North Smoke Tower Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the North Smoke Tower Site clear sky chart from 2005-11-05 to 2017-04-09.

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
51%
15271
22%
45419
15%
15233
58%
15233
29%
28376

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%
716
21%
2327
11%
716
48%
716
24%
1432
January16th to endNight
35%
768
23%
2464
13%
768
47%
768
24%
1542
February1st to 15thNight
35%
701
23%
2106
12%
699
47%
699
27%
1279
February16th to endNight
35%
631
25%
1878
13%
631
47%
631
28%
1152
March1st to 15thNight
40%
720
27%
1980
13%
720
53%
720
33%
1206
March16th to endNight
44%
768
25%
2112
14%
768
52%
768
36%
1238
April1st to 15thNight
40%
694
24%
1910
15%
694
49%
694
34%
1169
April16th to endNight
50%
596
27%
1627
17%
596
56%
596
39%
944
May1st to 15thNight
61%
494
26%
1484
18%
494
66%
494
38%
841
May16th to endNight
70%
513
21%
1538
16%
513
73%
513
35%
908
June1st to 15thNight
67%
495
15%
1485
12%
495
68%
495
27%
976
June16th to endNight
75%
495
12%
1485
10%
495
77%
495
27%
997
July1st to 15thNight
73%
465
10%
1395
10%
465
73%
465
27%
931
July16th to endNight
73%
522
10%
1469
10%
489
74%
489
25%
999
August1st to 15thNight
74%
494
10%
1474
8%
491
75%
491
22%
1047
August16th to endNight
62%
610
12%
1817
12%
610
63%
610
19%
1302
September1st to 15thNight
63%
660
14%
1815
13%
660
63%
660
22%
1297
September16th to endNight
56%
657
15%
1815
13%
657
58%
657
23%
1280
October1st to 15thNight
57%
660
28%
1867
25%
660
62%
660
33%
1134
October16th to endNight
55%
704
30%
2112
26%
704
63%
704
35%
1207
November1st to 15thNight
50%
700
31%
2101
23%
700
61%
700
37%
1186
November16th to endNight
42%
720
28%
2322
19%
720
56%
720
32%
1312
December1st to 15thNight
42%
720
25%
2340
20%
720
51%
720
27%
1419
December16th to endNight
44%
768
23%
2496
18%
768
53%
768
23%
1578

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
10%6%36%6%35%5%5%7%38%
45852
Night
9%5%25%5%345%5%8%45%
45625
TransparencyDay
42%7%12%16%14%7%
45553
Night
35%7%14%19%15%8%
45428
SeeingDay
12%5%18%22%24%16%
5018
Night
11%6%22%32%22%4
15281

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
12%6%25%5%2445%8%41%
1611
16th to endDay
14%5%25%424445%45%
1758
February1st to 15thDay
15%6%35%423445%44%
1750
16th to endDay
13%6%35%42333449%
1593
March1st to 15thDay
9%42342445%7%51%
1980
16th to endDay
10%425%433446%47%
2111
April1st to 15thDay
10%5%246%34447%45%
1902
16th to endDay
8%4245%46%5%5%8%45%
2011
May1st to 15thDay
7%4246%345%6%9%45%
2136
16th to endDay
9%436%7%46%46%8%37%
2223
June1st to 15thDay
9%5%26%8%6%7%7%7%8%30%
2145
16th to endDay
8%5%27%8%48%7%8%10%27%
2145
July1st to 15thDay
7%6%49%9%5%7%7%9%10%22%
2145
16th to endDay
8%6%48%9%6%7%7%7%10%24%
2283
August1st to 15thDay
11%8%37%9%5%8%8%8%8%19%
2145
16th to endDay
13%8%47%8%48%7%7%8%21%
2019
September1st to 15thDay
11%7%38%8%5%7%6%7%8%24%
1815
16th to endDay
17%7%37%9%46%6%5%7%25%
1815
October1st to 15thDay
11%7%36%5%34446%43%
1763
16th to endDay
9%4245%2445%5%51%
1760
November1st to 15thDay
8%42341435%7%52%
1757
16th to endDay
10%5%25%43444451%
1637
December1st to 15thDay
13%6%25%6%3345%5%42%
1620
16th to endDay
12%7%35%5%345%47%40%
1728
January1st to 15thNight
12%6%245%2445%6%44%
2327
16th to endNight
14%5%34423446%44%
2464
February1st to 15thNight
13%6%25%422335%50%
2103
16th to endNight
13%6%25%423345%48%
1878
March1st to 15thNight
8%5%25%42445%6%51%
1980
16th to endNight
10%323423335%56%
2112
April1st to 15thNight
9%423423447%51%
1910
16th to endNight
7%42332345%7%55%
1627
May1st to 15thNight
5%213435%5%5%9%53%
1484
16th to endNight
7%31342446%10%49%
1538
June1st to 15thNight
8%3245%36%7%10%11%36%
1485
16th to endNight
6%225%5%38%7%8%13%35%
1485
July1st to 15thNight
5%326%5%36%7%9%13%35%
1485
16th to endNight
45%35%6%46%6%10%14%33%
1577
August1st to 15thNight
6%326%6%37%10%9%12%30%
1485
16th to endNight
10%6%26%6%45%7%7%11%31%
1817
September1st to 15thNight
8%5%27%7%46%5%6%12%32%
1815
16th to endNight
11%8%26%5%45%5%6%9%33%
1815
October1st to 15thNight
9%6%245%23347%49%
1867
16th to endNight
6%415%434447%53%
2112
November1st to 15thNight
8%32342435%8%53%
2101
16th to endNight
10%5%24423446%53%
2322
December1st to 15thNight
12%6%35%423447%45%
2340
16th to endNight
13%5%345%34447%43%
2496

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%48%16%17%10%
1612
16th to endDay
40%37%17%20%11%
1758
February1st to 15thDay
41%37%12%20%14%
1752
16th to endDay
39%38%14%21%13%
1593
March1st to 15thDay
32%48%21%23%9%
1980
16th to endDay
37%410%16%20%10%
2112
April1st to 15thDay
38%5%8%14%21%10%
1902
16th to endDay
36%6%9%18%18%10%
2011
May1st to 15thDay
34%6%11%20%19%6%
2136
16th to endDay
40%8%12%20%15%2
2227
June1st to 15thDay
47%10%15%16%9%
2145
16th to endDay
45%13%17%15%6%
2145
July1st to 15thDay
50%12%22%12%2
2006
16th to endDay
51%11%19%13%3
2128
August1st to 15thDay
54%13%18%10%2
2132
16th to endDay
57%11%16%11%2
2019
September1st to 15thDay
53%10%15%11%6%1
1815
16th to endDay
54%9%10%13%8%3
1815
October1st to 15thDay
41%48%16%17%11%
1763
16th to endDay
33%46%15%23%15%
1760
November1st to 15thDay
31%38%21%23%12%
1757
16th to endDay
35%47%15%22%14%
1637
December1st to 15thDay
42%48%20%15%7%
1620
16th to endDay
42%5%10%19%14%8%
1728
January1st to 15thNight
38%5%9%17%17%10%
2327
16th to endNight
40%47%13%21%12%
2464
February1st to 15thNight
37%37%14%20%15%
2112
16th to endNight
38%39%16%19%13%
1878
March1st to 15thNight
31%6%11%21%18%10%
1980
16th to endNight
31%412%19%21%11%
2112
April1st to 15thNight
32%6%10%18%22%10%
1910
16th to endNight
28%5%13%21%21%10%
1627
May1st to 15thNight
26%7%15%26%15%8%
1485
16th to endNight
28%8%16%28%14%3
1540
June1st to 15thNight
35%12%20%23%8%
1485
16th to endNight
35%13%23%20%6%1
1485
July1st to 15thNight
35%12%29%18%21
1395
16th to endNight
35%15%27%17%3
1469
August1st to 15thNight
37%17%27%14%2
1474
16th to endNight
42%14%22%15%4
1817
September1st to 15thNight
42%12%19%16%7%1
1815
16th to endNight
45%8%15%18%8%3
1815
October1st to 15thNight
34%5%10%18%19%10%
1867
16th to endNight
30%5%9%16%21%15%
2112
November1st to 15thNight
28%5%8%22%22%12%
2101
16th to endNight
32%49%18%19%15%
2322
December1st to 15thNight
37%411%22%16%6%
2340
16th to endNight
40%6%10%21%13%9%
2496

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
15%18%41%8%10%5%
90
16th to endDay
20%18%32%18%9%
96
February1st to 15thDay
24%14%36%15%7%1
90
16th to endDay
10%14%44%25%4
94
March1st to 15thDay
14%12%27%31%12%1
270
16th to endDay
11%8%34%20%20%5%
288
April1st to 15thDay
11%14%26%24%20%3
245
16th to endDay
8%5%23%27%20%13%
210
May1st to 15thDay
7%5%20%27%24%15%
228
16th to endDay
8%110%20%35%23%
267
June1st to 15thDay
10%110%18%28%29%
255
16th to endDay
9%316%33%36%
255
July1st to 15thDay
7%220%31%37%
245
16th to endDay
7%1419%31%35%
270
August1st to 15thDay
16%36%12%29%31%
253
16th to endDay
13%17%17%28%31%
268
September1st to 15thDay
14%7%22%28%26%
255
16th to endDay
25%27%18%29%16%
254
October1st to 15thDay
14%315%32%27%6%
255
16th to endDay
9%424%29%26%5%
272
November1st to 15thDay
12%330%27%20%5%
265
16th to endDay
11%14%36%17%16%3
107
December1st to 15thDay
10%14%42%18%12%2
90
16th to endDay
21%12%22%32%7%3
96
January1st to 15thNight
16%12%30%28%11%
720
16th to endNight
16%12%30%32%7%
768
February1st to 15thNight
15%13%30%30%8%
704
16th to endNight
14%13%30%35%5%
631
March1st to 15thNight
10%11%33%34%9%
720
16th to endNight
11%9%30%33%14%
768
April1st to 15thNight
10%9%34%34%10%
694
16th to endNight
10%6%27%37%17%1
596
May1st to 15thNight
5%224%47%18%2
495
16th to endNight
7%29%40%35%3
515
June1st to 15thNight
10%10%37%33%8%
495
16th to endNight
6%16%26%45%13%
495
July1st to 15thNight
7%5%24%45%16%
465
16th to endNight
5%15%26%47%14%
522
August1st to 15thNight
7%422%51%14%
494
16th to endNight
12%19%24%37%15%
610
September1st to 15thNight
11%18%28%37%11%
660
16th to endNight
17%113%31%29%5%
657
October1st to 15thNight
13%20%35%27%2
660
16th to endNight
7%5%25%35%24%1
704
November1st to 15thNight
9%5%29%36%19%
700
16th to endNight
12%7%33%29%16%1
720
December1st to 15thNight
14%10%26%31%16%
720
16th to endNight
15%10%23%33%17%
768
Page generated at 2017-04-10 09:00:38. Version ac04

Copyright 2017 A. Danko


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