Predator Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Predator Bay clear sky chart from 2005-11-06 to 2024-03-01.

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% 8% 3 7% 6% 3 5% 5% 6% 8% 38%	77932
	Night	7% 9% 4 8% 6% 3 5% 5% 6% 8% 38%	81435
Transparency	Day	42% 7% 15% 23% 11% 2	77639
	Night	42% 7% 15% 23% 11% 2	81309
Seeing	Day	12% 8% 26% 31% 18% 5%	14322
	Night	11% 6% 29% 37% 15% 2	23657

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	3 9% 7% 11% 7% 4 5% 5% 6% 9% 34%	2219
	11th to 20th	Day	4 8% 3 11% 7% 5% 6% 6% 8% 8% 34%	2262
	21st to end	Day	4 8% 3 7% 7% 4 5% 6% 6% 10% 40%	2794
February	1st to 10th	Day	4 10% 6% 10% 8% 5% 7% 6% 7% 7% 30%	1520
	11th to 20th	Day	5% 12% 5% 10% 7% 4 6% 6% 7% 8% 29%	1664
	21st to end	Day	4 11% 7% 8% 8% 5% 6% 5% 6% 8% 31%	1530
March	1st to 10th	Day	5% 10% 5% 9% 10% 4 6% 5% 7% 8% 32%	1801
	11th to 20th	Day	5% 11% 4 5% 7% 3 5% 6% 6% 9% 38%	1956
	21st to end	Day	8% 15% 5% 8% 7% 3 6% 5% 6% 9% 28%	2204
April	1st to 10th	Day	8% 14% 6% 9% 7% 4 5% 5% 6% 8% 28%	2209
	11th to 20th	Day	12% 13% 4 8% 6% 4 5% 6% 5% 8% 30%	2310
	21st to end	Day	13% 11% 4 7% 7% 3 6% 5% 5% 8% 32%	2340
May	1st to 10th	Day	13% 11% 4 8% 7% 3 5% 6% 7% 8% 29%	2443
	11th to 20th	Day	13% 7% 3 6% 7% 4 6% 6% 6% 8% 35%	2654
	21st to end	Day	21% 7% 3 6% 6% 3 5% 5% 7% 7% 30%	2917
June	1st to 10th	Day	17% 7% 3 7% 6% 4 5% 6% 7% 9% 29%	2700
	11th to 20th	Day	21% 8% 3 6% 6% 4 6% 6% 6% 8% 27%	2700
	21st to end	Day	9% 4 2 5% 5% 3 5% 7% 8% 10% 42%	2700
July	1st to 10th	Day	8% 5% 2 4 5% 3 6% 6% 6% 9% 44%	2700
	11th to 20th	Day	10% 4 2 4 4 3 5% 6% 7% 9% 46%	2700
	21st to end	Day	4 3 1 3 4 3 4 5% 7% 10% 54%	2865
August	1st to 10th	Day	10% 5% 2 4 4 3 4 5% 7% 9% 46%	2507
	11th to 20th	Day	9% 4 2 4 4 3 4 5% 7% 9% 50%	2318
	21st to end	Day	10% 5% 2 3 4 3 4 5% 6% 9% 49%	2574
September	1st to 10th	Day	11% 6% 2 5% 4 3 4 4 5% 6% 51%	2228
	11th to 20th	Day	14% 6% 2 5% 5% 3 4 4 5% 7% 45%	1980
	21st to end	Day	9% 8% 3 6% 4 3 4 5% 6% 8% 45%	1980
October	1st to 10th	Day	12% 10% 3 6% 5% 3 5% 4 5% 6% 40%	1904
	11th to 20th	Day	10% 9% 4 6% 5% 3 4 5% 7% 8% 39%	1670
	21st to end	Day	7% 10% 4 7% 7% 3 6% 5% 7% 8% 36%	1782
November	1st to 10th	Day	9% 13% 5% 9% 6% 3 5% 5% 4 8% 33%	1558
	11th to 20th	Day	7% 10% 3 7% 5% 4 4 4 7% 8% 41%	1459
	21st to end	Day	4 11% 5% 8% 5% 4 5% 5% 6% 11% 37%	1330
December	1st to 10th	Day	4 10% 6% 9% 7% 4 6% 5% 5% 8% 35%	1330
	11th to 20th	Day	2 11% 6% 11% 8% 5% 6% 6% 6% 6% 32%	1682
	21st to end	Day	3 8% 3 7% 6% 3 5% 5% 6% 8% 45%	2442
January	1st to 10th	Night	4 11% 6% 10% 10% 5% 7% 6% 6% 9% 28%	4726
	11th to 20th	Night	4 6% 5% 13% 7% 4 6% 7% 6% 8% 34%	4667
	21st to end	Night	4 10% 4 9% 8% 3 5% 4 6% 8% 39%	4862
February	1st to 10th	Night	5% 10% 5% 10% 7% 4 7% 6% 6% 8% 32%	2660
	11th to 20th	Night	6% 12% 5% 9% 7% 4 5% 6% 6% 8% 31%	2402
	21st to end	Night	3 9% 5% 12% 10% 5% 5% 5% 6% 7% 34%	1922
March	1st to 10th	Night	4 11% 5% 9% 8% 4 5% 7% 6% 9% 31%	2165
	11th to 20th	Night	5% 10% 5% 7% 6% 5% 6% 5% 6% 9% 36%	2003
	21st to end	Night	6% 11% 6% 10% 6% 4 5% 6% 7% 8% 31%	2150
April	1st to 10th	Night	9% 12% 6% 9% 7% 3 5% 5% 6% 8% 31%	1751
	11th to 20th	Night	12% 11% 5% 8% 6% 3 5% 5% 5% 8% 31%	1601
	21st to end	Night	11% 11% 4 7% 6% 3 6% 5% 6% 8% 34%	1620
May	1st to 10th	Night	11% 11% 4 8% 5% 2 6% 6% 5% 8% 34%	1513
	11th to 20th	Night	10% 7% 3 7% 4 3 5% 4 6% 9% 42%	1239
	21st to end	Night	19% 8% 3 6% 4 3 5% 5% 8% 9% 31%	1358
June	1st to 10th	Night	14% 7% 3 6% 7% 3 6% 5% 7% 8% 33%	1260
	11th to 20th	Night	19% 7% 3 6% 5% 3 5% 6% 6% 8% 32%	1260
	21st to end	Night	8% 4 1 5% 4 4 7% 6% 8% 10% 44%	1260
July	1st to 10th	Night	8% 5% 2 4 5% 3 4 5% 5% 8% 50%	1260
	11th to 20th	Night	7% 6% 2 5% 3 3 5% 6% 8% 9% 46%	1260
	21st to end	Night	5% 3 2 3 4 2 4 4 6% 8% 59%	1450
August	1st to 10th	Night	9% 5% 2 5% 6% 3 5% 4 6% 9% 47%	1432
	11th to 20th	Night	8% 5% 1 4 3 2 4 5% 7% 9% 51%	1582
	21st to end	Night	9% 4 2 5% 3 1 4 4 5% 10% 54%	1782
September	1st to 10th	Night	10% 7% 2 5% 5% 2 4 4 6% 9% 48%	1730
	11th to 20th	Night	13% 7% 2 4 4 2 3 3 5% 7% 50%	1980
	21st to end	Night	10% 6% 2 4 4 2 5% 5% 6% 8% 48%	1980
October	1st to 10th	Night	11% 9% 2 6% 5% 3 4 4 5% 6% 44%	2056
	11th to 20th	Night	8% 7% 2 5% 6% 3 5% 6% 6% 9% 42%	2288
	21st to end	Night	7% 10% 3 7% 6% 3 5% 6% 6% 8% 39%	2574
November	1st to 10th	Night	8% 13% 5% 7% 5% 4 5% 5% 5% 6% 36%	2501
	11th to 20th	Night	5% 9% 5% 7% 7% 4 5% 5% 6% 8% 41%	2717
	21st to end	Night	4 9% 5% 8% 6% 3 5% 5% 6% 8% 40%	2850
December	1st to 10th	Night	5% 10% 5% 9% 7% 4 7% 5% 5% 8% 35%	2850
	11th to 20th	Night	2 8% 4 10% 9% 4 7% 6% 7% 9% 33%	3510
	21st to end	Night	3 9% 4 7% 6% 3 5% 5% 6% 7% 44%	5214

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	44% 6% 14% 24% 10% 2	2219
	11th to 20th	Day	45% 6% 12% 17% 17% 4	2283
	21st to end	Day	37% 7% 15% 31% 9% 1	2794
February	1st to 10th	Day	50% 9% 15% 15% 9% 2	1520
	11th to 20th	Day	50% 6% 14% 19% 10% 2	1673
	21st to end	Day	49% 6% 14% 19% 12% 1	1530
March	1st to 10th	Day	48% 8% 17% 18% 9% 1	1801
	11th to 20th	Day	41% 7% 14% 24% 12% 2	1957
	21st to end	Day	52% 9% 15% 18% 6% 1	2204
April	1st to 10th	Day	53% 5% 16% 19% 7% 1	2209
	11th to 20th	Day	51% 6% 12% 19% 10% 1	2310
	21st to end	Day	49% 7% 14% 20% 9% 1	2340
May	1st to 10th	Day	50% 8% 14% 19% 8% 1	2443
	11th to 20th	Day	44% 8% 14% 23% 10% 1	2658
	21st to end	Day	51% 7% 14% 21% 7% 1	2918
June	1st to 10th	Day	49% 8% 14% 20% 8% 1	2700
	11th to 20th	Day	52% 8% 14% 17% 7% 2	2700
	21st to end	Day	33% 9% 20% 26% 10% 2	2700
July	1st to 10th	Day	34% 9% 18% 25% 12% 2	2626
	11th to 20th	Day	33% 9% 17% 27% 13% 1	2619
	21st to end	Day	23% 9% 18% 32% 16% 2	2706
August	1st to 10th	Day	32% 9% 17% 31% 10% 2	2490
	11th to 20th	Day	29% 7% 22% 29% 10% 2	2318
	21st to end	Day	29% 8% 17% 28% 15% 2	2574
September	1st to 10th	Day	33% 7% 15% 26% 15% 4	2228
	11th to 20th	Day	39% 6% 13% 27% 13% 2	1980
	21st to end	Day	37% 6% 14% 28% 12% 3	1980
October	1st to 10th	Day	43% 6% 14% 24% 10% 2	1904
	11th to 20th	Day	41% 7% 15% 26% 10% 3	1670
	21st to end	Day	43% 7% 13% 23% 11% 2	1782
November	1st to 10th	Day	50% 7% 11% 19% 11% 2	1558
	11th to 20th	Day	41% 6% 17% 25% 10% 1	1459
	21st to end	Day	41% 7% 16% 24% 9% 2	1330
December	1st to 10th	Day	48% 5% 13% 18% 12% 3	1330
	11th to 20th	Day	50% 6% 15% 20% 8% 1	1684
	21st to end	Day	35% 6% 12% 23% 18% 5%	2442
January	1st to 10th	Night	51% 7% 13% 21% 7% 2	4726
	11th to 20th	Night	47% 6% 12% 16% 14% 5%	4708
	21st to end	Night	42% 6% 15% 25% 12% 1	4862
February	1st to 10th	Night	49% 6% 12% 19% 11% 2	2660
	11th to 20th	Night	49% 6% 13% 20% 11% 1	2403
	21st to end	Night	48% 5% 11% 22% 11% 2	1922
March	1st to 10th	Night	47% 8% 15% 22% 7% 1	2165
	11th to 20th	Night	44% 6% 14% 22% 13% 1	2003
	21st to end	Night	49% 8% 15% 18% 8% 1	2150
April	1st to 10th	Night	51% 6% 11% 20% 11% 1	1751
	11th to 20th	Night	51% 6% 12% 20% 8% 1	1601
	21st to end	Night	46% 8% 15% 21% 9% 2	1620
May	1st to 10th	Night	47% 8% 14% 19% 11% 1	1513
	11th to 20th	Night	38% 8% 13% 28% 10% 1	1239
	21st to end	Night	49% 6% 16% 21% 6% 1	1358
June	1st to 10th	Night	47% 7% 14% 20% 11%	1260
	11th to 20th	Night	46% 9% 16% 19% 8% 2	1260
	21st to end	Night	32% 10% 20% 25% 11% 1	1260
July	1st to 10th	Night	33% 6% 20% 28% 12% 1	1225
	11th to 20th	Night	31% 10% 18% 26% 11% 3	1218
	21st to end	Night	23% 8% 17% 32% 18% 2	1370
August	1st to 10th	Night	33% 9% 17% 28% 12% 2	1424
	11th to 20th	Night	25% 10% 21% 30% 13% 1	1582
	21st to end	Night	27% 6% 15% 31% 17% 4	1782
September	1st to 10th	Night	33% 6% 15% 25% 15% 4	1730
	11th to 20th	Night	34% 6% 14% 28% 14% 5%	1980
	21st to end	Night	33% 6% 18% 25% 14% 4	1980
October	1st to 10th	Night	40% 6% 14% 24% 14% 1	2056
	11th to 20th	Night	36% 8% 17% 24% 13% 3	2288
	21st to end	Night	41% 7% 15% 24% 12% 1	2574
November	1st to 10th	Night	47% 6% 12% 21% 12% 2	2501
	11th to 20th	Night	41% 7% 15% 21% 14% 1	2717
	21st to end	Night	40% 6% 17% 23% 10% 3	2850
December	1st to 10th	Night	47% 7% 14% 20% 10% 3	2850
	11th to 20th	Night	43% 9% 18% 22% 6% 1	3507
	21st to end	Night	38% 5% 12% 26% 15% 4	5214

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	4 9% 22% 36% 17% 12%	180
	11th to 20th	Day	9% 4 24% 39% 17% 7%	180
	21st to end	Day	7% 9% 16% 45% 19% 4	198
February	1st to 10th	Day	10% 9% 27% 37% 13% 3	180
	11th to 20th	Day	7% 5% 33% 34% 19% 2	270
	21st to end	Day	7% 7% 27% 38% 18% 3	342
March	1st to 10th	Day	8% 11% 36% 27% 12% 5%	421
	11th to 20th	Day	9% 11% 27% 33% 15% 4	420
	21st to end	Day	11% 15% 31% 26% 12% 5%	462
April	1st to 10th	Day	13% 13% 35% 25% 12% 2	420
	11th to 20th	Day	15% 13% 25% 30% 13% 4	412
	21st to end	Day	16% 16% 28% 25% 13% 3	420
May	1st to 10th	Day	19% 9% 26% 24% 16% 6%	454
	11th to 20th	Day	18% 5% 22% 28% 21% 6%	625
	21st to end	Day	19% 6% 19% 28% 21% 6%	679
June	1st to 10th	Day	17% 7% 25% 31% 16% 4	630
	11th to 20th	Day	21% 9% 25% 29% 14% 2	630
	21st to end	Day	11% 5% 23% 33% 20% 7%	630
July	1st to 10th	Day	9% 5% 21% 32% 26% 7%	621
	11th to 20th	Day	11% 5% 22% 33% 23% 5%	618
	21st to end	Day	5% 7% 25% 34% 23% 7%	611
August	1st to 10th	Day	11% 5% 26% 31% 20% 7%	447
	11th to 20th	Day	9% 3 22% 34% 24% 8%	437
	21st to end	Day	11% 7% 23% 30% 19% 11%	495
September	1st to 10th	Day	13% 7% 27% 30% 18% 5%	450
	11th to 20th	Day	17% 6% 23% 30% 17% 7%	450
	21st to end	Day	13% 14% 26% 30% 13% 5%	450
October	1st to 10th	Day	14% 6% 26% 27% 22% 4	374
	11th to 20th	Day	14% 8% 28% 30% 16% 4	270
	21st to end	Day	14% 10% 34% 26% 13% 3	297
November	1st to 10th	Day	19% 7% 28% 32% 10% 4	270
	11th to 20th	Day	12% 8% 34% 32% 10% 3	241
	21st to end	Day	5% 9% 28% 32% 16% 10%	180
December	1st to 10th	Day	6% 5% 26% 43% 16% 5%	180
	11th to 20th	Day	6% 9% 31% 38% 12% 4	180
	21st to end	Day	8% 5% 19% 39% 22% 6%	198
January	1st to 10th	Night	9% 8% 31% 38% 12% 2	950
	11th to 20th	Night	8% 6% 34% 38% 13% 1	931
	21st to end	Night	9% 9% 31% 38% 11% 2	836
February	1st to 10th	Night	9% 7% 30% 34% 16% 4	760
	11th to 20th	Night	11% 6% 30% 40% 12% 1	744
	21st to end	Night	7% 5% 27% 38% 19% 4	628
March	1st to 10th	Night	8% 6% 32% 36% 14% 4	722
	11th to 20th	Night	9% 8% 31% 36% 13% 2	720
	21st to end	Night	13% 5% 30% 36% 14% 3	792
April	1st to 10th	Night	13% 7% 30% 34% 14% 2	671
	11th to 20th	Night	17% 7% 31% 33% 12%	533
	21st to end	Night	18% 7% 29% 32% 14%	540
May	1st to 10th	Night	17% 8% 24% 34% 17% 1	464
	11th to 20th	Night	13% 7% 24% 35% 21%	354
	21st to end	Night	22% 3 22% 33% 19% 1	389
June	1st to 10th	Night	16% 7% 25% 36% 15% 1	360
	11th to 20th	Night	22% 2 24% 37% 15%	360
	21st to end	Night	9% 4 17% 41% 27% 2	360
July	1st to 10th	Night	10% 4 15% 43% 27% 1	350
	11th to 20th	Night	10% 3 19% 45% 20% 3	348
	21st to end	Night	6% 3 19% 47% 24% 2	394
August	1st to 10th	Night	10% 4 12% 39% 32% 2	358
	11th to 20th	Night	9% 3 16% 46% 23% 2	514
	21st to end	Night	9% 3 21% 42% 24% 1	594
September	1st to 10th	Night	13% 5% 22% 37% 21% 3	632
	11th to 20th	Night	16% 4 19% 38% 20% 2	720
	21st to end	Night	13% 4 29% 36% 16% 3	720
October	1st to 10th	Night	15% 4 23% 39% 16% 2	720
	11th to 20th	Night	12% 4 30% 36% 15% 3	720
	21st to end	Night	11% 5% 33% 36% 12% 1	792
November	1st to 10th	Night	15% 8% 35% 31% 10% 1	836
	11th to 20th	Night	9% 9% 39% 32% 9% 1	950
	21st to end	Night	9% 6% 35% 36% 12% 2	950
December	1st to 10th	Night	9% 5% 33% 36% 14% 3	950
	11th to 20th	Night	6% 5% 36% 41% 10% 1	950
	21st to end	Night	9% 5% 31% 40% 12% 3	1045

Page generated at 2024-02-27 03:30:19. Version ac07

Copyright © 2024 Attilla Danko.