Morgan Point Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Morgan Point Observatory clear sky chart from 2005-11-05 to

2017-09-12
.

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
41%
15707
24%
46981
14%
15660
50%
15660
28%
28300

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
22%
900
27%
2327
7%
895
36%
895
24%
1494
January16th to endNight
24%
960
27%
2496
7%
960
37%
960
29%
1541
February1st to 15thNight
22%
880
19%
2288
5%
876
30%
876
24%
1492
February16th to endNight
20%
612
25%
1874
7%
612
35%
612
23%
1130
March1st to 15thNight
28%
540
20%
1980
12%
540
39%
540
18%
1256
March16th to endNight
29%
576
16%
2112
13%
576
37%
576
18%
1366
April1st to 15thNight
28%
539
23%
1815
11%
539
45%
539
24%
1053
April16th to endNight
32%
540
22%
1800
14%
540
46%
540
24%
1098
May1st to 15thNight
39%
539
19%
1683
13%
539
47%
539
27%
1055
May16th to endNight
47%
563
17%
1684
14%
561
53%
561
27%
1082
June1st to 15thNight
67%
540
24%
1458
19%
540
72%
540
48%
798
June16th to endNight
66%
540
24%
1526
19%
540
72%
540
45%
823
July1st to 15thNight
67%
510
16%
1530
16%
510
69%
510
35%
891
July16th to endNight
81%
564
24%
1594
27%
531
83%
531
41%
867
August1st to 15thNight
76%
539
22%
1613
25%
536
78%
536
38%
914
August16th to endNight
72%
573
22%
1910
27%
573
74%
573
32%
1082
September1st to 15thNight
65%
530
25%
1767
25%
530
68%
530
32%
994
September16th to endNight
61%
528
28%
1826
25%
528
67%
528
32%
1010
October1st to 15thNight
49%
660
29%
1980
20%
660
57%
660
36%
1123
October16th to endNight
41%
704
32%
2112
18%
704
53%
704
35%
1172
November1st to 15thNight
38%
700
30%
2100
15%
700
52%
700
33%
1172
November16th to endNight
30%
810
26%
2400
12%
810
42%
810
25%
1476
December1st to 15thNight
27%
900
21%
2520
8%
900
38%
900
24%
1638
December16th to endNight
24%
960
23%
2586
8%
960
36%
960
21%
1773

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
10%5%25%5%35%45%7%43%
47658
Night
9%5%2442445%7%50%
47177
TransparencyDay
39%7%11%22%16%3
47358
Night
33%6%11%24%19%4
46982
SeeingDay
12%10%25%25%19%6%
5748
Night
13%13%27%26%16%2
15708

By Month

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
12%6%24323346%51%
1611
16th to endDay
9%5%345%2445%5%48%
1728
February1st to 15thDay
11%8%26%5%2333447%
1575
16th to endDay
11%7%46%5%24446%43%
1609
March1st to 15thDay
14%6%35%434446%42%
1980
16th to endDay
16%7%25%5%34435%40%
2110
April1st to 15thDay
10%5%245%25%5%6%5%45%
2132
16th to endDay
15%7%26%6%345%46%37%
2160
May1st to 15thDay
15%6%25%6%45%5%46%37%
2265
16th to endDay
11%6%36%6%35%6%6%8%35%
2430
June1st to 15thDay
7%4245%36%5%6%9%43%
2496
16th to endDay
4335%5%36%5%7%9%43%
2428
July1st to 15thDay
8%5%35%7%47%7%7%9%34%
2340
16th to endDay
5%4245%46%6%7%11%41%
2466
August1st to 15thDay
10%325%5%36%5%7%9%40%
2337
16th to endDay
7%3247%46%6%7%9%40%
2292
September1st to 15thDay
13%5%1443445%6%45%
2112
16th to endDay
11%425%42446%5%47%
1790
October1st to 15thDay
11%5%25%423345%51%
1650
16th to endDay
11%41432323458%
1760
November1st to 15thDay
7%5%14423346%57%
1758
16th to endDay
12%6%34324437%47%
1554
December1st to 15thDay
12%7%24424348%45%
1440
16th to endDay
11%9%35%42435%5%42%
1635
January1st to 15thNight
11%5%14423446%51%
2327
16th to endNight
9%5%24333245%54%
2496
February1st to 15thNight
11%6%25%423346%47%
2278
16th to endNight
9%42442445%6%50%
1874
March1st to 15thNight
14%7%35%42445%7%41%
1980
16th to endNight
15%7%345%24445%42%
2112
April1st to 15thNight
8%42442445%6%51%
1815
16th to endNight
12%5%2443436%7%46%
1800
May1st to 15thNight
12%5%144245%5%8%46%
1682
16th to endNight
9%423435%5%5%9%45%
1683
June1st to 15thNight
42322346%9%60%
1458
16th to endNight
421231446%11%56%
1526
July1st to 15thNight
4424435%46%9%49%
1620
16th to endNight
42133245%5%9%56%
1702
August1st to 15thNight
5%313335%5%6%9%51%
1623
16th to endNight
4325%5%35%48%10%47%
1910
September1st to 15thNight
10%41332335%8%51%
1767
16th to endNight
8%5%14424336%54%
1826
October1st to 15thNight
9%41432335%6%56%
1980
16th to endNight
11%41331323460%
2112
November1st to 15thNight
7%424333345%58%
2100
16th to endNight
13%5%23423345%50%
2400
December1st to 15thNight
11%5%25%424447%45%
2520
16th to endNight
12%9%35%5%2344443%
2586

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
36%47%26%20%4
1612
16th to endDay
36%48%27%19%4
1728
February1st to 15thDay
42%410%23%15%3
1576
16th to endDay
42%6%9%22%16%4
1609
March1st to 15thDay
43%6%9%18%15%6%
1980
16th to endDay
47%6%10%21%12%1
2112
April1st to 15thDay
40%7%10%20%18%2
2132
16th to endDay
47%7%8%17%15%2
2160
May1st to 15thDay
48%6%9%18%14%1
2265
16th to endDay
45%9%11%21%10%
2434
June1st to 15thDay
36%9%13%25%15%
2496
16th to endDay
34%9%15%24%14%2
2428
July1st to 15thDay
42%9%13%24%8%1
2201
16th to endDay
33%9%17%27%11%1
2311
August1st to 15thDay
36%10%14%22%14%1
2323
16th to endDay
37%10%15%19%13%4
2292
September1st to 15thDay
38%7%9%21%16%6%
2112
16th to endDay
35%6%8%24%22%3
1790
October1st to 15thDay
36%5%8%23%19%6%
1650
16th to endDay
31%46%26%24%7%
1760
November1st to 15thDay
30%48%27%19%8%
1758
16th to endDay
39%48%18%23%4
1554
December1st to 15thDay
38%5%11%21%17%4
1440
16th to endDay
43%5%8%21%17%3
1635
January1st to 15thNight
36%5%7%23%24%3
2327
16th to endNight
34%39%26%21%4
2496
February1st to 15thNight
38%5%9%24%17%4
2288
16th to endNight
34%6%10%25%16%5%
1874
March1st to 15thNight
43%6%9%17%17%5%
1980
16th to endNight
44%6%9%22%14%2
2112
April1st to 15thNight
33%6%10%24%20%4
1815
16th to endNight
37%6%10%26%16%2
1800
May1st to 15thNight
36%7%15%19%17%3
1683
16th to endNight
35%10%17%21%13%1
1685
June1st to 15thNight
20%7%15%33%21%1
1458
16th to endNight
22%6%16%27%22%4
1526
July1st to 15thNight
29%8%16%26%17%1
1530
16th to endNight
23%8%16%34%15%1
1594
August1st to 15thNight
26%8%16%28%17%1
1613
16th to endNight
29%8%16%24%16%4
1910
September1st to 15thNight
31%5%11%26%16%8%
1767
16th to endNight
31%5%10%21%25%5%
1826
October1st to 15thNight
29%5%13%21%22%8%
1980
16th to endNight
29%36%24%26%8%
2112
November1st to 15thNight
29%310%24%22%8%
2100
16th to endNight
37%5%7%21%23%5%
2400
December1st to 15thNight
39%6%10%21%17%5%
2520
16th to endNight
45%48%19%17%4
2586

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%27%33%17%3
90
16th to endDay
15%41%30%8%4
96
February1st to 15thDay
16%27%46%6%11
90
16th to endDay
22%30%34%7%4
81
March1st to 15thDay
26%26%35%11%
90
16th to endDay
12%32%32%19%3
96
April1st to 15thDay
14%22%33%20%8%
251
16th to endDay
23%18%27%19%8%2
270
May1st to 15thDay
15%17%37%18%9%1
402
16th to endDay
13%10%41%20%10%3
517
June1st to 15thDay
9%425%33%19%6%
495
16th to endDay
6%428%34%20%6%
495
July1st to 15thDay
8%322%35%22%6%
475
16th to endDay
5%7%31%38%16%
515
August1st to 15thDay
11%113%31%34%8%
490
16th to endDay
10%113%30%30%13%
332
September1st to 15thDay
12%6%11%25%32%12%
299
16th to endDay
12%224%24%26%9%
112
October1st to 15thDay
6%11%36%28%14%2
90
16th to endDay
14%7%42%25%8%2
96
November1st to 15thDay
7%12%35%25%13%5%
90
16th to endDay
28%32%21%12%41
90
December1st to 15thDay
15%28%28%18%25%
90
16th to endDay
22%25%35%15%1
96
January1st to 15thNight
19%23%32%19%4
900
16th to endNight
14%23%34%23%4
960
February1st to 15thNight
16%22%36%22%2
880
16th to endNight
16%23%37%20%2
612
March1st to 15thNight
20%17%30%28%3
540
16th to endNight
19%15%33%24%6%
576
April1st to 15thNight
11%23%34%24%6%
539
16th to endNight
15%14%34%26%8%
540
May1st to 15thNight
14%10%33%28%11%1
540
16th to endNight
10%8%29%28%20%2
563
June1st to 15thNight
5%419%37%31%2
540
16th to endNight
4221%35%31%4
540
July1st to 15thNight
5%215%35%36%4
510
16th to endNight
46%30%46%10%
564
August1st to 15thNight
7%7%29%44%9%
539
16th to endNight
4111%36%38%7%
573
September1st to 15thNight
13%213%25%41%3
530
16th to endNight
12%316%31%30%5%
528
October1st to 15thNight
12%7%25%25%24%3
660
16th to endNight
13%13%29%27%14%1
704
November1st to 15thNight
11%17%30%27%13%
700
16th to endNight
18%18%31%23%8%
810
December1st to 15thNight
17%18%34%22%7%
900
16th to endNight
19%21%30%23%4
960
Page generated at 2017-09-13 06:39:21. Version ac04

Copyright 2017 A. Danko


Morgan Point Observatory Clear Sky Chart | Charts Home