Elbow Valley
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Elbow Valley clear sky chart from 2005-11-05 to

2017-09-12
.

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%
15143
14%
46738
9%
15111
47%
15111
24%
30451

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
33%
900
13%
2685
7%
895
38%
895
18%
1882
January16th to endNight
34%
810
19%
2730
12%
810
45%
810
21%
1729
February1st to 15thNight
39%
700
14%
2422
10%
697
47%
697
20%
1545
February16th to endNight
36%
632
15%
1968
11%
632
43%
632
22%
1334
March1st to 15thNight
33%
720
14%
2123
7%
720
41%
720
23%
1435
March16th to endNight
31%
768
12%
2082
4%
768
37%
768
20%
1507
April1st to 15thNight
33%
632
11%
1712
4%
632
37%
632
19%
1236
April16th to endNight
35%
540
12%
1620
9%
540
38%
540
20%
1133
May1st to 15thNight
42%
413
10%
1419
9%
413
47%
413
22%
896
May16th to endNight
44%
374
5%
1309
4%
374
45%
374
17%
915
June1st to 15thNight
43%
360
0%
1260
0%
360
43%
360
17%
887
June16th to endNight
54%
360
1%
1260
0%
360
54%
360
26%
769
July1st to 15thNight
64%
340
2%
1190
0%
340
65%
340
29%
679
July16th to endNight
63%
376
10%
1288
11%
354
66%
354
32%
691
August1st to 15thNight
67%
393
12%
1465
17%
391
69%
391
29%
808
August16th to endNight
64%
573
21%
1719
18%
573
68%
573
42%
912
September1st to 15thNight
56%
658
18%
1777
12%
658
58%
658
39%
1051
September16th to endNight
54%
656
20%
1815
13%
656
60%
656
39%
1067
October1st to 15thNight
43%
660
17%
1946
10%
660
50%
660
23%
1329
October16th to endNight
45%
704
20%
2288
13%
704
55%
704
26%
1416
November1st to 15thNight
36%
814
18%
2389
10%
814
45%
814
26%
1526
November16th to endNight
33%
900
15%
2691
6%
900
41%
900
22%
1792
December1st to 15thNight
38%
900
14%
2700
8%
900
42%
900
18%
1924
December16th to endNight
37%
960
16%
2880
9%
960
44%
960
20%
1988

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
10%8%36%6%35%5%6%8%35%
47955
Night
7%8%36%5%35%5%6%8%38%
46889
Cloud CoverDay
10%8%36%5%35%5%6%8%35%
47956
Night
8%8%36%5%35%5%6%8%37%
46892
TransparencyDay
45%6%16%21%8%1
47610
Night
42%6%16%22%9%1
46738
SeeingDay
15%9%27%28%14%4
5986
Night
11%6%28%35%15%2
15149

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
49%47%5%35%5%6%8%38%
1253
16th to endDay
410%5%7%7%35%46%9%36%
1504
February1st to 15thDay
48%39%5%37%6%6%8%35%
1440
16th to endDay
210%6%9%6%5%6%5%6%7%31%
1503
March1st to 15thDay
38%5%8%9%36%6%6%9%33%
1836
16th to endDay
7%13%6%9%7%45%6%6%7%23%
2141
April1st to 15thDay
12%15%5%8%5%245%5%8%25%
2235
16th to endDay
13%12%47%6%445%6%7%28%
2340
May1st to 15thDay
11%9%36%6%35%5%6%6%32%
2531
16th to endDay
23%8%36%6%45%46%7%23%
2802
June1st to 15thDay
21%8%37%6%36%6%6%6%24%
2700
16th to endDay
15%5%35%6%36%6%7%8%32%
2700
July1st to 15thDay
11%5%24435%6%6%10%39%
2700
16th to endDay
6%414426%6%6%9%45%
2790
August1st to 15thDay
12%5%24435%6%6%8%39%
2486
16th to endDay
9%41442445%9%49%
2483
September1st to 15thDay
12%424423445%50%
2101
16th to endDay
10%5%25%425%35%8%45%
1815
October1st to 15thDay
12%10%46%6%35%5%47%33%
1683
16th to endDay
7%9%35%5%35%5%6%9%38%
1584
November1st to 15thDay
6%10%36%6%45%5%5%7%37%
1458
16th to endDay
411%6%6%6%2445%7%41%
1266
December1st to 15thDay
38%5%10%9%47%7%6%7%29%
1260
16th to endDay
310%5%6%5%45%6%8%10%33%
1344
January1st to 15thNight
410%48%8%5%5%5%7%8%30%
2685
16th to endNight
49%47%6%245%7%9%37%
2730
February1st to 15thNight
49%47%6%36%5%7%9%36%
2411
16th to endNight
49%6%9%7%35%5%5%7%35%
1968
March1st to 15thNight
38%48%7%36%6%7%10%32%
2123
16th to endNight
5%11%6%8%7%35%6%6%7%30%
2079
April1st to 15thNight
10%14%46%435%5%5%7%30%
1712
16th to endNight
12%12%47%5%3435%8%33%
1620
May1st to 15thNight
11%8%35%5%25%45%8%37%
1418
16th to endNight
20%7%36%43446%7%30%
1309
June1st to 15thNight
17%8%35%6%36%45%6%31%
1260
16th to endNight
11%4144346%6%10%40%
1260
July1st to 15thNight
6%4145%35%6%7%9%46%
1260
16th to endNight
5%415%3245%5%8%52%
1376
August1st to 15thNight
10%4133335%7%9%46%
1473
16th to endNight
8%32222346%8%56%
1719
September1st to 15thNight
11%6%1332235%7%52%
1777
16th to endNight
10%5%1232445%8%51%
1815
October1st to 15thNight
12%9%25%6%35%5%5%6%37%
1946
16th to endNight
7%9%25%4345%6%9%42%
2288
November1st to 15thNight
410%35%435%5%6%7%43%
2389
16th to endNight
49%5%8%6%35%45%9%36%
2691
December1st to 15thNight
310%5%8%8%47%6%6%8%30%
2700
16th to endNight
39%49%8%46%5%7%7%32%
2880

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
6%9%47%5%35%5%6%8%37%
1253
16th to endDay
5%10%48%6%4446%8%35%
1504
February1st to 15thDay
410%5%7%6%37%6%6%7%34%
1440
16th to endDay
310%6%10%7%5%6%5%6%8%29%
1503
March1st to 15thDay
39%49%8%36%5%7%7%33%
1836
16th to endDay
7%15%6%9%6%36%6%6%7%24%
2142
April1st to 15thDay
12%15%6%7%5%35%46%7%25%
2235
16th to endDay
13%12%37%6%35%46%7%28%
2340
May1st to 15thDay
11%9%35%6%35%5%6%7%33%
2531
16th to endDay
23%8%37%5%35%5%6%7%24%
2802
June1st to 15thDay
21%8%35%5%45%5%5%7%25%
2700
16th to endDay
15%5%26%5%35%5%7%8%33%
2700
July1st to 15thDay
11%424425%6%7%9%40%
2700
16th to endDay
6%413435%6%7%8%46%
2790
August1st to 15thDay
13%5%244245%7%9%39%
2486
16th to endDay
9%3144245%5%8%50%
2483
September1st to 15thDay
12%5%24323345%50%
2101
16th to endDay
9%7%25%42445%8%44%
1815
October1st to 15thDay
13%9%46%5%345%5%7%33%
1683
16th to endDay
7%9%45%5%345%6%9%38%
1584
November1st to 15thDay
7%11%36%6%35%5%7%6%36%
1458
16th to endDay
6%12%47%5%2345%8%39%
1266
December1st to 15thDay
39%411%7%5%8%6%5%8%28%
1260
16th to endDay
311%47%6%35%6%7%10%32%
1344
January1st to 15thNight
5%10%5%7%8%46%6%5%8%29%
2685
16th to endNight
410%48%5%25%5%7%9%36%
2730
February1st to 15thNight
5%9%47%5%45%5%6%8%36%
2411
16th to endNight
410%6%10%7%45%5%5%6%34%
1968
March1st to 15thNight
38%5%8%8%46%5%6%10%32%
2123
16th to endNight
6%12%5%8%6%35%5%6%8%29%
2082
April1st to 15thNight
12%12%5%7%5%35%5%47%29%
1712
16th to endNight
13%11%48%5%245%48%32%
1620
May1st to 15thNight
11%9%36%5%2445%8%37%
1418
16th to endNight
20%7%26%5%35%45%8%30%
1309
June1st to 15thNight
18%7%45%5%35%45%7%31%
1260
16th to endNight
12%5%24435%5%7%9%39%
1260
July1st to 15thNight
7%315%435%5%5%10%47%
1260
16th to endNight
6%4243245%6%8%51%
1376
August1st to 15thNight
10%3144235%7%10%45%
1473
16th to endNight
7%42221345%9%56%
1719
September1st to 15thNight
12%5%1331235%7%51%
1777
16th to endNight
10%41331336%8%51%
1815
October1st to 15thNight
12%8%26%5%35%5%5%7%37%
1946
16th to endNight
7%9%345%345%6%8%41%
2288
November1st to 15thNight
5%10%35%425%47%7%42%
2389
16th to endNight
5%10%5%7%6%4445%8%36%
2691
December1st to 15thNight
310%6%10%7%47%6%5%7%30%
2700
16th to endNight
310%410%8%36%5%7%7%31%
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
42%6%16%26%6%2
1253
16th to endDay
44%5%16%19%11%3
1504
February1st to 15thDay
43%7%18%21%7%2
1440
16th to endDay
49%6%16%18%8%
1503
March1st to 15thDay
46%6%20%19%7%
1836
16th to endDay
56%8%13%16%5%
2142
April1st to 15thDay
55%6%14%15%6%
2235
16th to endDay
53%5%14%17%7%1
2340
May1st to 15thDay
48%5%15%21%9%
2531
16th to endDay
57%7%13%16%4
2807
June1st to 15thDay
56%6%14%15%5%1
2700
16th to endDay
44%8%18%20%6%1
2700
July1st to 15thDay
38%9%20%23%7%1
2541
16th to endDay
32%8%19%28%10%
2615
August1st to 15thDay
38%8%22%22%6%1
2469
16th to endDay
30%6%19%31%10%1
2483
September1st to 15thDay
35%415%24%17%2
2101
16th to endDay
36%7%13%29%10%2
1815
October1st to 15thDay
48%6%13%20%9%
1683
16th to endDay
40%8%15%26%8%1
1584
November1st to 15thDay
43%6%16%23%8%1
1458
16th to endDay
41%5%18%23%9%2
1266
December1st to 15thDay
50%6%17%16%8%
1260
16th to endDay
42%5%18%21%9%2
1344
January1st to 15thNight
48%6%16%19%6%2
2685
16th to endNight
41%6%15%21%12%3
2730
February1st to 15thNight
42%6%15%23%10%1
2422
16th to endNight
47%413%20%12%
1968
March1st to 15thNight
43%7%20%22%5%
2123
16th to endNight
49%7%15%18%8%
2082
April1st to 15thNight
52%415%17%9%
1712
16th to endNight
49%5%14%22%6%1
1620
May1st to 15thNight
43%416%24%9%
1419
16th to endNight
52%5%17%18%41
1309
June1st to 15thNight
51%6%16%16%8%
1260
16th to endNight
37%6%20%25%8%
1260
July1st to 15thNight
31%7%21%28%9%
1190
16th to endNight
28%7%18%31%11%1
1288
August1st to 15thNight
30%7%23%29%8%
1465
16th to endNight
23%6%19%32%15%2
1719
September1st to 15thNight
31%319%23%18%3
1777
16th to endNight
30%5%19%27%13%4
1815
October1st to 15thNight
45%6%13%21%10%1
1946
16th to endNight
37%6%17%27%10%
2288
November1st to 15thNight
38%6%16%24%13%
2389
16th to endNight
44%5%18%18%9%3
2691
December1st to 15thNight
50%6%15%20%6%
2700
16th to endNight
47%5%14%22%8%
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
11%5%18%26%20%18%
60
16th to endDay
9%6%10%45%17%10%
64
February1st to 15thDay
7%13%28%37%8%4
67
16th to endDay
10%8%22%45%12%1
162
March1st to 15thDay
6%17%49%22%4
270
16th to endDay
12%21%34%21%7%1
288
April1st to 15thDay
23%15%34%20%5%
269
16th to endDay
22%15%29%22%8%1
270
May1st to 15thDay
17%9%32%22%14%4
363
16th to endDay
24%7%17%27%18%3
517
June1st to 15thDay
23%7%25%27%12%3
495
16th to endDay
16%6%29%28%15%4
495
July1st to 15thDay
14%421%27%26%5%
475
16th to endDay
8%6%29%33%17%4
459
August1st to 15thDay
17%324%32%16%5%
315
16th to endDay
10%7%28%34%12%6%
332
September1st to 15thDay
16%7%27%29%14%5%
300
16th to endDay
12%14%27%31%12%1
255
October1st to 15thDay
17%8%30%31%9%2
159
16th to endDay
13%420%34%19%7%
96
November1st to 15thDay
17%7%26%38%6%2
90
16th to endDay
6%13%21%21%21%16%
61
December1st to 15thDay
16%23%41%21%5%
60
16th to endDay
9%10%20%31%23%4
64
January1st to 15thNight
10%12%32%33%9%2
900
16th to endNight
9%11%34%34%9%1
810
February1st to 15thNight
9%10%28%32%14%4
704
16th to endNight
8%434%32%17%3
632
March1st to 15thNight
6%6%41%32%9%3
720
16th to endNight
10%6%35%34%11%1
768
April1st to 15thNight
16%8%29%30%12%1
632
16th to endNight
20%5%27%33%12%
540
May1st to 15thNight
15%5%27%34%16%
414
16th to endNight
24%417%34%18%
375
June1st to 15thNight
22%5%22%32%16%1
360
16th to endNight
13%121%36%25%1
360
July1st to 15thNight
9%213%43%27%3
340
16th to endNight
7%317%46%23%2
376
August1st to 15thNight
11%210%37%32%4
393
16th to endNight
8%318%41%26%2
573
September1st to 15thNight
16%219%31%26%4
658
16th to endNight
12%422%37%17%4
656
October1st to 15thNight
16%6%24%32%16%3
660
16th to endNight
12%428%39%13%1
704
November1st to 15thNight
10%9%36%34%6%1
814
16th to endNight
9%8%37%32%9%1
900
December1st to 15thNight
7%8%32%35%13%2
900
16th to endNight
6%7%33%38%12%2
960
Page generated at 2017-09-13 05:39:07. Version ac04

Copyright 2017 A. Danko


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