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 2024-09-29.

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	8% 7% 3 7% 5% 4 5% 4 6% 8% 44%	101456
	Night	7% 9% 3 8% 5% 5% 5% 4 6% 8% 41%	96873
Transparency	Day	37% 6% 14% 27% 13% 3	101199
	Night	40% 6% 15% 24% 12% 2	96776
Seeing	Day	13% 10% 27% 28% 18% 5%	15343
	Night	12% 10% 33% 31% 12% 1	24457

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% 14% 5% 9% 5% 5% 6% 5% 7% 10% 29%	2219
	11th to 20th	Day	4 8% 5% 11% 7% 7% 9% 6% 6% 5% 31%	2201
	21st to end	Day	3 8% 4 9% 6% 5% 4 4 6% 7% 42%	2794
February	1st to 10th	Day	8% 14% 4 12% 7% 6% 4 4 5% 6% 29%	1632
	11th to 20th	Day	7% 13% 3 10% 6% 7% 6% 6% 7% 8% 28%	1665
	21st to end	Day	4 12% 5% 11% 8% 5% 4 5% 5% 7% 33%	1470
March	1st to 10th	Day	5% 10% 3 9% 6% 6% 6% 4 7% 8% 37%	3220
	11th to 20th	Day	7% 8% 3 6% 4 4 4 4 5% 9% 46%	3489
	21st to end	Day	10% 15% 5% 10% 6% 5% 5% 4 6% 7% 27%	3825
April	1st to 10th	Day	9% 12% 3 9% 5% 5% 7% 5% 6% 7% 32%	2316
	11th to 20th	Day	11% 12% 3 8% 5% 5% 5% 4 6% 8% 33%	2440
	21st to end	Day	11% 9% 3 7% 6% 4 4 5% 6% 8% 36%	2470
May	1st to 10th	Day	21% 11% 4 6% 4 4 4 3 5% 6% 32%	4238
	11th to 20th	Day	9% 5% 2 7% 5% 5% 6% 5% 8% 10% 38%	4596
	21st to end	Day	14% 6% 3 7% 5% 5% 6% 5% 7% 8% 34%	5161
June	1st to 10th	Day	12% 5% 3 6% 5% 5% 4 5% 7% 9% 39%	2850
	11th to 20th	Day	15% 6% 3 6% 5% 5% 5% 5% 7% 9% 33%	2850
	21st to end	Day	7% 4 1 5% 4 4 4 5% 6% 9% 52%	2850
July	1st to 10th	Day	5% 3 1 5% 3 4 4 4 6% 8% 57%	4740
	11th to 20th	Day	4 3 1 3 3 3 3 3 6% 8% 64%	4740
	21st to end	Day	2 2 1 2 2 2 3 3 4 7% 72%	5080
August	1st to 10th	Day	8% 5% 2 4 3 3 4 4 6% 9% 52%	4250
	11th to 20th	Day	5% 3 2 5% 4 4 4 4 6% 8% 56%	4028
	21st to end	Day	8% 3 1 3 3 3 3 3 5% 7% 60%	4521
September	1st to 10th	Day	10% 4 2 4 3 3 3 2 5% 6% 58%	2356
	11th to 20th	Day	14% 6% 2 5% 3 3 3 3 4 8% 49%	2090
	21st to end	Day	10% 6% 1 5% 4 3 4 4 5% 7% 51%	2069
October	1st to 10th	Day	11% 9% 3 7% 4 4 4 3 5% 7% 42%	1852
	11th to 20th	Day	8% 9% 3 8% 4 5% 5% 3 5% 6% 44%	1766
	21st to end	Day	10% 8% 3 6% 5% 4 4 5% 7% 7% 40%	1782
November	1st to 10th	Day	12% 14% 3 7% 5% 5% 4 4 5% 7% 35%	1516
	11th to 20th	Day	6% 9% 3 8% 6% 5% 5% 4 6% 7% 40%	1520
	21st to end	Day	4 11% 5% 11% 5% 5% 4 4 7% 10% 35%	1406
December	1st to 10th	Day	6% 13% 4 8% 8% 5% 6% 3 5% 6% 36%	1330
	11th to 20th	Day	5% 12% 4 9% 7% 6% 5% 4 6% 7% 35%	1682
	21st to end	Day	5% 7% 3 8% 5% 4 5% 3 5% 7% 48%	2442
January	1st to 10th	Night	4 11% 4 10% 6% 5% 5% 4 6% 10% 34%	4726
	11th to 20th	Night	4 9% 5% 11% 5% 5% 6% 5% 6% 8% 35%	4699
	21st to end	Night	4 10% 3 10% 5% 5% 5% 4 5% 7% 43%	4890
February	1st to 10th	Night	8% 13% 4 11% 5% 5% 5% 3 5% 7% 33%	2547
	11th to 20th	Night	6% 13% 4 11% 6% 5% 6% 4 6% 8% 29%	2402
	21st to end	Night	5% 13% 5% 10% 6% 6% 5% 4 5% 8% 34%	1980
March	1st to 10th	Night	4 9% 5% 11% 7% 5% 5% 4 6% 7% 36%	3654
	11th to 20th	Night	7% 7% 3 6% 5% 5% 5% 4 7% 8% 44%	3490
	21st to end	Night	13% 18% 5% 10% 5% 5% 4 4 6% 7% 23%	3828
April	1st to 10th	Night	9% 12% 4 8% 5% 5% 5% 5% 6% 7% 35%	1862
	11th to 20th	Night	10% 10% 3 9% 6% 4 5% 4 7% 8% 34%	1691
	21st to end	Night	10% 10% 3 7% 5% 5% 6% 4 7% 7% 35%	1710
May	1st to 10th	Night	19% 12% 3 7% 5% 5% 5% 4 5% 6% 30%	2732
	11th to 20th	Night	9% 6% 3 7% 5% 6% 5% 4 7% 9% 39%	2296
	21st to end	Night	15% 8% 3 9% 7% 6% 6% 5% 6% 8% 27%	2414
June	1st to 10th	Night	14% 7% 3 8% 4 4 4 4 6% 8% 38%	1330
	11th to 20th	Night	14% 6% 2 6% 5% 6% 4 5% 7% 8% 36%	1330
	21st to end	Night	6% 3 1 5% 4 4 5% 5% 7% 9% 51%	1330
July	1st to 10th	Night	3 2 1 4 4 5% 6% 4 7% 9% 55%	2220
	11th to 20th	Night	5% 4 1 3 3 3 4 3 5% 10% 58%	2220
	21st to end	Night	3 2 1 4 3 3 3 4 5% 8% 64%	2469
August	1st to 10th	Night	8% 4 2 5% 4 4 4 4 5% 8% 53%	2683
	11th to 20th	Night	4 3 1 5% 4 5% 6% 5% 8% 11% 47%	2811
	21st to end	Night	8% 4 1 4 3 3 3 3 5% 7% 59%	3146
September	1st to 10th	Night	10% 5% 2 5% 3 4 3 4 5% 7% 53%	1822
	11th to 20th	Night	12% 6% 1 5% 4 4 3 3 6% 7% 50%	2090
	21st to end	Night	7% 7% 2 5% 3 4 4 4 6% 7% 51%	2079
October	1st to 10th	Night	12% 6% 2 5% 4 4 4 4 5% 7% 46%	2107
	11th to 20th	Night	9% 8% 3 7% 4 4 4 4 5% 8% 45%	2191
	21st to end	Night	8% 7% 3 8% 5% 5% 5% 4 7% 8% 39%	2574
November	1st to 10th	Night	11% 12% 3 7% 6% 5% 4 4 5% 7% 36%	2544
	11th to 20th	Night	6% 10% 3 8% 5% 5% 5% 4 7% 7% 41%	2660
	21st to end	Night	5% 12% 4 8% 5% 5% 4 4 6% 8% 41%	2772
December	1st to 10th	Night	5% 13% 4 9% 6% 5% 5% 4 6% 7% 36%	2850
	11th to 20th	Night	4 9% 4 10% 5% 5% 5% 5% 7% 9% 36%	3510
	21st to end	Night	5% 9% 3 6% 4 4 5% 4 6% 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	1632
	11th to 20th	Day	52% 7% 14% 19% 8% 1	1674
	21st to end	Day	49% 6% 14% 19% 10% 2	1470
March	1st to 10th	Day	40% 8% 13% 27% 11%	3220
	11th to 20th	Day	34% 7% 23% 26% 10% 1	3490
	21st to end	Day	55% 9% 14% 17% 5%	3825
April	1st to 10th	Day	48% 7% 12% 23% 8% 1	2316
	11th to 20th	Day	49% 5% 10% 25% 9% 2	2440
	21st to end	Day	45% 6% 14% 24% 10% 1	2470
May	1st to 10th	Day	53% 4 10% 25% 6%	4238
	11th to 20th	Day	36% 7% 16% 31% 10% 1	4600
	21st to end	Day	43% 8% 14% 24% 9% 1	5162
June	1st to 10th	Day	40% 6% 18% 22% 12% 2	2850
	11th to 20th	Day	44% 6% 14% 22% 12% 2	2850
	21st to end	Day	27% 6% 17% 33% 13% 3	2850
July	1st to 10th	Day	23% 5% 15% 30% 21% 6%	4666
	11th to 20th	Day	19% 4 15% 34% 21% 7%	4659
	21st to end	Day	13% 3 9% 30% 27% 18%	4919
August	1st to 10th	Day	27% 5% 12% 35% 19% 2	4233
	11th to 20th	Day	25% 5% 16% 39% 13% 2	4067
	21st to end	Day	23% 4 12% 41% 18% 3	4520
September	1st to 10th	Day	28% 3 13% 28% 19% 9%	2356
	11th to 20th	Day	35% 4 13% 30% 14% 4	2090
	21st to end	Day	32% 5% 13% 31% 15% 4	2069
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	51% 5% 13% 18% 11% 1	2547
	11th to 20th	Night	51% 6% 15% 18% 10% 1	2403
	21st to end	Night	48% 5% 16% 20% 9% 2	1980
March	1st to 10th	Night	45% 7% 14% 25% 9%	3654
	11th to 20th	Night	35% 7% 21% 26% 11% 1	3490
	21st to end	Night	59% 7% 14% 15% 3 1	3828
April	1st to 10th	Night	45% 7% 15% 23% 10%	1862
	11th to 20th	Night	44% 7% 12% 24% 13% 1	1691
	21st to end	Night	45% 6% 14% 25% 9% 1	1710
May	1st to 10th	Night	54% 5% 11% 23% 7% 1	2732
	11th to 20th	Night	35% 9% 15% 29% 12% 1	2296
	21st to end	Night	49% 11% 13% 20% 6% 1	2414
June	1st to 10th	Night	42% 7% 13% 26% 11% 2	1330
	11th to 20th	Night	42% 6% 15% 23% 11% 2	1330
	21st to end	Night	27% 5% 16% 32% 15% 4	1330
July	1st to 10th	Night	21% 7% 18% 27% 22% 4	2185
	11th to 20th	Night	22% 5% 13% 32% 19% 9%	2178
	21st to end	Night	18% 3 8% 28% 27% 16%	2391
August	1st to 10th	Night	30% 5% 11% 31% 18% 6%	2675
	11th to 20th	Night	28% 7% 17% 27% 17% 3	2838
	21st to end	Night	25% 4 11% 36% 20% 4	3146
September	1st to 10th	Night	30% 5% 10% 27% 20% 8%	1822
	11th to 20th	Night	32% 5% 12% 28% 16% 6%	2090
	21st to end	Night	32% 4 12% 32% 17% 3	2079
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	21% 12% 32% 24% 9% 3	234
	11th to 20th	Day	13% 13% 36% 27% 8% 3	270
	21st to end	Day	11% 16% 29% 30% 13% 1	282
March	1st to 10th	Day	12% 16% 35% 23% 12% 3	460
	11th to 20th	Day	11% 13% 30% 27% 14% 5%	460
	21st to end	Day	14% 12% 34% 24% 12% 3	506
April	1st to 10th	Day	15% 18% 31% 25% 10% 1	460
	11th to 20th	Day	14% 13% 29% 29% 13% 1	452
	21st to end	Day	17% 12% 25% 29% 14% 3	460
May	1st to 10th	Day	15% 8% 27% 22% 21% 7%	539
	11th to 20th	Day	16% 6% 21% 30% 21% 6%	675
	21st to end	Day	19% 6% 19% 24% 24% 7%	734
June	1st to 10th	Day	14% 9% 24% 29% 19% 5%	680
	11th to 20th	Day	17% 11% 28% 26% 15% 2	680
	21st to end	Day	9% 6% 22% 33% 24% 7%	680
July	1st to 10th	Day	7% 2 21% 34% 28% 8%	671
	11th to 20th	Day	7% 4 25% 37% 22% 5%	668
	21st to end	Day	4 6% 20% 37% 25% 9%	705
August	1st to 10th	Day	7% 3 20% 32% 28% 9%	487
	11th to 20th	Day	6% 3 20% 30% 30% 11%	477
	21st to end	Day	10% 7% 24% 24% 27% 9%	539
September	1st to 10th	Day	11% 9% 26% 27% 22% 4	490
	11th to 20th	Day	13% 10% 26% 29% 17% 6%	490
	21st to end	Day	15% 11% 30% 27% 11% 5%	483
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	16% 11% 33% 28% 12% 2	760
	11th to 20th	Night	12% 11% 37% 28% 10% 1	744
	21st to end	Night	12% 11% 31% 30% 15% 2	628
March	1st to 10th	Night	9% 12% 35% 31% 12% 2	760
	11th to 20th	Night	11% 12% 35% 29% 10% 2	760
	21st to end	Night	14% 12% 33% 29% 11% 1	836
April	1st to 10th	Night	14% 11% 38% 25% 11% 1	656
	11th to 20th	Night	18% 6% 35% 32% 9%	563
	21st to end	Night	15% 9% 32% 34% 10% 1	570
May	1st to 10th	Night	13% 8% 28% 32% 18% 1	570
	11th to 20th	Night	12% 5% 27% 38% 17% 1	432
	21st to end	Night	22% 7% 21% 30% 18% 1	411
June	1st to 10th	Night	16% 10% 28% 30% 16% 1	380
	11th to 20th	Night	16% 9% 33% 27% 14%	380
	21st to end	Night	7% 5% 29% 41% 15% 2	380
July	1st to 10th	Night	6% 4 21% 48% 21%	370
	11th to 20th	Night	9% 3 27% 43% 18%	368
	21st to end	Night	4 4 22% 46% 23% 2	416
August	1st to 10th	Night	8% 2 21% 46% 21% 2	467
	11th to 20th	Night	8% 3 22% 43% 23% 1	564
	21st to end	Night	8% 5% 27% 40% 20% 1	627
September	1st to 10th	Night	11% 6% 27% 41% 14% 2	592
	11th to 20th	Night	14% 5% 25% 36% 19% 1	760
	21st to end	Night	10% 9% 32% 34% 13% 2	756
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 2024-09-26 07:52:22. Version ac07

Copyright © 2024 Attilla Danko.