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.

Jordan Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jordan Lake clear sky chart from 2005-11-05 to 2017-09-10.

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
46%
15919
21%
46977
14%
15883
54%
15883
27%
29805

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
30%
716
23%
2327
12%
716
44%
716
23%
1431
January16th to endNight
28%
768
24%
2496
12%
768
44%
768
26%
1516
February1st to 15thNight
27%
701
21%
2287
10%
701
43%
701
25%
1370
February16th to endNight
27%
631
28%
1847
12%
631
45%
631
29%
1104
March1st to 15thNight
32%
720
25%
1980
13%
720
44%
720
29%
1238
March16th to endNight
33%
768
21%
2112
11%
768
42%
768
26%
1390
April1st to 15thNight
35%
718
23%
1847
9%
718
43%
718
32%
1187
April16th to endNight
40%
720
21%
1800
8%
720
46%
720
32%
1184
May1st to 15thNight
44%
559
17%
1639
8%
559
50%
559
27%
1077
May16th to endNight
60%
561
16%
1683
12%
561
62%
561
29%
1074
June1st to 15thNight
59%
540
14%
1620
13%
540
61%
540
25%
1070
June16th to endNight
67%
540
17%
1620
13%
540
69%
540
28%
1048
July1st to 15thNight
69%
510
12%
1530
10%
510
70%
510
26%
1029
July16th to endNight
72%
564
15%
1595
12%
531
74%
531
27%
1037
August1st to 15thNight
67%
539
14%
1609
12%
536
68%
536
24%
1112
August16th to endNight
65%
735
16%
1881
11%
735
66%
735
27%
1308
September1st to 15thNight
65%
700
25%
1777
19%
700
66%
700
34%
1158
September16th to endNight
47%
657
15%
1834
12%
657
51%
657
21%
1319
October1st to 15thNight
48%
660
27%
1980
25%
660
56%
660
29%
1245
October16th to endNight
46%
704
33%
2112
22%
704
62%
704
36%
1184
November1st to 15thNight
48%
700
28%
2101
20%
700
60%
700
34%
1212
November16th to endNight
44%
720
25%
2317
18%
720
54%
720
29%
1367
December1st to 15thNight
38%
720
21%
2487
15%
720
49%
720
22%
1539
December16th to endNight
32%
768
24%
2496
15%
768
44%
768
22%
1606

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%2443445%7%43%
47625
Night
13%5%2442445%7%45%
47171
Cloud CoverDay
13%5%2443445%7%43%
47635
Night
13%42442445%7%45%
47175
TransparencyDay
39%7%11%20%17%4
47336
Night
37%6%11%19%19%5%
46978
SeeingDay
16%6%21%25%21%9%
5716
Night
15%6%25%31%18%1
15928

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
19%5%24423345%43%
1611
16th to endDay
17%6%23223335%48%
1728
February1st to 15thDay
16%6%24423445%45%
1575
16th to endDay
16%5%24312345%48%
1622
March1st to 15thDay
13%413333446%50%
1969
16th to endDay
16%6%245%23345%44%
2112
April1st to 15thDay
10%413223448%52%
2101
16th to endDay
13%4245%25%5%5%6%43%
2160
May1st to 15thDay
13%6%25%5%35%5%5%7%38%
2322
16th to endDay
9%5%145%36%6%6%8%42%
2431
June1st to 15thDay
9%425%5%36%5%7%9%39%
2340
16th to endDay
7%425%5%35%6%7%10%41%
2340
July1st to 15thDay
8%5%26%6%47%7%8%11%32%
2340
16th to endDay
6%426%8%5%7%8%6%10%32%
2465
August1st to 15thDay
10%5%26%6%46%7%7%10%31%
2340
16th to endDay
11%6%36%6%5%6%7%8%9%30%
2309
September1st to 15thDay
10%314445%46%8%46%
2069
16th to endDay
23%6%26%424345%36%
1796
October1st to 15thDay
17%5%13323246%49%
1650
16th to endDay
11%41431234357%
1760
November1st to 15thDay
15%323213345%55%
1757
16th to endDay
14%424423346%49%
1633
December1st to 15thDay
16%6%24322446%45%
1467
16th to endDay
19%7%2432443443%
1728
January1st to 15thNight
15%6%24424336%46%
2327
16th to endNight
17%5%24423435%46%
2496
February1st to 15thNight
17%423323346%48%
2285
16th to endNight
13%41332446%5%49%
1847
March1st to 15thNight
13%42442335%6%49%
1968
16th to endNight
16%424433446%44%
2112
April1st to 15thNight
13%5%24424346%48%
1847
16th to endNight
13%42442445%8%45%
1800
May1st to 15thNight
12%5%35%6%35%46%8%40%
1639
16th to endNight
11%5%145%346%5%9%43%
1682
June1st to 15thNight
10%436%5%35%6%6%9%38%
1620
16th to endNight
6%425%5%35%6%7%10%42%
1620
July1st to 15thNight
7%415%6%36%6%8%11%37%
1620
16th to endNight
6%4245%46%6%8%13%36%
1703
August1st to 15thNight
11%4246%36%6%7%10%35%
1620
16th to endNight
7%5%35%6%35%6%7%11%35%
1881
September1st to 15thNight
11%5%2342345%7%48%
1777
16th to endNight
19%7%25%6%34445%36%
1834
October1st to 15thNight
18%5%2441223448%
1980
16th to endNight
12%314312235%57%
2112
November1st to 15thNight
13%324323245%54%
2101
16th to endNight
14%32432345%6%49%
2317
December1st to 15thNight
16%5%24424446%45%
2487
16th to endNight
20%7%24423346%41%
2496

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
19%5%34423345%44%
1611
16th to endDay
17%5%23223335%48%
1728
February1st to 15thDay
16%5%24423435%46%
1575
16th to endDay
16%5%24323345%48%
1622
March1st to 15thDay
14%413233446%50%
1980
16th to endDay
17%6%24433345%44%
2111
April1st to 15thDay
11%413323348%53%
2101
16th to endDay
13%425%425%46%7%43%
2160
May1st to 15thDay
13%6%25%6%36%5%5%7%38%
2322
16th to endDay
9%4245%35%5%7%8%42%
2431
June1st to 15thDay
9%5%25%5%45%5%7%9%39%
2340
16th to endDay
7%4245%35%6%7%10%41%
2340
July1st to 15thDay
8%5%26%6%47%7%8%10%32%
2340
16th to endDay
6%5%26%8%5%7%7%7%10%33%
2465
August1st to 15thDay
10%5%26%7%46%6%7%10%31%
2340
16th to endDay
11%6%26%6%46%6%8%9%30%
2309
September1st to 15thDay
10%31443446%8%46%
2069
16th to endDay
23%6%26%423345%37%
1796
October1st to 15thDay
17%5%13323246%49%
1650
16th to endDay
12%42431233457%
1760
November1st to 15thDay
15%313213235%55%
1757
16th to endDay
14%423424346%49%
1633
December1st to 15thDay
16%6%24323347%44%
1467
16th to endDay
20%7%2342443443%
1728
January1st to 15thNight
16%5%24424436%46%
2327
16th to endNight
16%5%24423445%46%
2496
February1st to 15thNight
17%423323346%48%
2278
16th to endNight
13%31232446%6%49%
1847
March1st to 15thNight
14%32432335%6%49%
1980
16th to endNight
15%425%423446%45%
2112
April1st to 15thNight
13%424424337%48%
1847
16th to endNight
13%42443445%8%45%
1800
May1st to 15thNight
12%5%35%6%3445%8%40%
1638
16th to endNight
11%5%145%345%6%9%42%
1682
June1st to 15thNight
10%5%26%5%35%6%6%9%38%
1620
16th to endNight
6%425%5%35%6%7%10%42%
1620
July1st to 15thNight
8%325%6%36%6%8%11%37%
1620
16th to endNight
6%4345%46%6%8%13%37%
1703
August1st to 15thNight
11%5%245%36%6%7%10%35%
1620
16th to endNight
8%5%36%6%35%6%7%11%35%
1881
September1st to 15thNight
11%5%2342345%7%48%
1777
16th to endNight
19%6%36%6%34435%36%
1834
October1st to 15thNight
18%5%33412335%49%
1980
16th to endNight
12%314322335%57%
2112
November1st to 15thNight
13%414323245%54%
2101
16th to endNight
14%32432335%6%49%
2317
December1st to 15thNight
16%5%24324436%45%
2487
16th to endNight
20%6%24423345%41%
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
44%45%19%21%4
1612
16th to endDay
38%38%21%20%7%
1728
February1st to 15thDay
40%37%20%22%5%
1577
16th to endDay
38%49%22%20%4
1622
March1st to 15thDay
35%5%10%21%21%5%
1980
16th to endDay
42%5%9%20%17%4
2112
April1st to 15thDay
29%5%10%27%19%7%
2101
16th to endDay
39%7%10%17%18%7%
2160
May1st to 15thDay
43%8%13%19%13%2
2322
16th to endDay
37%8%16%22%13%1
2435
June1st to 15thDay
37%9%17%20%13%
2340
16th to endDay
35%11%14%20%15%2
2340
July1st to 15thDay
41%12%15%17%9%2
2201
16th to endDay
42%11%18%18%8%1
2310
August1st to 15thDay
44%10%16%17%9%1
2327
16th to endDay
44%11%14%19%9%1
2309
September1st to 15thDay
34%8%14%19%17%5%
2069
16th to endDay
49%6%8%15%16%3
1796
October1st to 15thDay
37%310%24%18%5%
1650
16th to endDay
31%37%22%27%7%
1760
November1st to 15thDay
31%39%17%28%8%
1757
16th to endDay
35%48%20%24%5%
1633
December1st to 15thDay
39%410%21%17%5%
1467
16th to endDay
44%39%18%18%4
1728
January1st to 15thNight
39%49%15%24%6%
2327
16th to endNight
39%37%21%21%6%
2496
February1st to 15thNight
38%38%19%24%6%
2287
16th to endNight
33%5%10%22%22%5%
1847
March1st to 15thNight
35%5%9%21%20%7%
1980
16th to endNight
39%6%8%20%20%4
2112
April1st to 15thNight
37%38%20%23%6%
1847
16th to endNight
36%7%10%20%16%9%
1800
May1st to 15thNight
40%6%13%20%16%2
1639
16th to endNight
35%8%16%22%14%1
1684
June1st to 15thNight
40%8%16%18%13%2
1620
16th to endNight
34%12%15%20%14%3
1620
July1st to 15thNight
35%14%16%20%11%2
1530
16th to endNight
34%12%19%20%10%2
1595
August1st to 15thNight
40%11%17%17%11%1
1609
16th to endNight
37%12%18%20%8%1
1881
September1st to 15thNight
34%8%13%20%17%5%
1777
16th to endNight
48%7%11%11%17%3
1834
October1st to 15thNight
40%38%18%23%5%
1980
16th to endNight
30%37%21%25%10%
2112
November1st to 15thNight
32%48%15%27%11%
2101
16th to endNight
35%47%18%23%9%
2317
December1st to 15thNight
40%5%8%20%19%5%
2487
16th to endNight
44%38%18%18%5%
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
25%12%41%18%2
90
16th to endDay
19%25%38%14%2
96
February1st to 15thDay
22%17%50%8%1
90
16th to endDay
17%14%40%20%6%
182
March1st to 15thDay
15%14%38%22%7%
270
16th to endDay
18%13%31%25%9%1
288
April1st to 15thDay
17%12%28%24%13%4
270
16th to endDay
18%422%32%15%5%
270
May1st to 15thDay
16%13%27%23%12%6%
288
16th to endDay
15%316%24%29%10%
331
June1st to 15thDay
13%314%28%29%10%
315
16th to endDay
10%119%28%29%10%
315
July1st to 15thDay
10%10%31%34%12%
305
16th to endDay
7%28%23%38%18%
326
August1st to 15thDay
15%13%22%29%18%
313
16th to endDay
13%19%25%28%22%
332
September1st to 15thDay
11%212%24%28%20%
294
16th to endDay
33%312%21%22%6%
254
October1st to 15thDay
23%419%25%18%8%
255
16th to endDay
12%5%22%31%22%6%
272
November1st to 15thDay
19%8%24%24%20%3
265
16th to endDay
13%11%19%34%17%3
134
December1st to 15thDay
21%13%38%13%12%
65
16th to endDay
32%12%32%16%6%
96
January1st to 15thNight
18%13%32%27%8%
720
16th to endNight
19%10%38%28%2
768
February1st to 15thNight
19%13%36%29%1
704
16th to endNight
14%14%40%25%4
631
March1st to 15thNight
15%12%36%28%6%
720
16th to endNight
17%9%34%28%8%
768
April1st to 15thNight
17%11%33%27%10%
718
16th to endNight
14%7%34%30%12%1
720
May1st to 15thNight
14%5%30%36%12%
559
16th to endNight
14%115%38%27%1
563
June1st to 15thNight
12%115%38%28%3
540
16th to endNight
8%15%38%33%3
540
July1st to 15thNight
8%11%37%38%2
510
16th to endNight
7%9%34%40%6%
564
August1st to 15thNight
13%7%35%37%5%
539
16th to endNight
10%19%33%39%6%
735
September1st to 15thNight
12%111%31%38%4
700
16th to endNight
22%215%31%27%
657
October1st to 15thNight
21%321%28%21%3
660
16th to endNight
13%6%28%26%22%1
704
November1st to 15thNight
15%5%27%33%15%2
700
16th to endNight
15%9%26%31%15%
720
December1st to 15thNight
19%8%28%34%9%
720
16th to endNight
22%10%28%31%7%
768
Page generated at 2017-09-11 19:35:34. Version ac04

Copyright 2017 A. Danko


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