Elkford
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Elkford clear sky chart from 2005-11-05 to 2017-10-31.

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
33%
15312
10%
47332
7%
15279
37%
15279
18%
33091

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
17%
891
7%
2676
3%
886
20%
886
9%
2180
January16th to endNight
22%
768
11%
2688
7%
768
28%
768
13%
1958
February1st to 15thNight
23%
702
9%
2422
5%
698
29%
698
13%
1786
February16th to endNight
28%
632
10%
1938
6%
632
33%
632
16%
1425
March1st to 15thNight
22%
720
6%
2133
3%
720
26%
720
13%
1625
March16th to endNight
28%
768
7%
2067
3%
768
31%
768
15%
1596
April1st to 15thNight
33%
655
7%
1735
2%
655
36%
655
18%
1293
April16th to endNight
33%
540
10%
1620
8%
540
35%
540
18%
1139
May1st to 15thNight
44%
419
9%
1472
11%
419
45%
419
21%
924
May16th to endNight
45%
374
5%
1309
5%
374
47%
374
16%
927
June1st to 15thNight
40%
360
2%
1260
0%
360
41%
360
18%
866
June16th to endNight
46%
360
3%
1260
0%
360
47%
360
20%
776
July1st to 15thNight
61%
340
6%
1190
2%
340
63%
340
35%
613
July16th to endNight
64%
376
14%
1342
16%
354
71%
354
34%
662
August1st to 15thNight
66%
396
18%
1468
21%
394
71%
394
32%
764
August16th to endNight
56%
573
24%
1719
20%
573
60%
573
40%
901
September1st to 15thNight
54%
702
19%
1836
11%
702
57%
702
40%
1079
September16th to endNight
46%
716
17%
1980
10%
716
52%
716
30%
1245
October1st to 15thNight
38%
720
14%
2112
8%
720
44%
720
20%
1451
October16th to endNight
34%
768
14%
2496
9%
768
42%
768
18%
1707
November1st to 15thNight
21%
772
10%
2347
5%
772
27%
772
13%
1723
November16th to endNight
22%
900
9%
2682
4%
900
27%
900
14%
2057
December1st to 15thNight
20%
900
8%
2700
4%
900
24%
900
11%
2136
December16th to endNight
18%
960
8%
2880
3%
960
22%
960
11%
2258

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
8%9%48%7%46%5%6%7%30%
48454
Night
47%48%7%46%6%6%9%34%
47488
Cloud CoverDay
7%10%5%9%7%45%5%6%7%30%
48455
Night
47%49%8%46%5%6%8%33%
47491
TransparencyDay
52%7%16%16%6%
48114
Night
46%8%17%18%7%
47332
SeeingDay
18%20%29%20%8%2
6109
Night
10%13%34%27%11%1
15315

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
17%5%9%7%5%8%7%8%13%26%
1274
16th to endDay
7%39%9%5%7%6%7%10%30%
1536
February1st to 15thDay
19%49%7%47%7%9%10%27%
1440
16th to endDay
28%7%14%11%5%7%7%6%7%22%
1533
March1st to 15thDay
210%5%11%9%5%7%6%6%8%25%
1826
16th to endDay
420%9%13%8%45%5%6%7%13%
2156
April1st to 15thDay
8%18%8%10%7%45%5%5%7%18%
2212
16th to endDay
9%17%6%11%7%45%346%24%
2340
May1st to 15thDay
10%16%6%7%6%35%45%5%28%
2478
16th to endDay
21%11%49%7%45%45%420%
2802
June1st to 15thDay
18%10%5%9%8%45%445%21%
2700
16th to endDay
13%7%49%8%46%5%6%7%28%
2700
July1st to 15thDay
9%426%7%46%5%6%8%38%
2700
16th to endDay
6%326%5%45%5%6%8%46%
2734
August1st to 15thDay
8%5%26%6%45%5%6%7%41%
2484
16th to endDay
8%325%5%25%46%6%48%
2483
September1st to 15thDay
10%8%26%6%23347%44%
2123
16th to endDay
8%7%26%5%335%6%7%42%
1980
October1st to 15thDay
7%12%39%8%46%45%7%30%
1848
16th to endDay
47%37%7%46%7%6%10%34%
1726
November1st to 15thDay
48%48%8%5%5%6%8%8%30%
1500
16th to endDay
19%48%7%37%6%8%11%30%
1275
December1st to 15thDay
19%311%7%5%8%7%7%11%26%
1260
16th to endDay
17%5%12%9%46%6%7%11%27%
1344
January1st to 15thNight
16%6%12%10%6%9%7%7%10%21%
2676
16th to endNight
17%411%8%47%6%8%10%29%
2688
February1st to 15thNight
17%6%10%9%5%7%6%6%11%26%
2411
16th to endNight
16%5%11%9%5%7%7%7%9%27%
1938
March1st to 15thNight
27%48%8%6%7%7%9%13%26%
2133
16th to endNight
311%5%10%7%46%6%7%8%28%
2064
April1st to 15thNight
6%11%36%7%46%6%7%9%31%
1735
16th to endNight
5%10%6%8%5%46%45%7%36%
1620
May1st to 15thNight
6%11%445%35%45%8%39%
1471
16th to endNight
15%8%46%435%5%6%7%31%
1309
June1st to 15thNight
11%7%47%6%35%5%6%7%34%
1260
16th to endNight
11%435%435%6%6%8%40%
1260
July1st to 15thNight
3313425%5%5%9%56%
1260
16th to endNight
32123245%6%8%58%
1435
August1st to 15thNight
7%314325%437%56%
1476
16th to endNight
6%2122135%6%7%58%
1719
September1st to 15thNight
6%425%42235%8%55%
1836
16th to endNight
8%424425%45%9%48%
1980
October1st to 15thNight
5%7%37%6%45%5%5%9%38%
2112
16th to endNight
38%38%5%35%6%8%10%36%
2496
November1st to 15thNight
37%37%7%47%7%8%11%30%
2347
16th to endNight
19%5%8%10%5%7%6%6%10%27%
2682
December1st to 15thNight
19%5%10%12%5%7%7%7%9%22%
2700
16th to endNight
6%6%14%10%6%7%6%7%10%21%
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
16%6%11%11%6%7%5%8%10%24%
1274
16th to endDay
17%411%10%5%7%6%6%7%29%
1536
February1st to 15thDay
29%5%11%8%46%7%8%9%25%
1440
16th to endDay
18%8%15%11%5%6%5%6%8%22%
1533
March1st to 15thDay
211%6%11%10%5%5%5%7%7%24%
1826
16th to endDay
421%9%14%9%46%46%6%13%
2157
April1st to 15thDay
8%18%7%11%8%35%6%5%6%17%
2212
16th to endDay
8%17%7%11%6%46%445%24%
2340
May1st to 15thDay
9%17%5%8%6%3445%5%28%
2478
16th to endDay
20%13%5%8%8%35%45%5%19%
2802
June1st to 15thDay
18%11%5%10%8%44446%20%
2700
16th to endDay
12%8%48%8%5%6%5%6%7%27%
2700
July1st to 15thDay
8%5%25%7%46%6%6%8%38%
2700
16th to endDay
5%425%6%345%6%8%46%
2734
August1st to 15thDay
8%5%26%6%35%5%6%8%40%
2484
16th to endDay
8%325%5%25%5%6%7%47%
2483
September1st to 15thDay
10%8%26%6%2335%6%43%
2123
16th to endDay
8%8%26%5%35%45%8%42%
1980
October1st to 15thDay
8%12%410%8%45%45%7%29%
1848
16th to endDay
39%38%7%46%7%7%9%32%
1726
November1st to 15thDay
49%6%9%8%46%6%6%8%28%
1500
16th to endDay
110%5%8%9%46%6%8%8%29%
1275
December1st to 15thDay
19%6%11%9%49%5%6%8%26%
1260
16th to endDay
18%6%13%10%5%6%6%6%10%24%
1344
January1st to 15thNight
18%6%13%13%6%8%7%6%8%19%
2676
16th to endNight
17%5%12%10%47%6%7%10%26%
2688
February1st to 15thNight
28%6%13%11%46%5%6%10%24%
2411
16th to endNight
26%5%13%10%6%6%6%6%9%26%
1938
March1st to 15thNight
26%410%9%5%8%7%8%11%24%
2133
16th to endNight
310%5%11%8%45%6%6%8%28%
2067
April1st to 15thNight
6%11%48%6%46%6%7%8%29%
1735
16th to endNight
411%5%9%5%35%45%7%35%
1620
May1st to 15thNight
6%12%35%5%345%5%8%39%
1471
16th to endNight
14%10%35%5%36%47%7%31%
1309
June1st to 15thNight
11%7%36%6%36%5%6%8%33%
1260
16th to endNight
10%5%35%4346%7%8%39%
1260
July1st to 15thNight
342233446%9%55%
1260
16th to endNight
33133245%7%6%58%
1435
August1st to 15thNight
6%424335%246%56%
1476
16th to endNight
6%2133225%6%7%58%
1719
September1st to 15thNight
5%6%23423347%55%
1836
16th to endNight
8%5%2432446%8%47%
1980
October1st to 15thNight
5%8%47%7%45%5%6%8%37%
2112
16th to endNight
38%49%5%35%6%8%8%35%
2496
November1st to 15thNight
39%5%9%7%5%6%6%7%9%28%
2347
16th to endNight
19%6%11%11%46%6%5%9%25%
2682
December1st to 15thNight
210%7%12%12%47%6%6%8%20%
2700
16th to endNight
6%7%16%13%5%7%5%6%9%20%
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
54%11%18%10%31
1274
16th to endDay
51%10%17%13%42
1536
February1st to 15thDay
51%10%19%11%6%1
1440
16th to endDay
59%7%16%11%4
1533
March1st to 15thDay
57%9%18%11%2
1826
16th to endDay
72%7%12%6%1
2157
April1st to 15thDay
65%6%15%8%2
2212
16th to endDay
61%5%17%13%1
2340
May1st to 15thDay
57%5%15%17%4
2478
16th to endDay
66%6%13%10%3
2807
June1st to 15thDay
64%5%11%12%5%
2700
16th to endDay
54%5%15%17%6%
2700
July1st to 15thDay
41%6%17%22%11%1
2541
16th to endDay
34%6%12%27%15%2
2564
August1st to 15thDay
38%7%19%24%7%2
2467
16th to endDay
33%6%18%29%10%1
2483
September1st to 15thDay
41%415%22%15%
2123
16th to endDay
41%6%18%24%9%
1980
October1st to 15thDay
54%8%15%14%7%
1848
16th to endDay
45%9%22%17%3
1726
November1st to 15thDay
52%11%18%14%3
1500
16th to endDay
49%11%19%10%7%1
1275
December1st to 15thDay
55%9%17%12%4
1260
16th to endDay
53%10%17%12%6%
1344
January1st to 15thNight
61%10%12%10%31
2676
16th to endNight
50%10%17%12%6%2
2688
February1st to 15thNight
55%7%16%13%6%1
2422
16th to endNight
53%7%15%17%6%
1938
March1st to 15thNight
51%12%20%12%3
2133
16th to endNight
52%10%18%13%3
2067
April1st to 15thNight
49%8%22%13%5%
1735
16th to endNight
48%7%18%21%21
1620
May1st to 15thNight
42%6%23%22%6%
1472
16th to endNight
50%8%19%16%4
1309
June1st to 15thNight
47%8%19%17%6%
1260
16th to endNight
38%8%21%23%8%
1260
July1st to 15thNight
25%6%21%32%11%2
1190
16th to endNight
23%7%16%31%18%1
1342
August1st to 15thNight
28%5%18%33%11%1
1468
16th to endNight
22%5%18%36%15%1
1719
September1st to 15thNight
28%417%32%14%2
1836
16th to endNight
33%8%20%24%11%1
1980
October1st to 15thNight
42%9%17%21%8%
2112
16th to endNight
43%10%19%21%5%
2496
November1st to 15thNight
49%10%17%15%5%
2347
16th to endNight
55%8%14%13%6%1
2682
December1st to 15thNight
59%9%15%11%4
2700
16th to endNight
60%7%15%11%5%
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
6%6%33%33%11%8%
60
16th to endDay
7%15%46%14%10%4
64
February1st to 15thDay
8%23%41%19%5%
67
16th to endDay
10%24%34%21%6%1
192
March1st to 15thDay
22%37%28%10%
270
16th to endDay
18%31%33%14%1
288
April1st to 15thDay
21%24%32%17%3
269
16th to endDay
22%25%31%10%6%2
270
May1st to 15thDay
20%22%29%16%7%2
315
16th to endDay
25%13%19%23%14%3
517
June1st to 15thDay
22%17%23%21%12%2
495
16th to endDay
16%16%29%24%9%3
495
July1st to 15thDay
14%13%26%25%16%3
475
16th to endDay
12%22%33%19%10%1
403
August1st to 15thDay
12%14%33%28%9%2
315
16th to endDay
14%18%34%23%6%2
332
September1st to 15thDay
21%23%26%18%6%1
315
16th to endDay
19%24%30%18%6%
315
October1st to 15thDay
23%19%30%18%6%1
231
16th to endDay
15%20%33%21%5%2
144
November1st to 15thDay
21%27%32%14%4
90
16th to endDay
14%17%28%12%15%11%
63
December1st to 15thDay
10%23%23%26%10%6%
60
16th to endDay
39%54%21%10%
64
January1st to 15thNight
10%16%48%19%31
891
16th to endNight
6%15%47%24%5%
768
February1st to 15thNight
10%10%41%26%9%1
704
16th to endNight
6%10%42%29%8%1
632
March1st to 15thNight
8%19%41%22%6%
720
16th to endNight
11%14%35%29%8%1
768
April1st to 15thNight
12%16%28%30%9%1
655
16th to endNight
10%14%33%26%13%1
540
May1st to 15thNight
13%10%24%31%17%2
419
16th to endNight
19%8%19%27%22%3
375
June1st to 15thNight
16%8%26%28%18%1
360
16th to endNight
13%9%23%34%17%1
360
July1st to 15thNight
8%322%40%24%
340
16th to endNight
47%19%44%22%1
376
August1st to 15thNight
8%412%38%32%2
396
16th to endNight
9%9%20%35%23%1
573
September1st to 15thNight
9%8%22%29%21%8%
702
16th to endNight
12%9%27%28%18%4
716
October1st to 15thNight
11%13%27%33%11%2
720
16th to endNight
9%13%33%32%9%1
768
November1st to 15thNight
14%20%38%20%4
772
16th to endNight
12%15%43%21%6%1
900
December1st to 15thNight
10%15%43%23%6%1
900
16th to endNight
5%15%48%23%6%
960
Page generated at 2017-11-01 15:23:41. Version ac04

Copyright 2017 A. Danko


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