Tall Timbers
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tall Timbers clear sky chart from 2005-11-05 to 2017-10-06.

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
44%
15392
21%
47105
13%
15356
53%
15356
26%
29568

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%
716
22%
2419
9%
716
43%
716
20%
1521
January16th to endNight
26%
768
22%
2496
10%
768
42%
768
22%
1555
February1st to 15thNight
27%
701
21%
2278
9%
701
43%
701
24%
1378
February16th to endNight
25%
631
26%
1893
10%
631
44%
631
26%
1171
March1st to 15thNight
34%
720
22%
2025
11%
720
46%
720
28%
1287
March16th to endNight
36%
768
22%
2070
11%
768
45%
768
27%
1387
April1st to 15thNight
39%
718
20%
1796
7%
718
46%
718
32%
1187
April16th to endNight
49%
720
20%
1800
10%
720
51%
720
32%
1179
May1st to 15thNight
42%
606
16%
1686
10%
606
46%
606
25%
1150
May16th to endNight
60%
374
18%
1497
19%
374
64%
374
23%
877
June1st to 15thNight
63%
360
18%
1440
21%
360
68%
360
25%
835
June16th to endNight
64%
360
16%
1440
18%
360
67%
360
22%
855
July1st to 15thNight
65%
340
13%
1360
17%
340
66%
340
21%
835
July16th to endNight
70%
545
17%
1576
15%
512
74%
512
32%
956
August1st to 15thNight
67%
568
16%
1638
11%
565
68%
565
29%
1059
August16th to endNight
67%
764
18%
1910
12%
764
67%
764
32%
1284
September1st to 15thNight
63%
720
24%
1800
16%
720
65%
720
34%
1179
September16th to endNight
55%
717
22%
1959
17%
717
58%
717
27%
1297
October1st to 15thNight
50%
684
24%
2051
22%
684
56%
684
27%
1298
October16th to endNight
40%
704
29%
2112
19%
704
54%
704
30%
1253
November1st to 15thNight
40%
700
24%
2233
14%
700
53%
700
27%
1342
November16th to endNight
38%
720
23%
2418
16%
720
50%
720
23%
1463
December1st to 15thNight
30%
720
20%
2520
11%
720
44%
720
20%
1575
December16th to endNight
27%
768
23%
2688
11%
768
43%
768
21%
1645

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%2442445%8%44%
48076
Night
13%5%2442445%7%44%
47287
Cloud CoverDay
12%42442445%8%44%
48086
Night
14%5%2442445%7%44%
47291
TransparencyDay
36%6%12%24%17%3
47776
Night
38%5%10%23%17%3
47105
SeeingDay
15%418%28%23%9%
5834
Night
16%6%25%31%17%2
15400

By Month

Percentage Cloud Cover NE (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
15%5%35%424447%42%
1516
16th to endDay
15%7%34424347%42%
1728
February1st to 15thDay
14%6%3443445%6%42%
1582
16th to endDay
14%5%24435%5%5%7%42%
1580
March1st to 15thDay
16%5%24413446%45%
1921
16th to endDay
18%5%24324346%43%
2152
April1st to 15thDay
12%5%2332445%6%49%
2152
16th to endDay
13%5%25%42335%6%46%
2160
May1st to 15thDay
13%5%2442445%7%43%
2273
16th to endDay
12%4143235%7%9%44%
2618
June1st to 15thDay
10%413335%5%6%10%45%
2520
16th to endDay
6%324435%5%7%11%43%
2520
July1st to 15thDay
8%4245%25%5%7%10%42%
2520
16th to endDay
5%325%5%36%6%8%12%40%
2482
August1st to 15thDay
9%6%35%5%3446%9%41%
2298
16th to endDay
10%415%436%46%10%43%
2292
September1st to 15thDay
11%5%2442435%8%46%
2160
16th to endDay
15%7%35%5%2345%6%40%
1998
October1st to 15thDay
15%415%423345%48%
1707
16th to endDay
13%5%14423446%50%
1760
November1st to 15thDay
16%423324345%48%
1622
16th to endDay
14%5%25%31335%5%49%
1539
December1st to 15thDay
14%6%2432445%6%44%
1440
16th to endDay
19%5%25%424335%42%
1536
January1st to 15thNight
15%5%235%245%47%43%
2419
16th to endNight
17%7%24324345%44%
2496
February1st to 15thNight
15%6%24324345%46%
2276
16th to endNight
13%7%23413446%46%
1893
March1st to 15thNight
14%5%2442345%6%46%
2013
16th to endNight
17%6%34414346%43%
2070
April1st to 15thNight
13%6%245%24447%45%
1796
16th to endNight
16%42332345%7%46%
1800
May1st to 15thNight
14%6%26%43446%8%38%
1686
16th to endNight
11%4144345%6%9%44%
1495
June1st to 15thNight
10%42433446%11%42%
1440
16th to endNight
7%5%25%6%46%5%6%8%42%
1440
July1st to 15thNight
7%425%7%35%5%7%9%40%
1440
16th to endNight
5%3245%37%5%6%10%43%
1683
August1st to 15thNight
7%5%26%435%6%7%8%42%
1649
16th to endNight
10%5%25%5%3446%9%42%
1910
September1st to 15thNight
12%415%5%235%47%47%
1800
16th to endNight
15%6%25%42345%7%41%
1959
October1st to 15thNight
15%5%24423336%46%
2051
16th to endNight
15%413423436%50%
2112
November1st to 15thNight
14%5%25%32333451%
2233
16th to endNight
14%5%1442445%7%45%
2418
December1st to 15thNight
16%6%2442445%6%42%
2520
16th to endNight
16%7%245%23346%43%
2688

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
15%6%24325%45%6%42%
1516
16th to endDay
16%6%2441435%6%43%
1728
February1st to 15thDay
14%6%24424446%42%
1582
16th to endDay
14%5%24436%5%5%7%42%
1580
March1st to 15thDay
16%42341335%7%46%
1932
16th to endDay
18%5%23424446%43%
2151
April1st to 15thDay
11%41342345%7%50%
2152
16th to endDay
14%5%25%423446%46%
2160
May1st to 15thDay
13%5%245%2445%8%42%
2273
16th to endDay
12%3244245%6%10%44%
2618
June1st to 15thDay
10%3134245%6%11%46%
2520
16th to endDay
6%3245%35%5%8%10%44%
2520
July1st to 15thDay
8%4245%35%47%11%43%
2520
16th to endDay
5%2146%36%7%8%11%41%
2482
August1st to 15thDay
9%5%25%5%35%5%6%9%41%
2298
16th to endDay
10%3245%345%6%9%44%
2292
September1st to 15thDay
11%42443345%8%45%
2160
16th to endDay
15%7%35%5%2435%6%40%
1998
October1st to 15thDay
15%424423446%47%
1707
16th to endDay
13%424323346%50%
1760
November1st to 15thDay
16%414324345%49%
1622
16th to endDay
13%425%323346%50%
1539
December1st to 15thDay
14%6%2442345%6%45%
1440
16th to endDay
18%5%35%424345%42%
1536
January1st to 15thNight
15%5%25%42445%7%41%
2419
16th to endNight
17%6%3432444444%
2496
February1st to 15thNight
15%6%34324345%46%
2269
16th to endNight
13%6%2443335%6%46%
1893
March1st to 15thNight
15%5%2442445%6%46%
2025
16th to endNight
17%6%24423346%42%
2070
April1st to 15thNight
13%5%25%424347%46%
1796
16th to endNight
17%42232335%7%46%
1800
May1st to 15thNight
15%6%25%435%45%8%38%
1685
16th to endNight
11%425%4345%5%9%44%
1495
June1st to 15thNight
11%424425%46%11%43%
1440
16th to endNight
7%425%6%46%5%7%8%42%
1440
July1st to 15thNight
8%416%8%35%5%7%9%40%
1440
16th to endNight
5%3345%36%5%7%10%42%
1683
August1st to 15thNight
7%5%25%5%35%6%6%10%40%
1649
16th to endNight
10%5%25%5%25%47%8%42%
1910
September1st to 15thNight
12%425%424347%46%
1800
16th to endNight
15%6%2442445%7%40%
1959
October1st to 15thNight
16%5%24423436%45%
2051
16th to endNight
15%323322346%50%
2112
November1st to 15thNight
15%5%24313335%50%
2233
16th to endNight
14%5%14325%45%6%45%
2418
December1st to 15thNight
16%6%2443345%6%42%
2520
16th to endNight
16%7%34423346%43%
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
41%5%12%22%14%3
1517
16th to endDay
41%310%23%17%3
1728
February1st to 15thDay
41%310%26%15%3
1584
16th to endDay
39%5%12%23%17%1
1580
March1st to 15thDay
37%5%12%24%15%4
1932
16th to endDay
40%5%10%21%17%3
2152
April1st to 15thDay
33%410%27%18%5%
2152
16th to endDay
37%410%20%18%8%
2160
May1st to 15thDay
38%7%14%22%15%1
2273
16th to endDay
33%8%15%26%14%1
2622
June1st to 15thDay
30%8%16%27%14%1
2520
16th to endDay
31%9%16%23%16%2
2520
July1st to 15thDay
34%9%14%22%16%2
2371
16th to endDay
30%10%16%24%16%1
2326
August1st to 15thDay
36%7%13%24%15%1
2285
16th to endDay
34%7%14%22%17%3
2292
September1st to 15thDay
35%7%13%21%19%3
2160
16th to endDay
43%6%8%20%19%1
1998
October1st to 15thDay
38%49%26%18%2
1707
16th to endDay
34%47%26%21%4
1760
November1st to 15thDay
36%410%23%20%4
1622
16th to endDay
36%310%25%20%3
1539
December1st to 15thDay
38%6%12%23%15%3
1440
16th to endDay
45%49%23%16%1
1536
January1st to 15thNight
41%5%10%20%17%4
2419
16th to endNight
42%39%24%16%2
2496
February1st to 15thNight
39%38%26%19%3
2278
16th to endNight
38%48%26%19%3
1893
March1st to 15thNight
38%5%10%28%14%3
2025
16th to endNight
42%49%22%17%3
2070
April1st to 15thNight
38%5%9%21%21%3
1796
16th to endNight
37%5%9%21%19%6%
1800
May1st to 15thNight
42%7%12%22%13%2
1686
16th to endNight
36%8%15%24%14%1
1497
June1st to 15thNight
34%8%12%26%15%1
1440
16th to endNight
37%8%13%18%19%2
1440
July1st to 15thNight
38%9%17%19%12%3
1360
16th to endNight
31%9%15%27%14%1
1576
August1st to 15thNight
35%9%14%21%17%
1638
16th to endNight
37%7%14%22%16%1
1910
September1st to 15thNight
36%6%13%20%19%4
1800
16th to endNight
41%6%9%19%20%3
1959
October1st to 15thNight
40%5%7%26%16%3
2051
16th to endNight
34%47%26%22%4
2112
November1st to 15thNight
37%48%22%20%6%
2233
16th to endNight
38%5%8%24%17%5%
2418
December1st to 15thNight
42%411%23%14%3
2520
16th to endNight
42%312%23%14%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
17%435%35%6%1
74
16th to endDay
19%9%28%32%10%
96
February1st to 15thDay
21%10%22%38%7%
98
16th to endDay
15%8%34%33%7%
239
March1st to 15thDay
16%8%31%31%12%
270
16th to endDay
19%5%29%30%10%4
288
April1st to 15thDay
14%6%28%28%18%2
270
16th to endDay
17%7%20%24%23%6%
270
May1st to 15thDay
22%426%30%12%4
288
16th to endDay
19%113%24%25%15%
331
June1st to 15thDay
13%212%32%23%16%
315
16th to endDay
8%111%34%35%8%
315
July1st to 15thDay
10%7%31%40%9%
305
16th to endDay
6%7%25%42%16%
326
August1st to 15thDay
14%8%27%34%14%
313
16th to endDay
10%16%24%37%19%
332
September1st to 15thDay
13%212%27%25%18%
315
16th to endDay
22%214%20%27%11%
314
October1st to 15thDay
20%414%26%23%11%
278
16th to endDay
11%7%25%28%21%5%
272
November1st to 15thDay
20%5%26%21%21%5%
242
16th to endDay
16%8%26%30%12%5%
159
December1st to 15thDay
18%6%21%31%16%5%
60
16th to endDay
29%126%32%9%
64
January1st to 15thNight
18%11%37%25%6%
720
16th to endNight
20%12%36%27%2
768
February1st to 15thNight
18%11%38%29%2
704
16th to endNight
17%12%39%26%3
631
March1st to 15thNight
17%7%36%31%6%
720
16th to endNight
19%6%32%29%9%1
768
April1st to 15thNight
17%334%33%9%
718
16th to endNight
19%5%21%37%15%
720
May1st to 15thNight
17%327%34%14%2
606
16th to endNight
14%215%33%31%2
375
June1st to 15thNight
10%114%36%31%4
360
16th to endNight
8%113%41%31%2
360
July1st to 15thNight
11%10%34%37%5%
340
16th to endNight
6%10%36%37%8%
545
August1st to 15thNight
10%19%41%33%4
568
16th to endNight
13%17%34%35%7%
764
September1st to 15thNight
15%110%31%34%6%
720
16th to endNight
19%313%29%28%5%
717
October1st to 15thNight
20%5%17%29%21%6%
684
16th to endNight
18%10%28%24%17%1
704
November1st to 15thNight
17%9%27%27%16%3
700
16th to endNight
16%12%28%29%11%1
720
December1st to 15thNight
19%10%32%22%12%1
720
16th to endNight
19%10%36%28%4
768
Page generated at 2017-10-07 14:07:54. Version ac04

Copyright 2017 A. Danko


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