White Sands National Monument
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the White Sands National Monument clear sky chart from 2005-11-05 to 2017-08-12.

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
70%
15359
34%
46717
27%
15320
77%
15320
51%
22673

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
67%
716
34%
2327
30%
716
76%
716
50%
1101
January16th to endNight
65%
768
37%
2496
32%
768
75%
768
51%
1168
February1st to 15thNight
63%
701
35%
2164
27%
699
74%
699
55%
984
February16th to endNight
53%
632
38%
1894
25%
632
67%
632
53%
917
March1st to 15thNight
59%
720
37%
2004
24%
720
69%
720
55%
998
March16th to endNight
62%
732
38%
2076
24%
732
73%
732
59%
982
April1st to 15thNight
53%
539
36%
1798
26%
539
68%
539
51%
808
April16th to endNight
55%
540
40%
1800
29%
540
74%
540
61%
726
May1st to 15thNight
60%
540
32%
1799
27%
539
73%
539
58%
767
May16th to endNight
68%
561
31%
1785
27%
561
78%
561
54%
818
June1st to 15thNight
79%
540
31%
1485
27%
540
81%
540
59%
737
June16th to endNight
81%
540
24%
1579
22%
540
83%
540
51%
796
July1st to 15thNight
82%
510
24%
1530
23%
510
82%
510
42%
839
July16th to endNight
83%
564
25%
1593
24%
531
84%
531
37%
904
August1st to 15thNight
83%
527
21%
1728
26%
524
83%
524
36%
972
August16th to endNight
81%
525
23%
1750
28%
525
82%
525
35%
967
September1st to 15thNight
77%
495
26%
1650
29%
495
77%
495
32%
944
September16th to endNight
79%
517
35%
1768
34%
517
83%
517
50%
808
October1st to 15thNight
78%
660
36%
1980
30%
660
80%
660
55%
938
October16th to endNight
79%
704
41%
2112
30%
704
85%
704
65%
914
November1st to 15thNight
76%
700
42%
2100
31%
700
83%
700
65%
912
November16th to endNight
68%
879
38%
2319
25%
879
75%
879
57%
1195
December1st to 15thNight
67%
900
36%
2403
26%
900
73%
900
56%
1237
December16th to endNight
64%
849
35%
2577
28%
849
71%
849
51%
1241

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
3212223347%66%
47215
Night
4212223347%64%
46916
TransparencyDay
17%48%17%27%25%
46911
Night
18%48%15%26%26%
46722
SeeingDay
45%16%30%29%13%
4997
Night
4218%44%27%2
15368

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
4312213337%67%
1611
16th to endDay
6%212212237%66%
1728
February1st to 15thDay
2212222235%72%
1695
16th to endDay
311121333373%
1580
March1st to 15thDay
3212323336%67%
1953
16th to endDay
222213235%72%
2146
April1st to 15thDay
2211213345%71%
2150
16th to endDay
11111122382%
2160
May1st to 15thDay
111213345%73%
2151
16th to endDay
21112336%75%
2324
June1st to 15thDay
111113345%74%
2464
16th to endDay
21222236%8%66%
2369
July1st to 15thDay
42125%35%6%8%11%47%
2340
16th to endDay
43135%45%6%9%12%43%
2467
August1st to 15thDay
4223435%5%7%9%50%
2134
16th to endDay
3213435%5%6%11%51%
2100
September1st to 15thDay
9%323424448%50%
1980
16th to endDay
422212236%70%
1860
October1st to 15thDay
3212213236%70%
1650
16th to endDay
21121123378%
1760
November1st to 15thDay
111212235%76%
1759
16th to endDay
5%3221333370%
1626
December1st to 15thDay
422212238%67%
1555
16th to endDay
5%313312338%63%
1653
January1st to 15thNight
4312222345%66%
2327
16th to endNight
7%212212335%67%
2496
February1st to 15thNight
421212345%69%
2156
16th to endNight
5%313212345%67%
1894
March1st to 15thNight
5%312213246%66%
2004
16th to endNight
321221232472%
2076
April1st to 15thNight
321221235%6%66%
1798
16th to endNight
21211234473%
1800
May1st to 15thNight
221223335%72%
1799
16th to endNight
222223346%69%
1785
June1st to 15thNight
21222445%6%66%
1485
16th to endNight
21123245%7%10%58%
1579
July1st to 15thNight
3223335%5%6%11%50%
1620
16th to endNight
2214436%8%8%12%46%
1701
August1st to 15thNight
42145%36%7%9%12%44%
1737
16th to endNight
33144247%7%12%47%
1750
September1st to 15thNight
6%324445%5%6%10%46%
1650
16th to endNight
5%22222336%66%
1768
October1st to 15thNight
3112223246%68%
1980
16th to endNight
31111223378%
2112
November1st to 15thNight
111122236%74%
2100
16th to endNight
5%312212235%69%
2319
December1st to 15thNight
6%213212337%66%
2403
16th to endNight
5%213213446%64%
2577

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
19%37%19%33%17%
1612
16th to endDay
19%26%19%35%17%
1728
February1st to 15thDay
15%2418%28%29%
1696
16th to endDay
15%2312%37%27%
1580
March1st to 15thDay
18%2414%30%29%
1953
16th to endDay
14%2411%32%35%
2146
April1st to 15thDay
14%2411%30%36%
2150
16th to endDay
8%138%26%50%
2160
May1st to 15thDay
12%36%11%23%42%
2151
16th to endDay
11%35%11%23%44%
2327
June1st to 15thDay
10%26%11%21%45%
2464
16th to endDay
15%49%13%22%33%
2369
July1st to 15thDay
24%9%15%21%15%14%
2201
16th to endDay
26%10%21%23%14%2
2312
August1st to 15thDay
26%8%15%25%18%6%
2119
16th to endDay
24%9%16%23%19%7%
2100
September1st to 15thDay
29%7%11%22%19%9%
1980
16th to endDay
17%36%19%32%21%
1860
October1st to 15thDay
16%37%13%31%28%
1650
16th to endDay
11%1317%33%32%
1760
November1st to 15thDay
11%26%17%33%28%
1759
16th to endDay
17%2415%36%22%
1626
December1st to 15thDay
18%27%22%37%11%
1555
16th to endDay
20%49%25%33%7%
1653
January1st to 15thNight
19%36%17%34%18%
2327
16th to endNight
19%25%14%36%19%
2496
February1st to 15thNight
16%27%15%25%32%
2166
16th to endNight
19%25%8%34%29%
1894
March1st to 15thNight
19%25%12%30%30%
2004
16th to endNight
16%25%9%29%37%
2076
April1st to 15thNight
17%36%9%29%33%
1798
16th to endNight
12%25%10%24%46%
1800
May1st to 15thNight
14%25%11%23%41%
1800
16th to endNight
17%37%11%19%40%
1787
June1st to 15thNight
15%47%13%15%44%
1485
16th to endNight
18%5%11%17%18%27%
1579
July1st to 15thNight
24%6%14%22%20%12%
1530
16th to endNight
25%10%19%26%15%3
1593
August1st to 15thNight
26%9%17%25%15%5%
1728
16th to endNight
26%8%14%24%19%6%
1750
September1st to 15thNight
31%6%15%17%16%11%
1650
16th to endNight
18%38%17%29%22%
1768
October1st to 15thNight
16%46%14%24%33%
1980
16th to endNight
12%2414%26%39%
2112
November1st to 15thNight
12%2416%32%32%
2100
16th to endNight
18%2411%31%30%
2319
December1st to 15thNight
19%27%19%32%19%
2403
16th to endNight
19%39%23%34%10%
2577

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
14%218%41%20%3
90
16th to endDay
45%21%41%18%8%
96
February1st to 15thDay
3311%36%34%11%
90
16th to endDay
4419%35%24%9%
81
March1st to 15thDay
411%27%34%16%4
243
16th to endDay
317%26%29%17%5%
288
April1st to 15thDay
416%31%30%15%1
269
16th to endDay
217%39%25%12%2
270
May1st to 15thDay
113%34%32%14%3
288
16th to endDay
27%28%40%18%2
330
June1st to 15thDay
2112%38%32%11%
439
16th to endDay
17%29%41%18%
344
July1st to 15thDay
2322%52%17%
305
16th to endDay
3322%38%31%
327
August1st to 15thDay
5%217%39%35%
300
16th to endDay
35%23%39%26%
268
September1st to 15thDay
11%7%25%38%16%
255
16th to endDay
7%16%29%46%9%
162
October1st to 15thDay
11%17%24%28%26%
90
16th to endDay
9%425%32%29%
96
November1st to 15thDay
5%211%30%34%16%
90
16th to endDay
12%6%22%28%25%4
90
December1st to 15thDay
7%13%36%31%11%
90
16th to endDay
7%9%20%47%12%2
96
January1st to 15thNight
5%20%48%22%1
720
16th to endNight
7%221%49%18%1
768
February1st to 15thNight
6%224%45%20%1
704
16th to endNight
5%434%47%9%
632
March1st to 15thNight
5%327%46%16%
720
16th to endNight
3327%48%15%
732
April1st to 15thNight
46%33%45%11%
539
16th to endNight
2434%45%11%
540
May1st to 15thNight
3230%53%10%
540
16th to endNight
3121%55%17%
563
June1st to 15thNight
2113%54%27%
540
16th to endNight
29%50%35%1
540
July1st to 15thNight
3440%46%3
510
16th to endNight
3229%56%6%
564
August1st to 15thNight
4221%60%10%
527
16th to endNight
4230%54%8%
525
September1st to 15thNight
7%337%46%4
495
16th to endNight
5%8%45%36%3
517
October1st to 15thNight
3112%48%31%1
660
16th to endNight
313%40%36%5%
704
November1st to 15thNight
316%42%34%2
700
16th to endNight
6%218%39%30%2
879
December1st to 15thNight
7%217%47%23%
900
16th to endNight
5%322%51%16%
849
Page generated at 2017-08-13 12:16:53. Version ac04

Copyright 2017 A. Danko


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