Memphis
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Memphis clear sky chart from 2005-11-05 to 2018-02-22.

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 TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(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

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
50%
16309
25%
48889
18%
16264
56%
16264
32%
29281

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
30%
975
24%
2592
10%
970
40%
970
28%
1693
January16th to endNight
30%
1040
25%
2704
10%
1040
40%
1040
30%
1781
February1st to 15thNight
26%
807
19%
2335
8%
804
34%
804
24%
1543
February16th to endNight
28%
659
24%
1977
10%
659
38%
659
25%
1248
March1st to 15thNight
31%
654
19%
2094
11%
654
38%
654
23%
1348
March16th to endNight
40%
576
21%
2028
17%
576
47%
576
26%
1221
April1st to 15thNight
39%
539
25%
1797
18%
539
51%
539
30%
1033
April16th to endNight
44%
540
26%
1800
20%
540
56%
540
32%
1014
May1st to 15thNight
50%
540
20%
1782
17%
540
57%
540
28%
1079
May16th to endNight
61%
562
23%
1590
19%
561
65%
561
33%
984
June1st to 15thNight
76%
540
26%
1440
22%
540
78%
540
46%
804
June16th to endNight
78%
540
26%
1440
22%
540
80%
540
47%
817
July1st to 15thNight
74%
510
20%
1371
17%
510
76%
510
41%
817
July16th to endNight
82%
564
23%
1594
26%
531
83%
531
41%
879
August1st to 15thNight
82%
539
22%
1772
27%
536
84%
536
39%
927
August16th to endNight
76%
573
25%
1910
30%
573
76%
573
33%
1072
September1st to 15thNight
68%
540
25%
1800
27%
540
70%
540
31%
1038
September16th to endNight
67%
678
33%
1941
28%
678
70%
678
42%
1090
October1st to 15thNight
61%
720
32%
2119
27%
720
66%
720
41%
1170
October16th to endNight
54%
768
35%
2304
26%
768
63%
768
40%
1265
November1st to 15thNight
51%
760
30%
2432
25%
760
59%
760
34%
1355
November16th to endNight
43%
780
28%
2535
21%
780
54%
780
30%
1479
December1st to 15thNight
37%
865
23%
2620
14%
865
47%
865
27%
1652
December16th to endNight
31%
1040
20%
2912
11%
1040
39%
1040
25%
1972

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 ForecastData
Points
Cloud CoverDay
12%5%25%5%2445%7%43%
49356
Night
11%5%24423447%49%
49077
TransparencyDay
39%6%11%22%17%3
49048
Night
34%5%10%22%21%5%
48890
SeeingDay
13%418%25%24%13%
6170
Night
14%6%24%31%20%3
16310

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
20%6%33413335%43%
1672
16th to endDay
16%6%25%423335%45%
1872
February1st to 15thDay
17%6%36%423336%41%
1855
16th to endDay
19%8%35%423445%37%
1643
March1st to 15thDay
20%8%36%5%2443436%
1875
16th to endDay
14%8%25%5%3446%6%36%
2192
April1st to 15thDay
13%425%5%3435%6%45%
2151
16th to endDay
13%6%35%5%2445%7%41%
2160
May1st to 15thDay
14%6%346%35%45%6%40%
2169
16th to endDay
8%5%35%6%35%6%6%8%39%
2521
June1st to 15thDay
4425%5%36%6%7%9%44%
2520
16th to endDay
4325%5%36%6%6%10%46%
2520
July1st to 15thDay
7%5%36%6%46%7%8%10%34%
2505
16th to endDay
6%325%5%46%7%7%9%41%
2466
August1st to 15thDay
6%315%5%36%6%7%10%43%
2178
16th to endDay
9%424436%6%7%10%39%
2292
September1st to 15thDay
10%425%5%35%6%5%8%40%
2160
16th to endDay
10%5%14423347%52%
2007
October1st to 15thDay
9%42442435%6%51%
1839
16th to endDay
15%41111223459%
1920
November1st to 15thDay
14%6%2331323454%
1753
16th to endDay
16%5%24423335%48%
1755
December1st to 15thDay
19%7%25%414335%40%
1667
16th to endDay
19%9%25%423335%38%
1664
January1st to 15thNight
18%6%2432323447%
2592
16th to endNight
16%6%25%32334447%
2704
February1st to 15thNight
18%6%34423335%43%
2326
16th to endNight
14%6%35%324345%45%
1977
March1st to 15thNight
16%6%25%423345%44%
2094
16th to endNight
15%5%24423446%45%
2028
April1st to 15thNight
11%42342335%7%49%
1797
16th to endNight
10%414424347%51%
1800
May1st to 15thNight
13%6%14324447%46%
1781
16th to endNight
45%25%5%45%5%6%8%45%
1589
June1st to 15thNight
421332446%12%53%
1440
16th to endNight
12124246%7%10%55%
1440
July1st to 15thNight
33135%35%5%6%12%47%
1452
16th to endNight
421232446%12%53%
1702
August1st to 15thNight
3212325%5%7%10%53%
1782
16th to endNight
5%325%335%5%7%11%46%
1910
September1st to 15thNight
9%425%3245%48%49%
1800
16th to endNight
8%424323336%56%
1941
October1st to 15thNight
7%415%22345%8%55%
2119
16th to endNight
13%31321233460%
2304
November1st to 15thNight
11%313323346%53%
2432
16th to endNight
14%424223445%51%
2535
December1st to 15thNight
16%7%24422345%46%
2620
16th to endNight
19%8%24423445%40%
2912

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
43%46%23%16%3
1673
16th to endDay
42%29%21%19%3
1872
February1st to 15thDay
45%48%23%14%2
1857
16th to endDay
48%48%17%17%2
1643
March1st to 15thDay
50%47%18%13%4
1875
16th to endDay
46%5%11%23%12%
2194
April1st to 15thDay
38%5%9%23%19%3
2151
16th to endDay
41%5%8%23%18%1
2160
May1st to 15thDay
44%8%10%17%17%2
2169
16th to endDay
40%8%15%22%10%2
2525
June1st to 15thDay
32%8%12%25%19%1
2520
16th to endDay
31%8%13%24%19%3
2520
July1st to 15thDay
38%11%15%20%10%4
2357
16th to endDay
33%10%17%24%12%2
2311
August1st to 15thDay
32%9%17%21%15%3
2164
16th to endDay
36%8%14%23%13%3
2292
September1st to 15thDay
38%8%11%20%14%6%
2160
16th to endDay
31%410%21%24%6%
2007
October1st to 15thDay
33%410%22%20%9%
1839
16th to endDay
28%3423%31%8%
1920
November1st to 15thDay
34%36%21%25%8%
1753
16th to endDay
39%38%20%23%4
1755
December1st to 15thDay
46%49%20%15%4
1667
16th to endDay
48%311%17%14%3
1664
January1st to 15thNight
41%37%20%22%3
2592
16th to endNight
40%36%22%21%4
2704
February1st to 15thNight
44%39%21%17%3
2335
16th to endNight
40%48%21%19%5%
1977
March1st to 15thNight
42%5%9%16%18%7%
2094
16th to endNight
39%411%23%18%1
2028
April1st to 15thNight
33%49%23%21%6%
1797
16th to endNight
31%5%10%24%24%3
1800
May1st to 15thNight
37%5%12%21%19%4
1782
16th to endNight
34%6%15%23%16%3
1591
June1st to 15thNight
22%7%15%28%24%2
1440
16th to endNight
21%8%15%24%25%4
1440
July1st to 15thNight
26%8%17%27%14%4
1371
16th to endNight
22%9%19%29%15%2
1594
August1st to 15thNight
22%9%18%26%20%2
1772
16th to endNight
29%8%14%25%17%5%
1910
September1st to 15thNight
32%7%10%22%19%8%
1800
16th to endNight
28%310%24%24%8%
1941
October1st to 15thNight
26%5%8%24%23%11%
2119
16th to endNight
29%25%19%31%11%
2304
November1st to 15thNight
31%37%22%25%9%
2432
16th to endNight
35%47%19%27%7%
2535
December1st to 15thNight
40%39%23%16%6%
2620
16th to endNight
45%410%19%17%3
2912

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
25%9%37%16%8%1
135
16th to endDay
16%18%40%16%5%2
144
February1st to 15thDay
20%14%38%17%7%1
135
16th to endDay
29%9%36%17%9%
100
March1st to 15thDay
30%14%30%23%2
90
16th to endDay
12%15%27%33%11%
178
April1st to 15thDay
17%10%32%25%11%2
270
16th to endDay
21%5%24%29%15%4
270
May1st to 15thDay
19%8%22%26%17%5%
288
16th to endDay
12%423%25%22%10%
421
June1st to 15thDay
5%13%30%28%21%
495
16th to endDay
4114%32%30%15%
495
July1st to 15thDay
7%111%32%29%18%
475
16th to endDay
46%21%37%29%
515
August1st to 15thDay
8%6%20%40%23%
331
16th to endDay
16%419%36%22%
332
September1st to 15thDay
11%8%19%33%26%
315
16th to endDay
10%10%23%33%20%
314
October1st to 15thDay
9%317%37%23%8%
174
16th to endDay
13%227%32%14%9%
144
November1st to 15thDay
20%5%17%31%18%5%
135
16th to endDay
18%7%30%22%17%4
135
December1st to 15thDay
23%6%37%19%9%2
135
16th to endDay
29%13%36%17%4
144
January1st to 15thNight
21%11%33%27%5%
975
16th to endNight
20%9%37%29%3
1040
February1st to 15thNight
22%10%37%25%4
807
16th to endNight
18%13%37%26%4
659
March1st to 15thNight
20%10%34%29%4
654
16th to endNight
17%7%29%31%12%1
576
April1st to 15thNight
12%10%34%30%10%
539
16th to endNight
11%6%33%34%12%1
540
May1st to 15thNight
17%423%37%15%2
540
16th to endNight
6%219%38%28%4
563
June1st to 15thNight
5%11%35%41%5%
540
16th to endNight
210%33%47%4
540
July1st to 15thNight
410%31%43%9%
510
16th to endNight
4427%46%15%
564
August1st to 15thNight
4328%51%10%
539
16th to endNight
6%6%28%48%9%
573
September1st to 15thNight
11%18%30%39%7%
540
16th to endNight
10%212%30%37%6%
678
October1st to 15thNight
9%318%33%29%5%
720
16th to endNight
14%5%21%36%20%1
768
November1st to 15thNight
12%6%25%34%20%1
760
16th to endNight
16%7%29%30%15%1
780
December1st to 15thNight
19%8%29%33%8%
865
16th to endNight
23%10%30%30%4
1040
Page generated at 2018-02-23 10:21:37. Version ac04

Copyright 2018 A. Danko


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