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 2018-02-14.

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
41%
16273
14%
48706
11%
16233
44%
16233
21%
33478

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
29%
916
7%
2846
6%
914
30%
914
11%
2300
January16th to endNight
33%
832
10%
2704
8%
832
36%
832
13%
2055
February1st to 15thNight
24%
755
8%
2470
7%
754
27%
754
9%
1989
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%
539
26%
1611
21%
536
75%
536
48%
801
August16th to endNight
68%
573
33%
1728
26%
573
72%
573
50%
842
September1st to 15thNight
60%
603
26%
1863
20%
603
67%
603
39%
1006
September16th to endNight
60%
716
26%
1980
19%
716
64%
716
41%
1127
October1st to 15thNight
48%
720
20%
2139
15%
720
53%
720
30%
1326
October16th to endNight
45%
768
21%
2336
15%
768
51%
768
29%
1464
November1st to 15thNight
30%
848
13%
2558
9%
848
35%
848
17%
1862
November16th to endNight
29%
975
10%
2730
7%
975
33%
975
18%
2000
December1st to 15thNight
27%
975
6%
2730
4%
975
29%
975
11%
2239
December16th to endNight
20%
1040
8%
3058
4%
1040
24%
1040
10%
2524

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%10%5%8%6%34446%37%
49379
Night
5%10%5%8%6%35%45%6%37%
48877
Cloud CoverDay
6%10%48%6%3445%6%38%
49380
Night
5%9%5%8%6%35%45%7%38%
48879
TransparencyDay
46%6%12%18%12%3
49053
Night
45%7%14%18%10%3
48707
SeeingDay
14%20%31%20%11%2
6332
Night
11%14%26%29%15%2
16283

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
315%9%12%9%35%445%23%
1431
16th to endDay
217%8%15%8%3443427%
1872
February1st to 15thDay
417%8%15%9%35%5%35%21%
1693
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%55%
2340
16th to endDay
331243346%6%59%
2474
September1st to 15thDay
7%5%24323235%58%
2094
16th to endDay
8%7%23433448%50%
1980
October1st to 15thDay
11%10%35%43445%6%38%
1820
16th to endDay
7%10%48%5%245%46%40%
1887
November1st to 15thDay
9%12%6%9%6%34446%30%
1618
16th to endDay
413%7%12%7%45%44430%
1560
December1st to 15thDay
413%9%13%11%5%6%5%5%419%
1560
16th to endDay
6%17%7%17%9%35%335%20%
1514
January1st to 15thNight
414%7%12%11%5%6%44423%
2846
16th to endNight
314%8%12%8%45%5%45%26%
2704
February1st to 15thNight
416%9%15%9%45%44422%
2459
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
32134346%7%9%55%
1620
16th to endNight
2313323447%64%
1728
September1st to 15thNight
7%313424445%58%
1863
16th to endNight
6%5%2342335%6%55%
1980
October1st to 15thNight
9%9%24423437%47%
2139
16th to endNight
7%8%36%5%24446%46%
2336
November1st to 15thNight
8%12%5%10%6%35%445%32%
2558
16th to endNight
411%6%9%8%45%447%32%
2730
December1st to 15thNight
414%7%14%10%5%7%43422%
2730
16th to endNight
414%10%15%10%45%44419%
3058

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%8%45%45%6%24%
1431
16th to endDay
216%8%14%9%3434428%
1872
February1st to 15thDay
316%8%13%9%4445%6%22%
1693
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%2243345%5%7%55%
2340
16th to endDay
321333345%7%60%
2474
September1st to 15thDay
7%5%23423245%58%
2094
16th to endDay
8%6%1333345%7%51%
1980
October1st to 15thDay
11%10%35%5%25%45%6%39%
1820
16th to endDay
7%9%37%5%2445%6%41%
1887
November1st to 15thDay
8%11%6%9%6%445%5%5%32%
1618
16th to endDay
412%7%11%7%4445%5%32%
1560
December1st to 15thDay
412%9%11%11%5%6%5%5%5%21%
1560
16th to endDay
5%17%7%16%9%44445%21%
1514
January1st to 15thNight
313%7%12%9%5%6%45%6%24%
2846
16th to endNight
214%7%12%8%35%5%5%6%27%
2704
February1st to 15thNight
315%8%15%8%45%445%23%
2459
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
3233346%7%9%56%
1620
16th to endNight
321232335%6%65%
1728
September1st to 15thNight
6%313324445%58%
1863
16th to endNight
6%5%1332335%6%56%
1980
October1st to 15thNight
9%8%23423446%49%
2139
16th to endNight
7%8%25%5%23446%48%
2336
November1st to 15thNight
7%12%5%10%5%3445%6%33%
2558
16th to endNight
410%6%9%7%45%5%5%7%34%
2730
December1st to 15thNight
412%7%12%10%5%7%346%23%
2730
16th to endNight
312%9%16%10%45%45%5%21%
3058

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%5%1
1431
16th to endDay
61%6%12%10%6%1
1872
February1st to 15thDay
64%6%12%11%3
1693
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
25%6%9%20%27%11%
2325
16th to endDay
22%410%26%27%9%
2474
September1st to 15thDay
28%48%22%29%5%
2094
16th to endDay
31%5%14%26%17%3
1980
October1st to 15thDay
44%7%17%22%7%
1820
16th to endDay
42%9%17%22%7%1
1887
November1st to 15thDay
53%7%14%17%42
1618
16th to endDay
55%8%14%16%5%
1560
December1st to 15thDay
65%8%10%10%5%
1560
16th to endDay
68%412%9%31
1514
January1st to 15thNight
62%9%11%9%5%2
2846
16th to endNight
57%7%14%13%5%1
2704
February1st to 15thNight
64%7%8%13%5%
2470
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%13%24%24%13%
1611
16th to endNight
18%410%24%30%12%
1728
September1st to 15thNight
26%5%9%22%28%7%
1863
16th to endNight
27%5%15%30%18%3
1980
October1st to 15thNight
35%6%19%26%11%1
2139
16th to endNight
36%7%18%26%11%
2336
November1st to 15thNight
51%7%14%18%5%2
2558
16th to endNight
49%9%18%14%8%
2730
December1st to 15thNight
63%7%13%9%4
2730
16th to endNight
66%6%9%10%41
3058

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
7%32%25%17%10%6%
92
16th to endDay
15%21%33%16%9%2
144
February1st to 15thDay
28%30%16%17%6%
130
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%12%36%31%10%1
315
16th to endDay
5%14%34%28%13%3
332
September1st to 15thDay
13%15%35%22%10%3
315
16th to endDay
17%13%35%18%13%2
315
October1st to 15thDay
20%21%27%21%7%
155
16th to endDay
21%19%29%20%5%3
144
November1st to 15thDay
8%27%29%14%11%8%
135
16th to endDay
15%28%36%15%3
135
December1st to 15thDay
14%25%23%22%13%
135
16th to endDay
20%35%22%12%43
109
January1st to 15thNight
11%21%30%25%9%1
919
16th to endNight
10%17%32%27%10%1
832
February1st to 15thNight
13%21%31%25%7%1
760
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
539
16th to endNight
45%16%38%31%3
573
September1st to 15thNight
7%322%36%24%4
603
16th to endNight
10%6%18%31%26%6%
716
October1st to 15thNight
13%8%25%32%16%2
720
16th to endNight
13%10%26%32%11%4
768
November1st to 15thNight
14%20%28%26%8%1
848
16th to endNight
11%24%30%24%7%1
975
December1st to 15thNight
14%21%28%27%6%1
975
16th to endNight
13%23%32%20%9%1
1040
Page generated at 2018-02-15 08:58:50. Version ac04

Copyright 2018 A. Danko


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