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 2017-08-12.

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 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%
15510
25%
46522
18%
15465
56%
15465
32%
27852

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
29%
900
25%
2392
10%
895
40%
895
28%
1564
January16th to endNight
28%
960
25%
2496
9%
960
38%
960
29%
1660
February1st to 15thNight
26%
744
19%
2152
8%
741
35%
741
25%
1409
February16th to endNight
28%
631
25%
1893
10%
631
39%
631
26%
1180
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%
527
23%
1734
28%
524
83%
524
40%
895
August16th to endNight
76%
525
24%
1750
29%
525
77%
525
34%
971
September1st to 15thNight
68%
495
26%
1650
28%
495
70%
495
30%
963
September16th to endNight
64%
621
31%
1779
25%
621
67%
621
40%
1020
October1st to 15thNight
61%
660
33%
1942
28%
660
65%
660
41%
1074
October16th to endNight
55%
704
33%
2112
25%
704
63%
704
39%
1172
November1st to 15thNight
52%
700
31%
2240
25%
700
60%
700
36%
1218
November16th to endNight
41%
720
26%
2340
19%
720
51%
720
29%
1395
December1st to 15thNight
36%
798
22%
2418
13%
798
46%
798
27%
1537
December16th to endNight
31%
960
20%
2688
11%
960
39%
960
25%
1798

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%43445%7%43%
47444
Night
11%5%24423447%49%
46710
TransparencyDay
39%6%11%21%17%3
47136
Night
34%5%10%22%21%5%
46523
SeeingDay
12%418%25%24%14%
5534
Night
14%6%24%31%20%3
15511

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
21%6%33313335%44%
1543
16th to endDay
16%7%36%5%23335%44%
1728
February1st to 15thDay
16%7%36%423326%42%
1708
16th to endDay
18%8%35%423345%38%
1580
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%436%6%7%10%43%
2130
16th to endDay
8%423436%7%7%10%40%
2100
September1st to 15thDay
10%5%25%5%46%6%6%8%39%
1980
16th to endDay
11%5%14323347%51%
1840
October1st to 15thDay
9%424424346%52%
1686
16th to endDay
15%41111223459%
1760
November1st to 15thDay
13%5%23313235%56%
1615
16th to endDay
17%5%24413335%48%
1620
December1st to 15thDay
20%7%25%424435%39%
1539
16th to endDay
19%8%24424335%39%
1536
January1st to 15thNight
18%6%2432323448%
2392
16th to endNight
16%6%25%32334445%
2496
February1st to 15thNight
17%6%35%423235%44%
2143
16th to endNight
14%6%35%324335%46%
1893
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%54%
1744
16th to endNight
4325%335%6%7%12%46%
1750
September1st to 15thNight
8%425%4245%5%8%48%
1650
16th to endNight
9%424323337%54%
1779
October1st to 15thNight
7%414223449%55%
1942
16th to endNight
13%31321233459%
2112
November1st to 15thNight
10%413323346%54%
2240
16th to endNight
15%5%24323445%49%
2340
December1st to 15thNight
17%7%24422345%45%
2418
16th to endNight
19%8%24423335%42%
2688

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
42%47%24%17%4
1544
16th to endDay
44%310%22%18%2
1728
February1st to 15thDay
45%49%22%15%2
1710
16th to endDay
47%48%18%18%2
1580
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
31%9%18%22%15%3
2116
16th to endDay
34%8%15%24%13%3
2100
September1st to 15thDay
40%9%11%18%14%6%
1980
16th to endDay
32%49%20%25%7%
1840
October1st to 15thDay
32%49%21%22%9%
1686
16th to endDay
29%3422%31%8%
1760
November1st to 15thDay
32%36%22%26%8%
1615
16th to endDay
40%38%20%22%4
1620
December1st to 15thDay
47%49%20%14%4
1539
16th to endDay
47%411%17%15%3
1536
January1st to 15thNight
41%36%20%23%4
2392
16th to endNight
42%37%22%20%4
2496
February1st to 15thNight
44%39%21%17%3
2152
16th to endNight
40%38%22%19%5%
1893
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
21%8%18%27%20%2
1734
16th to endNight
28%8%15%25%18%5%
1750
September1st to 15thNight
32%7%10%21%18%9%
1650
16th to endNight
30%39%21%25%9%
1779
October1st to 15thNight
26%5%8%22%24%12%
1942
16th to endNight
30%26%19%30%11%
2112
November1st to 15thNight
30%37%22%26%10%
2240
16th to endNight
37%47%19%25%6%
2340
December1st to 15thNight
41%39%22%16%6%
2418
16th to endNight
44%310%19%18%3
2688

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
26%13%35%13%8%2
90
16th to endDay
18%16%45%14%31
96
February1st to 15thDay
16%18%38%18%42
90
16th to endDay
25%9%35%17%11%
81
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
7%6%20%40%24%
315
16th to endDay
14%5%16%37%25%
268
September1st to 15thDay
10%7%19%36%25%
255
16th to endDay
12%12%25%33%15%
254
October1st to 15thDay
8%320%36%23%7%
126
16th to endDay
15%321%32%17%9%
96
November1st to 15thDay
15%5%15%35%21%6%
90
16th to endDay
26%7%32%17%13%2
90
December1st to 15thDay
28%5%32%20%8%4
90
16th to endDay
21%14%39%19%4
96
January1st to 15thNight
21%12%33%26%6%
900
16th to endNight
20%9%38%28%2
960
February1st to 15thNight
22%9%37%26%3
744
16th to endNight
17%13%37%26%4
631
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
4327%52%11%
527
16th to endNight
6%6%28%48%9%
525
September1st to 15thNight
10%19%31%40%7%
495
16th to endNight
11%213%31%36%4
621
October1st to 15thNight
10%318%32%29%5%
660
16th to endNight
14%5%20%36%20%1
704
November1st to 15thNight
12%6%25%33%20%1
700
16th to endNight
17%8%30%29%14%1
720
December1st to 15thNight
20%8%30%32%8%
798
16th to endNight
22%11%30%30%5%
960
Page generated at 2017-08-13 13:16:46. Version ac04

Copyright 2017 A. Danko


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