Emmett
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Emmett clear sky chart from 2005-11-05 to 2017-09-16.

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
58%
14755
19%
46815
18%
14729
61%
14729
28%
29049

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
42%
716
7%
2506
8%
716
43%
716
11%
1971
January16th to endNight
48%
768
8%
2688
9%
768
49%
768
14%
2008
February1st to 15thNight
46%
698
8%
2262
8%
696
49%
696
17%
1637
February16th to endNight
46%
632
13%
1895
12%
632
48%
632
18%
1366
March1st to 15thNight
45%
720
10%
2160
9%
720
47%
720
19%
1549
March16th to endNight
44%
768
15%
2031
10%
768
47%
768
25%
1410
April1st to 15thNight
50%
719
19%
1799
9%
719
53%
719
29%
1220
April16th to endNight
54%
576
25%
1656
16%
576
58%
576
34%
977
May1st to 15thNight
58%
527
22%
1607
18%
527
62%
527
40%
860
May16th to endNight
62%
374
19%
1496
26%
374
65%
374
25%
827
June1st to 15thNight
58%
360
16%
1440
21%
360
65%
360
27%
790
June16th to endNight
68%
360
25%
1440
36%
360
75%
360
44%
609
July1st to 15thNight
80%
340
24%
1360
36%
340
85%
340
54%
513
July16th to endNight
79%
376
34%
1416
45%
354
85%
354
58%
505
August1st to 15thNight
80%
467
31%
1540
31%
465
83%
465
53%
688
August16th to endNight
81%
702
37%
1848
25%
702
83%
702
64%
888
September1st to 15thNight
83%
720
36%
1842
24%
720
86%
720
67%
899
September16th to endNight
72%
660
35%
1826
30%
660
74%
660
47%
993
October1st to 15thNight
67%
660
27%
1856
24%
660
71%
660
40%
1073
October16th to endNight
63%
704
23%
2288
23%
704
66%
704
30%
1353
November1st to 15thNight
56%
700
21%
2275
22%
700
59%
700
26%
1436
November16th to endNight
50%
720
13%
2376
11%
720
53%
720
20%
1609
December1st to 15thNight
50%
720
10%
2520
9%
720
53%
720
15%
1826
December16th to endNight
40%
768
9%
2688
10%
768
42%
768
13%
2042

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%5%24424446%49%
47956
Night
12%6%25%424446%45%
46988
TransparencyDay
34%5%12%20%17%10%
47627
Night
39%5%12%19%15%8%
46816
SeeingDay
11%6%19%29%24%9%
5378
Night
15%215%36%26%3
14767

By Month

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
19%9%5%9%8%5%6%6%5%6%17%
1432
16th to endDay
16%12%6%11%9%45%445%18%
1536
February1st to 15thDay
15%10%47%6%36%5%47%28%
1599
16th to endDay
12%9%36%7%36%46%8%31%
1579
March1st to 15thDay
16%9%36%5%25%6%5%8%30%
1800
16th to endDay
15%8%25%5%35%46%7%34%
2189
April1st to 15thDay
9%6%36%6%45%45%9%39%
2149
16th to endDay
9%5%25%42445%7%49%
2303
May1st to 15thDay
6%41342445%6%54%
2340
16th to endDay
7%425%5%35%45%8%46%
2615
June1st to 15thDay
9%5%244245%6%8%45%
2520
16th to endDay
3212213345%69%
2520
July1st to 15thDay
3212212345%71%
2520
16th to endDay
11121222477%
2657
August1st to 15thDay
3112212245%70%
2409
16th to endDay
22121233475%
2351
September1st to 15thDay
32221223473%
2118
16th to endDay
8%312222337%62%
1823
October1st to 15thDay
8%31332445%7%53%
1771
16th to endDay
10%6%26%5%2446%7%42%
1584
November1st to 15thDay
14%8%2442445%8%39%
1584
16th to endDay
16%7%47%7%36%5%47%28%
1581
December1st to 15thDay
19%9%48%6%4445%7%26%
1440
16th to endDay
22%12%48%8%44445%19%
1536
January1st to 15thNight
19%12%49%7%35%435%23%
2506
16th to endNight
17%9%49%5%34346%29%
2688
February1st to 15thNight
18%10%35%5%345%46%32%
2251
16th to endNight
14%10%46%5%35%5%6%7%30%
1895
March1st to 15thNight
16%11%46%5%34436%32%
2160
16th to endNight
15%8%35%5%3445%7%36%
2031
April1st to 15thNight
12%6%36%5%345%5%7%40%
1799
16th to endNight
10%5%1442445%5%51%
1656
May1st to 15thNight
5%423324446%56%
1607
16th to endNight
6%435%5%35%5%6%9%43%
1496
June1st to 15thNight
9%3235%3436%6%50%
1440
16th to endNight
4213223347%64%
1440
July1st to 15thNight
1112222348%68%
1440
16th to endNight
211211234375%
1512
August1st to 15thNight
2211223346%68%
1548
16th to endNight
221121333474%
1848
September1st to 15thNight
21122346%73%
1842
16th to endNight
7%41332233463%
1826
October1st to 15thNight
8%3245%24345%56%
1856
16th to endNight
12%5%2343346%8%45%
2288
November1st to 15thNight
18%5%2442435%7%41%
2275
16th to endNight
18%7%25%5%34346%37%
2376
December1st to 15thNight
19%10%36%4245%5%6%32%
2520
16th to endNight
23%12%45%5%3444427%
2688

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
61%11%16%9%
1432
16th to endDay
66%8%14%9%
1536
February1st to 15thDay
53%11%16%16%2
1599
16th to endDay
49%7%19%17%4
1579
March1st to 15thDay
50%7%18%17%5%
1800
16th to endDay
47%5%17%21%7%
2189
April1st to 15thDay
41%6%17%24%10%1
2149
16th to endDay
33%412%30%16%2
2303
May1st to 15thDay
27%311%31%21%4
2340
16th to endDay
33%5%14%26%16%4
2619
June1st to 15thDay
34%411%23%20%5%
2520
16th to endDay
17%26%22%32%18%
2520
July1st to 15thDay
14%25%15%29%32%
2371
16th to endDay
10%229%28%46%
2490
August1st to 15thDay
16%25%16%28%30%
2392
16th to endDay
14%2418%35%25%
2351
September1st to 15thDay
14%2419%34%23%
2118
16th to endDay
23%39%28%27%7%
1823
October1st to 15thDay
29%315%28%19%2
1771
16th to endDay
39%7%15%26%12%
1584
November1st to 15thDay
41%8%20%22%6%
1584
16th to endDay
53%6%18%15%4
1581
December1st to 15thDay
57%9%19%11%2
1440
16th to endDay
65%7%13%10%2
1536
January1st to 15thNight
61%7%14%13%2
2506
16th to endNight
54%9%16%15%3
2688
February1st to 15thNight
52%6%18%17%4
2262
16th to endNight
52%5%17%18%4
1895
March1st to 15thNight
52%413%21%6%1
2160
16th to endNight
47%314%23%10%
2031
April1st to 15thNight
41%5%11%25%14%1
1799
16th to endNight
33%39%27%23%2
1656
May1st to 15thNight
27%39%23%32%3
1608
16th to endNight
34%6%9%27%16%6%
1496
June1st to 15thNight
33%5%10%22%21%5%
1440
16th to endNight
19%35%20%30%19%
1440
July1st to 15thNight
13%35%14%28%34%
1360
16th to endNight
12%239%24%47%
1416
August1st to 15thNight
16%46%13%24%34%
1540
16th to endNight
14%2315%28%36%
1848
September1st to 15thNight
12%25%15%31%31%
1842
16th to endNight
26%25%19%29%17%
1826
October1st to 15thNight
30%39%27%21%7%
1856
16th to endNight
36%413%23%20%1
2288
November1st to 15thNight
41%414%23%15%
2275
16th to endNight
48%5%16%22%6%
2376
December1st to 15thNight
52%8%17%15%5%
2520
16th to endNight
59%5%16%15%2
2688

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
30%11%15%26%16%
60
16th to endDay
26%6%6%35%18%6%
64
February1st to 15thDay
22%318%20%24%10%
174
16th to endDay
22%10%21%28%12%5%
238
March1st to 15thDay
25%11%24%23%13%2
270
16th to endDay
20%12%27%27%10%1
288
April1st to 15thDay
10%17%27%17%16%10%
269
16th to endDay
10%12%30%25%16%4
270
May1st to 15thDay
7%11%28%29%16%5%
288
16th to endDay
10%5%16%30%23%14%
330
June1st to 15thDay
8%5%22%35%20%8%
315
16th to endDay
46%19%32%27%8%
315
July1st to 15thDay
4313%31%34%12%
305
16th to endDay
1115%41%31%8%
327
August1st to 15thDay
3116%37%33%6%
315
16th to endDay
3211%31%35%16%
332
September1st to 15thDay
6%114%22%31%23%
315
16th to endDay
9%111%29%31%17%
258
October1st to 15thDay
11%320%22%30%10%
252
16th to endDay
19%419%30%18%7%
96
November1st to 15thDay
13%13%32%40%1
90
16th to endDay
20%9%26%31%10%1
83
December1st to 15thDay
38%5%20%30%6%
60
16th to endDay
37%412%23%17%4
64
January1st to 15thNight
23%215%32%21%3
720
16th to endNight
22%111%32%28%4
768
February1st to 15thNight
22%215%33%22%3
704
16th to endNight
20%420%32%20%2
632
March1st to 15thNight
21%420%32%18%2
720
16th to endNight
19%5%24%35%12%1
768
April1st to 15thNight
14%421%35%21%2
719
16th to endNight
13%6%20%35%22%2
576
May1st to 15thNight
9%422%36%23%3
528
16th to endNight
7%5%16%29%35%5%
375
June1st to 15thNight
11%316%36%27%3
360
16th to endNight
5%219%37%33%2
360
July1st to 15thNight
2110%46%38%1
340
16th to endNight
3112%43%39%1
376
August1st to 15thNight
3110%43%39%1
467
16th to endNight
319%39%39%6%
702
September1st to 15thNight
48%36%43%7%
720
16th to endNight
11%110%31%35%9%
660
October1st to 15thNight
9%113%43%26%5%
660
16th to endNight
15%112%36%29%5%
704
November1st to 15thNight
20%214%35%25%2
700
16th to endNight
21%315%34%19%5%
720
December1st to 15thNight
23%212%39%20%2
720
16th to endNight
30%214%36%14%2
768
Page generated at 2017-09-17 10:05:40. Version ac04

Copyright 2017 A. Danko


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