Collierville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Collierville clear sky chart from 2005-11-05 to 2017-10-31.

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
48%
15776
25%
47388
18%
15731
55%
15731
31%
28375

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
27%
900
25%
2410
9%
895
39%
895
25%
1589
January16th to endNight
25%
960
24%
2496
9%
960
35%
960
27%
1669
February1st to 15thNight
24%
719
19%
2127
7%
716
33%
716
24%
1381
February16th to endNight
25%
631
25%
1893
10%
631
37%
631
24%
1191
March1st to 15thNight
29%
675
19%
2115
11%
675
36%
675
22%
1365
March16th to endNight
38%
576
22%
2016
15%
576
49%
576
26%
1197
April1st to 15thNight
36%
539
24%
1797
16%
539
48%
539
29%
1033
April16th to endNight
42%
540
25%
1800
18%
540
55%
540
32%
1007
May1st to 15thNight
50%
540
20%
1761
18%
540
56%
540
28%
1071
May16th to endNight
61%
562
23%
1620
20%
561
64%
561
34%
985
June1st to 15thNight
73%
540
25%
1440
20%
540
75%
540
45%
826
June16th to endNight
79%
540
26%
1440
21%
540
81%
540
48%
807
July1st to 15thNight
73%
510
20%
1360
18%
510
75%
510
39%
816
July16th to endNight
82%
564
23%
1589
24%
531
83%
531
42%
875
August1st to 15thNight
82%
539
22%
1788
26%
536
83%
536
38%
958
August16th to endNight
74%
573
24%
1910
27%
573
76%
573
34%
1072
September1st to 15thNight
68%
540
23%
1800
26%
540
70%
540
31%
1055
September16th to endNight
64%
690
33%
1953
27%
690
68%
690
40%
1110
October1st to 15thNight
61%
720
32%
2094
26%
720
65%
720
41%
1155
October16th to endNight
51%
768
35%
2304
26%
768
61%
768
39%
1270
November1st to 15thNight
50%
700
31%
2257
25%
700
60%
700
35%
1236
November16th to endNight
37%
720
26%
2340
18%
720
48%
720
28%
1389
December1st to 15thNight
34%
770
23%
2390
13%
770
45%
770
24%
1506
December16th to endNight
28%
960
20%
2688
10%
960
37%
960
24%
1812

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%3445%7%43%
48358
Night
11%5%2442345%7%49%
47576
TransparencyDay
39%6%10%21%17%3
48050
Night
34%5%10%22%21%5%
47389
SeeingDay
12%5%17%25%24%13%
5814
Night
14%7%23%30%19%3
15777

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%7%23323335%44%
1525
16th to endDay
16%7%35%433335%44%
1728
February1st to 15thDay
16%7%37%42333441%
1734
16th to endDay
16%8%45%42445%5%39%
1580
March1st to 15thDay
19%8%47%5%24335%36%
1854
16th to endDay
14%6%37%5%34447%37%
2206
April1st to 15thDay
12%5%25%4245%5%5%46%
2151
16th to endDay
13%5%25%5%245%6%6%41%
2160
May1st to 15thDay
14%5%26%5%35%5%46%39%
2187
16th to endDay
8%5%26%6%35%5%6%9%39%
2491
June1st to 15thDay
5%315%5%45%6%7%9%44%
2520
16th to endDay
43245%46%6%6%11%44%
2520
July1st to 15thDay
8%435%6%47%7%7%10%35%
2520
16th to endDay
6%3246%47%6%7%10%39%
2469
August1st to 15thDay
6%325%5%36%6%8%10%41%
2160
16th to endDay
9%5%246%36%6%8%9%38%
2292
September1st to 15thDay
10%5%25%5%45%5%6%8%39%
2160
16th to endDay
8%5%24423447%51%
1995
October1st to 15thDay
8%4245%2445%5%52%
1863
16th to endDay
15%31231133360%
1919
November1st to 15thDay
13%6%13212236%56%
1600
16th to endDay
18%5%23423435%47%
1620
December1st to 15thDay
19%6%45%424445%38%
1568
16th to endDay
17%9%34424345%39%
1536
January1st to 15thNight
16%8%3432323446%
2410
16th to endNight
17%6%34423335%45%
2496
February1st to 15thNight
17%7%36%5%13335%44%
2118
16th to endNight
13%6%35%434336%45%
1893
March1st to 15thNight
16%6%34434345%43%
2115
16th to endNight
14%5%25%41335%6%45%
2016
April1st to 15thNight
12%42342345%8%48%
1797
16th to endNight
10%5%2432335%7%51%
1800
May1st to 15thNight
14%5%2432345%7%47%
1760
16th to endNight
5%5%245%345%7%9%45%
1619
June1st to 15thNight
4315%32346%10%54%
1440
16th to endNight
2233335%7%12%55%
1440
July1st to 15thNight
33245%246%6%11%47%
1440
16th to endNight
42123245%6%13%53%
1696
August1st to 15thNight
42133246%8%12%50%
1800
16th to endNight
5%4244346%7%10%47%
1910
September1st to 15thNight
9%4244245%5%7%48%
1800
16th to endNight
7%42442335%6%55%
1953
October1st to 15thNight
8%413423448%56%
2094
16th to endNight
12%41321224459%
2304
November1st to 15thNight
10%323422346%56%
2257
16th to endNight
14%5%24323435%49%
2340
December1st to 15thNight
17%8%24312345%44%
2390
16th to endNight
18%9%34323346%40%
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
44%37%22%18%4
1526
16th to endDay
43%39%21%20%2
1728
February1st to 15thDay
45%47%22%16%3
1736
16th to endDay
46%38%19%18%3
1580
March1st to 15thDay
51%47%16%13%5%
1854
16th to endDay
45%6%10%22%14%
2208
April1st to 15thDay
39%5%8%23%19%4
2151
16th to endDay
40%6%9%22%19%1
2160
May1st to 15thDay
45%6%9%17%18%2
2187
16th to endDay
39%8%16%23%10%2
2495
June1st to 15thDay
33%8%11%25%19%1
2520
16th to endDay
31%8%14%24%18%3
2520
July1st to 15thDay
39%9%16%19%11%4
2371
16th to endDay
36%9%16%24%11%2
2313
August1st to 15thDay
33%9%15%22%14%3
2148
16th to endDay
36%8%13%24%13%2
2292
September1st to 15thDay
40%7%10%20%14%5%
2160
16th to endDay
32%5%10%22%23%6%
1995
October1st to 15thDay
32%49%22%22%7%
1863
16th to endDay
29%3322%32%8%
1919
November1st to 15thDay
30%37%21%28%9%
1600
16th to endDay
39%38%20%23%4
1620
December1st to 15thDay
47%48%20%15%4
1568
16th to endDay
46%49%19%15%3
1536
January1st to 15thNight
41%46%20%23%4
2410
16th to endNight
43%36%21%20%5%
2496
February1st to 15thNight
43%29%21%18%3
2127
16th to endNight
41%37%22%19%5%
1893
March1st to 15thNight
43%49%18%17%7%
2115
16th to endNight
38%411%24%19%1
2016
April1st to 15thNight
34%410%23%20%5%
1797
16th to endNight
31%410%25%23%4
1800
May1st to 15thNight
36%6%11%22%19%3
1761
16th to endNight
32%7%15%23%16%3
1621
June1st to 15thNight
24%6%14%27%23%2
1440
16th to endNight
22%7%16%24%26%3
1440
July1st to 15thNight
28%7%16%28%13%5%
1360
16th to endNight
22%9%20%28%17%2
1589
August1st to 15thNight
23%9%18%26%19%3
1788
16th to endNight
29%7%16%25%16%4
1910
September1st to 15thNight
33%7%12%21%18%7%
1800
16th to endNight
29%49%24%23%8%
1953
October1st to 15thNight
27%49%23%23%11%
2094
16th to endNight
30%25%19%31%10%
2304
November1st to 15thNight
29%46%22%27%10%
2257
16th to endNight
37%37%18%25%7%
2340
December1st to 15thNight
41%39%22%17%6%
2390
16th to endNight
45%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
25%15%33%15%7%2
90
16th to endDay
20%25%39%10%31
96
February1st to 15thDay
14%22%37%16%7%1
90
16th to endDay
22%18%37%14%7%
81
March1st to 15thDay
26%15%36%17%3
90
16th to endDay
13%15%28%30%11%
192
April1st to 15thDay
18%14%28%23%12%2
270
16th to endDay
16%8%25%29%16%3
270
May1st to 15thDay
20%8%21%30%12%6%
288
16th to endDay
11%421%28%23%10%
391
June1st to 15thDay
6%116%26%27%20%
495
16th to endDay
4214%31%32%15%
495
July1st to 15thDay
6%111%31%34%14%
475
16th to endDay
6%16%22%35%27%
509
August1st to 15thDay
8%1225%36%24%
313
16th to endDay
16%323%33%22%
332
September1st to 15thDay
13%29%20%31%22%
315
16th to endDay
11%211%24%30%19%
314
October1st to 15thDay
10%324%29%24%7%
198
16th to endDay
15%6%27%28%17%4
144
November1st to 15thDay
12%8%18%37%21%1
90
16th to endDay
25%11%31%18%10%3
90
December1st to 15thDay
26%11%33%12%11%5%
90
16th to endDay
16%21%36%19%5%
96
January1st to 15thNight
20%16%32%24%6%
900
16th to endNight
19%11%39%27%1
960
February1st to 15thNight
21%13%37%23%4
719
16th to endNight
19%17%36%24%2
631
March1st to 15thNight
21%12%32%29%4
675
16th to endNight
16%9%31%29%11%1
576
April1st to 15thNight
14%10%35%28%10%1
539
16th to endNight
11%9%31%33%12%1
540
May1st to 15thNight
16%7%21%36%14%2
540
16th to endNight
7%218%42%24%4
563
June1st to 15thNight
5%111%37%37%5%
540
16th to endNight
311%33%45%5%
540
July1st to 15thNight
49%33%42%8%
510
16th to endNight
36%26%47%15%
564
August1st to 15thNight
5%329%49%11%
539
16th to endNight
7%8%30%44%8%
573
September1st to 15thNight
11%19%32%36%8%
540
16th to endNight
8%413%32%34%6%
690
October1st to 15thNight
11%417%34%26%5%
720
16th to endNight
15%5%22%32%21%2
768
November1st to 15thNight
12%8%25%33%19%1
700
16th to endNight
18%10%30%26%12%1
720
December1st to 15thNight
23%12%27%29%7%
770
16th to endNight
23%12%32%26%5%
960
Page generated at 2017-11-01 16:23:38. Version ac04

Copyright 2017 A. Danko


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