Mansfield Dam
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mansfield Dam clear sky chart from 2005-11-05 to 2018-02-14.

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
49%
16082
26%
48788
18%
16036
57%
16036
34%
28282

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
38%
973
27%
2522
12%
970
46%
970
33%
1568
January16th to endNight
36%
981
30%
2645
13%
981
47%
981
33%
1631
February1st to 15thNight
32%
760
28%
2274
11%
754
45%
754
29%
1351
February16th to endNight
24%
632
29%
1894
8%
632
40%
632
30%
1103
March1st to 15thNight
32%
549
27%
1989
14%
549
47%
549
24%
1177
March16th to endNight
32%
576
24%
2112
15%
576
44%
576
25%
1216
April1st to 15thNight
29%
539
22%
1977
12%
539
44%
539
25%
1140
April16th to endNight
28%
540
25%
1761
12%
540
46%
540
25%
1089
May1st to 15thNight
35%
539
22%
1619
15%
539
45%
539
28%
998
May16th to endNight
48%
562
24%
1684
19%
561
59%
561
34%
995
June1st to 15thNight
66%
540
23%
1620
22%
540
73%
540
50%
803
June16th to endNight
67%
540
22%
1620
22%
540
71%
540
38%
935
July1st to 15thNight
74%
510
22%
1530
22%
510
79%
510
46%
804
July16th to endNight
81%
564
26%
1594
28%
531
85%
531
46%
835
August1st to 15thNight
89%
539
30%
1640
33%
536
90%
536
55%
772
August16th to endNight
76%
573
21%
1979
25%
573
77%
573
31%
1129
September1st to 15thNight
76%
540
20%
1980
24%
540
77%
540
32%
1115
September16th to endNight
69%
537
26%
1980
28%
537
72%
537
29%
1110
October1st to 15thNight
69%
560
32%
2000
30%
560
73%
560
38%
1010
October16th to endNight
57%
768
36%
2304
23%
768
66%
768
48%
1158
November1st to 15thNight
51%
770
26%
2290
17%
770
57%
770
33%
1367
November16th to endNight
46%
975
32%
2535
15%
975
54%
975
39%
1512
December1st to 15thNight
39%
975
27%
2535
15%
975
45%
975
31%
1657
December16th to endNight
35%
1040
23%
2704
11%
1040
42%
1040
28%
1807

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%2442445%7%46%
49275
Night
11%423323347%53%
48991
Cloud CoverDay
12%5%2442445%7%47%
49273
Night
11%423323347%53%
48991
TransparencyDay
37%5%10%19%18%9%
48973
Night
31%5%11%20%19%11%
48796
SeeingDay
12%5%19%32%24%5%
5855
Night
14%6%26%35%16%1
16086

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
16%423323325%51%
1746
16th to endDay
15%423322235%52%
1940
February1st to 15thDay
15%7%2431323451%
1882
16th to endDay
17%6%23222245%50%
1580
March1st to 15thDay
21%5%24313335%45%
1970
16th to endDay
15%5%24323346%48%
2112
April1st to 15thDay
12%6%25%42445%6%44%
1971
16th to endDay
13%6%34424446%44%
2196
May1st to 15thDay
15%6%35%6%3445%6%38%
2331
16th to endDay
14%6%25%5%35%6%6%7%36%
2430
June1st to 15thDay
4314436%6%7%8%47%
2340
16th to endDay
9%435%5%36%7%7%9%37%
2340
July1st to 15thDay
8%4245%45%7%7%8%41%
2340
16th to endDay
7%3245%35%5%6%9%46%
2466
August1st to 15thDay
121233435%10%60%
2307
16th to endDay
7%326%5%46%6%6%11%40%
2220
September1st to 15thDay
10%5%25%6%35%5%6%7%42%
1980
16th to endDay
9%425%5%345%6%7%45%
1980
October1st to 15thDay
10%324424346%53%
1947
16th to endDay
7%31222233465%
1920
November1st to 15thDay
12%6%25%5%23446%46%
1895
16th to endDay
13%413213335%56%
1755
December1st to 15thDay
18%6%25%313345%45%
1755
16th to endDay
17%7%24423335%43%
1872
January1st to 15thNight
15%5%24213235%52%
2522
16th to endNight
15%5%13312335%51%
2645
February1st to 15thNight
16%5%24312225%53%
2270
16th to endNight
13%5%23223335%52%
1894
March1st to 15thNight
17%6%14323335%48%
1989
16th to endNight
13%423324346%50%
2112
April1st to 15thNight
12%5%24323346%49%
1977
16th to endNight
14%6%34423437%45%
1761
May1st to 15thNight
11%5%25%4245%5%8%46%
1619
16th to endNight
9%42332445%10%48%
1683
June1st to 15thNight
31222345%10%62%
1620
16th to endNight
6%31342446%10%53%
1620
July1st to 15thNight
5%21231346%13%55%
1620
16th to endNight
421232445%12%57%
1702
August1st to 15thNight
21111335%10%66%
1650
16th to endNight
7%225%4345%6%9%48%
1979
September1st to 15thNight
7%4244345%6%8%49%
1980
16th to endNight
10%41443445%6%50%
1980
October1st to 15thNight
8%313222346%60%
2000
16th to endNight
8%212212335%65%
2304
November1st to 15thNight
10%5%2332435%6%52%
2290
16th to endNight
11%5%13322235%58%
2535
December1st to 15thNight
14%7%34313445%48%
2535
16th to endNight
17%7%2441343446%
2704

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
16%423323325%51%
1746
16th to endDay
15%423422335%53%
1940
February1st to 15thDay
15%7%2432333451%
1882
16th to endDay
16%6%23313245%50%
1580
March1st to 15thDay
21%5%24313335%45%
1970
16th to endDay
15%5%24313346%48%
2110
April1st to 15thDay
13%6%2442445%6%44%
1971
16th to endDay
13%6%35%424446%44%
2196
May1st to 15thDay
15%6%346%3445%6%38%
2331
16th to endDay
14%6%25%5%35%5%6%7%36%
2430
June1st to 15thDay
5%314436%7%7%8%48%
2340
16th to endDay
9%425%5%46%7%7%9%37%
2340
July1st to 15thDay
8%3245%45%6%8%8%41%
2340
16th to endDay
7%3245%345%6%9%46%
2466
August1st to 15thDay
121233445%10%60%
2307
16th to endDay
7%326%5%36%6%6%10%40%
2220
September1st to 15thDay
10%5%25%6%35%5%5%7%42%
1980
16th to endDay
9%425%5%345%6%7%45%
1980
October1st to 15thDay
10%423424346%53%
1947
16th to endDay
7%313222335%65%
1920
November1st to 15thDay
11%6%25%5%23445%46%
1895
16th to endDay
13%423223335%56%
1755
December1st to 15thDay
18%7%25%313345%45%
1755
16th to endDay
17%7%24423435%43%
1872
January1st to 15thNight
16%5%24213235%52%
2522
16th to endNight
15%5%23312346%51%
2645
February1st to 15thNight
16%5%23212225%54%
2270
16th to endNight
14%5%23323335%53%
1894
March1st to 15thNight
17%5%13323345%48%
1989
16th to endNight
13%423324346%49%
2112
April1st to 15thNight
12%5%24423446%49%
1977
16th to endNight
14%6%24423437%45%
1761
May1st to 15thNight
10%5%25%4245%5%7%46%
1619
16th to endNight
9%41332446%10%48%
1683
June1st to 15thNight
32222345%10%62%
1620
16th to endNight
6%21342445%10%53%
1620
July1st to 15thNight
5%11231346%13%55%
1620
16th to endNight
421231445%12%57%
1702
August1st to 15thNight
21111326%10%66%
1650
16th to endNight
7%325%425%5%6%9%48%
1979
September1st to 15thNight
7%42432446%9%49%
1980
16th to endNight
10%41443345%6%50%
1980
October1st to 15thNight
9%313222346%60%
2000
16th to endNight
8%212213335%65%
2304
November1st to 15thNight
10%5%1332435%6%52%
2290
16th to endNight
12%5%13322235%58%
2535
December1st to 15thNight
14%7%34313345%48%
2535
16th to endNight
17%7%3441333446%
2704

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%36%18%22%11%
1747
16th to endDay
35%35%13%27%15%
1940
February1st to 15thDay
37%36%15%21%14%
1883
16th to endDay
38%36%18%20%13%
1580
March1st to 15thDay
42%37%12%21%12%
1970
16th to endDay
38%5%7%16%22%9%
2112
April1st to 15thDay
40%5%7%15%17%12%
1971
16th to endDay
41%5%6%18%17%11%
2196
May1st to 15thDay
45%5%9%13%17%7%
2331
16th to endDay
44%8%11%16%15%3
2434
June1st to 15thDay
31%7%12%22%20%5%
2340
16th to endDay
40%9%12%20%14%2
2340
July1st to 15thDay
35%8%15%25%13%1
2201
16th to endDay
31%7%18%28%12%
2311
August1st to 15thDay
18%7%17%36%18%1
2293
16th to endDay
37%9%15%23%10%3
2220
September1st to 15thDay
39%7%12%19%14%6%
1980
16th to endDay
36%7%10%18%17%8%
1980
October1st to 15thDay
32%5%10%20%18%14%
1947
16th to endDay
22%35%15%30%21%
1920
November1st to 15thDay
40%5%8%19%16%10%
1895
16th to endDay
33%26%15%22%19%
1755
December1st to 15thDay
43%27%16%20%9%
1755
16th to endDay
43%49%14%18%9%
1872
January1st to 15thNight
35%25%17%21%17%
2522
16th to endNight
35%3414%23%17%
2645
February1st to 15thNight
36%35%14%21%18%
2280
16th to endNight
34%36%16%21%16%
1894
March1st to 15thNight
38%48%12%21%14%
1989
16th to endNight
36%410%15%21%11%
2112
April1st to 15thNight
37%48%16%17%16%
1977
16th to endNight
40%5%9%17%16%11%
1761
May1st to 15thNight
36%6%11%19%16%8%
1620
16th to endNight
30%7%16%25%15%3
1685
June1st to 15thNight
17%6%15%26%28%4
1620
16th to endNight
25%10%15%28%16%3
1620
July1st to 15thNight
20%7%23%33%14%1
1530
16th to endNight
20%7%25%35%11%
1594
August1st to 15thNight
13%7%21%37%18%1
1640
16th to endNight
30%8%20%26%10%3
1979
September1st to 15thNight
30%7%16%23%15%6%
1980
16th to endNight
32%6%13%21%16%8%
1980
October1st to 15thNight
25%5%12%24%19%13%
2000
16th to endNight
22%26%17%26%24%
2304
November1st to 15thNight
32%5%10%19%18%12%
2290
16th to endNight
31%36%15%22%20%
2535
December1st to 15thNight
39%37%18%19%10%
2535
16th to endNight
42%36%13%21%12%
2704

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
17%10%37%25%8%
135
16th to endDay
18%13%34%27%6%
144
February1st to 15thDay
16%14%33%27%6%
130
16th to endDay
18%19%35%22%3
81
March1st to 15thDay
31%13%30%14%10%1
90
16th to endDay
12%8%38%32%7%1
96
April1st to 15thDay
13%13%43%23%6%
90
16th to endDay
15%13%38%21%10%
306
May1st to 15thDay
17%10%37%25%8%
468
16th to endDay
22%5%25%30%14%1
517
June1st to 15thDay
7%14%47%25%4
495
16th to endDay
8%113%38%27%9%
495
July1st to 15thDay
6%11%43%31%7%
475
16th to endDay
6%433%47%8%
515
August1st to 15thDay
3433%46%12%
460
16th to endDay
14%5%37%30%11%
260
September1st to 15thDay
27%21%54%14%
135
16th to endDay
14%224%43%14%
135
October1st to 15thDay
19%29%42%15%
135
16th to endDay
13%7%16%28%26%6%
144
November1st to 15thDay
28%221%34%11%2
135
16th to endDay
18%7%26%30%14%2
135
December1st to 15thDay
20%5%33%20%12%6%
135
16th to endDay
31%15%25%21%4
144
January1st to 15thNight
19%11%27%31%9%
975
16th to endNight
18%8%33%32%6%
981
February1st to 15thNight
20%12%32%28%6%
760
16th to endNight
18%13%42%24%1
632
March1st to 15thNight
19%8%35%30%4
549
16th to endNight
13%13%37%29%4
576
April1st to 15thNight
15%9%43%30%1
539
16th to endNight
17%9%43%22%7%
540
May1st to 15thNight
14%8%38%32%6%
540
16th to endNight
11%433%34%15%
563
June1st to 15thNight
424%48%19%1
540
16th to endNight
6%18%50%21%2
540
July1st to 15thNight
5%14%48%28%3
510
16th to endNight
46%54%29%3
564
August1st to 15thNight
2451%36%4
539
16th to endNight
8%5%46%36%3
573
September1st to 15thNight
9%7%39%37%6%
540
16th to endNight
10%9%37%39%3
537
October1st to 15thNight
9%215%39%28%5%
560
16th to endNight
9%425%32%25%1
768
November1st to 15thNight
13%427%34%18%1
770
16th to endNight
16%8%26%31%15%1
975
December1st to 15thNight
20%7%29%31%9%
975
16th to endNight
22%9%27%30%8%
1040
Page generated at 2018-02-15 09:58:41. Version ac04

Copyright 2018 A. Danko


Mansfield Dam Clear Sky Chart |Charts Home