Montezuma Pass Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Montezuma Pass Overlook clear sky chart from 2005-11-05 to 2017-09-20.

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
73%
15528
35%
46921
30%
15490
79%
15490
52%
22609

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
73%
716
33%
2327
33%
716
79%
716
53%
1053
January16th to endNight
63%
768
35%
2496
30%
768
73%
768
43%
1240
February1st to 15thNight
70%
697
37%
2213
34%
696
80%
696
53%
1006
February16th to endNight
61%
632
41%
1795
32%
632
71%
632
54%
892
March1st to 15thNight
65%
720
41%
1980
31%
720
74%
720
59%
956
March16th to endNight
69%
768
39%
2112
27%
768
78%
768
61%
999
April1st to 15thNight
66%
665
37%
1924
25%
665
76%
665
59%
887
April16th to endNight
66%
540
43%
1800
35%
540
80%
540
67%
691
May1st to 15thNight
71%
539
38%
1673
31%
539
80%
539
69%
660
May16th to endNight
78%
562
43%
1684
36%
561
84%
561
75%
657
June1st to 15thNight
83%
540
35%
1620
30%
540
85%
540
67%
676
June16th to endNight
86%
540
29%
1620
27%
540
86%
540
53%
778
July1st to 15thNight
79%
510
14%
1530
13%
510
79%
510
32%
924
July16th to endNight
77%
564
11%
1593
10%
531
77%
531
23%
1072
August1st to 15thNight
79%
539
19%
1611
18%
536
80%
536
32%
977
August16th to endNight
81%
573
26%
1893
27%
573
81%
573
36%
1047
September1st to 15thNight
76%
708
24%
1968
21%
708
77%
708
37%
1195
September16th to endNight
86%
675
40%
1869
33%
675
87%
675
60%
914
October1st to 15thNight
81%
660
39%
1936
33%
660
84%
660
63%
869
October16th to endNight
85%
704
42%
2112
37%
704
87%
704
69%
891
November1st to 15thNight
79%
700
42%
2100
36%
700
85%
700
68%
883
November16th to endNight
67%
720
40%
2229
34%
720
74%
720
53%
1042
December1st to 15thNight
70%
720
37%
2340
37%
720
75%
720
51%
1078
December16th to endNight
63%
768
35%
2496
34%
768
69%
768
45%
1222

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
321342445%6%60%
47906
Night
2213323446%64%
47124
TransparencyDay
22%46%12%27%27%
47601
Night
18%37%15%28%25%
46930
SeeingDay
5%7%19%29%26%12%
5386
Night
3214%37%35%6%
15541

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
1323424437%63%
1611
16th to endDay
4424324445%58%
1728
February1st to 15thDay
3312312235%68%
1640
16th to endDay
2414423345%64%
1678
March1st to 15thDay
121332435%5%66%
1980
16th to endDay
2213212245%70%
2112
April1st to 15thDay
1112223346%70%
2021
16th to endDay
11112113380%
2160
May1st to 15thDay
12212135%77%
2274
16th to endDay
1111222479%
2429
June1st to 15thDay
1112212235%75%
2340
16th to endDay
22144345%5%6%60%
2340
July1st to 15thDay
6%326%7%5%8%8%9%10%31%
2340
16th to endDay
8%6%38%9%6%10%7%8%8%20%
2467
August1st to 15thDay
7%5%37%8%5%8%7%7%8%31%
2340
16th to endDay
4326%7%5%6%6%8%10%37%
2309
September1st to 15thDay
8%5%35%6%45%5%6%6%41%
1988
16th to endDay
422342335%5%62%
1860
October1st to 15thDay
1113323336%69%
1694
16th to endDay
111221223475%
1760
November1st to 15thDay
1112113336%74%
1759
16th to endDay
3213312335%68%
1728
December1st to 15thDay
3213423438%62%
1620
16th to endDay
242432335%7%61%
1728
January1st to 15thNight
2213323345%65%
2327
16th to endNight
4314433445%58%
2496
February1st to 15thNight
12232335%6%67%
2209
16th to endNight
1213424335%66%
1795
March1st to 15thNight
1212312346%69%
1980
16th to endNight
1112313225%72%
2112
April1st to 15thNight
122322334471%
1924
16th to endNight
11111222479%
1800
May1st to 15thNight
1112236%77%
1673
16th to endNight
11111122384%
1684
June1st to 15thNight
211111225%77%
1620
16th to endNight
12122245%5%7%65%
1620
July1st to 15thNight
2325%5%45%7%9%13%39%
1620
16th to endNight
5%415%5%5%8%8%11%14%28%
1701
August1st to 15thNight
23245%35%7%8%11%44%
1620
16th to endNight
5%323425%6%7%13%45%
1893
September1st to 15thNight
6%4245%25%5%6%9%46%
1968
16th to endNight
322212345%70%
1869
October1st to 15thNight
12312245%73%
1936
16th to endNight
12212235%77%
2112
November1st to 15thNight
11222235%76%
2100
16th to endNight
3413213235%67%
2229
December1st to 15thNight
3212223446%65%
2340
16th to endNight
22245%24345%61%
2496

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
20%3413%32%25%
1612
16th to endDay
24%1318%30%21%
1728
February1st to 15thDay
18%1213%32%32%
1640
16th to endDay
22%1213%32%27%
1678
March1st to 15thDay
16%239%36%32%
1980
16th to endDay
16%128%36%33%
2112
April1st to 15thDay
14%119%39%33%
2021
16th to endDay
9%116%30%49%
2160
May1st to 15thDay
10%127%28%49%
2274
16th to endDay
8%226%31%49%
2432
June1st to 15thDay
12%125%24%54%
2340
16th to endDay
22%348%23%37%
2340
July1st to 15thDay
39%11%16%13%11%8%
2201
16th to endDay
51%13%19%10%4
2312
August1st to 15thDay
42%10%14%16%13%2
2325
16th to endDay
35%9%15%17%12%8%
2309
September1st to 15thDay
37%6%9%18%19%7%
1988
16th to endDay
21%3416%34%20%
1860
October1st to 15thDay
15%36%15%28%30%
1694
16th to endDay
12%2313%30%38%
1760
November1st to 15thDay
10%1314%37%31%
1759
16th to endDay
17%2214%32%30%
1728
December1st to 15thDay
21%2418%34%18%
1620
16th to endDay
21%26%18%32%17%
1728
January1st to 15thNight
17%35%13%32%26%
2327
16th to endNight
24%3417%31%18%
2496
February1st to 15thNight
17%2415%29%30%
2220
16th to endNight
19%1315%33%25%
1795
March1st to 15thNight
15%2212%32%33%
1980
16th to endNight
15%1311%35%31%
2112
April1st to 15thNight
15%1312%39%28%
1924
16th to endNight
9%229%29%46%
1800
May1st to 15thNight
8%228%34%43%
1674
16th to endNight
6%2310%36%41%
1685
June1st to 15thNight
12%125%29%49%
1620
16th to endNight
17%4410%25%37%
1620
July1st to 15thNight
28%12%23%17%11%7%
1530
16th to endNight
36%14%29%13%31
1593
August1st to 15thNight
28%12%18%20%16%3
1611
16th to endNight
27%8%21%19%14%8%
1893
September1st to 15thNight
30%7%13%20%19%7%
1968
16th to endNight
15%3418%39%17%
1869
October1st to 15thNight
13%27%19%29%27%
1936
16th to endNight
11%1414%28%38%
2112
November1st to 15thNight
11%1419%34%29%
2100
16th to endNight
20%1314%29%31%
2229
December1st to 15thNight
19%25%18%33%20%
2340
16th to endNight
23%27%19%30%16%
2496

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
310%25%41%20%
90
16th to endDay
7%7%20%32%23%8%
96
February1st to 15thDay
7%9%15%32%29%5%
155
16th to endDay
7%20%31%23%15%2
238
March1st to 15thDay
317%30%22%18%7%
270
16th to endDay
417%28%24%15%9%
288
April1st to 15thDay
415%31%27%17%4
269
16th to endDay
218%34%27%12%5%
270
May1st to 15thDay
315%34%25%13%7%
288
16th to endDay
27%28%40%14%5%
330
June1st to 15thDay
5%221%41%18%10%
315
16th to endDay
411%38%30%14%
315
July1st to 15thDay
8%6%33%35%15%
305
16th to endDay
12%15%24%32%24%
327
August1st to 15thDay
8%1319%39%28%
315
16th to endDay
4320%44%25%
332
September1st to 15thDay
12%17%28%38%11%
315
16th to endDay
6%313%32%31%12%
272
October1st to 15thDay
220%29%31%15%
134
16th to endDay
15%8%27%30%28%
96
November1st to 15thDay
17%23%23%37%6%
90
16th to endDay
8%35%26%25%3
90
December1st to 15thDay
5%415%31%28%14%
90
16th to endDay
12%8%27%28%23%
96
January1st to 15thNight
3215%46%28%3
720
16th to endNight
4320%43%25%2
768
February1st to 15thNight
2416%43%28%4
704
16th to endNight
2427%44%19%1
632
March1st to 15thNight
25%22%42%23%3
720
16th to endNight
1320%43%26%3
768
April1st to 15thNight
2421%49%20%1
665
16th to endNight
1226%47%19%2
540
May1st to 15thNight
320%44%27%2
540
16th to endNight
1114%47%32%1
563
June1st to 15thNight
38%47%37%2
540
16th to endNight
11437%52%2
540
July1st to 15thNight
4321%60%10%
510
16th to endNight
7%114%60%16%
564
August1st to 15thNight
4112%62%18%
539
16th to endNight
6%215%58%16%
573
September1st to 15thNight
8%418%55%12%
708
16th to endNight
4433%49%7%
675
October1st to 15thNight
111%43%35%7%
660
16th to endNight
18%37%43%8%
704
November1st to 15thNight
1114%39%37%6%
700
16th to endNight
6%218%35%30%7%
720
December1st to 15thNight
4415%40%28%6%
720
16th to endNight
3422%43%20%5%
768
Page generated at 2017-09-21 04:18:20. Version ac04

Copyright 2017 A. Danko


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