Night	19% 5% 32% 27% 15% 2	531
	21st to end	Night	11% 3 26% 36% 20% 4	584
June	1st to 10th	Night	10% 4 19% 36% 29% 3	540
	11th to 20th	Night	6% 1 21% 46% 24% 1	540
	21st to end	Night	5% 3 22% 40% 29% 1	540
July	1st to 10th	Night	7% 1 12% 35% 37% 8%	525
	11th to 20th	Night	7% 2 12% 39% 34% 7%	522
	21st to end	Night	7% 2 14% 39% 33% 5%	591
August	1st to 10th	Night	7% 1 12% 39% 36% 6%	537
	11th to 20th	Night	9% 2 12% 36% 37% 4	534
	21st to end	Night	7% 2 12% 34% 38% 7%	594
September	1st to 10th	Night	11% 3 15% 31% 34% 6%	540
	11th to 20th	Night	10% 2 15% 32% 36% 6%	558
	21st to end	Night	10% 6% 21% 31% 27% 5%	720
October	1st to 10th	Night	8% 7% 26% 33% 22% 4	720
	11th to 20th	Night	16% 9% 33% 27% 13% 1	720
	21st to end	Night	23% 13% 31% 26% 8%	792
November	1st to 10th	Night	13% 10% 37% 28% 11% 1	740
	11th to 20th	Night	20% 13% 32% 27% 8%	760
	21st to end	Night	23% 13% 33% 24% 7%	760
December	1st to 10th	Night	22% 15% 35% 22% 5% 1	940
	11th to 20th	Night	23% 12% 36% 24% 4	950
	21st to end	Night	25% 17% 37% 18% 3	1045

Page generated at 2024-01-19 08:28:31. Version ac07

Copyright 2024 Attilla Danko