Paul Plishner Radio Astronomy and Science Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Paul Plishner Radio Astronomy and Science Center clear sky chart from 2005-11-05 to 2018-01-12.

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
54%
16406
28%
48331
19%
16362
62%
16362
42%
26214

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
59%
956
28%
2662
21%
951
65%
951
47%
1415
January16th to endNight
56%
855
34%
2583
23%
855
65%
855
47%
1304
February1st to 15thNight
48%
703
24%
2131
17%
700
55%
700
36%
1209
February16th to endNight
45%
632
33%
1894
18%
632
58%
632
44%
996
March1st to 15thNight
49%
720
28%
2160
16%
720
58%
720
42%
1158
March16th to endNight
41%
621
28%
2009
16%
621
54%
621
37%
1040
April1st to 15thNight
32%
539
25%
1798
14%
539
49%
539
35%
943
April16th to endNight
39%
540
23%
1793
16%
540
53%
540
33%
979
May1st to 15thNight
42%
540
22%
1620
16%
540
53%
540
31%
956
May16th to endNight
41%
561
18%
1584
10%
561
51%
561
32%
984
June1st to 15thNight
48%
540
22%
1440
11%
540
55%
540
45%
806
June16th to endNight
55%
540
24%
1440
13%
540
62%
540
47%
817
July1st to 15thNight
67%
510
18%
1360
15%
510
68%
510
35%
857
July16th to endNight
71%
564
21%
1416
18%
531
72%
531
39%
864
August1st to 15thNight
62%
539
15%
1748
15%
536
64%
536
28%
1065
August16th to endNight
71%
573
26%
1910
29%
573
75%
573
38%
1009
September1st to 15thNight
61%
540
26%
1813
25%
540
68%
540
38%
954
September16th to endNight
61%
537
36%
1980
32%
537
72%
537
43%
904
October1st to 15thNight
52%
603
31%
2043
22%
603
61%
603
39%
1026
October16th to endNight
65%
853
38%
2389
24%
853
70%
853
54%
1194
November1st to 15thNight
61%
950
35%
2470
19%
950
67%
950
57%
1277
November16th to endNight
60%
975
38%
2535
22%
975
67%
975
53%
1344
December1st to 15thNight
53%
975
28%
2641
16%
975
60%
975
45%
1470
December16th to endNight
51%
1040
31%
2912
18%
1040
60%
1040
40%
1643

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%31332345%7%58%
49022
Night
5%41332445%7%57%
48504
Cloud CoverDay
5%31332345%7%58%
49020
Night
5%41432445%7%57%
48504
TransparencyDay
23%411%25%24%10%
48697
Night
25%411%24%23%9%
48332
SeeingDay
7%5%22%32%24%6%
6174
Night
7%5%28%41%16%1
16409

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
4324213237%63%
1520
16th to endDay
442322335%5%62%
1653
February1st to 15thDay
45%35%43435%6%54%
1729
16th to endDay
25%15%42345%5%58%
1580
March1st to 15thDay
3313423448%61%
1800
16th to endDay
7%5%2331445%7%53%
2213
April1st to 15thDay
7%5%2432335%7%54%
2150
16th to endDay
8%5%1442345%7%50%
2166
May1st to 15thDay
9%4133245%5%8%51%
2331
16th to endDay
5%31232445%8%57%
2528
June1st to 15thDay
42123235%6%10%57%
2520
16th to endDay
211131345%8%65%
2520
July1st to 15thDay
4212325%5%7%11%53%
2520
16th to endDay
5%11222447%10%56%
2656
August1st to 15thDay
5%2134246%7%10%51%
2198
16th to endDay
5%21331345%10%58%
2292
September1st to 15thDay
6%31332446%7%57%
2145
16th to endDay
5%212223446%65%
1980
October1st to 15thDay
6%21321325%6%62%
1915
16th to endDay
432312245%69%
1821
November1st to 15thDay
3323212345%66%
1718
16th to endDay
4212221236%68%
1755
December1st to 15thDay
36%24423336%59%
1648
16th to endDay
6%6%2432235%7%53%
1664
January1st to 15thNight
3414324345%61%
2662
16th to endNight
3423312337%63%
2583
February1st to 15thNight
5%5%35%423347%52%
2121
16th to endNight
342432345%6%57%
1894
March1st to 15thNight
441332445%6%57%
2160
16th to endNight
7%5%23323347%57%
2009
April1st to 15thNight
7%414323447%56%
1798
16th to endNight
10%41432336%6%52%
1793
May1st to 15thNight
10%4144235%5%7%50%
1619
16th to endNight
8%423425%6%5%8%48%
1583
June1st to 15thNight
3212335%6%7%9%54%
1440
16th to endNight
3313325%5%7%9%55%
1440
July1st to 15thNight
43145%37%6%7%10%43%
1440
16th to endNight
4224436%5%6%8%50%
1512
August1st to 15thNight
6%325%6%47%6%7%8%42%
1757
16th to endNight
5%1134346%7%9%53%
1910
September1st to 15thNight
7%31343445%9%52%
1813
16th to endNight
4213322347%63%
1980
October1st to 15thNight
8%313323345%60%
2043
16th to endNight
4312213335%68%
2389
November1st to 15thNight
3212223346%66%
2470
16th to endNight
4312312345%67%
2535
December1st to 15thNight
3415%42345%6%57%
2641
16th to endNight
5%6%24323345%57%
2912

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
4324313236%63%
1520
16th to endDay
442321335%5%62%
1653
February1st to 15thDay
45%25%434346%54%
1729
16th to endDay
25%25%423445%58%
1580
March1st to 15thDay
2313423448%61%
1800
16th to endDay
7%5%2332445%7%53%
2211
April1st to 15thDay
7%42432335%7%54%
2150
16th to endDay
8%5%2443345%7%50%
2166
May1st to 15thDay
9%4133245%5%8%51%
2331
16th to endDay
5%31332346%8%57%
2528
June1st to 15thDay
42123235%6%11%57%
2520
16th to endDay
211131345%9%65%
2520
July1st to 15thDay
4213425%5%7%11%53%
2520
16th to endDay
42122245%7%9%56%
2656
August1st to 15thDay
5%2134245%7%10%51%
2198
16th to endDay
5%21232345%9%58%
2292
September1st to 15thDay
6%2133245%5%7%57%
2145
16th to endDay
4212213446%65%
1980
October1st to 15thDay
6%31231325%6%62%
1915
16th to endDay
432212245%69%
1821
November1st to 15thDay
3313213345%66%
1718
16th to endDay
3313211336%68%
1755
December1st to 15thDay
36%24423336%59%
1648
16th to endDay
6%6%2432235%8%53%
1664
January1st to 15thNight
3414324345%61%
2662
16th to endNight
3423312337%63%
2583
February1st to 15thNight
5%5%25%5%23347%52%
2121
16th to endNight
242441345%7%57%
1894
March1st to 15thNight
45%2332445%6%58%
2160
16th to endNight
7%5%23323347%57%
2009
April1st to 15thNight
7%323324448%55%
1798
16th to endNight
10%42431435%7%52%
1793
May1st to 15thNight
10%4244235%47%50%
1619
16th to endNight
8%323425%6%6%7%48%
1583
June1st to 15thNight
3213335%6%6%9%54%
1440
16th to endNight
3313315%5%6%8%55%
1440
July1st to 15thNight
43145%37%7%7%10%43%
1440
16th to endNight
4324335%6%6%8%50%
1512
August1st to 15thNight
6%325%6%46%6%7%8%42%
1757
16th to endNight
5%2133346%7%9%53%
1910
September1st to 15thNight
7%313424449%52%
1813
16th to endNight
4213313347%63%
1980
October1st to 15thNight
8%313323346%59%
2043
16th to endNight
4312213245%68%
2389
November1st to 15thNight
3212223346%66%
2470
16th to endNight
4313212345%67%
2535
December1st to 15thNight
35%25%42345%6%57%
2641
16th to endNight
5%5%24324346%57%
2912

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
23%39%29%27%6%
1521
16th to endDay
23%39%30%25%7%
1653
February1st to 15thDay
30%49%30%18%6%
1730
16th to endDay
26%210%22%27%10%
1580
March1st to 15thDay
20%410%25%26%11%
1800
16th to endDay
28%412%23%23%7%
2213
April1st to 15thDay
28%310%25%21%10%
2150
16th to endDay
31%412%23%19%8%
2166
May1st to 15thDay
28%5%12%28%19%5%
2331
16th to endDay
22%5%15%27%18%9%
2532
June1st to 15thDay
19%5%14%25%22%12%
2520
16th to endDay
15%311%25%26%17%
2520
July1st to 15thDay
22%7%11%21%26%10%
2371
16th to endDay
20%7%15%26%24%6%
2489
August1st to 15thDay
23%8%17%25%15%9%
2183
16th to endDay
21%6%9%28%25%8%
2292
September1st to 15thDay
24%412%23%22%11%
2145
16th to endDay
18%47%23%32%12%
1980
October1st to 15thDay
22%310%20%31%11%
1915
16th to endDay
18%27%26%32%13%
1821
November1st to 15thDay
19%39%24%28%14%
1718
16th to endDay
18%16%23%33%15%
1755
December1st to 15thDay
27%310%27%26%5%
1648
16th to endDay
29%312%27%21%5%
1664
January1st to 15thNight
23%310%28%27%6%
2662
16th to endNight
22%38%30%27%7%
2583
February1st to 15thNight
31%311%27%20%4
2131
16th to endNight
24%39%25%26%10%
1894
March1st to 15thNight
26%48%22%29%9%
2160
16th to endNight
26%412%22%22%11%
2009
April1st to 15thNight
26%49%26%22%9%
1798
16th to endNight
29%5%14%23%20%6%
1793
May1st to 15thNight
32%6%13%20%19%7%
1620
16th to endNight
31%8%16%18%14%10%
1585
June1st to 15thNight
22%7%18%24%17%9%
1440
16th to endNight
23%6%12%22%20%14%
1440
July1st to 15thNight
31%9%14%22%14%7%
1360
16th to endNight
29%7%17%21%19%4
1416
August1st to 15thNight
34%9%17%20%11%6%
1748
16th to endNight
25%7%12%26%20%7%
1910
September1st to 15thNight
27%414%25%18%10%
1813
16th to endNight
20%47%22%32%11%
1980
October1st to 15thNight
25%411%18%27%12%
2043
16th to endNight
18%37%23%29%17%
2389
November1st to 15thNight
18%28%23%27%18%
2470
16th to endNight
20%26%23%29%16%
2535
December1st to 15thNight
26%311%29%23%6%
2641
16th to endNight
28%311%26%24%4
2912

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
10%420%39%20%4
123
16th to endDay
14%326%30%22%3
96
February1st to 15thDay
6%338%36%14%
90
16th to endDay
1435%38%17%2
81
March1st to 15thDay
5%5%27%42%15%3
90
16th to endDay
17%10%26%29%11%4
242
April1st to 15thDay
10%15%37%22%10%3
269
16th to endDay
15%15%29%31%7%
276
May1st to 15thDay
10%10%27%29%17%3
468
16th to endDay
9%7%29%30%19%3
517
June1st to 15thDay
5%5%25%31%24%8%
495
16th to endDay
3320%34%31%6%
495
July1st to 15thDay
5%15%31%35%11%
475
16th to endDay
6%9%31%38%13%
515
August1st to 15thDay
4116%38%31%7%
347
16th to endDay
5%18%37%29%8%
332
September1st to 15thDay
3124%34%22%13%
300
16th to endDay
12%16%29%26%14%
135
October1st to 15thDay
7%418%28%30%10%
135
16th to endDay
6%425%20%29%13%
144
November1st to 15thDay
4217%37%26%12%
135
16th to endDay
10%12%21%30%25%
135
December1st to 15thDay
5%7%28%40%16%1
135
16th to endDay
6%5%26%44%15%1
144
January1st to 15thNight
5%325%45%17%2
956
16th to endNight
6%427%47%13%
855
February1st to 15thNight
7%432%45%9%
704
16th to endNight
5%6%39%39%9%
632
March1st to 15thNight
7%435%38%12%1
720
16th to endNight
9%9%36%35%8%
621
April1st to 15thNight
10%10%44%27%5%
539
16th to endNight
13%9%35%32%8%
540
May1st to 15thNight
14%7%31%33%12%
540
16th to endNight
9%6%37%34%10%
563
June1st to 15thNight
4439%41%10%
540
16th to endNight
5%231%47%12%
540
July1st to 15thNight
5%17%51%23%
510
16th to endNight
5%13%46%31%2
564
August1st to 15thNight
6%119%40%30%1
539
16th to endNight
5%116%47%27%2
573
September1st to 15thNight
10%120%42%23%1
540
16th to endNight
4227%42%21%1
537
October1st to 15thNight
10%7%26%35%17%1
603
16th to endNight
6%5%21%40%23%2
853
November1st to 15thNight
5%325%42%22%1
950
16th to endNight
6%5%22%43%19%1
975
December1st to 15thNight
6%5%29%45%12%
975
16th to endNight
7%8%27%41%15%
1040
Page generated at 2018-01-12 20:01:25. Version ac04

Copyright 2018 A. Danko


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