Mammoth Hot Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mammoth Hot Springs clear sky chart from 2005-11-05 to 2017-03-24.

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
37%
15099
13%
45216
10%
15057
40%
15057
20%
31383

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
23%
868
8%
2655
6%
865
25%
865
11%
2132
January16th to endNight
28%
768
11%
2511
9%
768
31%
768
14%
1874
February1st to 15thNight
22%
698
7%
2288
5%
696
25%
696
10%
1794
February16th to endNight
23%
632
6%
2007
5%
632
25%
632
10%
1605
March1st to 15thNight
29%
720
8%
2010
4%
720
32%
720
16%
1517
March16th to endNight
31%
740
8%
2035
4%
740
34%
740
17%
1520
April1st to 15thNight
32%
538
9%
1655
5%
538
35%
538
17%
1211
April16th to endNight
35%
495
13%
1485
10%
495
38%
495
19%
1024
May1st to 15thNight
42%
494
14%
1451
11%
494
45%
494
23%
968
May16th to endNight
39%
514
8%
1370
5%
513
41%
513
19%
1006
June1st to 15thNight
42%
368
10%
1193
7%
368
47%
368
21%
782
June16th to endNight
58%
330
18%
1155
15%
330
66%
330
39%
564
July1st to 15thNight
74%
310
19%
1085
20%
310
79%
310
42%
528
July16th to endNight
63%
482
23%
1369
21%
449
68%
449
48%
661
August1st to 15thNight
68%
494
25%
1476
21%
491
71%
491
44%
759
August16th to endNight
61%
525
30%
1582
23%
525
66%
525
45%
803
September1st to 15thNight
59%
544
26%
1699
20%
544
66%
544
37%
940
September16th to endNight
59%
656
25%
1815
18%
656
64%
656
41%
1039
October1st to 15thNight
47%
660
20%
1966
14%
660
52%
660
28%
1242
October16th to endNight
38%
704
17%
2145
11%
704
44%
704
26%
1392
November1st to 15thNight
27%
799
13%
2374
9%
799
31%
799
18%
1700
November16th to endNight
28%
900
9%
2520
5%
900
31%
900
17%
1873
December1st to 15thNight
20%
900
4%
2520
2%
900
21%
900
10%
2109
December16th to endNight
20%
960
8%
2850
5%
960
23%
960
10%
2340

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
6%9%5%8%7%35%5%5%6%35%
45725
Night
49%48%7%35%5%6%7%36%
45386
Cloud CoverDay
6%10%5%8%7%35%5%5%6%35%
45726
Night
5%9%49%7%35%5%5%7%36%
45388
TransparencyDay
48%6%12%17%10%3
45398
Night
47%6%15%18%9%2
45217
SeeingDay
15%22%31%19%9%1
5150
Night
12%14%29%29%12%1
15109

By Month

Percentage Cloud Cover NW (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
213%8%13%10%45%6%5%6%22%
1292
16th to endDay
113%9%13%8%45%5%46%27%
1710
February1st to 15thDay
213%9%13%8%36%45%7%24%
1575
16th to endDay
214%9%15%10%46%445%21%
1464
March1st to 15thDay
211%6%13%10%46%6%5%6%25%
1950
16th to endDay
417%6%11%8%45%5%47%23%
2032
April1st to 15thDay
7%17%7%11%7%35%5%5%7%21%
1963
16th to endDay
7%16%6%9%8%345%5%6%24%
2145
May1st to 15thDay
10%11%5%9%7%45%445%30%
2166
16th to endDay
15%13%6%8%7%46%5%45%20%
2392
June1st to 15thDay
13%9%46%7%36%5%6%6%30%
2435
16th to endDay
44245%35%5%6%8%50%
2475
July1st to 15thDay
4325%5%25%5%6%8%49%
2475
16th to endDay
3323435%45%7%57%
2382
August1st to 15thDay
5%3246%45%46%8%48%
2145
16th to endDay
43145%345%5%6%55%
2267
September1st to 15thDay
7%5%25%42345%5%52%
1928
16th to endDay
6%5%145%335%5%7%49%
1815
October1st to 15thDay
11%11%37%6%2445%7%34%
1664
16th to endDay
8%9%39%6%3445%8%35%
1726
November1st to 15thDay
6%10%7%8%7%45%446%35%
1473
16th to endDay
210%6%11%8%46%5%5%5%33%
1440
December1st to 15thDay
311%6%13%9%5%7%7%6%8%20%
1440
16th to endDay
5%12%7%15%11%37%45%6%20%
1371
January1st to 15thNight
314%5%12%10%5%7%5%6%5%24%
2655
16th to endNight
212%6%12%8%45%5%5%8%28%
2511
February1st to 15thNight
312%7%12%9%46%5%6%7%24%
2277
16th to endNight
110%7%13%11%5%7%6%6%7%22%
2007
March1st to 15thNight
110%6%11%9%45%5%7%7%30%
2010
16th to endNight
412%49%6%45%6%6%8%30%
2032
April1st to 15thNight
6%11%6%8%6%35%5%5%8%31%
1655
16th to endNight
6%11%48%6%345%5%7%37%
1485
May1st to 15thNight
5%9%37%5%36%5%6%6%40%
1451
16th to endNight
12%9%27%6%36%5%7%9%29%
1370
June1st to 15thNight
11%7%25%5%25%5%7%8%39%
1193
16th to endNight
32133245%6%9%56%
1155
July1st to 15thNight
321342447%10%56%
1155
16th to endNight
121342336%7%63%
1474
August1st to 15thNight
22143346%7%9%52%
1485
16th to endNight
331332335%8%61%
1582
September1st to 15thNight
6%5%1443445%5%55%
1699
16th to endNight
5%5%1342345%7%57%
1815
October1st to 15thNight
9%8%36%5%2335%6%45%
1966
16th to endNight
6%7%26%6%3445%7%43%
2145
November1st to 15thNight
6%8%5%9%6%45%6%47%35%
2374
16th to endNight
311%6%8%7%46%5%6%7%34%
2520
December1st to 15thNight
311%6%12%8%5%9%7%6%6%20%
2520
16th to endNight
6%12%7%14%10%5%5%5%6%5%20%
2850

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
315%9%13%9%45%5%6%7%21%
1292
16th to endDay
115%9%12%8%35%446%27%
1710
February1st to 15thDay
313%10%15%8%45%45%5%24%
1575
16th to endDay
314%9%15%9%35%6%36%20%
1464
March1st to 15thDay
212%6%13%11%47%45%6%25%
1950
16th to endDay
5%17%6%11%8%45%446%24%
2033
April1st to 15thDay
7%16%8%11%7%36%45%6%21%
1963
16th to endDay
7%15%6%10%7%45%446%25%
2145
May1st to 15thDay
9%12%5%8%8%45%5%46%30%
2166
16th to endDay
15%14%5%7%7%46%6%5%6%20%
2392
June1st to 15thDay
14%9%37%6%46%6%5%7%29%
2435
16th to endDay
44245%445%6%7%50%
2475
July1st to 15thDay
4325%5%35%5%6%8%50%
2475
16th to endDay
22235%345%5%6%57%
2382
August1st to 15thDay
4415%6%35%5%6%9%48%
2145
16th to endDay
43145%3445%7%54%
2267
September1st to 15thDay
7%5%25%42335%6%52%
1928
16th to endDay
6%5%245%25%45%6%50%
1815
October1st to 15thDay
11%10%38%7%345%5%6%34%
1664
16th to endDay
8%10%5%8%6%34448%35%
1726
November1st to 15thDay
7%11%8%8%6%24446%34%
1473
16th to endDay
211%6%11%9%46%45%433%
1440
December1st to 15thDay
312%7%14%10%47%6%6%6%19%
1440
16th to endDay
6%14%7%14%10%36%5%5%6%19%
1371
January1st to 15thNight
415%7%12%10%5%4446%23%
2655
16th to endNight
313%7%13%8%45%45%6%28%
2511
February1st to 15thNight
314%8%13%10%45%45%6%23%
2277
16th to endNight
111%8%14%11%47%6%6%6%22%
2007
March1st to 15thNight
111%6%11%9%45%5%6%7%29%
2010
16th to endNight
412%48%6%36%6%6%8%30%
2035
April1st to 15thNight
6%12%5%7%6%35%5%6%6%32%
1655
16th to endNight
5%11%5%7%5%45%45%8%36%
1485
May1st to 15thNight
5%8%36%7%25%6%5%6%41%
1451
16th to endNight
11%8%37%6%45%7%7%8%30%
1369
June1st to 15thNight
11%7%15%5%245%6%9%39%
1193
16th to endNight
32133245%5%10%55%
1155
July1st to 15thNight
231242446%10%56%
1155
16th to endNight
121242345%7%63%
1474
August1st to 15thNight
2214325%5%8%9%53%
1485
16th to endNight
321332235%8%61%
1582
September1st to 15thNight
6%4234245%45%56%
1699
16th to endNight
5%3235%23347%56%
1815
October1st to 15thNight
9%8%26%42435%7%45%
1966
16th to endNight
6%8%37%5%3445%6%44%
2145
November1st to 15thNight
7%9%5%9%7%445%47%35%
2374
16th to endNight
412%6%8%7%45%45%6%33%
2520
December1st to 15thNight
412%7%14%9%6%8%6%6%5%20%
2520
16th to endNight
6%14%7%16%9%45%446%20%
2850

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
63%7%11%12%41
1292
16th to endDay
58%6%14%12%5%1
1710
February1st to 15thDay
62%7%14%12%2
1575
16th to endDay
67%5%11%10%31
1464
March1st to 15thDay
60%7%15%12%3
1950
16th to endDay
61%7%16%12%1
2033
April1st to 15thDay
64%6%12%13%2
1963
16th to endDay
58%5%16%15%3
2145
May1st to 15thDay
54%5%15%18%6%
2166
16th to endDay
63%7%14%12%2
2396
June1st to 15thDay
51%7%14%18%6%
2435
16th to endDay
29%5%10%27%20%6%
2475
July1st to 15thDay
29%5%10%22%22%9%
2316
16th to endDay
23%47%17%28%18%
2224
August1st to 15thDay
29%5%7%22%24%9%
2130
16th to endDay
27%47%24%23%11%
2267
September1st to 15thDay
33%38%21%26%6%
1928
16th to endDay
33%5%13%27%16%3
1815
October1st to 15thDay
49%5%15%21%7%
1664
16th to endDay
48%7%16%21%5%
1726
November1st to 15thDay
50%8%14%17%6%1
1473
16th to endDay
55%6%16%15%5%
1440
December1st to 15thDay
64%8%12%11%2
1440
16th to endDay
67%5%13%9%3
1371
January1st to 15thNight
64%6%12%11%41
2655
16th to endNight
56%6%15%14%5%2
2511
February1st to 15thNight
62%6%13%12%4
2288
16th to endNight
63%7%13%11%31
2007
March1st to 15thNight
54%7%17%15%4
2010
16th to endNight
51%8%20%15%3
2035
April1st to 15thNight
51%7%18%16%5%
1655
16th to endNight
46%8%20%20%3
1485
May1st to 15thNight
41%7%16%28%5%
1452
16th to endNight
49%9%19%16%5%
1370
June1st to 15thNight
40%9%20%20%8%
1193
16th to endNight
22%5%17%26%20%6%
1155
July1st to 15thNight
20%6%17%25%19%9%
1085
16th to endNight
18%5%8%19%30%16%
1369
August1st to 15thNight
21%6%13%23%24%10%
1476
16th to endNight
20%5%10%25%26%10%
1582
September1st to 15thNight
29%5%9%25%24%6%
1699
16th to endNight
27%5%16%31%17%2
1815
October1st to 15thNight
39%419%25%9%
1966
16th to endNight
40%6%18%24%9%
2145
November1st to 15thNight
50%6%16%18%5%1
2374
16th to endNight
52%7%19%12%6%1
2520
December1st to 15thNight
65%8%12%10%2
2520
16th to endNight
67%5%11%10%31
2850

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
6%18%33%23%13%5%
60
16th to endDay
9%21%39%18%9%1
93
February1st to 15thDay
23%24%28%18%31
90
16th to endDay
26%26%33%11%3
123
March1st to 15thDay
24%41%25%6%1
270
16th to endDay
29%28%29%11%1
260
April1st to 15thDay
25%23%33%14%2
209
16th to endDay
21%30%31%11%5%
210
May1st to 15thDay
17%24%31%18%6%1
258
16th to endDay
23%15%22%20%15%1
437
June1st to 15thDay
19%15%26%25%12%1
420
16th to endDay
8%19%29%25%16%1
420
July1st to 15thDay
8%12%29%28%18%2
400
16th to endDay
5%18%40%24%9%1
328
August1st to 15thDay
9%20%40%21%7%
255
16th to endDay
8%23%34%23%7%2
268
September1st to 15thDay
13%27%35%18%5%
255
16th to endDay
12%25%33%17%10%
255
October1st to 15thDay
19%21%31%20%6%
104
16th to endDay
25%15%32%18%6%2
96
November1st to 15thDay
8%16%33%21%16%3
90
16th to endDay
6%30%46%14%2
90
December1st to 15thDay
12%40%26%16%4
90
16th to endDay
23%18%28%17%7%4
69
January1st to 15thNight
16%18%34%21%7%
870
16th to endNight
11%16%38%24%7%
768
February1st to 15thNight
13%21%32%25%5%
704
16th to endNight
13%21%34%22%7%
632
March1st to 15thNight
11%24%28%27%7%1
720
16th to endNight
13%16%32%28%7%
740
April1st to 15thNight
15%16%29%27%10%
538
16th to endNight
13%12%31%26%15%
495
May1st to 15thNight
10%12%30%27%17%1
495
16th to endNight
16%10%26%31%15%
515
June1st to 15thNight
16%8%27%30%17%
368
16th to endNight
6%6%25%39%22%
330
July1st to 15thNight
4116%43%32%
310
16th to endNight
2422%47%21%
482
August1st to 15thNight
3318%46%25%1
494
16th to endNight
6%423%39%25%
525
September1st to 15thNight
9%423%40%19%2
544
16th to endNight
8%7%21%35%24%2
656
October1st to 15thNight
15%9%22%36%14%1
660
16th to endNight
13%13%30%27%11%3
704
November1st to 15thNight
16%18%32%24%7%
799
16th to endNight
15%21%31%24%6%
900
December1st to 15thNight
16%21%33%21%5%1
900
16th to endNight
16%22%31%21%7%
960
Page generated at 2017-03-25 10:39:47. Version ac04

Copyright 2017 A. Danko


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