Mantrap Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mantrap Lake clear sky chart from 2005-11-05 to 2017-09-24.

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
35%
16225
14%
46818
8%
16178
40%
16178
22%
32524

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
27%
900
11%
2685
6%
895
33%
895
15%
2032
January16th to endNight
21%
960
12%
2621
4%
960
28%
960
14%
2031
February1st to 15thNight
32%
879
15%
2288
5%
875
39%
875
22%
1635
February16th to endNight
30%
789
14%
2051
5%
789
37%
789
20%
1520
March1st to 15thNight
31%
567
14%
2007
10%
567
38%
567
18%
1368
March16th to endNight
31%
576
15%
2112
11%
576
39%
576
15%
1469
April1st to 15thNight
31%
539
16%
1776
11%
539
41%
539
21%
1184
April16th to endNight
32%
540
15%
1620
11%
540
38%
540
19%
1169
May1st to 15thNight
33%
540
13%
1503
6%
540
36%
540
21%
1069
May16th to endNight
40%
563
12%
1474
4%
561
44%
561
30%
990
June1st to 15thNight
43%
540
11%
1260
4%
540
47%
540
35%
843
June16th to endNight
52%
540
11%
1260
6%
540
54%
540
39%
799
July1st to 15thNight
59%
510
14%
1190
7%
510
61%
510
46%
742
July16th to endNight
59%
564
18%
1346
7%
531
60%
531
45%
794
August1st to 15thNight
64%
539
20%
1610
14%
536
68%
536
40%
886
August16th to endNight
52%
573
22%
1728
19%
573
59%
573
37%
968
September1st to 15thNight
55%
540
19%
1812
18%
540
62%
540
35%
1014
September16th to endNight
40%
527
20%
1922
16%
527
50%
527
27%
1111
October1st to 15thNight
35%
660
19%
1980
12%
660
41%
660
24%
1277
October16th to endNight
29%
744
13%
2152
5%
744
35%
744
18%
1539
November1st to 15thNight
28%
875
17%
2450
8%
875
36%
875
21%
1730
November16th to endNight
24%
900
13%
2520
7%
900
29%
900
16%
1894
December1st to 15thNight
22%
900
7%
2571
3%
900
26%
900
12%
2063
December16th to endNight
15%
960
9%
2880
2%
960
23%
960
9%
2397

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%8%36%6%35%45%7%34%
48121
Night
12%9%46%5%3445%7%36%
46974
Cloud CoverDay
14%8%36%6%35%45%7%33%
48131
Night
11%9%46%5%3445%7%35%
46977
Cloud CoverDay
14%8%36%6%35%45%7%33%
48132
Night
12%9%47%5%35%45%7%35%
46978
Cloud CoverDay
14%8%36%6%35%45%7%33%
48130
Night
11%9%47%6%3445%7%35%
46978
TransparencyDay
48%6%13%22%8%
47795
Night
46%6%13%23%9%
46818
SeeingDay
17%8%29%26%14%3
6220
Night
15%8%32%30%11%1
16226

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
9%12%6%7%6%46%5%9%9%21%
1253
16th to endDay
10%12%6%13%8%5%7%5%5%7%16%
1599
February1st to 15thDay
8%11%5%9%7%37%5%48%28%
1575
16th to endDay
11%12%5%8%8%45%6%5%7%24%
1428
March1st to 15thDay
15%10%49%6%35%45%6%29%
1945
16th to endDay
17%10%48%6%24446%29%
2112
April1st to 15thDay
14%10%37%5%345%46%34%
2169
16th to endDay
22%11%26%6%23445%29%
2340
May1st to 15thDay
22%10%35%5%24446%30%
2446
16th to endDay
18%5%35%5%25%5%5%7%35%
2638
June1st to 15thDay
16%6%35%5%35%5%6%7%34%
2700
16th to endDay
12%5%25%6%45%5%6%9%37%
2700
July1st to 15thDay
9%424435%5%5%8%44%
2700
16th to endDay
6%4245%45%5%6%10%44%
2725
August1st to 15thDay
10%425%5%36%5%6%8%40%
2340
16th to endDay
13%41442445%5%48%
2474
September1st to 15thDay
14%42443336%8%44%
2146
16th to endDay
15%7%25%423346%42%
1885
October1st to 15thDay
17%11%34423345%39%
1650
16th to endDay
23%11%5%5%433335%29%
1719
November1st to 15thDay
12%12%47%5%2345%435%
1407
16th to endDay
14%13%5%8%8%35%35%7%22%
1440
December1st to 15thDay
12%14%6%10%8%45%5%6%6%19%
1386
16th to endDay
12%16%8%12%10%45%5%3417%
1344
January1st to 15thNight
8%9%6%8%8%47%6%6%7%23%
2685
16th to endNight
10%12%6%10%8%35%5%7%8%20%
2621
February1st to 15thNight
6%10%5%6%6%36%6%6%8%32%
2285
16th to endNight
8%10%38%8%46%5%6%7%29%
2051
March1st to 15thNight
11%9%48%6%35%448%34%
1995
16th to endNight
15%10%37%6%35%336%34%
2112
April1st to 15thNight
15%9%445%23445%39%
1776
16th to endNight
20%9%35%5%23445%33%
1620
May1st to 15thNight
19%8%345%24335%37%
1503
16th to endNight
13%6%25%43445%8%41%
1472
June1st to 15thNight
12%42443446%7%46%
1260
16th to endNight
9%313425%5%5%11%48%
1260
July1st to 15thNight
6%313315%45%8%55%
1260
16th to endNight
5%213425%5%5%9%54%
1439
August1st to 15thNight
6%31242435%9%54%
1620
16th to endNight
10%313413347%56%
1728
September1st to 15thNight
9%314322447%53%
1812
16th to endNight
12%6%24324347%49%
1922
October1st to 15thNight
14%6%15%434446%43%
1980
16th to endNight
19%11%35%423446%33%
2152
November1st to 15thNight
12%10%5%7%5%24447%35%
2450
16th to endNight
13%11%5%9%6%25%5%5%6%28%
2520
December1st to 15thNight
10%14%6%10%8%46%6%6%6%19%
2571
16th to endNight
15%17%8%11%8%43345%16%
2880

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
8%13%6%7%7%46%6%8%9%21%
1254
16th to endDay
10%11%7%14%8%47%5%5%8%15%
1599
February1st to 15thDay
8%11%5%9%7%37%5%5%8%27%
1575
16th to endDay
10%11%5%8%7%5%6%7%5%7%24%
1428
March1st to 15thDay
15%10%48%7%3445%6%29%
1956
16th to endDay
17%10%48%6%24446%29%
2110
April1st to 15thDay
13%10%36%5%34446%34%
2169
16th to endDay
22%10%26%6%24445%29%
2340
May1st to 15thDay
22%9%35%6%34346%29%
2446
16th to endDay
17%6%245%35%447%35%
2638
June1st to 15thDay
16%7%35%435%5%6%8%33%
2700
16th to endDay
12%5%25%5%45%5%6%9%37%
2700
July1st to 15thDay
9%4245%35%46%9%44%
2700
16th to endDay
6%3245%36%5%7%9%44%
2725
August1st to 15thDay
10%5%25%5%35%5%6%8%40%
2340
16th to endDay
13%42442335%6%48%
2474
September1st to 15thDay
14%42443445%8%44%
2146
16th to endDay
14%7%35%5%23345%42%
1885
October1st to 15thDay
17%12%34423346%38%
1650
16th to endDay
22%12%46%433335%29%
1719
November1st to 15thDay
12%12%46%5%24445%35%
1407
16th to endDay
14%13%5%9%7%5%446%6%23%
1440
December1st to 15thDay
11%15%6%9%9%46%47%6%19%
1386
16th to endDay
12%17%7%12%11%45%5%25%16%
1344
January1st to 15thNight
8%9%6%9%8%47%7%6%7%23%
2685
16th to endNight
10%12%5%10%8%45%5%7%9%20%
2621
February1st to 15thNight
7%10%5%7%5%35%6%7%9%31%
2278
16th to endNight
7%10%48%7%5%5%6%6%6%29%
2051
March1st to 15thNight
11%9%47%5%345%48%33%
2007
16th to endNight
14%10%37%6%45%345%34%
2110
April1st to 15thNight
15%9%45%424445%39%
1776
16th to endNight
20%9%46%5%23445%33%
1620
May1st to 15thNight
18%9%35%5%25%345%37%
1502
16th to endNight
12%6%25%4245%5%9%40%
1473
June1st to 15thNight
12%5%144245%5%6%46%
1260
16th to endNight
8%313325%5%6%11%48%
1260
July1st to 15thNight
6%21232446%8%55%
1260
16th to endNight
5%2133245%5%9%54%
1439
August1st to 15thNight
6%32241445%9%54%
1620
16th to endNight
10%324313347%55%
1728
September1st to 15thNight
9%324423446%54%
1812
16th to endNight
13%5%34323447%49%
1922
October1st to 15thNight
14%6%15%424446%42%
1980
16th to endNight
18%10%46%423445%33%
2152
November1st to 15thNight
11%11%5%7%5%3445%6%35%
2450
16th to endNight
13%10%5%8%7%35%5%5%6%28%
2520
December1st to 15thNight
10%14%6%10%7%5%6%6%6%6%19%
2571
16th to endNight
14%17%8%12%8%44346%16%
2880

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
9%11%7%7%6%45%6%8%9%21%
1253
16th to endDay
10%12%7%12%8%5%7%5%5%8%15%
1599
February1st to 15thDay
8%10%6%8%7%37%5%5%6%28%
1575
16th to endDay
10%12%5%7%8%45%7%5%7%24%
1428
March1st to 15thDay
15%9%49%6%345%5%6%29%
1956
16th to endDay
17%10%48%7%34446%29%
2112
April1st to 15thDay
14%10%37%5%345%46%34%
2169
16th to endDay
22%11%26%5%23345%29%
2340
May1st to 15thDay
22%9%35%6%25%446%29%
2446
16th to endDay
18%5%25%5%35%5%5%7%35%
2638
June1st to 15thDay
16%6%36%5%25%5%6%7%33%
2700
16th to endDay
12%5%25%5%45%5%6%9%37%
2700
July1st to 15thDay
9%425%435%5%6%8%44%
2700
16th to endDay
6%425%5%36%5%6%10%44%
2725
August1st to 15thDay
11%425%6%35%6%6%8%39%
2340
16th to endDay
13%414424446%47%
2474
September1st to 15thDay
14%42443345%8%44%
2146
16th to endDay
15%7%35%423346%42%
1885
October1st to 15thDay
17%12%24423345%39%
1650
16th to endDay
23%11%5%6%433336%28%
1719
November1st to 15thDay
12%11%5%7%5%2345%5%35%
1407
16th to endDay
14%13%6%7%7%45%35%7%22%
1440
December1st to 15thDay
12%14%6%10%8%45%5%6%6%19%
1386
16th to endDay
13%16%8%11%10%45%43416%
1344
January1st to 15thNight
8%9%6%9%8%47%6%6%8%23%
2685
16th to endNight
10%12%5%10%8%35%5%7%9%20%
2621
February1st to 15thNight
7%10%5%7%6%36%6%6%8%31%
2278
16th to endNight
8%10%38%8%45%6%6%7%29%
2051
March1st to 15thNight
11%9%48%5%24448%34%
2007
16th to endNight
15%10%47%6%35%336%33%
2112
April1st to 15thNight
15%9%36%424346%39%
1776
16th to endNight
20%10%36%5%23445%33%
1620
May1st to 15thNight
19%8%35%5%24345%37%
1502
16th to endNight
12%6%25%44445%8%40%
1472
June1st to 15thNight
12%4244245%5%6%46%
1260
16th to endNight
9%314325%46%10%48%
1260
July1st to 15thNight
6%213325%45%8%55%
1260
16th to endNight
4313325%45%9%55%
1439
August1st to 15thNight
6%31333445%9%54%
1620
16th to endNight
10%314323347%55%
1728
September1st to 15thNight
9%314423448%52%
1812
16th to endNight
12%5%23423347%48%
1922
October1st to 15thNight
14%6%25%425%447%42%
1980
16th to endNight
19%11%35%43435%5%33%
2152
November1st to 15thNight
12%11%5%6%5%23447%35%
2450
16th to endNight
13%10%5%8%6%35%5%5%7%27%
2520
December1st to 15thNight
10%14%7%10%7%47%6%5%7%18%
2571
16th to endNight
15%16%8%12%8%44345%16%
2880

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
9%11%6%8%7%5%6%6%7%10%21%
1253
16th to endDay
10%13%8%12%8%47%5%5%8%15%
1599
February1st to 15thDay
8%10%6%9%7%37%5%46%28%
1575
16th to endDay
11%12%48%9%45%7%47%24%
1428
March1st to 15thDay
15%9%48%6%345%5%6%29%
1956
16th to endDay
16%12%37%6%34446%29%
2110
April1st to 15thDay
14%9%37%5%345%47%34%
2169
16th to endDay
22%11%35%6%23445%29%
2340
May1st to 15thDay
22%10%35%5%24446%29%
2446
16th to endDay
17%5%35%5%345%5%8%35%
2638
June1st to 15thDay
16%6%36%5%345%5%8%33%
2700
16th to endDay
12%5%25%5%46%5%6%9%37%
2700
July1st to 15thDay
9%425%435%5%6%8%44%
2700
16th to endDay
5%425%5%36%5%7%9%44%
2725
August1st to 15thDay
10%425%6%46%5%6%8%39%
2340
16th to endDay
13%42442445%6%47%
2474
September1st to 15thDay
13%5%145%2446%8%43%
2146
16th to endDay
14%7%36%433347%41%
1885
October1st to 15thDay
17%11%24423435%39%
1650
16th to endDay
24%10%5%6%434246%28%
1719
November1st to 15thDay
12%12%5%7%5%23445%35%
1407
16th to endDay
14%12%7%8%7%45%35%7%22%
1440
December1st to 15thDay
11%15%5%10%8%45%5%7%5%19%
1386
16th to endDay
13%15%8%11%10%45%43417%
1344
January1st to 15thNight
8%9%6%9%8%47%6%7%7%23%
2685
16th to endNight
10%12%5%10%8%45%47%9%20%
2621
February1st to 15thNight
6%10%5%7%6%36%6%6%7%31%
2278
16th to endNight
8%10%48%8%45%6%6%7%29%
2051
March1st to 15thNight
11%9%48%5%24448%34%
2007
16th to endNight
15%10%47%6%35%336%33%
2112
April1st to 15thNight
15%9%35%5%23446%38%
1776
16th to endNight
20%10%35%5%33445%33%
1620
May1st to 15thNight
19%9%35%424445%37%
1502
16th to endNight
12%6%35%5%2446%8%40%
1472
June1st to 15thNight
12%5%145%245%5%7%46%
1260
16th to endNight
8%3134345%5%11%47%
1260
July1st to 15thNight
6%31332446%8%55%
1260
16th to endNight
4223325%46%9%54%
1439
August1st to 15thNight
6%31332445%8%54%
1620
16th to endNight
9%314323348%55%
1728
September1st to 15thNight
9%414423447%53%
1812
16th to endNight
11%5%34424447%48%
1922
October1st to 15thNight
14%7%15%425%448%41%
1980
16th to endNight
19%10%35%434446%32%
2152
November1st to 15thNight
12%11%5%7%5%2445%6%35%
2450
16th to endNight
13%11%5%8%7%35%5%6%7%27%
2520
December1st to 15thNight
10%14%7%10%7%5%6%6%5%7%18%
2571
16th to endNight
15%17%7%12%8%44345%16%
2880

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
54%6%11%20%6%
1254
16th to endDay
65%5%10%13%5%
1599
February1st to 15thDay
53%6%13%18%8%
1576
16th to endDay
57%6%11%17%7%
1428
March1st to 15thDay
54%5%13%18%7%
1956
16th to endDay
56%412%22%4
2112
April1st to 15thDay
49%5%12%20%10%1
2169
16th to endDay
56%412%15%10%
2340
May1st to 15thDay
55%411%22%5%
2446
16th to endDay
46%6%11%23%10%
2642
June1st to 15thDay
46%7%17%22%6%
2700
16th to endDay
41%8%15%24%9%
2700
July1st to 15thDay
35%7%14%28%13%1
2541
16th to endDay
34%8%18%26%10%1
2555
August1st to 15thDay
38%8%14%28%8%2
2326
16th to endDay
35%5%16%27%13%
2474
September1st to 15thDay
38%416%32%8%
2146
16th to endDay
43%5%15%30%5%
1885
October1st to 15thDay
47%413%24%8%1
1650
16th to endDay
57%413%17%7%
1719
November1st to 15thDay
50%6%13%20%9%1
1407
16th to endDay
60%5%14%11%7%
1440
December1st to 15thDay
62%5%12%15%3
1386
16th to endDay
70%47%10%6%
1344
January1st to 15thNight
54%7%9%19%6%
2685
16th to endNight
57%6%10%17%7%
2621
February1st to 15thNight
46%6%12%24%8%
2288
16th to endNight
50%7%11%20%9%
2051
March1st to 15thNight
49%5%13%21%9%
2007
16th to endNight
52%5%13%21%6%
2112
April1st to 15thNight
46%411%24%11%1
1776
16th to endNight
52%5%10%18%12%1
1620
May1st to 15thNight
49%5%12%21%10%
1503
16th to endNight
40%6%14%23%13%1
1474
June1st to 15thNight
35%6%19%28%9%
1260
16th to endNight
29%7%21%28%10%2
1260
July1st to 15thNight
26%6%18%31%15%1
1190
16th to endNight
24%7%17%31%16%2
1346
August1st to 15thNight
26%5%15%36%13%2
1610
16th to endNight
28%5%15%32%15%2
1728
September1st to 15thNight
29%6%16%36%11%
1812
16th to endNight
36%5%14%34%9%
1922
October1st to 15thNight
41%6%12%29%10%
1980
16th to endNight
51%5%13%21%8%
2152
November1st to 15thNight
49%412%22%9%1
2450
16th to endNight
54%6%14%15%7%
2520
December1st to 15thNight
62%7%12%13%5%
2571
16th to endNight
69%48%12%4
2880

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
18%13%31%25%7%3
90
16th to endDay
19%8%28%34%8%1
96
February1st to 15thDay
20%18%40%20%1
90
16th to endDay
25%446%16%23
81
March1st to 15thDay
22%7%36%24%8%
90
16th to endDay
16%5%36%19%18%3
96
April1st to 15thDay
16%10%37%23%10%
288
16th to endDay
30%8%25%21%11%1
450
May1st to 15thDay
24%13%31%20%9%1
468
16th to endDay
19%10%28%25%11%3
517
June1st to 15thDay
17%9%33%26%10%3
495
16th to endDay
10%10%33%28%12%5%
495
July1st to 15thDay
11%6%24%28%23%6%
475
16th to endDay
6%7%28%30%21%4
515
August1st to 15thDay
11%420%32%26%4
493
16th to endDay
15%6%24%28%20%5%
514
September1st to 15thDay
10%328%34%19%2
301
16th to endDay
17%8%39%16%16%
114
October1st to 15thDay
20%7%34%24%7%5%
90
16th to endDay
29%10%20%26%12%1
96
November1st to 15thDay
13%7%33%28%15%1
90
16th to endDay
43%7%25%17%5%
90
December1st to 15thDay
15%442%28%8%
90
16th to endDay
20%8%40%20%5%4
96
January1st to 15thNight
13%11%34%28%9%2
900
16th to endNight
16%11%39%25%6%
960
February1st to 15thNight
13%11%31%32%9%1
880
16th to endNight
12%8%38%25%11%2
789
March1st to 15thNight
14%10%36%27%10%
567
16th to endNight
20%9%30%26%10%2
576
April1st to 15thNight
19%8%35%28%7%
539
16th to endNight
24%7%28%28%9%1
540
May1st to 15thNight
21%7%34%27%8%
540
16th to endNight
15%7%31%32%12%
563
June1st to 15thNight
14%5%31%37%11%
540
16th to endNight
10%5%27%41%14%1
540
July1st to 15thNight
8%324%42%20%1
510
16th to endNight
6%226%43%20%1
564
August1st to 15thNight
8%20%44%23%2
539
16th to endNight
10%426%34%22%1
573
September1st to 15thNight
10%424%36%21%1
540
16th to endNight
14%7%34%29%11%3
527
October1st to 15thNight
19%9%30%29%10%
660
16th to endNight
25%9%29%28%6%
744
November1st to 15thNight
17%10%34%28%8%
875
16th to endNight
17%13%34%23%9%
900
December1st to 15thNight
16%10%37%27%8%
900
16th to endNight
23%9%34%24%6%1
960
Page generated at 2017-09-25 08:02:18. Version ac04

Copyright 2017 A. Danko


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