Lake Manitoba Narrows
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Manitoba Narrows clear sky chart from 2005-11-06 to 2024-12-02.

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	11% 8% 3 8% 5% 5% 5% 4 6% 8% 38%	105863
	Night	10% 9% 4 9% 6% 5% 5% 4 6% 8% 35%	102388
Transparency	Day	42% 8% 17% 25% 7% 1	105608
	Night	45% 8% 15% 23% 9% 1	102291
Seeing	Day	14% 5% 24% 31% 20% 6%	16381
	Night	15% 5% 26% 35% 16% 2	26361

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% 16% 5% 11% 7% 7% 9% 6% 7% 8% 18%	2219
	11th to 20th	Day	5% 9% 7% 18% 10% 9% 8% 5% 8% 6% 14%	2231
	21st to end	Day	6% 14% 5% 12% 8% 7% 7% 4 6% 7% 25%	2794
February	1st to 10th	Day	8% 10% 5% 12% 9% 6% 7% 7% 7% 7% 22%	1520
	11th to 20th	Day	7% 11% 3 9% 6% 6% 8% 6% 7% 7% 31%	1661
	21st to end	Day	7% 9% 3 10% 8% 7% 6% 6% 6% 8% 31%	1536
March	1st to 10th	Day	10% 9% 3 9% 7% 7% 6% 4 5% 8% 30%	3130
	11th to 20th	Day	8% 9% 3 9% 7% 6% 5% 5% 7% 8% 33%	3446
	21st to end	Day	7% 7% 3 9% 5% 6% 5% 4 6% 8% 40%	3863
April	1st to 10th	Day	8% 9% 3 7% 5% 4 5% 4 6% 7% 41%	2338
	11th to 20th	Day	11% 10% 3 7% 5% 5% 5% 4 6% 6% 38%	2442
	21st to end	Day	12% 7% 2 7% 5% 4 5% 5% 6% 7% 41%	2470
May	1st to 10th	Day	16% 8% 2 6% 4 3 4 4 6% 7% 40%	4346
	11th to 20th	Day	18% 7% 2 6% 5% 4 4 4 5% 6% 39%	4705
	21st to end	Day	17% 7% 2 6% 4 4 5% 4 5% 7% 40%	5173
June	1st to 10th	Day	15% 8% 2 7% 4 4 4 4 5% 8% 40%	2850
	11th to 20th	Day	14% 6% 2 6% 5% 5% 4 4 6% 6% 39%	2850
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 4 7% 8% 40%	2850
July	1st to 10th	Day	10% 5% 2 5% 4 5% 4 4 7% 9% 46%	4750
	11th to 20th	Day	8% 3 1 4 3 4 5% 4 6% 9% 53%	4750
	21st to end	Day	6% 3 1 4 4 4 4 4 7% 9% 53%	5057
August	1st to 10th	Day	8% 4 2 5% 4 5% 6% 5% 7% 9% 45%	4412
	11th to 20th	Day	11% 5% 2 5% 3 4 4 3 6% 9% 48%	4075
	21st to end	Day	13% 5% 2 6% 4 4 4 3 6% 9% 45%	4532
September	1st to 10th	Day	11% 6% 2 6% 4 4 4 4 6% 8% 46%	2361
	11th to 20th	Day	16% 6% 2 6% 5% 4 4 4 6% 8% 39%	2090
	21st to end	Day	13% 8% 2 6% 4 4 5% 4 6% 7% 40%	2090
October	1st to 10th	Day	14% 7% 3 7% 4 4 4 4 5% 7% 41%	3298
	11th to 20th	Day	10% 10% 2 7% 4 4 5% 3 5% 9% 39%	2912
	21st to end	Day	13% 13% 4 9% 5% 5% 6% 4 6% 6% 29%	3091
November	1st to 10th	Day	19% 15% 5% 10% 6% 3 4 2 5% 6% 25%	1629
	11th to 20th	Day	11% 14% 6% 15% 7% 5% 4 4 5% 6% 23%	1534
	21st to end	Day	11% 17% 4 12% 6% 4 5% 3 5% 5% 26%	1400
December	1st to 10th	Day	6% 12% 8% 14% 7% 7% 7% 5% 6% 6% 22%	1337
	11th to 20th	Day	9% 15% 4 14% 8% 5% 5% 4 6% 7% 22%	1679
	21st to end	Day	6% 9% 3 11% 7% 6% 5% 4 6% 7% 37%	2442
January	1st to 10th	Night	5% 13% 5% 11% 7% 8% 8% 5% 6% 8% 24%	4737
	11th to 20th	Night	5% 11% 6% 18% 12% 9% 9% 5% 6% 6% 15%	4677
	21st to end	Night	8% 12% 6% 14% 7% 6% 6% 5% 7% 7% 23%	4873
February	1st to 10th	Night	8% 12% 5% 10% 7% 6% 6% 4 7% 7% 28%	2660
	11th to 20th	Night	4 9% 4 8% 6% 6% 7% 6% 7% 8% 34%	2405
	21st to end	Night	6% 10% 4 10% 7% 7% 5% 5% 5% 7% 35%	1933
March	1st to 10th	Night	10% 12% 3 9% 6% 5% 5% 4 6% 9% 31%	3734
	11th to 20th	Night	6% 7% 3 6% 6% 5% 4 4 7% 7% 43%	3513
	21st to end	Night	7% 10% 3 8% 6% 5% 5% 4 7% 7% 38%	3769
April	1st to 10th	Night	7% 9% 3 7% 6% 5% 4 4 6% 8% 40%	1842
	11th to 20th	Night	14% 9% 4 8% 6% 5% 4 4 5% 7% 34%	1689
	21st to end	Night	11% 8% 3 8% 6% 4 5% 4 6% 7% 37%	1710
May	1st to 10th	Night	17% 9% 3 7% 5% 5% 5% 4 6% 7% 33%	2622
	11th to 20th	Night	16% 8% 3 8% 5% 4 4 4 5% 6% 38%	2201
	21st to end	Night	15% 5% 2 6% 5% 4 4 4 6% 8% 41%	2414
June	1st to 10th	Night	15% 7% 3 7% 5% 5% 4 4 7% 8% 36%	1330
	11th to 20th	Night	15% 5% 2 7% 5% 3 3 4 7% 11% 38%	1330
	21st to end	Night	13% 5% 1 5% 5% 4 5% 6% 8% 9% 38%	1330
July	1st to 10th	Night	8% 3 1 5% 4 4 4 4 7% 10% 50%	2220
	11th to 20th	Night	7% 3 1 4 3 3 4 3 7% 10% 53%	2220
	21st to end	Night	6% 3 2 5% 3 4 4 4 6% 9% 53%	2504
August	1st to 10th	Night	11% 4 2 5% 4 5% 5% 4 7% 8% 44%	2528
	11th to 20th	Night	8% 4 2 4 3 4 4 4 7% 10% 50%	2764
	21st to end	Night	12% 4 2 6% 4 4 4 3 5% 8% 48%	3135
September	1st to 10th	Night	12% 4 1 5% 4 3 3 4 6% 9% 49%	1815
	11th to 20th	Night	13% 7% 2 6% 4 4 4 4 5% 8% 43%	2090
	21st to end	Night	14% 6% 3 7% 4 4 4 4 5% 8% 41%	2090
October	1st to 10th	Night	15% 8% 2 5% 2 3 3 3 5% 8% 46%	3630
	11th to 20th	Night	9% 9% 3 7% 5% 5% 5% 4 6% 9% 39%	4001
	21st to end	Night	10% 11% 3 8% 6% 5% 4 4 6% 7% 36%	4467
November	1st to 10th	Night	15% 14% 4 11% 7% 6% 4 4 5% 5% 25%	2669
	11th to 20th	Night	9% 18% 6% 15% 8% 4 4 3 5% 4 24%	2865
	21st to end	Night	11% 15% 6% 13% 7% 5% 5% 4 5% 7% 23%	3000
December	1st to 10th	Night	8% 12% 6% 12% 8% 6% 7% 4 6% 8% 25%	2878
	11th to 20th	Night	8% 14% 6% 14% 7% 6% 5% 4 6% 6% 23%	3518
	21st to end	Night	7% 9% 4 10% 7% 5% 5% 4 6% 7% 37%	5225

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	59% 10% 15% 13% 2	2219
	11th to 20th	Day	62% 10% 12% 13% 3	2252
	21st to end	Day	54% 9% 13% 19% 5%	2794
February	1st to 10th	Day	56% 9% 15% 13% 7% 1	1520
	11th to 20th	Day	47% 8% 16% 20% 8%	1670
	21st to end	Day	49% 7% 12% 23% 10%	1536
March	1st to 10th	Day	47% 10% 15% 22% 5%	3130
	11th to 20th	Day	41% 14% 16% 20% 8%	3448
	21st to end	Day	38% 10% 17% 26% 9%	3863
April	1st to 10th	Day	40% 7% 15% 25% 13% 1	2338
	11th to 20th	Day	45% 6% 13% 22% 14% 1	2442
	21st to end	Day	40% 8% 16% 26% 8% 2	2470
May	1st to 10th	Day	40% 8% 13% 28% 10% 1	4346
	11th to 20th	Day	43% 9% 12% 23% 10% 2	4709
	21st to end	Day	40% 10% 15% 25% 9%	5173
June	1st to 10th	Day	42% 8% 17% 24% 9% 1	2850
	11th to 20th	Day	42% 8% 17% 21% 10% 1	2850
	21st to end	Day	39% 11% 19% 24% 6%	2850
July	1st to 10th	Day	32% 8% 27% 26% 7%	4676
	11th to 20th	Day	27% 7% 23% 38% 5%	4669
	21st to end	Day	26% 8% 25% 32% 9% 1	4898
August	1st to 10th	Day	32% 8% 20% 32% 8%	4396
	11th to 20th	Day	32% 7% 24% 33% 4	4114
	21st to end	Day	35% 7% 24% 28% 5%	4531
September	1st to 10th	Day	34% 8% 19% 29% 9% 1	2361
	11th to 20th	Day	42% 9% 19% 24% 5%	2090
	21st to end	Day	41% 9% 17% 24% 8%	2090
October	1st to 10th	Day	42% 6% 15% 31% 5%	3298
	11th to 20th	Day	41% 7% 13% 31% 7%	2912
	21st to end	Day	53% 7% 16% 19% 5%	3091
November	1st to 10th	Day	61% 7% 12% 16% 4 1	1629
	11th to 20th	Day	59% 11% 13% 12% 4	1534
	21st to end	Day	59% 6% 15% 16% 3	1400
December	1st to 10th	Day	59% 9% 15% 12% 5%	1337
	11th to 20th	Day	59% 7% 15% 14% 4	1680
	21st to end	Day	44% 8% 14% 17% 15% 1	2442
January	1st to 10th	Night	54% 10% 13% 18% 5%	4737
	11th to 20th	Night	66% 8% 10% 12% 3	4718
	21st to end	Night	55% 10% 14% 17% 5%	4873
February	1st to 10th	Night	52% 6% 14% 19% 8%	2660
	11th to 20th	Night	43% 9% 16% 22% 10%	2406
	21st to end	Night	46% 7% 12% 25% 10%	1933
March	1st to 10th	Night	47% 8% 15% 23% 6% 1	3734
	11th to 20th	Night	34% 10% 16% 25% 15% 1	3513
	21st to end	Night	41% 9% 13% 28% 9% 1	3769
April	1st to 10th	Night	39% 6% 12% 22% 17% 2	1842
	11th to 20th	Night	48% 5% 9% 20% 14% 3	1689
	21st to end	Night	43% 8% 12% 24% 11% 3	1710
May	1st to 10th	Night	45% 10% 13% 22% 10%	2622
	11th to 20th	Night	43% 8% 13% 23% 12% 1	2201
	21st to end	Night	38% 10% 16% 25% 11% 1	2414
June	1st to 10th	Night	42% 9% 15% 23% 10% 1	1330
	11th to 20th	Night	38% 9% 16% 22% 12% 2	1330
	21st to end	Night	37% 13% 19% 24% 6% 1	1330
July	1st to 10th	Night	28% 8% 27% 29% 8%	2185
	11th to 20th	Night	24% 8% 22% 38% 7% 1	2178
	21st to end	Night	27% 7% 21% 31% 13% 1	2425
August	1st to 10th	Night	35% 9% 17% 27% 12%	2520
	11th to 20th	Night	28% 7% 24% 34% 8% 1	2791
	21st to end	Night	34% 6% 20% 33% 7%	3135
September	1st to 10th	Night	31% 6% 19% 29% 14% 1	1815
	11th to 20th	Night	38% 8% 17% 27% 9% 1	2090
	21st to end	Night	40% 6% 14% 29% 9% 1	2090
October	1st to 10th	Night	37% 5% 13% 28% 15% 1	3630
	11th to 20th	Night	41% 6% 12% 29% 10% 1	4001
	21st to end	Night	45% 8% 16% 27% 4	4467
November	1st to 10th	Night	60% 8% 13% 13% 5% 1	2669
	11th to 20th	Night	63% 7% 13% 12% 4 1	2865
	21st to end	Night	59% 9% 14% 14% 4	3000
December	1st to 10th	Night	56% 9% 16% 14% 6%	2878
	11th to 20th	Night	57% 8% 14% 13% 8%	3516
	21st to end	Night	44% 8% 12% 20% 14% 1	5225

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	11% 3 28% 44% 11% 4	270
	11th to 20th	Day	11% 4 27% 40% 15% 3	270
	21st to end	Day	16% 3 24% 35% 19% 4	297
February	1st to 10th	Day	12% 5% 29% 37% 13% 3	270
	11th to 20th	Day	12% 5% 28% 34% 14% 7%	270
	21st to end	Day	6% 4 27% 33% 26% 4	225
March	1st to 10th	Day	15% 4 23% 34% 19% 4	270
	11th to 20th	Day	13% 5% 29% 31% 18% 4	270
	21st to end	Day	13% 4 23% 33% 21% 5%	321
April	1st to 10th	Day	13% 5% 25% 34% 18% 4	518
	11th to 20th	Day	18% 5% 25% 31% 18% 2	640
	21st to end	Day	15% 4 24% 36% 19% 3	650
May	1st to 10th	Day	15% 6% 22% 35% 20% 3	653
	11th to 20th	Day	17% 5% 25% 28% 19% 5%	675
	21st to end	Day	19% 6% 20% 28% 22% 5%	734
June	1st to 10th	Day	17% 6% 25% 26% 18% 8%	680
	11th to 20th	Day	15% 5% 27% 29% 17% 6%	680
	21st to end	Day	11% 5% 18% 33% 28% 6%	680
July	1st to 10th	Day	9% 6% 18% 32% 25% 9%	671
	11th to 20th	Day	11% 4 22% 32% 22% 9%	668
	21st to end	Day	8% 4 23% 28% 26% 11%	739
August	1st to 10th	Day	9% 5% 20% 32% 25% 10%	676
	11th to 20th	Day	12% 5% 18% 26% 25% 14%	665
	21st to end	Day	15% 6% 20% 30% 23% 5%	748
September	1st to 10th	Day	12% 5% 26% 34% 20% 3	571
	11th to 20th	Day	20% 5% 23% 31% 18% 5%	300
	21st to end	Day	16% 7% 27% 33% 13% 4	300
October	1st to 10th	Day	23% 6% 23% 28% 16% 5%	300
	11th to 20th	Day	20% 7% 33% 25% 12% 3	300
	21st to end	Day	22% 8% 29% 28% 11% 3	330
November	1st to 10th	Day	26% 6% 24% 30% 13% 1	300
	11th to 20th	Day	16% 6% 34% 32% 9% 3	300
	21st to end	Day	18% 6% 29% 35% 9% 2	300
December	1st to 10th	Day	11% 8% 28% 31% 18% 4	273
	11th to 20th	Day	15% 9% 30% 30% 13% 2	270
	21st to end	Day	12% 3 24% 35% 22% 4	297
January	1st to 10th	Night	12% 4 32% 37% 14% 1	950
	11th to 20th	Night	15% 5% 29% 37% 14% 1	950
	21st to end	Night	16% 6% 30% 34% 12% 1	1045
February	1st to 10th	Night	15% 4 27% 39% 13% 2	950
	11th to 20th	Night	10% 4 30% 35% 19% 2	929
	21st to end	Night	9% 4 25% 40% 19% 3	677
March	1st to 10th	Night	15% 5% 25% 34% 19% 3	760
	11th to 20th	Night	12% 4 28% 39% 15% 1	590
	21st to end	Night	16% 4 25% 35% 16% 4	627
April	1st to 10th	Night	10% 4 28% 40% 16% 2	570
	11th to 20th	Night	18% 4 25% 37% 16%	563
	21st to end	Night	14% 4 27% 39% 14% 1	570
May	1st to 10th	Night	18% 4 24% 37% 15% 1	570
	11th to 20th	Night	16% 4 25% 35% 18% 2	561
	21st to end	Night	21% 5% 17% 38% 19% 1	617
June	1st to 10th	Night	18% 4 24% 29% 22% 3	570
	11th to 20th	Night	17% 4 23% 34% 19% 2	570
	21st to end	Night	14% 4 18% 38% 25% 2	570
July	1st to 10th	Night	8% 3 20% 40% 26% 4	555
	11th to 20th	Night	10% 3 21% 39% 24% 3	552
	21st to end	Night	9% 3 20% 36% 27% 5%	624
August	1st to 10th	Night	11% 4 19% 38% 25% 3	567
	11th to 20th	Night	13% 3 18% 33% 28% 5%	564
	21st to end	Night	17% 3 20% 37% 21% 3	627
September	1st to 10th	Night	13% 4 22% 39% 19% 2	570
	11th to 20th	Night	15% 6% 23% 38% 17% 1	570
	21st to end	Night	16% 5% 29% 34% 16%	570
October	1st to 10th	Night	23% 7% 29% 30% 10% 1	655
	11th to 20th	Night	23% 6% 25% 31% 14% 1	893
	21st to end	Night	21% 9% 28% 32% 8% 2	1045
November	1st to 10th	Night	22% 7% 30% 28% 12% 2	975
	11th to 20th	Night	18% 9% 31% 30% 9% 3	1000
	21st to end	Night	18% 8% 35% 30% 8% 1	1000
December	1st to 10th	Night	13% 5% 28% 37% 14% 3	960
	11th to 20th	Night	15% 6% 33% 32% 13% 1	950
	21st to end	Night	17% 4 28% 34% 15% 3	1045

Page generated at 2024-11-29 09:43:06. Version ac07

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