Lawrence
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lawrence clear sky chart from 2005-11-05 to 2017-09-17.

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
43%
15888
23%
47029
14%
15841
51%
15841
32%
28267

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
33%
900
22%
2327
9%
895
43%
895
33%
1460
January16th to endNight
29%
960
26%
2496
10%
960
40%
960
33%
1593
February1st to 15thNight
24%
880
16%
2288
6%
876
31%
876
24%
1614
February16th to endNight
29%
660
24%
1922
8%
660
41%
660
29%
1193
March1st to 15thNight
32%
540
22%
1980
13%
540
44%
540
25%
1158
March16th to endNight
26%
576
15%
2112
10%
576
35%
576
19%
1370
April1st to 15thNight
33%
539
21%
1868
14%
539
47%
539
28%
1078
April16th to endNight
32%
540
21%
1686
14%
540
44%
540
24%
1093
May1st to 15thNight
41%
540
20%
1620
16%
540
48%
540
28%
1039
May16th to endNight
47%
563
18%
1685
14%
561
52%
561
33%
1007
June1st to 15thNight
60%
540
20%
1464
11%
540
64%
540
41%
855
June16th to endNight
62%
540
25%
1507
16%
540
67%
540
52%
794
July1st to 15thNight
70%
510
17%
1530
14%
510
72%
510
41%
830
July16th to endNight
74%
564
25%
1594
24%
531
77%
531
44%
843
August1st to 15thNight
78%
539
24%
1610
27%
536
81%
536
42%
871
August16th to endNight
72%
573
28%
1797
31%
573
76%
573
40%
967
September1st to 15thNight
63%
540
25%
1877
27%
540
67%
540
31%
1060
September16th to endNight
60%
498
28%
1837
25%
498
68%
498
34%
965
October1st to 15thNight
46%
641
29%
1961
21%
641
52%
641
33%
1142
October16th to endNight
38%
704
28%
2112
14%
704
49%
704
37%
1171
November1st to 15thNight
43%
781
29%
2181
14%
781
54%
781
39%
1228
November16th to endNight
33%
900
25%
2463
10%
900
45%
900
35%
1485
December1st to 15thNight
30%
900
18%
2520
8%
900
39%
900
26%
1672
December16th to endNight
30%
960
21%
2592
9%
960
40%
960
25%
1779

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
9%5%2418%23346%39%
47731
Night
8%5%1318%23345%43%
47224
Cloud CoverDay
11%6%25%42445%7%45%
47729
Night
10%5%24424446%50%
47224
TransparencyDay
38%6%13%25%14%2
47429
Night
33%5%12%26%17%3
47029
SeeingDay
13%6%25%30%19%4
5907
Night
13%7%31%33%12%1
15888

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
7%5%25%21%3134440%
1611
16th to endDay
9%8%3421%1234436%
1728
February1st to 15thDay
9%7%35%20%3233435%
1575
16th to endDay
10%8%15%20%2333435%
1558
March1st to 15thDay
9%8%25%21%23445%32%
1980
16th to endDay
15%8%25%20%1323431%
2112
April1st to 15thDay
13%7%2421%2333435%
2079
16th to endDay
14%7%35%21%2333427%
2271
May1st to 15thDay
12%7%1421%23435%33%
2331
16th to endDay
11%5%25%20%3445%6%31%
2430
June1st to 15thDay
6%41420%2445%7%39%
2493
16th to endDay
221219%3445%8%45%
2446
July1st to 15thDay
6%31314%9%446%8%38%
2340
16th to endDay
5%21320%3445%8%41%
2466
August1st to 15thDay
6%21413%3445%7%45%
2340
16th to endDay
6%41412%33447%46%
2405
September1st to 15thDay
9%6%2411%22346%44%
2082
16th to endDay
6%31314%235%5%7%47%
1828
October1st to 15thDay
11%5%1412%1234446%
1658
16th to endDay
9%41312%13335%50%
1760
November1st to 15thDay
7%31217%2233450%
1674
16th to endDay
12%41320%1122444%
1495
December1st to 15thDay
14%7%25%20%1333433%
1440
16th to endDay
10%7%36%20%23335%34%
1629
January1st to 15thNight
6%5%1421%2244442%
2327
16th to endNight
7%6%25%20%1233441%
2496
February1st to 15thNight
8%9%25%21%2233434%
2278
16th to endNight
9%425%19%2333440%
1922
March1st to 15thNight
8%6%2420%1333340%
1980
16th to endNight
15%5%1320%22335%34%
2112
April1st to 15thNight
8%5%1320%2333442%
1868
16th to endNight
15%6%1320%22345%33%
1686
May1st to 15thNight
10%6%2319%22346%37%
1619
16th to endNight
9%31320%13438%39%
1683
June1st to 15thNight
42320%3335%6%45%
1464
16th to endNight
11218%12349%52%
1507
July1st to 15thNight
5%1314%8%245%7%45%
1620
16th to endNight
32320%3345%7%45%
1702
August1st to 15thNight
311213%235%6%9%51%
1620
16th to endNight
6%21212%23345%56%
1797
September1st to 15thNight
9%41312%235%46%47%
1877
16th to endNight
5%31412%24446%51%
1837
October1st to 15thNight
12%41312%2233449%
1961
16th to endNight
7%41312%2222455%
2112
November1st to 15thNight
5%41217%23235%52%
2181
16th to endNight
10%41219%1223447%
2463
December1st to 15thNight
11%7%2420%2334435%
2520
16th to endNight
11%8%2419%2223436%
2592

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
11%5%36%433345%48%
1611
16th to endDay
11%9%46%31335%6%44%
1728
February1st to 15thDay
11%8%5%6%433345%41%
1575
16th to endDay
10%9%25%5%24445%43%
1558
March1st to 15thDay
11%9%36%5%245%5%6%38%
1980
16th to endDay
20%9%35%424345%35%
2110
April1st to 15thDay
16%8%245%24445%42%
2079
16th to endDay
18%8%36%5%24435%35%
2271
May1st to 15thDay
16%8%35%5%34446%37%
2331
16th to endDay
14%6%35%43446%7%38%
2430
June1st to 15thDay
7%424426%5%7%8%45%
2493
16th to endDay
5%213335%5%6%10%52%
2446
July1st to 15thDay
8%3145%35%5%7%9%46%
2340
16th to endDay
6%3144345%6%9%49%
2466
August1st to 15thDay
6%3145%345%7%8%48%
2340
16th to endDay
8%4245%2445%8%49%
2405
September1st to 15thDay
11%6%25%323347%48%
2082
16th to endDay
7%3244245%6%6%51%
1828
October1st to 15thDay
13%6%1342235%6%51%
1658
16th to endDay
12%413423346%53%
1760
November1st to 15thDay
9%423324346%56%
1674
16th to endDay
15%424313336%51%
1495
December1st to 15thDay
15%9%34433345%41%
1440
16th to endDay
13%8%47%424347%38%
1629
January1st to 15thNight
8%5%245%23446%51%
2327
16th to endNight
9%7%26%413345%50%
2496
February1st to 15thNight
10%10%47%5%3335%5%39%
2278
16th to endNight
10%6%25%434446%48%
1922
March1st to 15thNight
10%7%25%425%35%5%48%
1980
16th to endNight
19%6%34324347%39%
2112
April1st to 15thNight
11%6%24324336%51%
1868
16th to endNight
18%6%24424346%42%
1686
May1st to 15thNight
12%7%2442346%7%43%
1619
16th to endNight
10%42342345%9%48%
1683
June1st to 15thNight
6%213345%5%5%9%53%
1464
16th to endNight
41231346%10%61%
1507
July1st to 15thNight
5%21341447%9%54%
1620
16th to endNight
5%2134345%5%9%53%
1702
August1st to 15thNight
32133245%8%10%54%
1620
16th to endNight
8%313423345%59%
1797
September1st to 15thNight
10%4234245%46%50%
1877
16th to endNight
6%314425%45%6%56%
1837
October1st to 15thNight
14%414323345%53%
1961
16th to endNight
10%5%13322335%59%
2112
November1st to 15thNight
7%424223336%59%
2181
16th to endNight
14%5%23213245%53%
2463
December1st to 15thNight
13%8%3442435%5%43%
2520
16th to endNight
15%9%35%423346%41%
2592

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%413%25%16%1
1612
16th to endDay
41%415%25%11%1
1728
February1st to 15thDay
45%5%15%23%9%1
1576
16th to endDay
42%413%25%12%2
1558
March1st to 15thDay
43%6%13%23%11%2
1980
16th to endDay
51%5%12%20%9%1
2112
April1st to 15thDay
43%5%11%22%16%
2079
16th to endDay
50%5%12%20%11%
2271
May1st to 15thDay
47%7%10%22%12%
2331
16th to endDay
43%8%15%20%11%1
2434
June1st to 15thDay
33%9%15%26%14%1
2493
16th to endDay
25%7%17%29%17%1
2446
July1st to 15thDay
32%8%17%26%13%2
2201
16th to endDay
27%7%15%31%15%2
2311
August1st to 15thDay
30%8%14%27%16%2
2326
16th to endDay
32%6%11%25%16%6%
2405
September1st to 15thDay
35%5%11%24%17%5%
2082
16th to endDay
30%7%12%27%21%1
1828
October1st to 15thDay
34%410%26%20%3
1658
16th to endDay
32%412%26%20%4
1760
November1st to 15thDay
28%5%11%27%21%5%
1674
16th to endDay
37%39%30%18%
1495
December1st to 15thDay
44%5%15%25%9%
1440
16th to endDay
46%412%21%12%2
1629
January1st to 15thNight
33%5%15%25%18%1
2327
16th to endNight
36%412%27%16%2
2496
February1st to 15thNight
46%5%12%22%11%1
2288
16th to endNight
37%412%23%19%3
1922
March1st to 15thNight
37%5%11%24%16%4
1980
16th to endNight
45%5%13%21%11%2
2112
April1st to 15thNight
35%410%27%19%2
1868
16th to endNight
42%411%24%16%1
1686
May1st to 15thNight
38%6%12%23%16%1
1620
16th to endNight
32%7%18%25%14%1
1685
June1st to 15thNight
25%7%16%32%14%3
1464
16th to endNight
17%7%14%34%22%3
1507
July1st to 15thNight
24%7%15%32%16%3
1530
16th to endNight
24%5%13%32%21%2
1594
August1st to 15thNight
21%9%15%32%17%3
1610
16th to endNight
26%5%9%27%24%7%
1797
September1st to 15thNight
32%6%10%24%19%7%
1877
16th to endNight
27%6%11%26%24%3
1837
October1st to 15thNight
33%47%24%23%6%
1961
16th to endNight
29%39%30%22%4
2112
November1st to 15thNight
27%411%25%23%7%
2181
16th to endNight
33%39%31%18%2
2463
December1st to 15thNight
42%414%25%11%
2520
16th to endNight
44%5%12%21%12%3
2592

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
22%16%42%13%5%
90
16th to endDay
17%9%44%22%41
96
February1st to 15thDay
8%23%43%21%3
90
16th to endDay
13%19%37%19%9%
81
March1st to 15thDay
15%21%45%14%3
90
16th to endDay
28%14%35%16%5%
96
April1st to 15thDay
20%9%33%27%8%
198
16th to endDay
23%11%35%20%8%1
381
May1st to 15thDay
19%10%31%25%11%1
468
16th to endDay
18%7%32%26%12%2
517
June1st to 15thDay
9%325%37%19%5%
495
16th to endDay
6%429%36%19%4
495
July1st to 15thDay
10%117%37%28%5%
475
16th to endDay
7%111%35%38%6%
515
August1st to 15thDay
6%110%38%35%6%
493
16th to endDay
10%214%33%31%6%
445
September1st to 15thDay
8%217%37%26%8%
237
16th to endDay
8%223%40%13%10%
93
October1st to 15thDay
8%6%25%34%14%10%
90
16th to endDay
8%5%42%31%11%1
96
November1st to 15thDay
6%425%36%15%11%
90
16th to endDay
32%16%32%14%31
90
December1st to 15thDay
18%12%45%14%5%3
90
16th to endDay
20%20%34%20%3
96
January1st to 15thNight
12%13%37%29%6%
900
16th to endNight
13%11%41%29%4
960
February1st to 15thNight
16%11%40%28%3
880
16th to endNight
14%10%42%27%5%
660
March1st to 15thNight
14%10%38%29%6%
540
16th to endNight
22%9%38%23%5%
576
April1st to 15thNight
14%11%36%31%5%
539
16th to endNight
19%9%34%27%8%
540
May1st to 15thNight
16%5%32%32%12%
540
16th to endNight
11%434%33%14%1
563
June1st to 15thNight
7%225%46%18%1
540
16th to endNight
5%227%46%17%
540
July1st to 15thNight
7%115%47%25%2
510
16th to endNight
6%12%48%30%1
564
August1st to 15thNight
49%47%36%1
539
16th to endNight
9%112%39%34%4
573
September1st to 15thNight
11%217%40%24%3
540
16th to endNight
7%322%39%23%3
498
October1st to 15thNight
17%427%30%18%1
641
16th to endNight
14%8%36%28%12%
704
November1st to 15thNight
9%11%33%31%13%
781
16th to endNight
17%11%36%28%6%
900
December1st to 15thNight
18%12%36%28%4
900
16th to endNight
19%9%34%30%5%
960
Page generated at 2017-09-18 07:38:21. Version ac04

Copyright 2017 A. Danko


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