Taber
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Taber clear sky chart from 2005-11-06 to 2024-02-05.

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	9% 7% 3 6% 6% 3 5% 5% 6% 8% 43%	77709
	Night	7% 8% 4 7% 6% 3 5% 5% 6% 8% 41%	81105
Transparency	Day	39% 6% 15% 26% 12% 2	77413
	Night	40% 6% 16% 24% 12% 2	80981
Seeing	Day	13% 10% 27% 28% 18% 5%	14332
	Night	12% 10% 34% 30% 12% 1	23748

By Month

Percentage Cloud Cover NW (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	5% 13% 5% 7% 6% 3 6% 7% 7% 10% 29%	2219
	11th to 20th	Day	5% 7% 6% 10% 9% 4 10% 8% 5% 5% 31%	2201
	21st to end	Day	3 8% 5% 8% 8% 4 5% 5% 6% 8% 43%	2794
February	1st to 10th	Day	8% 13% 5% 11% 7% 5% 6% 5% 5% 7% 30%	1578
	11th to 20th	Day	7% 12% 4 8% 8% 6% 6% 7% 7% 8% 27%	1575
	21st to end	Day	5% 10% 7% 10% 9% 4 5% 5% 5% 8% 33%	1386
March	1st to 10th	Day	6% 11% 5% 10% 7% 4 6% 4 6% 7% 33%	1843
	11th to 20th	Day	7% 10% 4 8% 6% 3 6% 4 6% 9% 37%	1979
	21st to end	Day	7% 12% 4 6% 8% 3 6% 6% 7% 8% 33%	2178
April	1st to 10th	Day	9% 10% 4 9% 6% 4 7% 6% 6% 8% 32%	2193
	11th to 20th	Day	11% 11% 4 7% 7% 3 5% 5% 6% 8% 33%	2310
	21st to end	Day	12% 9% 3 5% 7% 3 5% 6% 6% 8% 36%	2340
May	1st to 10th	Day	13% 8% 3 6% 6% 4 5% 5% 6% 9% 36%	2412
	11th to 20th	Day	11% 5% 3 6% 6% 3 5% 5% 7% 9% 42%	2595
	21st to end	Day	21% 7% 3 5% 5% 3 4 4 5% 7% 35%	2917
June	1st to 10th	Day	13% 5% 3 5% 6% 3 5% 5% 6% 9% 39%	2700
	11th to 20th	Day	16% 6% 3 5% 6% 3 6% 7% 7% 9% 34%	2700
	21st to end	Day	7% 3 1 4 4 3 5% 5% 6% 9% 53%	2700
July	1st to 10th	Day	5% 3 2 4 4 3 5% 5% 7% 9% 55%	2700
	11th to 20th	Day	6% 3 1 4 4 2 5% 5% 7% 8% 55%	2700
	21st to end	Day	4 2 1 3 3 2 3 4 4 8% 65%	2906
August	1st to 10th	Day	7% 3 1 3 4 2 3 4 5% 8% 59%	2421
	11th to 20th	Day	7% 4 2 4 3 3 4 4 5% 9% 56%	2299
	21st to end	Day	9% 3 2 3 4 2 3 5% 5% 8% 58%	2574
September	1st to 10th	Day	11% 4 2 4 3 2 3 3 5% 6% 57%	2233
	11th to 20th	Day	14% 5% 2 4 4 2 4 4 4 8% 51%	1980
	21st to end	Day	10% 6% 1 4 5% 3 4 4 5% 7% 50%	1980
October	1st to 10th	Day	11% 9% 3 6% 5% 3 5% 4 5% 7% 42%	1852
	11th to 20th	Day	9% 8% 3 7% 5% 4 5% 4 5% 6% 44%	1766
	21st to end	Day	10% 8% 3 5% 6% 3 5% 6% 7% 7% 40%	1782
November	1st to 10th	Day	12% 13% 3 6% 6% 3 5% 5% 4 8% 35%	1516
	11th to 20th	Day	7% 9% 4 7% 7% 3 5% 5% 6% 7% 40%	1520
	21st to end	Day	5% 9% 5% 10% 5% 4 5% 4 6% 10% 35%	1406
December	1st to 10th	Day	6% 12% 5% 8% 8% 4 6% 4 5% 6% 36%	1330
	11th to 20th	Day	5% 12% 4 8% 8% 5% 7% 5% 5% 7% 35%	1682
	21st to end	Day	5% 7% 4 7% 6% 2 5% 5% 5% 7% 48%	2442
January	1st to 10th	Night	5% 11% 4 9% 8% 4 5% 5% 6% 10% 34%	4726
	11th to 20th	Night	4 8% 6% 10% 7% 4 6% 6% 5% 8% 35%	4699
	21st to end	Night	4 9% 4 9% 6% 4 5% 5% 5% 7% 43%	4890
February	1st to 10th	Night	8% 11% 5% 10% 7% 4 6% 4 5% 7% 33%	2475
	11th to 20th	Night	7% 13% 5% 9% 7% 4 7% 6% 6% 8% 29%	2272
	21st to end	Night	6% 12% 7% 9% 7% 4 5% 5% 5% 7% 33%	1867
March	1st to 10th	Night	5% 9% 5% 9% 7% 3 6% 5% 7% 8% 35%	2117
	11th to 20th	Night	7% 9% 5% 8% 6% 4 6% 5% 6% 9% 34%	1980
	21st to end	Night	7% 12% 4 7% 5% 4 6% 7% 7% 9% 32%	2178
April	1st to 10th	Night	8% 11% 4 7% 6% 3 5% 6% 6% 8% 35%	1765
	11th to 20th	Night	11% 10% 3 7% 7% 3 5% 6% 7% 8% 33%	1601
	21st to end	Night	11% 9% 3 6% 6% 3 6% 5% 7% 8% 36%	1620
May	1st to 10th	Night	10% 8% 4 7% 6% 4 6% 6% 5% 8% 36%	1548
	11th to 20th	Night	10% 5% 3 4 5% 4 5% 4 5% 8% 47%	1294
	21st to end	Night	19% 5% 2 5% 6% 4 8% 4 6% 8% 33%	1358
June	1st to 10th	Night	14% 6% 3 6% 5% 2 4 5% 5% 8% 40%	1260
	11th to 20th	Night	15% 5% 3 5% 5% 4 5% 5% 7% 9% 36%	1260
	21st to end	Night	6% 3 1 4 5% 3 5% 5% 6% 9% 51%	1260
July	1st to 10th	Night	5% 2 1 3 4 4 6% 5% 6% 9% 55%	1260
	11th to 20th	Night	7% 4 1 3 4 2 4 5% 6% 9% 54%	1260
	21st to end	Night	3 2 1 2 4 2 3 5% 5% 8% 64%	1408
August	1st to 10th	Night	6% 4 2 4 4 3 4 6% 5% 8% 54%	1516
	11th to 20th	Night	6% 4 1 3 3 2 4 5% 6% 10% 54%	1602
	21st to end	Night	7% 5% 1 4 4 2 3 4 5% 8% 56%	1782
September	1st to 10th	Night	10% 5% 2 4 4 3 3 4 4 7% 52%	1725
	11th to 20th	Night	11% 5% 2 4 4 3 3 4 5% 7% 51%	1980
	21st to end	Night	7% 7% 3 5% 4 3 4 4 6% 7% 50%	1980
October	1st to 10th	Night	12% 6% 2 4 5% 3 4 4 5% 8% 46%	2107
	11th to 20th	Night	10% 7% 3 6% 5% 3 4 4 5% 8% 45%	2191
	21st to end	Night	8% 7% 3 7% 6% 3 5% 6% 7% 9% 40%	2574
November	1st to 10th	Night	11% 12% 4 6% 6% 3 4 5% 5% 8% 36%	2544
	11th to 20th	Night	6% 9% 3 7% 6% 4 5% 5% 6% 8% 41%	2660
	21st to end	Night	5% 10% 4 7% 5% 3 4 5% 6% 8% 41%	2772
December	1st to 10th	Night	5% 12% 5% 8% 7% 4 5% 5% 6% 7% 36%	2850
	11th to 20th	Night	4 8% 4 9% 7% 4 6% 6% 7% 9% 36%	3510
	21st to end	Night	5% 9% 3 6% 5% 3 5% 5% 5% 8% 47%	5214

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	47% 8% 17% 22% 5% 1	2219
	11th to 20th	Day	53% 7% 11% 13% 15% 2	2222
	21st to end	Day	39% 6% 20% 31% 5% 1	2794
February	1st to 10th	Day	54% 5% 15% 18% 7% 1	1578
	11th to 20th	Day	53% 7% 14% 18% 7% 1	1584
	21st to end	Day	49% 6% 14% 19% 10% 2	1386
March	1st to 10th	Day	49% 6% 15% 22% 8%	1843
	11th to 20th	Day	43% 6% 16% 25% 9% 1	1980
	21st to end	Day	47% 9% 15% 21% 8%	2178
April	1st to 10th	Day	48% 7% 12% 23% 8% 1	2193
	11th to 20th	Day	49% 5% 10% 25% 9% 2	2310
	21st to end	Day	46% 5% 15% 23% 10% 1	2340
May	1st to 10th	Day	45% 5% 15% 23% 11%	2412
	11th to 20th	Day	37% 5% 15% 29% 13% 1	2599
	21st to end	Day	48% 5% 13% 23% 10% 1	2918
June	1st to 10th	Day	40% 5% 18% 22% 11% 2	2700
	11th to 20th	Day	44% 6% 15% 21% 12% 2	2700
	21st to end	Day	27% 6% 18% 33% 13% 3	2700
July	1st to 10th	Day	24% 6% 16% 33% 16% 5%	2626
	11th to 20th	Day	25% 6% 15% 29% 21% 4	2619
	21st to end	Day	18% 5% 13% 32% 26% 6%	2744
August	1st to 10th	Day	23% 5% 15% 33% 20% 4	2404
	11th to 20th	Day	25% 6% 16% 35% 15% 3	2299
	21st to end	Day	24% 5% 14% 31% 22% 5%	2574
September	1st to 10th	Day	29% 3 13% 29% 18% 9%	2233
	11th to 20th	Day	33% 4 12% 31% 15% 4	1980
	21st to end	Day	33% 5% 13% 31% 14% 3	1980
October	1st to 10th	Day	40% 6% 16% 26% 11% 2	1852
	11th to 20th	Day	41% 6% 14% 27% 10% 2	1766
	21st to end	Day	40% 7% 16% 25% 11% 1	1782
November	1st to 10th	Day	49% 6% 14% 22% 8% 2	1516
	11th to 20th	Day	43% 5% 19% 24% 9% 1	1520
	21st to end	Day	43% 6% 18% 23% 9% 2	1406
December	1st to 10th	Day	48% 7% 15% 20% 8% 3	1330
	11th to 20th	Day	47% 5% 18% 26% 4 1	1684
	21st to end	Day	35% 5% 17% 25% 17% 1	2442
January	1st to 10th	Night	44% 7% 19% 24% 6% 1	4726
	11th to 20th	Night	47% 6% 14% 17% 14% 2	4740
	21st to end	Night	40% 6% 19% 27% 8%	4890
February	1st to 10th	Night	50% 5% 14% 18% 11% 2	2475
	11th to 20th	Night	51% 6% 15% 18% 9%	2273
	21st to end	Night	49% 5% 15% 19% 10% 2	1867
March	1st to 10th	Night	44% 7% 17% 24% 8% 1	2117
	11th to 20th	Night	45% 6% 17% 21% 10% 1	1980
	21st to end	Night	46% 9% 17% 21% 6% 1	2178
April	1st to 10th	Night	45% 7% 15% 23% 10%	1765
	11th to 20th	Night	45% 7% 12% 23% 13% 1	1601
	21st to end	Night	44% 6% 14% 25% 9% 1	1620
May	1st to 10th	Night	44% 6% 12% 26% 11% 1	1548
	11th to 20th	Night	33% 5% 14% 29% 17% 2	1294
	21st to end	Night	48% 6% 13% 22% 9% 1	1358
June	1st to 10th	Night	41% 6% 13% 27% 11% 2	1260
	11th to 20th	Night	41% 6% 16% 24% 11% 1	1260
	21st to end	Night	27% 6% 16% 32% 16% 3	1260
July	1st to 10th	Night	22% 8% 16% 31% 18% 4	1225
	11th to 20th	Night	26% 7% 16% 22% 21% 8%	1218
	21st to end	Night	18% 4 13% 28% 28% 10%	1330
August	1st to 10th	Night	29% 5% 13% 28% 20% 5%	1508
	11th to 20th	Night	25% 5% 14% 27% 23% 5%	1602
	21st to end	Night	27% 4 11% 25% 26% 7%	1782
September	1st to 10th	Night	31% 5% 10% 27% 19% 7%	1725
	11th to 20th	Night	31% 5% 12% 29% 17% 6%	1980
	21st to end	Night	32% 4 12% 32% 16% 3	1980
October	1st to 10th	Night	35% 5% 17% 26% 14% 2	2107
	11th to 20th	Night	37% 5% 15% 26% 13% 3	2191
	21st to end	Night	40% 7% 15% 26% 11% 1	2574
November	1st to 10th	Night	47% 6% 14% 22% 9% 2	2544
	11th to 20th	Night	40% 6% 19% 22% 12%	2660
	21st to end	Night	41% 5% 21% 21% 10% 2	2772
December	1st to 10th	Night	46% 6% 15% 21% 10% 1	2850
	11th to 20th	Night	41% 8% 25% 21% 4 1	3507
	21st to end	Night	36% 5% 14% 26% 17% 3	5214

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	12% 14% 33% 21% 12% 9%	180
	11th to 20th	Day	9% 12% 33% 29% 14% 2	180
	21st to end	Day	10% 18% 34% 27% 8% 3	198
February	1st to 10th	Day	19% 14% 33% 23% 7% 4	216
	11th to 20th	Day	15% 15% 39% 22% 7% 3	240
	21st to end	Day	11% 13% 30% 30% 13% 2	252
March	1st to 10th	Day	12% 16% 34% 23% 12% 3	420
	11th to 20th	Day	11% 14% 30% 26% 14% 5%	420
	21st to end	Day	13% 13% 34% 24% 13% 3	462
April	1st to 10th	Day	13% 18% 31% 26% 10% 1	420
	11th to 20th	Day	15% 13% 29% 30% 14% 1	412
	21st to end	Day	17% 12% 24% 30% 15% 3	420
May	1st to 10th	Day	15% 6% 28% 22% 22% 8%	495
	11th to 20th	Day	16% 6% 21% 29% 22% 6%	625
	21st to end	Day	20% 6% 19% 24% 23% 8%	679
June	1st to 10th	Day	14% 8% 23% 30% 20% 5%	630
	11th to 20th	Day	17% 10% 29% 26% 16% 2	630
	21st to end	Day	8% 4 21% 34% 25% 7%	630
July	1st to 10th	Day	7% 2 21% 33% 29% 8%	621
	11th to 20th	Day	8% 4 26% 37% 21% 4	618
	21st to end	Day	4 5% 20% 37% 26% 9%	652
August	1st to 10th	Day	7% 4 20% 32% 28% 9%	447
	11th to 20th	Day	7% 3 20% 29% 29% 12%	437
	21st to end	Day	10% 5% 24% 24% 27% 9%	495
September	1st to 10th	Day	12% 10% 26% 27% 21% 3	450
	11th to 20th	Day	12% 9% 26% 30% 17% 6%	450
	21st to end	Day	15% 11% 30% 27% 12% 6%	450
October	1st to 10th	Day	16% 8% 24% 28% 18% 6%	322
	11th to 20th	Day	13% 15% 31% 24% 13% 4	270
	21st to end	Day	20% 14% 34% 20% 9% 3	297
November	1st to 10th	Day	25% 14% 30% 20% 9% 1	270
	11th to 20th	Day	13% 17% 40% 22% 7% 1	270
	21st to end	Day	9% 19% 38% 19% 10% 6%	216
December	1st to 10th	Day	12% 18% 38% 23% 8% 1	180
	11th to 20th	Day	16% 17% 39% 18% 9% 1	180
	21st to end	Day	17% 10% 32% 26% 11% 5%	198
January	1st to 10th	Night	11% 16% 40% 24% 8% 1	950
	11th to 20th	Night	12% 15% 36% 28% 9% 1	950
	21st to end	Night	12% 17% 39% 23% 7% 2	851
February	1st to 10th	Night	15% 11% 33% 27% 12% 2	738
	11th to 20th	Night	13% 12% 38% 27% 10% 1	704
	21st to end	Night	12% 10% 30% 30% 16% 2	592
March	1st to 10th	Night	10% 11% 35% 31% 11% 2	720
	11th to 20th	Night	12% 12% 36% 29% 10% 2	720
	21st to end	Night	13% 12% 33% 29% 11% 1	792
April	1st to 10th	Night	13% 10% 38% 26% 11% 1	622
	11th to 20th	Night	18% 6% 35% 32% 9%	533
	21st to end	Night	15% 9% 31% 34% 10% 1	540
May	1st to 10th	Night	12% 8% 28% 32% 19% 1	540
	11th to 20th	Night	12% 5% 26% 38% 17% 1	409
	21st to end	Night	22% 7% 21% 30% 18% 2	389
June	1st to 10th	Night	15% 10% 28% 30% 16% 1	360
	11th to 20th	Night	17% 9% 34% 27% 14%	360
	21st to end	Night	7% 5% 29% 41% 16% 2	360
July	1st to 10th	Night	6% 4 21% 47% 21%	350
	11th to 20th	Night	10% 3 28% 42% 17%	348
	21st to end	Night	4 3 22% 46% 23% 2	394
August	1st to 10th	Night	8% 2 21% 47% 21% 2	442
	11th to 20th	Night	8% 3 22% 43% 23% 1	534
	21st to end	Night	7% 5% 27% 40% 21% 1	594
September	1st to 10th	Night	12% 6% 28% 40% 13% 2	560
	11th to 20th	Night	14% 4 25% 36% 19% 1	720
	21st to end	Night	11% 8% 32% 33% 14% 2	720
October	1st to 10th	Night	15% 7% 26% 35% 16% 1	720
	11th to 20th	Night	14% 9% 36% 28% 11% 2	720
	21st to end	Night	11% 16% 37% 27% 9%	792
November	1st to 10th	Night	18% 13% 40% 24% 6%	879
	11th to 20th	Night	12% 16% 44% 22% 6% 1	950
	21st to end	Night	11% 13% 43% 26% 7% 1	950
December	1st to 10th	Night	13% 12% 36% 27% 10% 2	950
	11th to 20th	Night	9% 15% 40% 26% 8% 1	950
	21st to end	Night	13% 13% 38% 27% 8% 2	1045

Page generated at 2024-02-02 03:20:32. Version ac07

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