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 2024-11-12.

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	9% 9% 3 9% 6% 5% 5% 4 6% 8% 35%	106481
	Night	7% 12% 5% 11% 7% 6% 6% 5% 7% 7% 29%	101195
Transparency	Day	45% 8% 16% 23% 8%	106176
	Night	51% 8% 14% 20% 6%	101146
Seeing	Day	13% 7% 23% 31% 20% 6%	17308
	Night	13% 5% 22% 34% 22% 4	24876

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	4 14% 6% 19% 9% 8% 11% 5% 5% 8% 11%	1259
	11th to 20th	Day	4 12% 5% 12% 9% 6% 7% 5% 5% 7% 28%	1704
	21st to end	Day	7% 18% 6% 14% 8% 6% 6% 6% 5% 7% 17%	2090
February	1st to 10th	Day	4 8% 4 12% 8% 7% 6% 7% 8% 9% 27%	1315
	11th to 20th	Day	6% 12% 6% 13% 8% 6% 5% 4 7% 8% 25%	1480
	21st to end	Day	3 11% 6% 13% 7% 8% 7% 6% 8% 8% 25%	1318
March	1st to 10th	Day	4 10% 4 10% 8% 8% 8% 6% 8% 8% 26%	3138
	11th to 20th	Day	8% 16% 6% 15% 8% 6% 5% 4 5% 6% 23%	3237
	21st to end	Day	3 8% 2 9% 5% 5% 5% 5% 5% 8% 46%	4165
April	1st to 10th	Day	7% 13% 4 10% 7% 5% 5% 3 4 6% 37%	2351
	11th to 20th	Day	5% 9% 2 7% 6% 5% 5% 4 5% 7% 44%	2585
	21st to end	Day	6% 10% 4 10% 7% 6% 6% 5% 7% 8% 32%	2741
May	1st to 10th	Day	6% 6% 2 6% 4 5% 4 4 5% 7% 52%	4900
	11th to 20th	Day	9% 9% 3 8% 5% 5% 5% 5% 7% 8% 36%	5075
	21st to end	Day	10% 8% 2 6% 4 4 5% 4 7% 8% 43%	5904
June	1st to 10th	Day	13% 8% 3 8% 6% 5% 6% 5% 7% 9% 33%	3420
	11th to 20th	Day	10% 7% 3 8% 6% 6% 7% 5% 7% 9% 32%	3420
	21st to end	Day	9% 7% 3 6% 5% 6% 5% 6% 7% 10% 38%	3420
July	1st to 10th	Day	9% 6% 2 7% 6% 6% 6% 5% 9% 11% 33%	5700
	11th to 20th	Day	9% 5% 2 5% 4 4 4 4 6% 8% 49%	5568
	21st to end	Day	9% 6% 2 7% 5% 5% 6% 5% 7% 9% 39%	5486
August	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 4 5% 6% 51%	5024
	11th to 20th	Day	16% 6% 2 6% 4 4 4 3 5% 7% 43%	4404
	21st to end	Day	14% 8% 3 8% 5% 6% 6% 5% 6% 8% 31%	4817
September	1st to 10th	Day	15% 8% 3 7% 5% 5% 4 4 7% 8% 34%	2385
	11th to 20th	Day	14% 10% 2 7% 4 4 6% 4 6% 8% 36%	2238
	21st to end	Day	14% 10% 4 8% 5% 5% 6% 5% 6% 8% 29%	2081
October	1st to 10th	Day	7% 11% 4 10% 5% 5% 6% 5% 6% 7% 33%	3066
	11th to 20th	Day	12% 13% 5% 12% 6% 5% 6% 4 5% 7% 24%	2842
	21st to end	Day	8% 14% 5% 11% 7% 6% 7% 5% 6% 6% 24%	2639
November	1st to 10th	Day	13% 17% 5% 12% 8% 6% 5% 4 5% 5% 20%	1372
	11th to 20th	Day	9% 22% 7% 13% 6% 5% 5% 4 4 5% 20%	1139
	21st to end	Day	9% 18% 7% 11% 9% 9% 7% 4 4 5% 19%	950
December	1st to 10th	Day	9% 17% 7% 12% 9% 8% 5% 4 7% 6% 18%	903
	11th to 20th	Day	6% 11% 5% 15% 10% 8% 6% 5% 7% 10% 17%	959
	21st to end	Day	7% 13% 4 12% 7% 7% 8% 5% 8% 5% 25%	1386
January	1st to 10th	Night	5% 14% 8% 18% 10% 10% 8% 4 5% 4 13%	5686
	11th to 20th	Night	5% 10% 5% 11% 7% 7% 9% 6% 7% 8% 24%	5193
	21st to end	Night	6% 15% 6% 13% 7% 5% 7% 6% 7% 7% 21%	5566
February	1st to 10th	Night	4 8% 5% 13% 8% 6% 6% 6% 7% 9% 26%	2882
	11th to 20th	Night	5% 14% 6% 12% 8% 6% 6% 5% 5% 7% 26%	2586
	21st to end	Night	4 12% 4 13% 8% 8% 6% 5% 8% 7% 25%	2135
March	1st to 10th	Night	2 7% 4 10% 6% 7% 7% 5% 10% 9% 32%	3736
	11th to 20th	Night	4 14% 5% 13% 8% 7% 6% 4 6% 7% 25%	3742
	21st to end	Night	3 6% 3 6% 5% 5% 5% 4 7% 9% 47%	3488
April	1st to 10th	Night	7% 14% 4 10% 7% 5% 6% 4 5% 6% 33%	1828
	11th to 20th	Night	5% 9% 4 6% 6% 5% 5% 5% 7% 7% 43%	1542
	21st to end	Night	6% 9% 4 8% 8% 6% 6% 6% 6% 7% 35%	1439
May	1st to 10th	Night	6% 5% 3 5% 4 5% 5% 4 7% 9% 48%	2046
	11th to 20th	Night	8% 6% 3 7% 6% 6% 7% 6% 7% 11% 34%	1819
	21st to end	Night	10% 8% 3 7% 4 5% 4 5% 6% 8% 41%	1668
June	1st to 10th	Night	11% 7% 3 9% 6% 5% 6% 4 7% 6% 36%	760
	11th to 20th	Night	9% 6% 4 8% 5% 5% 5% 5% 9% 8% 36%	760
	21st to end	Night	8% 4 3 8% 4 6% 6% 7% 6% 9% 40%	760
July	1st to 10th	Night	7% 4 2 8% 6% 6% 7% 6% 11% 11% 31%	1260
	11th to 20th	Night	8% 6% 2 5% 5% 4 4 5% 7% 9% 44%	1376
	21st to end	Night	7% 5% 2 6% 5% 5% 6% 4 7% 10% 42%	2066
August	1st to 10th	Night	7% 5% 2 5% 4 3 4 4 6% 8% 52%	1892
	11th to 20th	Night	11% 7% 2 6% 3 5% 5% 4 6% 8% 43%	2422
	21st to end	Night	12% 8% 3 9% 5% 5% 5% 5% 6% 8% 35%	2841
September	1st to 10th	Night	15% 7% 2 7% 5% 4 4 4 7% 9% 37%	1795
	11th to 20th	Night	12% 11% 3 8% 5% 4 4 4 6% 9% 34%	1942
	21st to end	Night	13% 10% 3 9% 6% 5% 5% 4 6% 8% 31%	2099
October	1st to 10th	Night	8% 13% 3 8% 5% 6% 6% 4 6% 7% 33%	3910
	11th to 20th	Night	8% 14% 5% 12% 5% 5% 4 3 5% 5% 34%	4086
	21st to end	Night	9% 18% 6% 12% 6% 6% 6% 4 6% 6% 20%	4877
November	1st to 10th	Night	13% 17% 6% 13% 8% 6% 4 3 4 5% 21%	2925
	11th to 20th	Night	10% 18% 6% 14% 7% 5% 5% 4 6% 5% 20%	3061
	21st to end	Night	9% 17% 6% 13% 8% 7% 5% 5% 7% 6% 17%	3230
December	1st to 10th	Night	5% 16% 7% 14% 9% 7% 6% 4 7% 8% 16%	3274
	11th to 20th	Night	7% 14% 6% 13% 8% 6% 6% 5% 7% 7% 21%	4233
	21st to end	Night	5% 12% 4 12% 7% 7% 8% 6% 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	70% 5% 8% 14% 3	1259
	11th to 20th	Day	54% 6% 9% 18% 12% 1	1722
	21st to end	Day	65% 8% 10% 10% 6%	2090
February	1st to 10th	Day	49% 6% 14% 24% 7%	1315
	11th to 20th	Day	56% 8% 15% 16% 5%	1488
	21st to end	Day	54% 7% 13% 20% 7%	1318
March	1st to 10th	Day	50% 7% 15% 23% 3 1	3138
	11th to 20th	Day	63% 5% 9% 18% 4	3237
	21st to end	Day	36% 7% 15% 31% 11%	4165
April	1st to 10th	Day	48% 5% 16% 22% 9%	2351
	11th to 20th	Day	39% 6% 14% 32% 9%	2585
	21st to end	Day	47% 8% 15% 22% 7%	2741
May	1st to 10th	Day	31% 5% 11% 32% 19% 2	4900
	11th to 20th	Day	40% 9% 12% 25% 12% 2	5079
	21st to end	Day	36% 7% 11% 27% 18% 2	5905
June	1st to 10th	Day	45% 8% 15% 26% 6% 1	3420
	11th to 20th	Day	44% 10% 16% 22% 9%	3420
	21st to end	Day	38% 9% 18% 26% 8% 1	3420
July	1st to 10th	Day	41% 10% 28% 18% 2	5611
	11th to 20th	Day	32% 7% 17% 32% 11%	5469
	21st to end	Day	36% 10% 21% 31% 2	5313
August	1st to 10th	Day	33% 7% 17% 28% 14%	5005
	11th to 20th	Day	40% 8% 13% 20% 18%	4448
	21st to end	Day	49% 9% 21% 19% 1	4816
September	1st to 10th	Day	46% 10% 23% 19% 3	2385
	11th to 20th	Day	45% 9% 23% 21% 2	2238
	21st to end	Day	51% 10% 22% 15% 3	2081
October	1st to 10th	Day	48% 8% 18% 23% 3	3066
	11th to 20th	Day	59% 6% 17% 17% 1	2842
	21st to end	Day	59% 8% 17% 14% 2	2639
November	1st to 10th	Day	66% 7% 15% 9% 2 1	1372
	11th to 20th	Day	67% 8% 13% 9% 3	1139
	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	71% 6% 7% 12% 4	5686
	11th to 20th	Night	53% 6% 8% 20% 11% 1	5237
	21st to end	Night	57% 9% 12% 16% 5%	5566
February	1st to 10th	Night	50% 8% 12% 22% 8%	2882
	11th to 20th	Night	56% 7% 14% 19% 5%	2588
	21st to end	Night	55% 7% 12% 20% 6%	2135
March	1st to 10th	Night	41% 8% 17% 29% 4	3736
	11th to 20th	Night	57% 8% 10% 19% 7%	3743
	21st to end	Night	31% 6% 16% 33% 14% 1	3488
April	1st to 10th	Night	50% 7% 12% 22% 9% 1	1828
	11th to 20th	Night	37% 7% 13% 28% 14% 1	1542
	21st to end	Night	45% 7% 13% 24% 9%	1439
May	1st to 10th	Night	31% 6% 12% 29% 21% 1	2046
	11th to 20th	Night	40% 9% 12% 24% 15%	1819
	21st to end	Night	38% 7% 7% 26% 19% 2	1668
June	1st to 10th	Night	44% 9% 12% 27% 8%	760
	11th to 20th	Night	41% 8% 16% 24% 11% 1	760
	21st to end	Night	36% 10% 19% 28% 7%	760
July	1st to 10th	Night	40% 12% 29% 17% 2	1240
	11th to 20th	Night	33% 9% 19% 28% 11% 1	1352
	21st to end	Night	32% 10% 25% 31% 2	2000
August	1st to 10th	Night	29% 7% 22% 29% 13%	1886
	11th to 20th	Night	37% 9% 15% 18% 20%	2444
	21st to end	Night	46% 9% 21% 23% 1	2841
September	1st to 10th	Night	41% 9% 22% 23% 4	1795
	11th to 20th	Night	45% 8% 21% 21% 4	1942
	21st to end	Night	49% 9% 20% 19% 2	2099
October	1st to 10th	Night	46% 8% 18% 23% 4	3910
	11th to 20th	Night	52% 5% 15% 25% 3	4086
	21st to end	Night	62% 8% 15% 15% 1	4877
November	1st to 10th	Night	66% 6% 13% 12% 3	2925
	11th to 20th	Night	64% 9% 13% 11% 3	3061
	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	17% 5% 15% 30% 22% 11%	180
	21st to end	Day	14% 3 25% 35% 18% 4	198
February	1st to 10th	Day	6% 5% 32% 31% 19% 7%	180
	11th to 20th	Day	4 6% 31% 34% 20% 6%	180
	21st to end	Day	4 7% 28% 32% 22% 7%	205
March	1st to 10th	Day	5% 8% 21% 30% 24% 12%	460
	11th to 20th	Day	12% 9% 29% 30% 16% 4	460
	21st to end	Day	9% 9% 30% 32% 15% 4	506
April	1st to 10th	Day	15% 10% 26% 29% 15% 4	460
	11th to 20th	Day	10% 8% 22% 32% 21% 7%	452
	21st to end	Day	14% 9% 27% 29% 16% 4	541
May	1st to 10th	Day	13% 11% 27% 30% 16% 3	748
	11th to 20th	Day	14% 10% 26% 30% 16% 5%	862
	21st to end	Day	13% 8% 24% 34% 18% 4	940
June	1st to 10th	Day	18% 7% 24% 28% 19% 5%	870
	11th to 20th	Day	13% 7% 22% 34% 19% 5%	870
	21st to end	Day	11% 5% 22% 32% 22% 7%	870
July	1st to 10th	Day	14% 5% 18% 32% 24% 7%	856
	11th to 20th	Day	11% 4 17% 34% 27% 7%	852
	21st to end	Day	10% 5% 14% 33% 28% 10%	947
August	1st to 10th	Day	11% 5% 14% 33% 28% 10%	864
	11th to 20th	Day	17% 8% 24% 30% 16% 5%	527
	21st to end	Day	18% 6% 20% 31% 17% 8%	539
September	1st to 10th	Day	20% 9% 25% 22% 18% 5%	490
	11th to 20th	Day	14% 7% 26% 26% 19% 8%	490
	21st to end	Day	14% 10% 33% 27% 14% 3	490
October	1st to 10th	Day	18% 11% 27% 24% 15% 5%	428
	11th to 20th	Day	21% 5% 28% 28% 15% 2	300
	21st to end	Day	16% 9% 28% 30% 11% 5%	243
November	1st to 10th	Day	13% 5% 33% 26% 16% 9%	200
	11th to 20th	Day	18% 5% 23% 36% 10% 8%	182
	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	13% 4 20% 36% 21% 5%	1040
	21st to end	Night	14% 6% 23% 36% 18% 3	1144
February	1st to 10th	Night	6% 5% 24% 36% 22% 6%	910
	11th to 20th	Night	11% 5% 23% 36% 23% 2	744
	21st to end	Night	10% 4 21% 38% 25% 3	628
March	1st to 10th	Night	6% 4 24% 34% 25% 7%	760
	11th to 20th	Night	11% 6% 26% 34% 22% 1	760
	21st to end	Night	8% 3 25% 37% 22% 4	836
April	1st to 10th	Night	11% 7% 29% 30% 20% 3	688
	11th to 20th	Night	8% 6% 26% 38% 20% 1	414
	21st to end	Night	11% 7% 29% 33% 18% 2	380
May	1st to 10th	Night	9% 5% 30% 37% 18% 1	380
	11th to 20th	Night	12% 7% 23% 35% 20% 2	374
	21st to end	Night	12% 5% 23% 36% 22% 1	411
June	1st to 10th	Night	13% 5% 19% 36% 24% 3	380
	11th to 20th	Night	9% 4 18% 37% 28% 4	380
	21st to end	Night	11% 2 17% 34% 32% 4	380
July	1st to 10th	Night	12% 3 17% 36% 28% 4	370
	11th to 20th	Night	10% 2 17% 38% 30% 3	368
	21st to end	Night	8% 1 11% 38% 35% 5%	416
August	1st to 10th	Night	9% 4 13% 35% 29% 10%	378
	11th to 20th	Night	13% 4 20% 33% 27% 3	376
	21st to end	Night	16% 3 19% 30% 27% 6%	439
September	1st to 10th	Night	18% 5% 22% 29% 21% 5%	655
	11th to 20th	Night	18% 5% 19% 36% 17% 5%	760
	21st to end	Night	16% 7% 25% 34% 17% 2	760
October	1st to 10th	Night	16% 8% 22% 34% 18% 3	760
	11th to 20th	Night	20% 4 25% 31% 17% 3	760
	21st to end	Night	22% 6% 23% 27% 18% 4	926
November	1st to 10th	Night	20% 6% 21% 30% 19% 4	975
	11th to 20th	Night	19% 6% 20% 32% 18% 5%	1020
	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 2024-11-08 20:45:40. Version ac07

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