Henry Coe State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Henry Coe State Park clear sky chart from 2005-11-05 to 2017-08-12.

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
68%
15281
27%
46536
24%
15245
71%
15245
41%
24972

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
65%
716
19%
2395
20%
716
67%
716
31%
1376
January16th to endNight
60%
768
24%
2496
26%
768
62%
768
28%
1511
February1st to 15thNight
60%
698
25%
2264
26%
698
65%
698
28%
1357
February16th to endNight
55%
632
23%
1895
20%
632
61%
632
31%
1162
March1st to 15thNight
55%
720
18%
2028
17%
720
58%
720
30%
1309
March16th to endNight
52%
768
21%
2073
15%
768
57%
768
31%
1326
April1st to 15thNight
51%
719
23%
1799
13%
719
55%
719
33%
1162
April16th to endNight
57%
720
26%
1800
12%
720
61%
720
46%
1026
May1st to 15thNight
69%
657
25%
1737
16%
657
72%
657
51%
922
May16th to endNight
69%
376
26%
1498
26%
376
75%
376
41%
655
June1st to 15thNight
73%
360
27%
1440
28%
360
81%
360
42%
627
June16th to endNight
86%
360
35%
1440
44%
360
89%
360
61%
504
July1st to 15thNight
91%
365
32%
1385
39%
365
92%
365
66%
483
July16th to endNight
89%
564
33%
1593
30%
531
90%
531
59%
716
August1st to 15thNight
85%
570
32%
1619
25%
567
86%
567
58%
761
August16th to endNight
91%
700
38%
1750
24%
700
91%
700
72%
830
September1st to 15thNight
89%
660
42%
1650
31%
660
90%
660
76%
774
September16th to endNight
83%
656
39%
1784
37%
656
84%
656
61%
860
October1st to 15thNight
71%
660
30%
1980
31%
660
76%
660
47%
1007
October16th to endNight
73%
704
34%
2112
36%
704
77%
704
48%
1067
November1st to 15thNight
70%
700
30%
2199
30%
700
74%
700
45%
1111
November16th to endNight
65%
720
27%
2391
26%
720
69%
720
36%
1292
December1st to 15thNight
56%
720
22%
2520
20%
720
63%
720
26%
1520
December16th to endNight
49%
768
21%
2688
19%
768
56%
768
24%
1614

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
7%313213335%62%
47431
Night
8%413313347%57%
46724
TransparencyDay
24%49%18%24%18%
47117
Night
26%410%19%22%17%
46537
SeeingDay
9%9%22%34%19%4
5853
Night
8%312%32%32%9%
15293

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
14%5%24423345%48%
1540
16th to endDay
17%6%25%323245%45%
1728
February1st to 15thDay
17%7%24413345%44%
1600
16th to endDay
20%6%35%425%336%37%
1579
March1st to 15thDay
14%7%25%5%35%46%8%36%
1929
16th to endDay
13%6%25%4345%47%42%
2151
April1st to 15thDay
15%6%35%413447%43%
2149
16th to endDay
7%413223336%60%
2160
May1st to 15thDay
3313212347%65%
2211
16th to endDay
4323322346%61%
2610
June1st to 15thDay
3312212346%67%
2520
16th to endDay
1111121483%
2520
July1st to 15thDay
1111122483%
2490
16th to endDay
11222483%
2468
August1st to 15thDay
1111122482%
2246
16th to endDay
11122484%
2100
September1st to 15thDay
111111484%
1980
16th to endDay
212112245%75%
1841
October1st to 15thDay
4313323337%63%
1650
16th to endDay
6%413323345%62%
1760
November1st to 15thDay
8%413424447%54%
1657
16th to endDay
12%6%2332335%5%52%
1566
December1st to 15thDay
17%6%35%5%2432443%
1440
16th to endDay
17%7%25%422346%41%
1536
January1st to 15thNight
12%42432445%8%47%
2395
16th to endNight
17%5%24312347%47%
2496
February1st to 15thNight
15%5%24324447%44%
2253
16th to endNight
16%6%2332335%7%44%
1895
March1st to 15thNight
13%6%33424447%44%
2028
16th to endNight
12%6%25%22435%8%46%
2073
April1st to 15thNight
12%5%235%2445%7%46%
1799
16th to endNight
5%323324247%59%
1800
May1st to 15thNight
221221345%9%62%
1737
16th to endNight
332322335%8%62%
1498
June1st to 15thNight
2212323347%67%
1440
16th to endNight
11311245%77%
1440
July1st to 15thNight
1112437%76%
1467
16th to endNight
1221335%7%69%
1701
August1st to 15thNight
112313448%67%
1628
16th to endNight
1113435%76%
1750
September1st to 15thNight
1122213479%
1650
16th to endNight
221211222475%
1784
October1st to 15thNight
5%423222237%62%
1980
16th to endNight
5%313313345%63%
2112
November1st to 15thNight
7%412213347%59%
2199
16th to endNight
8%5%24324447%54%
2391
December1st to 15thNight
15%6%24323346%46%
2520
16th to endNight
19%5%24323346%45%
2688

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
37%5%12%19%16%9%
1540
16th to endDay
41%6%7%14%18%12%
1728
February1st to 15thDay
40%49%20%18%6%
1600
16th to endDay
46%5%9%21%13%3
1579
March1st to 15thDay
42%7%10%16%16%5%
1929
16th to endDay
38%9%13%18%16%3
2151
April1st to 15thDay
39%411%20%19%3
2149
16th to endDay
24%6%12%24%23%8%
2160
May1st to 15thDay
16%412%26%30%8%
2211
16th to endDay
22%6%13%25%24%7%
2614
June1st to 15thDay
18%5%11%22%25%16%
2520
16th to endDay
8%15%18%33%32%
2520
July1st to 15thDay
7%249%25%51%
2343
16th to endDay
7%3410%26%47%
2313
August1st to 15thDay
9%15%14%28%41%
2230
16th to endDay
6%1415%35%36%
2100
September1st to 15thDay
7%1414%33%38%
1980
16th to endDay
12%26%23%34%20%
1841
October1st to 15thDay
19%48%23%25%19%
1650
16th to endDay
24%39%20%25%16%
1760
November1st to 15thDay
28%6%10%23%22%8%
1657
16th to endDay
32%5%10%18%27%4
1566
December1st to 15thDay
43%5%11%14%20%5%
1440
16th to endDay
43%412%17%16%5%
1536
January1st to 15thNight
33%5%13%19%18%8%
2395
16th to endNight
36%6%10%13%17%15%
2496
February1st to 15thNight
37%411%20%18%8%
2264
16th to endNight
36%414%24%14%4
1895
March1st to 15thNight
37%6%13%18%15%8%
2028
16th to endNight
36%6%13%18%17%8%
2073
April1st to 15thNight
34%6%13%23%18%4
1799
16th to endNight
23%5%13%25%22%10%
1800
May1st to 15thNight
18%6%13%20%27%13%
1738
16th to endNight
17%6%15%24%27%8%
1498
June1st to 15thNight
18%6%11%20%22%22%
1440
16th to endNight
11%2416%28%37%
1440
July1st to 15thNight
9%2411%24%47%
1385
16th to endNight
14%35%18%18%39%
1593
August1st to 15thNight
17%25%18%23%33%
1619
16th to endNight
10%26%14%32%32%
1750
September1st to 15thNight
9%15%11%28%43%
1650
16th to endNight
15%35%16%33%25%
1784
October1st to 15thNight
22%39%22%21%21%
1980
16th to endNight
21%39%22%24%18%
2112
November1st to 15thNight
23%412%22%26%10%
2199
16th to endNight
28%5%9%22%24%9%
2391
December1st to 15thNight
38%5%10%16%19%8%
2520
16th to endNight
39%413%16%18%7%
2688

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
24%7%25%27%11%3
168
16th to endDay
21%7%19%28%18%3
256
February1st to 15thDay
20%8%21%26%20%1
241
16th to endDay
18%14%26%24%14%2
238
March1st to 15thDay
18%16%24%22%15%4
270
16th to endDay
15%17%30%25%10%1
288
April1st to 15thDay
18%20%27%22%9%
269
16th to endDay
10%22%29%27%8%1
270
May1st to 15thDay
7%13%36%31%8%2
288
16th to endDay
6%13%25%33%17%4
330
June1st to 15thDay
5%11%33%33%11%4
315
16th to endDay
1221%43%23%6%
315
July1st to 15thDay
11%48%32%6%
305
16th to endDay
110%52%24%11%
327
August1st to 15thDay
3214%42%32%6%
300
16th to endDay
114%46%29%8%
268
September1st to 15thDay
1213%45%29%7%
255
16th to endDay
45%16%37%27%7%
255
October1st to 15thDay
6%9%21%39%19%3
255
16th to endDay
10%426%34%23%1
272
November1st to 15thDay
9%7%15%23%32%10%
163
16th to endDay
9%8%25%35%17%2
81
December1st to 15thDay
25%10%23%33%8%
60
16th to endDay
12%14%10%31%25%6%
64
January1st to 15thNight
13%211%32%26%12%
720
16th to endNight
16%410%31%25%12%
768
February1st to 15thNight
17%311%32%25%9%
704
16th to endNight
17%5%15%34%20%6%
632
March1st to 15thNight
13%5%16%28%28%6%
720
16th to endNight
13%6%20%31%23%4
768
April1st to 15thNight
11%9%19%34%21%4
719
16th to endNight
5%7%22%32%23%7%
720
May1st to 15thNight
3220%39%27%6%
658
16th to endNight
2417%37%32%5%
377
June1st to 15thNight
2315%42%32%4
360
16th to endNight
7%43%43%4
360
July1st to 15thNight
1232%53%10%
365
16th to endNight
1227%51%16%
564
August1st to 15thNight
15%36%47%9%
570
16th to endNight
433%50%11%
700
September1st to 15thNight
1429%50%13%
660
16th to endNight
39%29%41%15%
656
October1st to 15thNight
5%312%31%31%15%
660
16th to endNight
7%110%30%29%20%
704
November1st to 15thNight
6%213%33%30%13%
700
16th to endNight
8%215%31%30%12%
720
December1st to 15thNight
16%312%32%26%7%
720
16th to endNight
19%6%17%29%22%5%
768
Page generated at 2017-08-13 11:16:26. Version ac04

Copyright 2017 A. Danko


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