High Point Ranch
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the High Point Ranch clear sky chart from 2005-11-05 to 2017-09-23.

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
73%
15509
34%
46959
30%
15470
78%
15470
49%
23153

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
73%
718
31%
2327
33%
716
76%
716
47%
1116
January16th to endNight
66%
768
35%
2496
35%
768
73%
768
39%
1315
February1st to 15thNight
70%
700
34%
2248
33%
699
77%
699
49%
1076
February16th to endNight
61%
632
38%
1808
32%
632
69%
632
46%
960
March1st to 15thNight
63%
720
39%
1980
28%
720
72%
720
53%
996
March16th to endNight
71%
768
38%
2112
26%
768
81%
768
59%
1015
April1st to 15thNight
64%
653
35%
1912
25%
653
74%
653
53%
917
April16th to endNight
67%
540
44%
1800
37%
540
80%
540
66%
678
May1st to 15thNight
70%
539
38%
1639
29%
539
80%
539
64%
689
May16th to endNight
72%
561
40%
1684
32%
561
77%
561
67%
707
June1st to 15thNight
81%
540
35%
1620
29%
540
82%
540
65%
697
June16th to endNight
83%
540
28%
1620
25%
540
84%
540
56%
753
July1st to 15thNight
78%
510
17%
1530
15%
510
78%
510
34%
899
July16th to endNight
76%
564
15%
1593
14%
531
75%
531
24%
1059
August1st to 15thNight
82%
539
22%
1611
21%
536
82%
536
35%
945
August16th to endNight
82%
573
28%
1875
30%
573
82%
573
37%
1031
September1st to 15thNight
76%
684
27%
1944
25%
684
77%
684
38%
1149
September16th to endNight
81%
688
41%
1903
31%
688
87%
688
64%
888
October1st to 15thNight
78%
660
39%
1941
32%
660
83%
660
60%
889
October16th to endNight
84%
704
43%
2112
36%
704
88%
704
66%
911
November1st to 15thNight
78%
700
42%
2100
35%
700
84%
700
64%
916
November16th to endNight
71%
720
38%
2268
35%
720
77%
720
50%
1087
December1st to 15thNight
70%
720
36%
2340
36%
720
75%
720
46%
1130
December16th to endNight
64%
768
34%
2496
33%
768
69%
768
38%
1330

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
321332445%6%62%
47940
Night
2213323346%64%
47157
TransparencyDay
21%46%13%28%25%
47635
Night
20%46%14%28%26%
46963
SeeingDay
5%11%24%33%20%5%
5361
Night
4313%36%34%7%
15518

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
3413423436%62%
1611
16th to endDay
6%5%23223245%60%
1728
February1st to 15thDay
3323312346%64%
1610
16th to endDay
3413423445%60%
1663
March1st to 15thDay
3313423446%63%
1980
16th to endDay
2212313245%70%
2112
April1st to 15thDay
1112323346%69%
2036
16th to endDay
111221123477%
2160
May1st to 15thDay
1111213345%74%
2308
16th to endDay
11122323476%
2429
June1st to 15thDay
111112335%76%
2340
16th to endDay
1112324445%68%
2340
July1st to 15thDay
4314436%6%8%10%44%
2340
16th to endDay
6%425%7%5%8%7%8%11%32%
2467
August1st to 15thDay
5%4247%47%7%7%9%39%
2340
16th to endDay
43145%35%6%7%9%46%
2327
September1st to 15thDay
5%5%24445%6%7%7%46%
2013
16th to endDay
2112313446%67%
1893
October1st to 15thDay
2112213436%70%
1687
16th to endDay
112222336%73%
1760
November1st to 15thDay
112211346%73%
1759
16th to endDay
221331233469%
1689
December1st to 15thDay
4314313446%62%
1620
16th to endDay
45%2441346%7%57%
1728
January1st to 15thNight
432332335%5%63%
2327
16th to endNight
5%5%24324345%58%
2496
February1st to 15thNight
231432335%6%65%
2239
16th to endNight
33143245%46%60%
1808
March1st to 15thNight
2312323346%66%
1980
16th to endNight
221213345%71%
2112
April1st to 15thNight
121322334469%
1912
16th to endNight
1111122481%
1800
May1st to 15thNight
111112345%75%
1639
16th to endNight
11111223479%
1684
June1st to 15thNight
211111213477%
1620
16th to endNight
1111225%346%68%
1620
July1st to 15thNight
2315%5%36%6%8%10%45%
1620
16th to endNight
3325%7%5%7%7%11%13%31%
1701
August1st to 15thNight
3223437%7%7%10%47%
1620
16th to endNight
2313435%6%8%11%48%
1875
September1st to 15thNight
45%24435%5%5%8%50%
1944
16th to endNight
1212212236%73%
1903
October1st to 15thNight
2113213225%73%
1941
16th to endNight
111211223478%
2112
November1st to 15thNight
112212246%73%
2100
16th to endNight
331222334467%
2268
December1st to 15thNight
4313312447%62%
2340
16th to endNight
4325%424346%56%
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
23%35%13%34%19%
1612
16th to endDay
26%2415%28%22%
1728
February1st to 15thDay
21%25%15%28%27%
1610
16th to endDay
25%2316%29%21%
1663
March1st to 15thDay
22%238%37%25%
1980
16th to endDay
17%2210%39%27%
2112
April1st to 15thDay
15%2311%39%27%
2036
16th to endDay
12%229%31%42%
2160
May1st to 15thDay
12%2311%32%37%
2308
16th to endDay
12%338%30%42%
2432
June1st to 15thDay
11%225%25%51%
2340
16th to endDay
17%348%20%44%
2340
July1st to 15thDay
29%10%14%16%14%14%
2201
16th to endDay
39%12%21%17%8%1
2312
August1st to 15thDay
36%9%11%16%18%7%
2325
16th to endDay
31%8%12%17%19%9%
2327
September1st to 15thDay
33%6%10%17%19%13%
2013
16th to endDay
17%3414%34%25%
1893
October1st to 15thDay
16%4413%30%30%
1687
16th to endDay
12%2412%33%33%
1760
November1st to 15thDay
12%1314%38%29%
1759
16th to endDay
19%2311%32%29%
1689
December1st to 15thDay
23%3420%31%17%
1620
16th to endDay
25%46%21%31%10%
1728
January1st to 15thNight
21%36%15%30%23%
2327
16th to endNight
27%3316%28%19%
2496
February1st to 15thNight
20%35%14%28%27%
2250
16th to endNight
22%4414%32%21%
1808
March1st to 15thNight
19%2311%33%29%
1980
16th to endNight
15%2314%40%24%
2112
April1st to 15thNight
18%1312%39%23%
1912
16th to endNight
9%1210%35%40%
1800
May1st to 15thNight
10%249%33%38%
1640
16th to endNight
10%2210%30%44%
1685
June1st to 15thNight
12%22422%56%
1620
16th to endNight
16%348%20%47%
1620
July1st to 15thNight
28%9%16%16%12%16%
1530
16th to endNight
36%13%20%21%5%2
1593
August1st to 15thNight
28%9%15%17%18%9%
1611
16th to endNight
25%8%15%18%19%11%
1875
September1st to 15thNight
28%7%11%20%18%13%
1944
16th to endNight
14%2415%36%26%
1903
October1st to 15thNight
15%25%17%28%31%
1941
16th to endNight
11%2314%28%38%
2112
November1st to 15thNight
13%1314%36%29%
2100
16th to endNight
20%3413%26%32%
2268
December1st to 15thNight
21%3418%32%19%
2340
16th to endNight
28%46%18%30%11%
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
14%14%22%37%10%1
90
16th to endDay
6%8%23%34%20%6%
96
February1st to 15thDay
313%19%37%23%3
125
16th to endDay
6%28%30%26%6%1
238
March1st to 15thDay
7%22%28%25%12%3
270
16th to endDay
327%32%20%12%3
288
April1st to 15thDay
5%26%33%22%8%4
269
16th to endDay
5%26%36%20%7%2
270
May1st to 15thDay
418%42%22%9%2
288
16th to endDay
313%35%35%10%2
330
June1st to 15thDay
27%36%32%16%3
315
16th to endDay
1227%35%26%5%
315
July1st to 15thDay
5%13%49%27%3
305
16th to endDay
6%11%36%29%14%
327
August1st to 15thDay
6%9%37%37%9%
315
16th to endDay
5%8%40%34%10%
332
September1st to 15thDay
9%212%42%27%5%
315
16th to endDay
5%6%26%35%20%4
284
October1st to 15thDay
1424%37%23%8%
127
16th to endDay
2316%36%39%2
96
November1st to 15thDay
313%18%34%25%4
90
16th to endDay
318%27%27%22%
90
December1st to 15thDay
18%21%36%28%3
90
16th to endDay
10%18%21%35%12%1
96
January1st to 15thNight
5%312%47%26%5%
720
16th to endNight
8%413%42%25%5%
768
February1st to 15thNight
35%14%42%28%4
704
16th to endNight
45%24%42%20%2
632
March1st to 15thNight
46%21%34%29%3
720
16th to endNight
26%16%37%31%5%
768
April1st to 15thNight
37%19%42%24%2
653
16th to endNight
17%22%41%22%5%
540
May1st to 15thNight
25%17%42%27%3
540
16th to endNight
2220%39%32%3
563
June1st to 15thNight
2111%44%36%3
540
16th to endNight
27%33%49%5%
540
July1st to 15thNight
6%426%53%10%
510
16th to endNight
4220%55%15%
564
August1st to 15thNight
3216%57%19%
539
16th to endNight
3317%55%19%
573
September1st to 15thNight
7%16%25%47%11%
684
16th to endNight
219%36%38%11%
688
October1st to 15thNight
3111%42%33%7%
660
16th to endNight
128%39%36%11%
704
November1st to 15thNight
2114%37%35%8%
700
16th to endNight
5%215%37%32%7%
720
December1st to 15thNight
8%313%40%28%5%
720
16th to endNight
6%5%16%44%20%7%
768
Page generated at 2017-09-24 06:15:50. Version ac04

Copyright 2017 A. Danko


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