Navajo Flats
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Navajo Flats clear sky chart from 2005-11-05 to 2017-12-04.

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
76%
15945
33%
47848
30%
15909
79%
15909
52%
23291

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
66%
716
24%
2400
25%
716
69%
716
34%
1316
January16th to endNight
63%
768
28%
2496
28%
768
67%
768
34%
1413
February1st to 15thNight
66%
700
29%
2170
30%
700
69%
700
36%
1211
February16th to endNight
63%
632
27%
1895
28%
632
67%
632
34%
1110
March1st to 15thNight
67%
720
24%
2082
22%
720
71%
720
41%
1160
March16th to endNight
66%
768
25%
2035
20%
768
70%
768
44%
1149
April1st to 15thNight
63%
719
29%
1799
18%
719
67%
719
47%
1028
April16th to endNight
69%
720
31%
1800
15%
720
74%
720
59%
923
May1st to 15thNight
82%
706
31%
1786
20%
706
83%
706
67%
864
May16th to endNight
79%
442
38%
1566
35%
442
83%
442
62%
589
June1st to 15thNight
86%
360
36%
1440
41%
360
91%
360
66%
477
June16th to endNight
95%
360
43%
1440
53%
360
96%
360
87%
402
July1st to 15thNight
97%
357
38%
1377
45%
357
97%
357
82%
414
July16th to endNight
92%
564
41%
1593
36%
531
92%
531
72%
650
August1st to 15thNight
95%
681
41%
1755
28%
678
95%
678
85%
744
August16th to endNight
95%
764
47%
1910
31%
764
95%
764
86%
829
September1st to 15thNight
92%
720
43%
1800
34%
720
93%
720
77%
837
September16th to endNight
92%
716
50%
1933
47%
716
94%
716
82%
808
October1st to 15thNight
80%
720
34%
2136
36%
720
83%
720
58%
990
October16th to endNight
82%
768
42%
2304
45%
768
85%
768
56%
1067
November1st to 15thNight
78%
760
34%
2414
36%
760
81%
760
52%
1130
November16th to endNight
72%
780
31%
2535
33%
780
77%
780
43%
1284
December1st to 15thNight
68%
736
28%
2494
28%
736
71%
736
34%
1355
December16th to endNight
58%
768
25%
2688
25%
768
64%
768
29%
1541

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
4212213335%67%
48645
Night
3213213346%66%
48034
TransparencyDay
19%26%19%28%22%
48329
Night
19%37%19%27%22%
47849
SeeingDay
5%8%20%34%23%7%
6291
Night
438%33%38%10%
15955

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
7%414425%5%5%6%52%
1537
16th to endDay
11%5%25%5%24335%49%
1728
February1st to 15thDay
11%6%34313446%50%
1691
16th to endDay
10%6%35%424446%44%
1579
March1st to 15thDay
7%4145%35%5%6%9%47%
1876
16th to endDay
7%5%244345%37%51%
2187
April1st to 15thDay
7%5%34323437%54%
2149
16th to endDay
421232335%7%62%
2160
May1st to 15thDay
212213346%70%
2163
16th to endDay
21221235%6%72%
2546
June1st to 15thDay
111112245%75%
2520
16th to endDay
1111287%
2520
July1st to 15thDay
1111112482%
2499
16th to endDay
11112225%78%
2468
August1st to 15thDay
11122485%
2196
16th to endDay
11121387%
2292
September1st to 15thDay
11112484%
2160
16th to endDay
1111122480%
2025
October1st to 15thDay
2112213336%69%
1821
16th to endDay
1212423446%66%
1920
November1st to 15thDay
5%31342225%5%62%
1773
16th to endDay
42134246%5%7%56%
1755
December1st to 15thDay
7%425%445%5%5%7%47%
1544
16th to endDay
10%6%36%32245%6%47%
1536
January1st to 15thNight
6%5%244245%48%50%
2400
16th to endNight
8%5%24424447%50%
2496
February1st to 15thNight
6%5%34425%35%6%53%
2159
16th to endNight
8%425%434445%52%
1895
March1st to 15thNight
44134245%5%7%54%
2082
16th to endNight
5%32342445%9%55%
2035
April1st to 15thNight
5%413323336%61%
1799
16th to endNight
2212213347%68%
1800
May1st to 15thNight
112112348%72%
1786
16th to endNight
111112236%77%
1565
June1st to 15thNight
1112145%79%
1440
16th to endNight
1291%
1440
July1st to 15thNight
111487%
1458
16th to endNight
11121122381%
1701
August1st to 15thNight
1112288%
1764
16th to endNight
1112388%
1910
September1st to 15thNight
111212483%
1800
16th to endNight
1122385%
1933
October1st to 15thNight
2212212235%71%
2136
16th to endNight
1212223245%69%
2304
November1st to 15thNight
3213312346%66%
2414
16th to endNight
432332446%8%56%
2535
December1st to 15thNight
6%4244345%5%8%50%
2494
16th to endNight
9%5%25%423347%48%
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
30%47%22%22%12%
1537
16th to endDay
37%38%14%17%17%
1728
February1st to 15thDay
35%26%20%22%11%
1691
16th to endDay
39%38%23%20%4
1579
March1st to 15thDay
32%412%21%18%10%
1876
16th to endDay
32%312%23%20%6%
2187
April1st to 15thDay
31%310%25%21%7%
2149
16th to endDay
21%310%27%27%10%
2160
May1st to 15thDay
14%27%27%35%12%
2163
16th to endDay
12%38%33%33%8%
2549
June1st to 15thDay
12%27%20%33%23%
2520
16th to endDay
6%117%37%45%
2520
July1st to 15thDay
7%217%27%53%
2351
16th to endDay
10%2412%28%41%
2313
August1st to 15thDay
5%110%36%44%
2180
16th to endDay
5%110%42%40%
2292
September1st to 15thDay
6%314%33%41%
2160
16th to endDay
9%1119%44%24%
2025
October1st to 15thDay
17%25%22%27%25%
1821
16th to endDay
18%45%18%29%24%
1920
November1st to 15thDay
23%29%21%28%13%
1773
16th to endDay
24%49%21%25%15%
1755
December1st to 15thDay
35%48%18%21%12%
1544
16th to endDay
36%310%20%19%8%
1536
January1st to 15thNight
31%39%20%22%12%
2400
16th to endNight
33%38%15%19%18%
2496
February1st to 15thNight
30%48%20%25%10%
2170
16th to endNight
33%38%25%23%5%
1895
March1st to 15thNight
26%5%13%24%19%9%
2082
16th to endNight
24%416%23%22%7%
2035
April1st to 15thNight
25%313%28%22%7%
1799
16th to endNight
15%314%26%29%10%
1800
May1st to 15thNight
11%39%25%36%13%
1787
16th to endNight
10%26%32%35%12%
1566
June1st to 15thNight
8%29%19%31%28%
1440
16th to endNight
228%33%51%
1440
July1st to 15thNight
31111%22%60%
1377
16th to endNight
9%119%24%52%
1593
August1st to 15thNight
5%7%27%58%
1755
16th to endNight
46%37%49%
1910
September1st to 15thNight
8%129%28%47%
1800
16th to endNight
6%1117%44%28%
1933
October1st to 15thNight
16%25%20%28%26%
2136
16th to endNight
16%3421%32%22%
2304
November1st to 15thNight
18%39%24%28%14%
2414
16th to endNight
24%49%20%27%14%
2535
December1st to 15thNight
29%5%9%19%23%12%
2494
16th to endNight
36%311%20%18%9%
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
15%13%29%30%9%1
165
16th to endDay
14%12%28%25%16%2
256
February1st to 15thDay
10%14%25%30%16%2
256
16th to endDay
15%17%29%25%9%2
238
March1st to 15thDay
10%15%29%30%14%
270
16th to endDay
7%18%27%32%13%
288
April1st to 15thDay
13%16%32%22%13%2
269
16th to endDay
5%20%34%25%11%1
270
May1st to 15thDay
5%12%29%33%13%5%
288
16th to endDay
39%25%34%20%6%
330
June1st to 15thDay
17%19%40%23%6%
315
16th to endDay
111%38%31%16%
315
July1st to 15thDay
17%38%35%16%
305
16th to endDay
1437%37%19%
327
August1st to 15thDay
28%43%31%13%
315
16th to endDay
5%34%38%20%
332
September1st to 15thDay
111%38%39%8%
315
16th to endDay
317%42%31%4
315
October1st to 15thDay
17%28%39%20%2
315
16th to endDay
17%21%36%29%3
336
November1st to 15thDay
5%6%17%31%31%7%
189
16th to endDay
5%10%22%34%23%2
135
December1st to 15thDay
7%9%26%46%9%
83
16th to endDay
15%12%23%37%10%
64
January1st to 15thNight
10%310%37%28%8%
720
16th to endNight
11%413%39%25%6%
768
February1st to 15thNight
9%6%10%37%28%7%
704
16th to endNight
9%10%10%39%23%5%
632
March1st to 15thNight
5%6%13%42%25%6%
720
16th to endNight
5%7%13%35%32%4
768
April1st to 15thNight
6%9%14%39%26%4
719
16th to endNight
46%15%32%34%7%
720
May1st to 15thNight
139%39%36%9%
707
16th to endNight
2412%33%40%6%
443
June1st to 15thNight
116%37%46%5%
360
16th to endNight
326%60%8%
360
July1st to 15thNight
13%70%14%
357
16th to endNight
18%60%27%
564
August1st to 15thNight
117%63%17%
681
16th to endNight
13%63%21%
764
September1st to 15thNight
1123%56%17%
720
16th to endNight
331%49%13%
716
October1st to 15thNight
427%35%39%10%
720
16th to endNight
317%36%39%11%
768
November1st to 15thNight
438%42%31%9%
760
16th to endNight
4310%39%32%9%
780
December1st to 15thNight
8%5%9%40%30%6%
736
16th to endNight
10%7%15%41%19%5%
768
Page generated at 2017-12-05 07:19:00. Version ac04

Copyright 2017 A. Danko


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