Traverse City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Traverse City clear sky chart from 2005-11-06 to 2024-11-04.

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	14% 11% 4 9% 5% 5% 4 3 5% 6% 33%	100932
	Night	14% 13% 5% 10% 6% 5% 4 3 4 6% 29%	98053
Transparency	Day	51% 6% 10% 21% 11% 1	104476
	Night	56% 5% 11% 18% 9% 1	102650
Seeing	Day	18% 12% 29% 25% 13% 4	15758
	Night	20% 9% 29% 30% 11% 1	25722

By Month

Percentage Cloud Cover SE (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	11% 25% 15% 19% 8% 5% 3 2 3 3 6%	2527
	11th to 20th	Day	13% 18% 8% 21% 14% 11% 4 2 2 2 4	2530
	21st to end	Day	18% 21% 10% 14% 8% 6% 5% 3 3 3 8%	2783
February	1st to 10th	Day	8% 19% 6% 16% 15% 7% 5% 2 4 3 13%	1626
	11th to 20th	Day	11% 15% 7% 16% 12% 7% 5% 3 4 4 15%	1848
	21st to end	Day	12% 17% 7% 13% 9% 6% 5% 4 5% 5% 19%	1570
March	1st to 10th	Day	13% 13% 4 9% 6% 4 3 4 5% 6% 32%	3120
	11th to 20th	Day	9% 12% 6% 16% 5% 5% 4 4 5% 7% 28%	3375
	21st to end	Day	16% 13% 7% 15% 7% 4 4 3 4 5% 22%	3970
April	1st to 10th	Day	17% 15% 4 8% 5% 4 5% 3 4 5% 30%	2280
	11th to 20th	Day	19% 12% 4 6% 4 4 4 3 4 5% 34%	2342
	21st to end	Day	15% 11% 4 8% 4 4 4 4 6% 7% 34%	2470
May	1st to 10th	Day	14% 8% 3 6% 5% 4 3 3 5% 6% 43%	4082
	11th to 20th	Day	11% 7% 2 6% 4 4 4 4 4 7% 48%	4236
	21st to end	Day	12% 7% 2 6% 4 5% 4 4 5% 8% 44%	4824
June	1st to 10th	Day	14% 6% 1 6% 4 4 4 4 6% 7% 44%	2660
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 4 6% 9% 43%	2660
	21st to end	Day	13% 6% 2 6% 4 4 4 5% 6% 8% 42%	2660
July	1st to 10th	Day	17% 6% 2 6% 3 3 4 3 6% 8% 42%	4440
	11th to 20th	Day	9% 4 2 4 3 4 4 3 6% 8% 52%	4440
	21st to end	Day	9% 5% 2 5% 4 4 4 3 6% 9% 50%	4813
August	1st to 10th	Day	8% 5% 2 6% 5% 5% 6% 5% 7% 9% 42%	4263
	11th to 20th	Day	14% 5% 2 5% 3 4 4 3 5% 6% 48%	4044
	21st to end	Day	13% 6% 3 7% 4 4 4 3 5% 6% 45%	4318
September	1st to 10th	Day	15% 4 2 6% 4 5% 4 3 6% 7% 44%	2261
	11th to 20th	Day	14% 5% 2 5% 3 3 4 5% 5% 8% 46%	2090
	21st to end	Day	16% 7% 2 7% 3 4 5% 4 7% 8% 38%	2090
October	1st to 10th	Day	18% 8% 3 7% 4 4 3 4 5% 7% 37%	2090
	11th to 20th	Day	22% 16% 4 8% 6% 5% 6% 2 5% 6% 22%	1800
	21st to end	Day	23% 16% 4 10% 5% 6% 5% 4 6% 5% 17%	1881
November	1st to 10th	Day	16% 18% 5% 7% 5% 4 4 3 5% 7% 27%	1699
	11th to 20th	Day	12% 23% 6% 13% 5% 6% 5% 3 5% 6% 16%	1710
	21st to end	Day	16% 25% 8% 13% 5% 4 3 2 4 5% 14%	1633
December	1st to 10th	Day	15% 23% 11% 18% 7% 5% 4 2 3 3 9%	1330
	11th to 20th	Day	14% 21% 8% 16% 9% 6% 4 3 4 5% 10%	1684
	21st to end	Day	18% 22% 11% 13% 7% 6% 4 3 3 4 9%	2783
January	1st to 10th	Night	13% 25% 9% 19% 7% 6% 3 2 2 3 11%	4428
	11th to 20th	Night	11% 18% 8% 20% 15% 9% 4 3 3 3 7%	4440
	21st to end	Night	15% 23% 10% 14% 8% 7% 5% 3 3 3 8%	4884
February	1st to 10th	Night	10% 19% 7% 16% 13% 8% 5% 4 3 3 13%	2549
	11th to 20th	Night	11% 15% 8% 16% 10% 6% 4 3 5% 4 18%	2218
	21st to end	Night	14% 17% 6% 15% 7% 4 4 3 4 5% 21%	1884
March	1st to 10th	Night	15% 11% 4 7% 4 3 4 3 5% 6% 39%	3733
	11th to 20th	Night	8% 15% 5% 9% 6% 4 4 3 4 6% 36%	3584
	21st to end	Night	15% 13% 6% 11% 6% 4 5% 4 5% 5% 26%	3690
April	1st to 10th	Night	18% 14% 3 8% 4 4 4 4 5% 6% 30%	1900
	11th to 20th	Night	21% 10% 3 7% 4 3 3 3 4 7% 34%	1787
	21st to end	Night	16% 10% 3 6% 4 4 4 4 4 6% 37%	1710
May	1st to 10th	Night	15% 8% 2 7% 4 4 4 3 5% 6% 40%	2813
	11th to 20th	Night	14% 7% 2 7% 4 4 5% 4 6% 6% 43%	2661
	21st to end	Night	18% 6% 2 5% 3 4 3 3 5% 8% 42%	2743
June	1st to 10th	Night	15% 5% 2 6% 5% 3 5% 4 5% 7% 43%	1520
	11th to 20th	Night	12% 6% 2 6% 4 4 5% 5% 6% 9% 43%	1432
	21st to end	Night	11% 6% 2 6% 5% 3 4 3 5% 8% 46%	1520
July	1st to 10th	Night	13% 7% 2 6% 3 4 5% 4 5% 9% 42%	2530
	11th to 20th	Night	7% 5% 2 5% 4 4 4 4 6% 7% 53%	2530
	21st to end	Night	9% 5% 3 6% 4 4 4 3 5% 7% 48%	2750
August	1st to 10th	Night	11% 6% 3 8% 5% 5% 5% 3 6% 8% 42%	2671
	11th to 20th	Night	15% 4 2 5% 3 3 4 3 5% 7% 49%	2785
	21st to end	Night	13% 5% 2 6% 3 4 4 3 5% 7% 48%	3336
September	1st to 10th	Night	11% 7% 3 6% 4 3 4 3 5% 5% 49%	1900
	11th to 20th	Night	14% 5% 2 6% 4 3 3 3 6% 7% 47%	2090
	21st to end	Night	18% 6% 2 7% 5% 3 4 3 5% 7% 39%	2090
October	1st to 10th	Night	17% 9% 2 8% 5% 4 4 3 4 6% 39%	2090
	11th to 20th	Night	22% 12% 3 9% 5% 4 5% 3 5% 6% 26%	2379
	21st to end	Night	23% 15% 4 10% 6% 4 4 3 4 5% 23%	2717
November	1st to 10th	Night	14% 16% 3 9% 5% 5% 4 4 5% 6% 28%	2452
	11th to 20th	Night	14% 22% 6% 11% 6% 5% 5% 4 4 5% 18%	2470
	21st to end	Night	17% 21% 7% 13% 6% 5% 5% 4 4 5% 15%	2540
December	1st to 10th	Night	14% 22% 10% 17% 8% 5% 5% 3 4 4 10%	2850
	11th to 20th	Night	13% 20% 8% 19% 9% 5% 5% 4 5% 4 10%	3493
	21st to end	Night	22% 22% 9% 13% 6% 5% 4 3 3 4 9%	4884

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	87% 3 5% 4 1	2528
	11th to 20th	Day	89% 3 4 3 1	2530
	21st to end	Day	81% 5% 9% 4 1	2783
February	1st to 10th	Day	77% 4 8% 9% 2	1626
	11th to 20th	Day	73% 5% 9% 9% 4	1858
	21st to end	Day	67% 5% 9% 15% 3 1	1570
March	1st to 10th	Day	53% 6% 11% 20% 9% 1	3120
	11th to 20th	Day	55% 6% 11% 19% 6% 1	3375
	21st to end	Day	64% 7% 8% 15% 5% 1	3970
April	1st to 10th	Day	57% 5% 9% 18% 11%	2280
	11th to 20th	Day	52% 5% 8% 19% 14% 1	2342
	21st to end	Day	48% 7% 10% 15% 16% 3	2470
May	1st to 10th	Day	42% 6% 8% 24% 19% 2	4120
	11th to 20th	Day	36% 6% 9% 29% 18% 2	4240
	21st to end	Day	38% 7% 10% 22% 21% 2	4837
June	1st to 10th	Day	38% 7% 10% 27% 17% 2	2660
	11th to 20th	Day	38% 6% 12% 24% 20% 2	2660
	21st to end	Day	39% 7% 12% 26% 15% 1	2660
July	1st to 10th	Day	41% 5% 13% 24% 14% 2	4371
	11th to 20th	Day	28% 6% 13% 36% 16% 1	4365
	21st to end	Day	30% 8% 12% 28% 21% 1	4662
August	1st to 10th	Day	36% 7% 13% 29% 14% 1	4248
	11th to 20th	Day	37% 6% 11% 33% 13% 1	4083
	21st to end	Day	40% 6% 11% 29% 12% 1	4317
September	1st to 10th	Day	39% 7% 12% 26% 15% 2	2261
	11th to 20th	Day	35% 7% 14% 29% 14% 1	2090
	21st to end	Day	43% 7% 14% 25% 10%	2090
October	1st to 10th	Day	33% 5% 8% 34% 19% 1	3480
	11th to 20th	Day	56% 4 9% 19% 11%	2964
	21st to end	Day	64% 5% 13% 15% 3	3081
November	1st to 10th	Day	58% 5% 10% 18% 8%	1699
	11th to 20th	Day	69% 5% 12% 10% 4	1710
	21st to end	Day	73% 5% 12% 8% 1	1633
December	1st to 10th	Day	83% 4 6% 6% 1	1330
	11th to 20th	Day	79% 5% 9% 6% 1	1680
	21st to end	Day	80% 7% 7% 4 2	2783
January	1st to 10th	Night	81% 4 7% 8% 1	4428
	11th to 20th	Night	85% 4 6% 4 1	4440
	21st to end	Night	82% 6% 7% 5% 1	4884
February	1st to 10th	Night	75% 3 8% 10% 4	2549
	11th to 20th	Night	69% 6% 9% 13% 3	2219
	21st to end	Night	65% 5% 11% 15% 4	1884
March	1st to 10th	Night	47% 5% 17% 23% 9%	3733
	11th to 20th	Night	49% 5% 12% 24% 9% 1	3584
	21st to end	Night	58% 6% 12% 18% 7% 1	3690
April	1st to 10th	Night	54% 5% 10% 20% 11% 1	1900
	11th to 20th	Night	52% 4 7% 20% 14% 3	1787
	21st to end	Night	48% 4 10% 21% 14% 3	1710
May	1st to 10th	Night	43% 7% 11% 19% 17% 3	2840
	11th to 20th	Night	41% 6% 8% 27% 17% 2	2662
	21st to end	Night	40% 7% 13% 20% 16% 4	2751
June	1st to 10th	Night	39% 6% 11% 28% 15% 1	1520
	11th to 20th	Night	35% 7% 13% 25% 17% 2	1432
	21st to end	Night	37% 6% 13% 26% 16% 2	1520
July	1st to 10th	Night	40% 5% 13% 24% 14% 4	2490
	11th to 20th	Night	28% 7% 15% 31% 18% 1	2482
	21st to end	Night	34% 7% 13% 26% 20% 1	2662
August	1st to 10th	Night	40% 7% 14% 25% 13% 1	2662
	11th to 20th	Night	35% 5% 16% 29% 15% 1	2812
	21st to end	Night	35% 6% 15% 24% 19% 1	3336
September	1st to 10th	Night	36% 7% 11% 24% 21% 1	1900
	11th to 20th	Night	36% 5% 14% 30% 14%	2090
	21st to end	Night	43% 6% 15% 25% 10% 1	2090
October	1st to 10th	Night	40% 6% 10% 31% 13% 1	3480
	11th to 20th	Night	50% 5% 10% 23% 12%	3954
	21st to end	Night	55% 5% 12% 22% 6%	4467
November	1st to 10th	Night	56% 6% 13% 18% 7% 1	2452
	11th to 20th	Night	68% 5% 12% 10% 5% 1	2470
	21st to end	Night	73% 5% 12% 9% 2	2540
December	1st to 10th	Night	79% 5% 7% 7% 1	2850
	11th to 20th	Night	78% 6% 10% 4 2	3496
	21st to end	Night	79% 6% 10% 4 1	4884

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	18% 15% 38% 21% 7% 1	270
	11th to 20th	Day	21% 13% 40% 20% 6%	270
	21st to end	Day	24% 14% 31% 25% 6% 1	297
February	1st to 10th	Day	17% 23% 37% 17% 4 3	270
	11th to 20th	Day	19% 22% 37% 19% 4	270
	21st to end	Day	21% 25% 40% 12% 2	225
March	1st to 10th	Day	21% 20% 39% 17% 3	270
	11th to 20th	Day	24% 13% 30% 24% 9% 2	394
	21st to end	Day	27% 13% 28% 22% 9% 1	506
April	1st to 10th	Day	26% 14% 31% 23% 5% 2	460
	11th to 20th	Day	25% 20% 27% 16% 9% 3	452
	21st to end	Day	20% 15% 27% 24% 10% 3	460
May	1st to 10th	Day	20% 15% 31% 20% 11% 3	463
	11th to 20th	Day	14% 10% 30% 31% 11% 4	577
	21st to end	Day	13% 9% 28% 29% 16% 4	734
June	1st to 10th	Day	15% 9% 29% 29% 14% 4	680
	11th to 20th	Day	14% 10% 29% 31% 12% 4	680
	21st to end	Day	15% 8% 28% 30% 15% 4	680
July	1st to 10th	Day	9% 6% 27% 31% 19% 7%	671
	11th to 20th	Day	12% 7% 25% 32% 17% 7%	668
	21st to end	Day	9% 5% 27% 34% 19% 5%	739
August	1st to 10th	Day	10% 6% 22% 31% 23% 8%	581
	11th to 20th	Day	12% 5% 20% 29% 23% 11%	479
	21st to end	Day	17% 8% 21% 28% 21% 6%	539
September	1st to 10th	Day	17% 8% 22% 28% 18% 8%	490
	11th to 20th	Day	12% 6% 19% 30% 24% 9%	490
	21st to end	Day	19% 9% 19% 27% 20% 6%	490
October	1st to 10th	Day	22% 12% 26% 24% 14% 4	490
	11th to 20th	Day	27% 16% 29% 23% 5%	366
	21st to end	Day	31% 17% 32% 15% 5% 1	330
November	1st to 10th	Day	26% 16% 32% 16% 9%	279
	11th to 20th	Day	19% 20% 41% 16% 4	270
	21st to end	Day	24% 23% 36% 14% 3	257
December	1st to 10th	Day	29% 16% 33% 16% 6% 1	180
	11th to 20th	Day	22% 22% 36% 16% 3 1	184
	21st to end	Day	23% 20% 38% 15% 3 1	297
January	1st to 10th	Night	20% 13% 34% 24% 7% 1	950
	11th to 20th	Night	23% 13% 34% 23% 7% 1	950
	21st to end	Night	18% 10% 34% 29% 8% 1	1045
February	1st to 10th	Night	17% 11% 37% 28% 7% 1	851
	11th to 20th	Night	20% 14% 36% 24% 6%	743
	21st to end	Night	23% 15% 33% 24% 5%	628
March	1st to 10th	Night	16% 10% 34% 28% 10% 1	760
	11th to 20th	Night	17% 12% 34% 31% 5% 1	760
	21st to end	Night	19% 10% 29% 33% 7% 1	760
April	1st to 10th	Night	24% 8% 32% 29% 6% 1	570
	11th to 20th	Night	24% 13% 28% 26% 9% 1	563
	21st to end	Night	19% 9% 30% 32% 9% 1	570
May	1st to 10th	Night	17% 6% 31% 35% 11% 1	570
	11th to 20th	Night	19% 6% 26% 35% 13%	561
	21st to end	Night	15% 5% 25% 36% 18% 1	617
June	1st to 10th	Night	17% 5% 28% 35% 14% 1	570
	11th to 20th	Night	13% 6% 22% 44% 14% 1	482
	21st to end	Night	14% 4 25% 37% 20% 1	570
July	1st to 10th	Night	11% 3 17% 41% 26% 2	555
	11th to 20th	Night	11% 3 20% 38% 26% 2	552
	21st to end	Night	10% 3 18% 41% 25% 2	624
August	1st to 10th	Night	10% 2 16% 43% 28% 1	567
	11th to 20th	Night	9% 3 18% 38% 27% 4	564
	21st to end	Night	13% 4 18% 41% 22% 2	627
September	1st to 10th	Night	15% 5% 22% 33% 22% 4	570
	11th to 20th	Night	16% 3 20% 34% 23% 4	760
	21st to end	Night	21% 6% 20% 31% 18% 4	760
October	1st to 10th	Night	20% 8% 25% 29% 16% 1	760
	11th to 20th	Night	29% 10% 28% 27% 6% 1	760
	21st to end	Night	30% 12% 28% 24% 6%	836
November	1st to 10th	Night	25% 11% 30% 27% 6%	755
	11th to 20th	Night	24% 15% 35% 22% 4	760
	21st to end	Night	27% 12% 36% 22% 3	807
December	1st to 10th	Night	24% 15% 36% 21% 4	950
	11th to 20th	Night	22% 15% 36% 21% 4 1	950
	21st to end	Night	27% 12% 37% 21% 3	1045

Page generated at 2024-11-01 22:47:33. Version ac07

Copyright © 2024 Attilla Danko.