Shenandoah County Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Shenandoah County Park clear sky chart from 2005-11-05 to 2018-08-29.

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
40%
16493
20%
50665
12%
16455
50%
16455
23%
32309

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
25%
777
20%
2545
8%
776
40%
776
17%
1619
January16th to endNight
21%
832
21%
2704
7%
832
38%
832
18%
1732
February1st to 15thNight
24%
762
18%
2482
7%
761
38%
761
18%
1575
February16th to endNight
19%
683
20%
2088
6%
683
35%
683
16%
1397
March1st to 15thNight
26%
780
21%
2145
9%
780
38%
780
22%
1391
March16th to endNight
26%
832
18%
2288
9%
832
34%
832
20%
1540
April1st to 15thNight
25%
778
18%
1962
5%
778
33%
778
23%
1354
April16th to endNight
38%
745
18%
1901
8%
745
43%
745
27%
1295
May1st to 15thNight
42%
585
17%
1755
9%
585
47%
585
23%
1176
May16th to endNight
51%
467
16%
1686
13%
467
55%
467
23%
1058
June1st to 15thNight
55%
390
19%
1560
19%
390
63%
390
23%
945
June16th to endNight
61%
390
18%
1560
20%
390
67%
390
24%
898
July1st to 15thNight
59%
446
13%
1556
14%
446
62%
446
23%
980
July16th to endNight
73%
612
16%
1739
12%
579
76%
579
35%
1046
August1st to 15thNight
69%
575
18%
1715
15%
572
70%
572
29%
1110
August16th to endNight
67%
762
19%
1992
14%
762
68%
762
32%
1302
September1st to 15thNight
60%
720
24%
1800
14%
720
63%
720
33%
1189
September16th to endNight
54%
717
23%
2005
19%
717
58%
717
30%
1279
October1st to 15thNight
49%
720
22%
2160
19%
720
55%
720
27%
1353
October16th to endNight
39%
768
29%
2304
17%
768
56%
768
30%
1338
November1st to 15thNight
42%
760
25%
2346
17%
760
53%
760
26%
1439
November16th to endNight
34%
780
22%
2730
13%
780
48%
780
20%
1627
December1st to 15thNight
31%
780
17%
2730
8%
780
43%
780
16%
1788
December16th to endNight
29%
832
20%
2912
9%
832
44%
832
17%
1878

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%39%
51570
Night
12%5%25%43445%7%43%
50854
Cloud CoverDay
13%5%25%5%35%5%5%7%40%
51580
Night
12%5%25%42445%7%43%
50858
TransparencyDay
42%8%12%20%14%2
51277
Night
38%7%12%22%15%2
50665
SeeingDay
18%11%23%22%16%6%
6803
Night
16%11%25%30%14%1
16499

By Month

Percentage Cloud Cover NE (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
11%6%45%5%45%5%5%7%38%
1720
16th to endDay
12%6%36%6%25%446%40%
1872
February1st to 15thDay
11%8%37%5%25%5%5%6%37%
1710
16th to endDay
13%8%35%5%34445%40%
1669
March1st to 15thDay
13%7%25%5%25%435%45%
2134
16th to endDay
14%7%46%425%5%5%7%37%
2288
April1st to 15thDay
11%6%35%5%25%5%5%7%42%
2315
16th to endDay
15%5%3443445%6%42%
2344
May1st to 15thDay
17%6%25%5%35%5%5%8%35%
2526
16th to endDay
15%5%36%6%45%5%5%7%36%
2780
June1st to 15thDay
11%3246%45%5%6%9%38%
2730
16th to endDay
9%325%7%46%6%6%9%38%
2730
July1st to 15thDay
9%5%36%6%46%5%6%8%37%
2645
16th to endDay
8%436%6%46%7%7%9%33%
2673
August1st to 15thDay
10%6%25%7%46%7%7%8%32%
2487
16th to endDay
11%5%26%6%36%6%7%8%36%
2492
September1st to 15thDay
13%5%145%445%5%6%43%
2160
16th to endDay
15%5%15%5%3445%6%40%
1953
October1st to 15thDay
18%5%2432335%6%44%
1800
16th to endDay
13%5%2443335%6%47%
1920
November1st to 15thDay
11%5%25%32345%5%48%
1838
16th to endDay
15%5%244245%46%43%
1560
December1st to 15thDay
14%6%35%435%5%5%6%40%
1560
16th to endDay
15%7%35%5%445%5%6%38%
1664
January1st to 15thNight
12%6%24435%45%6%43%
2545
16th to endNight
13%8%345%2345%7%42%
2704
February1st to 15thNight
11%7%25%5%3446%7%41%
2480
16th to endNight
11%7%25%6%25%6%6%6%39%
2088
March1st to 15thNight
13%5%24425%45%6%44%
2133
16th to endNight
14%6%25%4245%46%42%
2288
April1st to 15thNight
11%5%36%5%25%45%7%40%
1962
16th to endNight
13%5%3442445%6%44%
1901
May1st to 15thNight
14%6%26%5%34446%40%
1755
16th to endNight
13%435%43345%8%43%
1684
June1st to 15thNight
9%5%235%35%5%6%8%44%
1560
16th to endNight
7%425%435%5%7%9%44%
1560
July1st to 15thNight
9%425%5%35%6%6%9%41%
1642
16th to endNight
5%3144346%8%13%43%
1847
August1st to 15thNight
7%5%245%36%6%6%8%43%
1726
16th to endNight
8%424435%5%7%10%43%
1992
September1st to 15thNight
12%42443445%7%46%
1800
16th to endNight
13%5%24434338%46%
2005
October1st to 15thNight
17%42432445%6%45%
2160
16th to endNight
12%323323437%53%
2304
November1st to 15thNight
12%6%34323436%49%
2346
16th to endNight
12%43442446%7%45%
2730
December1st to 15thNight
13%6%36%5%35%5%45%39%
2730
16th to endNight
12%5%26%5%35%5%5%7%39%
2912

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
12%5%346%35%5%5%7%38%
1720
16th to endDay
12%7%36%6%235%46%41%
1872
February1st to 15thDay
11%8%37%435%5%5%7%37%
1710
16th to endDay
13%8%36%5%345%46%40%
1669
March1st to 15thDay
13%7%25%5%24445%45%
2145
16th to endDay
14%7%45%42445%7%37%
2287
April1st to 15thDay
11%6%35%5%25%447%43%
2315
16th to endDay
15%6%245%2435%6%42%
2344
May1st to 15thDay
17%6%25%5%35%45%8%35%
2526
16th to endDay
15%5%36%6%35%5%5%7%36%
2780
June1st to 15thDay
11%4245%46%5%6%9%40%
2730
16th to endDay
9%425%6%46%6%6%9%38%
2730
July1st to 15thDay
10%5%35%6%46%5%6%9%37%
2645
16th to endDay
9%425%6%47%7%6%9%34%
2673
August1st to 15thDay
11%5%26%7%46%6%8%8%32%
2487
16th to endDay
10%5%25%6%46%6%7%8%36%
2492
September1st to 15thDay
13%415%435%5%5%6%44%
2160
16th to endDay
15%5%245%4445%6%40%
1953
October1st to 15thDay
18%5%14323346%45%
1800
16th to endDay
12%6%145%2335%6%48%
1920
November1st to 15thDay
11%6%25%424445%48%
1838
16th to endDay
15%4244245%36%45%
1560
December1st to 15thDay
14%5%25%4345%46%40%
1560
16th to endDay
15%7%246%35%45%6%38%
1664
January1st to 15thNight
12%6%25%435%5%47%43%
2545
16th to endNight
13%9%2442345%6%42%
2704
February1st to 15thNight
11%6%25%5%25%46%6%41%
2473
16th to endNight
11%7%25%6%246%6%6%39%
2088
March1st to 15thNight
13%5%244245%5%6%45%
2145
16th to endNight
15%5%25%5%2445%6%42%
2288
April1st to 15thNight
10%6%26%5%3446%7%41%
1962
16th to endNight
13%5%24435%45%7%44%
1901
May1st to 15thNight
14%5%26%43435%7%40%
1754
16th to endNight
13%5%25%434448%43%
1684
June1st to 15thNight
9%424435%5%6%8%44%
1560
16th to endNight
7%325%5%245%7%9%44%
1560
July1st to 15thNight
9%415%5%35%5%6%8%42%
1642
16th to endNight
5%313425%6%8%13%44%
1847
August1st to 15thNight
7%425%5%36%6%6%9%43%
1726
16th to endNight
8%424435%5%7%10%42%
1992
September1st to 15thNight
11%5%245%3445%7%46%
1800
16th to endNight
13%424434347%46%
2005
October1st to 15thNight
17%324423347%45%
2160
16th to endNight
12%313324346%54%
2304
November1st to 15thNight
11%6%34313435%49%
2346
16th to endNight
12%425%42445%7%45%
2730
December1st to 15thNight
13%7%26%5%35%5%5%5%39%
2730
16th to endNight
12%5%37%5%25%5%6%7%39%
2912

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
42%7%12%18%15%3
1721
16th to endDay
43%6%11%21%14%2
1872
February1st to 15thDay
45%7%11%19%13%2
1712
16th to endDay
43%5%12%23%12%1
1669
March1st to 15thDay
42%49%23%15%3
2145
16th to endDay
45%8%10%16%15%2
2288
April1st to 15thDay
40%6%11%20%16%4
2315
16th to endDay
42%7%9%18%17%5%
2344
May1st to 15thDay
45%8%13%19%12%1
2526
16th to endDay
45%9%12%20%10%2
2784
June1st to 15thDay
39%9%14%21%13%1
2730
16th to endDay
39%11%14%19%13%2
2730
July1st to 15thDay
41%10%12%18%13%3
2502
16th to endDay
41%10%13%20%12%2
2518
August1st to 15thDay
45%11%13%17%12%
2474
16th to endDay
41%11%14%20%10%1
2492
September1st to 15thDay
39%7%11%18%19%2
2160
16th to endDay
43%6%9%21%16%1
1953
October1st to 15thDay
39%6%11%24%14%4
1800
16th to endDay
36%5%9%25%19%2
1920
November1st to 15thDay
37%5%10%20%20%5%
1838
16th to endDay
39%5%10%24%18%1
1560
December1st to 15thDay
43%7%13%20%12%2
1560
16th to endDay
46%6%12%21%11%1
1664
January1st to 15thNight
40%6%12%17%17%5%
2545
16th to endNight
41%6%11%22%16%1
2704
February1st to 15thNight
40%6%12%22%14%2
2482
16th to endNight
43%6%11%23%12%1
2088
March1st to 15thNight
38%6%12%26%12%2
2145
16th to endNight
41%7%12%20%15%1
2288
April1st to 15thNight
40%8%10%22%15%2
1962
16th to endNight
39%7%10%20%16%5%
1901
May1st to 15thNight
42%7%12%22%11%3
1755
16th to endNight
39%8%16%21%12%1
1686
June1st to 15thNight
36%10%12%26%13%1
1560
16th to endNight
33%9%15%22%17%1
1560
July1st to 15thNight
37%10%15%20%12%4
1556
16th to endNight
26%12%19%25%15%1
1739
August1st to 15thNight
35%9%14%24%14%
1715
16th to endNight
33%10%14%26%13%1
1992
September1st to 15thNight
36%7%14%19%19%2
1800
16th to endNight
38%5%9%25%19%1
2005
October1st to 15thNight
38%5%11%23%18%2
2160
16th to endNight
31%5%9%28%22%2
2304
November1st to 15thNight
37%5%8%21%19%7%
2346
16th to endNight
37%5%10%23%19%3
2730
December1st to 15thNight
45%6%11%21%12%1
2730
16th to endNight
43%6%14%21%12%1
2912

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
23%31%24%13%6%
129
16th to endDay
29%29%27%12%1
144
February1st to 15thDay
30%27%37%3
135
16th to endDay
27%19%34%16%2
214
March1st to 15thDay
24%23%24%22%5%
330
16th to endDay
24%17%29%20%5%2
352
April1st to 15thDay
18%20%26%22%9%2
330
16th to endDay
21%11%28%19%13%5%
319
May1st to 15thDay
23%15%24%18%11%5%
348
16th to endDay
21%7%23%21%19%6%
395
June1st to 15thDay
16%8%23%25%20%6%
375
16th to endDay
12%7%29%26%18%5%
375
July1st to 15thDay
12%225%32%18%9%
365
16th to endDay
11%216%31%26%11%
390
August1st to 15thDay
13%217%24%27%13%
358
16th to endDay
9%215%28%24%19%
384
September1st to 15thDay
15%7%15%20%25%14%
315
16th to endDay
20%417%22%21%14%
314
October1st to 15thDay
21%5%15%28%23%5%
315
16th to endDay
12%19%27%21%15%3
336
November1st to 15thDay
20%9%24%26%15%3
304
16th to endDay
24%15%30%21%8%
90
December1st to 15thDay
25%22%26%15%8%1
90
16th to endDay
21%25%38%12%2
96
January1st to 15thNight
20%18%30%24%5%
780
16th to endNight
21%17%34%24%1
832
February1st to 15thNight
19%18%32%27%1
764
16th to endNight
22%22%32%20%2
683
March1st to 15thNight
21%17%32%24%3
780
16th to endNight
19%18%32%22%6%1
832
April1st to 15thNight
16%19%35%22%5%
778
16th to endNight
17%11%27%28%12%
745
May1st to 15thNight
17%7%26%31%16%1
585
16th to endNight
16%321%32%23%1
468
June1st to 15thNight
10%222%36%25%2
390
16th to endNight
5%319%46%23%1
390
July1st to 15thNight
11%114%38%30%3
446
16th to endNight
7%10%41%34%6%
612
August1st to 15thNight
9%111%44%29%4
575
16th to endNight
10%110%38%33%4
762
September1st to 15thNight
13%316%30%31%4
720
16th to endNight
14%5%17%29%29%3
717
October1st to 15thNight
20%8%17%28%22%2
720
16th to endNight
15%13%27%28%13%1
768
November1st to 15thNight
15%13%23%32%13%1
760
16th to endNight
18%17%25%27%9%
780
December1st to 15thNight
19%14%28%29%7%
780
16th to endNight
17%15%31%33%1
832
Page generated at 2018-08-30 05:34:21. Version ac04

Copyright 2018 A. Danko


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