Rosetown
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rosetown clear sky chart from 2005-11-05 to 2017-09-23.

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
42%
15537
12%
46836
8%
15511
46%
15511
21%
32326

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
32%
895
8%
2685
4%
895
35%
895
15%
2005
January16th to endNight
28%
960
12%
2841
5%
960
35%
960
15%
2119
February1st to 15thNight
36%
732
9%
2321
7%
732
39%
732
15%
1724
February16th to endNight
44%
632
13%
2052
9%
632
49%
632
17%
1490
March1st to 15thNight
41%
720
13%
2082
9%
720
44%
720
22%
1486
March16th to endNight
38%
723
12%
2067
7%
723
42%
723
16%
1550
April1st to 15thNight
38%
539
14%
1765
9%
539
44%
539
21%
1180
April16th to endNight
40%
540
14%
1548
9%
540
43%
540
21%
1092
May1st to 15thNight
48%
539
11%
1440
7%
539
50%
539
30%
950
May16th to endNight
46%
431
6%
1368
5%
431
48%
431
22%
929
June1st to 15thNight
47%
360
1%
1184
0%
360
47%
360
20%
798
June16th to endNight
54%
360
0%
1158
0%
360
54%
360
25%
733
July1st to 15thNight
64%
340
1%
1190
0%
340
64%
340
30%
675
July16th to endNight
62%
394
11%
1256
9%
371
66%
371
40%
637
August1st to 15thNight
69%
539
15%
1450
11%
536
72%
536
42%
839
August16th to endNight
61%
573
22%
1734
17%
573
65%
573
40%
957
September1st to 15thNight
56%
540
17%
1800
16%
540
59%
540
31%
1037
September16th to endNight
51%
625
25%
1895
19%
625
58%
625
37%
1081
October1st to 15thNight
42%
660
20%
1980
13%
660
49%
660
27%
1289
October16th to endNight
39%
800
16%
2263
8%
800
45%
800
23%
1567
November1st to 15thNight
35%
875
16%
2450
7%
875
41%
875
20%
1747
November16th to endNight
30%
900
12%
2520
5%
900
35%
900
16%
1893
December1st to 15thNight
28%
900
5%
2841
3%
900
31%
900
10%
2309
December16th to endNight
36%
960
11%
2946
6%
960
41%
960
14%
2239

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
11%8%37%6%35%5%5%7%34%
48093
Night
9%8%47%6%35%5%5%8%35%
46987
TransparencyDay
47%7%15%21%7%
47746
Night
45%7%15%21%8%1
46839
SeeingDay
14%7%25%28%18%5%
6181
Night
13%5%27%34%16%2
15552

By Month

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%10%5%12%8%45%5%7%7%23%
1253
16th to endDay
6%12%7%9%7%36%5%6%8%27%
1382
February1st to 15thDay
9%11%6%12%7%6%7%446%23%
1548
16th to endDay
9%13%6%11%9%46%5%6%6%21%
1422
March1st to 15thDay
8%10%6%10%7%5%8%5%6%7%24%
1875
16th to endDay
11%12%5%9%8%35%45%8%24%
2156
April1st to 15thDay
11%9%48%6%45%6%6%7%29%
2180
16th to endDay
15%11%46%6%35%447%30%
2412
May1st to 15thDay
13%6%26%7%45%5%5%7%36%
2511
16th to endDay
18%7%35%6%35%5%5%6%31%
2744
June1st to 15thDay
17%8%36%6%35%5%5%7%31%
2772
16th to endDay
15%5%26%6%45%5%6%7%33%
2797
July1st to 15thDay
8%3245%35%6%6%9%44%
2700
16th to endDay
7%213425%5%6%10%50%
2828
August1st to 15thDay
11%5%34335%46%7%43%
2501
16th to endDay
9%31432445%8%49%
2468
September1st to 15thDay
11%5%25%42335%6%48%
2160
16th to endDay
12%5%1431245%8%50%
1901
October1st to 15thDay
14%8%35%5%24446%39%
1650
16th to endDay
10%9%46%5%35%6%6%8%32%
1595
November1st to 15thDay
9%12%5%7%4336%5%5%36%
1408
16th to endDay
11%11%7%11%8%45%5%46%23%
1440
December1st to 15thDay
10%12%6%11%9%5%6%47%7%16%
1116
16th to endDay
5%12%6%11%9%6%7%6%6%8%19%
1274
January1st to 15thNight
7%10%5%9%7%5%6%6%6%8%26%
2685
16th to endNight
6%10%6%9%6%46%6%7%8%28%
2841
February1st to 15thNight
6%11%6%10%8%46%5%5%7%27%
2313
16th to endNight
6%10%6%9%8%46%5%6%8%27%
2052
March1st to 15thNight
7%10%48%6%36%5%6%9%32%
2082
16th to endNight
10%10%48%7%36%5%6%9%26%
2064
April1st to 15thNight
9%10%36%5%35%46%8%36%
1765
16th to endNight
13%9%36%5%36%5%46%36%
1548
May1st to 15thNight
12%6%25%5%345%6%7%40%
1439
16th to endNight
15%6%25%5%245%6%6%38%
1368
June1st to 15thNight
15%5%34436%6%6%9%33%
1184
16th to endNight
11%5%245%25%5%7%7%41%
1158
July1st to 15thNight
5%314435%5%8%9%48%
1260
16th to endNight
5%11332337%10%57%
1341
August1st to 15thNight
5%2124245%5%9%55%
1458
16th to endNight
7%313323349%55%
1734
September1st to 15thNight
11%4145%24346%50%
1800
16th to endNight
9%42332345%7%54%
1895
October1st to 15thNight
12%8%345%2445%6%41%
1980
16th to endNight
11%9%46%5%25%45%6%37%
2263
November1st to 15thNight
12%9%46%6%2436%7%34%
2450
16th to endNight
7%13%5%11%7%44446%30%
2520
December1st to 15thNight
10%13%5%10%10%5%6%5%6%7%18%
2841
16th to endNight
5%11%5%10%9%5%7%6%5%8%24%
2946

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
57%9%13%14%5%
1253
16th to endDay
52%8%15%16%5%1
1382
February1st to 15thDay
61%6%10%16%4
1548
16th to endDay
60%5%13%12%6%
1422
March1st to 15thDay
55%9%18%14%2
1875
16th to endDay
56%8%14%16%3
2157
April1st to 15thDay
50%8%14%16%8%1
2180
16th to endDay
53%6%13%17%6%1
2412
May1st to 15thDay
45%6%12%26%7%
2511
16th to endDay
50%8%12%17%10%
2749
June1st to 15thDay
50%7%13%21%7%
2772
16th to endDay
47%9%17%20%5%
2797
July1st to 15thDay
34%9%17%30%7%
2541
16th to endDay
28%9%21%31%8%
2650
August1st to 15thDay
37%7%22%23%7%
2485
16th to endDay
30%8%17%31%10%
2468
September1st to 15thDay
36%7%15%24%13%3
2160
16th to endDay
31%6%15%33%11%1
1901
October1st to 15thDay
45%6%16%25%5%
1650
16th to endDay
48%8%17%22%3
1595
November1st to 15thDay
48%6%16%20%6%
1408
16th to endDay
62%7%14%13%2
1440
December1st to 15thDay
64%9%12%11%2
1116
16th to endDay
59%8%15%12%4
1274
January1st to 15thNight
54%7%17%16%4
2685
16th to endNight
52%9%14%16%6%
2841
February1st to 15thNight
54%7%14%17%6%
2324
16th to endNight
53%6%13%18%8%
2052
March1st to 15thNight
47%7%18%19%6%
2082
16th to endNight
52%8%14%17%5%
2067
April1st to 15thNight
44%6%13%21%11%1
1765
16th to endNight
48%6%11%19%11%2
1548
May1st to 15thNight
39%5%11%26%14%
1440
16th to endNight
44%8%13%20%12%1
1368
June1st to 15thNight
43%9%15%22%8%
1184
16th to endNight
36%9%17%26%7%
1158
July1st to 15thNight
27%10%19%32%8%
1190
16th to endNight
22%7%20%37%10%1
1256
August1st to 15thNight
24%8%23%32%9%1
1450
16th to endNight
26%6%14%34%16%1
1734
September1st to 15thNight
34%5%13%25%16%6%
1800
16th to endNight
28%6%11%35%15%2
1895
October1st to 15thNight
41%5%15%25%10%
1980
16th to endNight
46%6%16%23%7%
2263
November1st to 15thNight
48%7%14%20%7%1
2450
16th to endNight
54%7%16%16%4
2520
December1st to 15thNight
63%8%13%12%1
2841
16th to endNight
55%8%15%16%4
2946

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
13%8%21%23%25%8%
60
16th to endDay
16%8%29%25%15%4
71
February1st to 15thDay
14%440%31%6%3
90
16th to endDay
20%235%22%18%
81
March1st to 15thDay
15%9%36%25%9%3
174
16th to endDay
18%10%31%27%11%1
288
April1st to 15thDay
13%15%35%21%10%2
269
16th to endDay
21%9%23%28%15%1
342
May1st to 15thDay
13%8%24%32%15%5%
468
16th to endDay
14%8%21%26%19%8%
517
June1st to 15thDay
16%8%27%25%17%4
495
16th to endDay
16%8%23%28%19%3
495
July1st to 15thDay
8%321%31%26%7%
475
16th to endDay
9%424%30%24%6%
515
August1st to 15thDay
13%316%29%26%10%
474
16th to endDay
9%5%20%38%20%5%
332
September1st to 15thDay
17%7%22%30%17%4
315
16th to endDay
17%5%24%29%19%4
229
October1st to 15thDay
28%231%20%13%4
90
16th to endDay
16%226%29%17%8%
96
November1st to 15thDay
10%5%34%34%14%1
90
16th to endDay
12%13%20%21%20%13%
90
December1st to 15thDay
8%331%32%11%13%
61
16th to endDay
18%339%23%10%4
64
January1st to 15thNight
12%7%33%32%12%1
900
16th to endNight
11%9%37%31%9%
960
February1st to 15thNight
11%5%27%33%17%3
740
16th to endNight
10%325%31%24%4
632
March1st to 15thNight
11%5%29%36%13%2
720
16th to endNight
14%7%26%35%14%2
723
April1st to 15thNight
15%9%28%34%11%1
539
16th to endNight
18%7%27%29%15%1
540
May1st to 15thNight
16%322%36%18%2
540
16th to endNight
16%7%21%31%19%3
432
June1st to 15thNight
16%423%33%19%2
360
16th to endNight
14%5%20%35%23%
360
July1st to 15thNight
6%319%46%22%1
340
16th to endNight
6%224%41%22%1
394
August1st to 15thNight
6%214%38%33%4
539
16th to endNight
8%223%38%26%1
573
September1st to 15thNight
14%220%40%20%2
540
16th to endNight
11%329%34%19%1
625
October1st to 15thNight
16%5%26%34%16%1
660
16th to endNight
15%5%29%33%14%1
800
November1st to 15thNight
16%8%30%32%10%2
875
16th to endNight
13%9%32%32%11%1
900
December1st to 15thNight
16%6%29%28%15%2
900
16th to endNight
11%5%26%33%18%3
960
Page generated at 2017-09-24 07:15:57. Version ac04

Copyright 2017 A. Danko


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