Ross River
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ross River clear sky chart from 2005-11-05 to 2017-12-01.

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
46%
14466
5%
47549
4%
14441
47%
14441
12%
37130

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
38%
925
5%
3223
4%
925
39%
925
9%
2618
January16th to endNight
40%
816
9%
3091
8%
816
43%
816
10%
2409
February1st to 15thNight
48%
728
7%
2631
6%
727
50%
727
13%
1946
February16th to endNight
51%
657
7%
2183
6%
657
52%
657
14%
1653
March1st to 15thNight
51%
720
10%
2160
9%
720
52%
720
17%
1609
March16th to endNight
54%
638
7%
2019
7%
638
54%
638
14%
1510
April1st to 15thNight
52%
539
4%
1646
4%
539
52%
539
14%
1253
April16th to endNight
50%
474
0%
1374
0%
474
50%
474
15%
1053
May1st to 15thNight
54%
359
0%
1125
0%
359
54%
359
19%
787
May16th to endNight
64%
326
0%
892
0%
326
64%
326
28%
592
June1st to 15thNight
57%
180
0%
720
0%
180
57%
180
14%
497
June16th to endNight
51%
180
0%
720
0%
180
51%
180
11%
541
July1st to 15thNight
51%
170
0%
680
0%
170
51%
170
12%
510
July16th to endNight
54%
324
0%
926
0%
302
53%
302
14%
692
August1st to 15thNight
58%
367
0%
1132
0%
365
58%
365
18%
816
August16th to endNight
43%
573
0%
1538
0%
573
43%
573
12%
1262
September1st to 15thNight
47%
540
4%
1724
4%
540
48%
540
13%
1319
September16th to endNight
43%
685
6%
1954
5%
685
44%
685
12%
1567
October1st to 15thNight
45%
720
9%
2268
8%
720
46%
720
15%
1685
October16th to endNight
39%
796
4%
2679
3%
796
41%
796
9%
2178
November1st to 15thNight
42%
805
3%
2895
3%
805
43%
805
8%
2400
November16th to endNight
39%
1017
5%
3312
4%
1017
41%
1017
8%
2730
December1st to 15thNight
38%
935
4%
3201
4%
935
39%
935
8%
2683
December16th to endNight
42%
992
6%
3456
5%
992
43%
992
9%
2820

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
9%10%5%10%9%5%7%6%7%7%20%
48965
Night
6%12%6%11%9%5%7%7%7%7%18%
47644
TransparencyDay
57%11%16%11%2
48566
Night
58%9%16%12%2
47549
SeeingDay
14%6%19%26%23%10%
7882
Night
11%313%32%29%9%
14480

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
5%14%6%15%13%6%6%8%8%6%8%
716
16th to endDay
110%7%14%9%6%9%9%9%7%12%
1143
February1st to 15thDay
28%6%9%12%5%11%10%10%10%11%
1233
16th to endDay
28%5%13%13%11%9%7%7%5%15%
1288
March1st to 15thDay
18%7%11%8%5%8%8%10%10%19%
1800
16th to endDay
18%6%11%9%5%7%6%8%9%25%
2205
April1st to 15thDay
410%7%11%9%47%5%7%8%22%
2301
16th to endDay
412%6%11%8%46%6%7%7%24%
2586
May1st to 15thDay
8%13%5%10%8%36%5%5%7%24%
2826
16th to endDay
9%8%47%6%46%5%7%9%29%
3219
June1st to 15thDay
15%9%49%8%47%6%6%7%20%
3240
16th to endDay
14%9%5%10%8%5%7%7%6%7%17%
3240
July1st to 15thDay
16%9%5%8%8%5%7%6%6%7%18%
3240
16th to endDay
12%8%310%8%5%8%6%6%7%20%
3172
August1st to 15thDay
10%7%37%7%5%7%7%7%7%28%
2820
16th to endDay
21%10%49%8%47%6%6%6%14%
2664
September1st to 15thDay
12%11%410%8%47%5%5%6%22%
2235
16th to endDay
12%10%49%9%47%5%5%7%23%
2005
October1st to 15thDay
9%13%49%6%36%6%6%8%24%
1692
16th to endDay
7%13%5%11%10%5%8%7%5%6%17%
1545
November1st to 15thDay
413%8%14%11%8%10%7%5%411%
1281
16th to endDay
413%5%13%16%5%9%8%10%6%6%
975
December1st to 15thDay
5%12%6%13%12%5%7%10%7%6%11%
771
16th to endDay
411%7%13%11%7%9%5%6%10%11%
768
January1st to 15thNight
414%8%13%10%5%7%7%7%7%11%
3223
16th to endNight
312%8%13%11%5%7%7%8%8%14%
3091
February1st to 15thNight
29%6%11%11%6%9%9%9%8%14%
2619
16th to endNight
19%7%11%10%6%9%9%8%7%18%
2183
March1st to 15thNight
19%7%12%9%6%8%7%5%8%24%
2160
16th to endNight
11%6%12%10%47%6%6%7%25%
2014
April1st to 15thNight
39%6%10%10%5%7%7%6%8%24%
1646
16th to endNight
311%7%8%9%5%6%6%6%8%26%
1374
May1st to 15thNight
7%8%5%6%7%46%6%6%8%32%
1124
16th to endNight
8%8%445%3445%11%39%
892
June1st to 15thNight
11%6%37%7%6%6%5%7%8%28%
720
16th to endNight
13%6%211%7%5%6%6%6%10%23%
720
July1st to 15thNight
13%7%48%9%5%7%5%7%9%21%
720
16th to endNight
10%7%38%8%5%8%6%7%8%25%
993
August1st to 15thNight
9%7%47%5%37%7%6%9%29%
1138
16th to endNight
20%9%49%8%4445%5%22%
1538
September1st to 15thNight
13%9%47%9%45%45%7%27%
1724
16th to endNight
12%12%48%7%46%6%5%6%24%
1954
October1st to 15thNight
11%15%38%5%345%5%6%30%
2268
16th to endNight
6%16%7%13%9%45%5%6%6%17%
2679
November1st to 15thNight
414%7%14%11%7%8%7%5%5%11%
2895
16th to endNight
5%15%8%14%11%5%7%8%8%5%9%
3312
December1st to 15thNight
5%15%8%13%11%6%8%7%8%5%9%
3201
16th to endNight
314%6%14%12%7%9%6%7%8%9%
3456

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
65%10%11%8%3
716
16th to endDay
58%10%14%10%5%
1143
February1st to 15thDay
52%10%18%14%4
1233
16th to endDay
60%8%16%11%2
1288
March1st to 15thDay
49%10%14%17%6%1
1800
16th to endDay
50%12%15%16%5%
2205
April1st to 15thDay
56%10%19%12%1
2301
16th to endDay
55%10%19%13%1
2586
May1st to 15thDay
57%8%17%14%2
2826
16th to endDay
46%9%19%18%5%
3224
June1st to 15thDay
59%10%13%13%2
3240
16th to endDay
62%10%13%10%2
3240
July1st to 15thDay
61%12%15%9%1
3051
16th to endDay
59%13%18%7%1
2976
August1st to 15thDay
49%14%19%13%1
2801
16th to endDay
67%11%14%6%
2664
September1st to 15thDay
58%11%16%11%1
2235
16th to endDay
55%13%17%11%2
2005
October1st to 15thDay
53%12%22%11%
1692
16th to endDay
60%10%20%7%
1545
November1st to 15thDay
68%8%14%7%
1281
16th to endDay
65%10%12%10%2
975
December1st to 15thDay
61%10%17%8%1
771
16th to endDay
64%9%13%8%4
768
January1st to 15thNight
63%9%12%10%2
3223
16th to endNight
60%9%13%12%4
3091
February1st to 15thNight
54%8%15%16%4
2631
16th to endNight
55%9%17%13%4
2183
March1st to 15thNight
53%8%13%18%5%1
2160
16th to endNight
54%9%16%15%4
2019
April1st to 15thNight
53%10%18%14%1
1646
16th to endNight
54%10%15%15%3
1374
May1st to 15thNight
46%9%23%17%3
1125
16th to endNight
40%6%21%24%5%
892
June1st to 15thNight
48%10%20%16%4
720
16th to endNight
55%11%17%13%1
720
July1st to 15thNight
54%11%19%13%
680
16th to endNight
51%11%22%13%
926
August1st to 15thNight
49%9%20%18%1
1132
16th to endNight
60%10%16%11%
1538
September1st to 15thNight
55%9%19%14%
1724
16th to endNight
57%12%17%12%1
1954
October1st to 15thNight
52%9%19%16%1
2268
16th to endNight
62%10%16%8%1
2679
November1st to 15thNight
65%10%15%7%
2895
16th to endNight
66%8%13%9%2
3312
December1st to 15thNight
67%9%13%7%1
3201
16th to endNight
65%8%13%9%3
3456

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%20%23%26%20%
30
16th to endDay
6%19%34%31%7%
63
February1st to 15thDay
7%212%39%28%9%
164
16th to endDay
3212%32%29%18%
211
March1st to 15thDay
27%21%24%28%15%
240
16th to endDay
3419%23%31%17%
282
April1st to 15thDay
7%7%23%30%22%9%
308
16th to endDay
9%7%27%29%20%6%
450
May1st to 15thDay
19%8%23%25%15%8%
468
16th to endDay
13%5%18%25%23%12%
700
June1st to 15thDay
17%6%17%28%23%7%
675
16th to endDay
17%5%17%24%24%10%
675
July1st to 15thDay
19%315%24%25%11%
645
16th to endDay
16%6%21%23%23%8%
599
August1st to 15thDay
10%420%29%23%11%
494
16th to endDay
24%7%20%20%21%4
513
September1st to 15thDay
18%15%19%21%15%8%
315
16th to endDay
16%10%27%22%14%8%
313
October1st to 15thDay
17%9%22%26%17%6%
270
16th to endDay
13%312%27%32%9%
216
November1st to 15thDay
11%13%37%21%16%
90
16th to endDay
7%316%22%28%21%
90
December1st to 15thDay
15%5%15%33%30%
39
16th to endDay
9%312%25%34%15%
32
January1st to 15thNight
9%216%34%28%8%
930
16th to endNight
9%219%37%25%5%
816
February1st to 15thNight
5%213%40%30%6%
734
16th to endNight
4112%40%30%10%
657
March1st to 15thNight
4316%34%31%8%
720
16th to endNight
5%110%30%38%13%
639
April1st to 15thNight
6%211%30%38%10%
539
16th to endNight
6%217%32%32%7%
474
May1st to 15thNight
11%6%16%25%33%7%
360
16th to endNight
12%36%25%45%5%
327
June1st to 15thNight
15%17%31%37%6%
180
16th to endNight
16%212%28%34%5%
180
July1st to 15thNight
13%415%22%38%5%
170
16th to endNight
15%214%20%36%11%
324
August1st to 15thNight
11%211%28%36%8%
367
16th to endNight
23%212%24%27%8%
573
September1st to 15thNight
18%5%13%27%26%8%
540
16th to endNight
17%6%17%28%23%6%
685
October1st to 15thNight
17%5%15%35%21%3
720
16th to endNight
14%314%30%28%7%
796
November1st to 15thNight
10%211%36%26%11%
805
16th to endNight
10%412%32%26%14%
1017
December1st to 15thNight
10%412%34%28%9%
935
16th to endNight
7%310%35%29%14%
992
Page generated at 2017-12-02 06:14:23. Version ac04

Copyright 2017 A. Danko


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