Leasburg Dam State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Leasburg Dam State Park clear sky chart from 2005-11-05 to 2017-10-06.

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
67%
15408
34%
47276
26%
15370
75%
15370
48%
23251

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
33%
2327
29%
716
73%
716
45%
1144
January16th to endNight
62%
768
37%
2496
30%
768
74%
768
47%
1185
February1st to 15thNight
63%
699
35%
2191
27%
698
75%
698
53%
1007
February16th to endNight
51%
632
40%
1876
24%
632
68%
632
52%
905
March1st to 15thNight
57%
720
37%
1980
21%
720
69%
720
52%
996
March16th to endNight
59%
759
38%
2103
20%
759
72%
759
56%
1028
April1st to 15thNight
46%
539
36%
1798
19%
539
68%
539
48%
797
April16th to endNight
50%
540
41%
1800
27%
540
73%
540
60%
707
May1st to 15thNight
52%
539
31%
1799
25%
539
66%
539
57%
752
May16th to endNight
63%
562
32%
1751
25%
561
74%
561
50%
829
June1st to 15thNight
75%
540
29%
1620
25%
540
79%
540
54%
759
June16th to endNight
77%
540
24%
1620
21%
540
80%
540
47%
829
July1st to 15thNight
81%
510
21%
1530
20%
510
81%
510
38%
872
July16th to endNight
76%
564
23%
1593
22%
531
77%
531
31%
975
August1st to 15thNight
81%
539
20%
1738
23%
536
81%
536
30%
1027
August16th to endNight
81%
573
25%
1910
29%
573
81%
573
32%
1105
September1st to 15thNight
75%
540
25%
1800
28%
540
75%
540
31%
1040
September16th to endNight
78%
612
37%
1953
33%
612
82%
612
49%
933
October1st to 15thNight
73%
684
34%
2052
27%
684
77%
684
53%
989
October16th to endNight
80%
704
41%
2112
30%
704
86%
704
65%
915
November1st to 15thNight
74%
700
42%
2100
31%
700
83%
700
66%
911
November16th to endNight
66%
781
41%
2221
28%
781
74%
781
53%
1110
December1st to 15thNight
63%
879
36%
2410
25%
879
72%
879
53%
1244
December16th to endNight
63%
768
37%
2496
30%
768
73%
768
47%
1192

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
3212323347%65%
47903
Night
321232345%7%63%
47478
TransparencyDay
18%37%15%27%27%
47599
Night
20%47%15%26%26%
47283
SeeingDay
5%7%18%27%26%14%
5119
Night
4319%40%28%3
15419

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
4313113347%64%
1611
16th to endDay
6%31321235%6%64%
1728
February1st to 15thDay
3112212345%70%
1663
16th to endDay
111231333472%
1597
March1st to 15thDay
3213323345%66%
1980
16th to endDay
2212213235%73%
2121
April1st to 15thDay
222213246%71%
2150
16th to endDay
11111112482%
2160
May1st to 15thDay
111212346%74%
2151
16th to endDay
111112226%76%
2360
June1st to 15thDay
1112212235%75%
2340
16th to endDay
211222335%8%65%
2340
July1st to 15thDay
43245%35%7%6%11%45%
2340
16th to endDay
5%315%5%47%7%7%9%41%
2467
August1st to 15thDay
5%3125%35%6%8%11%46%
2211
16th to endDay
42145%35%6%7%9%49%
2292
September1st to 15thDay
7%41342446%8%50%
2160
16th to endDay
5%211211347%66%
2004
October1st to 15thDay
4212212336%69%
1705
16th to endDay
21211223477%
1760
November1st to 15thDay
1212212237%73%
1759
16th to endDay
5%2221233468%
1722
December1st to 15thDay
5%113212346%66%
1554
16th to endDay
2413312348%63%
1728
January1st to 15thNight
431332333464%
2327
16th to endNight
6%212212445%65%
2496
February1st to 15thNight
2212213346%68%
2186
16th to endNight
2312223345%68%
1876
March1st to 15thNight
3312223346%66%
1980
16th to endNight
221211333372%
2103
April1st to 15thNight
221221445%6%66%
1798
16th to endNight
11111234476%
1800
May1st to 15thNight
222222335%72%
1799
16th to endNight
311232444468%
1751
June1st to 15thNight
2113145%5%7%66%
1620
16th to endNight
2123245%8%12%55%
1620
July1st to 15thNight
31146%35%6%8%13%44%
1620
16th to endNight
43245%46%6%8%11%41%
1701
August1st to 15thNight
33135%46%7%9%13%39%
1747
16th to endNight
32145%45%7%9%12%43%
1910
September1st to 15thNight
6%4146%36%6%6%8%46%
1800
16th to endNight
5%23223348%63%
1953
October1st to 15thNight
2312212346%68%
2052
16th to endNight
1212222477%
2112
November1st to 15thNight
2112112226%75%
2100
16th to endNight
431321233469%
2221
December1st to 15thNight
5%213312246%66%
2410
16th to endNight
3213323346%64%
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
19%36%17%35%17%
1612
16th to endDay
20%3416%37%17%
1728
February1st to 15thDay
16%16%16%27%31%
1664
16th to endDay
16%2312%36%29%
1597
March1st to 15thDay
19%25%9%31%30%
1980
16th to endDay
15%138%30%39%
2121
April1st to 15thDay
14%249%32%37%
2150
16th to endDay
8%37%26%53%
2160
May1st to 15thDay
11%25%9%26%43%
2151
16th to endDay
11%25%9%22%48%
2363
June1st to 15thDay
11%16%9%22%48%
2340
16th to endDay
16%49%11%20%36%
2340
July1st to 15thDay
28%7%13%19%17%13%
2201
16th to endDay
33%10%15%22%14%3
2312
August1st to 15thDay
28%8%16%24%18%4
2196
16th to endDay
28%8%14%19%20%9%
2292
September1st to 15thDay
29%6%11%20%20%11%
2160
16th to endDay
17%37%17%33%21%
2004
October1st to 15thDay
17%36%13%28%31%
1705
16th to endDay
13%1216%32%33%
1760
November1st to 15thDay
13%15%16%33%28%
1759
16th to endDay
18%2415%32%26%
1722
December1st to 15thDay
19%26%23%33%15%
1554
16th to endDay
20%48%25%31%10%
1728
January1st to 15thNight
23%25%14%34%19%
2327
16th to endNight
20%3416%35%19%
2496
February1st to 15thNight
17%25%16%25%31%
2196
16th to endNight
18%2410%33%29%
1876
March1st to 15thNight
17%35%12%29%30%
1980
16th to endNight
17%249%30%36%
2103
April1st to 15thNight
17%36%9%29%33%
1798
16th to endNight
10%249%25%47%
1800
May1st to 15thNight
14%25%11%22%44%
1800
16th to endNight
18%45%8%21%41%
1752
June1st to 15thNight
15%5%5%10%17%45%
1620
16th to endNight
19%6%10%13%17%31%
1620
July1st to 15thNight
25%8%13%21%17%12%
1530
16th to endNight
31%10%17%25%13%2
1593
August1st to 15thNight
31%9%17%21%15%4
1738
16th to endNight
28%11%12%22%18%7%
1910
September1st to 15thNight
32%7%13%18%16%13%
1800
16th to endNight
20%37%17%30%20%
1953
October1st to 15thNight
18%47%14%23%32%
2052
16th to endNight
12%2415%27%38%
2112
November1st to 15thNight
12%2415%34%31%
2100
16th to endNight
19%2412%31%29%
2221
December1st to 15thNight
20%26%19%31%19%
2410
16th to endNight
20%37%23%34%10%
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
18%218%43%14%2
90
16th to endDay
5%425%37%16%11%
96
February1st to 15thDay
11%311%28%28%16%
90
16th to endDay
317%23%25%22%8%
98
March1st to 15thDay
6%15%27%30%16%4
270
16th to endDay
421%31%21%16%4
288
April1st to 15thDay
5%18%33%26%13%1
269
16th to endDay
6%21%34%24%9%3
270
May1st to 15thDay
218%37%27%11%2
288
16th to endDay
27%35%34%16%2
330
June1st to 15thDay
35%20%31%26%13%
315
16th to endDay
213%27%33%22%
315
July1st to 15thDay
3426%39%25%
305
16th to endDay
7%318%36%33%
327
August1st to 15thDay
3416%39%35%
315
16th to endDay
6%219%40%30%
332
September1st to 15thDay
7%6%25%40%18%
315
16th to endDay
8%111%33%34%10%
237
October1st to 15thDay
9%18%28%30%20%
107
16th to endDay
9%15%25%36%22%
96
November1st to 15thDay
45%14%30%35%10%
90
16th to endDay
14%8%23%25%22%5%
90
December1st to 15thDay
46%17%35%25%10%
90
16th to endDay
12%8%22%46%7%2
96
January1st to 15thNight
5%122%45%21%3
720
16th to endNight
6%422%46%18%1
768
February1st to 15thNight
2425%42%22%1
704
16th to endNight
46%36%40%11%
632
March1st to 15thNight
5%7%25%42%16%1
720
16th to endNight
36%28%43%16%
759
April1st to 15thNight
49%37%37%10%
539
16th to endNight
28%36%39%10%1
540
May1st to 15thNight
25%37%45%10%
540
16th to endNight
3425%47%17%
563
June1st to 15thNight
3116%51%25%1
540
16th to endNight
113%46%36%1
540
July1st to 15thNight
46%33%52%3
510
16th to endNight
5%423%57%9%
564
August1st to 15thNight
4222%54%14%
539
16th to endNight
3421%60%10%
573
September1st to 15thNight
7%432%49%4
540
16th to endNight
7%8%44%36%3
612
October1st to 15thNight
4116%44%28%3
684
16th to endNight
2112%41%35%6%
704
November1st to 15thNight
3119%38%34%4
700
16th to endNight
6%318%37%29%3
781
December1st to 15thNight
7%420%43%23%1
879
16th to endNight
4422%50%17%1
768
Page generated at 2017-10-07 12:07:49. Version ac04

Copyright 2017 A. Danko


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