Telescope Array Middle Drum FD
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Telescope Array Middle Drum FD 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
63%
15673
26%
47134
22%
15636
67%
15636
38%
26267

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
63%
716
19%
2327
18%
716
67%
716
30%
1386
January16th to endNight
62%
768
21%
2496
21%
768
65%
768
26%
1559
February1st to 15thNight
62%
699
18%
2241
17%
699
66%
699
27%
1387
February16th to endNight
53%
632
24%
1895
22%
632
58%
632
33%
1133
March1st to 15thNight
60%
720
27%
2046
22%
720
67%
720
40%
1162
March16th to endNight
53%
768
24%
2112
16%
768
59%
768
37%
1249
April1st to 15thNight
48%
692
22%
1874
13%
692
53%
692
35%
1130
April16th to endNight
45%
540
30%
1620
17%
540
56%
540
36%
900
May1st to 15thNight
52%
540
25%
1620
17%
540
56%
540
37%
908
May16th to endNight
58%
562
22%
1685
19%
561
62%
561
35%
952
June1st to 15thNight
62%
540
24%
1620
21%
540
67%
540
46%
813
June16th to endNight
67%
540
29%
1620
24%
540
74%
540
61%
717
July1st to 15thNight
70%
510
18%
1530
17%
510
72%
510
39%
840
July16th to endNight
72%
564
22%
1593
19%
531
73%
531
37%
884
August1st to 15thNight
66%
539
28%
1611
21%
536
71%
536
44%
843
August16th to endNight
75%
611
35%
1757
27%
611
78%
611
50%
885
September1st to 15thNight
76%
720
32%
1965
23%
720
81%
720
55%
999
September16th to endNight
73%
716
39%
1980
31%
716
77%
716
57%
969
October1st to 15thNight
70%
684
32%
1952
26%
684
75%
684
47%
1038
October16th to endNight
69%
704
34%
2139
29%
704
74%
704
48%
1061
November1st to 15thNight
67%
700
30%
2275
29%
700
71%
700
41%
1170
November16th to endNight
68%
720
30%
2340
31%
720
71%
720
42%
1200
December1st to 15thNight
63%
720
19%
2340
19%
720
66%
720
31%
1367
December16th to endNight
53%
768
17%
2496
15%
768
56%
768
19%
1715

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
342442445%7%55%
48063
Night
45%2442445%7%54%
47328
TransparencyDay
27%410%20%20%15%
47758
Night
28%410%22%20%13%
47134
SeeingDay
7%8%20%30%24%10%
5481
Night
6%418%38%27%4
15683

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
47%38%6%5%6%5%5%7%37%
1611
16th to endDay
6%6%36%7%46%6%6%8%37%
1728
February1st to 15thDay
38%36%7%36%7%7%8%38%
1619
16th to endDay
47%35%6%25%45%8%46%
1579
March1st to 15thDay
35%25%43445%8%51%
1914
16th to endDay
6%7%345%3445%7%46%
2112
April1st to 15thDay
45%25%5%35%6%46%51%
2069
16th to endDay
4414424447%56%
2340
May1st to 15thDay
33144245%6%8%55%
2331
16th to endDay
44135%25%5%5%7%52%
2429
June1st to 15thDay
231332445%7%61%
2340
16th to endDay
11121123478%
2340
July1st to 15thDay
22134245%5%8%58%
2340
16th to endDay
32144346%6%7%56%
2467
August1st to 15thDay
121343446%7%60%
2340
16th to endDay
22232345%7%63%
2443
September1st to 15thDay
323223345%67%
1994
16th to endDay
2211212345%73%
1980
October1st to 15thDay
5%314324346%60%
1805
16th to endDay
3413223346%63%
1730
November1st to 15thDay
441433445%6%55%
1584
16th to endDay
45%45%433446%53%
1620
December1st to 15thDay
47%36%8%46%5%5%8%39%
1620
16th to endDay
6%10%5%10%9%35%5%5%7%31%
1728
January1st to 15thNight
47%35%5%2445%8%48%
2327
16th to endNight
5%8%35%5%35%46%7%44%
2496
February1st to 15thNight
46%25%6%35%5%6%6%45%
2230
16th to endNight
47%26%43445%6%49%
1895
March1st to 15thNight
4424435%45%8%52%
2046
16th to endNight
5%5%24435%5%5%8%49%
2112
April1st to 15thNight
5%5%35%4245%5%7%50%
1874
16th to endNight
6%5%24323447%54%
1620
May1st to 15thNight
5%5%244245%6%6%53%
1619
16th to endNight
5%4245%4445%7%50%
1684
June1st to 15thNight
331431445%7%61%
1620
16th to endNight
212213235%73%
1620
July1st to 15thNight
5%3145%35%5%6%8%51%
1620
16th to endNight
3324435%7%6%8%49%
1701
August1st to 15thNight
23244245%7%7%54%
1620
16th to endNight
23143135%5%7%60%
1757
September1st to 15thNight
3213323436%65%
1965
16th to endNight
321231232471%
1980
October1st to 15thNight
441332335%7%60%
1952
16th to endNight
331332335%6%63%
2139
November1st to 15thNight
442431335%5%59%
2275
16th to endNight
35%24423446%59%
2340
December1st to 15thNight
6%6%25%43445%8%47%
2340
16th to endNight
7%9%46%6%5%5%45%8%36%
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
43%9%20%20%6%
1612
16th to endDay
43%9%17%21%7%
1728
February1st to 15thDay
40%8%18%20%11%1
1619
16th to endDay
34%5%13%30%15%
1579
March1st to 15thDay
28%413%31%17%3
1914
16th to endDay
35%412%27%14%5%
2112
April1st to 15thDay
31%411%24%21%7%
2069
16th to endDay
27%38%23%27%9%
2340
May1st to 15thDay
24%38%20%29%13%
2331
16th to endDay
28%48%19%26%12%
2432
June1st to 15thDay
20%35%14%31%24%
2340
16th to endDay
11%127%23%53%
2340
July1st to 15thDay
21%37%13%17%37%
2201
16th to endDay
24%38%13%20%29%
2312
August1st to 15thDay
21%35%13%21%34%
2325
16th to endDay
18%26%14%25%32%
2443
September1st to 15thDay
18%46%11%25%34%
1994
16th to endDay
14%25%20%31%25%
1980
October1st to 15thDay
24%39%24%31%7%
1805
16th to endDay
20%310%31%31%3
1730
November1st to 15thDay
28%5%13%29%19%2
1584
16th to endDay
32%415%29%17%2
1620
December1st to 15thDay
41%9%16%25%6%
1620
16th to endDay
52%7%15%18%6%
1728
January1st to 15thNight
33%7%20%27%10%
2327
16th to endNight
38%6%15%25%12%1
2496
February1st to 15thNight
37%6%15%25%12%1
2241
16th to endNight
33%5%13%29%17%
1895
March1st to 15thNight
28%410%30%21%4
2046
16th to endNight
31%410%27%19%6%
2112
April1st to 15thNight
32%49%25%20%7%
1874
16th to endNight
29%38%23%28%6%
1620
May1st to 15thNight
30%47%17%28%12%
1620
16th to endNight
31%39%19%24%11%
1685
June1st to 15thNight
22%36%12%28%26%
1620
16th to endNight
15%128%21%51%
1620
July1st to 15thNight
29%36%9%12%37%
1530
16th to endNight
29%5%8%13%15%28%
1593
August1st to 15thNight
24%48%15%16%30%
1611
16th to endNight
20%36%12%23%33%
1757
September1st to 15thNight
19%26%12%22%35%
1965
16th to endNight
18%15%16%29%28%
1980
October1st to 15thNight
23%47%20%32%11%
1952
16th to endNight
20%37%24%36%6%
2139
November1st to 15thNight
25%310%28%23%8%
2275
16th to endNight
25%311%33%22%3
2340
December1st to 15thNight
33%5%18%29%11%1
2340
16th to endNight
46%8%15%22%6%
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
20%221%32%18%5%
90
16th to endDay
15%316%25%27%12%
96
February1st to 15thDay
8%6%9%35%26%12%
134
16th to endDay
7%12%28%28%15%5%
238
March1st to 15thDay
7%10%22%30%23%5%
270
16th to endDay
14%15%25%26%15%2
288
April1st to 15thDay
9%17%25%23%16%7%
269
16th to endDay
10%24%22%24%15%1
270
May1st to 15thDay
5%10%29%28%20%5%
288
16th to endDay
8%9%19%26%24%12%
330
June1st to 15thDay
49%25%29%20%11%
315
16th to endDay
3320%30%29%13%
315
July1st to 15thDay
3120%27%28%17%
305
16th to endDay
4315%32%33%10%
327
August1st to 15thDay
4218%35%29%9%
315
16th to endDay
5%214%29%30%18%
332
September1st to 15thDay
45%15%34%24%15%
315
16th to endDay
47%17%24%32%13%
315
October1st to 15thDay
37%22%31%20%14%
207
16th to endDay
11%417%37%20%8%
96
November1st to 15thDay
6%5%131%28%26%
90
16th to endDay
10%5%20%45%15%3
90
December1st to 15thDay
8%10%20%44%15%1
90
16th to endDay
10%6%8%38%31%5%
96
January1st to 15thNight
7%413%39%29%5%
720
16th to endNight
8%214%38%27%7%
768
February1st to 15thNight
8%316%45%21%5%
704
16th to endNight
8%5%22%42%19%1
632
March1st to 15thNight
5%5%21%42%21%2
720
16th to endNight
7%8%25%37%18%2
768
April1st to 15thNight
8%10%28%31%19%1
692
16th to endNight
9%9%29%31%17%2
540
May1st to 15thNight
7%6%29%33%21%2
540
16th to endNight
8%6%19%33%29%2
563
June1st to 15thNight
5%6%20%41%25%1
540
16th to endNight
3222%40%28%1
540
July1st to 15thNight
6%111%39%38%3
510
16th to endNight
410%40%40%2
564
August1st to 15thNight
4117%45%29%1
539
16th to endNight
4110%36%40%5%
611
September1st to 15thNight
4111%37%38%6%
720
16th to endNight
4215%30%38%9%
716
October1st to 15thNight
6%315%40%27%6%
684
16th to endNight
4316%34%32%6%
704
November1st to 15thNight
7%215%38%30%5%
700
16th to endNight
4315%41%27%6%
720
December1st to 15thNight
8%416%44%21%3
720
16th to endNight
10%6%16%40%24%2
768
Page generated at 2017-10-07 12:07:49. Version ac04

Copyright 2017 A. Danko


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