Lovell
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lovell clear sky chart from 2005-11-05 to 2017-12-01.

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
58%
16462
19%
47834
15%
16423
61%
16423
33%
28886

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
50%
896
12%
2506
9%
895
53%
895
25%
1687
January16th to endNight
55%
822
17%
2550
15%
822
59%
822
27%
1618
February1st to 15thNight
50%
697
10%
2288
9%
697
53%
697
23%
1492
February16th to endNight
47%
632
11%
2018
9%
632
50%
632
23%
1325
March1st to 15thNight
58%
720
16%
2016
10%
720
62%
720
35%
1229
March16th to endNight
52%
756
14%
2100
10%
756
55%
756
28%
1402
April1st to 15thNight
49%
539
15%
1798
13%
539
54%
539
24%
1138
April16th to endNight
51%
540
16%
1668
14%
540
53%
540
26%
1066
May1st to 15thNight
58%
539
17%
1501
14%
539
59%
539
33%
932
May16th to endNight
60%
563
14%
1498
12%
561
62%
561
31%
991
June1st to 15thNight
55%
540
12%
1440
9%
540
56%
540
30%
953
June16th to endNight
67%
540
20%
1440
13%
540
71%
540
54%
743
July1st to 15thNight
77%
510
18%
1360
15%
510
79%
510
56%
689
July16th to endNight
75%
564
28%
1441
25%
531
78%
531
63%
688
August1st to 15thNight
76%
539
25%
1611
23%
536
78%
536
50%
787
August16th to endNight
74%
573
32%
1791
30%
573
76%
573
49%
867
September1st to 15thNight
69%
540
28%
1800
28%
540
74%
540
42%
906
September16th to endNight
68%
677
30%
1983
25%
677
71%
677
46%
1032
October1st to 15thNight
53%
720
22%
2160
17%
720
58%
720
32%
1301
October16th to endNight
63%
768
30%
2304
22%
768
69%
768
40%
1267
November1st to 15thNight
55%
947
22%
2609
16%
947
59%
947
34%
1619
November16th to endNight
54%
975
21%
2730
15%
975
59%
975
34%
1652
December1st to 15thNight
51%
905
11%
2534
7%
905
54%
905
27%
1681
December16th to endNight
51%
960
15%
2688
10%
960
56%
960
26%
1821

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
5%5%245%35%5%7%8%45%
48609
Night
5%5%25%5%35%5%6%8%44%
48006
Cloud CoverDay
5%5%245%35%5%6%9%46%
48609
Night
5%5%25%5%35%5%6%9%44%
48008
TransparencyDay
31%5%17%26%14%4
48285
Night
33%5%18%25%12%3
47834
SeeingDay
8%6%23%35%21%4
6259
Night
8%419%47%18%1
16474

By Month

Percentage Cloud Cover NW (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
37%36%6%5%8%10%10%11%26%
1433
16th to endDay
28%46%6%5%6%7%6%9%36%
1686
February1st to 15thDay
39%48%6%46%6%9%9%29%
1575
16th to endDay
48%26%7%47%6%8%10%32%
1455
March1st to 15thDay
25%24435%5%6%11%46%
1944
16th to endDay
6%8%26%6%36%6%7%9%36%
2123
April1st to 15thDay
7%6%35%5%35%5%7%10%39%
2150
16th to endDay
8%6%27%6%35%6%7%9%36%
2289
May1st to 15thDay
7%6%35%4245%5%9%44%
2448
16th to endDay
11%6%246%35%6%7%9%34%
2616
June1st to 15thDay
7%425%5%35%6%7%9%43%
2520
16th to endDay
211222446%9%60%
2520
July1st to 15thDay
21133245%7%9%56%
2520
16th to endDay
21123235%7%7%61%
2626
August1st to 15thDay
32123245%8%8%55%
2340
16th to endDay
321232325%7%63%
2411
September1st to 15thDay
7%312223346%62%
2160
16th to endDay
6%312323446%59%
1973
October1st to 15thDay
10%8%2442435%6%46%
1800
16th to endDay
5%5%235%4445%8%50%
1911
November1st to 15thDay
5%5%26%5%25%5%6%7%47%
1573
16th to endDay
37%26%6%25%5%6%10%43%
1560
December1st to 15thDay
5%8%46%6%5%9%7%8%10%27%
1440
16th to endDay
47%47%8%5%8%7%8%9%27%
1536
January1st to 15thNight
48%37%6%47%7%8%9%30%
2506
16th to endNight
47%47%6%36%7%8%10%34%
2550
February1st to 15thNight
48%48%7%46%7%7%9%30%
2277
16th to endNight
37%49%7%47%5%7%9%32%
2018
March1st to 15thNight
36%25%5%36%5%7%12%41%
2016
16th to endNight
7%8%36%5%46%5%7%8%38%
2097
April1st to 15thNight
8%8%35%5%245%5%7%42%
1798
16th to endNight
8%7%25%7%35%47%9%37%
1668
May1st to 15thNight
8%7%34325%45%7%47%
1500
16th to endNight
11%425%4346%6%9%40%
1498
June1st to 15thNight
8%425%5%36%5%6%8%41%
1440
16th to endNight
221222436%7%62%
1440
July1st to 15thNight
1122245%7%10%60%
1440
16th to endNight
311231235%7%67%
1539
August1st to 15thNight
31124245%7%9%58%
1620
16th to endNight
4213323347%62%
1791
September1st to 15thNight
7%213323345%61%
1800
16th to endNight
9%313223337%59%
1983
October1st to 15thNight
12%5%25%4145%5%6%46%
2160
16th to endNight
34244345%47%54%
2304
November1st to 15thNight
46%35%5%245%5%8%47%
2609
16th to endNight
5%6%35%5%35%5%6%8%44%
2730
December1st to 15thNight
47%37%8%5%6%7%9%9%30%
2534
16th to endNight
47%48%7%46%7%7%11%29%
2688

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
35%37%7%5%7%9%10%11%27%
1432
16th to endDay
28%36%6%45%6%8%10%36%
1686
February1st to 15thDay
37%49%6%46%7%8%11%30%
1575
16th to endDay
38%36%6%47%6%7%10%34%
1455
March1st to 15thDay
25%245%36%5%6%11%47%
1944
16th to endDay
6%7%36%5%35%6%7%10%36%
2124
April1st to 15thDay
6%6%25%5%25%6%7%9%40%
2150
16th to endDay
7%6%36%6%35%6%7%8%37%
2289
May1st to 15thDay
6%6%25%5%35%5%5%8%45%
2448
16th to endDay
11%6%246%36%6%7%9%35%
2616
June1st to 15thDay
7%3245%35%5%7%9%44%
2520
16th to endDay
21232446%9%60%
2520
July1st to 15thDay
2112425%5%7%10%57%
2520
16th to endDay
21123345%6%8%61%
2626
August1st to 15thDay
32123246%7%9%55%
2340
16th to endDay
3213313349%63%
2411
September1st to 15thDay
6%312323346%62%
2160
16th to endDay
6%313323447%59%
1973
October1st to 15thDay
10%8%2433435%6%46%
1800
16th to endDay
5%4145%35%45%7%51%
1911
November1st to 15thDay
6%425%5%2447%8%48%
1573
16th to endDay
46%25%5%346%6%10%44%
1560
December1st to 15thDay
5%6%37%7%38%8%9%11%28%
1440
16th to endDay
37%46%8%5%8%7%8%12%27%
1536
January1st to 15thNight
48%37%6%47%6%8%10%30%
2506
16th to endNight
48%36%6%36%6%8%10%35%
2550
February1st to 15thNight
48%37%8%46%7%8%10%30%
2277
16th to endNight
37%49%8%47%6%7%9%33%
2018
March1st to 15thNight
35%35%445%5%8%12%41%
2016
16th to endNight
8%8%35%5%35%47%9%37%
2100
April1st to 15thNight
8%7%35%5%35%5%6%6%42%
1798
16th to endNight
7%7%25%6%46%46%9%39%
1668
May1st to 15thNight
9%7%34325%35%7%47%
1500
16th to endNight
11%5%346%345%7%8%40%
1497
June1st to 15thNight
8%5%25%6%46%5%6%7%41%
1440
16th to endNight
221222345%9%62%
1440
July1st to 15thNight
11221446%13%58%
1440
16th to endNight
221231235%8%67%
1539
August1st to 15thNight
2133245%8%9%57%
1620
16th to endNight
4213324447%62%
1791
September1st to 15thNight
7%313323246%61%
1800
16th to endNight
8%412323336%59%
1983
October1st to 15thNight
11%6%244235%5%7%46%
2160
16th to endNight
34244345%47%55%
2304
November1st to 15thNight
5%6%25%5%245%6%8%47%
2609
16th to endNight
5%6%25%5%45%5%6%8%45%
2730
December1st to 15thNight
46%37%7%5%7%6%9%10%31%
2534
16th to endNight
47%38%8%47%6%8%11%30%
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
39%9%27%18%4
1433
16th to endDay
37%5%25%24%5%1
1686
February1st to 15thDay
42%6%22%22%4
1575
16th to endDay
40%6%25%19%7%1
1455
March1st to 15thDay
28%5%28%29%7%
1944
16th to endDay
38%6%21%27%5%
2124
April1st to 15thDay
36%6%21%26%8%
2150
16th to endDay
40%5%18%27%8%
2289
May1st to 15thDay
35%5%16%31%9%1
2448
16th to endDay
40%7%21%21%8%
2620
June1st to 15thDay
31%5%20%26%13%1
2520
16th to endDay
18%412%29%23%11%
2520
July1st to 15thDay
20%5%9%29%25%11%
2371
16th to endDay
18%37%22%27%20%
2461
August1st to 15thDay
22%48%30%21%12%
2325
16th to endDay
19%27%25%29%14%
2411
September1st to 15thDay
22%37%28%28%8%
2160
16th to endDay
24%314%32%22%3
1973
October1st to 15thDay
37%417%26%12%1
1800
16th to endDay
30%419%29%13%2
1911
November1st to 15thDay
31%5%18%28%14%1
1573
16th to endDay
33%5%26%26%8%
1560
December1st to 15thDay
42%8%26%20%2
1440
16th to endDay
42%7%25%19%4
1536
January1st to 15thNight
41%7%23%20%4
2506
16th to endNight
38%6%21%25%6%1
2550
February1st to 15thNight
43%6%22%21%6%
2288
16th to endNight
44%6%21%19%7%1
2018
March1st to 15thNight
32%6%25%26%8%
2016
16th to endNight
40%6%18%26%7%
2100
April1st to 15thNight
40%7%17%25%9%
1798
16th to endNight
39%6%18%25%9%
1668
May1st to 15thNight
35%416%27%13%2
1501
16th to endNight
37%7%23%21%9%
1498
June1st to 15thNight
38%7%17%23%12%1
1440
16th to endNight
19%213%31%22%9%
1440
July1st to 15thNight
16%5%13%31%23%10%
1360
16th to endNight
14%27%21%31%21%
1441
August1st to 15thNight
19%412%26%24%12%
1611
16th to endNight
20%37%25%26%16%
1791
September1st to 15thNight
24%48%22%27%12%
1800
16th to endNight
25%212%28%27%4
1983
October1st to 15thNight
35%413%30%12%3
2160
16th to endNight
27%416%33%14%3
2304
November1st to 15thNight
34%6%16%28%12%2
2609
16th to endNight
34%424%26%9%
2730
December1st to 15thNight
41%6%25%23%2
2534
16th to endNight
42%7%20%24%41
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
4110%41%31%12%
90
16th to endDay
10%5%57%21%5%
96
February1st to 15thDay
8%426%47%10%2
90
16th to endDay
6%332%46%9%1
81
March1st to 15thDay
47%34%36%15%2
234
16th to endDay
13%10%35%30%9%
288
April1st to 15thDay
10%10%43%25%9%
269
16th to endDay
15%14%31%27%10%1
270
May1st to 15thDay
9%8%25%33%20%3
405
16th to endDay
14%6%18%30%24%5%
517
June1st to 15thDay
7%8%22%33%24%4
495
16th to endDay
45%24%38%24%2
495
July1st to 15thDay
3318%33%35%5%
475
16th to endDay
2318%40%30%4
485
August1st to 15thDay
7%422%33%26%5%
315
16th to endDay
3319%31%30%11%
332
September1st to 15thDay
9%6%20%30%23%7%
315
16th to endDay
13%419%30%22%8%
272
October1st to 15thDay
11%8%25%40%13%1
135
16th to endDay
211%25%39%15%5%
144
November1st to 15thDay
11%215%42%18%9%
135
16th to endDay
14%5%30%42%5%
135
December1st to 15thDay
10%222%53%11%1
90
16th to endDay
7%212%57%18%2
96
January1st to 15thNight
6%6%21%48%14%2
900
16th to endNight
6%419%55%12%1
822
February1st to 15thNight
6%320%50%16%1
704
16th to endNight
6%326%49%12%2
632
March1st to 15thNight
6%222%50%16%1
720
16th to endNight
12%223%45%14%
756
April1st to 15thNight
11%5%22%45%12%
539
16th to endNight
10%7%23%44%12%1
540
May1st to 15thNight
13%6%16%41%19%2
540
16th to endNight
13%313%42%26%1
563
June1st to 15thNight
9%6%19%46%17%
540
16th to endNight
5%5%17%48%22%
540
July1st to 15thNight
2213%48%32%
510
16th to endNight
3212%48%31%1
564
August1st to 15thNight
429%45%36%2
539
16th to endNight
5%210%45%33%2
573
September1st to 15thNight
8%312%42%28%4
540
16th to endNight
11%212%41%28%3
677
October1st to 15thNight
15%418%41%17%2
720
16th to endNight
5%219%51%18%2
768
November1st to 15thNight
7%6%21%49%13%1
947
16th to endNight
8%423%51%11%
975
December1st to 15thNight
7%421%51%14%
905
16th to endNight
6%320%53%14%1
960
Page generated at 2017-12-02 07:14:18. Version ac04

Copyright 2017 A. Danko


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