Fort Providence
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Providence clear sky chart from 2005-11-06 to 2024-01-14.

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	10% 9% 4 8% 7% 4 6% 6% 6% 8% 32%	74374
	Night	8% 12% 5% 10% 8% 4 6% 6% 6% 7% 27%	75385
Transparency	Day	48% 8% 17% 21% 6%	74007
	Night	54% 8% 15% 18% 5%	75270
Seeing	Day	14% 7% 23% 31% 20% 6%	16037
	Night	14% 5% 22% 34% 22% 4	23893

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	6% 14% 7% 14% 13% 4 6% 4 5% 10% 16%	759
	11th to 20th	Day	7% 17% 6% 12% 10% 5% 8% 6% 6% 6% 17%	998
	21st to end	Day	7% 15% 7% 13% 10% 4 6% 6% 6% 7% 20%	1188
February	1st to 10th	Day	3 7% 5% 10% 10% 6% 7% 7% 8% 10% 28%	1246
	11th to 20th	Day	6% 12% 7% 13% 9% 4 6% 6% 6% 9% 23%	1400
	21st to end	Day	4 9% 6% 12% 8% 6% 7% 7% 8% 8% 25%	1242
March	1st to 10th	Day	4 10% 6% 10% 8% 4 5% 6% 8% 8% 30%	1800
	11th to 20th	Day	7% 13% 5% 10% 7% 4 5% 5% 6% 8% 29%	1831
	21st to end	Day	5% 10% 4 7% 6% 4 6% 7% 6% 8% 37%	2376
April	1st to 10th	Day	8% 11% 4 9% 8% 4 5% 4 4 6% 36%	2227
	11th to 20th	Day	6% 8% 3 6% 6% 3 5% 5% 5% 7% 43%	2447
	21st to end	Day	5% 9% 5% 9% 8% 5% 6% 6% 6% 8% 32%	2596
May	1st to 10th	Day	9% 8% 4 6% 6% 4 5% 5% 6% 8% 40%	2790
	11th to 20th	Day	11% 7% 3 6% 5% 3 5% 5% 6% 7% 40%	2867
	21st to end	Day	11% 6% 2 4 4 3 5% 5% 6% 9% 45%	3324
June	1st to 10th	Day	12% 7% 3 7% 6% 4 5% 6% 7% 9% 34%	3240
	11th to 20th	Day	11% 6% 3 7% 6% 4 7% 7% 6% 10% 32%	3240
	21st to end	Day	9% 6% 3 5% 6% 4 6% 7% 8% 11% 37%	3240
July	1st to 10th	Day	12% 6% 3 7% 7% 4 6% 6% 7% 9% 33%	3240
	11th to 20th	Day	8% 6% 3 6% 6% 5% 6% 7% 7% 10% 35%	3178
	21st to end	Day	9% 6% 2 5% 6% 3 6% 6% 8% 9% 39%	3135
August	1st to 10th	Day	11% 6% 3 6% 6% 4 6% 6% 5% 8% 40%	2865
	11th to 20th	Day	16% 8% 3 6% 6% 4 5% 6% 6% 8% 33%	2523
	21st to end	Day	15% 8% 3 7% 6% 4 6% 6% 5% 7% 33%	2753
September	1st to 10th	Day	16% 8% 3 6% 6% 3 5% 5% 7% 8% 34%	2260
	11th to 20th	Day	15% 10% 3 6% 4 3 5% 5% 6% 8% 35%	2121
	21st to end	Day	14% 10% 4 7% 7% 4 6% 6% 6% 8% 29%	1972
October	1st to 10th	Day	9% 15% 5% 9% 7% 5% 5% 6% 5% 7% 26%	1742
	11th to 20th	Day	13% 16% 6% 9% 6% 4 5% 5% 4 6% 26%	1620
	21st to end	Day	12% 19% 7% 10% 8% 3 4 4 5% 5% 22%	1522
November	1st to 10th	Day	14% 16% 6% 10% 10% 5% 5% 5% 5% 5% 20%	1302
	11th to 20th	Day	10% 20% 8% 11% 8% 3 6% 5% 4 5% 20%	1132
	21st to end	Day	10% 16% 8% 10% 10% 6% 8% 5% 4 5% 19%	950
December	1st to 10th	Day	9% 15% 8% 11% 10% 7% 6% 5% 6% 6% 18%	903
	11th to 20th	Day	7% 10% 5% 13% 12% 6% 6% 6% 6% 11% 17%	959
	21st to end	Day	8% 12% 4 10% 9% 4 9% 6% 8% 6% 25%	1386
January	1st to 10th	Night	8% 15% 7% 14% 10% 5% 6% 6% 6% 6% 18%	3406
	11th to 20th	Night	9% 13% 7% 13% 9% 5% 8% 7% 6% 7% 16%	3034
	21st to end	Night	7% 16% 7% 12% 9% 4 7% 6% 4 6% 22%	3168
February	1st to 10th	Night	4 7% 5% 12% 9% 4 7% 8% 8% 10% 27%	2730
	11th to 20th	Night	6% 13% 7% 11% 9% 4 6% 7% 5% 7% 25%	2446
	21st to end	Night	5% 12% 5% 12% 9% 6% 7% 7% 7% 7% 25%	2013
March	1st to 10th	Night	3 9% 6% 10% 7% 5% 6% 5% 6% 7% 37%	2160
	11th to 20th	Night	5% 13% 6% 10% 8% 4 6% 5% 6% 7% 32%	2128
	21st to end	Night	5% 9% 5% 8% 7% 4 5% 6% 6% 9% 37%	1980
April	1st to 10th	Night	7% 14% 4 9% 8% 4 5% 5% 5% 6% 33%	1732
	11th to 20th	Night	6% 8% 4 5% 6% 4 5% 6% 6% 7% 43%	1460
	21st to end	Night	6% 8% 5% 7% 9% 5% 7% 7% 5% 7% 34%	1364
May	1st to 10th	Night	6% 6% 4 7% 6% 4 6% 7% 8% 9% 37%	1170
	11th to 20th	Night	9% 6% 4 7% 6% 4 6% 6% 6% 9% 38%	1027
	21st to end	Night	12% 6% 3 5% 4 3 3 6% 6% 8% 44%	948
June	1st to 10th	Night	10% 7% 4 8% 7% 4 6% 6% 6% 7% 36%	720
	11th to 20th	Night	9% 6% 4 6% 7% 3 4 7% 9% 9% 36%	720
	21st to end	Night	8% 4 3 7% 6% 4 6% 8% 6% 9% 39%	720
July	1st to 10th	Night	9% 5% 3 6% 8% 5% 5% 6% 9% 9% 35%	720
	11th to 20th	Night	8% 6% 2 5% 6% 3 5% 7% 7% 11% 38%	780
	21st to end	Night	6% 6% 2 5% 5% 3 6% 5% 7% 12% 42%	1182
August	1st to 10th	Night	7% 6% 3 5% 6% 3 6% 5% 7% 8% 42%	1074
	11th to 20th	Night	11% 7% 2 6% 5% 4 6% 6% 7% 8% 36%	1375
	21st to end	Night	13% 9% 2 6% 6% 3 4 6% 6% 8% 37%	1603
September	1st to 10th	Night	15% 7% 3 6% 5% 3 4 5% 7% 9% 36%	1700
	11th to 20th	Night	12% 11% 3 7% 5% 3 5% 5% 6% 9% 35%	1839
	21st to end	Night	13% 10% 3 7% 8% 3 5% 5% 6% 8% 31%	1988
October	1st to 10th	Night	11% 13% 3 8% 6% 4 6% 5% 5% 7% 32%	2218
	11th to 20th	Night	11% 15% 5% 9% 7% 4 5% 4 5% 5% 29%	2340
	21st to end	Night	12% 20% 7% 11% 6% 4 6% 5% 5% 6% 18%	2813
November	1st to 10th	Night	14% 15% 6% 11% 9% 5% 5% 4 4 5% 22%	2775
	11th to 20th	Night	11% 16% 7% 12% 8% 4 6% 5% 6% 6% 20%	3045
	21st to end	Night	9% 15% 7% 12% 10% 5% 6% 6% 6% 7% 17%	3230
December	1st to 10th	Night	6% 14% 8% 12% 11% 6% 7% 6% 7% 8% 16%	3274
	11th to 20th	Night	7% 13% 7% 11% 9% 5% 6% 7% 7% 7% 21%	4233
	21st to end	Night	5% 12% 5% 10% 9% 5% 7% 8% 7% 8% 23%	6270

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	65% 4 11% 14% 5%	759
	11th to 20th	Day	64% 8% 11% 13% 4 1	998
	21st to end	Day	64% 5% 9% 15% 7%	1188
February	1st to 10th	Day	48% 6% 15% 24% 7%	1246
	11th to 20th	Day	58% 8% 15% 15% 4	1408
	21st to end	Day	54% 7% 13% 20% 6%	1242
March	1st to 10th	Day	48% 7% 16% 23% 5% 1	1800
	11th to 20th	Day	51% 7% 14% 20% 7%	1831
	21st to end	Day	43% 7% 18% 24% 7%	2376
April	1st to 10th	Day	49% 5% 16% 21% 8%	2227
	11th to 20th	Day	40% 6% 15% 31% 8%	2447
	21st to end	Day	48% 8% 15% 21% 7%	2596
May	1st to 10th	Day	42% 6% 16% 24% 10% 1	2790
	11th to 20th	Day	41% 7% 13% 26% 11% 1	2871
	21st to end	Day	35% 6% 14% 31% 13% 2	3325
June	1st to 10th	Day	44% 8% 15% 26% 6% 1	3240
	11th to 20th	Day	44% 10% 16% 21% 9%	3240
	21st to end	Day	38% 10% 19% 25% 7% 1	3240
July	1st to 10th	Day	46% 9% 20% 21% 3	3151
	11th to 20th	Day	40% 11% 20% 25% 4	3079
	21st to end	Day	34% 12% 25% 27% 1	2961
August	1st to 10th	Day	41% 9% 21% 24% 4	2846
	11th to 20th	Day	48% 11% 19% 17% 4	2523
	21st to end	Day	50% 9% 21% 19% 1	2753
September	1st to 10th	Day	46% 10% 23% 18% 3	2260
	11th to 20th	Day	45% 10% 23% 20% 2	2121
	21st to end	Day	51% 10% 22% 15% 3	1972
October	1st to 10th	Day	57% 8% 17% 17% 2	1742
	11th to 20th	Day	59% 8% 17% 15% 2	1620
	21st to end	Day	65% 8% 16% 10% 2	1522
November	1st to 10th	Day	66% 7% 16% 9% 2 1	1302
	11th to 20th	Day	67% 8% 13% 9% 3	1132
	21st to end	Day	67% 6% 13% 10% 4	950
December	1st to 10th	Day	65% 5% 11% 15% 4	903
	11th to 20th	Day	60% 9% 16% 9% 5%	960
	21st to end	Day	57% 7% 16% 14% 5%	1386
January	1st to 10th	Night	66% 6% 9% 15% 4	3406
	11th to 20th	Night	64% 7% 10% 14% 4	3034
	21st to end	Night	63% 7% 9% 15% 7%	3168
February	1st to 10th	Night	49% 8% 12% 22% 8%	2730
	11th to 20th	Night	57% 7% 13% 18% 4	2448
	21st to end	Night	56% 7% 12% 19% 6%	2013
March	1st to 10th	Night	44% 7% 17% 24% 7%	2160
	11th to 20th	Night	50% 7% 13% 22% 8%	2129
	21st to end	Night	43% 6% 17% 28% 6%	1980
April	1st to 10th	Night	50% 7% 12% 22% 8% 1	1732
	11th to 20th	Night	38% 6% 13% 27% 14% 1	1460
	21st to end	Night	46% 7% 13% 24% 9%	1364
May	1st to 10th	Night	40% 7% 16% 24% 12% 1	1170
	11th to 20th	Night	41% 8% 15% 24% 12%	1027
	21st to end	Night	37% 7% 9% 30% 14% 3	948
June	1st to 10th	Night	44% 9% 12% 27% 8%	720
	11th to 20th	Night	40% 8% 17% 23% 11% 1	720
	21st to end	Night	36% 10% 20% 28% 7%	720
July	1st to 10th	Night	40% 10% 21% 25% 3	700
	11th to 20th	Night	37% 11% 21% 27% 5%	756
	21st to end	Night	31% 10% 28% 29% 2	1116
August	1st to 10th	Night	36% 10% 21% 29% 3	1068
	11th to 20th	Night	42% 12% 23% 18% 4 1	1375
	21st to end	Night	43% 9% 22% 25% 1	1603
September	1st to 10th	Night	42% 10% 22% 22% 4	1700
	11th to 20th	Night	45% 8% 21% 21% 4	1839
	21st to end	Night	50% 9% 20% 19% 3	1988
October	1st to 10th	Night	51% 8% 19% 19% 2 1	2218
	11th to 20th	Night	56% 7% 18% 16% 3	2340
	21st to end	Night	66% 9% 15% 9% 1	2813
November	1st to 10th	Night	65% 6% 13% 12% 3	2775
	11th to 20th	Night	64% 9% 14% 11% 3	3045
	21st to end	Night	65% 7% 14% 12% 2	3230
December	1st to 10th	Night	65% 8% 13% 12% 2	3274
	11th to 20th	Night	58% 8% 14% 14% 5% 1	4231
	21st to end	Night	54% 8% 16% 18% 5%	6270

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	9% 8% 21% 32% 23% 7%	180
	11th to 20th	Day	19% 5% 16% 32% 16% 11%	166
	21st to end	Day	15% 3 23% 34% 20% 5%	176
February	1st to 10th	Day	5% 4 32% 33% 19% 7%	160
	11th to 20th	Day	4 6% 29% 36% 19% 5%	160
	21st to end	Day	3 8% 27% 30% 25% 8%	183
March	1st to 10th	Day	5% 8% 22% 29% 24% 11%	420
	11th to 20th	Day	10% 9% 30% 30% 17% 4	420
	21st to end	Day	10% 9% 30% 32% 16% 3	462
April	1st to 10th	Day	16% 10% 26% 29% 15% 5%	420
	11th to 20th	Day	10% 9% 23% 31% 20% 6%	412
	21st to end	Day	14% 10% 29% 29% 16% 3	496
May	1st to 10th	Day	13% 11% 27% 30% 16% 3	693
	11th to 20th	Day	14% 9% 27% 29% 16% 5%	802
	21st to end	Day	13% 8% 23% 33% 18% 5%	874
June	1st to 10th	Day	17% 7% 23% 29% 20% 5%	810
	11th to 20th	Day	13% 7% 21% 35% 19% 5%	810
	21st to end	Day	12% 6% 21% 31% 22% 8%	810
July	1st to 10th	Day	15% 5% 17% 32% 25% 7%	796
	11th to 20th	Day	11% 4 17% 34% 26% 7%	792
	21st to end	Day	11% 4 14% 33% 28% 10%	881
August	1st to 10th	Day	11% 5% 14% 32% 27% 10%	805
	11th to 20th	Day	17% 8% 25% 29% 16% 5%	485
	21st to end	Day	19% 5% 18% 32% 18% 8%	495
September	1st to 10th	Day	21% 8% 24% 22% 19% 6%	450
	11th to 20th	Day	16% 8% 25% 26% 18% 8%	450
	21st to end	Day	14% 9% 34% 26% 14% 3	450
October	1st to 10th	Day	20% 10% 28% 23% 15% 4	392
	11th to 20th	Day	21% 5% 29% 27% 16% 2	270
	21st to end	Day	18% 10% 25% 30% 11% 5%	219
November	1st to 10th	Day	14% 3 30% 27% 17% 9%	180
	11th to 20th	Day	18% 4 23% 37% 10% 8%	180
	21st to end	Day	18% 6% 24% 39% 11% 2	180
December	1st to 10th	Day	14% 6% 23% 31% 22% 4	180
	11th to 20th	Day	11% 3 23% 32% 23% 7%	180
	21st to end	Day	11% 3 16% 35% 25% 11%	198
January	1st to 10th	Night	13% 4 22% 33% 22% 6%	1040
	11th to 20th	Night	14% 4 21% 36% 21% 5%	1001
	21st to end	Night	15% 5% 23% 35% 19% 4	1078
February	1st to 10th	Night	6% 5% 23% 37% 22% 6%	858
	11th to 20th	Night	12% 5% 23% 35% 23% 2	704
	21st to end	Night	10% 4 22% 36% 25% 3	592
March	1st to 10th	Night	6% 4 24% 34% 25% 7%	720
	11th to 20th	Night	11% 6% 25% 35% 22% 1	720
	21st to end	Night	8% 4 25% 37% 22% 4	792
April	1st to 10th	Night	12% 7% 28% 31% 20% 3	652
	11th to 20th	Night	9% 6% 26% 38% 20% 1	392
	21st to end	Night	11% 8% 29% 33% 18% 2	360
May	1st to 10th	Night	9% 5% 31% 36% 17% 1	360
	11th to 20th	Night	12% 8% 23% 35% 20% 3	354
	21st to end	Night	13% 5% 24% 35% 22% 1	389
June	1st to 10th	Night	13% 5% 19% 36% 24% 3	360
	11th to 20th	Night	9% 4 18% 37% 28% 4	360
	21st to end	Night	11% 2 17% 34% 33% 4	360
July	1st to 10th	Night	12% 2 17% 35% 29% 4	350
	11th to 20th	Night	10% 2 17% 37% 31% 3	348
	21st to end	Night	8% 2 11% 37% 36% 6%	394
August	1st to 10th	Night	9% 4 14% 33% 29% 11%	358
	11th to 20th	Night	13% 4 20% 33% 27% 3	356
	21st to end	Night	16% 3 18% 30% 27% 6%	415
September	1st to 10th	Night	19% 5% 21% 29% 22% 5%	620
	11th to 20th	Night	18% 5% 19% 37% 17% 5%	720
	21st to end	Night	16% 8% 25% 33% 17% 2	720
October	1st to 10th	Night	16% 7% 22% 35% 17% 3	720
	11th to 20th	Night	21% 3 24% 32% 18% 3	720
	21st to end	Night	23% 5% 23% 27% 18% 4	877
November	1st to 10th	Night	21% 6% 20% 30% 19% 5%	925
	11th to 20th	Night	19% 5% 20% 33% 18% 5%	1014
	21st to end	Night	17% 5% 21% 34% 19% 4	1040
December	1st to 10th	Night	13% 4 20% 40% 19% 3	1040
	11th to 20th	Night	14% 4 21% 37% 21% 3	1040
	21st to end	Night	13% 3 17% 31% 29% 7%	1144

Page generated at 2024-01-11 02:22:42. Version ac07

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