Memphis
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Memphis 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	12% 6% 2 6% 4 4 4 4 6% 7% 44%	100805
	Night	13% 6% 2 5% 4 3 4 3 5% 7% 49%	98241
Transparency	Day	37% 6% 10% 23% 19% 4	104481
	Night	34% 5% 10% 23% 21% 7%	102707
Seeing	Day	15% 8% 22% 26% 20% 9%	15328
	Night	15% 7% 25% 31% 19% 3	25083

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	15% 13% 4 7% 3 2 3 2 3 4 44%	2659
	11th to 20th	Day	20% 8% 2 6% 4 3 3 2 3 4 42%	2850
	21st to end	Day	22% 11% 3 6% 4 2 3 2 4 4 39%	3135
February	1st to 10th	Day	20% 9% 4 7% 3 3 3 2 4 5% 39%	1834
	11th to 20th	Day	20% 9% 3 6% 4 3 3 2 4 5% 39%	1848
	21st to end	Day	25% 8% 3 7% 4 3 3 3 4 5% 36%	1570
March	1st to 10th	Day	18% 12% 3 9% 5% 4 4 3 4 5% 34%	3170
	11th to 20th	Day	14% 7% 3 7% 5% 4 4 3 4 5% 43%	3480
	21st to end	Day	13% 8% 3 7% 6% 5% 4 4 5% 5% 41%	4034
April	1st to 10th	Day	12% 6% 3 6% 4 4 4 3 6% 7% 44%	2280
	11th to 20th	Day	15% 6% 2 5% 4 3 4 3 5% 7% 44%	2254
	21st to end	Day	14% 6% 3 6% 5% 4 4 4 5% 7% 42%	2280
May	1st to 10th	Day	13% 6% 2 7% 5% 4 4 4 6% 8% 40%	3765
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 6% 10% 39%	3973
	21st to end	Day	11% 6% 3 7% 6% 5% 6% 5% 7% 9% 35%	4720
June	1st to 10th	Day	8% 5% 2 7% 4 4 6% 4 8% 9% 43%	2660
	11th to 20th	Day	4 4 1 6% 5% 4 6% 5% 8% 10% 48%	2660
	21st to end	Day	5% 3 1 5% 5% 5% 5% 5% 8% 10% 49%	2660
July	1st to 10th	Day	7% 5% 2 6% 6% 6% 6% 5% 8% 10% 39%	4440
	11th to 20th	Day	8% 5% 2 6% 5% 5% 6% 5% 8% 11% 39%	4230
	21st to end	Day	15% 7% 3 9% 5% 5% 5% 5% 6% 7% 32%	4465
August	1st to 10th	Day	4 3 1 4 3 4 4 4 7% 9% 60%	3826
	11th to 20th	Day	7% 4 2 6% 4 5% 6% 4 7% 9% 47%	3729
	21st to end	Day	6% 4 2 5% 4 4 4 4 6% 8% 53%	4180
September	1st to 10th	Day	9% 4 2 6% 5% 5% 5% 5% 5% 8% 45%	2280
	11th to 20th	Day	12% 5% 2 6% 4 4 4 4 6% 8% 45%	2228
	21st to end	Day	12% 5% 1 5% 3 3 3 3 4 6% 55%	2090
October	1st to 10th	Day	7% 4 2 4 4 4 4 2 4 6% 59%	1961
	11th to 20th	Day	12% 5% 2 3 2 3 3 3 5% 6% 56%	1900
	21st to end	Day	18% 6% 2 3 2 3 3 3 3 4 53%	2090
November	1st to 10th	Day	12% 6% 2 3 2 3 3 2 4 6% 59%	1756
	11th to 20th	Day	13% 6% 2 5% 4 3 3 3 4 6% 52%	1710
	21st to end	Day	19% 7% 2 6% 4 3 4 3 4 6% 43%	1710
December	1st to 10th	Day	20% 9% 3 5% 4 3 4 3 4 5% 40%	1677
	11th to 20th	Day	15% 8% 3 6% 5% 4 4 3 3 4 44%	1918
	21st to end	Day	15% 11% 3 8% 4 4 5% 4 5% 6% 35%	2783
January	1st to 10th	Night	19% 8% 2 5% 4 3 3 3 4 4 45%	4291
	11th to 20th	Night	18% 7% 2 5% 3 4 4 2 3 4 47%	4120
	21st to end	Night	24% 8% 2 5% 2 2 2 3 3 4 45%	4532
February	1st to 10th	Night	21% 8% 3 7% 4 3 3 2 4 5% 41%	2343
	11th to 20th	Night	18% 8% 3 5% 5% 4 3 2 3 5% 43%	2218
	21st to end	Night	20% 8% 3 6% 4 3 3 3 3 5% 41%	1884
March	1st to 10th	Night	19% 9% 3 6% 4 3 3 3 4 5% 40%	3711
	11th to 20th	Night	15% 6% 2 6% 4 3 3 3 4 5% 50%	3480
	21st to end	Night	13% 6% 2 6% 4 4 4 4 6% 6% 44%	3595
April	1st to 10th	Night	11% 5% 2 5% 4 4 5% 3 5% 7% 49%	1900
	11th to 20th	Night	14% 5% 2 5% 3 3 3 3 4 6% 51%	1875
	21st to end	Night	12% 5% 2 6% 4 4 4 3 5% 6% 49%	1900
May	1st to 10th	Night	18% 7% 3 6% 3 2 4 3 5% 8% 41%	3130
	11th to 20th	Night	12% 7% 2 6% 4 4 4 3 6% 7% 44%	2918
	21st to end	Night	9% 6% 2 6% 5% 5% 5% 4 7% 10% 40%	2839
June	1st to 10th	Night	8% 4 2 5% 4 5% 5% 4 7% 10% 47%	1520
	11th to 20th	Night	2 3 1 3 3 2 4 4 7% 10% 61%	1520
	21st to end	Night	3 3 1 3 4 4 4 6% 6% 11% 55%	1520
July	1st to 10th	Night	6% 3 2 5% 5% 4 4 4 6% 13% 49%	2530
	11th to 20th	Night	6% 4 2 4 4 4 5% 3 5% 11% 53%	2721
	21st to end	Night	12% 7% 3 7% 5% 4 4 4 5% 8% 41%	3098
August	1st to 10th	Night	2 1 1 2 2 3 3 3 4 7% 71%	3104
	11th to 20th	Night	4 3 2 4 3 4 5% 4 7% 11% 55%	3100
	21st to end	Night	4 3 1 5% 3 4 4 4 6% 8% 58%	3476
September	1st to 10th	Night	8% 4 2 6% 3 3 4 3 5% 6% 53%	1900
	11th to 20th	Night	10% 6% 2 5% 3 3 4 5% 5% 6% 51%	1932
	21st to end	Night	10% 4 2 5% 4 3 3 3 3 6% 57%	2090
October	1st to 10th	Night	6% 3 2 5% 2 3 3 3 5% 7% 62%	2215
	11th to 20th	Night	10% 4 2 5% 3 2 3 2 4 6% 59%	2280
	21st to end	Night	17% 5% 2 4 3 3 3 3 3 4 54%	2508
November	1st to 10th	Night	11% 4 2 4 4 4 3 3 4 6% 56%	2390
	11th to 20th	Night	11% 4 2 5% 3 3 4 3 5% 6% 54%	2470
	21st to end	Night	15% 5% 2 5% 3 4 4 3 4 6% 49%	2470
December	1st to 10th	Night	17% 8% 2 6% 4 3 3 3 4 6% 45%	2498
	11th to 20th	Night	16% 7% 2 5% 4 3 3 3 5% 5% 47%	3279
	21st to end	Night	15% 8% 3 7% 5% 5% 5% 4 5% 6% 37%	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	46% 3 5% 23% 20% 3	2660
	11th to 20th	Day	45% 5% 8% 22% 19% 1	2850
	21st to end	Day	49% 3 7% 19% 20% 2	3135
February	1st to 10th	Day	49% 4 7% 22% 15% 2	1834
	11th to 20th	Day	48% 5% 7% 17% 18% 5%	1858
	21st to end	Day	52% 4 8% 15% 16% 6%	1570
March	1st to 10th	Day	52% 6% 7% 12% 15% 9%	3170
	11th to 20th	Day	41% 6% 8% 23% 18% 4	3480
	21st to end	Day	44% 5% 8% 22% 20% 1	4034
April	1st to 10th	Day	39% 6% 9% 23% 20% 2	2280
	11th to 20th	Day	39% 5% 8% 22% 20% 6%	2254
	21st to end	Day	41% 5% 9% 25% 18% 2	2280
May	1st to 10th	Day	40% 9% 12% 24% 14% 2	3800
	11th to 20th	Day	38% 10% 17% 22% 13% 1	3977
	21st to end	Day	40% 11% 13% 26% 9% 1	4733
June	1st to 10th	Day	34% 9% 13% 24% 19% 2	2660
	11th to 20th	Day	28% 8% 14% 29% 18% 4	2660
	21st to end	Day	28% 9% 13% 27% 19% 4	2660
July	1st to 10th	Day	37% 7% 15% 26% 13% 2	4371
	11th to 20th	Day	36% 7% 12% 32% 11% 2	4157
	21st to end	Day	50% 7% 13% 23% 7% 1	4325
August	1st to 10th	Day	20% 5% 17% 30% 23% 4	3812
	11th to 20th	Day	33% 6% 17% 26% 17% 2	3765
	21st to end	Day	30% 5% 11% 27% 24% 3	4179
September	1st to 10th	Day	35% 9% 11% 24% 17% 6%	2280
	11th to 20th	Day	37% 7% 10% 17% 24% 6%	2228
	21st to end	Day	31% 4 10% 22% 26% 7%	2090
October	1st to 10th	Day	17% 2 6% 14% 34% 26%	3260
	11th to 20th	Day	18% 3 4 22% 38% 15%	3140
	21st to end	Day	27% 2 4 27% 31% 9%	3428
November	1st to 10th	Day	29% 3 8% 26% 25% 9%	1756
	11th to 20th	Day	34% 4 9% 21% 25% 8%	1710
	21st to end	Day	43% 4 7% 19% 23% 4	1710
December	1st to 10th	Day	47% 5% 8% 18% 17% 4	1677
	11th to 20th	Day	44% 3 7% 19% 22% 4	1915
	21st to end	Day	47% 5% 11% 21% 13% 2	2783
January	1st to 10th	Night	43% 4 6% 21% 23% 2	4291
	11th to 20th	Night	42% 5% 8% 21% 20% 4	4120
	21st to end	Night	43% 3 8% 23% 20% 3	4532
February	1st to 10th	Night	48% 3 9% 17% 20% 3	2343
	11th to 20th	Night	45% 4 7% 21% 17% 6%	2219
	21st to end	Night	46% 4 8% 16% 20% 7%	1884
March	1st to 10th	Night	46% 5% 9% 14% 16% 10%	3711
	11th to 20th	Night	37% 6% 8% 22% 20% 8%	3480
	21st to end	Night	39% 5% 10% 22% 22% 2	3595
April	1st to 10th	Night	34% 6% 11% 23% 21% 5%	1900
	11th to 20th	Night	34% 5% 7% 22% 24% 7%	1875
	21st to end	Night	35% 6% 9% 24% 22% 3	1900
May	1st to 10th	Night	41% 7% 12% 22% 14% 3	3160
	11th to 20th	Night	37% 9% 14% 25% 14% 1	2919
	21st to end	Night	35% 11% 12% 26% 14% 2	2847
June	1st to 10th	Night	29% 10% 14% 22% 23% 2	1520
	11th to 20th	Night	18% 8% 15% 30% 25% 5%	1520
	21st to end	Night	20% 9% 16% 28% 21% 5%	1520
July	1st to 10th	Night	27% 7% 22% 27% 16% 2	2490
	11th to 20th	Night	27% 6% 13% 37% 15% 3	2672
	21st to end	Night	43% 6% 14% 25% 12% 1	2999
August	1st to 10th	Night	14% 5% 12% 40% 26% 2	3094
	11th to 20th	Night	24% 6% 20% 29% 19% 2	3130
	21st to end	Night	24% 5% 12% 26% 28% 4	3476
September	1st to 10th	Night	30% 7% 10% 23% 22% 9%	1900
	11th to 20th	Night	32% 6% 10% 19% 27% 6%	1932
	21st to end	Night	30% 3 9% 24% 25% 9%	2090
October	1st to 10th	Night	15% 3 6% 18% 30% 28%	3696
	11th to 20th	Night	17% 3 3 16% 35% 26%	3779
	21st to end	Night	26% 2 5% 26% 25% 15%	4120
November	1st to 10th	Night	30% 4 7% 22% 27% 9%	2390
	11th to 20th	Night	30% 4 8% 21% 26% 10%	2470
	21st to end	Night	36% 4 7% 21% 25% 6%	2470
December	1st to 10th	Night	42% 4 9% 22% 18% 5%	2498
	11th to 20th	Night	39% 4 7% 22% 23% 4	3281
	21st to end	Night	44% 7% 11% 18% 15% 4	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	23% 16% 39% 14% 7% 1	270
	11th to 20th	Day	30% 16% 35% 14% 4	270
	21st to end	Day	22% 18% 40% 16% 3 1	297
February	1st to 10th	Day	24% 16% 38% 13% 7% 1	270
	11th to 20th	Day	34% 19% 31% 13% 3	270
	21st to end	Day	40% 19% 28% 8% 5%	225
March	1st to 10th	Day	24% 16% 34% 20% 5% 1	270
	11th to 20th	Day	26% 20% 30% 23% 2	270
	21st to end	Day	22% 18% 33% 20% 7% 1	427
April	1st to 10th	Day	18% 16% 34% 23% 9% 1	460
	11th to 20th	Day	21% 14% 32% 23% 9% 2	452
	21st to end	Day	21% 10% 31% 22% 12% 3	460
May	1st to 10th	Day	17% 12% 27% 26% 15% 2	463
	11th to 20th	Day	13% 7% 24% 26% 22% 9%	487
	21st to end	Day	10% 6% 22% 31% 21% 10%	669
June	1st to 10th	Day	10% 4 16% 27% 28% 15%	680
	11th to 20th	Day	4 2 15% 35% 32% 12%	680
	21st to end	Day	5% 17% 38% 27% 13%	680
July	1st to 10th	Day	7% 2 10% 30% 29% 21%	671
	11th to 20th	Day	6% 2 13% 24% 36% 19%	668
	21st to end	Day	8% 2 10% 30% 33% 17%	739
August	1st to 10th	Day	6% 2 13% 28% 35% 16%	515
	11th to 20th	Day	11% 1 11% 31% 32% 14%	479
	21st to end	Day	12% 1 6% 20% 35% 26%	539
September	1st to 10th	Day	9% 1 10% 30% 33% 17%	490
	11th to 20th	Day	10% 2 14% 22% 33% 19%	490
	21st to end	Day	16% 3 15% 31% 23% 12%	490
October	1st to 10th	Day	8% 2 20% 35% 27% 8%	361
	11th to 20th	Day	12% 8% 32% 29% 14% 5%	300
	21st to end	Day	23% 10% 29% 25% 10% 4	330
November	1st to 10th	Day	18% 7% 23% 33% 16% 3	279
	11th to 20th	Day	8% 17% 35% 27% 12% 1	270
	21st to end	Day	25% 10% 31% 19% 13% 2	270
December	1st to 10th	Day	26% 19% 29% 20% 6% 1	270
	11th to 20th	Day	24% 14% 31% 21% 8% 1	270
	21st to end	Day	26% 16% 36% 16% 5% 1	297
January	1st to 10th	Night	23% 11% 35% 26% 5%	950
	11th to 20th	Night	24% 14% 34% 25% 3	950
	21st to end	Night	22% 11% 38% 27% 2	1045
February	1st to 10th	Night	26% 10% 34% 26% 4	823
	11th to 20th	Night	24% 14% 34% 25% 3	743
	21st to end	Night	25% 15% 35% 22% 3	628
March	1st to 10th	Night	19% 13% 33% 30% 5%	751
	11th to 20th	Night	22% 11% 35% 27% 5% 1	570
	21st to end	Night	19% 10% 33% 28% 11%	627
April	1st to 10th	Night	14% 11% 37% 29% 9%	570
	11th to 20th	Night	16% 9% 33% 29% 12% 1	563
	21st to end	Night	14% 8% 35% 33% 9% 2	570
May	1st to 10th	Night	15% 6% 26% 37% 14% 2	570
	11th to 20th	Night	14% 6% 22% 37% 18% 3	561
	21st to end	Night	5% 3 19% 39% 28% 5%	617
June	1st to 10th	Night	8% 2 15% 36% 32% 7%	570
	11th to 20th	Night	2 1 11% 39% 44% 2	570
	21st to end	Night	5% 1 12% 38% 39% 6%	570
July	1st to 10th	Night	3 1 10% 32% 44% 10%	555
	11th to 20th	Night	6% 1 10% 27% 43% 12%	552
	21st to end	Night	6% 1 6% 33% 42% 11%	624
August	1st to 10th	Night	4 1 5% 32% 48% 9%	567
	11th to 20th	Night	6% 2 8% 35% 43% 6%	564
	21st to end	Night	6% 1 8% 28% 48% 9%	627
September	1st to 10th	Night	9% 2 8% 35% 42% 4	570
	11th to 20th	Night	12% 1 12% 31% 37% 7%	602
	21st to end	Night	11% 4 15% 33% 33% 4	760
October	1st to 10th	Night	7% 4 18% 34% 33% 4	760
	11th to 20th	Night	13% 6% 24% 37% 18% 2	760
	21st to end	Night	18% 7% 25% 34% 15% 1	836
November	1st to 10th	Night	12% 5% 26% 36% 19% 2	755
	11th to 20th	Night	13% 7% 32% 36% 11%	760
	21st to end	Night	16% 10% 31% 29% 12% 1	760
December	1st to 10th	Night	21% 10% 32% 30% 7%	788
	11th to 20th	Night	23% 9% 28% 33% 7%	950
	21st to end	Night	24% 13% 31% 28% 4	1045

Page generated at 2024-11-01 21:47:41. Version ac07

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