Tryon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tryon clear sky chart from 2005-11-05 to 2018-02-13.

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
42%
16690
23%
48732
13%
16644
51%
16644
35%
28381

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
36%
975
23%
2716
12%
970
46%
970
35%
1586
January16th to endNight
33%
1040
26%
2905
11%
1040
44%
1040
36%
1708
February1st to 15thNight
27%
806
17%
2314
7%
802
36%
802
26%
1480
February16th to endNight
32%
632
25%
1894
9%
632
44%
632
34%
1113
March1st to 15thNight
37%
702
24%
2142
12%
702
47%
702
35%
1216
March16th to endNight
34%
576
18%
2061
13%
576
44%
576
27%
1194
April1st to 15thNight
30%
539
17%
1798
10%
539
42%
539
26%
1093
April16th to endNight
32%
540
16%
1668
12%
540
41%
540
22%
1120
May1st to 15thNight
42%
540
18%
1620
12%
540
50%
540
31%
969
May16th to endNight
40%
562
16%
1586
8%
561
46%
561
27%
1054
June1st to 15thNight
41%
540
14%
1440
4%
540
45%
540
33%
923
June16th to endNight
57%
540
18%
1440
9%
540
60%
540
44%
830
July1st to 15thNight
61%
510
16%
1360
9%
510
64%
510
41%
804
July16th to endNight
67%
564
25%
1424
18%
531
70%
531
47%
787
August1st to 15thNight
64%
539
19%
1610
18%
536
67%
536
34%
961
August16th to endNight
62%
573
25%
1868
24%
573
70%
573
43%
970
September1st to 15thNight
53%
540
25%
1866
20%
540
64%
540
38%
951
September16th to endNight
51%
537
30%
1980
25%
537
62%
537
37%
961
October1st to 15thNight
45%
540
30%
1980
23%
540
55%
540
29%
1090
October16th to endNight
48%
955
32%
2491
15%
955
56%
955
46%
1372
November1st to 15thNight
46%
950
31%
2470
13%
950
55%
950
46%
1388
November16th to endNight
44%
975
32%
2535
15%
975
55%
975
45%
1448
December1st to 15thNight
33%
975
22%
2652
9%
975
43%
975
35%
1572
December16th to endNight
35%
1040
24%
2912
9%
1040
47%
1040
32%
1791

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
8%5%2442345%7%52%
49330
Night
7%5%2442445%7%51%
48905
Cloud CoverDay
8%5%2442345%7%52%
49328
Night
7%5%2442445%7%51%
48905
TransparencyDay
30%5%14%27%17%3
49006
Night
30%5%15%27%17%3
48732
SeeingDay
10%6%29%33%16%3
6434
Night
9%7%35%36%10%
16695

By Month

Percentage Cloud Cover SW (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
5%6%246%34446%50%
1552
16th to endDay
6%43342435%7%52%
1671
February1st to 15thDay
8%8%46%5%3445%7%42%
1825
16th to endDay
6%6%2442235%7%53%
1580
March1st to 15thDay
6%42332345%8%55%
1818
16th to endDay
10%8%345%2435%9%43%
2160
April1st to 15thDay
12%6%24423346%48%
2150
16th to endDay
16%7%25%423446%41%
2292
May1st to 15thDay
11%425%423447%47%
2331
16th to endDay
15%5%24323447%46%
2526
June1st to 15thDay
10%41342346%7%51%
2520
16th to endDay
32122135%5%8%62%
2520
July1st to 15thDay
7%2144245%5%8%52%
2520
16th to endDay
43133345%6%9%54%
2647
August1st to 15thDay
7%425%5%245%7%9%46%
2340
16th to endDay
5%31442435%6%58%
2333
September1st to 15thDay
9%41331345%6%56%
2094
16th to endDay
7%413312345%62%
1980
October1st to 15thDay
13%5%13213235%55%
1968
16th to endDay
8%413323335%58%
1731
November1st to 15thDay
442432445%7%54%
1718
16th to endDay
5%5%1322245%5%59%
1755
December1st to 15thDay
6%8%245%2235%6%51%
1635
16th to endDay
6%5%36%434447%48%
1664
January1st to 15thNight
45%25%4245%5%9%50%
2716
16th to endNight
5%6%24425%45%6%53%
2905
February1st to 15thNight
7%9%37%5%23447%43%
2304
16th to endNight
5%5%246%345%5%6%50%
1894
March1st to 15thNight
6%6%2432435%7%53%
2142
16th to endNight
9%6%2342435%7%47%
2061
April1st to 15thNight
11%8%23424347%45%
1798
16th to endNight
16%7%25%5%23446%39%
1668
May1st to 15thNight
10%5%143245%5%9%46%
1619
16th to endNight
14%6%2442435%7%42%
1584
June1st to 15thNight
10%6%23325%5%6%8%45%
1440
16th to endNight
33144245%6%9%53%
1440
July1st to 15thNight
5%3134245%7%10%51%
1440
16th to endNight
221332446%9%57%
1520
August1st to 15thNight
5%3145%35%47%8%48%
1620
16th to endNight
421332345%8%58%
1868
September1st to 15thNight
8%41331346%6%57%
1866
16th to endNight
7%313323336%60%
1980
October1st to 15thNight
12%5%23313336%53%
1980
16th to endNight
7%313312345%61%
2491
November1st to 15thNight
432342445%7%57%
2470
16th to endNight
5%31342435%8%56%
2535
December1st to 15thNight
6%6%35%423348%51%
2652
16th to endNight
5%6%36%5%24448%48%
2912

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
5%6%25%5%34446%50%
1552
16th to endDay
6%42432445%6%53%
1671
February1st to 15thDay
8%7%47%5%3445%6%42%
1825
16th to endDay
6%6%2442235%6%53%
1580
March1st to 15thDay
6%41321445%8%55%
1818
16th to endDay
10%7%345%3445%8%42%
2158
April1st to 15thDay
13%6%25%423346%48%
2150
16th to endDay
16%7%35%423446%41%
2292
May1st to 15thDay
11%424423447%47%
2331
16th to endDay
15%5%2431445%6%46%
2526
June1st to 15thDay
10%41342445%7%51%
2520
16th to endDay
321221346%8%63%
2520
July1st to 15thDay
7%21342446%8%52%
2520
16th to endDay
42134245%6%9%54%
2647
August1st to 15thDay
7%4245%345%8%10%45%
2340
16th to endDay
5%31333435%7%58%
2333
September1st to 15thDay
9%41321345%7%56%
2094
16th to endDay
7%412213245%62%
1980
October1st to 15thDay
13%6%23313235%55%
1968
16th to endDay
8%5%13323346%58%
1731
November1st to 15thDay
442342445%8%54%
1718
16th to endDay
5%423313446%58%
1755
December1st to 15thDay
6%7%26%5%13447%50%
1635
16th to endDay
6%5%36%5%34338%48%
1664
January1st to 15thNight
45%25%42445%9%50%
2716
16th to endNight
5%5%24424446%53%
2905
February1st to 15thNight
7%9%36%6%23447%43%
2304
16th to endNight
46%245%25%45%6%50%
1894
March1st to 15thNight
6%6%2432335%7%52%
2142
16th to endNight
10%6%3442445%8%46%
2061
April1st to 15thNight
11%8%33324446%46%
1798
16th to endNight
17%7%25%424446%39%
1668
May1st to 15thNight
11%5%233245%5%8%47%
1619
16th to endNight
15%5%2442446%7%42%
1584
June1st to 15thNight
11%5%23325%5%6%8%44%
1440
16th to endNight
3223435%46%8%54%
1440
July1st to 15thNight
5%32342447%9%52%
1440
16th to endNight
22134245%5%10%57%
1520
August1st to 15thNight
6%314435%5%7%8%48%
1620
16th to endNight
5%31332245%7%58%
1868
September1st to 15thNight
7%41322336%7%56%
1866
16th to endNight
8%313323337%60%
1980
October1st to 15thNight
11%5%24313335%53%
1980
16th to endNight
7%313222346%61%
2491
November1st to 15thNight
432342445%8%56%
2470
16th to endNight
5%313423447%57%
2535
December1st to 15thNight
6%6%35%5%2325%7%52%
2652
16th to endNight
5%6%36%424447%48%
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
34%5%15%27%14%2
1553
16th to endDay
29%5%19%27%14%3
1671
February1st to 15thDay
41%5%15%24%10%2
1826
16th to endDay
30%415%30%16%3
1580
March1st to 15thDay
26%5%15%27%20%4
1818
16th to endDay
38%6%17%21%13%1
2160
April1st to 15thDay
36%414%30%11%1
2150
16th to endDay
42%5%14%22%13%1
2292
May1st to 15thDay
35%5%16%27%13%
2331
16th to endDay
36%6%20%21%11%2
2530
June1st to 15thDay
30%7%17%27%13%3
2520
16th to endDay
17%5%15%32%23%5%
2520
July1st to 15thDay
28%6%13%26%19%6%
2371
16th to endDay
22%6%15%28%21%4
2480
August1st to 15thDay
30%8%18%24%13%4
2326
16th to endDay
25%412%29%21%6%
2333
September1st to 15thDay
26%410%26%21%9%
2094
16th to endDay
23%310%31%28%3
1980
October1st to 15thDay
32%48%27%22%4
1968
16th to endDay
28%410%31%21%4
1731
November1st to 15thDay
26%5%13%27%21%5%
1718
16th to endDay
25%314%32%20%3
1755
December1st to 15thDay
33%5%14%32%12%2
1635
16th to endDay
35%416%26%14%2
1664
January1st to 15thNight
30%5%17%29%15%1
2716
16th to endNight
29%5%15%29%18%2
2905
February1st to 15thNight
39%6%16%25%10%2
2314
16th to endNight
31%5%15%27%14%5%
1894
March1st to 15thNight
30%412%28%19%4
2142
16th to endNight
35%6%15%24%15%2
2061
April1st to 15thNight
38%5%13%25%14%2
1798
16th to endNight
44%6%12%21%13%1
1668
May1st to 15thNight
33%6%19%23%15%
1620
16th to endNight
40%7%17%22%9%2
1586
June1st to 15thNight
34%7%19%23%11%3
1440
16th to endNight
24%6%19%28%17%3
1440
July1st to 15thNight
26%8%17%27%16%4
1360
16th to endNight
21%7%15%31%21%3
1424
August1st to 15thNight
30%9%19%23%13%4
1610
16th to endNight
23%6%13%27%22%7%
1868
September1st to 15thNight
26%412%24%23%7%
1866
16th to endNight
24%410%29%25%4
1980
October1st to 15thNight
32%49%24%23%4
1980
16th to endNight
23%312%29%23%7%
2491
November1st to 15thNight
24%412%29%22%6%
2470
16th to endNight
25%414%28%23%4
2535
December1st to 15thNight
31%416%31%13%2
2652
16th to endNight
34%5%17%25%15%1
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
8%8%36%32%10%2
135
16th to endDay
9%5%44%25%11%3
144
February1st to 15thDay
15%8%49%21%5%
126
16th to endDay
6%7%44%32%6%3
81
March1st to 15thDay
10%6%42%27%13%
90
16th to endDay
16%12%30%27%9%2
144
April1st to 15thDay
14%10%36%30%8%
269
16th to endDay
20%10%33%24%10%
402
May1st to 15thDay
12%10%29%30%15%1
468
16th to endDay
20%6%28%29%12%2
517
June1st to 15thDay
9%5%29%32%17%5%
495
16th to endDay
4432%38%18%1
495
July1st to 15thDay
9%220%38%24%3
475
16th to endDay
4121%43%25%3
515
August1st to 15thDay
8%320%41%22%3
493
16th to endDay
6%125%40%21%4
373
September1st to 15thDay
45%23%41%16%8%
249
16th to endDay
14%221%39%18%2
135
October1st to 15thDay
15%134%26%18%3
135
16th to endDay
8%12%24%33%17%4
144
November1st to 15thDay
6%25%37%20%8%
135
16th to endDay
16%9%38%25%9%
135
December1st to 15thDay
9%11%51%17%6%2
135
16th to endDay
11%13%44%25%41
144
January1st to 15thNight
7%11%38%33%7%
975
16th to endNight
7%10%43%31%6%
1040
February1st to 15thNight
10%9%44%29%5%
810
16th to endNight
8%9%46%29%6%
632
March1st to 15thNight
8%8%41%34%6%
702
16th to endNight
12%6%41%32%6%
576
April1st to 15thNight
15%9%42%30%2
539
16th to endNight
19%10%35%26%8%
540
May1st to 15thNight
12%6%32%37%10%
540
16th to endNight
17%432%35%8%
563
June1st to 15thNight
13%437%33%10%
540
16th to endNight
3331%49%12%
540
July1st to 15thNight
6%122%50%17%
510
16th to endNight
2122%54%18%
564
August1st to 15thNight
7%18%52%19%
539
16th to endNight
5%125%50%17%
573
September1st to 15thNight
10%229%43%13%
540
16th to endNight
10%5%29%37%16%1
537
October1st to 15thNight
16%8%27%37%10%
540
16th to endNight
9%7%30%38%12%1
955
November1st to 15thNight
6%7%36%38%10%
950
16th to endNight
7%6%38%37%9%
975
December1st to 15thNight
8%11%42%29%6%
975
16th to endNight
9%10%38%34%7%
1040
Page generated at 2018-02-13 19:45:58. Version ac04

Copyright 2018 A. Danko


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