Water Valley Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Water Valley Overlook 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
48%
15461
23%
46724
17%
15417
54%
15417
28%
29133

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
27%
900
20%
2506
10%
895
36%
895
23%
1700
January16th to endNight
25%
804
22%
2388
10%
804
35%
804
21%
1608
February1st to 15thNight
25%
704
18%
2112
9%
701
33%
701
21%
1443
February16th to endNight
25%
631
22%
1893
10%
631
34%
631
21%
1280
March1st to 15thNight
29%
720
18%
2160
11%
720
35%
720
21%
1451
March16th to endNight
37%
673
19%
2029
13%
673
43%
673
25%
1342
April1st to 15thNight
41%
539
25%
1797
17%
539
53%
539
31%
1008
April16th to endNight
45%
540
24%
1800
17%
540
55%
540
30%
1045
May1st to 15thNight
46%
539
20%
1620
12%
539
53%
539
27%
1047
May16th to endNight
63%
561
19%
1683
15%
561
66%
561
31%
1035
June1st to 15thNight
71%
540
21%
1536
16%
540
74%
540
37%
917
June16th to endNight
80%
540
25%
1440
19%
540
82%
540
45%
816
July1st to 15thNight
72%
510
17%
1360
14%
510
73%
510
35%
864
July16th to endNight
79%
564
21%
1551
20%
531
81%
531
39%
901
August1st to 15thNight
79%
539
21%
1778
24%
536
79%
536
34%
998
August16th to endNight
73%
573
22%
1910
27%
573
74%
573
30%
1139
September1st to 15thNight
65%
580
22%
1817
22%
580
67%
580
30%
1106
September16th to endNight
63%
657
29%
1815
23%
657
65%
657
36%
1102
October1st to 15thNight
56%
660
34%
1815
27%
660
61%
660
38%
1073
October16th to endNight
51%
704
31%
2187
25%
704
59%
704
33%
1268
November1st to 15thNight
50%
700
30%
2276
27%
700
59%
700
34%
1260
November16th to endNight
40%
720
26%
2340
20%
720
50%
720
28%
1401
December1st to 15thNight
35%
720
21%
2340
15%
720
43%
720
21%
1547
December16th to endNight
30%
843
19%
2571
12%
843
38%
843
20%
1782

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
13%5%25%5%3445%7%40%
47924
Night
12%5%25%42445%7%45%
46911
TransparencyDay
41%6%10%21%16%3
47614
Night
37%5%10%22%19%4
46725
SeeingDay
14%418%24%24%14%
5542
Night
15%6%23%29%21%3
15464

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
19%8%25%424446%38%
1432
16th to endDay
18%6%25%423345%42%
1829
February1st to 15thDay
18%9%35%423335%38%
1750
16th to endDay
16%7%26%5%35%446%37%
1580
March1st to 15thDay
19%8%35%423445%36%
1800
16th to endDay
16%5%37%6%3445%7%35%
2203
April1st to 15thDay
12%5%25%42445%6%46%
2151
16th to endDay
14%5%26%5%3445%7%40%
2160
May1st to 15thDay
17%5%25%5%3435%7%39%
2328
16th to endDay
11%6%26%5%35%5%6%8%38%
2431
June1st to 15thDay
7%5%25%5%45%5%6%10%41%
2420
16th to endDay
5%215%6%46%6%7%10%42%
2520
July1st to 15thDay
10%326%6%47%6%7%9%34%
2520
16th to endDay
7%425%6%46%7%7%10%36%
2507
August1st to 15thDay
6%335%6%46%7%7%9%39%
2168
16th to endDay
10%5%25%6%45%6%6%8%36%
2292
September1st to 15thDay
11%5%25%6%35%5%6%8%37%
2050
16th to endDay
11%4145%23447%49%
1815
October1st to 15thDay
12%424324347%50%
1815
16th to endDay
14%413323435%53%
1681
November1st to 15thDay
13%5%23323345%53%
1582
16th to endDay
16%5%23223345%49%
1620
December1st to 15thDay
21%7%36%42434435%
1620
16th to endDay
21%9%35%323236%37%
1650
January1st to 15thNight
17%8%25%323345%40%
2506
16th to endNight
18%7%25%4245%4439%
2388
February1st to 15thNight
17%10%35%5%33345%38%
2103
16th to endNight
17%6%36%5%3335%6%37%
1893
March1st to 15thNight
17%6%25%434446%39%
2160
16th to endNight
13%6%35%5%35%447%40%
2029
April1st to 15thNight
11%424323447%50%
1797
16th to endNight
11%423325%46%6%47%
1800
May1st to 15thNight
10%5%36%435%45%6%44%
1619
16th to endNight
7%4245%3446%9%46%
1682
June1st to 15thNight
43235%25%5%6%10%48%
1536
16th to endNight
21143346%8%12%52%
1440
July1st to 15thNight
7%325%5%45%5%6%12%42%
1440
16th to endNight
4213425%6%7%12%47%
1658
August1st to 15thNight
42145%35%6%8%10%47%
1789
16th to endNight
7%326%42448%11%42%
1910
September1st to 15thNight
10%5%25%42446%7%46%
1817
16th to endNight
9%5%1442345%6%52%
1815
October1st to 15thNight
11%424423346%54%
1815
16th to endNight
13%5%13322345%53%
2187
November1st to 15thNight
11%424323346%53%
2276
16th to endNight
16%5%24313335%48%
2340
December1st to 15thNight
17%8%36%414335%39%
2340
16th to endNight
22%8%24424435%37%
2571

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
47%37%21%15%3
1433
16th to endDay
43%48%25%16%2
1829
February1st to 15thDay
48%38%21%14%3
1752
16th to endDay
47%310%21%13%3
1580
March1st to 15thDay
49%5%7%17%14%4
1800
16th to endDay
47%5%11%21%12%
2204
April1st to 15thDay
37%6%9%21%20%4
2151
16th to endDay
42%5%8%22%17%3
2160
May1st to 15thDay
45%5%9%21%15%2
2328
16th to endDay
41%8%12%22%12%1
2435
June1st to 15thDay
35%8%13%24%16%1
2420
16th to endDay
34%8%13%19%19%4
2520
July1st to 15thDay
41%10%15%18%10%4
2371
16th to endDay
37%11%17%22%10%1
2351
August1st to 15thDay
35%10%15%20%14%2
2155
16th to endDay
42%7%12%20%14%2
2292
September1st to 15thDay
41%9%10%20%13%4
2050
16th to endDay
34%5%9%20%24%4
1815
October1st to 15thDay
35%47%21%25%5%
1815
16th to endDay
34%36%21%28%6%
1681
November1st to 15thDay
34%36%20%27%8%
1582
16th to endDay
37%37%25%20%5%
1620
December1st to 15thDay
50%46%20%14%3
1620
16th to endDay
48%410%19%13%2
1650
January1st to 15thNight
46%38%20%18%2
2506
16th to endNight
47%47%19%17%3
2388
February1st to 15thNight
49%310%20%14%2
2112
16th to endNight
47%48%21%16%2
1893
March1st to 15thNight
45%5%8%17%17%5%
2160
16th to endNight
43%5%11%23%14%1
2029
April1st to 15thNight
33%311%24%21%5%
1797
16th to endNight
34%5%10%24%21%3
1800
May1st to 15thNight
39%7%10%21%18%2
1620
16th to endNight
32%9%14%23%15%4
1684
June1st to 15thNight
29%8%14%27%17%2
1536
16th to endNight
22%8%17%27%18%4
1440
July1st to 15thNight
31%9%16%23%14%4
1360
16th to endNight
25%9%19%28%14%2
1551
August1st to 15thNight
26%10%16%25%18%2
1778
16th to endNight
32%9%14%24%15%4
1910
September1st to 15thNight
34%7%13%21%18%4
1817
16th to endNight
32%6%8%20%25%7%
1815
October1st to 15thNight
31%47%21%26%8%
1815
16th to endNight
33%4420%27%9%
2187
November1st to 15thNight
31%36%20%26%11%
2276
16th to endNight
38%37%22%24%4
2340
December1st to 15thNight
45%5%8%19%16%4
2340
16th to endNight
49%48%18%15%2
2571

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
26%7%43%10%11%1
90
16th to endDay
23%11%42%16%5%
96
February1st to 15thDay
24%16%40%13%41
90
16th to endDay
32%11%28%19%8%
81
March1st to 15thDay
27%17%30%20%4
90
16th to endDay
17%8%29%29%12%2
275
April1st to 15thDay
14%11%24%30%15%3
270
16th to endDay
18%324%30%18%4
270
May1st to 15thDay
18%8%23%25%14%9%
288
16th to endDay
15%219%27%19%14%
331
June1st to 15thDay
9%113%20%31%24%
395
16th to endDay
6%114%27%31%18%
495
July1st to 15thDay
10%112%32%28%15%
475
16th to endDay
6%8%16%31%36%
367
August1st to 15thDay
7%7%23%35%25%
313
16th to endDay
14%6%20%40%18%
332
September1st to 15thDay
12%28%20%33%23%
299
16th to endDay
14%211%26%33%12%
254
October1st to 15thDay
13%123%26%23%11%
255
16th to endDay
20%117%30%22%7%
110
November1st to 15thDay
16%7%24%30%18%2
90
16th to endDay
24%8%34%15%12%4
90
December1st to 15thDay
23%10%36%21%7%1
90
16th to endDay
20%11%46%17%21
96
January1st to 15thNight
23%15%30%25%5%
900
16th to endNight
22%10%38%26%2
804
February1st to 15thNight
23%12%35%25%3
704
16th to endNight
22%15%33%26%2
631
March1st to 15thNight
21%12%33%27%5%
720
16th to endNight
16%9%32%28%12%1
673
April1st to 15thNight
13%10%31%30%11%2
539
16th to endNight
13%6%31%34%13%1
540
May1st to 15thNight
12%5%28%31%19%1
540
16th to endNight
8%115%37%31%4
563
June1st to 15thNight
7%12%35%37%6%
540
16th to endNight
29%34%44%8%
540
July1st to 15thNight
7%9%30%42%8%
510
16th to endNight
47%25%48%14%
564
August1st to 15thNight
5%330%49%10%
539
16th to endNight
8%5%33%45%6%
573
September1st to 15thNight
11%111%28%40%7%
580
16th to endNight
11%214%30%36%3
657
October1st to 15thNight
13%320%29%28%4
660
16th to endNight
16%5%22%32%21%1
704
November1st to 15thNight
13%6%25%31%20%3
700
16th to endNight
20%9%27%29%12%
720
December1st to 15thNight
20%12%27%28%10%
720
16th to endNight
26%8%31%28%4
843
Page generated at 2017-09-13 06:39:17. Version ac04

Copyright 2017 A. Danko


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