Corner Brook
Clear Sky Chart
History

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

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	18% 16% 6% 12% 6% 5% 4 3 4 5% 20%	101654
	Night	17% 17% 7% 15% 8% 5% 4 3 4 4 16%	97543
Transparency	Day	66% 5% 10% 13% 4	105081
	Night	71% 5% 9% 11% 3	102210
Seeing	Day	30% 20% 27% 15% 6% 1	17984
	Night	29% 18% 24% 21% 7% 1	24981

By Month

Percentage Cloud Cover NE (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	9% 18% 9% 26% 16% 8% 2 2 2 2 5%	2526
	11th to 20th	Day	11% 21% 8% 33% 10% 6% 3 2 1 2 4	2530
	21st to end	Day	7% 14% 10% 26% 13% 8% 4 3 3 2 11%	2783
February	1st to 10th	Day	15% 15% 6% 20% 17% 10% 5% 3 3 2 5%	1528
	11th to 20th	Day	14% 20% 7% 20% 14% 6% 4 3 2 2 7%	1724
	21st to end	Day	9% 16% 8% 19% 14% 10% 5% 3 3 2 11%	1570
March	1st to 10th	Day	10% 21% 5% 13% 9% 8% 4 3 4 4 19%	3114
	11th to 20th	Day	14% 32% 11% 14% 6% 5% 3 2 2 3 7%	3261
	21st to end	Day	20% 18% 9% 15% 6% 4 3 2 3 4 17%	4167
April	1st to 10th	Day	16% 22% 9% 18% 7% 4 3 3 4 4 12%	2280
	11th to 20th	Day	14% 17% 7% 12% 5% 4 4 3 4 6% 24%	2314
	21st to end	Day	19% 19% 6% 11% 6% 4 3 2 4 4 22%	2508
May	1st to 10th	Day	21% 20% 5% 10% 4 4 3 3 4 4 24%	4425
	11th to 20th	Day	15% 15% 4 7% 4 5% 4 4 6% 7% 29%	4398
	21st to end	Day	25% 14% 4 8% 5% 4 3 3 5% 6% 22%	4955
June	1st to 10th	Day	27% 15% 3 8% 6% 4 5% 3 5% 6% 18%	2850
	11th to 20th	Day	19% 10% 3 8% 5% 4 4 4 6% 7% 29%	2850
	21st to end	Day	24% 13% 3 7% 5% 4 4 4 5% 6% 25%	2850
July	1st to 10th	Day	20% 13% 4 9% 6% 5% 5% 4 5% 7% 24%	4605
	11th to 20th	Day	15% 9% 4 10% 7% 6% 6% 5% 6% 7% 26%	4440
	21st to end	Day	17% 8% 2 6% 5% 5% 4 4 5% 8% 35%	4815
August	1st to 10th	Day	20% 8% 3 8% 5% 5% 5% 5% 7% 9% 24%	4424
	11th to 20th	Day	18% 9% 3 7% 4 4 4 3 6% 8% 34%	4238
	21st to end	Day	22% 8% 3 8% 5% 4 4 3 5% 6% 31%	4262
September	1st to 10th	Day	22% 9% 3 8% 5% 4 4 3 6% 7% 30%	2280
	11th to 20th	Day	27% 12% 3 8% 6% 4 4 3 5% 6% 24%	2185
	21st to end	Day	22% 13% 4 9% 5% 4 4 4 6% 7% 22%	2090
October	1st to 10th	Day	22% 14% 3 8% 5% 4 4 3 5% 5% 28%	1974
	11th to 20th	Day	24% 19% 5% 9% 4 4 3 3 4 6% 19%	1778
	21st to end	Day	24% 25% 7% 10% 5% 4 2 2 2 3 17%	1881
November	1st to 10th	Day	22% 29% 9% 11% 5% 3 4 3 3 3 9%	1717
	11th to 20th	Day	19% 28% 9% 12% 5% 4 3 2 3 4 12%	1542
	21st to end	Day	16% 25% 12% 18% 5% 4 4 3 4 4 6%	1346
December	1st to 10th	Day	19% 23% 11% 21% 6% 5% 4 2 3 2 4	1330
	11th to 20th	Day	22% 21% 8% 22% 9% 3 3 2 2 2 4	1668
	21st to end	Day	16% 26% 10% 21% 7% 3 2 2 3 3 7%	2446
January	1st to 10th	Night	10% 18% 10% 24% 18% 8% 3 2 2 2 4	4429
	11th to 20th	Night	12% 17% 7% 31% 10% 6% 5% 3 3 3 5%	4440
	21st to end	Night	6% 12% 11% 26% 13% 7% 7% 3 3 3 9%	4884
February	1st to 10th	Night	12% 17% 6% 23% 17% 10% 5% 2 2 2 4	2651
	11th to 20th	Night	13% 19% 8% 20% 14% 7% 6% 2 2 3 5%	2342
	21st to end	Night	8% 16% 6% 19% 14% 8% 6% 2 3 3 14%	1884
March	1st to 10th	Night	11% 18% 6% 13% 12% 8% 5% 4 4 5% 14%	3726
	11th to 20th	Night	9% 25% 12% 18% 9% 7% 4 3 3 3 8%	3696
	21st to end	Night	17% 19% 9% 16% 6% 4 3 3 3 4 16%	3465
April	1st to 10th	Night	18% 20% 8% 16% 6% 4 4 3 4 5% 13%	1900
	11th to 20th	Night	14% 19% 7% 12% 6% 5% 4 3 4 5% 21%	1816
	21st to end	Night	16% 15% 7% 12% 7% 5% 4 4 6% 5% 20%	1670
May	1st to 10th	Night	21% 20% 6% 9% 5% 4 4 3 5% 6% 19%	2525
	11th to 20th	Night	16% 14% 4 6% 5% 4 5% 4 5% 6% 30%	2506
	21st to end	Night	27% 12% 3 7% 4 4 4 3 5% 6% 24%	2626
June	1st to 10th	Night	26% 15% 5% 9% 6% 4 3 4 4 5% 19%	1330
	11th to 20th	Night	20% 8% 3 6% 4 5% 5% 5% 7% 7% 29%	1330
	21st to end	Night	20% 9% 4 7% 5% 5% 6% 5% 6% 6% 25%	1330
July	1st to 10th	Night	20% 11% 4 10% 6% 5% 4 4 6% 6% 24%	2361
	11th to 20th	Night	15% 12% 4 9% 5% 5% 6% 4 6% 8% 24%	2530
	21st to end	Night	16% 8% 3 6% 4 4 4 4 5% 6% 39%	2750
August	1st to 10th	Night	13% 8% 3 8% 6% 6% 5% 6% 7% 8% 29%	2516
	11th to 20th	Night	18% 7% 2 7% 5% 5% 6% 4 6% 6% 35%	2598
	21st to end	Night	19% 9% 3 7% 4 4 5% 3 5% 6% 34%	3382
September	1st to 10th	Night	23% 9% 3 7% 4 3 5% 4 5% 5% 31%	1900
	11th to 20th	Night	25% 13% 4 9% 4 4 4 3 4 5% 26%	1995
	21st to end	Night	23% 12% 4 8% 5% 4 4 3 5% 6% 26%	2090
October	1st to 10th	Night	22% 14% 3 7% 5% 5% 5% 4 5% 6% 25%	2204
	11th to 20th	Night	23% 19% 4 10% 6% 4 4 3 4 4 19%	2401
	21st to end	Night	24% 22% 5% 10% 5% 4 4 3 4 5% 16%	2717
November	1st to 10th	Night	19% 28% 7% 11% 6% 4 4 3 4 4 10%	2483
	11th to 20th	Night	20% 25% 9% 14% 5% 5% 4 3 3 4 10%	2636
	21st to end	Night	18% 24% 11% 16% 7% 4 3 3 3 4 8%	2831
December	1st to 10th	Night	15% 26% 10% 21% 7% 5% 3 2 3 3 6%	2850
	11th to 20th	Night	21% 23% 10% 21% 9% 4 3 2 1 1 5%	3531
	21st to end	Night	17% 20% 11% 25% 8% 4 3 2 2 2 6%	5218

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	88% 2 4 5% 1	2527
	11th to 20th	Day	90% 3 3 4 1	2530
	21st to end	Day	82% 3 3 5% 4 3	2783
February	1st to 10th	Day	86% 3 4 5% 2	1528
	11th to 20th	Day	86% 2 4 6% 2	1732
	21st to end	Day	81% 4 5% 7% 4	1570
March	1st to 10th	Day	69% 4 8% 10% 9%	3118
	11th to 20th	Day	85% 3 3 6% 2	3261
	21st to end	Day	74% 4 3 14% 4 1	4167
April	1st to 10th	Day	78% 5% 5% 8% 4 1	2280
	11th to 20th	Day	63% 5% 9% 16% 7%	2314
	21st to end	Day	66% 6% 7% 12% 8% 1	2508
May	1st to 10th	Day	63% 7% 9% 16% 5%	4440
	11th to 20th	Day	53% 7% 16% 17% 7% 1	4402
	21st to end	Day	64% 5% 10% 15% 7%	4955
June	1st to 10th	Day	68% 6% 8% 13% 5%	2850
	11th to 20th	Day	53% 7% 14% 21% 5%	2850
	21st to end	Day	60% 6% 11% 15% 7% 1	2850
July	1st to 10th	Day	61% 6% 11% 18% 5%	4534
	11th to 20th	Day	56% 8% 16% 17% 3	4364
	21st to end	Day	47% 7% 21% 21% 3	4662
August	1st to 10th	Day	55% 8% 15% 18% 3	4410
	11th to 20th	Day	48% 6% 16% 20% 8% 2	4280
	21st to end	Day	52% 6% 16% 21% 5%	4262
September	1st to 10th	Day	54% 5% 13% 20% 8%	2280
	11th to 20th	Day	61% 5% 13% 15% 4 1	2185
	21st to end	Day	62% 6% 14% 14% 4	2090
October	1st to 10th	Day	58% 7% 11% 19% 4	3273
	11th to 20th	Day	71% 6% 12% 8% 3	2936
	21st to end	Day	68% 5% 10% 13% 3	3092
November	1st to 10th	Day	82% 4 7% 5% 2	1717
	11th to 20th	Day	78% 4 6% 9% 2	1542
	21st to end	Day	83% 5% 7% 4 1	1346
December	1st to 10th	Day	87% 4 5% 4	1330
	11th to 20th	Day	90% 2 4 2 1	1667
	21st to end	Day	85% 2 7% 5% 1	2446
January	1st to 10th	Night	89% 3 4 3 1	4429
	11th to 20th	Night	86% 4 4 4 1	4440
	21st to end	Night	80% 4 4 5% 5% 3	4884
February	1st to 10th	Night	89% 3 3 3 1	2651
	11th to 20th	Night	86% 4 5% 4 1	2345
	21st to end	Night	76% 3 7% 9% 5%	1884
March	1st to 10th	Night	71% 7% 6% 11% 5%	3735
	11th to 20th	Night	84% 4 4 7% 2	3697
	21st to end	Night	73% 4 6% 12% 5% 1	3465
April	1st to 10th	Night	73% 7% 6% 10% 3 1	1900
	11th to 20th	Night	65% 5% 8% 14% 7%	1816
	21st to end	Night	63% 7% 9% 13% 7%	1670
May	1st to 10th	Night	65% 6% 8% 16% 4 1	2530
	11th to 20th	Night	53% 7% 15% 19% 6%	2507
	21st to end	Night	60% 7% 12% 17% 4	2627
June	1st to 10th	Night	68% 6% 8% 14% 5%	1330
	11th to 20th	Night	51% 7% 17% 19% 6%	1330
	21st to end	Night	57% 7% 14% 15% 6%	1330
July	1st to 10th	Night	60% 5% 14% 15% 6%	2323
	11th to 20th	Night	56% 8% 15% 17% 5%	2482
	21st to end	Night	44% 6% 16% 29% 4	2663
August	1st to 10th	Night	49% 10% 19% 20% 1	2505
	11th to 20th	Night	49% 6% 19% 18% 5% 2	2622
	21st to end	Night	49% 7% 19% 22% 3	3381
September	1st to 10th	Night	55% 6% 14% 19% 6%	1900
	11th to 20th	Night	61% 6% 13% 13% 7%	1995
	21st to end	Night	59% 6% 13% 16% 6%	2090
October	1st to 10th	Night	55% 9% 12% 17% 5% 1	3672
	11th to 20th	Night	70% 5% 12% 10% 2	3989
	21st to end	Night	67% 6% 11% 13% 3 1	4467
November	1st to 10th	Night	78% 5% 9% 7% 1	2483
	11th to 20th	Night	80% 4 8% 7% 2	2636
	21st to end	Night	83% 3 6% 6% 1	2831
December	1st to 10th	Night	86% 4 6% 4	2850
	11th to 20th	Night	90% 2 3 3 1	3533
	21st to end	Night	87% 4 4 5% 1	5218

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	26% 30% 28% 11% 3 2	370
	11th to 20th	Day	30% 25% 28% 13% 4 1	370
	21st to end	Day	27% 27% 26% 16% 5%	407
February	1st to 10th	Day	29% 27% 24% 13% 6% 1	370
	11th to 20th	Day	35% 28% 22% 10% 3 1	366
	21st to end	Day	23% 29% 33% 8% 5% 2	307
March	1st to 10th	Day	23% 29% 31% 12% 3 2	370
	11th to 20th	Day	31% 26% 21% 14% 8% 1	382
	21st to end	Day	34% 26% 24% 10% 4 2	506
April	1st to 10th	Day	34% 29% 24% 11% 2	460
	11th to 20th	Day	28% 25% 27% 13% 5% 1	512
	21st to end	Day	30% 20% 28% 16% 6% 2	650
May	1st to 10th	Day	35% 16% 25% 16% 6% 2	653
	11th to 20th	Day	25% 18% 27% 17% 12% 1	674
	21st to end	Day	32% 21% 25% 15% 5% 1	735
June	1st to 10th	Day	35% 16% 25% 15% 7% 2	680
	11th to 20th	Day	28% 16% 28% 20% 8% 1	680
	21st to end	Day	32% 15% 27% 16% 9% 2	680
July	1st to 10th	Day	26% 14% 31% 19% 8% 2	670
	11th to 20th	Day	22% 16% 34% 19% 9%	668
	21st to end	Day	27% 14% 29% 22% 7% 1	740
August	1st to 10th	Day	23% 14% 30% 23% 8% 1	675
	11th to 20th	Day	25% 14% 28% 21% 9% 2	667
	21st to end	Day	28% 16% 27% 20% 8% 2	595
September	1st to 10th	Day	26% 22% 30% 18% 4	490
	11th to 20th	Day	37% 17% 30% 11% 4	440
	21st to end	Day	32% 21% 29% 13% 4 1	390
October	1st to 10th	Day	29% 22% 30% 11% 6% 2	390
	11th to 20th	Day	37% 17% 22% 13% 8% 2	390
	21st to end	Day	37% 21% 24% 11% 6% 1	429
November	1st to 10th	Day	43% 22% 22% 10% 2 1	381
	11th to 20th	Day	35% 22% 21% 13% 8% 2	370
	21st to end	Day	38% 25% 22% 13% 2	370
December	1st to 10th	Day	36% 23% 23% 13% 5%	370
	11th to 20th	Day	34% 26% 26% 10% 3	370
	21st to end	Day	28% 29% 24% 11% 6% 1	407
January	1st to 10th	Night	30% 26% 23% 17% 4	850
	11th to 20th	Night	27% 28% 28% 13% 4	850
	21st to end	Night	23% 25% 29% 19% 4	935
February	1st to 10th	Night	27% 28% 25% 16% 4 1	846
	11th to 20th	Night	29% 23% 29% 15% 3 1	743
	21st to end	Night	22% 22% 27% 18% 8% 2	628
March	1st to 10th	Night	23% 28% 27% 17% 5% 1	760
	11th to 20th	Night	25% 20% 24% 23% 8% 1	733
	21st to end	Night	29% 18% 26% 20% 7%	627
April	1st to 10th	Night	32% 21% 24% 16% 6% 1	570
	11th to 20th	Night	26% 16% 26% 25% 6% 1	564
	21st to end	Night	26% 15% 25% 27% 6% 1	570
May	1st to 10th	Night	30% 13% 22% 26% 7% 2	570
	11th to 20th	Night	29% 13% 23% 23% 12%	562
	21st to end	Night	33% 11% 25% 23% 7% 1	616
June	1st to 10th	Night	34% 11% 19% 25% 10% 1	570
	11th to 20th	Night	23% 13% 24% 28% 11% 1	570
	21st to end	Night	26% 11% 27% 26% 8% 2	570
July	1st to 10th	Night	25% 10% 28% 24% 12% 1	556
	11th to 20th	Night	23% 10% 27% 32% 9%	552
	21st to end	Night	25% 9% 25% 31% 10%	623
August	1st to 10th	Night	23% 10% 24% 30% 13% 1	568
	11th to 20th	Night	25% 7% 26% 28% 13% 1	562
	21st to end	Night	24% 9% 24% 28% 14% 1	627
September	1st to 10th	Night	29% 16% 23% 25% 6% 1	570
	11th to 20th	Night	35% 12% 23% 24% 6%	570
	21st to end	Night	32% 15% 26% 21% 7%	570
October	1st to 10th	Night	32% 13% 26% 23% 6% 1	684
	11th to 20th	Night	38% 13% 20% 21% 7% 1	825
	21st to end	Night	38% 19% 20% 17% 7%	946
November	1st to 10th	Night	39% 19% 23% 15% 4	859
	11th to 20th	Night	38% 17% 22% 16% 6% 1	850
	21st to end	Night	37% 24% 21% 15% 3	850
December	1st to 10th	Night	31% 23% 24% 16% 6%	850
	11th to 20th	Night	33% 26% 24% 15% 2	850
	21st to end	Night	27% 25% 25% 15% 6% 1	935

Page generated at 2024-11-03 14:19:05. Version ac07

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