Whitefish
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Whitefish clear sky chart from 2005-11-05 to 2017-09-20.

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
27%
15268
14%
46800
7%
15227
35%
15227
17%
32477

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
18%
899
9%
2643
4%
895
23%
895
11%
2047
January16th to endNight
22%
894
13%
2622
5%
894
30%
894
12%
1994
February1st to 15thNight
18%
702
12%
2287
5%
701
27%
701
12%
1677
February16th to endNight
21%
631
13%
1973
5%
631
29%
631
12%
1465
March1st to 15thNight
21%
720
14%
2046
5%
720
29%
720
17%
1431
March16th to endNight
27%
768
20%
2112
9%
768
37%
768
22%
1387
April1st to 15thNight
26%
626
18%
1773
8%
626
33%
626
20%
1229
April16th to endNight
26%
540
18%
1620
6%
540
36%
540
17%
1088
May1st to 15thNight
32%
514
15%
1594
8%
514
39%
514
17%
1063
May16th to endNight
31%
375
15%
1428
8%
374
45%
374
19%
846
June1st to 15thNight
30%
360
12%
1260
7%
360
39%
360
18%
789
June16th to endNight
39%
360
11%
1260
9%
360
45%
360
21%
758
July1st to 15thNight
46%
340
16%
1190
14%
340
52%
340
30%
650
July16th to endNight
41%
503
15%
1404
11%
471
50%
471
29%
864
August1st to 15thNight
48%
539
17%
1609
13%
536
54%
536
30%
968
August16th to endNight
47%
573
20%
1719
11%
573
55%
573
29%
1048
September1st to 15thNight
42%
690
18%
1857
9%
690
47%
690
31%
1158
September16th to endNight
41%
677
20%
1870
12%
677
47%
677
29%
1197
October1st to 15thNight
30%
660
18%
1955
11%
660
39%
660
20%
1348
October16th to endNight
21%
704
13%
2193
7%
704
30%
704
13%
1627
November1st to 15thNight
26%
700
15%
2372
11%
700
34%
700
15%
1641
November16th to endNight
20%
720
11%
2520
6%
720
27%
720
10%
1896
December1st to 15thNight
14%
813
8%
2613
3%
813
20%
813
9%
2016
December16th to endNight
15%
960
10%
2880
3%
960
22%
960
8%
2290

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
16%9%36%5%3445%6%34%
48039
Night
17%9%36%5%34446%33%
46963
Cloud CoverDay
16%9%36%5%3445%6%34%
48049
Night
16%9%36%5%34446%33%
46967
TransparencyDay
48%412%22%11%1
47721
Night
51%312%21%10%1
46800
SeeingDay
17%18%27%21%9%3
5909
Night
18%22%24%23%9%1
15271

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
19%15%7%8%424345%23%
1292
16th to endDay
16%17%7%8%6%235%4422%
1599
February1st to 15thDay
11%15%6%9%7%435%46%25%
1575
16th to endDay
13%17%5%9%6%3432427%
1497
March1st to 15thDay
16%10%35%5%24445%36%
1903
16th to endDay
13%8%36%5%24345%41%
2112
April1st to 15thDay
21%10%36%433345%33%
2184
16th to endDay
19%8%24323346%40%
2340
May1st to 15thDay
18%7%35%5%3345%6%36%
2355
16th to endDay
15%5%24435%45%8%40%
2684
June1st to 15thDay
15%6%35%5%35%45%8%35%
2700
16th to endDay
16%5%35%6%35%5%6%7%35%
2700
July1st to 15thDay
11%5%245%35%46%8%42%
2700
16th to endDay
10%425%5%35%5%6%9%40%
2661
August1st to 15thDay
14%6%244345%5%8%40%
2340
16th to endDay
13%5%25%5%35%45%8%39%
2483
September1st to 15thDay
13%6%35%5%3445%7%40%
2090
16th to endDay
18%5%244245%46%39%
1859
October1st to 15thDay
20%7%25%5%34446%35%
1675
16th to endDay
28%9%37%5%2445%5%23%
1678
November1st to 15thDay
19%11%35%43435%7%30%
1484
16th to endDay
23%17%6%7%5%3333421%
1440
December1st to 15thDay
17%19%6%8%5%3433422%
1344
16th to endDay
22%16%6%9%5%3344419%
1344
January1st to 15thNight
19%15%49%6%33346%23%
2643
16th to endNight
15%14%5%7%6%35%445%24%
2622
February1st to 15thNight
12%14%5%10%6%35%45%6%25%
2285
16th to endNight
14%13%5%8%6%345%46%25%
1973
March1st to 15thNight
16%10%46%6%34346%34%
2034
16th to endNight
14%7%25%5%34335%43%
2112
April1st to 15thNight
19%9%35%333445%36%
1773
16th to endNight
18%7%26%5%24336%38%
1620
May1st to 15thNight
14%8%26%5%25%5%5%7%36%
1594
16th to endNight
11%5%35%5%25%448%41%
1426
June1st to 15thNight
14%435%436%6%6%6%37%
1260
16th to endNight
10%5%35%445%45%9%40%
1260
July1st to 15thNight
10%415%42346%8%48%
1260
16th to endNight
9%3245%345%48%46%
1502
August1st to 15thNight
11%5%14334447%48%
1620
16th to endNight
12%425%42435%8%46%
1719
September1st to 15thNight
13%5%1442445%7%45%
1857
16th to endNight
14%7%25%423346%45%
1870
October1st to 15thNight
22%7%25%432435%38%
1955
16th to endNight
26%8%36%43445%428%
2193
November1st to 15thNight
19%10%35%5%25%35%6%31%
2372
16th to endNight
23%14%46%424345%25%
2520
December1st to 15thNight
20%15%6%7%5%25%345%23%
2613
16th to endNight
23%14%6%8%5%34335%20%
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
19%15%8%8%433346%22%
1292
16th to endDay
16%16%6%9%6%2445%5%22%
1599
February1st to 15thDay
11%14%5%9%8%45%45%425%
1575
16th to endDay
13%16%410%7%2443427%
1497
March1st to 15thDay
16%10%35%5%24445%35%
1914
16th to endDay
13%7%36%6%2435%5%40%
2111
April1st to 15thDay
20%9%36%5%33335%33%
2184
16th to endDay
19%8%24313346%40%
2340
May1st to 15thDay
18%8%35%42345%6%36%
2355
16th to endDay
14%5%235%25%45%8%40%
2684
June1st to 15thDay
15%6%36%5%3446%8%36%
2700
16th to endDay
14%5%26%5%35%46%8%35%
2700
July1st to 15thDay
10%5%25%4345%6%8%42%
2700
16th to endDay
9%425%5%345%7%8%42%
2661
August1st to 15thDay
13%5%25%4245%5%8%41%
2340
16th to endDay
12%6%25%5%345%6%8%39%
2483
September1st to 15thDay
12%6%25%5%3445%7%41%
2090
16th to endDay
17%6%245%3445%6%39%
1859
October1st to 15thDay
18%8%26%5%25%45%6%34%
1675
16th to endDay
28%9%36%5%2435%5%23%
1678
November1st to 15thDay
19%11%36%5%24448%30%
1484
16th to endDay
23%16%5%7%6%44335%20%
1440
December1st to 15thDay
17%18%7%8%6%3433421%
1344
16th to endDay
20%17%5%9%6%3344419%
1344
January1st to 15thNight
19%15%5%9%6%33446%22%
2643
16th to endNight
16%14%5%7%7%35%5%5%6%24%
2622
February1st to 15thNight
12%14%5%9%6%35%5%5%6%25%
2278
16th to endNight
14%13%5%8%6%35%5%5%6%25%
1973
March1st to 15thNight
16%10%46%6%33345%34%
2046
16th to endNight
14%6%26%5%34345%43%
2112
April1st to 15thNight
19%9%34423445%36%
1773
16th to endNight
19%7%25%5%23346%38%
1620
May1st to 15thNight
14%8%26%435%5%5%7%35%
1593
16th to endNight
12%435%5%3446%8%41%
1426
June1st to 15thNight
13%6%35%5%35%6%6%7%37%
1260
16th to endNight
10%5%35%5%35%5%6%9%39%
1260
July1st to 15thNight
10%42442346%7%49%
1260
16th to endNight
9%4236%35%46%8%46%
1502
August1st to 15thNight
11%5%24424447%48%
1620
16th to endNight
11%5%25%5%3435%7%46%
1719
September1st to 15thNight
13%5%134245%5%6%46%
1857
16th to endNight
14%6%25%422347%44%
1870
October1st to 15thNight
21%6%35%433445%37%
1955
16th to endNight
26%9%26%5%34445%27%
2193
November1st to 15thNight
19%9%45%5%345%5%7%30%
2372
16th to endNight
23%14%47%434445%24%
2520
December1st to 15thNight
20%15%6%8%5%24446%21%
2613
16th to endNight
22%15%5%8%6%34445%20%
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
63%212%15%4
1293
16th to endDay
62%38%15%8%1
1599
February1st to 15thDay
58%413%15%7%
1577
16th to endDay
60%37%19%9%
1497
March1st to 15thDay
49%313%19%14%
1914
16th to endDay
44%310%25%11%4
2112
April1st to 15thDay
53%29%20%12%1
2184
16th to endDay
44%39%24%15%3
2340
May1st to 15thDay
48%310%20%14%3
2355
16th to endDay
40%413%23%16%1
2688
June1st to 15thDay
44%411%24%13%1
2700
16th to endDay
44%5%12%24%12%1
2700
July1st to 15thDay
36%412%29%16%1
2541
16th to endDay
37%6%12%29%13%
2497
August1st to 15thDay
38%5%16%25%12%1
2327
16th to endDay
40%5%16%28%8%
2483
September1st to 15thDay
41%5%15%27%10%
2090
16th to endDay
44%316%27%7%
1859
October1st to 15thDay
49%410%23%11%
1675
16th to endDay
61%314%12%7%
1678
November1st to 15thDay
52%413%22%7%
1484
16th to endDay
67%39%14%5%
1440
December1st to 15thDay
66%210%14%5%
1344
16th to endDay
66%310%15%3
1344
January1st to 15thNight
62%311%16%6%
2643
16th to endNight
60%38%18%8%
2622
February1st to 15thNight
58%312%17%7%
2287
16th to endNight
58%411%17%8%
1973
March1st to 15thNight
51%213%20%10%1
2046
16th to endNight
43%211%20%18%4
2112
April1st to 15thNight
49%27%23%14%1
1773
16th to endNight
48%18%21%16%2
1620
May1st to 15thNight
46%49%23%14%2
1594
16th to endNight
40%411%25%15%2
1428
June1st to 15thNight
43%411%24%14%1
1260
16th to endNight
39%415%24%13%1
1260
July1st to 15thNight
32%313%32%17%1
1190
16th to endNight
36%414%26%16%
1404
August1st to 15thNight
36%316%29%12%1
1609
16th to endNight
36%416%29%11%1
1719
September1st to 15thNight
35%416%30%9%1
1857
16th to endNight
39%314%33%8%
1870
October1st to 15thNight
49%312%23%11%
1955
16th to endNight
58%311%18%7%
2193
November1st to 15thNight
52%314%20%8%
2372
16th to endNight
61%313%15%5%
2520
December1st to 15thNight
64%213%15%3
2613
16th to endNight
66%210%14%5%
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
25%11%43%14%21
67
16th to endDay
33%8%17%30%10%
96
February1st to 15thDay
27%18%34%17%1
90
16th to endDay
29%17%37%16%
81
March1st to 15thDay
20%22%25%21%8%
204
16th to endDay
19%21%26%20%9%2
288
April1st to 15thDay
21%21%22%21%11%1
270
16th to endDay
25%23%25%11%10%3
270
May1st to 15thDay
19%21%23%19%8%6%
288
16th to endDay
15%21%32%20%7%2
397
June1st to 15thDay
16%26%31%18%5%1
495
16th to endDay
16%22%27%20%9%2
495
July1st to 15thDay
11%18%30%27%8%3
475
16th to endDay
9%19%30%25%10%4
461
August1st to 15thDay
15%9%19%31%14%9%
313
16th to endDay
16%11%26%19%15%9%
332
September1st to 15thDay
12%9%22%28%15%10%
315
16th to endDay
20%14%22%24%11%7%
270
October1st to 15thDay
17%17%30%24%9%
255
16th to endDay
25%22%27%17%5%1
190
November1st to 15thDay
19%12%32%28%6%
73
16th to endDay
28%15%36%15%31
60
December1st to 15thDay
26%15%43%10%5%
60
16th to endDay
37%23%34%31
64
January1st to 15thNight
20%27%24%20%5%1
900
16th to endNight
18%24%22%25%8%
894
February1st to 15thNight
17%26%27%22%5%
704
16th to endNight
19%24%24%22%8%
631
March1st to 15thNight
17%27%26%22%5%
720
16th to endNight
16%23%27%22%9%1
768
April1st to 15thNight
18%24%28%21%6%
626
16th to endNight
20%24%22%20%10%
540
May1st to 15thNight
16%23%20%26%12%1
514
16th to endNight
13%22%28%26%8%
375
June1st to 15thNight
15%21%28%30%5%
360
16th to endNight
11%20%20%32%14%1
360
July1st to 15thNight
10%13%23%38%13%
340
16th to endNight
9%19%22%31%15%1
503
August1st to 15thNight
12%12%17%33%20%3
539
16th to endNight
11%12%20%30%22%2
573
September1st to 15thNight
14%13%24%24%17%4
690
16th to endNight
15%13%24%25%17%3
677
October1st to 15thNight
22%15%25%24%10%1
660
16th to endNight
28%19%24%20%41
704
November1st to 15thNight
19%25%23%21%9%
700
16th to endNight
24%27%20%19%7%
720
December1st to 15thNight
23%29%27%15%4
813
16th to endNight
27%27%18%18%6%1
960
Page generated at 2017-09-21 07:18:17. Version ac04

Copyright 2017 A. Danko


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