Murray Reservoir
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Murray Reservoir clear sky chart from 2005-11-05 to 2017-12-20.

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
55%
15091
19%
48040
16%
15066
59%
15066
27%
29700

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
43%
716
10%
2506
8%
716
47%
716
13%
1835
January16th to endNight
49%
768
12%
2688
13%
768
51%
768
18%
1832
February1st to 15thNight
43%
697
9%
2283
8%
696
47%
696
15%
1652
February16th to endNight
41%
632
13%
1895
9%
632
47%
632
18%
1371
March1st to 15thNight
46%
720
11%
2160
9%
720
50%
720
17%
1555
March16th to endNight
42%
768
14%
2011
8%
768
45%
768
20%
1449
April1st to 15thNight
44%
719
15%
1799
6%
719
48%
719
26%
1236
April16th to endNight
47%
618
20%
1698
11%
618
52%
618
31%
1055
May1st to 15thNight
47%
446
19%
1526
15%
446
54%
446
30%
833
May16th to endNight
58%
374
15%
1496
20%
374
63%
374
22%
872
June1st to 15thNight
55%
360
13%
1440
16%
360
62%
360
23%
828
June16th to endNight
67%
360
21%
1440
29%
360
75%
360
39%
647
July1st to 15thNight
78%
340
23%
1360
33%
340
85%
340
52%
520
July16th to endNight
78%
376
33%
1416
41%
354
87%
354
60%
501
August1st to 15thNight
81%
405
33%
1477
35%
403
86%
403
51%
616
August16th to endNight
78%
761
36%
1907
23%
761
81%
761
70%
922
September1st to 15thNight
78%
720
37%
1800
21%
720
82%
720
67%
889
September16th to endNight
69%
716
33%
1978
26%
716
72%
716
44%
1088
October1st to 15thNight
60%
720
23%
2090
18%
720
67%
720
37%
1195
October16th to endNight
61%
768
22%
2457
21%
768
66%
768
29%
1478
November1st to 15thNight
51%
760
18%
2470
17%
760
55%
760
21%
1647
November16th to endNight
47%
780
13%
2659
10%
780
53%
780
18%
1794
December1st to 15thNight
49%
780
13%
2730
11%
780
54%
780
18%
1881
December16th to endNight
39%
787
13%
2754
11%
787
44%
787
14%
2004

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
46%36%6%35%5%5%7%44%
48823
Night
46%35%5%35%5%6%7%46%
48209
Cloud CoverDay
5%6%36%5%35%5%5%7%45%
48823
Night
46%35%5%35%5%6%7%46%
48213
TransparencyDay
37%7%11%20%16%7%
48494
Night
35%8%13%22%15%5%
48041
SeeingDay
9%13%28%28%16%3
5727
Night
7%8%21%34%23%5%
15104

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
39%49%9%46%7%8%9%26%
1432
16th to endDay
6%8%47%8%46%6%6%10%28%
1536
February1st to 15thDay
312%410%7%5%6%7%5%8%28%
1580
16th to endDay
29%410%8%5%7%7%7%8%28%
1579
March1st to 15thDay
49%5%10%10%6%8%6%7%7%24%
1800
16th to endDay
411%5%11%8%5%6%7%5%6%26%
2208
April1st to 15thDay
6%8%5%9%8%5%6%6%6%7%29%
2149
16th to endDay
6%7%46%6%35%45%7%42%
2262
May1st to 15thDay
45%37%6%345%6%8%44%
2422
16th to endDay
9%8%48%7%5%6%5%5%7%31%
2615
June1st to 15thDay
8%6%38%7%5%5%5%5%7%38%
2520
16th to endDay
43134245%5%6%57%
2520
July1st to 15thDay
2213325%446%63%
2520
16th to endDay
12212335%75%
2657
August1st to 15thDay
22342345%8%63%
2475
16th to endDay
2212323335%70%
2294
September1st to 15thDay
222212345%71%
2160
16th to endDay
5%5%25%5%23346%54%
1980
October1st to 15thDay
7%6%25%424348%50%
1869
16th to endDay
6%7%36%7%345%48%43%
1767
November1st to 15thDay
7%8%47%7%46%5%5%8%33%
1719
16th to endDay
46%48%8%46%6%7%8%32%
1631
December1st to 15thDay
5%10%5%7%7%5%6%6%7%7%31%
1560
16th to endDay
6%12%5%8%8%47%6%5%7%27%
1568
January1st to 15thNight
310%6%8%6%45%6%6%7%32%
2506
16th to endNight
5%9%47%6%36%6%6%9%35%
2688
February1st to 15thNight
48%38%8%46%5%5%8%33%
2272
16th to endNight
38%38%7%48%6%6%7%33%
1895
March1st to 15thNight
5%7%47%7%36%7%7%9%32%
2160
16th to endNight
35%46%6%5%7%8%8%9%33%
2007
April1st to 15thNight
5%7%36%6%47%5%7%8%39%
1799
16th to endNight
46%35%4345%5%8%48%
1698
May1st to 15thNight
4414435%5%6%7%52%
1526
16th to endNight
45%36%6%36%45%7%45%
1496
June1st to 15thNight
6%5%345%35%46%8%46%
1440
16th to endNight
3213423448%61%
1440
July1st to 15thNight
12222348%71%
1440
16th to endNight
1121223478%
1512
August1st to 15thNight
2122235%5%7%66%
1485
16th to endNight
111213236%75%
1907
September1st to 15thNight
21111223476%
1800
16th to endNight
331442435%6%59%
1978
October1st to 15thNight
442442445%7%54%
2090
16th to endNight
5%5%235%36%5%6%7%47%
2457
November1st to 15thNight
6%6%45%6%36%5%7%8%38%
2470
16th to endNight
47%36%7%46%7%5%7%38%
2659
December1st to 15thNight
5%9%37%6%46%5%7%8%36%
2730
16th to endNight
6%12%48%6%45%5%7%7%30%
2754

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
5%10%6%10%8%46%5%6%9%26%
1432
16th to endDay
7%9%5%10%7%5%6%6%7%7%26%
1536
February1st to 15thDay
5%13%410%6%46%5%6%8%29%
1580
16th to endDay
38%310%6%47%8%8%8%30%
1579
March1st to 15thDay
49%48%8%5%8%7%7%8%26%
1800
16th to endDay
412%5%8%8%5%7%6%6%6%28%
2208
April1st to 15thDay
6%8%49%8%46%6%6%8%31%
2149
16th to endDay
6%8%36%5%36%5%5%7%43%
2262
May1st to 15thDay
5%5%25%6%3446%7%47%
2422
16th to endDay
8%8%37%7%46%5%5%6%35%
2615
June1st to 15thDay
8%6%46%6%36%5%46%40%
2520
16th to endDay
431332445%6%59%
2520
July1st to 15thDay
221331445%6%65%
2520
16th to endDay
11221223476%
2657
August1st to 15thDay
222423348%65%
2475
16th to endDay
2212223345%71%
2294
September1st to 15thDay
2212212335%72%
2160
16th to endDay
5%4245%33446%55%
1980
October1st to 15thDay
6%6%25%5%2445%7%50%
1869
16th to endDay
7%7%36%5%3445%7%44%
1767
November1st to 15thDay
8%9%37%5%45%6%5%8%35%
1719
16th to endDay
6%7%38%6%5%6%6%7%9%31%
1631
December1st to 15thDay
6%10%5%8%6%46%7%6%7%30%
1560
16th to endDay
8%11%49%8%45%5%5%6%27%
1568
January1st to 15thNight
411%6%9%6%46%5%7%7%30%
2506
16th to endNight
5%11%38%7%346%8%8%32%
2688
February1st to 15thNight
49%39%7%46%6%6%7%33%
2272
16th to endNight
47%48%6%47%7%6%9%33%
1895
March1st to 15thNight
48%46%7%37%7%7%9%33%
2160
16th to endNight
36%36%7%47%7%8%10%34%
2011
April1st to 15thNight
5%7%36%5%35%6%6%8%41%
1799
16th to endNight
46%345%1345%8%51%
1698
May1st to 15thNight
442343446%7%54%
1526
16th to endNight
5%5%25%6%36%5%5%8%44%
1496
June1st to 15thNight
7%424425%6%7%7%46%
1440
16th to endNight
321332335%9%61%
1440
July1st to 15thNight
11112225%7%72%
1440
16th to endNight
1221113479%
1512
August1st to 15thNight
21132345%7%67%
1485
16th to endNight
111212336%75%
1907
September1st to 15thNight
11111233477%
1800
16th to endNight
331342345%6%60%
1978
October1st to 15thNight
5%4135%2445%7%55%
2090
16th to endNight
5%5%245%35%5%5%8%47%
2457
November1st to 15thNight
6%6%35%5%36%6%6%9%38%
2470
16th to endNight
5%8%36%6%45%6%6%6%39%
2659
December1st to 15thNight
6%9%37%6%45%5%7%8%34%
2730
16th to endNight
7%13%5%8%6%445%6%7%29%
2754

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
53%12%15%13%4
1432
16th to endDay
51%10%19%13%41
1536
February1st to 15thDay
51%12%14%16%3
1580
16th to endDay
49%13%13%18%31
1579
March1st to 15thDay
54%12%10%16%41
1800
16th to endDay
52%10%14%17%4
2208
April1st to 15thDay
48%7%14%21%6%1
2149
16th to endDay
39%7%13%23%14%1
2262
May1st to 15thDay
33%7%12%31%13%1
2422
16th to endDay
47%8%11%21%9%
2619
June1st to 15thDay
42%6%10%22%14%3
2520
16th to endDay
23%5%7%27%26%8%
2520
July1st to 15thDay
19%48%17%29%21%
2371
16th to endDay
12%25%11%34%34%
2490
August1st to 15thDay
18%36%20%30%19%
2458
16th to endDay
15%36%19%35%18%
2294
September1st to 15thDay
15%36%21%34%18%
2160
16th to endDay
29%5%8%27%21%8%
1980
October1st to 15thDay
33%5%11%25%20%3
1869
16th to endDay
39%6%12%22%17%
1767
November1st to 15thDay
46%9%14%20%8%
1719
16th to endDay
46%9%17%18%7%1
1631
December1st to 15thDay
50%11%14%17%5%
1560
16th to endDay
57%7%13%16%5%
1568
January1st to 15thNight
51%11%15%15%6%
2506
16th to endNight
45%9%15%19%8%1
2688
February1st to 15thNight
47%12%15%16%6%
2283
16th to endNight
45%12%16%17%7%1
1895
March1st to 15thNight
45%11%13%20%6%1
2160
16th to endNight
41%13%15%24%5%
2011
April1st to 15thNight
38%9%15%25%9%
1799
16th to endNight
32%7%16%28%14%
1698
May1st to 15thNight
29%7%13%34%14%
1527
16th to endNight
36%8%13%30%11%
1496
June1st to 15thNight
34%9%13%26%13%2
1440
16th to endNight
21%5%11%32%23%5%
1440
July1st to 15thNight
13%47%25%29%20%
1360
16th to endNight
10%2415%35%30%
1416
August1st to 15thNight
14%47%21%29%21%
1477
16th to endNight
10%26%22%35%21%
1907
September1st to 15thNight
12%35%25%33%20%
1800
16th to endNight
23%5%9%26%23%11%
1978
October1st to 15thNight
28%5%13%25%22%4
2090
16th to endNight
32%8%15%20%21%1
2457
November1st to 15thNight
39%11%13%22%11%1
2470
16th to endNight
43%10%15%17%11%1
2659
December1st to 15thNight
44%11%16%19%7%
2730
16th to endNight
51%9%13%18%7%
2754

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
18%116%23%28%11%
60
16th to endDay
20%6%21%26%20%4
64
February1st to 15thDay
14%11%27%29%13%3
210
16th to endDay
8%17%35%28%9%
238
March1st to 15thDay
11%19%36%26%6%
270
16th to endDay
13%24%35%21%4
288
April1st to 15thDay
14%19%36%15%8%4
269
16th to endDay
11%24%32%17%10%2
270
May1st to 15thDay
13%20%27%25%10%2
288
16th to endDay
17%11%20%29%16%4
330
June1st to 15thDay
9%20%27%24%13%5%
315
16th to endDay
312%30%28%20%3
315
July1st to 15thDay
38%26%35%23%2
305
16th to endDay
27%31%36%17%4
327
August1st to 15thDay
5%325%35%22%7%
315
16th to endDay
37%21%30%25%10%
332
September1st to 15thDay
5%6%22%34%23%7%
315
16th to endDay
8%9%26%31%22%1
315
October1st to 15thDay
11%15%29%23%17%1
315
16th to endDay
12%13%21%30%16%5%
183
November1st to 15thDay
11%14%27%34%12%
135
16th to endDay
15%15%31%26%12%
106
December1st to 15thDay
13%15%25%23%6%15%
90
16th to endDay
9%16%23%29%19%1
72
January1st to 15thNight
10%10%21%32%19%5%
720
16th to endNight
12%8%15%32%24%6%
768
February1st to 15thNight
9%8%24%31%20%4
704
16th to endNight
8%10%28%31%18%3
632
March1st to 15thNight
7%10%24%34%18%3
720
16th to endNight
7%16%28%32%13%1
768
April1st to 15thNight
8%12%27%29%19%2
719
16th to endNight
7%12%26%28%19%4
618
May1st to 15thNight
7%11%27%29%19%4
447
16th to endNight
6%6%20%37%24%4
375
June1st to 15thNight
7%7%24%34%24%1
360
16th to endNight
3420%42%25%2
360
July1st to 15thNight
2115%50%27%3
340
16th to endNight
115%54%25%2
376
August1st to 15thNight
2111%44%34%5%
405
16th to endNight
1114%38%37%6%
761
September1st to 15thNight
2214%32%37%10%
720
16th to endNight
6%5%13%33%30%10%
716
October1st to 15thNight
8%6%19%34%22%8%
720
16th to endNight
9%7%15%36%23%8%
768
November1st to 15thNight
10%8%22%34%21%1
760
16th to endNight
9%12%23%28%19%6%
780
December1st to 15thNight
12%6%23%31%21%5%
780
16th to endNight
14%11%23%33%14%2
787
Page generated at 2017-12-21 04:04:50. Version ac04

Copyright 2017 A. Danko


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