Upper Geyser Basin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Upper Geyser Basin 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
40%
15492
14%
46366
11%
15452
44%
15452
21%
31856

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
28%
846
7%
2627
6%
844
29%
844
10%
2135
January16th to endNight
34%
768
10%
2496
8%
768
38%
768
14%
1884
February1st to 15thNight
25%
699
8%
2288
7%
698
27%
698
9%
1833
February16th to endNight
25%
632
6%
1997
5%
632
27%
632
9%
1605
March1st to 15thNight
32%
720
8%
2010
6%
720
34%
720
16%
1534
March16th to endNight
34%
768
8%
2112
5%
768
36%
768
17%
1592
April1st to 15thNight
32%
593
9%
1811
5%
593
36%
593
18%
1314
April16th to endNight
37%
540
15%
1620
11%
540
41%
540
22%
1104
May1st to 15thNight
46%
539
13%
1604
10%
539
48%
539
26%
1024
May16th to endNight
45%
562
8%
1498
6%
561
47%
561
21%
1088
June1st to 15thNight
44%
421
11%
1321
8%
421
48%
421
23%
858
June16th to endNight
65%
360
23%
1260
24%
360
71%
360
46%
582
July1st to 15thNight
80%
340
21%
1190
24%
340
84%
340
48%
529
July16th to endNight
70%
538
25%
1530
24%
505
75%
505
55%
713
August1st to 15thNight
71%
527
26%
1575
22%
524
74%
524
49%
781
August16th to endNight
65%
525
32%
1583
25%
525
70%
525
49%
775
September1st to 15thNight
58%
553
27%
1708
21%
553
66%
553
39%
930
September16th to endNight
61%
656
26%
1815
19%
656
65%
656
43%
1011
October1st to 15thNight
49%
660
21%
1961
16%
660
53%
660
29%
1226
October16th to endNight
44%
704
18%
2141
13%
704
49%
704
27%
1368
November1st to 15thNight
30%
781
14%
2356
9%
781
35%
781
18%
1692
November16th to endNight
30%
900
10%
2520
7%
900
33%
900
18%
1852
December1st to 15thNight
25%
900
5%
2520
3%
900
26%
900
9%
2104
December16th to endNight
22%
960
8%
2823
4%
960
25%
960
10%
2322

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%11%5%8%6%34446%37%
47619
Night
5%10%5%8%6%3445%6%37%
46537
Cloud CoverDay
6%10%5%8%6%3445%6%38%
47620
Night
5%9%5%8%6%3445%7%38%
46539
TransparencyDay
46%6%12%18%11%3
47293
Night
45%7%14%18%10%3
46367
SeeingDay
14%19%31%20%11%2
5749
Night
11%14%27%29%15%2
15502

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
316%10%12%9%35%446%23%
1320
16th to endDay
217%8%14%8%3433427%
1728
February1st to 15thDay
317%9%14%9%35%445%22%
1575
16th to endDay
216%12%19%9%35%33419%
1476
March1st to 15thDay
317%8%12%8%35%45%7%22%
1949
16th to endDay
6%20%8%10%6%45%45%6%21%
2111
April1st to 15thDay
7%17%8%10%8%45%445%23%
2135
16th to endDay
8%16%6%9%7%34447%26%
2340
May1st to 15thDay
8%11%38%7%35%5%46%34%
2343
16th to endDay
14%12%48%6%46%5%5%7%24%
2616
June1st to 15thDay
14%8%45%6%35%5%5%7%32%
2636
16th to endDay
34134235%5%8%57%
2700
July1st to 15thDay
331343446%9%56%
2700
16th to endDay
331342435%5%62%
2530
August1st to 15thDay
5%3134245%5%7%56%
2290
16th to endDay
431343345%6%58%
2267
September1st to 15thDay
7%5%24323235%57%
1920
16th to endDay
7%6%23432448%52%
1815
October1st to 15thDay
12%11%36%434446%37%
1669
16th to endDay
8%11%48%5%245%46%38%
1730
November1st to 15thDay
10%12%6%9%6%34446%32%
1491
16th to endDay
413%7%12%7%45%43430%
1440
December1st to 15thDay
5%14%9%13%11%5%6%5%5%417%
1440
16th to endDay
6%17%7%16%10%34335%21%
1398
January1st to 15thNight
415%7%12%10%5%6%44423%
2627
16th to endNight
315%9%12%7%35%5%45%27%
2496
February1st to 15thNight
416%9%15%8%4444423%
2277
16th to endNight
313%8%17%9%5%5%5%46%19%
1997
March1st to 15thNight
214%7%11%8%3445%7%29%
2010
16th to endNight
414%6%8%7%45%5%5%8%27%
2109
April1st to 15thNight
7%14%7%7%6%3445%8%30%
1811
16th to endNight
8%11%45%435%6%5%7%37%
1620
May1st to 15thNight
6%7%36%6%45%5%5%7%41%
1604
16th to endNight
14%8%35%5%35%6%7%8%31%
1498
June1st to 15thNight
13%6%25%435%5%6%8%37%
1321
16th to endNight
4213313448%62%
1260
July1st to 15thNight
213235%5%6%10%58%
1260
16th to endNight
21232346%7%64%
1636
August1st to 15thNight
32124346%7%9%55%
1584
16th to endNight
3313323346%64%
1583
September1st to 15thNight
7%314424445%57%
1708
16th to endNight
5%5%2332335%6%58%
1815
October1st to 15thNight
9%9%24423437%47%
1961
16th to endNight
7%9%36%5%24446%45%
2141
November1st to 15thNight
8%12%5%10%6%34345%33%
2356
16th to endNight
411%6%9%7%45%447%32%
2520
December1st to 15thNight
415%8%14%10%6%7%43420%
2520
16th to endNight
414%10%16%10%4444420%
2823

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
314%10%12%7%45%45%6%24%
1320
16th to endDay
216%8%14%8%3334429%
1728
February1st to 15thDay
316%9%13%9%3445%6%23%
1575
16th to endDay
315%12%18%9%34445%19%
1476
March1st to 15thDay
316%7%12%8%36%5%47%24%
1949
16th to endDay
5%19%8%10%6%35%5%5%6%22%
2112
April1st to 15thDay
7%17%8%10%7%5%5%445%24%
2135
16th to endDay
8%16%5%9%7%45%5%46%26%
2340
May1st to 15thDay
8%11%38%7%35%45%6%34%
2343
16th to endDay
15%11%48%7%46%5%5%7%24%
2616
June1st to 15thDay
15%8%25%6%35%5%5%7%33%
2636
16th to endDay
431342445%8%57%
2700
July1st to 15thDay
331343446%9%56%
2700
16th to endDay
331342435%6%62%
2530
August1st to 15thDay
5%2144345%5%7%56%
2290
16th to endDay
421333345%6%59%
2267
September1st to 15thDay
7%5%24424245%57%
1920
16th to endDay
7%5%23332448%53%
1815
October1st to 15thDay
11%11%36%5%2435%7%38%
1669
16th to endDay
8%10%37%6%2445%6%38%
1730
November1st to 15thDay
9%11%6%9%5%335%45%33%
1491
16th to endDay
413%7%11%7%445%5%5%31%
1440
December1st to 15thDay
413%10%11%12%5%7%5%5%5%18%
1440
16th to endDay
5%17%7%16%9%44345%22%
1398
January1st to 15thNight
314%7%12%9%5%6%446%24%
2627
16th to endNight
215%7%12%8%345%5%6%28%
2496
February1st to 15thNight
315%8%15%8%35%445%24%
2277
16th to endNight
312%8%16%10%5%445%7%21%
1997
March1st to 15thNight
212%6%11%7%45%5%6%7%31%
2010
16th to endNight
413%6%8%6%45%6%6%8%29%
2112
April1st to 15thNight
7%13%6%7%5%3446%7%32%
1811
16th to endNight
7%11%35%435%6%7%7%37%
1620
May1st to 15thNight
6%8%35%5%35%5%6%7%42%
1604
16th to endNight
13%8%346%36%6%6%9%32%
1497
June1st to 15thNight
13%6%25%5%2447%8%39%
1321
16th to endNight
4113214448%63%
1260
July1st to 15thNight
2123345%7%10%58%
1260
16th to endNight
211222345%7%65%
1636
August1st to 15thNight
3133346%7%8%57%
1584
16th to endNight
3212323346%65%
1583
September1st to 15thNight
6%314424445%58%
1708
16th to endNight
6%5%1322335%6%58%
1815
October1st to 15thNight
9%9%24423446%49%
1961
16th to endNight
7%8%26%5%23445%47%
2141
November1st to 15thNight
7%12%5%10%42445%6%35%
2356
16th to endNight
411%6%9%7%35%5%5%7%34%
2520
December1st to 15thNight
413%8%13%10%5%7%445%21%
2520
16th to endNight
313%9%17%10%45%445%21%
2823

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
60%8%12%11%41
1320
16th to endDay
61%6%12%11%6%1
1728
February1st to 15thDay
63%7%13%12%3
1575
16th to endDay
69%6%9%10%31
1476
March1st to 15thDay
59%9%13%13%3
1949
16th to endDay
63%8%13%12%2
2112
April1st to 15thDay
63%6%11%13%4
2135
16th to endDay
57%8%13%16%2
2340
May1st to 15thDay
48%7%13%24%5%
2343
16th to endDay
57%9%13%14%4
2620
June1st to 15thDay
48%7%15%19%7%1
2636
16th to endDay
23%5%10%27%26%6%
2700
July1st to 15thDay
22%5%11%24%24%11%
2541
16th to endDay
21%47%17%29%19%
2373
August1st to 15thDay
24%6%9%20%27%11%
2275
16th to endDay
23%410%25%26%10%
2267
September1st to 15thDay
29%48%22%28%6%
1920
16th to endDay
29%6%15%27%17%4
1815
October1st to 15thDay
46%7%17%21%7%
1669
16th to endDay
44%9%17%22%5%1
1730
November1st to 15thDay
51%8%14%17%42
1491
16th to endDay
55%7%14%15%5%
1440
December1st to 15thDay
67%8%10%9%3
1440
16th to endDay
67%5%12%9%31
1398
January1st to 15thNight
62%9%11%9%5%1
2627
16th to endNight
57%7%14%13%5%2
2496
February1st to 15thNight
64%7%8%13%5%
2288
16th to endNight
64%7%12%9%41
1997
March1st to 15thNight
52%10%15%15%5%
2010
16th to endNight
51%8%18%16%3
2112
April1st to 15thNight
51%7%19%16%6%
1811
16th to endNight
43%8%18%24%4
1620
May1st to 15thNight
38%7%18%27%7%
1605
16th to endNight
45%11%19%17%6%
1498
June1st to 15thNight
39%9%16%24%8%1
1321
16th to endNight
17%6%11%31%25%7%
1260
July1st to 15thNight
16%6%13%28%22%11%
1190
16th to endNight
16%310%19%30%19%
1530
August1st to 15thNight
18%6%12%23%25%13%
1575
16th to endNight
19%49%23%30%12%
1583
September1st to 15thNight
27%5%9%23%27%7%
1708
16th to endNight
25%5%14%31%19%3
1815
October1st to 15thNight
36%6%19%26%10%
1961
16th to endNight
37%7%18%25%9%
2141
November1st to 15thNight
50%7%14%19%6%2
2356
16th to endNight
49%8%18%13%8%
2520
December1st to 15thNight
66%7%12%9%3
2520
16th to endNight
66%6%10%10%41
2823

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
8%29%21%19%11%9%
61
16th to endDay
12%17%35%19%11%3
96
February1st to 15thDay
27%26%16%21%6%1
90
16th to endDay
17%36%28%14%2
135
March1st to 15thDay
20%39%31%6%1
270
16th to endDay
20%32%35%9%2
288
April1st to 15thDay
16%31%34%11%5%
269
16th to endDay
27%23%30%12%5%
270
May1st to 15thDay
18%18%31%21%7%3
300
16th to endDay
20%13%23%21%16%3
517
June1st to 15thDay
17%16%25%24%14%2
495
16th to endDay
7%15%31%26%16%3
495
July1st to 15thDay
5%10%27%29%23%4
475
16th to endDay
314%42%25%12%2
362
August1st to 15thDay
6%13%37%32%10%1
300
16th to endDay
5%17%35%26%11%3
268
September1st to 15thDay
13%18%40%18%7%1
255
16th to endDay
12%13%38%19%13%1
255
October1st to 15thDay
22%17%31%18%10%
109
16th to endDay
26%19%20%20%7%5%
96
November1st to 15thDay
8%15%33%15%15%11%
90
16th to endDay
13%24%41%17%3
90
December1st to 15thDay
17%31%23%21%6%
90
16th to endDay
15%28%24%19%6%5%
73
January1st to 15thNight
11%22%30%23%10%1
849
16th to endNight
10%16%31%28%10%1
768
February1st to 15thNight
12%20%31%25%7%1
704
16th to endNight
11%22%30%25%9%
632
March1st to 15thNight
10%21%29%27%9%1
720
16th to endNight
13%16%29%28%10%
768
April1st to 15thNight
15%14%33%25%9%1
593
16th to endNight
13%11%31%29%12%1
540
May1st to 15thNight
10%11%27%31%17%1
540
16th to endNight
18%8%22%32%17%
563
June1st to 15thNight
15%6%27%31%18%
421
16th to endNight
4421%41%24%2
360
July1st to 15thNight
3110%42%39%2
340
16th to endNight
3219%44%27%2
538
August1st to 15thNight
4215%41%33%2
527
16th to endNight
45%18%39%29%2
525
September1st to 15thNight
7%423%38%22%3
553
16th to endNight
9%6%19%31%26%6%
656
October1st to 15thNight
14%8%24%32%16%2
660
16th to endNight
13%10%27%30%12%4
704
November1st to 15thNight
14%19%29%25%9%1
781
16th to endNight
10%24%30%25%8%1
900
December1st to 15thNight
15%22%28%24%7%1
900
16th to endNight
12%22%31%21%10%1
960
Page generated at 2017-08-13 12:16:26. Version ac04

Copyright 2017 A. Danko


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