Dr. T. K. Lawless Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dr. T. K. Lawless Park clear sky chart from 2005-11-05 to 2017-09-22.

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
37%
15949
15%
46869
10%
15907
42%
15907
21%
32952

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
16%
900
8%
2506
3%
895
20%
895
11%
2047
January16th to endNight
18%
959
7%
2687
3%
959
22%
959
11%
2222
February1st to 15thNight
19%
701
9%
2163
3%
701
24%
701
12%
1686
February16th to endNight
26%
631
12%
1893
6%
631
31%
631
13%
1456
March1st to 15thNight
29%
720
13%
2142
8%
720
33%
720
18%
1539
March16th to endNight
33%
720
16%
2064
9%
720
39%
720
20%
1456
April1st to 15thNight
30%
539
14%
1797
9%
539
38%
539
19%
1234
April16th to endNight
35%
540
19%
1662
11%
540
44%
540
23%
1108
May1st to 15thNight
37%
540
14%
1620
7%
540
43%
540
22%
1133
May16th to endNight
50%
562
16%
1579
10%
561
54%
561
31%
1002
June1st to 15thNight
54%
540
17%
1440
12%
540
58%
540
37%
896
June16th to endNight
59%
540
14%
1440
10%
540
63%
540
34%
908
July1st to 15thNight
65%
510
17%
1360
14%
510
66%
510
41%
814
July16th to endNight
70%
564
21%
1420
17%
531
72%
531
40%
839
August1st to 15thNight
73%
539
22%
1609
19%
536
75%
536
38%
908
August16th to endNight
65%
573
21%
1856
20%
573
69%
573
31%
1090
September1st to 15thNight
64%
606
26%
1866
24%
606
67%
606
35%
1077
September16th to endNight
58%
685
26%
1892
20%
685
61%
685
34%
1159
October1st to 15thNight
50%
660
25%
1831
18%
660
55%
660
30%
1176
October16th to endNight
26%
704
15%
2282
9%
704
35%
704
18%
1581
November1st to 15thNight
33%
700
20%
2276
16%
700
41%
700
22%
1488
November16th to endNight
25%
720
12%
2340
9%
720
29%
720
12%
1795
December1st to 15thNight
16%
836
7%
2456
3%
836
20%
836
10%
2030
December16th to endNight
15%
960
6%
2688
2%
960
18%
960
8%
2308

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
14%9%46%5%3445%7%33%
48021
Night
15%9%47%5%34446%34%
47039
Cloud CoverDay
14%9%46%5%3445%7%33%
48030
Night
15%9%47%5%34446%34%
47044
TransparencyDay
49%411%19%11%1
47709
Night
50%411%20%11%1
46869
SeeingDay
16%6%25%25%17%7%
5949
Night
20%7%27%30%13%1
15953

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
18%18%5%11%8%3444415%
1432
16th to endDay
13%18%12%11%10%5%5%32412%
1536
February1st to 15thDay
13%15%8%12%8%5%5%5%4416%
1696
16th to endDay
16%12%8%12%7%4445%5%17%
1580
March1st to 15thDay
17%12%5%8%6%25%45%7%24%
1808
16th to endDay
19%8%46%5%34347%30%
2169
April1st to 15thDay
20%12%45%423346%33%
2151
16th to endDay
18%8%25%42435%7%37%
2298
May1st to 15thDay
21%7%36%43445%7%31%
2331
16th to endDay
11%6%36%5%45%5%47%40%
2533
June1st to 15thDay
10%5%25%6%345%5%7%43%
2520
16th to endDay
9%4245%46%6%7%8%39%
2520
July1st to 15thDay
7%5%25%5%345%5%9%44%
2520
16th to endDay
6%425%435%6%7%10%42%
2652
August1st to 15thDay
6%4146%36%5%7%9%42%
2340
16th to endDay
11%5%25%5%345%48%42%
2345
September1st to 15thDay
12%4244245%5%7%45%
2082
16th to endDay
12%5%25%5%2447%8%40%
1881
October1st to 15thDay
14%7%26%5%35%447%39%
1799
16th to endDay
22%8%35%5%3435%7%29%
1587
November1st to 15thDay
14%10%345%3345%7%37%
1582
16th to endDay
20%17%6%8%5%25%345%21%
1620
December1st to 15thDay
16%19%10%9%6%2342419%
1503
16th to endDay
22%16%8%11%6%3444413%
1536
January1st to 15thNight
20%14%6%9%7%34445%18%
2506
16th to endNight
14%14%8%11%9%45%446%16%
2687
February1st to 15thNight
16%12%7%10%7%34446%22%
2161
16th to endNight
16%11%6%9%6%35%45%5%23%
1893
March1st to 15thNight
17%10%47%5%33446%33%
2129
16th to endNight
16%6%47%5%25%436%34%
2064
April1st to 15thNight
18%8%35%5%35%446%33%
1797
16th to endNight
18%6%2443445%5%39%
1662
May1st to 15thNight
19%7%26%4345%5%7%33%
1620
16th to endNight
13%6%14425%45%8%43%
1577
June1st to 15thNight
10%4345%2445%8%47%
1440
16th to endNight
8%5%244245%8%10%42%
1440
July1st to 15thNight
6%216%4245%6%8%51%
1440
16th to endNight
7%31343445%10%51%
1516
August1st to 15thNight
6%214425%5%6%8%51%
1620
16th to endNight
9%415%43335%8%48%
1856
September1st to 15thNight
11%41442345%6%51%
1866
16th to endNight
12%5%23433446%48%
1892
October1st to 15thNight
15%5%23424447%45%
1831
16th to endNight
22%10%36%423245%34%
2282
November1st to 15thNight
14%9%36%5%2345%5%38%
2276
16th to endNight
20%14%5%8%6%33346%23%
2340
December1st to 15thNight
20%16%9%9%6%2434418%
2456
16th to endNight
23%16%6%10%7%4443413%
2688

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
18%17%6%10%9%35%44415%
1432
16th to endDay
12%18%12%12%10%5%5%32412%
1536
February1st to 15thDay
13%15%8%12%9%45%44416%
1696
16th to endDay
16%12%8%13%6%45%445%17%
1580
March1st to 15thDay
17%12%6%8%6%25%45%7%24%
1818
16th to endDay
19%8%46%5%34446%30%
2168
April1st to 15thDay
20%12%35%423346%32%
2151
16th to endDay
17%8%25%42435%7%37%
2298
May1st to 15thDay
20%8%36%43445%7%31%
2331
16th to endDay
12%5%36%5%36%448%39%
2533
June1st to 15thDay
10%5%25%6%245%5%7%43%
2520
16th to endDay
8%5%245%46%6%7%8%39%
2520
July1st to 15thDay
6%5%25%4445%5%9%44%
2520
16th to endDay
6%4245%36%6%7%10%42%
2652
August1st to 15thDay
6%325%5%36%6%7%10%42%
2340
16th to endDay
11%5%245%345%5%8%42%
2345
September1st to 15thDay
12%5%2443445%7%45%
2082
16th to endDay
12%5%25%5%345%7%9%40%
1881
October1st to 15thDay
13%7%26%5%2445%6%39%
1799
16th to endDay
21%8%36%6%25%35%7%29%
1587
November1st to 15thDay
14%9%35%6%3345%6%37%
1582
16th to endDay
20%16%6%8%5%34345%21%
1620
December1st to 15thDay
16%19%11%9%5%3333418%
1503
16th to endDay
21%16%9%11%6%3344413%
1536
January1st to 15thNight
20%14%6%10%7%34445%19%
2506
16th to endNight
14%14%8%11%9%5%4446%16%
2687
February1st to 15thNight
16%12%6%10%7%3435%6%22%
2154
16th to endNight
16%11%6%10%6%45%45%5%23%
1893
March1st to 15thNight
17%10%47%5%33435%33%
2142
16th to endNight
16%7%46%5%36%446%34%
2064
April1st to 15thNight
19%8%35%5%35%447%33%
1797
16th to endNight
18%6%245%24445%39%
1662
May1st to 15thNight
19%7%25%425%45%7%33%
1619
16th to endNight
13%5%243345%5%8%43%
1577
June1st to 15thNight
10%4245%2445%9%46%
1440
16th to endNight
8%5%235%346%7%10%42%
1440
July1st to 15thNight
5%215%425%5%5%8%52%
1440
16th to endNight
6%313435%36%9%52%
1516
August1st to 15thNight
5%314425%5%6%8%51%
1620
16th to endNight
10%415%434448%48%
1856
September1st to 15thNight
11%41333335%6%51%
1866
16th to endNight
12%424433447%48%
1892
October1st to 15thNight
14%6%14424447%45%
1831
16th to endNight
22%9%36%423335%34%
2282
November1st to 15thNight
15%9%36%5%2345%5%39%
2276
16th to endNight
19%15%5%8%5%34346%23%
2340
December1st to 15thNight
21%16%8%9%6%3434417%
2456
16th to endNight
23%16%7%10%7%45%435%12%
2688

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
71%412%8%2
1433
16th to endDay
77%38%7%3
1536
February1st to 15thDay
69%48%11%5%1
1698
16th to endDay
67%410%11%5%
1580
March1st to 15thDay
60%413%14%7%
1818
16th to endDay
54%412%21%6%
2169
April1st to 15thDay
53%49%19%12%
2151
16th to endDay
46%412%19%13%4
2298
May1st to 15thDay
52%411%21%9%
2331
16th to endDay
42%5%11%25%13%1
2537
June1st to 15thDay
38%5%11%25%18%
2520
16th to endDay
38%7%13%20%16%2
2520
July1st to 15thDay
36%5%10%23%20%3
2371
16th to endDay
33%7%14%25%16%2
2485
August1st to 15thDay
34%6%13%25%17%2
2327
16th to endDay
39%5%12%23%16%3
2345
September1st to 15thDay
37%413%23%18%2
2082
16th to endDay
39%410%27%17%
1881
October1st to 15thDay
45%311%23%15%1
1799
16th to endDay
55%312%19%8%
1587
November1st to 15thDay
46%311%22%14%1
1582
16th to endDay
65%311%15%3
1620
December1st to 15thDay
69%310%12%3
1503
16th to endDay
74%411%7%2
1536
January1st to 15thNight
67%310%12%4
2506
16th to endNight
68%413%11%1
2687
February1st to 15thNight
63%312%14%5%
2163
16th to endNight
61%411%17%4
1893
March1st to 15thNight
53%413%18%9%1
2142
16th to endNight
51%312%22%8%1
2064
April1st to 15thNight
51%310%19%14%
1797
16th to endNight
45%49%20%15%3
1662
May1st to 15thNight
49%411%21%10%1
1620
16th to endNight
38%5%15%24%14%2
1579
June1st to 15thNight
34%412%28%17%1
1440
16th to endNight
35%6%18%22%15%1
1440
July1st to 15thNight
28%6%14%26%19%3
1360
16th to endNight
28%6%15%24%20%4
1420
August1st to 15thNight
28%6%12%28%21%2
1609
16th to endNight
34%5%9%24%21%4
1856
September1st to 15thNight
32%39%27%22%3
1866
16th to endNight
36%39%28%21%1
1892
October1st to 15thNight
39%49%26%19%1
1831
16th to endNight
52%211%23%9%
2282
November1st to 15thNight
46%311%22%13%2
2276
16th to endNight
62%312%16%4
2340
December1st to 15thNight
70%39%13%3
2456
16th to endNight
74%310%9%2
2688

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%15%36%17%10%
90
16th to endDay
25%9%38%20%5%1
96
February1st to 15thDay
20%18%40%14%6%
90
16th to endDay
20%12%38%19%8%
81
March1st to 15thDay
31%14%23%24%6%
108
16th to endDay
29%6%31%20%9%2
288
April1st to 15thDay
27%8%28%25%7%1
270
16th to endDay
20%7%34%18%13%5%
270
May1st to 15thDay
27%7%25%22%12%5%
288
16th to endDay
15%7%27%26%15%6%
433
June1st to 15thDay
12%5%28%31%16%5%
495
16th to endDay
12%7%29%28%16%6%
495
July1st to 15thDay
9%226%26%21%12%
475
16th to endDay
7%117%35%25%12%
512
August1st to 15thDay
7%113%29%28%19%
313
16th to endDay
14%212%27%27%14%
332
September1st to 15thDay
14%215%23%29%14%
315
16th to endDay
16%413%21%33%9%
278
October1st to 15thDay
15%9%21%29%19%4
255
16th to endDay
22%11%34%28%4
99
November1st to 15thDay
6%11%26%32%15%7%
90
16th to endDay
25%11%45%13%4
90
December1st to 15thDay
26%23%30%14%5%
90
16th to endDay
23%23%44%5%2
96
January1st to 15thNight
27%13%34%20%4
900
16th to endNight
19%11%36%28%4
959
February1st to 15thNight
22%9%37%25%3
704
16th to endNight
22%10%31%29%6%
631
March1st to 15thNight
24%9%32%25%8%
720
16th to endNight
19%9%30%32%8%
720
April1st to 15thNight
22%8%32%29%6%
539
16th to endNight
22%5%32%29%8%1
540
May1st to 15thNight
24%327%34%10%
540
16th to endNight
16%224%38%17%
563
June1st to 15thNight
12%223%45%16%
540
16th to endNight
10%121%42%23%1
540
July1st to 15thNight
8%116%44%26%2
510
16th to endNight
6%113%39%35%3
564
August1st to 15thNight
7%10%48%28%4
539
16th to endNight
11%112%33%35%5%
573
September1st to 15thNight
14%114%35%28%5%
606
16th to endNight
15%217%31%27%5%
685
October1st to 15thNight
18%5%22%33%19%1
660
16th to endNight
26%10%32%23%7%
704
November1st to 15thNight
21%9%30%26%11%1
700
16th to endNight
28%10%30%23%6%
720
December1st to 15thNight
27%12%33%21%4
836
16th to endNight
31%11%33%19%3
960
Page generated at 2017-09-23 06:43:40. Version ac04

Copyright 2017 A. Danko


Dr. T. K. Lawless Park Clear Sky Chart | Charts Home