Franklin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Franklin clear sky chart from 2005-11-05 to 2017-03-24.

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
48%
14919
23%
45135
17%
14875
54%
14875
29%
27845

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
28%
900
21%
2506
10%
895
37%
895
23%
1692
January16th to endNight
27%
774
22%
2379
11%
774
38%
774
21%
1594
February1st to 15thNight
26%
704
18%
2112
9%
701
35%
701
22%
1434
February16th to endNight
26%
631
21%
1893
10%
631
36%
631
21%
1281
March1st to 15thNight
30%
720
19%
2160
10%
720
37%
720
22%
1450
March16th to endNight
38%
671
19%
1968
13%
671
43%
671
26%
1272
April1st to 15thNight
41%
494
27%
1647
18%
494
54%
494
31%
931
April16th to endNight
46%
495
25%
1634
17%
495
56%
495
32%
922
May1st to 15thNight
47%
494
22%
1485
14%
494
54%
494
28%
951
May16th to endNight
64%
513
19%
1539
15%
513
67%
513
34%
913
June1st to 15thNight
70%
495
22%
1427
17%
495
73%
495
39%
828
June16th to endNight
78%
495
24%
1320
18%
495
80%
495
48%
742
July1st to 15thNight
71%
465
19%
1240
16%
465
73%
465
38%
759
July16th to endNight
77%
522
20%
1445
19%
489
79%
489
38%
835
August1st to 15thNight
79%
494
23%
1606
25%
491
81%
491
38%
875
August16th to endNight
75%
525
21%
1750
26%
525
75%
525
33%
1010
September1st to 15thNight
66%
553
24%
1708
24%
553
68%
553
30%
1047
September16th to endNight
65%
657
30%
1815
24%
657
67%
657
38%
1077
October1st to 15thNight
56%
660
35%
1815
27%
660
62%
660
39%
1052
October16th to endNight
50%
704
31%
2189
25%
704
58%
704
33%
1263
November1st to 15thNight
49%
700
31%
2276
26%
700
58%
700
34%
1260
November16th to endNight
41%
720
27%
2340
21%
720
51%
720
29%
1380
December1st to 15thNight
33%
720
21%
2340
15%
720
42%
720
21%
1538
December16th to endNight
30%
813
20%
2541
12%
813
39%
813
20%
1739

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%6%25%5%35%5%5%7%39%
45791
Night
12%5%2442445%7%44%
45322
TransparencyDay
41%410%22%16%3
45481
Night
38%410%23%19%4
45136
SeeingDay
14%417%23%24%16%
4815
Night
15%6%22%30%21%3
14922

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
18%7%25%5%24445%37%
1432
16th to endDay
17%6%35%433335%41%
1840
February1st to 15thDay
16%9%37%5%33345%36%
1750
16th to endDay
15%8%37%5%35%45%6%35%
1580
March1st to 15thDay
18%8%37%5%33345%36%
1800
16th to endDay
14%7%36%5%36%45%6%34%
2109
April1st to 15thDay
11%6%245%34446%44%
1971
16th to endDay
12%5%35%6%3445%6%41%
1994
May1st to 15thDay
17%6%26%5%3445%6%37%
2136
16th to endDay
9%6%27%5%36%5%5%8%38%
2223
June1st to 15thDay
7%425%6%35%6%7%8%42%
2199
16th to endDay
4325%6%46%7%7%10%40%
2310
July1st to 15thDay
9%435%7%47%7%7%9%32%
2310
16th to endDay
6%326%6%5%8%8%8%10%32%
2305
August1st to 15thDay
5%325%7%47%6%8%11%37%
2010
16th to endDay
9%5%26%6%46%6%6%9%34%
2100
September1st to 15thDay
11%5%25%7%46%6%6%8%34%
1911
16th to endDay
11%5%145%24447%48%
1815
October1st to 15thDay
12%5%24323246%51%
1815
16th to endDay
15%423323435%53%
1682
November1st to 15thDay
14%5%12323246%53%
1582
16th to endDay
15%5%2421435%6%48%
1620
December1st to 15thDay
20%9%36%42335%5%35%
1620
16th to endDay
19%9%25%6%23335%37%
1677
January1st to 15thNight
16%9%35%5%23345%39%
2506
16th to endNight
16%8%35%424445%39%
2379
February1st to 15thNight
17%8%35%5%23335%38%
2103
16th to endNight
16%7%36%5%2445%5%37%
1893
March1st to 15thNight
16%6%36%5%34446%38%
2160
16th to endNight
14%7%35%42445%7%40%
1968
April1st to 15thNight
12%424423448%49%
1647
16th to endNight
11%42443445%7%48%
1634
May1st to 15thNight
10%6%26%5%35%45%6%42%
1484
16th to endNight
6%425%5%245%6%9%46%
1538
June1st to 15thNight
5%4135%25%5%6%11%48%
1427
16th to endNight
2213435%49%12%52%
1320
July1st to 15thNight
9%325%335%5%6%12%42%
1320
16th to endNight
42135%36%6%8%12%44%
1552
August1st to 15thNight
3314435%5%6%12%49%
1617
16th to endNight
6%325%5%25%6%6%11%43%
1750
September1st to 15thNight
9%4246%35%6%5%7%44%
1708
16th to endNight
10%32442335%6%52%
1815
October1st to 15thNight
10%6%23323346%53%
1815
16th to endNight
14%5%24312345%52%
2189
November1st to 15thNight
11%5%24323346%53%
2276
16th to endNight
15%6%24322346%48%
2340
December1st to 15thNight
17%9%345%2435%5%38%
2340
16th to endNight
20%8%36%43433436%
2541

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
48%26%22%16%2
1433
16th to endDay
45%28%26%14%1
1840
February1st to 15thDay
49%28%21%14%3
1752
16th to endDay
48%39%22%13%2
1580
March1st to 15thDay
50%39%19%14%4
1800
16th to endDay
48%411%21%12%
2110
April1st to 15thDay
39%410%22%19%4
1971
16th to endDay
41%47%24%18%3
1994
May1st to 15thDay
45%411%22%14%2
2136
16th to endDay
42%5%13%24%11%2
2227
June1st to 15thDay
36%5%13%27%16%1
2199
16th to endDay
34%7%12%22%17%4
2310
July1st to 15thDay
42%6%17%19%10%4
2161
16th to endDay
38%8%19%22%9%1
2149
August1st to 15thDay
36%5%15%23%15%3
1997
16th to endDay
42%6%12%22%13%3
2100
September1st to 15thDay
44%6%11%19%14%4
1911
16th to endDay
34%310%23%24%3
1815
October1st to 15thDay
34%37%23%25%5%
1815
16th to endDay
34%35%22%28%6%
1682
November1st to 15thDay
33%25%22%27%7%
1582
16th to endDay
37%26%29%19%4
1620
December1st to 15thDay
50%27%21%14%3
1620
16th to endDay
49%311%20%12%2
1677
January1st to 15thNight
46%37%21%17%2
2506
16th to endNight
48%36%21%16%3
2379
February1st to 15thNight
49%29%21%15%2
2112
16th to endNight
48%38%21%15%2
1893
March1st to 15thNight
45%48%18%17%5%
2160
16th to endNight
42%412%25%14%1
1968
April1st to 15thNight
33%411%23%21%5%
1647
16th to endNight
34%39%25%23%4
1634
May1st to 15thNight
40%5%11%24%16%2
1485
16th to endNight
32%6%18%25%14%3
1540
June1st to 15thNight
28%6%17%28%16%1
1427
16th to endNight
22%7%17%32%15%5%
1320
July1st to 15thNight
31%6%17%25%14%4
1240
16th to endNight
27%7%20%28%14%2
1445
August1st to 15thNight
25%7%16%28%18%2
1606
16th to endNight
32%6%15%24%17%3
1750
September1st to 15thNight
36%5%13%21%17%4
1708
16th to endNight
32%48%21%26%7%
1815
October1st to 15thNight
31%37%22%28%7%
1815
16th to endNight
34%3321%28%8%
2189
November1st to 15thNight
32%2421%27%10%
2276
16th to endNight
37%27%23%23%4
2340
December1st to 15thNight
47%38%20%16%4
2340
16th to endNight
51%28%19%16%2
2541

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
25%13%37%11%11%1
90
16th to endDay
19%9%47%18%4
96
February1st to 15thDay
22%12%43%15%5%1
90
16th to endDay
23%9%40%17%7%1
81
March1st to 15thDay
26%13%35%21%3
90
16th to endDay
15%7%29%31%13%1
257
April1st to 15thDay
13%10%28%27%17%2
210
16th to endDay
16%422%28%22%5%
210
May1st to 15thDay
18%7%23%23%20%7%
228
16th to endDay
15%28%28%25%17%
267
June1st to 15thDay
10%13%18%28%28%
309
16th to endDay
5%110%29%29%23%
420
July1st to 15thDay
10%112%30%29%16%
400
16th to endDay
7%1417%25%43%
291
August1st to 15thDay
6%318%36%34%
253
16th to endDay
15%116%38%26%
268
September1st to 15thDay
13%17%18%33%25%
255
16th to endDay
17%27%25%34%12%
254
October1st to 15thDay
15%120%26%26%10%
255
16th to endDay
22%117%32%19%7%
125
November1st to 15thDay
13%5%22%30%23%5%
90
16th to endDay
18%12%33%18%15%1
90
December1st to 15thDay
21%11%38%20%6%2
90
16th to endDay
17%14%42%18%6%
96
January1st to 15thNight
23%12%30%26%5%
900
16th to endNight
22%9%36%28%3
774
February1st to 15thNight
20%11%35%27%4
704
16th to endNight
21%13%34%28%3
631
March1st to 15thNight
19%10%34%28%6%
720
16th to endNight
17%8%28%29%14%1
671
April1st to 15thNight
13%10%32%30%10%2
494
16th to endNight
12%6%30%37%12%1
495
May1st to 15thNight
13%327%34%18%2
495
16th to endNight
7%313%35%33%6%
515
June1st to 15thNight
7%111%38%34%7%
495
16th to endNight
29%31%46%8%
495
July1st to 15thNight
8%16%34%39%8%
465
16th to endNight
45%23%50%14%
522
August1st to 15thNight
3426%53%11%
494
16th to endNight
8%433%43%10%
525
September1st to 15thNight
10%29%28%43%6%
553
16th to endNight
12%211%29%40%3
657
October1st to 15thNight
13%318%30%26%7%
660
16th to endNight
16%5%22%32%20%2
704
November1st to 15thNight
13%6%25%30%19%4
700
16th to endNight
19%8%26%31%12%1
720
December1st to 15thNight
22%9%27%29%9%1
720
16th to endNight
24%8%31%28%6%
813
Page generated at 2017-03-25 11:39:45. Version ac04

Copyright 2017 A. Danko


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