Elko Observing site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Elko Observing site clear sky chart from 2005-11-05 to 2018-04-23.

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
52%
16438
24%
49529
17%
16397
60%
16397
30%
30081

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
31%
777
23%
2522
12%
776
46%
776
25%
1513
January16th to endNight
34%
832
26%
2639
15%
832
47%
832
26%
1614
February1st to 15thNight
34%
764
25%
2288
13%
760
48%
760
28%
1412
February16th to endNight
34%
683
27%
2049
13%
683
47%
683
30%
1232
March1st to 15thNight
38%
780
29%
2206
14%
780
50%
780
34%
1297
March16th to endNight
41%
832
23%
2288
12%
832
49%
832
32%
1386
April1st to 15thNight
49%
751
26%
2114
19%
751
55%
751
37%
1243
April16th to endNight
55%
558
31%
1758
20%
558
66%
558
38%
952
May1st to 15thNight
57%
539
25%
1620
17%
539
64%
539
35%
938
May16th to endNight
67%
561
22%
1682
17%
561
70%
561
35%
985
June1st to 15thNight
67%
540
16%
1620
14%
540
68%
540
27%
1058
June16th to endNight
72%
540
17%
1620
15%
540
73%
540
29%
1007
July1st to 15thNight
75%
510
11%
1530
9%
510
75%
510
26%
1011
July16th to endNight
72%
564
14%
1595
14%
531
73%
531
27%
1054
August1st to 15thNight
74%
539
16%
1646
17%
536
74%
536
28%
1052
August16th to endNight
66%
591
17%
1928
18%
591
67%
591
22%
1295
September1st to 15thNight
68%
720
18%
1980
16%
720
68%
720
28%
1321
September16th to endNight
61%
717
23%
1980
19%
717
64%
717
28%
1310
October1st to 15thNight
58%
720
31%
1994
25%
720
64%
720
38%
1184
October16th to endNight
59%
768
36%
2304
30%
768
68%
768
41%
1233
November1st to 15thNight
57%
760
30%
2392
26%
760
65%
760
38%
1288
November16th to endNight
46%
780
29%
2535
22%
780
58%
780
32%
1430
December1st to 15thNight
43%
780
25%
2535
18%
780
54%
780
28%
1505
December16th to endNight
39%
832
23%
2704
18%
832
47%
832
22%
1761

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%5%25%5%35%45%7%42%
49977
Night
10%5%2442445%8%45%
49732
TransparencyDay
39%411%19%18%6%
49678
Night
36%411%18%20%8%
49535
SeeingDay
13%6%17%23%23%15%
6203
Night
13%5%20%31%24%4
16444

By Month

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
14%5%24424435%47%
1746
16th to endDay
14%5%24423346%45%
1935
February1st to 15thDay
14%5%35%5%24446%43%
1900
16th to endDay
14%5%2441445%7%45%
1710
March1st to 15thDay
12%5%25%423346%49%
2083
16th to endDay
13%424424446%46%
2287
April1st to 15thDay
11%5%25%43335%5%49%
2174
16th to endDay
8%41432435%7%53%
2313
May1st to 15thDay
8%424425%45%7%48%
2331
16th to endDay
6%426%5%35%6%7%9%42%
2431
June1st to 15thDay
9%5%25%7%47%5%7%10%32%
2340
16th to endDay
5%326%6%47%6%9%11%38%
2340
July1st to 15thDay
8%5%37%7%5%8%8%8%9%27%
2340
16th to endDay
7%436%7%5%9%8%7%10%28%
2465
August1st to 15thDay
10%5%36%7%5%6%6%9%12%26%
2300
16th to endDay
13%7%36%7%47%6%6%9%28%
2262
September1st to 15thDay
11%425%5%35%5%7%9%38%
1980
16th to endDay
14%6%26%5%4445%6%38%
1980
October1st to 15thDay
13%5%23324346%51%
1965
16th to endDay
10%313313335%59%
1920
November1st to 15thDay
10%423423445%55%
1793
16th to endDay
13%425%423435%51%
1755
December1st to 15thDay
16%5%24324346%45%
1755
16th to endDay
20%8%345%33345%37%
1872
January1st to 15thNight
13%7%24423346%47%
2522
16th to endNight
17%5%25%41333447%
2639
February1st to 15thNight
16%5%24423346%46%
2283
16th to endNight
12%424434446%48%
2049
March1st to 15thNight
9%424424348%51%
2206
16th to endNight
11%5%24423346%50%
2288
April1st to 15thNight
11%42342435%7%51%
2114
16th to endNight
7%31342445%9%53%
1758
May1st to 15thNight
6%4344245%6%7%51%
1619
16th to endNight
6%4245%245%6%9%46%
1682
June1st to 15thNight
8%5%26%5%45%7%7%11%35%
1620
16th to endNight
3336%5%47%7%8%11%37%
1620
July1st to 15thNight
5%5%25%5%47%7%9%12%32%
1620
16th to endNight
6%425%7%37%8%9%12%32%
1703
August1st to 15thNight
6%5%25%5%36%6%8%14%35%
1657
16th to endNight
10%5%25%7%46%6%7%10%32%
1928
September1st to 15thNight
10%5%26%436%5%7%9%39%
1980
16th to endNight
9%7%26%6%345%6%7%39%
1980
October1st to 15thNight
12%414423346%53%
1994
16th to endNight
9%413212436%58%
2304
November1st to 15thNight
9%423322346%57%
2392
16th to endNight
11%434323235%53%
2535
December1st to 15thNight
13%425%424446%47%
2535
16th to endNight
17%7%25%5%2445%7%37%
2704

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
39%27%16%25%7%
1747
16th to endDay
40%16%17%23%11%
1935
February1st to 15thDay
43%26%17%21%9%
1902
16th to endDay
38%45%18%25%8%
1710
March1st to 15thDay
37%28%19%20%11%
2083
16th to endDay
38%311%17%23%6%
2288
April1st to 15thDay
36%38%21%21%9%
2174
16th to endDay
29%38%25%23%9%
2313
May1st to 15thDay
34%412%21%21%5%
2331
16th to endDay
35%5%13%26%15%2
2435
June1st to 15thDay
43%6%15%21%11%1
2340
16th to endDay
36%6%18%21%15%2
2340
July1st to 15thDay
46%7%21%16%6%2
2201
16th to endDay
44%8%18%20%7%
2310
August1st to 15thDay
45%7%20%17%7%
2287
16th to endDay
50%6%15%16%10%1
2262
September1st to 15thDay
40%6%14%18%16%3
1980
16th to endDay
45%49%18%16%4
1980
October1st to 15thDay
34%28%20%22%9%
1965
16th to endDay
27%25%15%30%18%
1920
November1st to 15thDay
30%27%19%24%15%
1793
16th to endDay
36%26%14%25%13%
1755
December1st to 15thDay
40%111%16%20%9%
1755
16th to endDay
50%26%19%14%6%
1872
January1st to 15thNight
39%26%17%26%7%
2522
16th to endNight
41%1414%26%11%
2639
February1st to 15thNight
39%2417%22%12%
2292
16th to endNight
37%25%18%22%13%
2049
March1st to 15thNight
32%38%20%23%12%
2206
16th to endNight
35%210%18%22%9%
2288
April1st to 15thNight
33%27%22%22%11%
2114
16th to endNight
28%410%22%21%12%
1758
May1st to 15thNight
31%5%11%20%23%7%
1620
16th to endNight
32%5%15%25%15%5%
1684
June1st to 15thNight
39%8%16%24%11%
1620
16th to endNight
36%7%19%19%13%3
1620
July1st to 15thNight
37%10%25%17%6%2
1530
16th to endNight
37%10%22%19%8%1
1595
August1st to 15thNight
36%9%23%21%8%
1646
16th to endNight
43%9%18%16%11%1
1928
September1st to 15thNight
39%8%14%17%16%3
1980
16th to endNight
42%412%16%18%4
1980
October1st to 15thNight
32%38%22%21%12%
1994
16th to endNight
27%26%15%29%17%
2304
November1st to 15thNight
29%27%16%29%15%
2392
16th to endNight
34%25%17%24%15%
2535
December1st to 15thNight
38%39%18%22%8%
2535
16th to endNight
46%26%20%15%7%
2704

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
12%14%47%16%5%3
135
16th to endDay
13%24%38%13%9%
144
February1st to 15thDay
18%22%34%20%4
135
16th to endDay
15%10%40%28%5%
120
March1st to 15thDay
14%15%30%28%10%1
268
16th to endDay
14%7%32%29%15%
352
April1st to 15thDay
14%12%22%30%16%3
330
16th to endDay
8%323%29%25%8%
289
May1st to 15thDay
9%8%19%24%23%13%
288
16th to endDay
8%310%22%32%23%
331
June1st to 15thDay
12%25%20%25%32%
315
16th to endDay
7%6%21%29%34%
315
July1st to 15thDay
8%5%17%32%36%
305
16th to endDay
7%314%34%38%
326
August1st to 15thDay
17%219%34%25%
313
16th to endDay
14%15%16%36%25%
332
September1st to 15thDay
16%19%21%27%22%
315
16th to endDay
18%16%29%28%14%
314
October1st to 15thDay
18%217%28%21%11%
315
16th to endDay
8%6%21%27%28%6%
336
November1st to 15thDay
17%424%27%25%1
211
16th to endDay
5%11%27%31%22%1
135
December1st to 15thDay
20%12%33%25%5%2
135
16th to endDay
31%13%22%24%6%1
144
January1st to 15thNight
17%12%32%27%9%
780
16th to endNight
19%10%30%31%8%
832
February1st to 15thNight
18%9%31%32%7%
764
16th to endNight
15%8%37%32%4
683
March1st to 15thNight
12%10%34%33%9%
780
16th to endNight
14%10%28%31%14%
832
April1st to 15thNight
14%6%26%33%18%
751
16th to endNight
8%426%35%22%2
558
May1st to 15thNight
8%322%35%25%4
540
16th to endNight
9%112%37%33%6%
563
June1st to 15thNight
10%17%34%37%8%
540
16th to endNight
5%2430%45%11%
540
July1st to 15thNight
7%1428%39%19%
510
16th to endNight
8%1324%50%11%
564
August1st to 15thNight
9%225%50%12%
539
16th to endNight
13%2422%41%16%
591
September1st to 15thNight
13%1428%42%10%
720
16th to endNight
13%19%36%34%3
717
October1st to 15thNight
14%118%32%27%5%
720
16th to endNight
11%5%20%33%27%3
768
November1st to 15thNight
12%419%38%23%2
760
16th to endNight
14%7%27%29%19%1
780
December1st to 15thNight
14%6%29%30%17%1
780
16th to endNight
21%8%25%34%10%1
832
Page generated at 2018-04-24 10:03:03. Version ac04

Copyright 2018 A. Danko


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