Hill Town
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hill Town clear sky chart from 2005-11-05 to 2017-12-04.

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
49%
15788
23%
47727
18%
15744
55%
15744
30%
29277

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%
900
21%
2506
10%
895
36%
895
24%
1699
January16th to endNight
26%
798
22%
2385
11%
798
36%
798
22%
1592
February1st to 15thNight
25%
704
18%
2112
9%
701
34%
701
22%
1427
February16th to endNight
26%
631
22%
1893
11%
631
35%
631
21%
1267
March1st to 15thNight
30%
720
19%
2160
11%
720
36%
720
23%
1433
March16th to endNight
38%
678
20%
2032
13%
678
43%
678
26%
1317
April1st to 15thNight
43%
539
25%
1797
18%
539
55%
539
32%
993
April16th to endNight
46%
540
24%
1797
17%
540
56%
540
31%
1025
May1st to 15thNight
47%
539
20%
1620
13%
539
54%
539
29%
1029
May16th to endNight
65%
561
20%
1683
16%
561
67%
561
33%
1004
June1st to 15thNight
70%
540
21%
1542
17%
540
73%
540
39%
894
June16th to endNight
81%
540
25%
1440
20%
540
83%
540
46%
814
July1st to 15thNight
74%
510
17%
1360
15%
510
75%
510
37%
851
July16th to endNight
79%
564
21%
1554
20%
531
81%
531
40%
884
August1st to 15thNight
78%
539
21%
1774
24%
536
79%
536
36%
963
August16th to endNight
73%
573
22%
1910
26%
573
74%
573
30%
1133
September1st to 15thNight
65%
594
23%
1854
22%
594
67%
594
32%
1124
September16th to endNight
64%
717
30%
1980
24%
717
67%
717
38%
1169
October1st to 15thNight
59%
720
33%
1980
27%
720
64%
720
39%
1150
October16th to endNight
52%
768
33%
2386
27%
768
60%
768
35%
1356
November1st to 15thNight
49%
760
30%
2471
26%
760
57%
760
32%
1391
November16th to endNight
43%
780
29%
2535
23%
780
53%
780
30%
1479
December1st to 15thNight
37%
736
21%
2391
15%
736
45%
736
22%
1548
December16th to endNight
30%
837
20%
2565
12%
837
38%
837
21%
1735

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
13%5%25%5%35%5%5%7%40%
48759
Night
12%5%25%42445%7%45%
47914
TransparencyDay
41%411%22%16%3
48449
Night
37%410%23%19%4
47728
SeeingDay
14%416%24%24%15%
5824
Night
15%6%22%30%21%3
15791

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
20%7%25%5%24436%37%
1432
16th to endDay
18%6%25%5%13345%43%
1833
February1st to 15thDay
18%9%35%5%23335%38%
1750
16th to endDay
16%7%36%6%34447%36%
1580
March1st to 15thDay
19%8%26%424445%36%
1800
16th to endDay
15%6%37%6%345%5%7%34%
2199
April1st to 15thDay
12%5%24434446%45%
2151
16th to endDay
14%6%25%5%345%5%7%39%
2162
May1st to 15thDay
16%6%35%5%34447%39%
2331
16th to endDay
10%6%26%6%35%46%8%38%
2431
June1st to 15thDay
6%5%25%5%45%6%6%10%40%
2415
16th to endDay
5%2246%47%6%7%10%41%
2520
July1st to 15thDay
9%426%7%47%7%7%10%33%
2520
16th to endDay
6%425%6%5%7%7%8%11%34%
2504
August1st to 15thDay
6%425%7%36%6%9%9%37%
2173
16th to endDay
10%5%36%6%46%6%6%8%36%
2292
September1st to 15thDay
12%5%25%6%35%5%7%7%37%
2093
16th to endDay
10%325%5%24447%49%
1980
October1st to 15thDay
12%5%15%433347%48%
1980
16th to endDay
14%31332333454%
1834
November1st to 15thDay
14%5%23223245%51%
1717
16th to endDay
16%5%23224346%49%
1755
December1st to 15thDay
21%7%45%424345%36%
1651
16th to endDay
20%9%25%323246%37%
1656
January1st to 15thNight
18%9%26%42334440%
2506
16th to endNight
18%7%26%5%2445%439%
2385
February1st to 15thNight
17%9%35%5%23445%38%
2103
16th to endNight
17%6%45%5%3435%5%38%
1893
March1st to 15thNight
16%6%36%5%24446%39%
2160
16th to endNight
12%6%35%5%3445%7%40%
2032
April1st to 15thNight
11%5%1432335%7%50%
1797
16th to endNight
11%5%2432446%6%48%
1797
May1st to 15thNight
10%6%35%5%35%35%6%44%
1619
16th to endNight
6%4245%345%5%10%46%
1682
June1st to 15thNight
43245%346%6%10%47%
1542
16th to endNight
2213335%5%7%14%50%
1440
July1st to 15thNight
8%325%435%5%8%11%41%
1440
16th to endNight
42135%25%6%8%12%46%
1661
August1st to 15thNight
4214435%5%8%11%47%
1785
16th to endNight
6%425%4246%7%11%42%
1910
September1st to 15thNight
11%4244245%5%7%45%
1854
16th to endNight
8%5%23424446%53%
1980
October1st to 15thNight
9%5%14432346%54%
1980
16th to endNight
13%423312345%53%
2386
November1st to 15thNight
11%424423346%51%
2471
16th to endNight
15%6%24322335%50%
2535
December1st to 15thNight
17%8%35%433346%39%
2391
16th to endNight
22%8%25%424435%37%
2565

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
47%36%22%16%2
1433
16th to endDay
43%39%25%16%1
1833
February1st to 15thDay
49%27%22%14%3
1752
16th to endDay
48%29%22%13%3
1580
March1st to 15thDay
49%48%17%15%4
1800
16th to endDay
47%5%11%22%12%
2200
April1st to 15thDay
38%310%22%20%4
2151
16th to endDay
41%49%24%17%3
2162
May1st to 15thDay
45%310%21%15%2
2331
16th to endDay
41%5%14%23%12%2
2435
June1st to 15thDay
35%6%13%26%16%1
2415
16th to endDay
34%7%12%21%19%4
2520
July1st to 15thDay
41%7%16%18%11%4
2371
16th to endDay
39%7%17%23%10%1
2348
August1st to 15thDay
36%8%15%21%15%2
2160
16th to endDay
41%6%13%21%14%2
2292
September1st to 15thDay
41%6%12%21%13%4
2093
16th to endDay
34%311%22%23%3
1980
October1st to 15thDay
36%27%24%23%5%
1980
16th to endDay
33%25%21%29%7%
1834
November1st to 15thDay
36%25%20%27%7%
1717
16th to endDay
36%26%26%22%4
1755
December1st to 15thDay
50%26%21%14%3
1651
16th to endDay
48%311%20%13%2
1656
January1st to 15thNight
46%37%21%18%3
2506
16th to endNight
47%37%20%17%3
2385
February1st to 15thNight
48%210%21%14%2
2112
16th to endNight
47%37%22%16%2
1893
March1st to 15thNight
45%38%18%17%5%
2160
16th to endNight
42%312%24%14%1
2032
April1st to 15thNight
33%211%25%21%5%
1797
16th to endNight
34%310%25%21%3
1797
May1st to 15thNight
39%412%22%18%2
1620
16th to endNight
32%7%16%24%15%3
1684
June1st to 15thNight
28%6%16%27%17%2
1542
16th to endNight
22%7%17%28%18%4
1440
July1st to 15thNight
31%8%18%23%15%4
1360
16th to endNight
26%7%20%29%14%2
1554
August1st to 15thNight
27%7%17%26%18%2
1774
16th to endNight
34%6%14%24%15%3
1910
September1st to 15thNight
36%5%14%22%17%4
1854
16th to endNight
31%49%22%24%6%
1980
October1st to 15thNight
30%37%22%27%7%
1980
16th to endNight
33%2323%27%8%
2386
November1st to 15thNight
33%36%20%25%10%
2471
16th to endNight
37%26%21%26%5%
2535
December1st to 15thNight
45%38%20%17%4
2391
16th to endNight
49%210%19%16%2
2565

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
25%8%42%10%12%1
90
16th to endDay
21%11%43%17%5%
96
February1st to 15thDay
23%15%40%15%41
90
16th to endDay
25%17%27%20%7%1
81
March1st to 15thDay
24%16%33%21%31
90
16th to endDay
17%8%28%30%13%2
276
April1st to 15thDay
15%10%22%32%14%4
270
16th to endDay
17%421%32%18%6%
270
May1st to 15thDay
15%9%20%27%17%9%
288
16th to endDay
16%216%25%23%15%
331
June1st to 15thDay
8%112%19%31%26%
390
16th to endDay
6%211%27%31%20%
495
July1st to 15thDay
10%19%31%30%15%
475
16th to endDay
6%16%15%29%40%
364
August1st to 15thDay
9%1421%34%27%
313
16th to endDay
13%1320%41%19%
332
September1st to 15thDay
13%35%20%31%24%
315
16th to endDay
11%29%26%33%16%
314
October1st to 15thDay
14%219%26%26%11%
315
16th to endDay
17%5%22%27%20%6%
163
November1st to 15thDay
24%5%22%28%14%3
135
16th to endDay
20%5%31%20%18%4
135
December1st to 15thDay
20%8%36%22%11%3
100
16th to endDay
18%11%45%18%41
96
January1st to 15thNight
22%13%32%25%6%
900
16th to endNight
21%9%38%27%2
798
February1st to 15thNight
23%11%35%25%3
704
16th to endNight
22%13%34%27%2
631
March1st to 15thNight
21%11%32%28%5%
720
16th to endNight
15%9%30%30%11%1
678
April1st to 15thNight
12%10%31%33%11%1
539
16th to endNight
12%6%30%35%14%
540
May1st to 15thNight
12%427%34%20%1
540
16th to endNight
8%113%39%33%4
563
June1st to 15thNight
6%112%34%38%6%
540
16th to endNight
37%36%43%8%
540
July1st to 15thNight
8%16%30%43%9%
510
16th to endNight
46%26%48%13%
564
August1st to 15thNight
6%331%48%10%
539
16th to endNight
8%333%46%7%
573
September1st to 15thNight
12%29%28%40%6%
594
16th to endNight
11%112%29%39%5%
717
October1st to 15thNight
12%317%31%29%4
720
16th to endNight
15%422%33%21%2
768
November1st to 15thNight
14%6%23%32%19%3
760
16th to endNight
18%8%26%30%15%
780
December1st to 15thNight
20%11%26%30%10%
736
16th to endNight
26%7%30%29%5%
837
Page generated at 2017-12-05 09:19:04. Version ac04

Copyright 2017 A. Danko


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