Lake Sylvia Recreation Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Sylvia Recreation Area clear sky chart from 2005-11-05 to 2017-09-20.

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
44%
15666
25%
47247
16%
15621
54%
15621
31%
27686

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%
899
29%
2327
9%
895
40%
895
28%
1448
January16th to endNight
23%
960
28%
2496
8%
960
36%
960
29%
1564
February1st to 15thNight
21%
874
20%
2283
5%
871
31%
871
26%
1495
February16th to endNight
23%
592
28%
1854
9%
592
39%
592
26%
1069
March1st to 15thNight
27%
540
22%
1980
13%
540
40%
540
21%
1208
March16th to endNight
31%
576
20%
2112
14%
576
41%
576
23%
1295
April1st to 15thNight
30%
539
25%
1809
12%
539
48%
539
29%
987
April16th to endNight
34%
540
24%
1800
15%
540
50%
540
29%
1030
May1st to 15thNight
44%
540
19%
1734
13%
540
54%
540
26%
1066
May16th to endNight
50%
563
22%
1685
16%
561
58%
561
31%
1023
June1st to 15thNight
75%
540
22%
1620
20%
540
79%
540
46%
848
June16th to endNight
72%
540
25%
1620
24%
540
76%
540
43%
862
July1st to 15thNight
70%
510
18%
1530
18%
510
73%
510
35%
890
July16th to endNight
82%
564
25%
1594
27%
531
84%
531
42%
864
August1st to 15thNight
76%
539
24%
1643
28%
536
78%
536
40%
891
August16th to endNight
75%
573
24%
1910
29%
573
76%
573
33%
1078
September1st to 15thNight
68%
540
26%
1800
28%
540
71%
540
34%
1016
September16th to endNight
65%
551
32%
1869
30%
551
70%
551
37%
977
October1st to 15thNight
56%
660
31%
1980
23%
660
61%
660
38%
1103
October16th to endNight
48%
704
35%
2112
21%
704
60%
704
39%
1130
November1st to 15thNight
46%
700
31%
2100
20%
700
56%
700
35%
1159
November16th to endNight
33%
762
29%
2325
16%
762
47%
762
28%
1373
December1st to 15thNight
31%
900
21%
2520
10%
900
41%
900
27%
1627
December16th to endNight
28%
960
24%
2544
9%
960
39%
960
25%
1683

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
12%5%25%5%35%45%6%43%
47577
Night
11%42442335%7%51%
47442
TransparencyDay
39%5%10%21%17%4
47277
Night
33%410%23%21%6%
47247
SeeingDay
13%6%22%27%22%7%
5717
Night
14%10%26%29%18%2
15667

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
17%5%23323345%48%
1611
16th to endDay
13%5%36%42323449%
1728
February1st to 15thDay
17%6%2342334347%
1579
16th to endDay
15%7%36%5%2444441%
1630
March1st to 15thDay
19%6%24424335%43%
1980
16th to endDay
16%6%36%5%24445%40%
2110
April1st to 15thDay
12%5%25%42345%6%47%
2136
16th to endDay
15%5%25%5%25%445%42%
2160
May1st to 15thDay
16%6%35%5%35%346%38%
2214
16th to endDay
11%436%6%47%6%6%7%35%
2430
June1st to 15thDay
6%5%25%5%46%6%7%8%41%
2340
16th to endDay
5%4246%47%6%7%10%41%
2340
July1st to 15thDay
7%5%36%8%47%7%6%9%34%
2340
16th to endDay
6%3246%38%6%7%9%40%
2466
August1st to 15thDay
8%4246%46%6%7%8%38%
2305
16th to endDay
9%425%5%47%6%7%8%38%
2292
September1st to 15thDay
15%414435%45%7%43%
2160
16th to endDay
13%314424445%51%
1846
October1st to 15thDay
13%5%14423335%51%
1650
16th to endDay
14%312312335%58%
1760
November1st to 15thDay
10%5%23313246%57%
1758
16th to endDay
15%6%25%322335%50%
1628
December1st to 15thDay
15%7%24323345%46%
1440
16th to endDay
15%7%36%5%2433443%
1674
January1st to 15thNight
15%5%14322335%52%
2327
16th to endNight
15%5%2332333452%
2496
February1st to 15thNight
16%5%35%323345%46%
2273
16th to endNight
13%5%23313346%51%
1854
March1st to 15thNight
18%5%245%23245%44%
1980
16th to endNight
15%6%24424346%44%
2112
April1st to 15thNight
10%22442335%6%52%
1809
16th to endNight
10%425%324346%50%
1800
May1st to 15thNight
12%4235%25%447%46%
1733
16th to endNight
8%5%245%25%35%9%45%
1683
June1st to 15thNight
421222447%9%59%
1620
16th to endNight
421322345%10%57%
1620
July1st to 15thNight
3325%5%35%6%8%11%43%
1620
16th to endNight
3113325%5%7%11%53%
1702
August1st to 15thNight
5%2134245%6%11%51%
1653
16th to endNight
6%3244345%7%10%46%
1910
September1st to 15thNight
10%424324345%54%
1800
16th to endNight
7%31332446%7%55%
1869
October1st to 15thNight
10%414313346%55%
1980
16th to endNight
12%31331222363%
2112
November1st to 15thNight
9%323423346%56%
2100
16th to endNight
15%5%2342424451%
2325
December1st to 15thNight
16%5%34423345%46%
2520
16th to endNight
16%6%35%423335%45%
2544

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
39%36%23%19%5%
1612
16th to endDay
40%26%24%21%4
1728
February1st to 15thDay
40%310%23%17%4
1580
16th to endDay
45%36%19%17%5%
1630
March1st to 15thDay
44%48%17%17%6%
1980
16th to endDay
45%5%10%22%14%1
2112
April1st to 15thDay
38%5%10%21%18%5%
2136
16th to endDay
43%49%19%19%3
2160
May1st to 15thDay
46%5%8%17%18%3
2214
16th to endDay
44%7%12%21%12%1
2434
June1st to 15thDay
36%7%12%24%17%1
2340
16th to endDay
34%7%13%23%17%2
2340
July1st to 15thDay
40%9%14%23%10%1
2201
16th to endDay
34%8%16%25%13%1
2311
August1st to 15thDay
37%8%14%22%14%2
2291
16th to endDay
39%8%14%20%13%3
2292
September1st to 15thDay
38%6%10%18%16%7%
2160
16th to endDay
32%410%21%24%6%
1846
October1st to 15thDay
35%48%20%23%8%
1650
16th to endDay
28%25%24%27%10%
1760
November1st to 15thDay
29%37%27%23%8%
1758
16th to endDay
38%27%19%25%6%
1628
December1st to 15thDay
41%311%21%16%5%
1440
16th to endDay
44%39%19%17%4
1674
January1st to 15thNight
37%26%22%27%4
2327
16th to endNight
36%36%24%22%6%
2496
February1st to 15thNight
40%38%22%18%6%
2283
16th to endNight
34%39%25%19%7%
1854
March1st to 15thNight
43%39%17%18%7%
1980
16th to endNight
41%49%23%18%2
2112
April1st to 15thNight
30%411%23%20%8%
1809
16th to endNight
34%410%24%22%4
1800
May1st to 15thNight
37%6%10%20%18%6%
1734
16th to endNight
34%6%16%24%16%1
1685
June1st to 15thNight
19%8%14%32%23%1
1620
16th to endNight
23%6%13%28%23%5%
1620
July1st to 15thNight
28%9%17%27%14%2
1530
16th to endNight
21%9%16%31%18%2
1594
August1st to 15thNight
24%7%16%30%18%2
1643
16th to endNight
29%8%16%24%17%3
1910
September1st to 15thNight
30%6%10%23%21%7%
1800
16th to endNight
27%5%9%23%25%9%
1869
October1st to 15thNight
29%410%20%24%11%
1980
16th to endNight
27%2421%31%12%
2112
November1st to 15thNight
29%37%24%23%11%
2100
16th to endNight
36%26%19%28%5%
2325
December1st to 15thNight
41%39%20%18%6%
2520
16th to endNight
42%38%21%19%5%
2544

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
20%16%42%16%4
90
16th to endDay
26%23%34%9%6%
96
February1st to 15thDay
23%15%46%10%31
90
16th to endDay
19%35%27%12%31
81
March1st to 15thDay
30%15%45%7%1
90
16th to endDay
21%19%28%27%3
96
April1st to 15thDay
20%15%35%17%9%1
255
16th to endDay
21%13%31%18%14%1
270
May1st to 15thDay
18%11%35%19%11%2
351
16th to endDay
14%7%32%27%13%4
517
June1st to 15thDay
9%316%36%27%7%
495
16th to endDay
6%220%37%26%6%
495
July1st to 15thDay
7%217%37%27%6%
475
16th to endDay
6%6%31%37%17%
515
August1st to 15thDay
10%11%31%33%12%
458
16th to endDay
15%15%26%37%13%
332
September1st to 15thDay
12%111%20%41%12%
315
16th to endDay
11%213%34%24%13%
144
October1st to 15thDay
7%333%36%14%4
90
16th to endDay
19%323%35%14%3
96
November1st to 15thDay
16%6%32%17%23%3
90
16th to endDay
36%15%24%16%5%1
90
December1st to 15thDay
21%18%32%14%11%2
90
16th to endDay
21%21%41%11%3
96
January1st to 15thNight
21%19%30%24%5%
900
16th to endNight
18%17%38%21%3
960
February1st to 15thNight
20%18%36%21%3
874
16th to endNight
20%19%34%22%2
592
March1st to 15thNight
20%12%35%26%4
540
16th to endNight
16%11%35%28%7%
576
April1st to 15thNight
13%16%37%23%9%
539
16th to endNight
12%12%36%26%10%
540
May1st to 15thNight
13%7%30%35%11%1
540
16th to endNight
12%5%24%32%21%3
563
June1st to 15thNight
5%113%42%32%5%
540
16th to endNight
5%113%37%37%3
540
July1st to 15thNight
312%38%38%5%
510
16th to endNight
36%33%45%10%
564
August1st to 15thNight
47%36%41%8%
539
16th to endNight
8%7%33%42%6%
573
September1st to 15thNight
12%111%27%42%5%
540
16th to endNight
9%115%31%36%4
551
October1st to 15thNight
12%421%30%27%3
660
16th to endNight
14%8%25%31%18%1
704
November1st to 15thNight
11%11%27%32%15%1
700
16th to endNight
16%16%30%23%12%
762
December1st to 15thNight
19%12%32%27%7%
900
16th to endNight
21%14%31%26%5%
960
Page generated at 2017-09-21 06:18:16. Version ac04

Copyright 2017 A. Danko


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