Tripp
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tripp clear sky chart from 2005-11-06 to 2024-01-13.

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
39%
24767
20%
74678
11%
24709
47%
24709
29%
46342

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 10thNight
33%
950
18%
2647
8%
946
41%
946
23%
1798
January11th to 20thNight
31%
915
16%
2562
8%
915
37%
915
21%
1796
January21st to endNight
25%
990
18%
2605
6%
990
33%
990
22%
1869
February1st to 10thNight
27%
900
13%
2340
4%
900
33%
900
24%
1636
February11th to 20thNight
30%
808
16%
2203
7%
804
36%
804
25%
1463
February21st to endNight
34%
592
21%
1776
7%
592
45%
592
25%
1157
March1st to 10thNight
30%
666
18%
2106
8%
666
38%
666
25%
1335
March11th to 20thNight
30%
540
21%
1980
13%
540
42%
540
22%
1210
March21st to endNight
28%
594
15%
2178
9%
594
37%
594
18%
1431
April1st to 10thNight
28%
540
16%
1900
9%
540
40%
540
23%
1167
April11th to 20thNight
31%
533
23%
1603
15%
533
43%
533
23%
1030
April21st to endNight
32%
540
19%
1620
14%
540
42%
540
26%
1041
May1st to 10thNight
36%
540
17%
1620
10%
540
44%
540
29%
1017
May11th to 20thNight
40%
531
18%
1593
9%
531
48%
531
29%
996
May21st to endNight
39%
583
14%
1692
5%
582
44%
582
26%
1112
June1st to 10thNight
54%
540
22%
1260
7%
540
57%
540
43%
787
June11th to 20thNight
47%
540
21%
1260
7%
540
51%
540
44%
795
June21st to endNight
59%
540
22%
1260
7%
540
62%
540
49%
751
July1st to 10thNight
62%
525
17%
1372
8%
525
63%
525
44%
798
July11th to 20thNight
65%
522
23%
1392
11%
522
69%
522
51%
754
July21st to endNight
64%
591
24%
1625
16%
558
67%
558
44%
875
August1st to 10thNight
59%
537
19%
1601
17%
534
62%
534
36%
936
August11th to 20thNight
59%
534
26%
1600
24%
534
67%
534
42%
886
August21st to endNight
58%
594
30%
1782
26%
594
69%
594
48%
907
September1st to 10thNight
53%
540
22%
1895
20%
540
62%
540
34%
1011
September11th to 20thNight
55%
540
30%
1980
28%
540
66%
540
38%
983
September21st to endNight
43%
540
31%
1980
20%
540
60%
540
36%
978
October1st to 10thNight
39%
594
27%
2034
19%
594
48%
594
28%
1182
October11th to 20thNight
35%
720
28%
2160
14%
720
46%
720
34%
1232
October21st to endNight
37%
926
26%
2510
12%
926
45%
926
33%
1542
November1st to 10thNight
38%
925
28%
2405
11%
925
48%
925
38%
1429
November11th to 20thNight
33%
950
26%
2485
10%
950
43%
950
33%
1567
November21st to endNight
35%
950
23%
2660
12%
950
43%
950
33%
1616
December1st to 10thNight
29%
950
18%
2660
7%
950
38%
950
26%
1753
December11th to 20thNight
33%
948
19%
3280
9%
948
40%
948
23%
1970
December21st to endNight
28%
1039
12%
5052
8%
1026
38%
1026
12%
3532

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
11%6%36%5%3445%7%45%
74640
Night
10%7%36%5%3445%7%47%
75103
TransparencyDay
38%6%14%26%14%2
74352
Night
36%6%13%26%16%2
74914
SeeingDay
14%9%31%30%13%2
14733
Night
12%9%35%34%10%1
24776

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 10thDay
8%9%5%7%6%46%6%5%7%37%
1518
11th to 20thDay
7%9%5%9%7%46%5%6%7%35%
1460
21st to endDay
9%10%5%10%7%46%5%5%7%31%
1749
February1st to 10thDay
11%8%47%8%45%6%5%7%36%
1620
11th to 20thDay
9%9%5%9%6%45%5%5%6%38%
1661
21st to endDay
10%9%48%6%45%46%7%38%
1480
March1st to 10thDay
11%8%48%7%3335%7%42%
1854
11th to 20thDay
12%7%38%6%4446%7%38%
1980
21st to endDay
17%12%5%7%6%245%5%6%31%
2178
April1st to 10thDay
16%6%36%5%3446%7%40%
2056
11th to 20thDay
19%8%35%434446%41%
2304
21st to endDay
18%7%36%5%3445%6%40%
2340
May1st to 10thDay
15%6%26%5%35%46%6%40%
2340
11th to 20thDay
15%7%37%5%33447%41%
2302
21st to endDay
16%6%25%6%345%5%8%38%
2577
June1st to 10thDay
10%42443446%9%50%
2700
11th to 20thDay
12%5%24435%46%9%47%
2700
21st to endDay
7%5%244345%6%9%52%
2700
July1st to 10thDay
7%3244346%6%10%52%
2542
11th to 20thDay
6%3133235%5%8%61%
2520
21st to endDay
6%4244345%6%8%56%
2594
August1st to 10thDay
10%5%25%5%35%6%6%9%45%
2328
11th to 20thDay
8%5%25%4245%6%9%52%
2301
21st to endDay
6%32443445%7%59%
2574
September1st to 10thDay
13%5%2442435%6%53%
2060
11th to 20thDay
9%424324446%59%
1980
21st to endDay
11%42433345%7%55%
1980
October1st to 10thDay
13%5%1442445%5%51%
1906
11th to 20thDay
12%7%25%32345%5%54%
1800
21st to endDay
15%7%25%322347%49%
1843
November1st to 10thDay
7%7%345%25%5%6%7%49%
1673
11th to 20thDay
6%6%27%7%45%5%5%7%46%
1691
21st to endDay
9%8%36%5%2446%7%46%
1520
December1st to 10thDay
7%8%37%7%35%5%6%8%41%
1520
11th to 20thDay
8%9%46%6%36%6%5%8%39%
1745
21st to endDay
16%10%5%11%8%3445%5%30%
2544
January1st to 10thNight
7%8%37%7%5%6%5%6%7%38%
2647
11th to 20thNight
6%10%5%10%8%45%46%7%36%
2562
21st to endNight
7%11%49%7%45%5%6%7%35%
2605
February1st to 10thNight
9%9%47%7%45%5%5%6%39%
2340
11th to 20thNight
8%9%37%6%35%5%5%6%43%
2202
21st to endNight
9%8%36%6%346%6%5%44%
1776
March1st to 10thNight
10%7%37%5%345%5%8%43%
2106
11th to 20thNight
11%8%36%6%3445%7%43%
1980
21st to endNight
14%10%36%6%3445%7%38%
2178
April1st to 10thNight
13%8%35%4245%6%7%43%
1900
11th to 20thNight
14%8%36%5%2445%8%42%
1603
21st to endNight
14%6%35%43446%8%42%
1620
May1st to 10thNight
14%5%25%5%3445%8%46%
1620
11th to 20thNight
14%6%244345%5%8%47%
1593
21st to endNight
16%6%25%5%3346%8%42%
1691
June1st to 10thNight
8%4245%2335%8%56%
1260
11th to 20thNight
8%424335%47%10%52%
1260
21st to endNight
6%312335%449%59%
1260
July1st to 10thNight
5%5%134345%5%8%57%
1412
11th to 20thNight
421233446%7%63%
1440
21st to endNight
32145%25%5%6%8%57%
1721
August1st to 10thNight
6%5%25%5%25%5%7%10%48%
1611
11th to 20thNight
6%324425%45%7%58%
1600
21st to endNight
5%21332346%8%61%
1782
September1st to 10thNight
9%423434447%56%
1895
11th to 20thNight
7%41332445%7%61%
1980
21st to endNight
9%424323346%61%
1980
October1st to 10thNight
17%5%24323446%51%
2034
11th to 20thNight
11%6%24323436%56%
2160
21st to endNight
12%6%23424445%54%
2510
November1st to 10thNight
8%41443445%7%55%
2405
11th to 20thNight
8%6%26%6%345%5%8%47%
2485
21st to endNight
8%7%35%43445%8%49%
2660
December1st to 10thNight
8%6%48%5%45%45%6%43%
2660
11th to 20thNight
6%7%36%6%345%5%8%45%
3447
21st to endNight
16%10%5%11%6%34435%33%
5118

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 10thDay
46%6%17%19%11%
1519
11th to 20thDay
48%7%15%19%10%1
1460
21st to endDay
52%7%17%17%6%
1749
February1st to 10thDay
48%7%16%19%9%1
1620
11th to 20thDay
46%6%12%21%13%2
1670
21st to endDay
46%6%15%20%11%3
1480
March1st to 10thDay
44%6%13%25%11%2
1854
11th to 20thDay
44%7%12%24%11%1
1980
21st to endDay
54%7%16%17%5%1
2178
April1st to 10thDay
43%6%13%25%12%1
2056
11th to 20thDay
45%6%12%21%14%2
2307
21st to endDay
44%6%13%26%11%
2340
May1st to 10thDay
43%8%11%24%13%
2340
11th to 20thDay
43%6%14%24%12%
2306
21st to endDay
44%8%15%21%12%1
2577
June1st to 10thDay
31%8%17%30%13%1
2700
11th to 20thDay
33%8%16%24%17%3
2700
21st to endDay
28%8%17%30%15%2
2700
July1st to 10thDay
27%8%16%34%14%2
2473
11th to 20thDay
22%6%11%30%23%8%
2445
21st to endDay
24%8%15%29%20%4
2450
August1st to 10thDay
34%8%16%28%11%3
2314
11th to 20thDay
29%7%15%32%15%1
2301
21st to endDay
25%7%11%30%21%5%
2574
September1st to 10thDay
32%6%12%27%19%4
2060
11th to 20thDay
27%5%14%33%19%1
1980
21st to endDay
29%6%11%30%22%1
1980
October1st to 10thDay
35%6%11%27%21%1
1906
11th to 20thDay
33%411%31%17%4
1800
21st to endDay
37%5%12%27%17%3
1843
November1st to 10thDay
34%7%16%25%16%3
1673
11th to 20thDay
39%6%14%26%14%1
1691
21st to endDay
37%416%27%14%1
1520
December1st to 10thDay
42%6%16%23%10%2
1520
11th to 20thDay
43%6%19%25%7%
1742
21st to endDay
57%410%23%5%1
2544
January1st to 10thNight
43%7%14%22%13%1
2647
11th to 20thNight
46%7%16%22%8%1
2562
21st to endNight
47%8%14%20%11%1
2605
February1st to 10thNight
45%6%15%21%12%1
2340
11th to 20thNight
42%6%15%21%13%4
2203
21st to endNight
40%7%13%24%12%3
1776
March1st to 10thNight
40%6%15%26%11%2
2106
11th to 20thNight
42%410%26%16%2
1980
21st to endNight
46%7%14%23%9%1
2178
April1st to 10thNight
40%6%14%23%15%1
1900
11th to 20thNight
41%6%10%23%19%1
1603
21st to endNight
39%7%13%26%13%2
1620
May1st to 10thNight
38%6%15%25%14%2
1620
11th to 20thNight
35%8%12%25%19%1
1594
21st to endNight
40%7%15%22%13%2
1692
June1st to 10thNight
27%8%15%30%20%2
1260
11th to 20thNight
27%8%14%25%21%5%
1260
21st to endNight
23%6%15%32%20%3
1260
July1st to 10thNight
25%7%14%31%19%4
1372
11th to 20thNight
19%7%13%29%23%9%
1392
21st to endNight
22%8%13%30%22%5%
1625
August1st to 10thNight
30%8%18%26%16%3
1601
11th to 20thNight
25%7%12%33%20%3
1600
21st to endNight
20%6%15%29%24%6%
1782
September1st to 10thNight
28%7%11%26%21%7%
1895
11th to 20thNight
23%7%11%34%22%2
1980
21st to endNight
26%49%31%27%3
1980
October1st to 10thNight
35%5%11%24%23%2
2034
11th to 20thNight
31%5%8%30%22%5%
2160
21st to endNight
33%6%14%22%23%2
2510
November1st to 10thNight
29%5%14%25%22%5%
2405
11th to 20thNight
35%5%13%25%19%3
2485
21st to endNight
33%6%14%28%17%1
2660
December1st to 10thNight
41%6%14%27%11%1
2660
11th to 20thNight
38%5%16%33%8%
3449
21st to endNight
55%5%11%21%8%
5118

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 10thDay
15%11%32%28%13%1
270
11th to 20thDay
12%13%40%27%7%
248
21st to endDay
15%11%47%23%4
264
February1st to 10thDay
12%18%40%26%3
240
11th to 20thDay
16%13%45%20%6%1
240
21st to endDay
15%15%40%26%4
198
March1st to 10thDay
14%14%40%26%5%1
240
11th to 20thDay
20%8%38%23%10%2
240
21st to endDay
25%13%31%24%6%1
264
April1st to 10thDay
22%19%37%17%4
316
11th to 20thDay
23%15%30%25%6%1
585
21st to endDay
21%14%30%24%9%2
600
May1st to 10thDay
18%13%32%26%9%1
603
11th to 20thDay
20%10%29%25%13%2
625
21st to endDay
19%9%29%27%13%3
679
June1st to 10thDay
10%7%25%34%20%5%
630
11th to 20thDay
12%6%36%30%15%2
630
21st to endDay
9%7%27%37%18%2
630
July1st to 10thDay
7%321%39%27%4
621
11th to 20thDay
6%426%44%18%2
618
21st to endDay
6%325%45%19%2
684
August1st to 10thDay
9%223%41%21%3
626
11th to 20thDay
9%324%39%20%4
615
21st to endDay
7%427%39%20%4
693
September1st to 10thDay
15%5%32%28%16%4
350
11th to 20thDay
7%6%35%29%18%4
270
21st to endDay
17%9%34%27%12%1
270
October1st to 10thDay
19%5%29%29%14%4
270
11th to 20thDay
17%13%35%25%8%1
270
21st to endDay
19%16%37%19%9%1
297
November1st to 10thDay
17%14%33%23%9%3
270
11th to 20thDay
11%18%40%26%6%
270
21st to endDay
20%17%30%24%9%
270
December1st to 10thDay
13%10%38%29%10%1
270
11th to 20thDay
13%14%41%25%7%
270
21st to endDay
22%14%35%24%4
297
January1st to 10thNight
11%11%37%31%8%1
950
11th to 20thNight
10%14%37%32%7%1
915
21st to endNight
13%10%43%28%6%
990
February1st to 10thNight
15%11%41%27%6%
900
11th to 20thNight
13%12%39%30%6%1
808
21st to endNight
15%9%36%30%8%1
592
March1st to 10thNight
14%11%41%28%6%
666
11th to 20thNight
15%9%41%30%5%
540
21st to endNight
19%10%38%26%7%
594
April1st to 10thNight
16%14%39%29%3
540
11th to 20thNight
18%13%34%29%7%
533
21st to endNight
16%10%39%27%7%1
540
May1st to 10thNight
16%9%36%30%9%
540
11th to 20thNight
17%8%32%32%11%
531
21st to endNight
19%6%30%34%9%
584
June1st to 10thNight
9%5%27%41%16%1
540
11th to 20thNight
9%336%41%11%
540
21st to endNight
6%328%46%16%
540
July1st to 10thNight
6%221%47%22%1
525
11th to 20thNight
5%125%52%16%
522
21st to endNight
3224%55%15%
591
August1st to 10thNight
8%423%45%20%
537
11th to 20thNight
7%226%44%20%1
534
21st to endNight
6%329%45%17%1
594
September1st to 10thNight
11%5%28%42%13%2
540
11th to 20thNight
7%431%41%14%2
540
21st to endNight
10%9%34%33%12%1
540
October1st to 10thNight
20%8%31%32%9%1
594
11th to 20thNight
15%12%34%30%8%
720
21st to endNight
16%10%35%31%8%
926
November1st to 10thNight
11%10%37%32%8%1
925
11th to 20thNight
11%13%39%29%8%1
950
21st to endNight
11%11%37%31%8%
950
December1st to 10thNight
12%12%40%30%6%
950
11th to 20thNight
13%9%38%33%8%
950
21st to endNight
19%12%34%28%6%1
1045
Page generated at 2024-01-10 18:35:22. Version ac07

Copyright 2024 Attilla Danko


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