Flying Horse Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Flying Horse Ranch clear sky chart from 2005-11-05 to 2018-01-12.

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
47%
16075
22%
48266
16%
16030
53%
16030
28%
30483

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
26%
956
18%
2662
9%
951
34%
951
22%
1852
January16th to endNight
24%
840
19%
2466
8%
840
33%
840
20%
1721
February1st to 15thNight
23%
704
17%
2112
8%
701
31%
701
18%
1494
February16th to endNight
24%
631
19%
1893
9%
631
32%
631
19%
1323
March1st to 15thNight
31%
720
18%
2160
11%
720
37%
720
21%
1449
March16th to endNight
35%
687
17%
2036
11%
687
40%
687
22%
1381
April1st to 15thNight
41%
539
24%
1797
17%
539
53%
539
31%
1029
April16th to endNight
47%
540
22%
1770
18%
540
54%
540
27%
1091
May1st to 15thNight
45%
540
18%
1619
12%
539
50%
539
26%
1067
May16th to endNight
65%
561
19%
1683
15%
561
68%
561
31%
1041
June1st to 15thNight
68%
540
20%
1496
15%
540
71%
540
40%
878
June16th to endNight
78%
540
24%
1440
19%
540
79%
540
42%
848
July1st to 15thNight
71%
510
17%
1360
15%
510
72%
510
34%
859
July16th to endNight
76%
564
22%
1523
20%
531
77%
531
39%
880
August1st to 15thNight
76%
539
22%
1729
23%
536
78%
536
37%
972
August16th to endNight
77%
573
23%
1910
27%
573
78%
573
34%
1060
September1st to 15thNight
66%
597
23%
1857
23%
597
68%
597
31%
1130
September16th to endNight
65%
717
31%
1980
25%
717
67%
717
37%
1170
October1st to 15thNight
59%
720
32%
1980
26%
720
64%
720
38%
1162
October16th to endNight
47%
768
29%
2411
23%
768
56%
768
32%
1417
November1st to 15thNight
47%
760
29%
2471
26%
760
56%
760
32%
1407
November16th to endNight
41%
780
27%
2535
21%
780
51%
780
28%
1504
December1st to 15thNight
32%
780
18%
2535
13%
780
39%
780
18%
1740
December16th to endNight
28%
969
19%
2841
10%
969
37%
969
20%
2008

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%6%25%5%3445%7%40%
49070
Night
13%6%25%424447%44%
48452
TransparencyDay
41%6%11%21%15%2
48759
Night
39%5%10%22%18%3
48268
SeeingDay
14%419%23%23%14%
6022
Night
16%6%22%30%20%2
16077

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
21%8%36%5%24445%33%
1520
16th to endDay
16%8%44434345%39%
1755
February1st to 15thDay
16%9%27%5%24346%36%
1750
16th to endDay
16%9%46%33445%6%34%
1580
March1st to 15thDay
20%9%35%323345%36%
1800
16th to endDay
16%7%36%6%35%45%6%34%
2195
April1st to 15thDay
13%5%26%5%34347%43%
2151
16th to endDay
14%5%35%5%35%445%41%
2190
May1st to 15thDay
18%5%25%425%45%8%37%
2331
16th to endDay
9%5%35%6%45%6%6%7%38%
2431
June1st to 15thDay
8%425%435%5%6%9%44%
2460
16th to endDay
5%3145%46%6%8%10%42%
2520
July1st to 15thDay
10%5%27%6%46%5%6%8%37%
2520
16th to endDay
8%324435%7%8%12%37%
2537
August1st to 15thDay
7%5%26%5%36%6%6%9%39%
2217
16th to endDay
9%425%6%445%6%9%40%
2292
September1st to 15thDay
13%5%25%5%45%5%6%7%37%
2091
16th to endDay
11%5%24423336%50%
1980
October1st to 15thDay
13%5%13423345%51%
1980
16th to endDay
14%423423335%52%
1811
November1st to 15thDay
14%6%13313436%50%
1717
16th to endDay
16%5%24323335%48%
1755
December1st to 15thDay
21%7%35%5%13445%37%
1755
16th to endDay
19%11%345%23445%35%
1732
January1st to 15thNight
18%9%36%424435%38%
2662
16th to endNight
18%10%26%5%24335%37%
2466
February1st to 15thNight
20%7%37%5%3334435%
2103
16th to endNight
17%8%46%5%24435%36%
1893
March1st to 15thNight
17%7%34434446%39%
2160
16th to endNight
15%7%46%5%24346%38%
2036
April1st to 15thNight
12%5%2332345%7%49%
1797
16th to endNight
13%4245%2346%8%43%
1770
May1st to 15thNight
14%6%35%5%3445%7%41%
1619
16th to endNight
6%3246%35%6%6%9%45%
1682
June1st to 15thNight
7%42441446%8%51%
1496
16th to endNight
3214425%6%6%12%50%
1440
July1st to 15thNight
9%324435%5%6%9%46%
1440
16th to endNight
6%214425%5%6%11%49%
1628
August1st to 15thNight
6%3134245%7%9%50%
1740
16th to endNight
6%3244345%6%9%49%
1910
September1st to 15thNight
13%415%32345%8%46%
1857
16th to endNight
10%424323436%53%
1980
October1st to 15thNight
11%5%13322445%55%
1980
16th to endNight
15%5%14313335%52%
2411
November1st to 15thNight
13%413413346%51%
2471
16th to endNight
15%7%23323236%49%
2535
December1st to 15thNight
19%9%36%42434436%
2535
16th to endNight
22%8%35%423335%36%
2841

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
52%37%21%12%2
1521
16th to endDay
46%49%26%11%1
1755
February1st to 15thDay
50%47%23%11%2
1752
16th to endDay
48%411%20%12%2
1580
March1st to 15thDay
50%39%19%14%2
1800
16th to endDay
49%6%11%23%8%
2196
April1st to 15thDay
40%5%9%22%19%2
2151
16th to endDay
43%49%24%15%2
2190
May1st to 15thDay
45%5%12%21%13%1
2331
16th to endDay
41%9%14%20%11%2
2435
June1st to 15thDay
34%9%13%24%16%1
2460
16th to endDay
31%9%14%20%19%4
2520
July1st to 15thDay
42%8%12%19%12%4
2371
16th to endDay
34%10%19%22%11%2
2380
August1st to 15thDay
38%9%13%21%16%1
2204
16th to endDay
37%8%12%21%17%3
2292
September1st to 15thDay
42%8%10%19%14%3
2091
16th to endDay
34%5%10%21%23%3
1980
October1st to 15thDay
34%5%9%24%22%4
1980
16th to endDay
35%36%22%26%4
1811
November1st to 15thDay
36%47%20%25%6%
1717
16th to endDay
38%37%27%20%3
1755
December1st to 15thDay
48%410%20%13%2
1755
16th to endDay
51%412%19%11%1
1732
January1st to 15thNight
48%38%19%16%2
2662
16th to endNight
50%49%20%13%2
2466
February1st to 15thNight
52%38%20%12%1
2112
16th to endNight
49%5%8%21%12%2
1893
March1st to 15thNight
46%49%19%14%4
2160
16th to endNight
46%5%11%23%11%1
2036
April1st to 15thNight
33%412%24%21%4
1797
16th to endNight
38%6%8%24%18%3
1770
May1st to 15thNight
42%5%11%23%15%1
1620
16th to endNight
32%10%17%21%15%3
1684
June1st to 15thNight
29%5%17%26%19%1
1496
16th to endNight
25%8%15%28%17%5%
1440
July1st to 15thNight
32%8%14%24%15%4
1360
16th to endNight
26%8%19%27%16%2
1523
August1st to 15thNight
26%8%16%25%20%2
1729
16th to endNight
29%7%14%25%19%3
1910
September1st to 15thNight
34%6%10%23%18%5%
1857
16th to endNight
31%5%8%21%26%7%
1980
October1st to 15thNight
31%48%21%28%6%
1980
16th to endNight
36%26%23%24%5%
2411
November1st to 15thNight
34%36%22%25%8%
2471
16th to endNight
37%37%24%22%3
2535
December1st to 15thNight
50%48%18%14%3
2535
16th to endNight
50%410%19%13%1
2841

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
30%12%36%12%5%2
123
16th to endDay
19%8%50%18%3
96
February1st to 15thDay
28%16%37%14%11
90
16th to endDay
24%11%38%16%9%
81
March1st to 15thDay
28%11%41%15%3
90
16th to endDay
17%9%30%29%9%2
282
April1st to 15thDay
14%11%25%29%14%4
270
16th to endDay
17%425%28%17%6%
270
May1st to 15thDay
18%10%22%27%12%9%
288
16th to endDay
12%220%25%23%14%
331
June1st to 15thDay
7%212%22%30%23%
435
16th to endDay
5%116%29%28%17%
495
July1st to 15thDay
13%212%29%26%16%
475
16th to endDay
9%418%34%34%
397
August1st to 15thDay
12%5%19%32%29%
313
16th to endDay
12%5%22%34%23%
332
September1st to 15thDay
14%16%20%34%21%
315
16th to endDay
13%311%19%35%17%
314
October1st to 15thDay
15%217%27%23%13%
315
16th to endDay
18%6%26%24%19%4
161
November1st to 15thDay
22%7%20%26%16%6%
135
16th to endDay
21%6%27%24%18%1
135
December1st to 15thDay
15%10%40%18%12%2
135
16th to endDay
26%11%46%13%1
144
January1st to 15thNight
21%14%31%25%5%
956
16th to endNight
24%9%36%25%3
840
February1st to 15thNight
24%13%33%24%3
704
16th to endNight
22%11%37%25%3
631
March1st to 15thNight
21%11%31%30%4
720
16th to endNight
18%10%28%31%10%
687
April1st to 15thNight
15%8%32%32%10%
539
16th to endNight
15%6%27%34%15%1
540
May1st to 15thNight
16%426%32%16%3
540
16th to endNight
8%214%37%31%5%
563
June1st to 15thNight
9%111%37%35%4
540
16th to endNight
49%39%41%5%
540
July1st to 15thNight
9%7%33%43%6%
510
16th to endNight
7%6%27%47%10%
564
August1st to 15thNight
7%431%46%8%
539
16th to endNight
6%15%33%45%7%
573
September1st to 15thNight
15%18%25%40%7%
597
16th to endNight
11%212%29%38%5%
717
October1st to 15thNight
15%316%33%25%5%
720
16th to endNight
17%5%25%30%19%2
768
November1st to 15thNight
16%6%25%29%18%3
760
16th to endNight
18%10%26%31%12%
780
December1st to 15thNight
24%9%26%28%10%
780
16th to endNight
26%9%30%28%5%
969
Page generated at 2018-01-12 21:01:30. Version ac04

Copyright 2018 A. Danko


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