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 2024-01-16.

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	20% 15% 6% 11% 8% 4 4 4 4 5% 19%	74558
	Night	18% 16% 7% 13% 9% 4 5% 4 4 4 16%	75245
Transparency	Day	68% 5% 9% 12% 4	74260
	Night	73% 5% 9% 10% 3	75078
Seeing	Day	30% 20% 27% 15% 6% 1	16789
	Night	29% 18% 24% 21% 7% 1	23949

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	15% 17% 10% 23% 16% 4 4 3 2 2 5%	1516
	11th to 20th	Day	12% 19% 10% 22% 16% 6% 4 3 2 2 4	1480
	21st to end	Day	11% 15% 10% 22% 21% 7% 4 3 2 1 4	1584
February	1st to 10th	Day	15% 12% 7% 17% 21% 9% 5% 4 3 2 5%	1448
	11th to 20th	Day	14% 18% 9% 17% 16% 5% 4 4 2 2 7%	1631
	21st to end	Day	10% 15% 9% 18% 15% 8% 7% 4 3 2 11%	1480
March	1st to 10th	Day	12% 19% 8% 14% 12% 5% 6% 3 4 4 14%	1796
	11th to 20th	Day	13% 21% 8% 13% 9% 5% 6% 4 3 5% 13%	1845
	21st to end	Day	16% 19% 10% 11% 10% 4 5% 3 3 3 17%	2376
April	1st to 10th	Day	17% 19% 10% 16% 9% 3 3 3 4 4 12%	2160
	11th to 20th	Day	15% 16% 7% 11% 6% 3 4 4 4 7% 23%	2190
	21st to end	Day	19% 18% 6% 9% 7% 3 4 3 4 4 22%	2376
May	1st to 10th	Day	22% 18% 5% 8% 6% 3 3 4 4 4 24%	2520
	11th to 20th	Day	20% 15% 4 7% 5% 3 4 4 4 5% 31%	2478
	21st to end	Day	24% 14% 4 7% 6% 3 5% 4 5% 7% 23%	2791
June	1st to 10th	Day	27% 13% 4 7% 6% 4 5% 4 5% 7% 19%	2700
	11th to 20th	Day	20% 9% 3 7% 6% 3 4 4 6% 7% 30%	2700
	21st to end	Day	24% 12% 4 6% 5% 3 4 4 5% 6% 25%	2700
July	1st to 10th	Day	19% 10% 4 6% 6% 4 6% 6% 5% 8% 26%	2620
	11th to 20th	Day	17% 9% 4 8% 7% 3 5% 5% 6% 7% 30%	2520
	21st to end	Day	21% 10% 4 7% 7% 4 5% 5% 5% 7% 26%	2745
August	1st to 10th	Day	19% 7% 3 8% 6% 4 5% 6% 7% 8% 26%	2506
	11th to 20th	Day	23% 9% 4 6% 6% 3 5% 4 6% 7% 26%	2416
	21st to end	Day	25% 7% 3 6% 6% 3 4 4 5% 7% 28%	2430
September	1st to 10th	Day	23% 8% 3 6% 6% 3 4 3 6% 7% 30%	2160
	11th to 20th	Day	28% 12% 3 7% 6% 3 4 3 4 6% 23%	2070
	21st to end	Day	22% 13% 5% 8% 6% 3 4 5% 5% 7% 22%	1980
October	1st to 10th	Day	23% 13% 3 6% 6% 3 4 4 5% 5% 29%	1871
	11th to 20th	Day	24% 18% 6% 7% 5% 3 3 4 4 6% 19%	1685
	21st to end	Day	24% 24% 7% 9% 6% 3 3 2 3 3 16%	1782
November	1st to 10th	Day	22% 29% 9% 10% 6% 2 4 3 3 3 9%	1670
	11th to 20th	Day	19% 26% 10% 11% 5% 3 3 3 3 5% 12%	1542
	21st to end	Day	16% 24% 12% 16% 7% 3 4 3 4 4 7%	1346
December	1st to 10th	Day	19% 21% 12% 20% 7% 4 4 3 3 3 4	1330
	11th to 20th	Day	23% 19% 10% 19% 12% 3 3 3 2 2 4	1668
	21st to end	Day	17% 25% 11% 20% 9% 3 2 2 3 3 7%	2446
January	1st to 10th	Night	15% 20% 11% 18% 17% 5% 4 3 2 2 3	2649
	11th to 20th	Night	13% 16% 10% 20% 14% 7% 6% 4 3 3 5%	2591
	21st to end	Night	11% 15% 9% 20% 20% 7% 4 3 3 3 5%	2772
February	1st to 10th	Night	12% 15% 7% 18% 23% 8% 7% 3 2 2 4	2511
	11th to 20th	Night	13% 17% 10% 18% 15% 6% 7% 3 3 3 6%	2215
	21st to end	Night	9% 15% 7% 16% 17% 6% 7% 3 2 3 14%	1776
March	1st to 10th	Night	12% 17% 9% 14% 13% 6% 6% 4 3 4 12%	2151
	11th to 20th	Night	12% 15% 8% 13% 11% 7% 6% 4 5% 5% 14%	2112
	21st to end	Night	17% 18% 8% 13% 9% 3 4 4 3 3 17%	1980
April	1st to 10th	Night	19% 18% 8% 14% 8% 3 4 4 4 5% 14%	1800
	11th to 20th	Night	14% 18% 9% 11% 7% 4 4 4 4 5% 21%	1720
	21st to end	Night	16% 14% 7% 11% 8% 3 5% 4 6% 5% 21%	1583
May	1st to 10th	Night	21% 15% 5% 7% 6% 3 5% 4 4 6% 23%	1440
	11th to 20th	Night	21% 14% 4 6% 4 3 4 4 4 6% 30%	1416
	21st to end	Night	25% 11% 3 6% 4 3 5% 4 5% 7% 26%	1479
June	1st to 10th	Night	25% 13% 5% 8% 7% 4 3 5% 3 6% 20%	1260
	11th to 20th	Night	20% 8% 3 5% 5% 3 5% 6% 7% 8% 29%	1260
	21st to end	Night	20% 9% 5% 7% 6% 4 6% 6% 5% 7% 25%	1260
July	1st to 10th	Night	21% 8% 3 7% 5% 3 5% 4 6% 9% 29%	1336
	11th to 20th	Night	16% 10% 4 7% 6% 3 5% 4 5% 8% 31%	1440
	21st to end	Night	22% 9% 4 7% 7% 3 5% 5% 5% 6% 26%	1573
August	1st to 10th	Night	17% 10% 4 7% 7% 3 6% 6% 7% 9% 26%	1433
	11th to 20th	Night	19% 8% 3 7% 5% 3 6% 5% 6% 7% 30%	1483
	21st to end	Night	20% 9% 3 5% 6% 3 5% 5% 6% 7% 30%	1925
September	1st to 10th	Night	24% 9% 3 6% 5% 3 5% 4 5% 6% 30%	1800
	11th to 20th	Night	26% 12% 4 7% 5% 3 3 4 4 6% 26%	1890
	21st to end	Night	24% 11% 4 7% 6% 3 4 4 5% 6% 26%	1980
October	1st to 10th	Night	22% 14% 3 6% 6% 3 5% 5% 4 6% 25%	2088
	11th to 20th	Night	24% 18% 5% 8% 7% 3 4 4 4 4 20%	2274
	21st to end	Night	25% 22% 5% 8% 6% 3 3 4 4 5% 16%	2574
November	1st to 10th	Night	20% 26% 7% 10% 7% 3 4 3 4 4 11%	2408
	11th to 20th	Night	20% 22% 10% 13% 6% 4 4 4 3 4 10%	2636
	21st to end	Night	18% 23% 12% 15% 8% 3 4 3 3 4 8%	2831
December	1st to 10th	Night	16% 23% 12% 19% 8% 4 4 3 3 3 6%	2850
	11th to 20th	Night	21% 21% 12% 19% 12% 3 3 2 2 1 5%	3531
	21st to end	Night	17% 19% 12% 23% 9% 3 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	89% 2 3 4 1	1517
	11th to 20th	Day	90% 3 3 4 1	1480
	21st to end	Day	90% 3 3 3 1	1584
February	1st to 10th	Day	87% 3 4 4 2	1448
	11th to 20th	Day	85% 2 4 6% 2	1639
	21st to end	Day	81% 3 5% 7% 4	1480
March	1st to 10th	Day	76% 5% 6% 9% 3 1	1800
	11th to 20th	Day	77% 4 5% 11% 3	1845
	21st to end	Day	74% 3 5% 11% 6% 1	2376
April	1st to 10th	Day	78% 4 6% 8% 3 1	2160
	11th to 20th	Day	64% 4 8% 16% 8%	2190
	21st to end	Day	67% 6% 7% 12% 7% 1	2376
May	1st to 10th	Day	64% 5% 8% 15% 8%	2520
	11th to 20th	Day	57% 6% 10% 16% 9% 1	2482
	21st to end	Day	63% 5% 11% 15% 6%	2791
June	1st to 10th	Day	67% 6% 8% 14% 5%	2700
	11th to 20th	Day	54% 7% 14% 21% 5%	2700
	21st to end	Day	60% 7% 11% 15% 7% 1	2700
July	1st to 10th	Day	55% 8% 14% 19% 4	2549
	11th to 20th	Day	54% 6% 13% 21% 5%	2444
	21st to end	Day	58% 7% 14% 17% 4	2592
August	1st to 10th	Day	53% 8% 16% 19% 4	2492
	11th to 20th	Day	57% 8% 14% 15% 5%	2416
	21st to end	Day	57% 6% 16% 17% 5%	2430
September	1st to 10th	Day	54% 5% 13% 19% 8%	2160
	11th to 20th	Day	63% 5% 12% 15% 4 1	2070
	21st to end	Day	62% 6% 14% 14% 5%	1980
October	1st to 10th	Day	58% 6% 12% 18% 6% 1	1871
	11th to 20th	Day	67% 6% 12% 12% 4	1685
	21st to end	Day	75% 4 7% 10% 3 1	1782
November	1st to 10th	Day	82% 4 7% 5% 2	1670
	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	90% 2 4 3 1	2649
	11th to 20th	Night	87% 4 4 4 1	2591
	21st to end	Night	87% 2 5% 4 1	2772
February	1st to 10th	Night	90% 3 3 3 1	2511
	11th to 20th	Night	86% 4 5% 4 1	2218
	21st to end	Night	76% 3 6% 9% 5%	1776
March	1st to 10th	Night	77% 5% 5% 9% 3	2160
	11th to 20th	Night	72% 5% 6% 13% 3 1	2113
	21st to end	Night	71% 5% 8% 9% 6% 1	1980
April	1st to 10th	Night	74% 6% 6% 11% 3 1	1800
	11th to 20th	Night	66% 5% 8% 14% 7%	1720
	21st to end	Night	63% 8% 10% 13% 6%	1583
May	1st to 10th	Night	61% 7% 9% 15% 6% 1	1440
	11th to 20th	Night	57% 5% 11% 17% 9%	1417
	21st to end	Night	57% 7% 11% 19% 6%	1480
June	1st to 10th	Night	67% 6% 8% 14% 5%	1260
	11th to 20th	Night	51% 7% 16% 19% 6%	1260
	21st to end	Night	58% 7% 14% 15% 6%	1260
July	1st to 10th	Night	53% 6% 17% 18% 5%	1298
	11th to 20th	Night	53% 6% 13% 22% 6%	1392
	21st to end	Night	58% 5% 14% 20% 3	1486
August	1st to 10th	Night	52% 8% 20% 18% 2	1422
	11th to 20th	Night	54% 6% 17% 17% 5% 1	1483
	21st to end	Night	51% 7% 18% 19% 4	1925
September	1st to 10th	Night	55% 6% 14% 19% 5%	1800
	11th to 20th	Night	61% 6% 13% 13% 7%	1890
	21st to end	Night	60% 6% 13% 16% 6%	1980
October	1st to 10th	Night	59% 7% 12% 13% 8% 1	2088
	11th to 20th	Night	69% 5% 12% 12% 3	2274
	21st to end	Night	72% 5% 8% 10% 4 1	2574
November	1st to 10th	Night	78% 5% 9% 7% 1	2408
	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% 24% 29% 13% 4 1	355
	21st to end	Day	28% 27% 26% 16% 4	374
February	1st to 10th	Day	31% 28% 24% 13% 4	340
	11th to 20th	Day	34% 29% 21% 11% 4 1	336
	21st to end	Day	22% 29% 34% 8% 6% 2	280
March	1st to 10th	Day	22% 29% 31% 12% 3 2	340
	11th to 20th	Day	29% 27% 22% 14% 7% 1	350
	21st to end	Day	31% 27% 24% 11% 5% 2	462
April	1st to 10th	Day	35% 30% 23% 10% 2	420
	11th to 20th	Day	28% 25% 27% 14% 6% 1	468
	21st to end	Day	29% 20% 27% 16% 6% 2	600
May	1st to 10th	Day	36% 17% 23% 15% 7% 2	603
	11th to 20th	Day	26% 19% 27% 16% 11% 1	624
	21st to end	Day	32% 21% 25% 16% 5% 1	680
June	1st to 10th	Day	34% 15% 26% 16% 7% 2	630
	11th to 20th	Day	27% 15% 27% 21% 9% 1	630
	21st to end	Day	31% 15% 27% 16% 9% 2	630
July	1st to 10th	Day	26% 14% 30% 20% 8% 2	620
	11th to 20th	Day	22% 15% 34% 19% 10%	618
	21st to end	Day	28% 13% 28% 22% 8% 1	685
August	1st to 10th	Day	23% 13% 30% 24% 9% 2	625
	11th to 20th	Day	26% 14% 28% 20% 9% 2	617
	21st to end	Day	28% 15% 27% 21% 8% 2	549
September	1st to 10th	Day	26% 20% 30% 18% 5%	450
	11th to 20th	Day	39% 17% 28% 11% 4	405
	21st to end	Day	33% 22% 29% 12% 4 1	360
October	1st to 10th	Day	29% 23% 30% 11% 6% 2	360
	11th to 20th	Day	36% 18% 22% 14% 9% 2	360
	21st to end	Day	36% 20% 24% 12% 6% 1	396
November	1st to 10th	Day	44% 22% 21% 10% 2 1	365
	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% 27% 28% 13% 4	826
	21st to end	Night	24% 24% 28% 19% 4	880
February	1st to 10th	Night	27% 30% 25% 16% 2	796
	11th to 20th	Night	29% 23% 28% 15% 3 1	703
	21st to end	Night	22% 21% 27% 19% 9% 2	592
March	1st to 10th	Night	21% 29% 27% 17% 5% 1	720
	11th to 20th	Night	24% 19% 25% 23% 8% 1	695
	21st to end	Night	28% 18% 26% 20% 7%	594
April	1st to 10th	Night	33% 21% 23% 17% 6% 1	540
	11th to 20th	Night	25% 15% 27% 26% 6% 1	534
	21st to end	Night	25% 16% 25% 27% 6% 1	540
May	1st to 10th	Night	30% 13% 23% 26% 7% 2	540
	11th to 20th	Night	30% 12% 23% 22% 13%	532
	21st to end	Night	32% 11% 25% 23% 7% 1	583
June	1st to 10th	Night	33% 11% 19% 26% 10% 1	540
	11th to 20th	Night	23% 12% 24% 29% 11% 1	540
	21st to end	Night	26% 10% 27% 26% 9% 2	540
July	1st to 10th	Night	25% 10% 28% 24% 12% 1	526
	11th to 20th	Night	23% 9% 26% 31% 10%	522
	21st to end	Night	26% 8% 25% 31% 10%	590
August	1st to 10th	Night	24% 9% 23% 30% 14% 1	538
	11th to 20th	Night	25% 7% 25% 29% 13% 1	532
	21st to end	Night	24% 9% 24% 28% 14% 1	594
September	1st to 10th	Night	30% 15% 22% 25% 7% 1	540
	11th to 20th	Night	35% 11% 23% 25% 6%	540
	21st to end	Night	33% 15% 26% 19% 6%	540
October	1st to 10th	Night	32% 13% 26% 23% 5% 1	648
	11th to 20th	Night	37% 14% 20% 21% 8% 1	778
	21st to end	Night	38% 19% 19% 17% 7%	891
November	1st to 10th	Night	39% 19% 22% 16% 4	830
	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 2024-01-13 02:38:12. Version ac07

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